Arctonyx collaris, F. CUVIER, 1825

Helgen, Kristofer M., Lim, Norman T-L. & Helgen, Lauren E., 2008, The hog-badger is not an edentate: systematics and evolution of the genus Arctonyx (Mammalia: Mustelidae), Zoological Journal of the Linnean Society 154 (2), pp. 353-385 : 368-371

ARCTONYX COLLARIS F. CUVIER, 1825

Taxonomic synonymy (unique names as originally proposed): Arctonyx collaris F. Cuvier , in Geoffroy and G. Cuvier, 1825.

Arctonyx dictator Thomas, 1910 .

Arctonyx annaeus Thomas, 1921 .

(?) Arctonyx rostratus Matthew and Granger, 1923 .

Arctonyx collaris consul Pocock, 1940 .

A. c. nemaeus Pocock, 1941. (nomen nudum; lapsus for annaeus Thomas, 1921 )

Type material and type localities: The original description of collaris was based on a figure drawn by Alfred Duvaucel of two animals (cf. Fig. 7 , a composite impression that appeared in the original description) captured from hill country between Bhutan and India and exhibited in a menagerie at Barrackpore, West Bengal (Cuvier (in Geoffroy & Cuvier), 1825; Pocock, 1940, 1941). As noted above, the neotype of A collaris is AMNH 171170, an old adult male, skin and skull, from Nongpoh (25°54′N, 91°53′E), Khasi Hills (Meghalaya State, India). The holotype of dictator is BMNH 1910.10.1.31, an old adult female, skin and skull, from ‘Lam-ra, Trang, Northern Malay Peninsula [= peninsular Thailand]’. The holotype of annaeus is BMNH 1910.3.10.4, an immature male, skin and skull, from ‘Nha-trang’, Annam. The holotype of rostratus is no. 18393 in the AMNH Vertebrate Paleontology collection, from ‘Yenching-kao in the vicinity of Wan-hsien’, Sichuan (middle Pleistocene). The holotype of consul is BM (NH) 1938.10.10.2, skin and skull of an adult male, from ‘Thaundaung, near [Mt] Toungoo, 4500 feet’, Myanmar ( Pocock, 1940, 1941).

Common name: We suggest the common name ‘greater hog-badger’ for this species.

Diagnosis: The most obvious distinguishing feature of Arctonyx collaris is its massive size; condylobasal length measures ± 151 mm in adults (against ³ 149 mm in A. albogularis and <130 mm in A. hoevenii ). Indeed, A. collaris is the largest extant badger; in no other modern badger does condylobasal length exceed 150 mm. Thomas (1910: 425) aptly portrayed its tremendous size in his description of Arctonyx dictator , in which he wrote that ‘the chief feature about this Arctonyx is its enormous size, as the specimen looks like a small bear, and, though a female, exceeds any example, male or female, of A. collaris [i.e. A. albogularis ] in the [ BMNH] collection.’ Cuvier (in Geoffroy & Cuvier, 1825) was likewise impressed with its robustness, erecting the generic name Arctonyx (meaning ‘bear-claw’) based upon this species ( Palmer, 1904).

Arctonyx collaris has a massive, robustly constructed skull featuring a relatively high-domed braincase and pronounced sagittal crest, and usually a marked diastema between P2 and P 3 in both the upper and the lower jaws ( Figs 2–6 , Tables 1–3). Although remarkably variable in size and shape (see below), the cheekteeth are on average considerably larger than in A. albogularis or A. hoevenii ( Fig. 3 ; Tables 1–3).

Although details of the head-striping pattern and various aspects of pelage marking are individually variable ( Osgood, 1932; Pocock, 1941), in general the forequarters are blackish, while the mid-back, hindquarters and tail are white or heavily grizzled with white, which renders the pelage typically paler than in the other Arctonyx species ( Figs 7 , 9 ). The pelage is characteristically shorter and coarser than in other Arctonyx . The long guard hairs of the winter coat (outer hairs measuring ³ 80 mm) overlap in length with but tend to be considerably shorter than these hairs in Arctonyx albogularis (outer hairs ± 70 mm), and the winter underfur is always much less dense than in A. albogularis . Arctonyx collaris also has a proportionally longer tail than A. albogularis or A. hoevenii , and longer and more massive claws than congeners, particularly on the forelimbs.

Distribution: Arctonyx collaris is distributed throughout the far eastern portion of the Indian Subcontinent, extending south throughout Indochina to peninsular Myanmar and Thailand ( Fig. 11 ). Records from the subcontinent are from Nagaland (Naga Hills; BMNH), Meghalaya (Khasi and Jaintia Hills; AMNH, BMNH), ‘Bengal’ ( BMNH; probably ‘some locality to the east of the Ganges and Brahmaputra, possibly from Chittagong’: Pocock, 1941), Bangladesh (‘ Chittagong Hills’, BMNH; Pocock, 1941), and probably from Manipur (see Rakamantha, 1994). Arctonyx albogularis also occurs in the Indian subcontinent portion of this range. As noted above, recently published reports of Arctonyx from the Indian states of Assam ( Choudhury, 1997a), Arunachal Pradesh ( Choudhury, 1997b), North [West] Bengal ( Choudhury, 1999) and Nagaland ( Choudhury, 2000), and from extreme northern Myanmar ( Rao et al., 2005) have not been identified to species, and could represent A. albogularis , A. collaris or both species in co-occurrence (cf. Rakamantha, 1994).

All Arctonyx specimens that we have examined from Myanmar (BMNH, MCZ, USNM), Thailand (AMNH, BMNH, MCZ, USNM), Vietnam (BMNH, MNHN), Cambodia (MNHN) and Laos (AMNH, ANSP, FMNH) represent A collaris (for most or all distributional records and sources and associated discussion see Thomas, 1910, 1921; Osgood, 1932; Allen & Coolidge, 1940; Pocock, 1940, 1941; Urbain & Friant, 1940; van Tien, 1966; Van Peenen, 1969; Deuve, 1972; Rabinowitz, 1990; Rabinowitz & Walker, 1991; Rozhnov, 1994a, 1994b; Bergmans, 1995; Duckworth, 1997, 1998; Duckworth, Salter & Khounboline, 1999).

The southernmost distributional extent of A. collaris lies in the far north of the Malay Peninsula, in peninsular Thailand. There is an unverified record from the Malaysian state of Upper Perak ( Tate, 1947; Medway, 1978), but no vouchered specimens originate from Malaysia and it appears to be absent from most (if not all) of that country. The westernmost occurrence of A. collaris is probably defined by the Brahmaptura and Ganges drainages (see above). The exact northern boundary of occurrence of A. collaris remains to be established, but may lie in Yunnan. Apart from two skins from Lichiang, Yunnan, which we provisionally identify as A. collaris (see above, under A. albogularis ), all specimens from China that we have seen (AMNH, FMNH, MCZ, MNHN, USNM) represent A. albogularis . The absolute, striking distinctions in size, pelage and qualitative cranial morphology between available adult samples of A. albogularis and A. collaris indicate no intergradation between these taxa (cf. Pocock, 1941).

Most museum records of A. collaris from India and Myanmar with associated elevational data derive from between 700 and 1500 m (BMNH). Similarly, most museum specimens from Thailand, Vietnam and Laos with associated elevational data derive from localities situated between 600 and 1300 m. There are only a handful of specimens of A. collaris in museums marked with elevations below 600 m; the lowest elevation given on a specimen label is ‘100 m’ (BMNH 15.12.1.8, Sai Yoke, Thailand). Duckworth (1997) noted that ‘all recent records [of Arctonyx in Laos] came from above 500 m, but as all were in the same catchment, it is unclear if this represents a pattern of altitude, geography, or even just chance... All records were from forest, and elsewhere it occurs mainly in forest’ (see also Duckworth, 1998; Duckworth et al., 1999). Long & Minh (2006) discussed recent records of A. collaris in central Vietnam (the Central Annamites area), where it was encountered in ‘primary lower montane forest’ at 900 m at one site, and in ‘disturbed, primary hill forest’ at 640 m at another. Based on our canvas of published accounts and specimen label data, we suggest that the seemingly patchy occurrence of A. collaris in Southeast Asia ( Duckworth et al., 1999; Long & Minh, 2006) reflects its typical absence from lower-elevation habitats and preferred occurrence in little-disturbed hill and lower montane forests above about 500– 600 m. Undisturbed upland forested tracts possibly offer the best combination of sites for burrowing, diversity of food and escape from predation for A. collaris . The core elevational range of this species appears to lie between about 600 and 1400 m, with all records spanning 100–1500 m, but little information is available with respect to its upper elevational limit of occurrence. In their account of the mammals of Thailand, Lekagul & McNeely (1977) quoted the upper limit of occurrence as 3500 m for ‘ A. collaris ’, but we suspect this elevational information is based on highelevation localities quoted for the genus in China or Sumatra, where species other than A. collaris are found.

Geographical variation: Aspects of geographical variation in A. collaris have been discussed by Thomas (1921), Osgood (1932), Pocock (1940, 1941); Urbain & Friant (1940) and Lekagul & McNeely (1977), but always on the basis of little comparative material, in particular with very few adult skulls available. One notion that has been presented by previous reviewers is that Indochinese Arctonyx are smaller at more northern latitudes than in the south ( Pocock, 1941; Lekagul & McNeely, 1977), although Osgood (1932) observed that ‘specimens from southern Laos are fully as large as northern ones.’ Our larger sample of specimens from the region offers little evidence for a latitudinal size gradient. In any case, many fewer full-grown skulls are available from northern Myanmar and Thailand (e.g. BMNH, MCZ, USNM) than from more southerly localities, and many skulls are too imprecisely localized (e.g. skulls labelled ‘Siam’, ‘Vietnam’, or unlabelled from Indochina at MNHN and BMNH) to be useful in assessing geographical variation. We agree with Osgood (1932) that there is no clear basis for the subspecific discrimination of the nominal taxon annaeus , named by Thomas (1921) on the basis of an immature specimen, from ‘ A. c. dictator ’ (which we do not distinguish subspecifically from typical A. collaris ). Pocock’s (1940) description of consul as a somewhat smaller race linking ‘ A. c. dictator ’ (i.e. A. collaris ) and ‘ A. c. taxoides ’ (i.e. A. albogularis ) was prematurely conceived, in part because the majority of his specimens were immature (and see Pocock, 1941: 499). Our study of nearly all available museum material of Arctonyx identifies A. collaris as a morphologically distinctive species with no evidence for morphological intermediacy linking it to either A. albogularis or A. hoevenii ( Figs 2 , 4–6 ), and identifies no clear basis as yet for characterizing geographical variation within A. collaris at the trinomial level.

The middle Pleistocene fossil badger Arctonyx rostratus Matthew & Granger, 1923 , originally described as late Pliocene in age (see Hooijer, 1947) from Sichuan Province in China (type locality ‘Yen-chingkao in the vicinity of Wan-hsien’), differs from the modern hog-badger of Sichuan (i.e. A. albogularis ) in its larger size, heavier molars, pronounced diastema between P2 and P3, and more parallel-sided rostrum. All of these are characteristic features of A. collaris . Pei (1940) discussed an additional record of ‘ Arctonyx cf. rostratus ’ from the Pleistocene of Jiangsu Province, further to the east. In the holotype of rostratus , condylobasal length measures 148 mm – i.e. closer to samples of modern A. albogularis (range 110– 149 mm) than A. collaris (150–172 mm), although falling close to both (in the type the zygomatic arches are broken and missing, such that the skull cannot be plotted in our Fig. 2 ). Based on its qualitative features, we suspect that rostratus is best characterized as a synonym (or perhaps chronological subspecies) of A. collaris . If this is the case, Sichuan and Jiangsu specimens referred to rostratus indicate that the geographical range of A. collaris extended further north in the middle Pleistocene than today. However, we suggest that it is inadvisable to synonymize this fossil taxon formally before its morphometric and qualitative features are more conclusively compared against both A. collaris and A. albogularis . More recently, Long, de Vos & Ciochon (1994) referred Middle–Late Pleistocene material of A. collaris from six different cave sites in Indochina and Thailand to ‘ A. cf. rostratus ’.

Pocock (1941) aptly illustrated the extreme variation in cheektooth size, shape and occlusal morphology within a local population of A. collaris from Mt Toungoo in Myanmar (e.g. Fig. 12 ). Similarly striking is the range of dental size variation seen locally on the Bolovens Plateau of Laos and in peninsular Thailand (e.g. Figs 12 , 13 ). Based on our museum studies of carnivores worldwide, we suspect that A. collaris shows more intrapopulational variation in molar size than any other carnivore species ( Pocock, 1940), although molar variability is also striking in local series of Arctonyx hoevenii . This is an excellent avenue for further, detailed comparative ecomorphological study. We suggest that extraordinary cheektooth variability in Arctonyx may be tied to the greater comparative importance of vermivory in its diet relative to other badgers (see below). Committed vermivory in mammals is commonly correlated with evolutionary reduction or loss of molars and/or unusual molar size and shape variability (e.g. Griffiths, 1978; Rickart, Heaney & Utzurrum, 1991; Balete et al., 2007), assumedly reflecting the reduced importance of stringent genetic control in molar development in mammalian vermivores. Vermivory (and myrmecophagy) are also usually accompanied by a comparative elongation of the rostrum relative to related taxa ( Anderson & Jones, 1967; Griffiths, 1978; Musser, 1982), as seen in Arctonyx relative to other badgers – assumedly an adaptation for digging through the soil with the snout.

Natural history: Arctonyx collaris is found only in Southeast Asia, where it predominantly occurs in little-disturbed hill and lower montane forests. Entirely terrestrial, it sleeps in ‘burrows they dig for themselves or in convenient natural shelters, like rock-crevices’ ( Pocock, 1941: 447). Pocock (1941: 447) characterized A. collaris as nocturnal, but Duckworth et al. (1999: 188) considered it to be diurnal. Like A. hoevenii of montane Sumatra (see below), A. collaris is probably instead best characterized as cathemeral (i.e. active sporadically in accordance with its needs, without being commitedly nocturnal or diurnal; e.g. Curtis & Rasmussen, 2006; Hill, 2006; Tattersall, 2006).

Arctonyx collaris apparently has poor eyesight, but is large, powerful and ferocious, and perhaps as a result it apparently is relatively unwary for a wild animal of its size ( Pocock, 1941). It can be approached closely and killed by men and dogs ( Pocock, 1941; Duckworth et al., 1999) or by large predators, such as cats. Rabinowitz (1990) and Rabinowitz & Walker (1991) found that A. collaris was a common animal in Huai Kha Khaeng Wildlife Sanctuary in Thailand, noting that ‘it was sighted on several occasions and its remains were frequently found in carnivore faeces’ ( Rabinowitz & Walker, 1991). Identifiable remains of Arctonyx were found in 5% of large carnivore scats found at one site in the sanctuary.

Very little is recorded of the diet of A. collaris . Most available information was summarized by Pocock (1941) in his account of ‘ Arctonyx collaris consul ’, but unfortunately this is based almost entirely on observations of animals in captivity. Observations of five animals are available ( Pocock, 1941: 447). Pocock (1941: 447) noted that the two animals on which Cuvier’s original description of A. collaris is based ‘would eat meat, but preferred fruit, bread and milk.’ An adult male A. collaris captured in Moulmein ( Myanmar) ‘ate voraciously meat, entrails, snakes and other reptiles, fish, and plantains, but was fondest of earthworms, which it greedily devoured as fast as they could be dug up.’ Another animal from Arakan ( Myanmar), not identified with respect to sex or age, ‘refused to eat meat or flesh of any kind, but would take bread and milk, and was particularly partial to plantains.’ A cub from Tura in the Garo Hills, first described by Jackson (1918) (which, however, may have been either A. albogularis or A. collaris ), fed on:

rice and rice-water, which it ate noisily, like a pig, holding the bowl between its paws. Later it had two large tins of earthworms daily, showing the same liking for them [as the Moulmein animal]... as well as bread and milk and pudding. It also ate centipedes and the contents presumably of reptiles’ eggs, rejecting the ‘leathery’ shells, but [unlike the Moulmein animal]... it was afraid of snakes and would not touch roots, fruits, or vegetables ( Pocock, 1941: 447).

In their book on Thai mammals, Lekagul & McNeely (1977) noted that Arctonyx feeds on ‘tubers, roots, earthworms, insects, and other small living creatures’, but the source of this information was not noted. Perhaps the best that can be said in summary is that A. collaris is omnivorous, and may at least partially specialize on eating earthworms.

Thomas (1910), quoting H. C. Robinson, noted that this species was known by the native name Sabima in peninsular Thailand in the early 20th century. Cuvier (in Geoffroy & Cuvier, 1825) gave the local name of this species as Bali-Saur or Bali-Soar in eastern India (apparently meaning ‘sand-pig’ or ‘bear-pig’ in Hindi). Pocock (1941: 427) provided a number of local names for Arctonyx in eastern India and Myanmar, but it is unclear whether these listed names reference A. collaris , A. albogularis or both species.

Figures

Figure 2. Comparative cranial size of Arctonyx taxa. Skull length (condylobasal length) versus width (zygomatic width) in 66 intact adult skulls (A. hoevenii of Sumatra, triangles; A. albogularis of China and India, diamonds; A. collaris of Indochina and eastern India, squares). Adults and old adults are denoted by solid shapes, young adults by open shapes. The clusters of adult and old adult skulls of Arctonyx collaris are widely separated from other Arctonyx taxa in this bivariate space, and do not overlap bivariately with A. hoevenii or A. albogularis even when young adults are included.

Figure 3. Comparative molar dimensions in Arctonyx skulls. Maximum crown length versus crown width for upper M1 (zygomatic width) in 80 intact molars, excluding excessively worn teeth (A. hoevenii, triangles; A. albogularis, diamonds; A. collaris, squares). All ages pooled. Whereas the size-variable teeth of A. collaris and A. albogularis overlap broadly in their dimensions, molar dimensions for Arctonyx hoevenii show no overlap with the other two species.

Figure 4. Ungrouped morphometric separation (principal components analysis) of specimens identified (on the basis of geography and qualitative features) as A. hoevenii, A. albogularis and A. collaris, drawing from ten craniodental measurements (Table 2). Symbols for taxa and ages as in Figure 3.

Figure 5. Grouped morphometric separation (discriminant function analysis) drawing from the same specimens and measurements for A. hoevenii, A. albogularis and A. collaris as in Figure 4 (Table 2). All ages (young adult, adult, old adult) pooled together; A. hoevenii, triangles; A. albogularis, diamonds; A collaris, squares.

Figure 6. Representative skulls of the three species of Arctonyx. A, Arctonyx hoevenii, USNM 269073, adult female from ‘Atjeh’, northern Sumatra. B, A. collaris, USNM 256678, adult female, from Trang, Peninsular Thailand (topotypical). C, A. albogularis, FMNH 39373, adult female, from Hsien, Fujian Province, China. Scale bar = 20 mm.

Figure 7. Plate depicting Arctonyx collaris, or the ‘Bali- Soar’, from the original description of the genus and species by Cuvier (in Geoffroy & Cuvier, 1825). Based in part on this plate, we regard Arctonyx collaris as the original name for the larger Arctonyx species of mainland Asia (see text).

Figure 9. Representative study skins of the three species of Arctonyx. A, Arctonyx albogularis, USNM 258533, adult male from ‘Wen-Chuan’, Sichuan, China. B, A. collaris, USNM 256678, adult female, from Trang, Peninsular Thailand (topotypical). C, A. hoevenii, ANSP 20232, young adult female from Gunung Leuser, northern Sumatra.

Figure 11. Map of the approximate distribution of Arctonyx spp. Verified point localities are figured for A. collaris (triangles) and A. hoevenii (circles). The approximate range of A. albogularis is shown by cross-hatching, mainly as documented by Pocock (1941), Zhang (1997) and the present study. We have not seen specimens of Arctonyx from far south-eastern China, and only questionably refer these populations to A. albogularis (cf. Zhang, 1997).

Figure 12. Local and regional variation in the larger cheekteeth (upper P4 and M1) of Arctonyx collaris, depicted to scale, as figured by Pocock (1941). A, adult male, eastern India (‘Bengal’). B, immature male, eastern India (Nagaland, Naga Hills). C, immature male, eastern India (Meghalaya, Jaintia Hills). D, immature male, Myanmar (Kindat area). E, old adult male, Myanmar (Mt Toungoo). F, immature female, Myanmar (Lockaw). G, immature male, Vietnam (Nhatrang). H, immature male, Myanmar (Mt Toungoo). I, immature female, Myanmar (Chin Hills). Labelled as by Pocock (1941). Based on vouchered specimens at BMNH (see Pocock, 1941).

Figure 13. Additional examples of variation in the larger cheekteeth (upper P4 and M1) of Arctonyx collaris, depicted photographically, to scale. Above, AMNH 87394, adult male, Laos (Bolovens Plateau); middle, AMNH 87395, young adult female, Laos (Bolovens Plateau); below, AMNH 37221, old adult, unsexed, Thailand (‘Siam’). Scale bar = 10 mm.