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

Published online by Cambridge University Press:  28 February 2007

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

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.

Type
Life Sciences
Copyright
Antarctic Science Ltd 2007

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