Journal of the Marine Biological Association of the United Kingdom

Table of Contents - 2009 - Volume 89, Issue 01  

Cambridge Journals Online - CUP Full-Text Page
Journal of the Marine Biological Association of the United Kingdom (2009), 89:161-169 Cambridge University Press
Copyright © Marine Biological Association of the United Kingdom 2009
doi:10.1017/S0025315408002397

Research Article

Reproductive characteristics of Calyptogena gallardoi (Bivalvia: Vesicomyidae) from a methane seep area off Concepción, Chile

Macarena Parraa1, Javier Sellanesa1a2 c1, Enrique Dupréa1 and Elena Krylovaa3

a1 Universidad Católica del Norte, Facultad de Ciencias del Mar, Departamento de Biología Marina, Larrondo 1281, Coquimbo, Chile
a2 Centro de Investigación Oceanográfica en el Pacífico Sur-Oriental (COPAS), Universidad de Concepción, Casilla 160-C, Concepción, Chile
a3 P.P. Shirshov Institute of Oceanology, Nakhimovskii Precinct, 36, Moscow, 117851, Russia
Article author query
parra m [PubMed]  [Google Scholar]
sellanes j [PubMed]  [Google Scholar]
dupré e [PubMed]  [Google Scholar]
krylova e [PubMed]  [Google Scholar]

Abstract

Calyptogena gallardoi is a vesicomyid bivalve inhabiting a methane seep area located at a depth of 740–870 m off the Bay of Concepción, Chile. Vesicomyids host chemoautotrophic sulphide-oxidizing endosymbiont bacteria and are always found associated to reducing environments. In this study, the gonadal structure and the gametes produced by C. gallardoi are described. Light microscopy is used to examine serial histological sections of the gonads, and scanning electron microscopy is used to visualize the external morphology of gametes. The gonads of both males and females are organized in ramified tubular acini. In males, mature sperm are stored near genital openings in acini lined with a secretor epithelium that resembles a seminal receptacle. Spermatozoids have bullet-like heads with an average length of 30.3±2.6 μm (mean±1 SD). In females, the mature oocytes are driven toward the genital opening through evacuator conduits lined by ‘paddle’ cilia. The average diameter of oogonias is 11.6±2.5 μm and that of mature oocytes is 273.8±23.1 μm, making the size of the mature oocyte among the largest reported for bivalves. In addition, C. gallardoi is shown to have external sexual dimorphism. Shells of males are significantly smaller and more elongated with sloping postero-dorsal margin compared with shells of females. The data are discussed in the context of available information on reproductive biology of vesicomyids.

(Received March 12 2008)

(Accepted June 03 2008)

Keywordsbivalve reproduction; Calyptogena; Vesicomyidae; gametogenesis; methane seep; south-eastern Pacific

Correspondence:

c1 Correspondence should be addressed to: Javier Sellanes, Universidad Católica del Norte, Facultad de Ciencias del Mar, Departamento de Biología Marina, Larrondo 1281, Coquimbo, Chile email: sellanes@ucn.cl