MOLAR SURFACE-MORPHOLOGY IN STREPTOCEPHALUS-COOMANSI (CRUSTACEA, BRANCHIOPODA, ANOSTRACA)

Except for the posterio-dorsal margin, the circumference of the molar surface exhibits flagellated processes which become simple at the post erio-ventral margin. Four topographic regions are distinguished: A) a postero-dorsal region, B) a peripheral region, C) a transitional zone, and D) a central region. The postero-dorsal region of the left mandib le has one row of widely spaced, stout, conical teeth, while in the ri ght mandible two rows of slender teeth, which become multi-branched an teriorly, are present. The peripheral molar region stretches between t he bordering flagellated processes and the central region and consists of several parallel, dorso-ventral rows of armed teeth. The maximum n umber of teeth in one dorso-ventral row is higher at the ventral than at the dorsal side and in the left than in the right mandible. In the transitional zone, the number of cusps on each tooth is progressively reduced. The central region, a perforated thickened cuticular plate, e xtends over the majority of the molar surface. This region is unique a mong the anostracans studied in this respect and may reflect a differe nt feeding ecology. The strongly diversified molar surface probably al lows the species to exploit a wide trophic spectrum. It remains to be tested if these observations may be extrapolated to the entire genus. (C) 1994 Wiley-Liss, Inc.