Petrodromus tetradactylus, Peters, 1846

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 : 230

9.

Four-toed Sengi

Petrodromus tetradactylus

French: Sengi a quatre doigts / German: Risselratte / Spanish: Sengi de cuatro dedos

Other common names: Fourtoed Elephant-shrew

Taxonomy. Petrodromus tetradactylus Peters, 1846 ,

Tette , Mozambique.

Ten subspecies are recognized.

Subspecies and Distribution.

P.t.tetradactylusPeters,1846—Rwanda,W&CTanzania,ECAngola,SEDRCongo,Zambia,Malawi,NZimbabwe,andNW&WCMozambique;perhapsBurundi.

P.t.beiraeRoberts,1913—CMozambique(SofZambeziRiver).

P.t.rooumaeThomas,1897—ETanzaniaandNMozambique.

P.t.sangiHeller,1912—SEKenya(TaitaHills).

P.t.schwanniThomas&Wroughton,1907—coastalSMozambique.

P.t.sultaniThomas,1897—coastalKenyaandNETanzania.

P.t.swynnertoniThomas,1918—EZimbabwe(ChimanimaniMts);specimensfromNELimpopoProvince,SouthAfrica,mightbethissubspecies.

P.t.torday:Thomas,1910—C&WDRCongoandextremeNEAngola.

P.t.warren:Thomas,1918—SMozambiqueandNESouthAfrica(NKwaZulu-NatalProvince).

P.t. zanzibaricus Corbet & Neal, 1965 — Unguja and Mafia Is (Zanzibar Archipelago), off Tanzania.

Descriptive notes. Head-body 163-210 mm, tail 156-187 mm, ear 34-39 mm, hindfoot 51-58 mm; weight 120-250 g. Female Four-toed Sengis can be slightly larger than males, but there is no substantial sexual dimorphism in body size. Tail is ¢.85% of head-body length, pinnae are broad and upright, and snout is long, thin, and flexible. Forelimb is long compared with other species of sengis, with hindlimb-to-forelimb ratio of 1-3 (greater or equal to 1-5 for other species). Pectoral gland is slightly developed, and subcaudal gland is absent. Furis soft and dense. Variable color patterns are associated with forms in different geographical areas. Dorsum can be dark brown, gray, buff-gray, and rust. Some forms have dark stripe along mid-dorsal axis of back. Lateral pelage tones can be buff, orange, or pale gray. Venter is off-white. Distinctive white eye-ring is present, with post-ocular patch of brown-black hair that intrudes on eye-ring and extends posteriorly to near base of ear. Hairless patch occurs on dorsal rump, just anterior to base oftail. Tail hair is sparse, and tail skin is black above and paler below. Tail lacks a tuft. In all but a few subspecies (e.g. beirae and warreni), there are 1-7mm bristles on ventral side of tail. Terminal shape of bristles can be knobbed, clubbed, or unexpanded. Base of each bristle is associated with sebaceous and tubular sweat glands. Females and males have two anterior, two intermediate, and no posterior nipples; male nipples are present but size is reduced. Five manual and four pedal digits are present; hallucal digits are absent. Dental formula is 3/3, C 1/1, P 4/4, M 2/2 (x2) = 40. Canine sizes are subequal to adjacent teeth. Number of palatal foramina is variable but reduced compared with other species of soft-furred sengis. Postorbital processes are absent. Karyotype is 2n = 28.

Habitat. Mesic regions with closed canopies and scrublands, woodlands, and forests with dense thickets and woody undergrowth. In more arid regions, habitats of the Four-toed Sengi include rocky outcrops and coastal and riparian areas. Leaf litteris common. Sheltering occurs in dense undergrowth and thickets. Pursuit elicits retreat into hollow tree trunks or under logs.

Food and Feeding. Arthropods, mainly insects, are the principal diet of the Four-toed Sengi. In coastal Kenya, invertebrate prey (in decreasing order of importance) includes

beetles, termites, centipedes, ants, crickets, millipedes, and spiders. Plant material can be a small proportion of the diet. In other regions, ants and termites are primary prey, supplemented with some plant matter and small proportions of seeds and fruits.

Breeding. The Four-toed Sengi is probably monogamous. Breeding periods vary by region and climate. Births in eastern Africa occur nearly year-round, but in southern Africa, they are mainly during wet season (August—October). Litters usually have one young, sometimes two. Birth weight is ¢.20-30 g, and newborns are highly precocial. No species of soft-furred sengis use nests to shelter or for rearing their young.

Activity patterns. Four-toed Sengis are fully terrestrial and mainly crepuscular, with some nocturnal activity and limited midday activity.

Movements, Home range and Social organization. Males and females form monogamous pairs; their home ranges overlap, but individuals spend most of their time alone. Combined home ranges of a pair does not overlap with home ranges of neighboring pairs. Territorial boundaries are defended. Social monogamy is probably a mateguarding strategy. In Arabuko-Sokoke Forest, Kenya, and in Tembe Elephant Park, South Africa, average home rangeis c.1-2 ha. Trail systems are actively built and maintained by sweeping aside debris with forelimbs.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Population trend of the Four-toed Sengi is unknown.

Bibliography. Ansell & Ansell (1969), Corbet (1974), Corbet & Hanks (1968), Dumbacher et al. (2016), Evans (1942), FitzGibbon (1995), Jennings & Rathbun (2001), Kingdon (1974a), Olbricht & Stanley (2009), Oxenham & Perrin (2009), Rathbun (1979b, 2009, 2013b), Rathbun & FitzGibbon (2015), Tripp (1971, 1972).

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)

Subspecies and Distribution. P.t.tetradactylusPeters,1846—Rwanda,W&CTanzania,ECAngola,SEDRCongo,Zambia,Malawi,NZimbabwe,andNW&WCMozambique;perhapsBurundi. P.t.beiraeRoberts,1913—CMozambique(SofZambeziRiver). P.t.rooumaeThomas,1897—ETanzaniaandNMozambique. P.t.sangiHeller,1912—SEKenya(TaitaHills). P.t.schwanniThomas&Wroughton,1907—coastalSMozambique. P.t.sultaniThomas,1897—coastalKenyaandNETanzania. P.t.swynnertoniThomas,1918—EZimbabwe(ChimanimaniMts);specimensfromNELimpopoProvince,SouthAfrica,mightbethissubspecies. P.t.torday:Thomas,1910—C&WDRCongoandextremeNEAngola. P.t.warren:Thomas,1918—SMozambiqueandNESouthAfrica(NKwaZulu-NatalProvince). P.t. zanzibaricus Corbet & Neal, 1965 — Unguja and Mafia Is (Zanzibar Archipelago), off Tanzania.