The Echinoid Directory

Nudechinus H. L. Clark, 1912, p. 276

[= Cyrtechinus Mortensen, 1942, p. 229, type species Psammechinus verruculatus Lutken, 1864 ]

Diagnostic Features	Small, hemispherical test. Apical disc often, but not invariably, hemicyclic. Periproct central, with a few large periproctal plates. Ambulacra trigeminate with pore-pairs in arcs of three forming a single band. Interambulacra with central primary tubercle and usually with row of secondary tubercles on either side. Peristomial membrane naked except for the ten buccal plates. Auricles fused perradially.
Distribution	Recent; Indo-West Pacific.
Name gender	masculine
Type	Nudechinus scotiopremnus Clark, 1912, p. 276, by original designation.
Species Included	N. scotipremnus Clark, 1912; Recent, Red Sea and Western Australia. N. multicolor (Yoshiwara, 1898); Recent, Japan. N. ambonensis Mortensen, 1942. Recent, West Pacific. N. stictus Clark, 1912; Recent, Sulu Archipelago. N. gravieri (Koehler, 1905); Recent, Gulf of Aden and Western Australia. N. rubripunctatus Clark, 1925; Recent, Amirante Islands. N. darnleyensis (Tenison Woods, 1878); Recent, Australia. N. inconspicuus Mortensen, 1904. Recent, West Pacific
Classification and/or Status	Camarodonta; Echinoida; Toxopneustidae. ?Monophyletic.
Remarks	The only difference that separates Nudechinus from the monotypic Cyrtechinus is that Nudechinus has generally a rather naked peristomial membrane, whereas in Cyrtechinus the peristomial membrane is densely plated. However, as Mortensen (1943, p. 393) pointed out, Nudechinus ambonensis is intermediate between the two and there seems no real justification for maintaining the two at generic level. Clark, H. L. 1912. Hawaiian and other Pacific Echini. The Pedinidae, Phymosomatidae, Stomopneustidae, Echinidae, Temnopleuridae, Strongylocentridae and Echinometridae. Memoirs of the Museum of Comparative Zoology 34(4), 205-383. Mortensen, T. (1943) A monograph of the Echinoidea Part III.2, Camarodonta 1. C. A. Reitzel, Copenhagen.