Corresponding author: Sabyasachi Sautya (
Academic editor: R. Pronzato
New hexactinellid sponges were collected from 2589 m depth on the Carlsberg Ridge in the Indian Ocean during deep-sea dredging. All fragments belong to a new genus and species,
The family
Global distribution of
Fan (or funnel)-like basiphytous sponge with thin walls and numerous epirhyses. Framework contains several layers of regular dictyonal strands (mainly from the atrial side) and irregular fused hexactinic spicules (which form a typical aulocalycoid skeleton) located among them and from the dermal side. Dermalia and atrialia are pentactins. Microscleres are discohexasters.
The name of the genus is derived from its place of collection and refers to the Indian Ocean.
It is likely that the body is rather fan-like than cup or funnel-like since the fragments are flat, thus the funnel-like body shape should be of a very large diameter. The original shape of the body is already known in
The walls in the new genus are relatively thick (in comparison with other representatives of the family). Usually the aulocalycoid skeleton is composed of large hexactins located approximately in a single layer, their rays are distributed in a single plane (the distal one and proximal are bent), fusion takes place at points of mutual contact, so the wall thickness includes an only dictyonal layer. The regular dictional strands are observed in
The presence of epirhyses type of channelization is unique for the family. It is known in
The loose spicules are typical for the family where few species possess scepters and uncinates. A more simplified spicule set is observed in
The situation with aulocalycoid, paraulocalycoid and skeleton of
The species name is derived from its type locality, the ridge (Carlsberg Ridge) habitat.
Carlsberg Ridge, Indian Ocean: ‘Akademic Bois Petrov’ station. DR-13,
NIO/BOD/5-H/2011, stored in ethanol. NIO/SPONGE/DR-13/H, slide, stored in ethanol. IORAS (Institute of Oceanology of Russian Academy of Sciences) 5/2/ NIO/BOD/5-H/2011 (slides).
Spicules framework is seems to be constructed of different elements: regular, longitudinally directed dictyonal strands, located mostly in the vicinity of the atrial surface (approximately 4 layers) and irregular hexactins fused to each other and to the regular elements at points of mutual contacts, at all levels of the wall thickness. All framework surfaces are covered by very small spines, the free outer ray ends are conically pointed. The dictyonal strands are easily observed, they have diameter 0.09–0.12 mm, beams between the strands are 0.03–0.07 mm in diameter. Free rays of the dictyonal strands are protruded atrially. The meshes between the dictyonal strands and their connecting beams are rather regular, usually rectangular, 0.3–0.5×0.5–0.8 mm. Adjacent hexactinic spicules located among the dictyonal strands are irregularly and sparsely distributed among their meshes, they are connected to the framework by a single ray (small hexactins with rays 0.07–0.12/0.003–0.006 mm) and often at points of mutual contact (large hexactins with rays about 0.5/0.012–0.018 mm). The meshes there are very irregular and of different sizes. The dictyonal strands may be also observed in the vicinity of dermal surface but due to numerous epirhyzes, they are not straight as those from the atrial surface.
Microscleres are stellate discohexasters only, with 8–14 secondary rays. The diameter of the discohexaster is 0.025–0.046 mm, their primary rosette is 0.006–0.018 mm in diameter (
Scaning Electron Microscopy of
Spicule dimensions of
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N | 25.000 | 25.000 | 25.000 | 25.000 | 28.000 | 28.000 |
Min |
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0.060 |
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0.042 |
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Max |
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0.360 |
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Avg | 0.280 | 0.103 | 0.228 | 0.100 | 0.039 | 0.012 | |
SD | 0.099 | 0.048 | 0.081 | 0.067 | 0.005 | 0.003 | |
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N | 16.000 | 16.000 | 12.000 | 12.000 | 14.000 | 14.000 |
Min | 0.168 |
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0.108 | 0.060 | 0.032 | 0.009 | |
Max | 0.408 | 0.180 | 0.360 | 0.156 | 0.042 | 0.018 | |
Avg | 0.256 | 0.113 | 0.264 | 0.115 | 0.037 | 0.012 | |
SD | 0.070 | 0.049 | 0.076 | 0.032 | 0.003 | 0.002 | |
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N | 7.000 | 7.000 | 6.000 | 6.000 | 3.000 | 3.000 |
Min | 0.240 | 0.078 | 0.132 | 0.048 | 0.039 | 0.012 | |
Max | 0.414 | 0.192 |
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0.114 | 0.041 | 0.014 | |
Avg | 0.348 | 0.127 | 0.241 | 0.075 | 0.040 | 0.013 | |
SD | 0.060 | 0.039 | 0.095 | 0.023 | 0.001 | 0.001 | |
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N | 5.000 | 5.000 | 4.000 | 4.000 | 1.000 | 1.000 |
Min | 0.168 | 0.072 | 0.150 |
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0.032 | 0.008 | |
Max | 0.312 | 0.168 | 0.240 | 0.084 | 0.032 | 0.008 | |
Avg | 0.252 | 0.110 | 0.197 | 0.066 | 0.032 | 0.008 | |
SD | 0.067 | 0.037 | 0.038 | 0.021 | - | - |
Since all these fragments of the holotype and of paratypes were collected from the same station, there is a great probability that they belong to a single specimen.
1 | Dictyonal strands not obvious, likely entirely absent (if present they are distributed chaotically), choanosomal hexactins fuse at points of mutual contacts, their distal and proximal rays are bent in the tangential plane (aulocalycoid skeleton) | 2 |
– | Dictyonal strands present in addition to aulocalycoid skeleton, dictyonal strands are distributed in common, longitudinal direction | 5 |
2 | Body of branching tubes or cup with short lateral tubes | 3 |
– | Body fan- or tongue-shape without tubular elements |
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3 | With rhopalasters as distinctive microscleres |
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– | Without rhopalasters | 4 |
4 | Parietal gaps large and closely spaced; wall lace-like |
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– | Parietal gaps small, sparse; wall thin and mostly imperforate |
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5 | Walls unchannelized |
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– | Walls channelized by epirhyses |
The authors wish to express their gratitude to the Council of Scientific and Industrial Research (CSIR) for financial support to the Net-Work project ‘Indian Ridge studies’. We also thank the Director of NIO (Goa) for the facilities. We wish to acknowledge the team Leader Dr. Kamesh Raju and entire ‘Ridge Group’ for excellent team work during the deep-sea cruises. We also thank the Captain of the cruise ‘Akademic Boris Petrov’ and his group for help in collecting the priceless sample from the deep-sea. Our special thanks to Durbar Ray for collecting the samples and to Mr. VD Khedekar for help during Scanning Electron Microscopy at NIO, Goa, India. The senior author thanked CSIR for awarding the Senior Research Fellow which gave the opportunity to carry out this work. We gratefully acknowledge CenSeam (A Global Census of Marine Life on Seamounts - a CoML project) for travel support under the”CenSeam minigrant programme 2010” to analyze the sponge and associated fauna at P.P. Shirshov Institute of Oceanology of Russian Academy of Sciences, Moscow. Comments and suggestions from two anonymous reviewers helped in improving the manuscript. This is contribution No. 5040 of NIO (CSIR) Goa.