Abstract
A systematic survey of the western Corsican shelf and slope was made, during which we collected on the border of the Continental Shelf an important number of Sclerasterias richardi (Perrier, 1882), a relatively deep-sea asteroid, considered to be fairly rare. After summarizing and enlarging earlier data concerning the distribution of this species, the present paper, based upon the most recent collections (July, 1974), describes some morphological features of the species as seen under the scanning microscope and provides the first histological description. Study of the gonads revealed that S. richardi is gonochoric; ovocytes have synchronous growth, and spermatogenesis is cyclic. However, the observed reproduction, together with the first biometric data indicate that, for the specimens studied, there is no relation between size, sex, degree of maturity and number of arms. The specimens examined are not the juvenile fissiparous stages of an unknown 5-rayed adult as formerly hypothesized. Moreover, fissiparity, which occurs always in this seastar, is here concomitant with sexual reproduction. Study of the reproductive cycle will enable the periodicity of the emission of sexual products to be determined. Rearing of collected specimens in the laboratory will allow artificial fecundation, by which means the as yet unknown larvae may be obtained.
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