Rhynchocyon chrysopygus, Gunther, 1881

Russell A. Mittermeier & Don E. Wilson, 2018, Macroscelididae, Handbook of the Mammals of the World – Volume 8 Insectivores, Sloths and Colugos, Barcelona: Lynx Edicions, pp. 206-234 : 227

1.

Golden-rumped Seng

Rhynchocyon chrysopygus

French: Sengi a croupe dorée / German: Goldsteil 3-Riisselhiindchen / Spanish: Sengi de grupas doradas

Other common names: Golden-rumped Elephant-shrew, Golden-rumped Giant Sengi, Yellow-rumped Elephant-shrew, Yellow-rumped Sengi

Taxonomy. Rhynchocyon chrysopygus Gunther, 1881 ,

“ on the river Mombaca [= Mombasa] ,” Kenya.

This species is monotypic.

Distribution. S coastal Kenya, from Tana River S to near Mombasa.

Descriptive notes. Head-body 218-304 mm, tail 213-270 mm, ear 30-38 mm, hindfoot 68-79 mm; weight 410-690 g. There is no evidence of sexual dimorphism in body size. Tail of the Goldenrumped Sengi is ¢.85% of head-body length and is proximally thick and distally tapered; it has short and sparse hair with black skin on dorsal side and paler skin below. Distal tail has irregular subterminal white band. Dorsum is rufous, with red-brown tones. Hair on rump is diagnostically bright yellow; hair on head is brown with yellow tones. Venter is rufous. Pinnae are hairless, with black skin. Some individuals have indistinct dark central strips at anterior edge of yellow rump patch. Skin of rump is relatively thick and thicker on males than females. Snout is long and flexible. Dental formula is 1 0-1/3, C 1/1, P 4/4, M 2/2 (x2) = 34-36. Upper canines are relatively large, and males have longer upper canines than females. Presence of diminutive upper incisoris variable. Palatal foramina are absent. Postorbital processes are present. Females have two posterior, two intermediate, and no anterior nipples; males have no nipples. Four digits are present on each manus and pes; pollex and hallux are absent. Fifth manual digit is relatively short and has only two phalanges. Post-anal gland is well developed, and pectoral gland is absent. Karyotype is unknown.

Habitat. Semideciduous forests, woodlands, coral rag scrub, and fallow overgrown agricultural areas (closed canopies and dense leaflitter always present).

Food and Feeding. Diet of the Golden-rumped Sengi is strictly composed of invertebrates, mostly arthropods. Principal prey (in decreasing order of importance) includes beetles, centipedes, termites, crickets, ants, spiders, and earthworms.

Breeding. Golden-rumped Sengis are monogamous, and pairs mate for life. Breeding occurs year-round. Gestation is ¢.42 days, interbirth interval is ¢.82 days, and litters have 1-2 young. Weight at birth is ¢.80 g. Newborns are semi-precocial, remain in a nest for c.2 weeks, and are then weangd.

Activity patterns. Golden-rumped Sengis are fully terrestrial and exclusively diurnal. They emerge from nests just before dawn and return just before sunset. Nests are built from leaflitter piled on excavated depressions.

Movements, Home range and Social organization. Monogamous pairs of Goldenrumped Sengis share a defended home range, which generally does not overlap with neighboring pairs. Nevertheless, pair bonds are weak. Each member of a male-female pair nests separately and most of their time is spent independently. Both sexes mark their territory with scent glands. Territory size is up to 5 ha.

Status and Conservation. Classified as Endangered on The IUCN Red List. All known localities of Golden-rumped Sengis occur in less than 5000 km?*, and habitats are severely fragmented. Extent of habitat and number of mature individuals were last assessed in continuing decline. The most important site for the Golden-rumped Sengi is Arabuko-Sokoke Forest Reserve near the coast of Kenya that provides 372 km* of habitat. Population estimates for Arabuko-Sokoke decreased by about 30% between 1993 and 1996 and dropped another 9% to less than 13,000 individuals by 2008. No population surveys have been done since 2008. All other localities of occurrence are within 100 km of Arabuko-Sokoke and support much smaller populations. Within Arabuko-Sokoke, logging is a major threat that reduces canopy cover and density of leaflitter. Outside Arabuko-Sokoke, clearing of scrub and woodland,fire, and agricultural encroachment are principal threats. Subsistence hunting of the Golden-rumped Sengi was documented in the 1990s, with an estimated 3000 individuals harvested per year in Arabuko-Sokoke. Given the increase in human population in coastal Kenya, hunting pressure might be increasing.

Bibliography. Carlen et al. (2017), Corbet & Hanks (1968), Evans (1942), FitzGibbon (1994, 1995), FitzGibbon & Rathbun (1994, 2015), Olbricht & Stanley (2009), Rathbun (1979a, 1979b, 2009, 2013d), Rovero et al. (2008).

Figures

1. Golden-rumped Seng (Rhynchocyon chrysopygus), 2. Chequered Sengi (Rhynchocyon cirne), 3. White-tailed Sengi (Rhynchocyon stuhlmanni), 4. Black-and-rufous Sengi (Rhynchocyon petersi), 5. Gray-faced Sengi (Rhynchocyon udzungwensis), 6. Namib Round-eared Sengi (Macroscelides flavicaudatus), 7. Karoo Round-eared Sengi (Macroscelides proboscideus), 8. Etendeka Round-eared Sengi (Macroscelides micus), 9. Four-toed Sengi (Petrodromus tetradactylus), 10. North African Sengi (Petrosaltator rozeti), 11. Rufous Sengi (Elephantulus rufescens), 12. Somali Sengi (Elephantulus revoulii), 13. Dusky-footed Sengi (Elephantulus fuscipes), 14. Short-snouted Sengi (Elephantulus brachyrhynchus), 15. Dusky Sengi (Elephantulus fuscus), 16. Bushveld Sengi (Elephantulus intufi), 17. Western Rock Sengi (Elephantulus rupestris), 18. Eastern Rock Sengi (Elephantulus mywrus), 19. Cape Rock Sengi (Elephantulus edwardii), 20. Karoo Rock Sengi (Elephantulus pilicaudus)

Distribution. S coastal Kenya, from Tana River S to near Mombasa.