Echinoderes galadrielae Grzelak & amp; Sørensen 2022, sp. nov.
Author
Grzelak, Katarzyna
Author
Sørensen, Martin V.
text
Zoological studies
2022
Zool. Stud.
55
32
32
32
http://dx.doi.org/10.5281/zenodo.7225407
journal article
10.5281/zenodo.7225407
Echinoderes serratulus
sp. nov.
Yamasaki
urn:lsid:zoobank.org:act:
68D196A3-A3D0-48AD-92FC-9406562D8CD0
[New Japanese name: Nokogiri togekawa]
Material examined
: All specimens collected
25 November 2014
at
10 m
depth near Hon Mieu Island, Nha Trang,
Vietnam
(
12°11.60'N
,
109°13.96'E
).
Holotype
: adult female (ZIHU-5053), mounted in Fluoromount G
®
.
Allotype
: adult male (ZIHU-5054), mounted in Fluoromount G
®
.
Paratypes
:
one adult
female and
two adult
males (ZIHU-5055-5057), mounted in Fluoromount G
®
. Additional material:
four specimens
for
SEM
(
three adult
females and
one adult
male), mounted on aluminum stubs.
Etymology
: The species name
serratulus
is from Latin, meaning ‘serration’, referring to the species’ conspicuous primary pectinate fringe.
Diagnosis
:
Echinoderes
with short acicular spine middorsally on segment 4 and sublaterally on segments 6 and 7; lateroventral tubules on segments 5 and 8, midlateral tubules on segment 9, and laterodorsal tubules on segment 10; large sieve plates on segment 9; primary pectinate fringes ventrally on segments 1-9 conspicuous, with longer fringe tips; tips of ventromedial primary pectinate fringes on segments 2-5 obliquely orientated, pointing towards midventral line; lateral terminal spines short and plump, length 12-15% of trunk length.
Description
: Adult with head, neck and eleven trunk segments (
Figs. 8A, B
,
9A
,
10A
). See table 3 for measurements, and table 4 for positions of cuticular structures (sensory spots, glandular cell outlets, acicular spines, tubules and sieve plates).
Head consists of retractable mouth cone and introvert (
Figs. 10
A-C). Mouth cone with inner oral styles and nine outer oral styles. Exact number and arrangement of inner oral styles not observed. Each outer oral style composed of rectangular basal part and triangular distal part (
Fig. 10B
). Basal parts of outer oral styles alternate in size: five large anterior to odd sectors of introvert, and four slightly smaller ones in even sectors (
Figs. 10B
,
11
). Introvert composed of seven rings of spinoscalids and one ring of trichoscalids (
Figs. 10C
,
11
). Ring 01 includes ten primary spinoscalids, each with basal sheath and smooth long end-piece (
Fig. 10C
). Each basal sheath with three overlapping fringes. Proximal fringe extends into three flat projections, like a trident, covering next fringe. Middle fringe with two lateral projections overlapping end-piece. Distal fringe with five threads projecting between two projections of middle fringe. End-piece of primary spinoscalids is longest unit. Rings 02 and 04 with 10 spinoscalids; rings 03 and 05 with 20 spinoscalids. Spinoscalids in rings 02-05 similar in length. Rings 06 and 07 not examined with detail, but ring 06 with at least seven, and ring 07 with at least ten relatively short spinoscalids (
Fig. 11
). Six trichoscalids attached with trichoscalid plate in sectors 2, 4, 5, 7, 8, and 10.
Neck with 16 placids (
Figs. 8A, B
,
9A
,
11
). Midventral placid broadest (ca. 17 μm wide at base, ca. 12 μm wide at tip); remaining placids with similar size (ca. 10 μm wide at base, ca. 4 μm wide at tip).
Segment 1 consists of complete cuticular ring (
Figs. 8A, B
,
9A
). Non-bracteate cuticular hairs densely cover entire segment. Paired, rounded subdorsal and laterodorsal sensory spots located close to anterior margin of segment (
Figs. 8A
,
9C
). Rounded ventromedial sensory spots centered between anterior and posterior margins (
Figs. 8B
,
10D
). Type-1 glandular cell outlets situated anteriorly in middorsal and lateroventral positions (
Figs. 8A, B
,
9A, C
). Primary pectinate fringe conspicuous, with longer fringe tips, especially on ventral side (
Figs. 8A, B
,
9
A-C).
Segment 2 also with complete cuticular ring (
Figs. 8A, B
), with thick pachycyclus at anterior margin (
Figs. 8A, B
,
9
A-C). Entire cuticular surface, except anterior area, covered with bracteate cuticular hairs on this and following eight segments. Oval sensory spots in middorsal, laterodorsal, midlateral, and ventromedial positions (
Figs. 8A, B
,
9
A-C, 10D). Unpaired type- 1 glandular cell outlet present in middorsal position (
Fig. 8A
). Paired type-1 glandular cell outlets close to anterior margin in ventromedial position on this and following eight segments (
Figs. 8B, D
,
9A, B
). Type-2 glandular cell outlets in subdorsal, laterodorsal, and ventrolateral positions (
Figs. 8A, B
,
9
A-C). Type-2 glandular cell outlets show single large pore in LM and
SEM
(
Figs. 9B, C
; see also figures 12A, B for type-2 glandular cell outlet on segments 6 and 8). Posterior margin of segment with primary pectinate fringe having long tips, with ventromedial tips obliquely orientated, pointing towards the midventral line (
Figs. 8A, B
,
9
A-C).
Segment 3 and following eight segments consist of one tergal and two sternal plates (
Figs. 8A, B
,
9A
). Each plate with thicker pachycycli in anterior area (
Figs. 8A, B
,
9A, B
). Sensory spots in subdorsal, midlateral, and sublateral positions (
Figs. 8A
,
9A
). Two unpaired type-1 glandular cell outlets present middorsally (
Fig. 8A
). Primary pectinate fringes on this and following two segments as on segment 2. Secondary pectinate fringes, consisting of single belt of minute teeth, visible on anterior dorsal plate in
SEM
observation, at least on this and following five segments (
Fig. 10G
).
Segment 4 with short middorsal acicular spine (
Figs. 8A
,
10G
). Paired laterodorsal sensory spots and paired subdorsal type-2 glandular cell outlets present (
Figs. 8A
,
10G
). Paired type-1 glandular cell outlets present paradorsally on this and following six segments. Fringe tips on dorsal, lateral, and ventral sides similar in length and width.
Segment 5 with lateroventral tubules (
Figs. 8B
,
9D
,
10D, F
,
12A
). Paired sensory spots in subdorsal, midlateral, and ventromedial positions (
Figs. 8A, B
,
9A
,
10
D-F). Pair of type-2 glandular cell outlets in midlateral position (
Figs. 8A, B
).
Segment 6 similar to segment 5 except for absence of lateroventral tubules and presence of short sublateral acicular spines (
Figs. 8A, B
,
9A, D
,
10D, F
,
12A, C
). Primary pectinate fringes of this and following three segments with long, conspicuous fringe tips.
Table 3.
Measurements for adult
Echinoderes serratulus
sp. nov.
(in micrometers). Columns N and SD are sample size and standard deviation, respectively
| Character |
N |
Range |
Mean |
SD |
| TL |
5 |
321-359 |
348 |
15.32 |
| MSW-6 |
5 |
62-69 |
66 |
3.09 |
| MSW-6/TL |
5 |
17.9-19.9% |
18.9% |
1.00% |
| SW-10 |
5 |
54-59 |
56 |
1.76 |
| SW-10/TL |
5 |
15.1-17.0% |
16.1% |
0.81% |
| S1 |
5 |
36-39 |
37 |
1.25 |
| S2 |
5 |
33-37 |
35 |
1.82 |
| S3 |
5 |
28-31 |
30 |
1.21 |
| S4 |
5 |
31-34 |
33 |
1.28 |
| S5 |
5 |
34-38 |
37 |
1.68 |
| S6 |
5 |
38-42 |
40 |
1.51 |
| S7 |
5 |
40-48 |
45 |
2.86 |
| S8 |
5 |
46-53 |
50 |
2.67 |
| S9 |
5 |
47-53 |
50 |
2.37 |
| S10 |
5 |
44-46 |
45 |
0.66 |
| S11 |
5 |
44-48 |
46 |
1.75 |
| MD4 (ac) |
5 |
10-14 |
12 |
1.68 |
| LV5 (tu) |
5 |
11-13 |
12 |
1.14 |
| SL6 (ac) |
5 |
9-12 |
10 |
1.53 |
| SL7 (ac) |
5 |
9-13 |
11 |
1.71 |
| LV8 (tu) |
5 |
9-13 |
12 |
1.59 |
| ML9 (tu) |
5 |
16-21 |
19 |
1.96 |
| LD10 (tu) (m) |
3 |
39-41 |
40 |
1.11 |
| LD10 (tu) (f) |
2 |
16-17 |
17 |
0.96 |
| LTS |
5 |
44-49 |
46 |
1.65 |
| LTAS |
2 |
20-21 |
20 |
0.66 |
| LTS/TL |
5 |
12.4-14.7% |
13.4% |
0.86% |
| LTAS/TL |
2 |
5.6-5.8% |
5.7% |
0.11% |
Abbreviations: (ac), acicular spine; (f), female; LD, length of laterodorsal tubule; LTAS, length of lateral terminal accessory spine; LTS, length of lateral terminal spine; LV, length of lateroventral tubule; (m), male; MD: length of middorsal acicular spine; ML, length of midlateral tubule; MSW, maximum sternal width; S, segment length; SL, length of sublateral acicular spine; SW, standard width; TL, trunk length; (tu), tubule.
Table 4.
Summary of location of cuticular structures, tubules, and spines in
Echinoderes serratulus
sp. nov.
Position
| MD segment |
PD |
SD |
LD |
ML |
SL |
LV |
VL |
VM |
| 1 |
gco1 |
ss |
ss |
gco1 |
ss |
| 2 |
ss, gco1 |
gco2 |
ss, gco2 |
ss |
gco2 |
ss, gco1 |
| 3 |
gco1, gco1 |
ss |
ss |
ss |
gco1 |
| 4 |
ac |
gco1 |
gco2 |
ss |
gco1 |
| 5 |
gco1 |
ss |
ss, gco2 |
tu |
ss, gco1 |
| 6 |
gco1 |
ss |
ss, gco2 |
ac |
ss, gco1 |
| 7 |
gco1 |
ss |
ss, gco2 |
ac |
ss, gco1 |
| 8 |
gco1 |
ss |
ss |
gco2 |
tu |
gco1 |
| 9 |
gco1 |
ss |
ss |
tu |
si |
ss |
gco1 |
| 10 |
gco1 |
ss |
tu |
ss |
gco1 |
| 11 |
ss |
ltas (f), ps (m) |
lts |
Abbreviations: ac, acicular spine; (f), female condition of sexually dimorphic character; gco1, type-1 glandular cell outlet; gco2, type- 2 glandular cell outlet; LD, laterodorsal; ltas, lateral terminal accessory spine; lts, lateral terminal spine; LV, lateroventral; (m), male condition of sexually dimorphic character; MD, middorsal; ML, midlateral; PD, paradorsal; ps, penile spine; SD, subdorsal; si, sieve plate; SL, sublateral; ss, sensory spot; tu, tubule; VL, ventrolateral; VM, ventromedial.
Segment 7 similar to segment 6.
Segment 8 with lateroventral tubules (
Figs. 8B
,
9A, E
,
12B
). Paired sensory spots in subdorsal and laterodorsal positions (
Fig. 7A
). Paired type- 2 glandular cell outlets in midlateral position (
Figs. 8A, B
,
12B
).
Segment 9 with midlateral tubules (
Figs. 8A, C, D
,
9F
,
12B, D
). Paired subdorsal, laterodorsal, and ventrolateral sensory spots present (
Figs. 8
A- D, 9A, E). Sieve plates with oval sieve area and single posterior pore in sublateral position (
Figs. 8
B-D, 9E, 12B, D).
Fig. 8.
Echinoderes serratulus
sp. nov.
, camera lucida drawings. A, B, Holotype, female (ZIHU-5053), entire animal, dorsal and ventral views, respectively; C, D, allotype, male (ZIHU-5054), segments 9-11, dorsal and ventral views, respectively. Double, gray, and black circles indicate sensory spots, type-1 glandular cell outlets, and type-2 glandular cell outlets, respectively. Abbreviations: gco1, type-1 glandular cell outlet; gco2, type-2 glandular cell outlet; ldt, laterodorsal tubule; ltas, lateral terminal accessory spine; lts, lateral terminal spine; lvt, lateroventral tubule; mds, middorsal acicular spine; mlt, midlateral tubule; ps, penile spine; si, sieve plate; sls, sublateral acicular spine; ss, sensory spot.
Fig. 9.
Echinoderes serratulus
sp. nov.
, Nomarski photomicrographs of holotype female (ZIHU-5053). A, entire animal, ventral view; B, segments 2 and 3, ventral view; C, segments 1 and 2, dorsal view; D, segments 5 and 6, lateroventral view; E, segments 8 and 9, lateroventral view; F, segments 9-11, laterodorsal view; G, segments 10 and 11, ventrolateral view. Dashed circles indicate sensory spots. Abbreviations: gco1, type-1 glandular cell outlet; gco2, type-2 glandular cell outlet; ldt, laterodorsal tubule; ltas, lateral terminal accessory spine; lts, lateral terminal spine; lvt, lateroventral tubule; mlt, midlateral tubule; mvp, midventral placid; ppf, primary pectinate fringe; si, sieve plate; sls, sublateral acicular spine; sp, sternal plate.
Segment 10 with long laterodorsal tubules in males, short laterodorsal tubules in females (
Figs. 8A, C
,
9F
,
12E, G
;
Table 1
). Paired subdorsal and ventrolateral sensory spots present (
Figs. 8
A-D, 12E, G). Primary pectinate fringe with shorter and thinner tips than preceding segments in middorsal to ventrolateral areas, and with tips similar in length to those of preceding segments in ventromedial area.
Fig. 10.
Echinoderes serratulus
sp. nov.
, scanning electron micrographs. A, entire animal, lateroventral view; B, mouth cone, lateroventral view; C, introvert, ventrolateral view; D, segments 1-7, ventral view; E, segment 5, ventromedial view; F, segments 3-6, ventrolateral view; G, segments 3-5, dorsal view. Dashed circles indicate sensory spots. Abbreviations: gco2, type-2 glandular cell outlet; ha, hair; int, introvert; lts, lateral terminal spine; lvt, lateroventral tubule; mds, middorsal acicular spine; oos, outer oral style; ppf, primary pectinate fringe; psc, primary spinoscalid; sec, sector; seg, segment; spf, secondary pectinate fringe.
Segment 11 with short, plump lateral terminal spines (
Figs. 8
A-D, 9A, F, G, 10A, 12E-G). Pair of short lateral terminal accessory spines present in females (
Figs. 8B
,
9G
,
12E, G
), and three pairs of penile spines present in males (
Figs. 8D
,
12F
). Cuticular hairs absent. Paired sensory spots in subdorsal position (
Figs. 8A, C
,
12E
). Tergal plate partially divided at middorsal line from central to posterior part. Posterior edge of tergal plate projects laterally and ends in pointed tergal extensions (
Figs. 8
A-D, 12E).
Remarks
: The combination of the arrangement of spines and tubules and the presence of large sieve plates assigns
Echinoderes serratulus
sp. nov
to be a member of the
Echinoderes
coulli-
group (see also DISCUSSION). Within the group,
Echinoderes serratulus
sp. nov.
is similar to
E
.
annae
and
Echinoderes hwiizaa
Yamasaki and Fujimoto (2014)
in having paired tubules on segment 9, and plump lateral terminal spines on segment 11 (
Yamasaki and Fujimoto 2014
;
SØrensen et al. 2016
). It is also similar to
Echinoderes aspinosus
SØrensen et al. (2012)
in having paired large sieve plates on segment 9, and the tips of the ventral primary pectinate fringes pointing towards the midventral line on segments 2-5 (
SØrensen et al. 2012
).
Echinoderes serratulus
sp. nov.
differs from
E. annae
in having minute sublateral acicular spines on segments 6 and 7 (
SØrensen et al. 2016
).
Echinoderes serratulus
sp. nov.
differs from
E. hwiizaa
in having a middorsal acicular spine on segment 4 and a conspicuous ventral primary pectinate fringe on segments 1 and 2, and in lacking midlateral tubules on segment 8 (
Yamasaki and Fujimoto 2014
).
Echinoderes serratulus
sp. nov.
easily differs from
E. aspinosus
in having acicular spines and tubules on segments 4-10 (
E
.
aspinosus
lacks any acicular spines and tubules on segments 4-10) (
SØrensen et al. 2012
).