Microcardium, Thiele (1934: 878)

Poutiers, Jean-Maurice, 2006, Two new species of protocardiine cockles (Mollusca, Bivalvia, Cardiidae) from the tropical Southwest Pacific, Zoosystema 28 (3), pp. 635-654 : 643-644

While creating Microcardium, Thiele (1934: 878) failed to designate a type species but recorded two species in his new genus, Cardium (Fragum) torresi E. A. Smith, 1885 and Cardium (Fulvia) peramabilis . Later, a type species was independently and almost simultaneously designated by Keen (1937: 15) and by Dall et al. (1938: 153). Unfortunately, the latter authors chose Smith species, on the wrong basis that C. peramabilis was already attributed

Poutiers J.-M.

by Dall (1901) to Protocardia Beyrich, 1845 , a Mesozoic genus of different origin. Although this action is invalidated by Keen’s designation, it has undoubtedly contributed to misunderstand the true significance of Microcardium , and to its confusion with Frigidocardium ( Habe 1951: 152) to which C. torresi must be attributed. Thiele’s genus can be easily recognized from Frigidocardium by its heterogeneous sculpture ( Poutiers 1992: 142), its outer surface being divided in two strongly distinct sculptural areas, with spines restricted to the posterior one. Then, Tobarum cannot stand in Frigidocardium as originally proposed by Noda (1988: 74), but falls within Microcardium . Decussicardium Fischer-Piette, 1977 , invalidly introduced for the South African species Cardium gilchristi G. B. Sowerby III, 1904 (see Keen 1980; Voskuil & Onverwagt 1991), is another synonym of Microcardium .

In the Recent fauna, Microcardium is distributed on both sides of tropical America (for basic informations in this area, see Olsson 1961; Keen 1971; Abbott 1974), in addition to the Indo-West Pacific.