Tromikosoma Mortensen, 1903

Anderson, Owen F., 2016, A review of New Zealand and southeast Australian echinothurioids (Echinodermata: Echinothurioida) — excluding the subfamily Echinothuriinae — with a description of a new species of Tromikosoma, Zootaxa 4092 (4), pp. 451-488 : 463

Tromikosoma Mortensen, 1903

Type species: Sperosoma koehleri Mortensen, 1903 , by original designation.

Diagnosis. Sperosomatinae with pores on oral surface arranged in more or less single series. Test plates extremely brittle. Buccal sacs, if present, rudimentary only (emended from Fell 1966).

Remarks. There are 6 assigned species, all Recent ( Table 4 ). The fragility of the Tromikosoma test invariably leads to breaking up of the test plates into small fragments, (possibly before as well as after capture, Mortensen 1935) making delineation of plate boundaries extremely difficult.