Benthodytes sp.

Benthodytes sp. MoV. 7338

Material examined. NMV F308238 About NMV * (1) [IN 2022 V08 131] , NMV F308278 About NMV * (1) [INV 2022 V08 149] NMV F308288 About NMV * (10) [IN 2022 V08 151] .

Diagnosis of IOT material. ( NMV F308238). Large light violet specimen with darker purple to maroon-red remnant patches. Elongated, semicylindrical body, dorsally convex, ventrally flattened, rounded anteriorly, and rounded to slightly tapered posteriorly, 20.5 cm long, 6 cm wide, 2 cm high (preserved). Body solid. Skin thin but firm and wrinkled, appearing to bubble near base of dorsal papillae (and through papillae). Ventral surface with light covering of sponge spicules, corals, bryozoans, and grit. Anus dorsal and subterminal. Mouth ventral with brown/maroon tentacles (retracted, ~7 visible) and circumoral papillae. Single rows of well-spaced papillae along dorsal radii. Eight dorsal papillae (4 pairs), with rounded bases and tapered or whip-like ends, some with bubbles or bulges, some very long, up to 85 mm (preserved). Lateral brim up to 1 cm wide, mostly solid with minimal exposed filamentous tips and no free tube feet. Midventral tube feet small, red/maroon, in irregular (paired to alternating) double row, bare at anterior and posterior ends. Multiple tissue samples only with rare cross and rod ossicles. Ventral body wall, single rod (160 μm), dorsal and ventral body wall with a few broken crosses with and without evidence of central apophyses (arms 160 μm), papillae with slightly larger crosses (arms ~240 μm). All three specimen lots collected look superficially quite different, the two below placed here with reservations, based on genetic evidence. Brief descriptions of the two remaining specimen lots follow.

NMV F308278: Very small pink specimen, 2 cm long, 0.5 cm wide (pre-preservation), with evidence of dorsal and potentially lateral papillae and a ventral tentacle crown. Little structure once preserved. Multiple tissue samples had either no ossicles or very rare (2 broken pieces) of Scotothuria -like hooked crosses. No S. herringi reported from this station (149) but presumed contaminants.

NMV F308288: Elongated, stripped, dorsoventrally flattened samples up to ~ 17 cm long and 2.5 cm wide (pre-preservation). Gelatinous and dark maroon/red to purple, bright pink when preserved. Lack of any distinct oral/anal end; tentacle crown or appendages indicate that these may be just gut and internal parts of specimens with no complete sample. Multiple tissue samples had either no ossicles or rare (2) Laetmogone -like wheels, considered likely contaminants. Note that the only other Benthodytes from this station (151) was too damaged to identify past genus level.

Remarks. External morphology of NMV F308238 is like IOT Benthodytes cf incerta , only with slightly wider, thicker brim, larger papillae and more red than purple colouring dorsally. Ossicles too scarce to demonstrate difference. We identify our specimens here as Benthodytes sp. MoV. 7388, noting the difference in external morphology between specimens and that additional morphological and genetic samples and more thorough literature review are required before confirming whether this is a new or existing species.

Distribution. These specimen lots only: Indian Ocean, Australian IOT, Christmas Island and Cocos (Keeling) Islands Territories, Cocos (Keeling) Stn., Noel Seamount Stn. and Raitt Ridge North Stn., 1589–3144 m.