Abstract:
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Morphological revision was made on thirty specimens of Ichthyborus besse besse, and thirty specimens
of Ichthyborus besse congolensis, taken from the collection of the Royal Museum for Central Africa in Belgium. The
aim of this study is to verify the taxonomic status of the two subspecies and determine the morphological
characters that characterize the ecological populations of I. besse besse from Cameron, Central Africa, and Congo
and Schad basins, in their natural range. Variations of 23 morphometric measurements and 10 meristic counts
were examined and compared. Principal component analysis along with discriminate analysis indicated that the
most important morphometric characters that distinguish I. besse bessefrom I. besse congolensis are the snout
length (SNL), body depth (BD), the origin of the pelvic (PRPV), anal (PRAN) and pectoral (PRP) fins, caudal
peduncle length, in addition the number of: teeth in the upper jaw (TUJ) and the lower jaw (TLJ), scales around
the caudal peduncle (CPS), number of scales in the lateral line (LLS). Cluster analysis of morphometric
measurements produced a hierarchical cluster separating all individuals of I. besse besse from individuals of I.
besse congolensis. Discriminate analysis of the ecological populations of I. besse besse revealed that the caudal fin
length (CFL) and body depth (BD) have the bigger loads in separating the ecological populations followed by the
inter-orbital width (IOW), eye diameter (ED), dorsal-to-adipose distance (DAD) and snout length (SNL), in addition
to the number of teeth in lower jaw (TLJ) and upper jaw (TUJ). Cluster analysis of meristic counts gave better
separation of the ecological population of I. besse besse than the morphometric measurements. A detailed
description of I. besse besse and I. besse congolensis according to this study is given. |