Ophiocreas lissum (H.L. Clark, 1939 )

Ophiocreas lissum (H.L. Clark, 1939)

Fig. 3e View FIGURE 3

Asteroschema lissum Clark, H.L., 1939: 37 – 41 View in CoL , fig. 1 – 3.

Non Asteroschema cf lissum View in CoL . — Nethupul et al. 2022b: 198 – 201 View Cited Treatment , fig. 16 – 17.

STUDY MATERIAL. — JC066 : stn 8-3, Atlantis Bank, 32° 42.658´S, 57° 16.371´E to 32° 42.64´S, 57° 17.58´E, 707 m, 9/12/2011: 1 ( NHMUK 2025.27 About NHMUK ) ( DNA code= JC066-3605 ) GoogleMaps . — JC066: stn 8-22, Atlantis Bank, 32° 42.225´S, 57° 18.02´E to 32° 42.59´S, 57° 17.01´E, 1000 m, 13/12/2011: 1 ( NHMUK 2025.26 About NHMUK ) ( DNA code= JC066-3747 ) GoogleMaps .

COMPARATIVE MATERIAL EXAMINED. Ophiocreas lissum (H.L. Clark, 1939) : Chargos /18, Great Chargos Bank , Eagle Island, 6° 11.27326´S, 71° 19.10177´E, 488 m, 20/10/2022. Chargos/4, Peros Banhos, Ile de Pierre, 5° 18.633´S, 71° 43.447´E, 486 – 499 m, 16/10/2022 ( DNA code=Chargos.031). PAMELA-MOZ01/DW1, Glorieuses, 11° 22.756´S, 47° 16.4097´E to 11° 22.749´S, 47° 17.2302´E, 753 – 824 m, 28/9/2014 GoogleMaps , MNHN IE.2013.8420 ( DNA code=IE.2013.8420).

Distribution. Maldives and Chargos ( 486 – 797 m), Îles Glorieuses ( 753 – 824 m), Atlantis Seamount ( 707 – 1000 m).

Remarks. The two JC066 specimens measure 14 mm dd (NHMUK 2025.27) and 10 mm dd (NHMUK 2025.26) with arms at least 13x dd, and purple/brown/pink in colouration. The radial shields are covered in skin but can be seen as white radial markings that extend from the margin to centre of disc. There are tiny ossicles buried in the skin of the dorsal disc and arms, around 25 – 42 granules per square mm. The lateral arm plates do not extend across the dorsal midline of the first 9 or so segments, leaving a sunken groove of skin that lies on top of the gonads that extend along the arm. But these segments are not transversely expanded. There are 1 – 2 dental papillae at the tip of each jaw and sometimes a low domed lateral oral papilla to the side of the apex. The first 2 segments have no arm spines, the second 10 – 12 have one, and after that two. The inner arm spines become much longer and clavate by the 21 – 24th arm segment. Two Chargos specimens are similar except the larger one (Chargos 18) has 2 arm spines by segment two. The 17 mm dd specimen from Îles Glorieuses (IE.2013.8420) has 6 equal arms and arm spines that start on the 2nd segment. The epidermal granules are difficult to see.

We have identified these specimens as Asteroschema lissum on the basis of the small granules embedded in the thick skin covering the disc and arms, as well as the type location ( Maldives, 797 m). But there are some differences from the unique 7.5 mm holotype, which has 2 arm spines on segment 2, 3-5 ill-defined lateral oral papillae on the sides of the jaw, and radial shields that don’t extend to the centre of the disc. But this specimen is small and dry, and it is unclear if these differences are significant, given the morphological variation shown by our material .

Our phylogeny shows this species embedded within an Ophiocreas clade that includes O. sibogae Koehler, 1904 , O. carnosum Lyman, 1879 , and O. caudatus Lyman, 1879 . We temporarily transfer this species to Ophiocreas pending a Asteroschema-Ophiocreas revision. The type of Ophiocreas ( O. oedipus Lyman, 1879 ) is in a separate clade to O. lissum . Furthermore, our phylogeny shows that the type species of Asteroschema , A. oligactes (Pallas, 1788) , is a long-branched taxa that is sister to all other species and is likely to be monotypic (at least at the subgenus level). The traditional character that distinguished Asteroschema and Ophiocreas , disc granules present in the former and absent in the latter, does not hold. Several species of Ophiocreas can have some small granules in the skin (e.g., O. lissum , and O. corali ) and other species ( O. gilolense Döderlein, 1927 and O. spinulosum ( Lyman, 1883)) have small tubercles on the dorsal arm surface.

The specimens identified as A. cf. lissum by Nethupul et al. (2022b) cluster separately from our material on our phylogeny and likely represent a separate species. Three other species of Asteroschema recorded from the Indian Ocean, A. flosulum Alcock, 1893 , A. cf. arenosa (see Baker et al. 2018), and A. cf. igloo Baker, 1980 (see O’Hara 2024), differ in having prominent globular granules on their dorsal surface.