Abstract
Lissocidaris xanthe sp. nov. Coppard & van Noordenburg, 2007 occurs at depths of between 150 m and 250 m near Mactan Island in the Philippines. It is distinctive in having aboral interambulacral spines that measure more than twice the test’s horizontal diameter at the ambitus. The neck of each spine is typically white and unconstricted. Oral primary interambulacral spines have serrated edges. Large globiferous pedicellariae have moderately narrow valves, each valve with a narrow longitudinally oval opening beneath a large terminal tooth. It is similar to the type species of Lissocidaris (L. fusca) in having smooth, aboral interambulacral spines, the smooth surface formed by dense, anastomosing cortical hairs that coalesce to form a continuous crust between longitudinal ridges. Smooth spines are also found in two other cidaroid genera: Calocidaris and Compsocidaris. However, in these genera, the glossy surface results from the cortex being devoid of hairs; this provides a marked example of convergent evolution.References
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