Morphological variation in some populations of Systomus sarana in Sri Lanka and a comparative analysis with Systomus sarana from Kerala-India

Abstract

The freshwater cyprinid fish that has long been identified as Systomus sarana (Puntius sarana) is a widespread species in Sri Lanka. Taxonomic complexity of this species has been indicated by previous literature, but no scientifically confirmed information is available on phenotypic variation of the species, and whether the Sri Lankan species is in fact similar or different from Indian S. sarana (s.l.). The present study aimed to describe the morphometric and meristic characters of S. sarana (s.l.) in Sri Lanka, and to carry out a comparative analysis with S. sarana from Kerala. High degree of variation in morphology was evident among some of the studied populations (Menik River- M, Kirindi Oya-KO, Nilwala River-N, Kelani River-K, Walawe River-WP, Malwathu Oya-MO, Gin River-G and Kerala/India-IK). Univariate ANOVA showed that, except Pre Doral Length, Post Dorsal Length, Caudal Peduncle Depth and Maximum Body Depth, all the other characters were significantly different (P<0.05) among studied populations. Discriminant function analysis identified post orbital length as having the greatest power to discriminate the populations. Significant separation of two groups of populations was possible by canonical analysis, where CV1 and CV2 explained 69.7% of the total variation in data. In cluster analysis, MO, K and IK populations create a separate clade which probably shows a lineage splitting from the other clade (M, KO, N, WP, and G) by having a linkage distance of -85%. Results from meristic counts were also in agreement to this separation where number of scale rows above lateral line was different between the two clades (4 Vi vs. 5 Vi). The results conclude that at least two clearly differentiable groups of this fish are present in Sri Lanka, and one of which (MO and K) shares the characters of Indian S. sarana more closely than the other group (M, KO, N, WP, and G).