Stochomys Thomas 1926

Stochomys Thomas 1926, Ann. Mag. Nat. Hist., ser. 9, 17: 176.

Type Species: Dasymys longicaudatus Tullberg 1893

Species and subspecies: 1 species:

Species Stochomys longicaudatus (Tullberg 1893)

Discussion: Hybomys Division. Listed as a genus by G. M. Allen (1939), but allocated to Rattus as a subgenus by Ellerman (1941). D. H. S. Davis (1965) placed Stochomys in Aethomys as a subgenus, which reflected Thomas' (1915) early allocation of longicaudatus to subgenus Aethomys . Misonne (1969) and Rosevear (1969), however, reinstated the generic status of Stochomys, correctly noting that it was distinctive and not closely related to Rattus . It has been phylogenetically associated with Dephomys (D. H. S. Davis, 1965; Misonne, 1969; an alliance supported by our study of specimens), but Van der Straeten (1984) considered it unrelated to that genus, as reflected by multivariate analysis of morphometric variation. His conclusion, however, derives from analysis of continuous variables and neglected discrete differences in character traits, and the resulting tree is a phenogram of shape-size similarity, not a cladogram reflecting shared-derived characters hypothesizing phylogenetic affinity. Features of pelage, skull, and dentition characterizing Stochomys are similar to those found in some species of Aethomys, which prompted Visser and Robinson (1986) to suggest that both belong in the same monophyletic clade in which Stochomys is the high forest partner of savanna Aethomys . Analysis of microcomplement fixation of albumin, however, grouped Stochomys and Hybomys together to the exclusion of Aethomys (Watts and Baverstock, 1995 a, b), a pairing suggested by Misonne (1969) who examined molar occlusal patterns, but not by chromosomal data (Viegas-Péquignot et al., 1986). Spermatozoal morphology is primitive for murines (Breed, 1995 a). Analyses of APRT gene sequences from Stochomys were ambiguous in assessing its cladistic position but did illuminate significance of substitution rate variation among Stochomys and other muroids (Fieldhouse et al., 1997). Additional inquiry into the phylogenetic affinity of Stochomys is warranted, employing broader generic sampling and analyses of mitochondrial and nuclear gene sequences.