On two allied species of the genus Diastylis form southern South America (Crustacea: Cumacea: Diastylidae).

MORETTI, A.N.; ROCCATAGLIATA, D.

Coquimbo, Chile

Congreso; .“The Crustacean Society Mid-Year Meeting”; 2007

Universidad Católica del Norte

Diastylis is the oldest genus of Cumacea and contains a large number of species (about 100). Besides, this genus is very variable, including species with two or three articles on the endopod of the uropods. Up to date, only two Diastylis with two articles on their uropodal endopods have been described from the southern South America, i.e., D. argentata Calman, 1912 and D.  granulata Zimmer, 1921. The former was described on the basis of many males and females obtained in the Golfo de Penas, and more recently it was collected at the east entrance of the Beagle Channel and south of it. This species is herein briefly redescribed and its northern limit of distribution extended to Puerto Montt. D. granulata was previously known from a single subadult male collected south of the Río de la Plata mouth during the Swedish Eugenie-Expedition (1851-53), and has not been reported again since its original description. The adult male and female of this species are herein fully described on the basis of specimens collected near its type locality. These two allied species can be easily distinguished by the arrangement of their carapace sculpture: D. argentata bears a row of teeth extending backwards without reaching the anterolateral horn, whereas D. granulata has an arched row of teeth that ends on each anterolateral horn. SEM photographs showing the carapaces sculpturing of these two species are provided. This research was partially supported by the University of Buenos Aires (UBACyT X162), the ANPCyT (PICT 02/11180) and the CONICET (Argentina).