Description

Description. Test wider than long (TL = 71.7 mm; TW = 78.7 mm), with thin ambitus, domed anteriorly, highest point of test located slightly anterior to apical system and curving down abruptly to anterior margin (Fig. 12 A, C). Apical system monobasal, with four gonopores (Fig. 12 I). Petaloid large, corresponding to a little more than 50 % TL (Fig. 12 A, C). Posterior petals slightly longer than anterior ones (Fig. 12 A, C). Five lunules, anal lunule longer than paired ambulacral lunules (Fig. 12 A – D). Aboral primary spines short and club-shaped, covering the test uniformly (Fig. 12 A, H). Each Miliary spines each with sac-like structure on tip, densely scattered among primary spines. Lunules with two types of spines: aboral ones longer, flat and enlarged at tip (similar to swim fins). Inner spines elongate and tapering. Oral surface flat, with long, thin locomotory spines that are slightly curved at the base, occupying the centre of interambulacra (Fig. 12 b, D). Geniculate spines short and slightly curved, in fields from margins of interambulacra to margins of food grooves. Among these are long, slender spines in areas near pressure drainage channels (Fig. 12 B). Peristome pentagonal and slightly anterior (Fig. 12 B, D). Periproct oval to triangular, very close to peristome, deeply indenting basicoronal plate (Fig. 12 B, D). Periproctal membrane covered by large plates of different sizes and shapes. Interambulacral basicoronal plates longer than ambulacral ones. Food grooves bifurcating at distal edges of ambulacral basicoronals and highly branched distally (Fig. 12 D). Pedicellariae. Pedicellariae scattered over entire test, being more abundant in oral interambulacra and in areas close to lunules, peristome, and periproct. Bidentate pedicellariae with a long neck (as long as or shorter than stalk) and short head. Valves short, with narrow and slightly curved, median region enlarged, margin slightly serrate, and a terminal tooth that crosses with the tooth of the opposing valve (this tooth is seen only in the larger pedicellariae) (Fig. 12 E – G). Colour. Greenish or brownish (Fig. 12 A, B, 19 F). Naked test white (Fig. 12 C, D).

Common Names

Taxonomic Hierarchy

Kingdom: Animalia

Phylum: Echinodermata

Class: Echinoidea

Order: Echinolampadacea

Family: Mellitidae

Genus: Mellita

Species: Mellita quinquiesperforata (Leske, 1778)