Paelopatides sp.

Paelopatides sp. MoV. 7337

Material examined. NMV F296843 About NMV * (1) and NMV F296844 About NMV * (1) [IN 2021 V04 012] ; NMV F308220 About NMV * (1) [IN 2022 V08 120] .

Diagnosis of IOT material. ( NMV F296844). Large, round, light purple specimen, up to 19.8 cm long and 15.5 cm wide, body very thick but depressed, with an extensive lateral brim visible from the ventral surface only (fig. 48 b). Skin thin but opaque. Mouth ventral, anus appears subdorsal to terminal. Complete cover of scattered dark-purple papillae dorsally and carrying over onto the visible ventral brim. Ventral interambulacra is bare, midventral line is deeply furrowed and wrinkled. Some scattered midventral tube feet observed, but mostly obscured by wrinkles and ridges so could not ascertain pattern. No ossicles found. Specimen after preservation shrinks to 18.5 cm long, 11.5 cm wide, and 2.5 cm high. Looks more like previous species Paelopatides sp. MoV. 7336 once preserved as much more reduced, flattened, and oval rather than round, but texture much softer and more gelatinous than Paelopatides sp. MoV. 7336 and thin top layer of skin also stripped. Preserved colour closer to light purple and black dorsally, ventral surface retains purple colour. All three specimens collected look superficially quite different, the two below placed here with reservations, based on genetic evidence. Brief descriptions of the two remaining specimens are as follows.

NMV F296843: Small, dark purple, gelatinous, dorsoventrally flattened specimen, ~ 8.5 cm long and 4.5 cm wide. Skin semitranslucent to opaque. Cylindrical gut visible. This specimen was damaged with no obvious appendages, but multiple dorsal canals visible through skin indicate potential scattered papillae.

NMV F308220: Cylindrical, elongated, purple/brown to cream specimen, severely damaged and stripped of skin and appendages, ~ 12.5 cm long x 2.8 cm wide x 2 cm high (fig. 48c). Mouth ventral. Anus terminal. No ossicles found. Potentially just the central cavity of a specimen with entire brim stripped, but no skin left to confirm this.

Remarks. Initially identified superficially as Benthothuria funebris due to the general colour and form of NMV F296844, but genetics places this firmly within Paelopatides , and both genetics and general morphology distinguish it from Paelopatides sp. MoV. 7366 above. The complete cover of dorsal papillae does not clearly fit the genus diagnosis for Paelopatides ( SolÍs-MarÍn, 2003), but excluding the presence of ossicles it suits the more general adaptation of SolÍs-MarÍn’s diagnosis by Wirawati and Setyastuti (2021): “ Paelopatides : body distinctly depressed with slightly larger brim surrounding the body; ventral tube feet arranged in the two rows from posterior up to the middle part of the body; and ossicle with simple triradiate rods”. Unable to ascertain pattern of ventral tube feet to use the key to southern hemisphere Paelopatides ( Martinez et al., 2019) . Round shape and complete dorsal cover of papillae along with absence of ossicles does not clearly fit any of the species described in Koehler and Vaney (1905). Lack of ossicles along with additional papillae and the anus not being clearly dorsal suggests the need for further comparison against Benthothuria species for this lineage. We note that morphologically Paelopatides can look very similar to Benthothuria , both including large purple species with thick, oval form, though Benthothuria has no ossicles and anus is terminal. SolÍs-MarÍn (2003) noted that phylogenetics showed Paelopatides and Benthothuria are related, this relationship was not examined by Miller et al. (2017), and Benthothuria is currently placed directly under Persiculida rather than with Paelopatides in Synallactidae . We identify our specimens here as Paelopatides sp. MoV. 7337, 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, Cocos (Keeling) Islands Territory, Rudist Seamount Stn., Christmas Island Territory, off McPherson Point, 2000–3839 m.

References. Koehler and Vaney (1905), Martinez et al. (2019), SolÍs-MarÍn (2003), Wirawati and Setyastuti (2021).