Pseudostichopus Théel, 1886

Genus Pseudostichopus Théel, 1886 View in CoL

Diagnosis (amended from O’Loughlin and Ahearn, 2005, for Miller et al., 2017 erection of Pseudostichopodidae ). Characters of Molpadiodemidae (formerly pygal-furrowed Synallactidae ): prominent appendages (tube feet, papillae) along the paired radii only; longitudinal muscles cylindrical, not flat, narrowly attached to the body wall; gonad tubules not branched, arising in series along the gonoduct, not from a common base; ossicles sometimes present in tube feet and papillae; tentacle ossicles predominantly unbranched rods, rarely rods with ends intertwining, and side branches fused to create mesh.

Remarks. Cosmopolitan genus with 12 currently accepted species worldwide, four of those previously reported for Australia: Pseudostichopus hyalegerus , P. mollis , P. peripatus and P. spiculiferous . Four lots of Pseudostichopus were recorded for the IOT material, identified here to genus level. Pseudostichopus and Molpadiodemas can have a very similar body form. Where tube feet or papillae are obvious on the paired radii this indicates Pseudostichopus , but if these are inconspicuous the only other simple diagnostic feature to split thegeneraiscylindricallongitudinalmusclesin Pseudostichopus (fig. 35d) compared to flattened and broadly attached ones in Molpadiodemas (fig. 34a, b). As with Molpadiodemas , ossicles being absent from the body wall and variable in other places make them difficult to use diagnostically without further work. Both sequenced Pseudostichopus from the IOT are genetically within the well-supported Pseudostichopus clade (fig. S4).