Amblysomus hottentotus (A. Smith, 1829)

Russell A. Mittermeier & Don E. Wilson, 2018, Chrysochloridae, Handbook of the Mammals of the World – Volume 8 Insectivores, Sloths and Colugos, Barcelona: Lynx Edicions, pp. 180-203 : 195

1.

Hottentot Golden Mole

Amblysomus hottentotus

French: Taupe-dorée hottentote / German: Hottentotten-Goldmull / Spanish: Topo dorado de los Hotentotes

Other common names: Zulu Golden Mole; Drakensberg Golden Mole (longiceps), Meester’s Golden Mole (meester)

Taxonomy. Chrysochloris hottentotus [sic] A. Smith, 1829, “interior parts of South Africa” (= Grahamstown, Eastern Cape, South Africa).

Amblysomus hottentotus 1s synonymous with A. ins, described by O. Thomas and H. Schwann in 1905. Traditionally, A. Aottentotus has included populations that are here considered distinct species: A. corriae , A. marleyi , A. robustus , and A. septentrionalis . Five subspecies recognized.

Subspecies and Distribution.

A.h.hottentotusA.Smith,1829—coastalpartsofEasternCapeProvince,SESouthAfrica,fromvicinityofVanStadensRivermouthEtoKingWilliam’sTownandEastLondon.

A.h.irisThomas&Schwann,1905—NcoastalpartsofKwaZulu-NatalProvince,ESouthAfrica,fromStLuciaStoRichard’sBay.

A.h.longicepsBroom,1907—DrakensbergescarpmentofKwaZulu-NatalandEasternCapeprovinces,ESouthAfrica,withmarginalintrusionintoFreeStateandMpumalangaprovincesandLesotho.

A.h.meester:Bronner,2000—NESouthAfrica,MpumalangaProvince,knownonlyfromNDrakensbergescarpmentaroundMariepskopandGraskop,rangingStovicinityofWhiteRiver,whereasinglespecimenhasbeencollected.

A. h. pondoliae Thomas & Schwann, 1905 — coastal parts of KwaZulu-Natal Province, E South Africa, between Durban and Port Edward.

Descriptive notes. Head-body 114-135 mm (males) and 104-135 mm (females), hindfoot 13-19 mm (males) and 12-18 mm (females) for the nominotypical Aottentotus; head—body 113-125 mm (males) and 104-132 mm (females), hindfoot 12-16 mm (males) and 11-16 mm (females) for subspecies iris; head—body 120-141 mm (males) and 119-139 mm (females), hindfoot 14-18 mm (males) and 13-18 mm (females) for subspecies longiceps; head-body 107-145 mm, hindfoot 14-17 mm for subspecies meesteri; head—body 107-145 mm (males) and 105-135 mm (females), hindfoot 12-18 mm (males) and 11-18 mm (females) for subspecies pondoliae; weight 37-85 g (males) and 37-60 g (females). The Hottentot Golden Mole is medium-sized, with considerable variation in size and pelage color among subspecies and populations. Generally, dorsum is rich dark reddish brown, becoming lighter reddish brown on flanks, with iridescent sheen of bronze, green, purple, or a mix. Venter is light grayish brown, with orange or reddish tinge, that is highly variable within populations, and sometimes with dark brown or pale whitish mid-ventral line from throat to belly. Muzzle is paler than dorsum, with off-white patches on cheeks, over subdermal eyes, and tiny ear openings. Albinistic specimens have creamy-beige to pale yellow (rarely recorded) dorsal and ventral pelage. Skull is elongated, zygomatic arches lack broad plates sweeping backward, mallei of inner ears are relatively small and unspecialized, and bullae are not externally evident. M? are usually absent, but when present, (less than 2% of individuals), they are small and range from triconid (molariform) to peg-like. Molar talonids are well developed except in subspecies meesteri, and P1 are sectorial (bicuspid) rather than molariform (tricuspid), except in subspecies meesteri, in which P1 tend to be more molariform. Dentition varies randomly and might reflect irregular sequence of tooth replacement in chrysochlorids. Foreclaws are moderately developed, claw on third digit is largest, second digit is much shorter, first digit is about one-half as long as second digit, and fourth digit is vestigial, with knob-like claw. Chromosomal complement has 2n = 30 and FN = 56.

Habitat. Wide variety of habitats from temperate grasslands and woodland savannas to Afro-montane forests, marshes, and coastal dunes, predominantly in mesic eastern regions of South Africa at elevations of ¢.0-2000 m. The Hottentot Golden Mole occurs mainly in Grassland and Savanna biomes, with marginal intrusion into Fynbos and Nama Karoo biomes in its southern distribution. It is particularly abundant in moist soils near water sources but also occurs far from surface water if soilis friable enough for burrowing and invertebrate prey is abundant. The Hottentot Golden Mole generally occurs in regions with mean annual rainfall more than 500 mm. It is frequently associated with agricultural land, golf courses, and gardens but less common in exotic plantations.

Food and Feeding. The Hottentot Golden Mole is insectivorous, mainly feeding on subterranean invertebrates such as earthworms and insects. In captivity, they will eat snails and plant material (e.g. potatoes and bulbs), although their digestive tracts are not specialized for herbivory. In nature, more than 97% of diets contain only earthworms, and less than 3% contain variety of insect prey including carabid beetle larvae, slugs, snails, crickets, insect pupae, and spiders. Individuals can consume up to 90% of their body weight daily. Although they will drink water in captivity, they probably obtain their moisture requirements from food and dew in the wild.

Breeding. Hottentot Golden Moles breed aseasonally, with peak reproductive activity in wet summer months. Females are polyestrous, with postpartum estrus, and male spermatogenesis is continuous, reflecting relatively constant microclimate of their subterranean niche. Litters have 1-3 young, but in most cases, females will carry one fetus in each uterine horn, giving rise to litters of two young. At birth, young are altricial, pale pink, and naked, except for a few hairs on foreheads and sides of muzzles. Ear openings are marked by small protuberances on sides of the head. Claws are well developed but soft. Neonates are ¢.47 mm long, weigh 4-5 g, and develop short dark brown dorsal pelage by juvenile size at 72 mm long and 17 g; ventral surfaces remain naked; and teeth are unerupted. Pale ventral pelage first appears at the late juvenile size at 80 mm long and ¢.27 g, and eviction from maternal burrows occurs at ¢.35—40 g.

Activity patterns. Hottentot Golden Moles live almost exclusively underground, constructing superficial burrows for foraging and deeper permanent burrows for residence. Subsurface tunnels are ¢.3 cm deep and 4-6 cm in diameter. Residential burrows can penetrate as far as 1 m belowground and are relatively complex in form, comprising grassor leaf-lined spherical nesting chambers 10-50 cm deep and 15-20 cm in diameter, other chambers used as latrines, and deeper (29-94 cm deep) spiraling bolt holes. In friable soils, horny nose pads are predominantly used for digging subsurface tunnels, and foreclaws assist with digging deeper tunnels and foraging in heavier soils. Hottentot Golden Moles are estimated to burrow at rates of up to 1-1-5 m/h and up to 9 m daily. Foraging burrows are generally 9.5-240 m long and might be extended by 4-12 m/day, depending on friability of soil and abundance of prey. Excavated soil from deep burrows is pushed up to the surface as molehills or compacted into tunnel walls; superficial foraging burrows result in ridges on the surface. Hottentot Golden Moles are highly sensitive to disturbances and will retreat quickly from superficial burrows to deeper burrows or bolt-holesif disturbed. They sometimes are attracted to the surface by movements of worms and insects, and they might even emerge and move on the surface, usually only at night and when food is scarce. At these times, they can be vulnerable to predation by owls and other predators. Hottentot Golden Moles are significantly less active in winter than summer, burrowing deeper and often entering torpor during colder winter months. They are particularly active after rain, and daily activity tends to peak at sunrise, sunset, and midnight, with periods of activity of up to two hours and periods of inactivity of 3-5 hours. During heavy rainfall events, underground burrows can become flooded. Hottentot Golden Moles cope with these situations by swimming; they can maintain a certain degree of buoyancy due to a layer of air retained in their wet fur. Soil temperatures in burrow systems are 0-8-32°C, but optimal thermal conditions for activity are 23-33°C, corresponding with their thermoneutral zone. Ambient temperatures below 15°C or higher than 30°C lead to torpor, characterized by reduced metabolic rate and considerable energetic saving.

Movements, Home range and Social organization. Hottentot Golden Moles are solitary and territorial. They actively defend their burrow systems, fighting aggressively with individuals of either sex by wrestling their opponent using foreclaws and biting opponent’s abdomen. Fighting is often accompanied by highpitched squeaks. Home range overlap is tolerated to some degree, and dominant individuals sometimes invade neighboring burrow systems to increase their home range size. Courtship involves chirruping vocalizations, head bobbing and foot stamping by the male, and rasping and squealing vocalizations by the female. Although solitary, the Hottentot Golden Mole has been recorded in sympatry with Common Mole-rats (Cryptomys hottentotus ), even to the point of sharing burrow systems. Densities of Hottentot Golden Moles up to 25 ind/ha have been recorded in prime habitat.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Nevertheless, distinct isolated evolutionary lineages with limited ranges or small population sizes might be under threat due to habitat alteration and degradation resulting from coastal urban development.

Bibliography. Bernard et al. (1994), Bronner (1995a, 1996, 2000, 2013b), Bronner & Mynhardt (2015b), Broom (1907 1908), Gilbert et al. (2008), Hickman (1986), Kuyper (1985), McConnell (1986), Mynhardt et al. (2015), Schoeman et al. (2004), Skinner & Chimimba (2005), Thomas & Schwann (1905).

Figures

0. Yellow Golden Mole (Calcochloris obtusirostris), 1. Hottentot Golden Mole (Amblysomus hottentotus), 2. Robust Golden Mole (Amblysomus robustus), 3. Highveld Golden Mole (Amblysomus septentrionalis), 4. Marley’s Golden Mole (Amblysomus marleyi), 5. Fynbos Golden Mole (Amblysomus corriae), 7. Congo Golden Mole (Huetia leucorhina), 8. Somali Golden Mole (Huetia tytonis), 9. Gunning’s Golden Mole (Neamblysomus gunningi), 10. Juliana’s Golden Mole (Neamblysomus julianae), 11. Arend’s Golden Mole (Carpitalpa arendsi), 12. Sclater’s Golden Mole (Chlorotalpa sclateri), 13. Duthie’s Golden Mole (Chlorotalpa duthieae), 14. Stuhlmann’s Golden Mole (Chrysochloris stuhlmanni), 15. Cape Golden Mole (Chrysochloris asiatica), 16. Visagie’s Golden Mole (Chrysochloris visagier), 17. Rough-haired Golden Mole (Chrysospalax villosa), 18. Giant Golden Mole (Chrysospalax trevelyani), 19. De Winton’s Golden Mole (Cryptochloris wintoni), 20. Van Zyl's Golden Mole (Cryptochloris zyli), 21. Grant's Golden Mole (Eremitalpa grant)

Subspecies and Distribution. A.h.hottentotusA.Smith,1829—coastalpartsofEasternCapeProvince,SESouthAfrica,fromvicinityofVanStadensRivermouthEtoKingWilliam’sTownandEastLondon. A.h.irisThomas&Schwann,1905—NcoastalpartsofKwaZulu-NatalProvince,ESouthAfrica,fromStLuciaStoRichard’sBay. A.h.longicepsBroom,1907—DrakensbergescarpmentofKwaZulu-NatalandEasternCapeprovinces,ESouthAfrica,withmarginalintrusionintoFreeStateandMpumalangaprovincesandLesotho. A.h.meester:Bronner,2000—NESouthAfrica,MpumalangaProvince,knownonlyfromNDrakensbergescarpmentaroundMariepskopandGraskop,rangingStovicinityofWhiteRiver,whereasinglespecimenhasbeencollected. A. h. pondoliae Thomas & Schwann, 1905 — coastal parts of KwaZulu-Natal Province, E South Africa, between Durban and Port Edward.