CeDAMar Exchange Program for Taxonomists: a fellowship program for deep-sea taxonomists
Examination of holothurians of the families Psychropotidae and Elpidiidae
collected during the RRS Discovery Cruise 300 in the Crozet Plateau area.

Report

Antonina Rogacheva

P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences, Nakhimovsky Pr. 36, 117997, Moscow, Russia

Main goals

The main goal of my work in the United Kingdom was to examine material on deep-sea holothurians of the families Elpidiidae and Psychropotidae collected by the CROZEX expedition and stored at the National Oceanographic Centre, Southampton (NOCS). During the visit it was intended 1) to examine the CROZEX collection of elpidiid holothurians of the genus Kolga; to compare specimens of Kolga from off Crozet and NE Atlantic; 2) to examine the CROZEX collection of psychropotid holothurians; 3) to study the Challenger collection of type species of psychropotids stored at the National History Museum, London (NHM).

Results

During my visit to NOCS and NHM (20 August-21 September) I examined deep-sea holothurians of the following taxa:

1) Fam. Elpidiidae

Genus Kolga

Kolga nana Théel, 1882

Off Crozet

St. 15775#4 (1430 spec.) 

NE Atlantic

St. 50603#1 (1204 spec.)

St. 10114#1 (~4400 spec.)

St. 52403#21-23 (1050 spec.)

St. 10113#1 (85 spec.)

St. 9754#3 (1 spec.)

St. 9756#11 (23 spec.)

Specimens of Kolga sp. from both sites were found to belong to the species Kolga nana Théel, 1882. This species was synonymized by Hansen (1975) and therefore is currently invalid. Examination of the Crozet and NE Atlantic material on Kolga as well as the type series of Kolga nana provided a basis for re-erection and re-description of this species.

Kolga nana, St. 15775#4, spicules of tube feet. Two types of spicules with dominant small irregular C-shaped elements differ this Antarctic-North Atlantic species from the Arctic species Kolga hyalina.

2) Fam. Psychropotidae

Genus Benthodytes

Benthodytes sp.nov.

Off Crozet

St. 15773#17 (5 ind.)

This species is probably new to science.

Benthodytes sanguinolenta (Théel) Théel, 1882

Off Crozet

St. 15773#23 (96 spec.)

St. 15773#17 (53 spec.)

St. 15773#32 (67 spec.) 

This is the well known cosmopolitan species. In this species I studied the variability of characters of external morphology.

Benthodytes sanguinolenta from St. 15773#23

Benthodytes sp. A

Off Crozet

St. 15773#23 (2 spec.)

St. 15773#17 (12 spec.)

St. 15773#8 (54 spec.)

St. 15775#4 (45 spec.)

St. 15773#32 (32 spec.)

Examination of the type material of two Challenger species Benthodytes sordida Théel, 1882 and Benthodytes abyssicola Théel, 1882 at NHM revealed that:

1) they are probably synonyms (Benthodytes sordida is the younger synonym of Benthodytes abyssicola)

2) Benthodytes sp. A should be probably regarded as Benthodytes abyssicola

Genus Psychropotes

Psychropotes longicauda Théel, 1882

Off Crozet

            St. 15773#8 (2 spec.)

St. 15773#23 (16 spec.)

St. 15775#4 (1 juv.)

Challenger type collection

Cat.Nr. 83.6.18.58 (1 ind.); 83.6.18.59 (1 ind.); 83.6.18.57 (1 ind.); 83.6.18.61 Psychropotes longicauda var. fusco-purpurea (1 ind.); 83.6.18.60 Psychropotes longicauda var. monstrosa (1 ind.)

NE Atlantic

St. 50603#1 (20 ind.)

The species Psychropotes longicauda Théel, 1882 is regarded  as a cosmopolitan species despite its high variability. I found some differences both in external and spicule morphology between specimens from Crozet collection and specimens from Porcupine Abyssal Plain in the NE Atlantic. However more material on this species from different localities needs to be studied to be absolutely sure that there are no intermediate stages between these differences.

The Crozet specimens of Psychropotes longicauda are similar to the type material.

Psychropotes scotia (Vaney, 1908)

Off Crozet

            St. 15773#23

            St. 15773#8

This species so far was known only from a single record in the Antarctic. This material will be used for further re-description of Psychropotes scotia.

Genus Psycheotrephes

 Psycheotrephes n.sp.

Off Crozet

            St. 15773#23 (4 incomplete specimens)

This species is probably new to science.

Psycheotrephes recta (Vaney, 1908)

Off Crozet .

St. 15775#4 (3 spec.)

This species so far was known only from a single record in the Antarctic. These specimens were tentatively identified as Psychropotes recta, based on arrangement of papillae. However a comparison with the type material is required.

Conclusions

Seven species of psychropotid holothurians belonging to all three known genera in the family were found in the CROZET collection. Two of the species are probably new to science. Psychropotes scotia (Vaney, 1908) and Psycheotrephes recta (Vaney, 1908) were known only from single records and the CROZEX material will be used for re-description of at least the first species. Benthodytes sp.A from the Crozet plateau, based on the comparison with the type material of Benthodytes sordida and Benthodytes abyssicola, belongs to one of these species. Also it was found that Benthodytes abyssicola should be probably sinomyzed with Benthodytes sordida. Both species were regarded by Bent Hansen (1975) as of unclear taxonomical position. The CROZEX collection will help to clarify the status and diagnosis of these species.

Currently I am working together with Ian Cross (NOCS) on a paper on psychropotids from the Crozet plateau and we plan to finish the manuscript by the end of this year.

            Specimens of Kolga in the Crozet material were identified as Kolga nana (Théel) Théel, 1882. This species was synomyzed with the type species of the genus, Kolga hyalina Danielssen and Koren, 1879 from the Arctic Ocean. Re-examination of the type material of Kolga nana stored at NHM showed that it is separate species. Material on Kolga nana from the CROZEX collection will be used in re-description of this species and revision of the genus Kolga.