Malacomys Milne-Edwards 1877

Malacomys Milne-Edwards 1877, Bull. Sci. Soc. Philom. Paris, ser. 6, 12: 10.

Type Species: Malacomys longipes Milne-Edwards 1877

Species and subspecies: 3 species:

Species Malacomys cansdalei Ansell 1958

Species Malacomys edwardsi Rochebrune 1885

Species Malacomys longipes Milne-Edwards 1877

Discussion: Malacomys Division. Study of dental features led Misonne (1969:106) to write that " Malacomys stands apart from all the other African genera by its unusual dental characters. This is an advanced genus which cannot be clearly related to any other one." Malacomys was included in allozymic analyses, which were inconclusive as to detecting its closest relative (Bonhomme et al., 1985). DNA/DNA hybridization experiments (Chevret, 1994) clustered Malacomys longipes as one branch of a trifurcation with the second leading to a " Praomys group" ( Praomys + Myomys + Mastomys + Hylomyscus) and the third to a " Mus group" ( Mus, including subgenera Pyromys, Nannomys, and Coelomys). External, cranial, and dental traits suggest Malacomys is phylogenetically allied with Praomys, particularly through what appears to be the morphologically annectant P. lukolelae and P. verschureni (our study of specimens; see account of P. lukolelae). This view is countered by the cladistic analyses of morphological traits in species of Praomys, Hylomyscus, Mastomys, and Myomyscus (reported as Myomys) where Malacomys was used as an outgroup and was consistently excluded from a monophyletic " Praomys group" (Lecompte et al., 2002 a), and "was always very distant from the ‘ Praomys group’, even when not designed as outgroup in parsimony or any other type of analyses" (L. Granjon, in litt., 2002). Malacomys is also distant to monophyletic Praomys group in preliminary results from phylogenetic analyses of nuclear IRBP gene sequences (E. Lecompte, in litt., 2002). Analyses of a broader range of genes along with denser taxon sampling that includes Malacomys would be welcome and may provide a sharper picture of its phyletic affinity within a reconstruction of phylogenetic relationships among African murines.

Two revisions (Rautenbach and Schlitter, 1978; Van der Straeten and Verheyen, 1979 b) provided somewhat different evaluations of morphological variation and its interpretation in context of species-diversity. The morphological distinctions between M. edwardsi and M. longipes were documented more than six decades ago by Hayman (1935). Geographic distributions outlined below come mostly from the two revisions.

Species of Malacomys are referred to as African swamp rats (Wilson and Cole, 2000), but they do not inhabit swamps. Their range of habitats is exemplified by the sympatric range of M. edwardsi and M. cansdalei in Ghana. Both eat slugs, earthworms, and plant parts, and require primary tropical evergreen rainforest, but M. edwardsi is found in higher, well drained ground, and M. cansdalei prefers damper places – valley bottoms, moist lower slopes, stream banks, and wet mud (Grubb et al., 1998; Happold, 1987). Malacomys edwardsi has been caught on moist soil near a river in SW Guinea (Barnett et al., 1996). In the Kalinzu Forest of SW Uganda, M. longipes was collected on dry ground around stumps in logged forest (Lunde and Sarmiento, 2002), and Granjon (1991) trapped it in a variety of habitats in Republic of Congo, from degraded primary forest to swamp forest. In their experience, Kerbis Peterhans and Patterson (1995) noted that M. longipes was usually captured in shallow forest streams or along their margins (also indicated by Hoffmann, 1997). They included species of Malacomys, Colomys goslingi, and Deomys ferrugineus in an African guild of waders (see account of Colomys).