The Echinoid Directory

Trigonocidaris Agassiz, 1869, p. 263

[=Lamprechinus Doderlein, 1905, p. 622, type species Lamprechinus nitidus Doderlein, 1905; =Orechinus Doderlein, 1905, p. 622, type species Trigonocidaris monolini Agassiz, 1879.

See also subgenus Trigonocidaris (Tuberculocidaris)]

Diagnostic Features	Test small; profile low domal. Apical disc relatively large; dicyclic. Plates relastively smooth and naked; only a single perianal tubercle on inner edge of genital plates. Periproct subangular; a large suranal plate plus a small number of other periproctal plates. Ambulacral plating trigeminate, compouind in echinid style. Pore-pairs arranged uniserially, becoming very slightly crowded close to the peristome. One primary tubercle to each compound plate close to the pore zone, plus two ro three smaller perradial tubercles present. Interambulacral plates with central primary tubercle and a few smaller projecting secondary tubercles on either side; sutural pits small, but well developed, the secondaries projecting strongly from test surface giving a sculpted appearance. Primary tubercles imperforate and weakly crenulate. Peristomial moderately large with feeble buccal notches. Lantern camarodont. Spines short, simple, without cortex.
Distribution	Recent; Indo-West Pacific.
Name gender	feminine
Type	Trigonocidaris albida Agassiz, 1869, p. 263, by original designation.
Species Included	T. albida Agassiz, 1869; Recent, North Atlantic. T. albidioides Agassiz & Clark, 1907; Recent, Hawaii. T. indica Mortensen, 1942; Recent, Madagascar. T. micropora Mortensen, 1942; Recent, Indonesia. T. radiata Mortensen, 1942; Recent, Kei Islands. T. versicolor Koehler, 1927; Recent, Indian Ocean. T. monolini (Agassiz, 1879); Recent, West Pacific. T. nitidus (Doderlein, 1905); Recent, Pacific. T. sculptus Mortensen 1942; Recent, Japan, Hawaii. Trigonocidaris (Tuberculocidaris) tuberculata Markov, 1989
Classification and/or Status	Camarodonta; Temnopleuroida;Trigonocidaridae.
Remarks	The apical disc is highly characteristic having smooth genital plates with a single periproctal tubercle. This readily distinguishes Trigonocidaris from all other trigonocidarids. Mortensen, T. (1943) A monograph of the Echinoidea Part III.2, Camarodonta 1. C. A. Reitzel, Copenhagen.