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Antarctic Science

Table of Contents - 2007 - Volume 19, Issue 01  


Life Sciences

Gametogenesis in the dragonfishes Akarotaxis nudiceps and Bathydraco marri (Pisces, Notothenioidei: Bathydraconidae) from the Ross Sea

Mario La Mesa a1c1, Vincenzo Caputo a2 and Joseph T. Eastman a3
a1 ISMAR-CNR, Istituto di Scienze Marine, Sede di Ancona, Largo Fiera della Pesca, 60125 Ancona, Italy
a2 Istituto di Biologia e Genetica, Universitá Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy
a3 Department of Biomedical Sciences, College of Osteopathic Medicine, Ohio University, Athens, OH 45701-2979, USA

Article author query
la mesa m   [PubMed][Google Scholar] 
caputo v   [PubMed][Google Scholar] 
eastman jt   [PubMed][Google Scholar] 

Abstract

We analysed histological characteristics of gonads and reproductive effort of the small deep-living dragonfishes Akarotaxis nudiceps (Waite) and Bathydraco marri Norman collected in the south-western Ross Sea. From a macroscopic point of view, most specimens of B. marri were juveniles in early stages of gonad maturity, except for a maturing female. Conversely, the sample of A. nudiceps was composed of both immature and adult fish in different stages of maturity. A single A. nudiceps female was mature with a gonadosomatic index of 9.8%. Its absolute and relative fecundity was 260 oocytes and 31.5 oocytes g−1 TW, respectively, with a mean size of ripe oocytes of 1.9 mm. Gametogenesis in both species closely resembled that observed in other notothenioids, with females possessing two well-defined groups of oocytes. One group consisted of previtellogenic oocytes as a reserve stock while the other group was maturing oocytes to be ovulated in the current spawning season. A distinctive feature of oogenesis in recovering and maturing females of A. nudiceps was the presence of both postovulatory follicles in different stages of reabsorption and atretic oocytes. Based on low absolute fecundity, it is possible that A. nudiceps provides parental care and egg guarding.

(Published Online February 28 2007)
(Received May 18 2006)
(Accepted August 7 2006)


Key Words: Antarctica; bathydraconid; histology; oogenesis; reproduction; spermatogenesis.

Correspondence:
c1 m.lamesa@ismar.cnr.it

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