The endemic Iranian Cave-fish,<i>Iranocypris typhlops</i>: two taxa or two forms based on the mental disc?

Abstract

Abstract The objective of this study was to investigate morphometric and meristic characteristics of Iranocypris typhlops, comparing new material having a mental disc with those lacking a disc. 24 morphometric and 9 meristic variables were measured. Statistical analyses used cluster and discriminant methods, which showed significant morphometric differences between the two groups (Wilk’s Lambda, p<0.05). Additionally, fish with a disc had less pectoral and pelvic rays compared to fishes without a disc. Fishes without a disc generally had a bipartite swimbladder; in contrast, fishes with a disc had unipartite and bipartite swimbladders in an equal ratio. There may also be some differences in feeding habits between these two groups. Fish with a disc can attach to and graze on the substrate. A significantly longer intestinal length in fishes with a disc may also be indicative of a detrital feeding habit.