The reproductive cycle of the entocommensal nemertean Malacobdella arrokeana and its symbiosis with the geoduck Panopea abbreviata

S. VALERIA TESO; GREGORIO BIGATTI; M. CIELO BAZTERRICA; NESTOR F. CIOCCO; PABLO E. PENCHASZADEH

INVERTEBRATE BIOLOGY

Año: 2006 vol. 125 p. 314 - 324

1077-8306

Abstract. The reproductive cycle of the entocommensal nemertean Malacobdella arrokeana inhabiting Panopea abbreviata from San Jose´ Gulf, Patagonia, Argentina, and the nemertean– host relationship were investigated. The mature nemertean population showed a sex ratio of 1:0.64, with females predominating. The number of individuals of M. arrokeana per host varied from 1–60 individuals (mean7SD53.779.4mm). Different stages of gonadic development were observed in individual nemerteans. Spawning peaks occurred during late summer and early spring. Sexually mature individuals of both sexes were present year round, possibly indicative of a continuous breeding period. Our results suggest that M. arrokeana has no cannibalistic habits and confirm its entocommensal symbiosis with P. abbreviata.The reproductive cycle of the entocommensal nemertean Malacobdella arrokeana inhabiting Panopea abbreviata from San Jose´ Gulf, Patagonia, Argentina, and the nemertean– host relationship were investigated. The mature nemertean population showed a sex ratio of 1:0.64, with females predominating. The number of individuals of M. arrokeana per host varied from 1–60 individuals (mean7SD53.779.4mm). Different stages of gonadic development were observed in individual nemerteans. Spawning peaks occurred during late summer and early spring. Sexually mature individuals of both sexes were present year round, possibly indicative of a continuous breeding period. Our results suggest that M. arrokeana has no cannibalistic habits and confirm its entocommensal symbiosis with P. abbreviata.