New sciaphilic plakinids (Porifera, Homoscleromorpha) from the Central-Western Pacific Author Lage, Anaíra Author Muricy, Guilherme Author Ruiz, César Author Pérez, Thierry text Zootaxa 2018 2018-08-31 4466 1 8 38 journal article 29187 10.11646/zootaxa.4466.1.4 0b1b168f-93cc-4ca7-8a40-bb6cbbe0ae24 1175-5326 1454345 AF8D251B-6412-4CBB-900E-D9E7506C9545 Plakinastrella osculifera sp. nov. ( FIgS. 7–8 , TAbLE 3 ) Definition. Plakinastrella ENcRUSTINg, bROWN, WITH OScULES cONSPIcUOUS, AbUNdANT ANd REgULARLy dISTRIbUTEd. TANgENTIAL SkELETON RETIcULATEd, WITH UNIfORM, SMALL cIRcULAR MESHES. EcTOSOMAL cAVITIES ROUNdEd, SUbEcTOSOMAL LAcUNAE LARgE ANd IRREgULAR, bASAL cAVITIES AbSENT. DIOdS, TRIOdS ANd cALTHROPS IN TWO SIZE cLASSES EAcH: dIOdS 14–150 ANd 210–277 µM LONg, AcTINES Of TRIOdS 20–62 ANd 87–147 µM, AcTINES Of cALTHROPS 2–40 ANd 57–135 µM. MIcRORHAbdS AbSENT. Type Material. HOLOTyPE : MNRJ 18459 ( 130205 -NC10-01) cOLLEcTEd Off HIENgHèNE, NEW CALEdONIA ( 20°36.756’S , 164°56.958’E ), IN A NETWORk Of TUNNELS cROSSINg AN ISLET , AT 22–23 M dEPTH. FEbRUARy 0 5, 2013, cOLL. THIERRy PÉREZ . PARATyPE: MNRJ 21831, SAME dATA Of HOLOTyPE. Description. THIN TO THIckLy ENcRUSTINg SPONgE, VERy LARgE (UP TO 45 cM LONg by 40 cM WIdE), WITH IRREgULAR OUTLINE. EXTERNAL cOLOUR bROWN WITH LIgHT bROWN PATcHES in vivo ( FIg. 7A ) ANd HOMOgENEOUSLy bROWN AfTER fIXATION; THE INTERIOR IS LIgHTER THAN THE SURfAcE. SURfAcE SMOOTH bUT UNEVEN. OScULES AbUNdANT, cONSPIcUOUS, 0.5–3.0 MM IN dIAMETER, cIRcULAR, SLIgHTLy ELEVATEd, REgULARLy dISTRIbUTEd ON THE SURfAcE. CONSISTENcy RELATIVELy fIRM. Anatomy. AqUIfEROUS SySTEM LEUcONOId. EcTOSOMAL cAVITIES SMALL, ROUNdEd, 30–108–310 µM, LOcATEd OVER LARgE, IRREgULAR SUbEcTOSOMAL LAcUNAE ( FIg. 7B–C ). BASAL cAVITIES AbSENT. IN TRANSVERSE SEcTIONS, THE SkELETON IS A dENSE, dISORgANIZEd RETIcULATION Of dIOdS, TRIOdS, ANd cALTHROPS, SLIgHTLy dENSER bETWEEN THE EcTOSOMAL cAVITIES ANd AT cANAL bORdERS ( FIgS. 7B–D ). THE bASE Of THE SPONgE IS LINEd by A PALISAdE ANd A TANgENTIAL LAyER Of SMALL SPIcULES, MAINLy dIOdS ( FIg. 7B ). LARgE dIOdS, TRIOdS ANd cALTHROPS ARE dISPERSEd THROUgHOUT THE cHOANOSOME ( FIg. 7D ). IN TANgENTIAL SEcTIONS, THE EcTOSOMAL SkELETON IS A SIMPLE ANd UNIfORM RETIcULATION Of MULTISPIcULAR SPIcULE TRAcTS fORMINg cIRcULAR MESHES 48–82–105 µM IN dIAMETER ( FIg. 7E ). Spicules ( TAbLE 3 ). DIOdS Of TWO SIZE cATEgORIES, SIMILAR IN SHAPE: STRAIgHT OR SLIgHTLy cURVEd, SMOOTH, AcERATE, WITH cENTRAL IRREgULARITy VARyINg fROM STRONgLy S-bENT TO SLIgHTLy THIckENEd, WITH LARgE SIZE VARIATION: FULL SIZE: DIOdS I ( FIg. 8A ) AbUNdANT, 14–79.1–150 / 1.7–5.0–10 µM. DIOdS II ( FIg. 8B ) VERy RARE TO AbSENT, 210–243–277 / 7–7.5–8 µM. FIGURE 7. Plakinastrella osculifera sp. nov. A, holotype MNRJ 18459 in vivo . B, Transverse section through the whole sponge body. C, transverse section of ectosome and upper choanosome with small rounded ectosomal cavities, large subectosomal lacunae, and disorganized choanosomal skeleton. D, disorganized choanosomal skeleton with large triods and calthrops dispersed. E, tangential section of the ectosomal reticulation with simple rounded meshes. Key: b, basal layer; ca, canals; ch, choanosomal skeleton; ec, ectosomal cavities; s, surface; sl, subectosomal lacunae. TRIOdS Of TWO SIZE cATEgORIES. TRIOdS I cOMMON, SLENdER, SMOOTH, IRREgULAR, Y- OR T-SHAPEd, AcERATE ( FIg. 8C ). AcTINES 20–35.6–62,5/ 2.5–5.9–10 µM. TRIOdS II RARE, STOUT, SMOOTH, REgULAR, Y- OR T- SHAPEd, AcERATE ( FIg. 8D ). AcTINES 87.5–114–147 / 12.5–17–22.5 µM. CALTHROPS ALSO Of TWO SIZE cATEgORIES. CALTHROPS I AbUNdANT, SLENdER, SMOOTH, REgULAR, WITH AcERATE ENdS ( FIg. 8E ). AcTINES 2.5–26.3–40 / 2.5–5.3–7.5 µM. CALTHROPS II cOMMON, STOUT, SMOOTH, REgULAR, WITH AcERATE ENdS ( FIg. 8F ). AcTINES 57.5–92–135 / 10–14.9–22.5 µM. Reproduction. REPROdUcTIVE ELEMENTS WERE NOT fOUNd. Ecology. Plakinastrella osculifera sp. nov. dWELLS IN A SEMI-dARk HAbITAT. THIS SPONgE WAS cOLLEcTEd AT 22–23 M dEPTH IN MUddy LITTLE LEdgES ON THE SIdE Of THE TUNNEL, SHAdEd fROM THE LIgHT by VERy TURbId WATER, LARgE SEA-fANS, ANd bLAck cORALS cOLONIZINg THE AccESS TO THE cAVE. THIS NEW SPEcIES IS SyNTOPIc Of THE REcENTLy dEScRIbEd P. kanaky (RUIZ et al. 2015). NO SIgNS Of EPIbIOSIS OR PREdATION WERE ObSERVEd ON ITS SURfAcE. Distribution. NEW CALEdONIA ( FIgS. 1 , 3 ). FIGURE 8. Plakinastrella osculifera sp. nov. Spicules (SEM). A, diods I. B, diods II. C, triods I. D, triods II. E, calthrops I. F, calthrops II. Etymology. THE SPEcIES NAME osculifera dERIVES fROM THE AbUNdANcE ANd REgULAR dISTRIbUTION Of THE cONSPIcUOUS OScULES Of THIS SPONgE. Taxonomic remarks. THE NEW SPEcIES IS dISTINgUISHEd fROM ITS cONgENERS MAINLy by SPIcULE SIZE. IT HAS TWO SIZE cATEgORIES Of dIOdS, TRIOdS, ANd cALTHROPS, WITH THE LARgEST dIOdS ATTAININg 277 µM ANd THE AcTINES Of TRIOdS ANd cALTHROPS UP TO 147 µM ANd 135 µM, RESPEcTIVELy. IN SEVEN SPEcIES Of Plakinastrella , ALL SPIcULES ARE SHORTER THAN APPROXIMATELy 150 µM: Plakinastrella clathrata LENdENfELd, 1900, P. clippertonensis , P. copiosa , P. globularis , P. microspiculifera , P. nicoleae sp. nov. , ANd P. mixta . IN OTHER SIX SPEcIES, THE dIOdS ARE APPROXIMATELy 200 µM OR MORE bUT THE AcTINES Of THE TRIOdS ANd/OR THE cALTHROPS ARE MUcH SHORTER THAN 150 µM: P. ceylonica ( DENdy, 1905 ), P. mammillaris LENdENfELd, 1907 , P. minor ( DENdy, 1916 ), P. onkodes ULIcZkA, 1929 , P. stinapa VAN SOEST et al. , 2014, ANd P. trunculifera TOPSENT, 1927 . Plakinastrella oxeata TOPSENT, 1904 ANd P. polysclera LÉVI & LÉVI, 1989 HAVE MUcH LARgER SPIcULES, WITH dIOdS OVER 1000 µM ANd AcTINES Of TRIOdS ANd cALTHROPS OVER 400 µM LONg. Plakinastrella osculifera sp. nov. IS WELL cHARAcTERIZEd WITHIN THE gENUS by THE cOMbINATION Of LARgE ENcRUSTINg SHAPE, AbUNdANT ANd cONSPIcUOUS OScULES, ANd by THE SIZE Of ITS SPIcULES.