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

摘要

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.