No abstract

Documentation of genetic differentiation among the populations of a species can provide useful information that has roles in conservation, breeding, and management plans. In the present study, we examined the genetic structure and phylogenetic relationships among the 149 individuals of Ompok bimaculatus belonging to 24 populations, collected from Indian waters, using cytochrome b gene. The combined analyses of data suggested that the Indian O. bimaculatus consist of three distinct mtDNA lineages with star-like haplotypes network, which exhibited high genetic variation and haplotypic diversity. Analysis of molecular variance indicated that most of the observed genetic variation was found among the populations suggesting restricted gene flow. Long-term interruption of gene flow was also evidenced by high overall Fst values (0.82367) that could be favored by the discontinuous distributions of the lineages.

The silurid butter catfish, Ompok bimaculatus (Bloch, 1794), is widely distributed in the plains and sub-mountain regions of India, but not enough is known about its reproductive potential is still insufficient. The present study evaluated the comparative reproductive potential (in terms of sex ratio, spawning season, body size at first go­nadal maturity, gonadosomatic index, fecundity, egg dimension, egg weight etc.) of fish (n=1223) from six tropical tributaries of the Ganges basin during January 2011-December 2013. The females had relatively greater weight and length. The body size at 50% first gonadal matu­rity (L50%) ranged between 228-262mm in females and 198-247mm in males. The population has high and low fecundities. The correlations between absolute fecundity and total length, as well as between body weight and gonad weight, were significant (p<0.05) and positive in all the population.

This study demonstrates the comparative pattern of reproductive parameters viz. sex ratio, size at first gonadal maturity, gonadosomatic index (GSI), fecundity, egg dimension of O. bimaculatus analyzed from 13 different rivers during 2011-2013. It was observed that females start to mature earlier than males and mean size at first maturity in male and female varied considerably between the different populations. The reproductive period of fish were extended from April -August while in Southern rivers it was extended from March to July. The results indicated three types of reproductive patterns of O. bimaculatus in terms of age at first sexual maturity and absolute fecundity and distinct variation was observed across different rivers. The meanabsolute fecundity varied significantly between the rivers and was grouped in to three categories: (i) high absolute fecundity (ii) medium fecundity and (iii) low fecundity. The results indicated significant and positive correlation between absolute fecundity and total length, body weight and ovary weight in all the rivers (P<0.05). The oocyte distribution during the maturity season was consistent within the ovary but more fluctuations were observed within different population. This study provides quantitative account in to the comparative reproductive potential and inter-population reproductive strategies for the first time.

RESUMEN: Los peces bagre del género Glyptothorax se distribuyen ampliamente, con nada menos que 40 especies nominales reportadas en India, donde normalmente habitan en arroyos de montaña con corrientes rápidas y tramos que fluyen más rápido en ríos y arroyos mas grandes. Registramos una nueva distribución biogeográfica de tres especies de Glyptothorax de las afluentes de las llanuras del norte de la cuenca del Ganges. Los especímenes se recolectaron durante la pesca experimental para estudios de biodiversidad con atarraya (2010-2012). Mientras que G. conirostris se capturó en el canal del río Ganges, G. cavia y G. telchitta fueron capturados en el río Gomti. Descripciones anteriores son basadas en especímenes preservados, presentamos características diagnósticas y redescripción ilustrada basada en especímenes frescos.PALABRAS CLAVE: nueva distribución, Glyptothorax conirostris, G. telchitta, G. cavia, cuenca Ganges, India