Rhynobrissus species

Family: Brissidae

Order: Spatangoida

Locality: North-East off Taiwan, 120-150 m, 2007

Dimensions: 24 x 19 x 13 mm


The highest point of the test is posterior the apical system. The upper side is convex, the petals slightly sunken, the test wegde-shaped seen from the posterior end. These features fit well with Rhynobrissus pyramidalis, which occurs really between China and Thailand and Singapur. But this species is regarded as shallow water (0-18 m) species. Another questions concerns the anal and subanal fascioles. Following Th. Mortensen all Rhinobrissus (he uses "i" and not "y") have very conspicuous anal fascioles, almost wholly enclosing the periproctal region, in the adult, well separated from the subanal fasciole. H. Schultz points out, that the subanal fasciole is in contact with the anal fasciole [not so in R. hemiasteroides (Hawaii, Tahiti and Australia) and R. tumulus (West coast of Australia)]. What is your opinion?