Nuevos aportes a la morfología y distribución de Malacobdella arrokeana (Nemertea: Bdellonemertea), endocomensal del "geoduck" del sur, Panopea abbreviata (Bivalvia, Hiatellidae) en Patagonia (Argentina).

SERGIO R. MARTORELLI; NESTOR F. CIOCCO; M CIELO BAZTERRICA

htpp://www.civa2003.org

Congreso; Segundo Congreso Iberamericano Virtual de Acuicultura; 2003

Comite Organizador CIVA 2003

New data related to  Malacobdella arrokeana were reported based on specimens  collected in their  type host, Panopea abbreviata (Valenciennes, 1839), from Patagonia, Argentina. The mallacobdellid  nemerteans have been reported as entocommensals of many european and american bivalves from the North Atlantic and North Pacific Oceans, and only recently were reported in the Southwestern Atlantic. Malacobdella arrokeana differs from the others known species principally for  the number of intestinal undulations, the great size that it can reach, the dorso-lateral position of the excretory pore, the length of the proboscis and rynchocoel, and the position of the posterior nerve commisure.  On the basis of studies of an important number of juvenile and adult specimens new meristic data were presented and some characteristic tending to complete the description and differentiation of males, females and juvenile were reported. The original  distribution in bivalves  from the San José Gulf was extended to the San Matías Gulf and new dates related to the symbiont-host relationship were also presented.