Crossarchus obscurus, F. G. Cuvier, 1825

Don E. Wilson & Russell A. Mittermeier, 2009, Herpestidae, Handbook of the Mammals of the World – Volume 1 Carnivores, Barcelona: Lynx Edicions, pp. 262-328 : 324-325

27.

Common Cusimanse

Crossarchus obscurus

French: Mangouste brune / German: Dunkelkusimanse / Spanish: Cusimansé del Niger

Other common names: Cusimanse, Long-nosed Cusimanse

Taxonomy. Crossarchus obscurus Cuvier, 1825 ,

Sierra Leone.

Separation from C. platycephalus is based upon skull morphology, but with some doubts. Monotypic.

Distribution. W Africa in Guinea, Sierra Leone, Liberia, Ivory Coast, and Ghana.

Descriptive notes. Head-body 30-37 cm, tail 14-621 cm, hindfoot 6.7-3 cm, ear 2.2-6 cm; weight 0-45. 1 kg. Similar in size to Flat-headed Cusimanse, but lacks crest of hair between the ears and neck on the midline (in Flatheaded Cusimanse), and lacks whorls of hair present on the neck of Alexander’s Cusimanse. Dark shaggy brown to black fur; pale underfur. Fur on head and face is shorter and lighter. Dense underfur is lighter than the dorsal guard hairs. Dorsal guard hairs 10-15 mm at nape, gradually lengthening towards rump (30-35 mm). Long, snout-like nose ends substantially beyond lower lip. No longitudinal groove on upperlip. Short, rounded ears, capable of closing via movement of posterior ridges. Pupils are horizontally elongated. Relatively short tail and short legs. Well-developed claws on forefeet. Five digits on foreand hindfeet. Hindfoot soles naked except last third toward heel. No obvious sexual dimorphism. There are three pairs of mammae. Cheek glands present. Skull long and narrow with elongate rostrum. Condylobasal 64-8-75 mm. Rostrum 22-2-26-7 mm. Zygomatic breadth 32-2-37-9 mm. Ectotympanic bullae inflated less than entotympanic bullae. Dental formula: 13/3,C1/1,P 3/3, M 2/2 = 36.

Habitat. Dense undergrowth of rainforest and riparian forest, but also in logged forest and plantations. Ranges from sea level to 1000 m (in Sierra Leone) and 1500 m in Mount Nimba ( Guinea).

Food and Feeding. Feeds on invertebrates and vertebrates of the forest floor and in rotting logs. Invertebrate prey includes snails (Gastropoda), earthworms (Oligochaeta), spiders (Arachnida), crabs (Decapoda), woodlice (Isopoda), centipedes (Chilopoda), millipedes (Diplopoda), grasshoppers and crickets (Orthoptera), cockroaches (Blattaria), beetles ( Coleoptera ), mason wasp larvae (Eumenidae). Vertebrate prey includes frogs, snakes, lizards (including eggs), birds (including eggs and nestlings), and small mammals (up to size of Greater Cane Rat Thyronomys swinderianus). Fruits and berries are also consumed. Forages by scratching and rooting using claws and snout. Small mammals are killed with a bite to back of the neck. Invertebrate prey apparently shaken before consumption.

Activity patterns. Believed to be mainly diurnal, but some night activity reported. Forages in dense vegetation. May excavate own burrows. Has been observed to spend the night above-ground in trees.

Movements, Home range and Social organization. Social. Groups of up to 20 or more appear to rove, with no fixed dens, sleeping in burrows, under logs or in dense vegetation. Some climbing and shallow water foraging observed. Said to wander through their home range, rarely seen for more than a few days in the same place. Elaborate vocal repertoire; group members keep in contact with contact chirps, churrs, and twitters. Substantial difference in chemical composition between male and female anal sac secretions (female secretions contain compounds absent in male). Both sexes scent-mark using cheek and anal glands. Play behavior said to be common in captivity and wild.

Breeding. Polyestrous in captivity. Apparently induced ovulation. The male initiates copulation by first mounting the female with his forelegs forward of her pelvic region, then grasps the female at back of the neck and begins thrusting. Littersize two to four (usually four). Up to three litters per year in captivity. Mean gestation for three captive litters was 58 days. Altricial young, born with underfur, but eyes closed (head and body 9-10 mm). In captivity, eyes opened at twelve days and weaning occurred at three weeks. Young are probably sexually mature at approximately nine months. Longevity nine years in captivity. Predators likely include large carnivores and raptors (e.g. the crowned hawk eagle, Stephanoaetus coronatus).

Status and Conservation. Not CITES listed. Classified as Least Concern in The IUCN Red List. Apparently common within its range, but heavily hunted and vulnerable to hunting dogs. The Common Cusimanse is one of the least known of the social mongooses and field studies are required (current information principally based upon captive animals).

Bibliography. Coetzee (1977), Colyn & Van Rompaey (1990), Decker et al. (1992), Ewer (1973), Goldman (1984, 1987), Goldman & Dunham (In press), IUCN (2008), Kingdon (1997), Van Rompaey & Colyn (1992), Wozencraft (2005).

Figures

On following pages: 25. Alexander's Cusimanse (Crossarchus alexandri); 26. Angolan Cusimanse (Crossarchus ansorgel); 27. Common Cusimanse (Crossarchus obscurus); 28. Flat-headed Cusimanse (Crossarchus platycephalus); 29. Ethiopian Dwarf Mongoose (Helogale hirtula); 30. Common Dwarf Mongoose (Helogale parvula); 31. Pousargues’s Mongoose (Dologale dybowskii): 32. Liberian Mongoose (Liberiictis kuhni); 33. Gambian Mongoose (Mungos gambianus); 34. Banded Mongoose (Mungos mungo).

Distribution. W Africa in Guinea , Sierra Leone , Liberia , Ivory Coast , and Ghana .