Phylogenetic Relationships of African Killifishes in the Genera
Aphyosemion and Fundulopanchax Inferred from Mitochondrial DNA Sequences.
"The African genera show by far the greatest karyological
variability—the most striking case found within the
genus Aphyosemion (Scheel, 1990). Of the eight defined
species groups, three (bivittatum, calliurum, and elegans)
contain taxa with karyotypes ranging from n 5
18 to n 5 9 or 10 (Fig. 4). The remaining species groups
show much less variability in chromosome number and
morphology. One of the more notable findings from this
study is that the species groups showing reduced
karyotypes are not phylogenetically restricted. Rather,
this propensity toward reduced karyotypes has occurred
multiple times in Aphyosemion. A similar extreme
reduction in haploid number has occurred in
Nothobranchius rachovii (n = 9/18 arms; Scheel, 1972,
1990). This trend is particularly striking because the
populations having n = 9 to 10 in Aphyosemion (14)
outnumber all other nonaplocheiloid teleosts having
such reduced chromosome numbers: the bristlemouth
Gonostoma bathyphilum (Gonostomatidae), n = 6; the
gouramie Sphaerichthys osphromonoides (Belontiidae),
n = 8; (Sola et al., 1981).
