Grammomys Thomas, 1915

Denys, Christiane, Lalis, Aude, Lecompte, Émilie, Cornette, Raphaël, Moulin, Sibyle, Makundi, Rhodes H., Machang, Robert S., Volobouev, Vitaly & Aniskine, Vladimir M., 2011, A faunal survey in Kingu Pira (south Tanzania), with new karyotypes of several small mammals and the description of a new Murid species (Mammalia, Rodentia), Zoosystema 33 (1), pp. 5-47 : 19-21

publication ID 10.5252/z2011n1a1

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Grammomys Thomas, 1915


Genus Grammomys Thomas, 1915

The narrow-footed thicket rats of the genus Grammomys are arboreal rodents with very long tails ending with fine hairs at the tip. They differ from Thamnomys in dental characters ( Thomas 1915; Heim de Balsac & Aellen 1965; Misonne 1969; Rosevear 1969): postero-internal or “x” cusp of the first and second molars reduced to a mere connecting ridge running from the inner cusp of the median lamina to the hinder point of the tooth ( Thomas 1915: 150) and by having a wider and shorter hindfoot ( Hutterer & Dieterlen 1984). According to Kingdon (1974), G. dolichurus (Smuts, 1832) is found in Tanzania but it may be represented by three different forms, which have subsequently been elevated to species rank by Hutterer & Dieterlen in 1984. These forms are G. cometes (Thomas & Wroughton, 1908) , G. dolichurus and G. macmillani (Wroughton, 1907) . These authors also described a new species of the G. dolichurus complex: G. caniceps Hutterer & Dieterlen, 1984 from north Kenya and south Somalia. Based on their morphology, Meester & Setzer (1971 -1977) keep the distinction between Grammomys and Thamnomys by using t7 cusp disposition on the upper M1/. They also provide a character to distinguish between G. rutilans Peters, 1876 (small t7 but visible) from G. cometes / G. dolichurus (crestiform t7 relating t4 to t8). Later, Petter & Tranier (1975) showed that the morphology of the upper M3 molar reflects the important karyotypic diversity observed in the G. dolichurus group and recognized the distinction of the CAR G. gazellae (Thomas, 1910) today synonymyzed with G. macmillani . Musser & Carleton (2005) confirmed the distinction of the genus Grammomys and following Hutterer & Dieterlen (1984), restricted G. dolichurus to eastern and southern Africa, including subspecies in the montane areas of Nyika, Kilimanjaro and Elgon. The holotype of G. dolichurus , which is the type species of genus Grammomys , comes from Cape Town.No precisions about G. dolichurus occurrence in Tanzania are reported and limits of its geographical range remain unresolved according to Musser & Carleton (2005). However, in Malawi, Hanney (1965) described G. dolichurus and G. cometes in south Malawi and Nyika Plateau. Grammomys cometes was described from a specimen from Inhambane, Mozambique and would be distributed according to Musser & Carleton (2005) from SE Cape Province and Mozambique south of the Zambezi river, and is an inhabitant of the savannah woodland biome in South Africa ( Mugo et al. 1995). Grammomys macmillani , described from Ethiopia, would be present from Sierra Leone to Mozambique according to Musser & Carleton (2005). This range extension of the species, compared to that indicated by Hutterer & Dieterlen (1984), is based only upon morphology and it includes G. gazellae representatives of CAR karyotyped by Petter & Tranier (1975). Also based upon morphological analysis of type specimens, Musser & Carleton (2005) contrary to Hutterrer & Dieterlen (1984) rehabilitated G. ibeanus Osgood, 1910 from Kenya and separated it from G. cometes series. According to Wilson & Reeder (2005), G. ibeanus would be distributed from extreme NE Zambia, Malawi to highlands of eastern Tanzania and Kenya to southern Sudan. In Zambia and Tanzania, the complex G. surdaster Thomas &Wroughton, 1908 , that has been put in synonymy with G. dolichurus by Musser & Carleton (2005), should comprise at least two chromosomal formulae (2n = 50-51, FNa = 61 and 2n = 42, FNa = 64), as described by Corti et al. (2005). For these authors, some Tanzanian specimens assigned to the G. butingi complex, without justification, would display a new karyotype. Finally, a new species of the genus was recently described in Kenya: G. brevirostris Kryštufek, 2008 .