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<document id="06F41B470A87CEBC704F5829FA3F1771" ID-DOI="10.11646/phytotaxa.438.2.2" ID-ISSN="1179-3163" ID-Zenodo-Dep="13872382" IM.bibliography_approvedBy="felipe" IM.illustrations_approvedBy="felipe" IM.materialsCitations_approvedBy="felipe" IM.metadata_approvedBy="felipe" IM.tables_requiresApprovalFor="GgImagineBatch" IM.taxonomicNames_approvedBy="felipe" IM.treatmentCitations_approvedBy="felipe" IM.treatments_approvedBy="felipe" checkinTime="1727811772558" checkinUser="felipe" docAuthor="Romanov, Roman E., Nikulin, Vyacheslav Yu., Yeo, Regina S. W., Ho, Boon-Chuan &amp; Gontcharov, Andrey A." docDate="2020" docId="DA6E8786FFB1FFA9A1E36751FB09FE88" docLanguage="en" docName="phytotaxa.438.2.2.pdf" docOrigin="Phytotaxa 438 (2)" docSource="http://dx.doi.org/10.11646/phytotaxa.438.2.2" docStyle="DocumentStyle:96748F8F1B6C902996E134952A3A36B9.13:Phytotaxa.2014-.journal_article" docStyleId="96748F8F1B6C902996E134952A3A36B9" docStyleName="Phytotaxa.2014-.journal_article" docStyleVersion="13" docTitle="Nitella singaporensis R. E. Romanov, R. S. W. Yeo, B. C. Ho, V. Yu. Nikulin &amp; A. A. Gontcharov 2020, sp. nov." docType="treatment" docVersion="2" lastPageNumber="86" masterDocId="2657FFFEFFB0FFAFA16B602DFF94FFE4" masterDocTitle="Nitella singaporensis (Charophyceae, Charales): new species and implications for the taxonomy of the genus Nitella" masterLastPageNumber="94" masterPageNumber="80" pageNumber="81" updateTime="1727812585758" updateUser="ExternalLinkService" zenodo-license-figures="UNSPECIFIED" zenodo-license-treatments="UNSPECIFIED">
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<mods:title id="458B2256637AC7EB54C465D11508B97A">Nitella singaporensis (Charophyceae, Charales): new species and implications for the taxonomy of the genus Nitella</mods:title>
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<mods:namePart id="0C9EA25567B95B09F2DD10791CBC56B7">Yeo, Regina S. W.</mods:namePart>
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<mods:affiliation id="F7A047EA31EFB93E6639ABA31BDEA8EC">Graduate School of Integrated Sciences for Life, Hiroshima University, 1 - 4 - 4 Kagamiyama, Higashi-Hiroshima, 739 - 8528, Japan</mods:affiliation>
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<mods:namePart id="C749865050C4AE7B28C0E93A6B2F0946">Ho, Boon-Chuan</mods:namePart>
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<mods:affiliation id="DA67FD1605859535649660DBC66028BB">Singapore Botanic Gardens, National Parks Board, 1 Cluny Road, Singapore, 259569, Republic of Singapore</mods:affiliation>
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<mods:namePart id="328512E8516BCAA1DE0C46C890E6C054">Gontcharov, Andrey A.</mods:namePart>
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<taxonomicName id="95C74D13FFB1FFAEA1E36751FB3FF872" authority="R.E. Romanov, R.S.W. Yeo, B.C. Ho, V.Yu. Nikulin &amp; A.A. Gontcharov" authorityName="R. E. Romanov, R. S. W. Yeo, B. C. Ho, V. Yu. Nikulin &amp; A. A. Gontcharov" authorityYear="2020" box="[136,1195,1916,1943]" class="Charophyceae" family="Characeae" genus="Nitella" kingdom="Plantae" order="Charales" pageId="1" pageNumber="81" phylum="Charophyta" rank="species" species="singaporensis" status="sp. nov.">
<emphasis id="60B3EA82FFB1FFAEA1E36751FEE8F872" bold="true" box="[136,380,1916,1943]" italics="true" pageId="1" pageNumber="81">Nitella singaporensis</emphasis>
R.E. Romanov, R.S.W. Yeo, B.C. Ho, V.Yu. Nikulin &amp; A.A. Gontcharov
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<taxonomicNameLabel id="7B8057F9FFB1FFAEA5D86751FA9DF872" box="[1203,1289,1916,1942]" pageId="1" pageNumber="81" rank="species">sp. nov.</taxonomicNameLabel>
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, Upper Pierce Reservoir Forest. Freshwater, edge of the Upper Pierce Reservoir, depth of c.
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,
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Ho,
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., Yong,
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.
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., Liew, D. &amp; Aung Thame
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2018-407
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(holo
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, iso
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).
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:
<emphasis id="60B3EA82FFB1FFAEA51B67C1FB08F7E5" box="[1136,1180,2028,2049]" italics="true" pageId="1" pageNumber="81">ibid.</emphasis>
,
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,
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Yeo,
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.
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.
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. &amp; Ho,
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. 18-071
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(
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,
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also in spirit). Det.
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<collectionCode id="34D6AE55FFB1FFAEA3E1683DFD0FF7C1" box="[650,667,2064,2085]" country="Chile" name="Departamento de Geologia, Universidad de Chile" pageId="1" pageNumber="81">R</collectionCode>
. Romanov
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. (
<figureCitation id="CAFC2A15FFB1FFAEA278683DFCDEF7C1" box="[787,842,2064,2086]" captionStart="FIGURE 14" captionStartId="2.[136,229,1827,1849]" captionTargetBox="[182,1411,386,1799]" captionTargetId="figure-120@2.[177,1411,386,1799]" captionTargetPageId="2" captionText="FIGURE 14. General appearance and whorl and branchlet of Nitella singaporensis: 1—pressed and dried material (holotype: SING); 2—pressed and dried material (isotype: LE); 3—reconstruction of general habit of branchlet whorl (view from above) from the photo of ethanol-fixed specimen (isotype: LE) showing mean of terms used for branchlet description: 1—primary ray, 2—lateral secondary ray, 3—central secondary ray, 4—lateral tertiary ray, 5—central tertiary ray, 6—dactyls, yellow—lateral secondary segments, green—central secondary segment, blue—central tertiary segment, orange—lateral tertiary segment; 4—fertile branchlet of rewetted herbarium specimen showing oogonia arrangement (isotype: LE). Scale: 1 mm. Scale: 2—1 cm, 4—1 mm. Photo 1 by D. Liew, drawing and other photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872384" httpUri="https://zenodo.org/record/13872384/files/figure.png" pageId="1" pageNumber="81">Fig. 1</figureCitation>
).
</paragraph>
<paragraph id="52783690FFB2FFADA1E360B3FF6FFE89" blockId="2.[136,1452,158,365]" pageId="2" pageNumber="82">
Description:—The plants monoecious, multiaxial from the base (
<figureCitation id="CAFC2A15FFB2FFADA23C60B3FC20FF5C" box="[855,948,158,184]" captionStart="FIGURE 14" captionStartId="2.[136,229,1827,1849]" captionTargetBox="[182,1411,386,1799]" captionTargetId="figure-120@2.[177,1411,386,1799]" captionTargetPageId="2" captionText="FIGURE 14. General appearance and whorl and branchlet of Nitella singaporensis: 1—pressed and dried material (holotype: SING); 2—pressed and dried material (isotype: LE); 3—reconstruction of general habit of branchlet whorl (view from above) from the photo of ethanol-fixed specimen (isotype: LE) showing mean of terms used for branchlet description: 1—primary ray, 2—lateral secondary ray, 3—central secondary ray, 4—lateral tertiary ray, 5—central tertiary ray, 6—dactyls, yellow—lateral secondary segments, green—central secondary segment, blue—central tertiary segment, orange—lateral tertiary segment; 4—fertile branchlet of rewetted herbarium specimen showing oogonia arrangement (isotype: LE). Scale: 1 mm. Scale: 2—1 cm, 4—1 mm. Photo 1 by D. Liew, drawing and other photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872384" httpUri="https://zenodo.org/record/13872384/files/figure.png" pageId="2" pageNumber="82">Fig. 1, 2</figureCitation>
), transparent, brilliantly green, not encrusted,
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in height, with mucilage at the apices (
<figureCitation id="CAFC2A15FFB2FFADA3D360EFFCE2FF38" box="[696,886,194,221]" captionStart="FIGURES 519" captionStartId="3.[136,243,1659,1681]" captionTargetBox="[215,1371,190,1635]" captionTargetId="figure-22@3.[215,1371,190,1635]" captionTargetPageId="3" captionText="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872388" httpUri="https://zenodo.org/record/13872388/files/figure.png" pageId="2" pageNumber="82">Figs. 5, 8, 1216</figureCitation>
) and rhizoids originating from lowest stem nodes. The mucilage covers both the branchlets and stem. Obvious heads are not formed although subtle condensation of uppermost whorls can be noted (
<figureCitation id="CAFC2A15FFB2FFADA09F6127FDACFEC1" box="[500,568,266,293]" captionStart="FIGURES 519" captionStartId="3.[136,243,1659,1681]" captionTargetBox="[215,1371,190,1635]" captionTargetId="figure-22@3.[215,1371,190,1635]" captionTargetPageId="3" captionText="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872388" httpUri="https://zenodo.org/record/13872388/files/figure.png" pageId="2" pageNumber="82">Fig. 5</figureCitation>
). The stem is slender, 270420 μm in diameter. The internodes slightly shorter, longer (up to 1.5 times) or nearly equal to the branchlets in upper parts and 11.5(2)-times longer in lower ones (
<figureCitation id="CAFC2A15FFB2FFADA41F6103FF20FE88" captionStart="FIGURE 14" captionStartId="2.[136,229,1827,1849]" captionTargetBox="[182,1411,386,1799]" captionTargetId="figure-120@2.[177,1411,386,1799]" captionTargetPageId="2" captionText="FIGURE 14. General appearance and whorl and branchlet of Nitella singaporensis: 1—pressed and dried material (holotype: SING); 2—pressed and dried material (isotype: LE); 3—reconstruction of general habit of branchlet whorl (view from above) from the photo of ethanol-fixed specimen (isotype: LE) showing mean of terms used for branchlet description: 1—primary ray, 2—lateral secondary ray, 3—central secondary ray, 4—lateral tertiary ray, 5—central tertiary ray, 6—dactyls, yellow—lateral secondary segments, green—central secondary segment, blue—central tertiary segment, orange—lateral tertiary segment; 4—fertile branchlet of rewetted herbarium specimen showing oogonia arrangement (isotype: LE). Scale: 1 mm. Scale: 2—1 cm, 4—1 mm. Photo 1 by D. Liew, drawing and other photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872384" httpUri="https://zenodo.org/record/13872384/files/figure.png" pageId="2" pageNumber="82">Figs. 1, 2</figureCitation>
,
<figureCitation id="CAFC2A15FFB2FFADA1AB617FFF7AFE89" box="[192,238,338,365]" captionStart="FIGURES 519" captionStartId="3.[136,243,1659,1681]" captionTargetBox="[215,1371,190,1635]" captionTargetId="figure-22@3.[215,1371,190,1635]" captionTargetPageId="3" captionText="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872388" httpUri="https://zenodo.org/record/13872388/files/figure.png" pageId="2" pageNumber="82">57</figureCitation>
).
</paragraph>
<caption id="06B86618FFB2FFADA1E3670EFE93F7F5" ID-DOI="http://doi.org/10.5281/zenodo.13872384" ID-Zenodo-Dep="13872384" httpUri="https://zenodo.org/record/13872384/files/figure.png" pageId="2" pageNumber="82" startId="2.[136,229,1827,1849]" targetBox="[182,1411,386,1799]" targetPageId="2" targetType="figure">
<paragraph id="52783690FFB2FFADA1E3670EFE93F7F5" blockId="2.[136,1452,1827,2065]" pageId="2" pageNumber="82">
<emphasis id="60B3EA82FFB2FFADA1E3670EFE83F8DC" bold="true" box="[136,279,1827,1849]" pageId="2" pageNumber="82">FIGURE 14.</emphasis>
General appearance and whorl and branchlet of
<taxonomicName id="95C74D13FFB2FFADA39F670EFC54F8DD" authorityName="R. E. Romanov, R. S. W. Yeo, B. C. Ho, V. Yu. Nikulin &amp; A. A. Gontcharov" authorityYear="2020" box="[756,960,1827,1849]" class="Charophyceae" family="Characeae" genus="Nitella" kingdom="Plantae" order="Charales" pageId="2" pageNumber="82" phylum="Charophyta" rank="species" species="singaporensis">
<emphasis id="60B3EA82FFB2FFADA39F670EFC54F8DD" box="[756,960,1827,1849]" italics="true" pageId="2" pageNumber="82">Nitella singaporensis</emphasis>
</taxonomicName>
: 1—pressed and dried material (holotype: SING); 2—pressed and dried material (isotype: LE); 3—reconstruction of general habit of branchlet whorl (view from above) from the photo of ethanol-fixed specimen (isotype: LE) showing mean of terms used for branchlet description: 1—primary ray, 2—lateral secondary ray, 3—central secondary ray, 4—lateral tertiary ray, 5—central tertiary ray, 6—dactyls, yellow—lateral secondary segments, green—central secondary segment, blue—central tertiary segment, orange—lateral tertiary segment; 4—fertile branchlet of rewetted herbarium specimen showing oogonia arrangement (isotype: LE). Scale: 1 mm. Scale: 2—1 cm, 4—1 mm. Photo 1 by D. Liew, drawing and other photos by R. Romanov.
</paragraph>
</caption>
<caption id="06B86618FFB3FFACA1E36656FA08F81C" ID-DOI="http://doi.org/10.5281/zenodo.13872388" ID-Zenodo-Dep="13872388" httpUri="https://zenodo.org/record/13872388/files/figure.png" pageId="3" pageNumber="83" startId="3.[136,243,1659,1681]" targetBox="[215,1371,190,1635]" targetPageId="3" targetType="figure">
<paragraph id="52783690FFB3FFACA1E36656FA08F81C" blockId="3.[136,1452,1659,2041]" pageId="3" pageNumber="83">
<emphasis id="60B3EA82FFB3FFACA1E36656FEA4F974" bold="true" box="[136,304,1659,1681]" pageId="3" pageNumber="83">FIGURES 519.</emphasis>
The whorls and branchlets of
<taxonomicName id="95C74D13FFB3FFACA30A6656FCBAF975" authorityName="R. E. Romanov, R. S. W. Yeo, B. C. Ho, V. Yu. Nikulin &amp; A. A. Gontcharov" authorityYear="2020" box="[609,814,1659,1681]" class="Charophyceae" family="Characeae" genus="Nitella" kingdom="Plantae" order="Charales" pageId="3" pageNumber="83" phylum="Charophyta" rank="species" species="singaporensis">
<emphasis id="60B3EA82FFB3FFACA30A6656FCBAF975" box="[609,814,1659,1681]" italics="true" pageId="3" pageNumber="83">Nitella singaporensis</emphasis>
</taxonomicName>
(all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm. All photos by R. Romanov.
</paragraph>
</caption>
<caption id="06B86618FFB4FFABA1E365F7FC38F908" ID-DOI="http://doi.org/10.5281/zenodo.13872390" ID-Zenodo-Dep="13872390" httpUri="https://zenodo.org/record/13872390/files/figure.png" pageId="4" pageNumber="84" startId="4.[136,243,1498,1520]" targetBox="[151,1436,190,1474]" targetPageId="4" targetType="figure">
<paragraph id="52783690FFB4FFABA1E365F7FC38F908" blockId="4.[136,1452,1498,1772]" pageId="4" pageNumber="84">
<emphasis id="60B3EA82FFB4FFABA1E365F7FEAEFA0B" bold="true" box="[136,314,1498,1520]" pageId="4" pageNumber="84">FIGURES 2031.</emphasis>
<taxonomicName id="95C74D13FFB4FFABA05465F7FD9EFA14" authorityName="R. E. Romanov, R. S. W. Yeo, B. C. Ho, V. Yu. Nikulin &amp; A. A. Gontcharov" authorityYear="2020" box="[319,522,1498,1520]" class="Charophyceae" family="Characeae" genus="Nitella" kingdom="Plantae" order="Charales" pageId="4" pageNumber="84" phylum="Charophyta" rank="species" species="singaporensis">
<emphasis id="60B3EA82FFB4FFABA05465F7FD9EFA14" box="[319,522,1498,1520]" italics="true" pageId="4" pageNumber="84">Nitella singaporensis</emphasis>
</taxonomicName>
from Singapore (isotype: LE),
<taxonomicName id="95C74D13FFB4FFABA25F65F6FC0CFA0B" authorityName="C. Agardh" authorityYear="1824" baseAuthorityName="J. Sm." box="[820,920,1498,1520]" class="Charophyceae" family="Characeae" genus="Nitella" kingdom="Plantae" order="Charales" pageId="4" pageNumber="84" phylum="Charophyta" rank="species" species="gracilis">
<emphasis id="60B3EA82FFB4FFABA25F65F6FC0CFA0B" box="[820,920,1498,1520]" italics="true" pageId="4" pageNumber="84">N. gracilis</emphasis>
</taxonomicName>
from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of
<taxonomicName id="95C74D13FFB4FFABA051669EFE0AF923" authorityName="C. Agardh" authorityYear="1824" baseAuthorityName="J. Sm." box="[314,414,1714,1736]" class="Charophyceae" family="Characeae" genus="Nitella" kingdom="Plantae" order="Charales" pageId="4" pageNumber="84" phylum="Charophyta" rank="species" species="gracilis">
<emphasis id="60B3EA82FFB4FFABA051669EFE0AF923" box="[314,414,1714,1736]" italics="true" pageId="4" pageNumber="84">N. gracilis</emphasis>
</taxonomicName>
with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo.
</paragraph>
</caption>
<paragraph id="52783690FFB4FFABA1D66736FD34F845" blockId="4.[136,1452,1819,2061]" pageId="4" pageNumber="84">
The notable cells are visible at the lowest stem nodes. They are formed in double number in comparison with branchlet ones (
<figureCitation id="CAFC2A15FFB4FFABA0556712FE5CF8BD" box="[318,456,1855,1881]" captionStart="FIGURES 2031" captionStartId="4.[136,243,1498,1520]" captionTargetBox="[151,1436,190,1474]" captionTargetId="figure-19@4.[151,1436,190,1474]" captionTargetPageId="4" captionText="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi="http://doi.org/10.5281/zenodo.13872390" httpUri="https://zenodo.org/record/13872390/files/figure.png" pageId="4" pageNumber="84">Figs. 2830</figureCitation>
). They are merely result of the protrusion of nodal cells at the base of a branchlet in all directions because of node enlargement which is culminating in nodal bulbil formation at the lowest part of the thallus (
<figureCitation id="CAFC2A15FFB4FFABA1FA67AAFF71F845" box="[145,229,1927,1953]" captionStart="FIGURES 2031" captionStartId="4.[136,243,1498,1520]" captionTargetBox="[151,1436,190,1474]" captionTargetId="figure-19@4.[151,1436,190,1474]" captionTargetPageId="4" captionText="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi="http://doi.org/10.5281/zenodo.13872390" httpUri="https://zenodo.org/record/13872390/files/figure.png" pageId="4" pageNumber="84">Fig. 30</figureCitation>
). The bulbils are up to 1.04 ×
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.
</paragraph>
<paragraph id="52783690FFB4FFAAA1D66786FB3DFEC0" blockId="4.[136,1452,1819,2061]" lastBlockId="5.[136,1452,158,2093]" lastPageId="5" lastPageNumber="85" pageId="4" pageNumber="84">
The sterile and fertile branchlets are similar in principal arrangement, but the former usually are longer and have more lax appearance in contrast with the more or less and finally clearly abbreviated secondary and tertiary rays of fertile branchlets. This results in the compact habit of terminal branchlet parts. The sterile branchlets are situated in the lower part of a plant. The branchlets are arranged in uniform whorls of 6 or 8, rarely 7,
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long, macrodactylous, 23-times furcate but never 1- or 4-furcated (
<figureCitation id="CAFC2A15FFB5FFAAA22D60EFFC00FF38" box="[838,916,194,220]" captionStart="FIGURE 14" captionStartId="2.[136,229,1827,1849]" captionTargetBox="[182,1411,386,1799]" captionTargetId="figure-120@2.[177,1411,386,1799]" captionTargetPageId="2" captionText="FIGURE 14. General appearance and whorl and branchlet of Nitella singaporensis: 1—pressed and dried material (holotype: SING); 2—pressed and dried material (isotype: LE); 3—reconstruction of general habit of branchlet whorl (view from above) from the photo of ethanol-fixed specimen (isotype: LE) showing mean of terms used for branchlet description: 1—primary ray, 2—lateral secondary ray, 3—central secondary ray, 4—lateral tertiary ray, 5—central tertiary ray, 6—dactyls, yellow—lateral secondary segments, green—central secondary segment, blue—central tertiary segment, orange—lateral tertiary segment; 4—fertile branchlet of rewetted herbarium specimen showing oogonia arrangement (isotype: LE). Scale: 1 mm. Scale: 2—1 cm, 4—1 mm. Photo 1 by D. Liew, drawing and other photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872384" httpUri="https://zenodo.org/record/13872384/files/figure.png" pageId="5" pageNumber="85">Figs. 3</figureCitation>
,
<figureCitation id="CAFC2A15FFB5FFAAA2CA60EFFC49FF38" box="[929,989,194,220]" captionStart-0="FIGURES 519" captionStart-1="FIGURES 2031" captionStartId-0="3.[136,243,1659,1681]" captionStartId-1="4.[136,243,1498,1520]" captionTargetBox-0="[215,1371,190,1635]" captionTargetBox-1="[151,1436,190,1474]" captionTargetId-0="figure-22@3.[215,1371,190,1635]" captionTargetId-1="figure-19@4.[151,1436,190,1474]" captionTargetPageId-0="3" captionTargetPageId-1="4" captionText-0="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." captionText-1="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi-0="http://doi.org/10.5281/zenodo.13872388" figureDoi-1="http://doi.org/10.5281/zenodo.13872390" httpUri-0="https://zenodo.org/record/13872388/files/figure.png" httpUri-1="https://zenodo.org/record/13872390/files/figure.png" pageId="5" pageNumber="85">722</figureCitation>
). The primary ray is
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long, 86172 μm across. The longest is ca. ½ of branchlet length or usually slightly longer at lower parts but increasing in relative length towards apex from ca. ½ to 3/5 and 2/3, i.e. 0.370.74 of total branchlet length.
</paragraph>
<paragraph id="52783690FFB5FFAAA1D66103FE9FFD1D" blockId="5.[136,1452,158,2093]" pageId="5" pageNumber="85">
The lateral secondary rays are mainly 5 and 6, but 4, 7 and even 8 occur exceptionally.
<collectionCode id="34D6AE55FFB5FFAAA5F46103FB26FEAC" box="[1183,1202,302,328]" country="USA" lsid="urn:lsid:biocol.org:col:15406" name="Harvard University - Arnold Arboretum" pageId="5" pageNumber="85" type="Herbarium">A</collectionCode>
central secondary ray is also present (
<figureCitation id="CAFC2A15FFB5FFAAA02A617FFE2BFE88" box="[321,447,338,364]" captionStart-0="FIGURES 519" captionStart-1="FIGURES 2031" captionStartId-0="3.[136,243,1659,1681]" captionStartId-1="4.[136,243,1498,1520]" captionTargetBox-0="[215,1371,190,1635]" captionTargetBox-1="[151,1436,190,1474]" captionTargetId-0="figure-22@3.[215,1371,190,1635]" captionTargetId-1="figure-19@4.[151,1436,190,1474]" captionTargetPageId-0="3" captionTargetPageId-1="4" captionText-0="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." captionText-1="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi-0="http://doi.org/10.5281/zenodo.13872388" figureDoi-1="http://doi.org/10.5281/zenodo.13872390" httpUri-0="https://zenodo.org/record/13872388/files/figure.png" httpUri-1="https://zenodo.org/record/13872390/files/figure.png" pageId="5" pageNumber="85">Figs. 722</figureCitation>
). The lateral secondary segments are commonly once-forked (
<figureCitation id="CAFC2A15FFB5FFAAA5FE617FFAD5FE88" box="[1173,1345,338,364]" captionStart="FIGURES 519" captionStartId="3.[136,243,1659,1681]" captionTargetBox="[215,1371,190,1635]" captionTargetId="figure-22@3.[215,1371,190,1635]" captionTargetPageId="3" captionText="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872388" httpUri="https://zenodo.org/record/13872388/files/figure.png" pageId="5" pageNumber="85">Figs. 9, 14, 16</figureCitation>
,
<figureCitation id="CAFC2A15FFB5FFAAA43A617FFAFBFE88" box="[1361,1391,338,364]" captionStart="FIGURES 2031" captionStartId="4.[136,243,1498,1520]" captionTargetBox="[151,1436,190,1474]" captionTargetId="figure-19@4.[151,1436,190,1474]" captionTargetPageId="4" captionText="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi="http://doi.org/10.5281/zenodo.13872390" httpUri="https://zenodo.org/record/13872390/files/figure.png" pageId="5" pageNumber="85">21</figureCitation>
), but may also be 12-times forked (
<figureCitation id="CAFC2A15FFB5FFAAA087615BFDFEFE75" box="[492,618,374,401]" captionStart="FIGURES 519" captionStartId="3.[136,243,1659,1681]" captionTargetBox="[215,1371,190,1635]" captionTargetId="figure-22@3.[215,1371,190,1635]" captionTargetPageId="3" captionText="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872388" httpUri="https://zenodo.org/record/13872388/files/figure.png" pageId="5" pageNumber="85">Fig. 12, 15</figureCitation>
,
<figureCitation id="CAFC2A15FFB5FFAAA31C615BFD03FE74" box="[631,663,374,400]" captionStart="FIGURES 2031" captionStartId="4.[136,243,1498,1520]" captionTargetBox="[151,1436,190,1474]" captionTargetId="figure-19@4.[151,1436,190,1474]" captionTargetPageId="4" captionText="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi="http://doi.org/10.5281/zenodo.13872390" httpUri="https://zenodo.org/record/13872390/files/figure.png" pageId="5" pageNumber="85">22</figureCitation>
). One or even 3 lateral secondary rays can be unforked as exceptions (
<figureCitation id="CAFC2A15FFB5FFAAA1FA61B7FF71FE50" box="[145,229,410,436]" captionStart="FIGURES 519" captionStartId="3.[136,243,1659,1681]" captionTargetBox="[215,1371,190,1635]" captionTargetId="figure-22@3.[215,1371,190,1635]" captionTargetPageId="3" captionText="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872388" httpUri="https://zenodo.org/record/13872388/files/figure.png" pageId="5" pageNumber="85">Fig. 17</figureCitation>
, arrowheads). In case of single furcation, (4)5(6) equal dactyls (in other words, end lateral tertiary rays) surrounding 0 or 1 central dactyl are produced. In case of 2-times furcation, which usually does not form in all lateral secondary segments on the same branchlet (04 among 47 ones), two variants of third (distal) furcation are possible within the same branchlet. In the first variant, which is more common, there is absence of central dactyl and formation of 4 once-furcated lateral tertiary segments producing (3)45 equal dactyls at the furcation (
<figureCitation id="CAFC2A15FFB5FFAAA5CD6207FB6DFDA0" box="[1190,1273,554,580]" captionStart="FIGURES 519" captionStartId="3.[136,243,1659,1681]" captionTargetBox="[215,1371,190,1635]" captionTargetId="figure-22@3.[215,1371,190,1635]" captionTargetPageId="3" captionText="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872388" httpUri="https://zenodo.org/record/13872388/files/figure.png" pageId="5" pageNumber="85">Fig. 13</figureCitation>
). In the second, which is rarer, there is a formation of central dactyl (in other words, end unforked central tertiary ray) surrounded with 5 lateral dactyls (i.e. end lateral quaternary rays). The lateral tertiary rays are shorter than dactyls, i.e. less than 1/3 of their length, ca. 0.8 to 2-times shorter. The central dactyl is formed at sterile nodes only, i.e. it is produced instead of antheridium. Therefore, the dactyls of secondary lateral segments range from
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number, one of them can be central one.
</paragraph>
<paragraph id="52783690FFB5FFAAA1D6632FFC1EFB61" blockId="5.[136,1452,158,2093]" pageId="5" pageNumber="85">
The central secondary ray may be short, resulting in a small length of this part of a branchlet shorter than surrounding lateral secondary segments and nearly hidden with them (
<figureCitation id="CAFC2A15FFB5FFAAA2F2630BFC72FCA4" box="[921,998,806,832]" captionStart="FIGURE 14" captionStartId="2.[136,229,1827,1849]" captionTargetBox="[182,1411,386,1799]" captionTargetId="figure-120@2.[177,1411,386,1799]" captionTargetPageId="2" captionText="FIGURE 14. General appearance and whorl and branchlet of Nitella singaporensis: 1—pressed and dried material (holotype: SING); 2—pressed and dried material (isotype: LE); 3—reconstruction of general habit of branchlet whorl (view from above) from the photo of ethanol-fixed specimen (isotype: LE) showing mean of terms used for branchlet description: 1—primary ray, 2—lateral secondary ray, 3—central secondary ray, 4—lateral tertiary ray, 5—central tertiary ray, 6—dactyls, yellow—lateral secondary segments, green—central secondary segment, blue—central tertiary segment, orange—lateral tertiary segment; 4—fertile branchlet of rewetted herbarium specimen showing oogonia arrangement (isotype: LE). Scale: 1 mm. Scale: 2—1 cm, 4—1 mm. Photo 1 by D. Liew, drawing and other photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872384" httpUri="https://zenodo.org/record/13872384/files/figure.png" pageId="5" pageNumber="85">Figs. 4</figureCitation>
,
<figureCitation id="CAFC2A15FFB5FFAAA299630BFBAFFCA4" box="[1010,1083,806,832]" captionStart-0="FIGURES 519" captionStart-1="FIGURES 2031" captionStartId-0="3.[136,243,1659,1681]" captionStartId-1="4.[136,243,1498,1520]" captionTargetBox-0="[215,1371,190,1635]" captionTargetBox-1="[151,1436,190,1474]" captionTargetId-0="figure-22@3.[215,1371,190,1635]" captionTargetId-1="figure-19@4.[151,1436,190,1474]" captionTargetPageId-0="3" captionTargetPageId-1="4" captionText-0="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." captionText-1="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi-0="http://doi.org/10.5281/zenodo.13872388" figureDoi-1="http://doi.org/10.5281/zenodo.13872390" httpUri-0="https://zenodo.org/record/13872388/files/figure.png" httpUri-1="https://zenodo.org/record/13872390/files/figure.png" pageId="5" pageNumber="85">1821</figureCitation>
), especially if they are adpressed (
<figureCitation id="CAFC2A15FFB5FFAAA1FA6367FF72FC80" box="[145,230,842,868]" captionStart="FIGURES 519" captionStartId="3.[136,243,1659,1681]" captionTargetBox="[215,1371,190,1635]" captionTargetId="figure-22@3.[215,1371,190,1635]" captionTargetPageId="3" captionText="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872388" httpUri="https://zenodo.org/record/13872388/files/figure.png" pageId="5" pageNumber="85">Fig. 19</figureCitation>
). As such, the branchlet is tassel-like in general appearance (
<figureCitation id="CAFC2A15FFB5FFAAA2C36367FC69FC80" box="[936,1021,842,868]" captionStart="FIGURES 519" captionStartId="3.[136,243,1659,1681]" captionTargetBox="[215,1371,190,1635]" captionTargetId="figure-22@3.[215,1371,190,1635]" captionTargetPageId="3" captionText="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872388" httpUri="https://zenodo.org/record/13872388/files/figure.png" pageId="5" pageNumber="85">Fig. 19</figureCitation>
). In one instance, abbreviated central secondary ray resulted in the appearance of the whole central secondary segment as an accessory branchlet (
<figureCitation id="CAFC2A15FFB5FFAAA4216343FF33FC48" captionStart="FIGURES 2031" captionStartId="4.[136,243,1498,1520]" captionTargetBox="[151,1436,190,1474]" captionTargetId="figure-19@4.[151,1436,190,1474]" captionTargetPageId="4" captionText="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi="http://doi.org/10.5281/zenodo.13872390" httpUri="https://zenodo.org/record/13872390/files/figure.png" pageId="5" pageNumber="85">Figs. 20, 21</figureCitation>
). Otherwise, they are usually longer where the central part of a branchlet is more or less extending from surrounding lateral secondary segments and looking as a branch (
<figureCitation id="CAFC2A15FFB5FFAAA380639BFCE2FC35" box="[747,886,950,977]" captionStart="FIGURES 519" captionStartId="3.[136,243,1659,1681]" captionTargetBox="[215,1371,190,1635]" captionTargetId="figure-22@3.[215,1371,190,1635]" captionTargetPageId="3" captionText="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872388" httpUri="https://zenodo.org/record/13872388/files/figure.png" pageId="5" pageNumber="85">Figs. 1015</figureCitation>
). Therefore, in these cases, the branchlets can be considered monopodial. Sometimes the central tertiary rays can be formed at upper furcation of central secondary rays (
<figureCitation id="CAFC2A15FFB5FFAAA1FA63D3FE8CFBFC" box="[145,280,1022,1048]" captionStart="FIGURES 519" captionStartId="3.[136,243,1659,1681]" captionTargetBox="[215,1371,190,1635]" captionTargetId="figure-22@3.[215,1371,190,1635]" captionTargetPageId="3" captionText="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872388" httpUri="https://zenodo.org/record/13872388/files/figure.png" pageId="5" pageNumber="85">Figs. 10, 11</figureCitation>
). They end with furcation producing 3 or 5 dactyls. The absence of node at the top of central secondary ray can occur as an exception. In this case central, the whole secondary ray becomes unusually long and robust dactyl (
<figureCitation id="CAFC2A15FFB5FFAAA1FA646BFF42FB84" box="[145,214,1094,1120]" captionStart="FIGURES 519" captionStartId="3.[136,243,1659,1681]" captionTargetBox="[215,1371,190,1635]" captionTargetId="figure-22@3.[215,1371,190,1635]" captionTargetPageId="3" captionText="FIGURES 519. The whorls and branchlets of Nitella singaporensis (all from isotype: LE): 5—apical part with mucilage recognised because of adhering of fine particles at its surface; 57—whorls of branchlets, showing long primary ray; 818—branchlets, showing variability in length of central secondary ray, from moderately elongated, i.e. exceeding the length of lateral secondary rays with their dactyls (8 &amp; 9), nearly equal with them (10, 12, 14), to abbreviated, i.e. clearly shorter than lateral second segments (19), mainly spreading (816) or adpressed to the central one, resulting in last case in tassel-like general appearance of the branchlet (19); 8, 12, 15, 16—fine particles adhered to the surface of a branchlet, indicating presence of a mucilage at its surface; actually they are outlining the mucilage patches; 9—central secondary ray without furcation, appearing as long robust dactyl (arrowheads); 10 &amp; 11—branchlets with central tertiary ray (arrowheads); 11—branchlet with central secondary ray with furcation (double arrowhead), producing central tertiary ray with 3 dactyls (arrowhead); 12—dactyls at the furcation at the top of central secondary ray (arrowhead); 13—central tertiary ray (arrowhead) at lateral secondary ray; 17—unfurcated lateral secondary rays (arrowheads), central secondary ray at the branchlet below is not clearly visible because of artificial deformation at its base. Scale: 511—2 mm, 1217—1 mm, 18 &amp; 19—0.5 mm.All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872388" httpUri="https://zenodo.org/record/13872388/files/figure.png" pageId="5" pageNumber="85">Fig. 9</figureCitation>
, arrowheads). The central secondary ray is up to
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in length or significantly shorter than lateral ones. Usually it is somewhat stouter in comparison with lateral ones.
</paragraph>
<paragraph id="52783690FFB5FFAAA1D664A3FC2EFAB8" blockId="5.[136,1452,158,2093]" pageId="5" pageNumber="85">
The lateral tertiary rays at the top of central secondary ray are 5 or
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number. They can be obviously shortened in the same way as in lateral secondary rays as described above, with 0.5 of dactyls length. The lateral tertiary segments at central secondary ray may produce a node furcating in 4 or 5 dactyls, or can be nodeless (i.e. they are 5 or 6 dactyls themselves) in the same branchlet. The 15 of 5 lateral tertiary rays can ends with furcation. In this case the whole tertiary segment is nearly equal or somewhat longer than dactyls from the same node. In the last case dactyls of the third furcation are obviously shorter than dactyls of second furcation.
</paragraph>
<paragraph id="52783690FFB5FFAAA1D6654BFA82FA40" blockId="5.[136,1452,158,2093]" pageId="5" pageNumber="85">
The lateral secondary rays are
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in length; the central tertiary ones (if present) are
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; the lateral tertiary ones (if present) are
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; the dactyls are (0.39)0.641.3(1.65) mm in length.
</paragraph>
<paragraph id="52783690FFB5FFAAA1D66583FDABF945" blockId="5.[136,1452,158,2093]" pageId="5" pageNumber="85">
Dactyls are constantly two-celled (
<figureCitation id="CAFC2A15FFB5FFAAA3236583FD45FA2D" box="[584,721,1454,1481]" captionStart="FIGURES 2031" captionStartId="4.[136,243,1498,1520]" captionTargetBox="[151,1436,190,1474]" captionTargetId="figure-19@4.[151,1436,190,1474]" captionTargetPageId="4" captionText="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi="http://doi.org/10.5281/zenodo.13872390" httpUri="https://zenodo.org/record/13872390/files/figure.png" pageId="5" pageNumber="85">Figs. 2325</figureCitation>
), mostly clearly uniform, equal to each other, never abbreviated, with small conical end cell, which seems to be decaying after short-term storage in the laboratory. The first furcation of a branchlet usually does not
<taxonomicName id="95C74D13FFB5FFAAA08965DBFDE5F9F4" box="[482,625,1526,1552]" form="dactyls" pageId="5" pageNumber="85" rank="form">form dactyls</taxonomicName>
, they are present at second and third furcations generally. The penultimate cell of a dactyl is cylindrical shortly pointed at the apex; therefore, its apex does not differ with the apex of end cell with width (
<figureCitation id="CAFC2A15FFB5FFAAA0656613FE01F9BD" box="[270,405,1598,1625]" captionStart="FIGURES 2031" captionStartId="4.[136,243,1498,1520]" captionTargetBox="[151,1436,190,1474]" captionTargetId="figure-19@4.[151,1436,190,1474]" captionTargetPageId="4" captionText="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi="http://doi.org/10.5281/zenodo.13872390" httpUri="https://zenodo.org/record/13872390/files/figure.png" pageId="5" pageNumber="85">Figs. 23, 25</figureCitation>
), (37)5796(104) μm width. Terminal (i.e. end) cell is confluent, but is small in comparison with the adjacent penultimate cell, 7191 × 2027 μm (rewetted), its apex pointed and mostly clearly thickened. Its thickness varies within (4.3)623 μm.
</paragraph>
<paragraph id="52783690FFB5FFAAA1D66687FE7AF7C8" blockId="5.[136,1452,158,2093]" pageId="5" pageNumber="85">
The gametangia are never formed at the base of the whorls and first furcation (because of constant formation of central secondary ray), or at furcation with central ray. In other words, the nodes with gametangia do not
<taxonomicName id="95C74D13FFB5FFAAA44966E3FA3FF90C" box="[1314,1451,1742,1768]" form="central" pageId="5" pageNumber="85" rank="form">form central</taxonomicName>
ray. Gametangia conjoined, but the samples studied have prevalence of dichogamous (?) nodes. Nodes with single oogonium and even single antheridium are found but it is uncertain without studying its different developmental stages if they were produced without their counterparts, or always together but the antheridia have already fallen at the time of sampling. Both antheridia and oogonia are solitary, not geminate, mainly at the terminal furcations (
<figureCitation id="CAFC2A15FFB5FFAAA5946773FAD6F89C" box="[1279,1346,1886,1912]" captionStart="FIGURE 14" captionStartId="2.[136,229,1827,1849]" captionTargetBox="[182,1411,386,1799]" captionTargetId="figure-120@2.[177,1411,386,1799]" captionTargetPageId="2" captionText="FIGURE 14. General appearance and whorl and branchlet of Nitella singaporensis: 1—pressed and dried material (holotype: SING); 2—pressed and dried material (isotype: LE); 3—reconstruction of general habit of branchlet whorl (view from above) from the photo of ethanol-fixed specimen (isotype: LE) showing mean of terms used for branchlet description: 1—primary ray, 2—lateral secondary ray, 3—central secondary ray, 4—lateral tertiary ray, 5—central tertiary ray, 6—dactyls, yellow—lateral secondary segments, green—central secondary segment, blue—central tertiary segment, orange—lateral tertiary segment; 4—fertile branchlet of rewetted herbarium specimen showing oogonia arrangement (isotype: LE). Scale: 1 mm. Scale: 2—1 cm, 4—1 mm. Photo 1 by D. Liew, drawing and other photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872384" httpUri="https://zenodo.org/record/13872384/files/figure.png" pageId="5" pageNumber="85">Fig. 4</figureCitation>
,
<figureCitation id="CAFC2A15FFB5FFAAA4256773FAFAF89C" box="[1358,1390,1886,1912]" captionStart="FIGURES 2031" captionStartId="4.[136,243,1498,1520]" captionTargetBox="[151,1436,190,1474]" captionTargetId="figure-19@4.[151,1436,190,1474]" captionTargetPageId="4" captionText="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi="http://doi.org/10.5281/zenodo.13872390" httpUri="https://zenodo.org/record/13872390/files/figure.png" pageId="5" pageNumber="85">26</figureCitation>
). The formation of antheridium on penultimate furcations has been found as a rare case too (
<figureCitation id="CAFC2A15FFB5FFAAA50967AFFB23F878" box="[1122,1207,1922,1948]" captionStart="FIGURES 2031" captionStartId="4.[136,243,1498,1520]" captionTargetBox="[151,1436,190,1474]" captionTargetId="figure-19@4.[151,1436,190,1474]" captionTargetPageId="4" captionText="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi="http://doi.org/10.5281/zenodo.13872390" httpUri="https://zenodo.org/record/13872390/files/figure.png" pageId="5" pageNumber="85">Fig. 26</figureCitation>
). The oogonia can be produced at the second and mostly at the third and the fourth furcations of the branchlet, i.e. from the node at the top of lateral secondary ray in case of absence of central tertiary ray, or at the end furcations of central and lateral secondary segments. The antheridia are found on the youngest branchlets, they are shortly stipitate and nearly equal in appearance to conjoining oogonia (
<figureCitation id="CAFC2A15FFB5FFAAA0E5683FFE76F7C8" box="[398,482,2066,2092]" captionStart="FIGURES 2031" captionStartId="4.[136,243,1498,1520]" captionTargetBox="[151,1436,190,1474]" captionTargetId="figure-19@4.[151,1436,190,1474]" captionTargetPageId="4" captionText="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi="http://doi.org/10.5281/zenodo.13872390" httpUri="https://zenodo.org/record/13872390/files/figure.png" pageId="5" pageNumber="85">Fig. 26</figureCitation>
).
</paragraph>
<paragraph id="52783690FFB6FFA9A1D660B3FB09FE88" blockId="6.[136,1452,158,365]" pageId="6" pageNumber="86">
Oogonium without coronula 393429 × 329340 μm, with 78 convolutions (
<figureCitation id="CAFC2A15FFB6FFA9A57460B3FBE6FF5C" box="[1055,1138,158,184]" captionStart="FIGURES 2031" captionStartId="4.[136,243,1498,1520]" captionTargetBox="[151,1436,190,1474]" captionTargetId="figure-19@4.[151,1436,190,1474]" captionTargetPageId="4" captionText="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi="http://doi.org/10.5281/zenodo.13872390" httpUri="https://zenodo.org/record/13872390/files/figure.png" pageId="6" pageNumber="86">Fig. 26</figureCitation>
), antheridia
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in diameter. Ripe oospores are abundant, dark-brown in fixed state, but yellow-brown in transmission light and black in dry state in reflected light, 275300 × 239243 μm. The oospores have 8 low spiral ridges (
<figureCitation id="CAFC2A15FFB6FFA9A5EE60CBFA99FEE4" box="[1157,1293,230,256]" captionStart="FIGURES 3237" captionStartId="6.[136,243,1651,1673]" captionTargetBox="[177,1410,389,1626]" captionTargetId="figure-127@6.[177,1410,389,1626]" captionTargetPageId="6" captionText="FIGURES 3237. Oospores of Nitella singaporensis (isotype: LE): 32—general habit, 3337—surface ornamentation of fossa and ribs at different magnification. Scale: 32—40 μm, 33, 34—10 μm, 35—8 μm, 36—4 μm, 37—1 μm. All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872394" httpUri="https://zenodo.org/record/13872394/files/figure.png" pageId="6" pageNumber="86">Figs. 32, 33</figureCitation>
). The oospore surface sculpture is complex, appearing densely but imperfectly reticulated in light microscope (
<collectionCode id="34D6AE55FFB6FFA9A5AA6127FB7AFEC0" box="[1217,1262,266,292]" country="Mozambique" lsid="urn:lsid:biocol.org:col:13988" name="Secçáo de Botânica e Ecologia" pageId="6" pageNumber="86" type="Herbarium">LM</collectionCode>
) (
<figureCitation id="CAFC2A15FFB6FFA9A46D6127FACDFEC0" box="[1286,1369,266,292]" captionStart="FIGURES 2031" captionStartId="4.[136,243,1498,1520]" captionTargetBox="[151,1436,190,1474]" captionTargetId="figure-19@4.[151,1436,190,1474]" captionTargetPageId="4" captionText="FIGURES 2031. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 &amp; 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 2325—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 2830—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 2022—0.5 mm, 2326, 2831—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo." figureDoi="http://doi.org/10.5281/zenodo.13872390" httpUri="https://zenodo.org/record/13872390/files/figure.png" pageId="6" pageNumber="86">Fig. 27</figureCitation>
), while in the
<collectionCode id="34D6AE55FFB6FFA9A1A46103FE9DFEAC" box="[207,265,302,328]" pageId="6" pageNumber="86">SEM</collectionCode>
the reticulation is ornamented with numerous and irregularly distributed granular protrusions of different sizes (
<figureCitation id="CAFC2A15FFB6FFA9A1A4617FFEC3FE88" box="[207,343,338,364]" captionStart="FIGURES 3237" captionStartId="6.[136,243,1651,1673]" captionTargetBox="[177,1410,389,1626]" captionTargetId="figure-127@6.[177,1410,389,1626]" captionTargetPageId="6" captionText="FIGURES 3237. Oospores of Nitella singaporensis (isotype: LE): 32—general habit, 3337—surface ornamentation of fossa and ribs at different magnification. Scale: 32—40 μm, 33, 34—10 μm, 35—8 μm, 36—4 μm, 37—1 μm. All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872394" httpUri="https://zenodo.org/record/13872394/files/figure.png" pageId="6" pageNumber="86">Figs. 3337</figureCitation>
). The ribs are ornamented with the same
<typeStatus id="8D7C8832FFB6FFA9A24F617EFCC0FE89" box="[804,852,339,365]" pageId="6" pageNumber="86">type</typeStatus>
of protrusions (
<figureCitation id="CAFC2A15FFB6FFA9A563617FFB04FE88" box="[1032,1168,338,364]" captionStart="FIGURES 3237" captionStartId="6.[136,243,1651,1673]" captionTargetBox="[177,1410,389,1626]" captionTargetId="figure-127@6.[177,1410,389,1626]" captionTargetPageId="6" captionText="FIGURES 3237. Oospores of Nitella singaporensis (isotype: LE): 32—general habit, 3337—surface ornamentation of fossa and ribs at different magnification. Scale: 32—40 μm, 33, 34—10 μm, 35—8 μm, 36—4 μm, 37—1 μm. All photos by R. Romanov." figureDoi="http://doi.org/10.5281/zenodo.13872394" httpUri="https://zenodo.org/record/13872394/files/figure.png" pageId="6" pageNumber="86">Figs. 33, 34</figureCitation>
).
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