Scale structure variability of “forms flock” of Barbus (=Labeobarbus) intermedius and Varicorhinus jubae from the Genale River (Eastern Ethiopia)

Abstract

Scales sculpture of 6 morphotypes of large African barbs Barbus (=Labeobarbus) intermedius and Varicorhinus jubae from the Genale River were described using light and scanning electron microscopy (SEM). It was found that in spite of several trends in difference macrostructural scale parameters (shape and lateral line scales number), cannot be used for identification of most forms of barbs and V. jubae of the Genale River. SEM analysis of scale microstructure of large barbs, V. jubae and V. beso has showed that the relief of the caudal field of the scales is not uniform and four main zones may be distinguished. The differences between forms and species in the relief details are weakly expressed however the studied species may be arranged in succession according to the development of specific; characters in transitional Zone II: B. intermedius (5 forms: GF, LMP, SH, LMS, LIP) > “smallmouth scraper” form—probable hybrid B. intermedius × V. jubae (SMS) > V. jubae > V. beso. By the development of granulation zone III the following series may be suggested: B. intermedius (5 forms: GF, LMP, SH, LMS, LIP), V. jubae > “smallmouth scraper” formprobable hybrid B. intermedius × V. jubae (SMS) > V. beso. By the degree of founded “trabecular” structure development the following series may be arranged according to the character reduction: B. intermedius (GF, LMP, SH, LMS, LIP) > “smallmouth scraper” form-probable hybrid B. intermedius × V. jubae (SMS) > V. jubae > V. beso. Thus in accordance with scale microstructure Varicorhinus jubae closer to Barbus (=Labeobarbus) intermedius than to V. beso.