Pigs, Peccaries and Hippos Status Survey and Action Plan (1993)

 

Chapter 5

 

The Eurasian Suids

 

Sus and Babyrousa

 

 

5.1. Taxonomy and Description

 

Colin P. Groves and Peter Grubb

 

The Genus Sus

 

According to the major review of the genus Sus by Groves (1981) at least 5 species and 24 subspecies are recognized. A more recent study by Hardjasasmita (1987), is at variance with Groves' review, in that it recognizes several additional species and subspecies from Indonesia. However, as this author does not provide any new evidence to support his conclusions or to counter those of Groves' we do not see any need to modify the latter's treatment of the wild pigs of this country. Nevertheless, some important new evidence suggests that two additional species should be recognized from the Philippines (see below), making a total of 7 species and (approximately) 22 subspecies, as follows:

 

1.      The Eurasian Wild Pig, Sus scrofa (c. 17 ssp.).

2.      The Pigmy Hog, Sus salvanius (0 ssp.).

3.      The Javan Warty Pig, Sus verrucosus (2 ssp.).

4.      The Bearded Pig, Sus barbatus (3 ssp.).

5.      The Philippine Warty Pig, Sus philippensis (0? ssp.).

6.      The Visayan Warty Pig, Sus cebifrons (0? ssp.).

7.      The Sulawesi Warty Pig, Sus celebensis (0 ssp.).

 

Groves (1981) also drew attention to a 'mystery' pig, S. bucculentus, which is known from only two skulls from Cochin China (now extreme south Viet Nam), collected in the late 19th Century. This animal is evidently closely allied to S. verrucosus, but its external appearance and present status are entirely unknown.

 

The pigs of this genus may be separated into two groups, the non-warty pigs (2 spp.) and the warty pigs (5 or 6 spp.), these groups being differentiated by various cranial and dental characters and the development of conspicuous facial adornments or 'warts' in adult males of the warty pigs alone.

 

 

The Non-warty Pigs of the Genus Sus

 

The two species are sympatric, S. scrofa occurring over the entire known range of S. salvanius, namely the sub-Himalayan alluvial tract of the northern Indian sub-continent, so they must be specifically distinct. Moreover, S. salvanius has a number of highly distinctive characters (e.g. extreme reduction in body size, rudimentary tail and only three pairs of mammae), which serve to differentiate it from scrofa and, indeed, all other wild pigs. These characters have led some authors to annex the species as a separate genus or sub-genus, Porcula, though Groves considered it more closely allied to scrofa than to other members of the genus, and believed that most of the species' diagnostic features are correlated with the reduction in body size.

 

In both species the male's lower canine has the inferior surface narrower than the posterior surface. The female's canines are like small versions of the male's. The preorbital fossa is shallow with sloping borders.

 

 

1. The Eurasian Wild Pig (Sus scrofa)

 

A moderate to large sized pig with a relatively short muzzle and no face warts. Females 88.8-95.3% of males in condylobasal length in various populations; about 80% of male body weight. Relatively long-limbed, especially in northern races; medial false hooves as long as lateral; ears relatively large; tail relatively long, with simple tuft; head not large compared to body; snout disc perpendicular to axis of head; back rounded. No warts or gonial whorl. Often well-haired; hairs all agouti; general color brown with a tendency to blackish, grayish or rufous; face, cheeks and throat with a grizzling of whitish hairs or more strongly expressed markings; underside dark; bristles of nape long, in some races forming a distinct narrow nuchal crest or mane which extends down the back; under-fur thick and woolly or absent. Piglets longitudinally striped, stripes gradually fading after five to six months. Four to six pairs of mammae.

 

There is considerable variation in size, with sample-means for greatest length of skull in males ranging from 275 mm (Ryukyu Islands) to 466 mm (Ukraine). In general, insular pigs are smaller than those on the adjacent mainland, and southern pigs are smaller than northern ones. In Groves's (1981) revision of this species, no groupings of subspecies were recognized, but four regional groupings are used here in an informal sense in order to distinguish certain features amongst the 17 currently recognized subspecies (Fig. 10, section 5.2):

 

·        Western races. Mane poorly developed except in the nominate race and adjacent attila; under wool thick. Sample-means of greatest length of skull in males 308-466 mm. Mostly high-skulled races, though lybicus and some scrofa are low skulled. The following (6) subspecies are included:

 

S. s. scrofa (northern low-skulled and southern high-skulled populations may be subspecifically distinct): North Spain, North Italy, France, Germany, Benelux, Denmark, Poland, Czechoslovakia, Albania (?);

 

S. s. meridionalis: Andalusia; also Sardinia & Corsica (though the island populations are almost certainly feral, having arrived in the Holocene, probably as primitive domestic stock - see Vigne, 1988);

 

S. s. algira: Tunisia, Algeria, Morocco on the coastal side of the mountains;

 

S. s. attila: Hungary, Ukraine, Central Byelorussia east into Soviet Central Asia as far as the Aral Sea; south to the northern flank of the Caucasus and the Mesopotamian Delta, Iraq;

 

S. s. lybicus: Transcaucasia, Turkey, Levant, Palestine, Yugoslavia (also extinct in Nile Delta, though this was probably a feral population – see: Verpmann, 1987 - as there is no record of this species of the species in Egypt in any archeological sites of Noelithic, Bronze or Iron Age); and

 

S. s. nigripes: flanks of the Tienshan Range in Central Asia and (according to Russian authorities) ranging west to the Caspian Sea, south to northern Iran, Afghanistan, western and southern Mongolia and China, and east as far as Novosibirsk.

 

·        Indian races. Under wool sparse (davidi) or absent; mane long and thick; snout and mouth-gonion bands fairly well defined (davidi) or absent. Sample-means of greatest length of skull in males 365-490 mm (339 mm in Bopeta - see below). All are high-skulled races, except for davidi, which is low skulled. The (4) subspecies included are:

 

S. s. davidi: Pakistan and north-west India to south-eastern Iran;

 

S. s. cristatus: Sub-Himalayan region from Ludhiana, Punjab, through Nepal and Sikkim to Nagaland and North Burma; Uttar Pradesh; Madhya Pradesh; probably Kolhapur; Bihar; Bengal south through Burma and western Thailand to Isthmus of Kra;

 

S. s. affinis: southern India and most of Sri Lanka; and

 

S. s. subsp: Bopeta, Central Province, Sri Lanka (based on a single very small skull).

 

·        Eastern races. A definite whitish streak from angle of mouth to lower jaw; under wool thick except in moupinensis; mane poor or absent. Sample-means of greatest length of skull in males 327-474 mm (275 on Iriomote). Mostly high-skulled races, except for ussuricus. The (6) subspecies included are:

  

S. s. sibiricus: Mongolia, Transbaikalia;

 

S. s. ussuricus: Soviet Far East, Manchuria, Korea;

 

S. s. leucomystax: Honshu, Shikoku, Kyushu;

 

S. s. riukiuanus: Ryukyu Islands (including at least Ishigaki and Iriomote;

 

S. s. taivanus: Taiwan;

 

S. s. moupinensis: Coastal China south to Vietnam and west to Szechwan.

 

·        Indonesian race (or banded pig), S. s. vittatus. Body hair sparse, no under wool, mane fairly long, a broad reddish brown band along middle of muzzle, broadening at angles of mouth and on sides of upper lip, where it extends backwards to disappear on sides of neck Greatest length of skull in males, 284-380 mm in sample means. Range: Peninsular Malaysia; the offshore islands of Terutau and Langkawi; Sumatra; Riau Archipelago (includes Bulan, Jeri, Ungar Batam and Karimun); Java and offshore island Peucang; Bali; Lombok; Sumbawa; and Komodo.

 

 

2. The Pigmy Hog (Sus salvanius)

 

This is the smallest of the living suids, with greatest length of skull in males averaging only 179 mm; body weight is 6.6-9.7 kg in adults, head and body length 55-71 cm (mean, 58 cm) (Oliver 1980); female about 87% of male in condylobasal length. Relatively short-limbed; hind limbs long relative to forelimbs; medial false hooves relatively short; ears small; tail very short, barely tufted; head moderate in size; snout disc perpendicular to axis of head; back short, rounded. No warts or gonial whorl. Hairs all agouti-banded; little or no mane; underside wholly dark. Piglets faintly striped. Only three pairs of mammae. The pigmy hog is confined to the tall grass savannah or terai of the Himalayan foothills and now restricted to northern Assam (Oliver, 1980).

 

 

The Warty Pigs of the Genus Sus

 

The warty pigs have sometimes been referred to as the 'verrucosus group' distinct from the two, non-warty species (above), one of which (scrofa) is sympatric with verrucosus and barbatus over parts of their ranges. Hybridization between scrofa and all five species of warty pigs has been recorded, albeit in captivity in most instances. Since all of the warty pigs have parapatric distributions, they are considered conspecific by some authors and, unlike the non-warty Sus spp., their separation is based exclusively on morphological characters.

 

The 'warty pigs' are so-called because the adult males typically develop three pairs of warts, namely 'infraocular' (= infraorbital) warts on the cheek (malar) swellings; 'gonial' warts on the jaw angle; and 'preocular' (= preorbital) warts above the canine root flanges. The relative development of these warts, which continue to enlarge throughout life, are diagnostic for three 'Sundaic' species, the infraorbital warts being most developed in verrucosus and the preocular warts being most developed in celebensis. The facial warts are reduced in barbatus, in which the gonial warts are concealed by the growth of the cheek whiskers, the 'gonial whorl' or 'beard', and in the two eastern (Wallacian) Philippine species, philippensis and cebifrons. The warts may also be present, though very small, in females of these species. The structure of the canine is also characteristic of warty pigs, the inferior surface of the lower canine being broader than the posterior surface, so that a section of the tooth is more or less an equilateral triangle. The females have diminutive canines, which tend to point simply down (upper teeth) or up (lower). The preorbital fossa is always deeply excavated with over-hanging, shelf-like borders.

 

 

3. The Javan Warty Pig (S. verrucosus)

 

This species and the next are distinguished by the great elongation of the face. Size medium to large; sexual dimorphism in size greater than in other species; males very large - more than twice the weight of females; female condylobasal skull length 80.3 and 83.3% of male measurements in two populations; relatively long limbed; ears large; tail relatively long, tufted simply; head large, heavy compared to body; back long, straight; snout disc somewhat oblique to axis of head. Three pairs of warts; infraorbital pair largest; long tuft of hair on gonion marks spot where gonial wart will emerge late in life in males. Body hairs red to yellow with black tips, or pure black; a broad mane extending to rump; underside sharply marked off, yellowish. Piglets faintly striped, when very small only. Six pairs of mammae. Two subspecies are recognized, as follows:

 

S. v. verrucosus: Java and, formerly, Madura, where it is now extinct; and

 

S. v. blouchi: confined to Bawean

 

The nominate form is much larger, with sample-means of greatest skull length 408-429 mm in males; the recently described Bawean race (Groves, 1981) having a skull length of only 354 mm.

 

4. The Bearded Pig (S. barbatus)

 

S. barbatus is closely related to S. verrucosus, but is typically distinguished by the bushy gonial tuft of hair enlarged into a cheek-beard; much smaller warts; and often a still more elongated skull. Size medium to large; females relatively larger in relation to males, 88.2-93.6% of males in condylobasal skull length. Relatively long limbed; ears relatively small; tail long with large terminal tuft divided into distinct anterior and posterior parts; head large, heavy; snout disc quite oblique to axis of head; back straight, long. Two pairs of warts in males; whorl on gonion but no gonial wart; warts small or absent in females. Hairs agouti or uniform (black); broad long mane, extending to rump; underside wholly dark. Piglets striped, but pattern fading before six months. Six pairs of mammae. The three currently recognized subspecies, are:

 

oi: Peninsular (West) Malaysia, Sumatra, Bangka and Palau Bintang in the Riau Archipelago;

 

barbatus: Borneo and the westernmost of the Sulu Archipelago (Sibutu and Tawitawi); and

 

ahoenobarbus from Balabac, Palawan and offshore islands, and the Calamianes group.

 

The subspecies differ in size, coloration and hair development. The nominate race of Borneo is large, with a well-developed beard. S. b. oi is somewhat variable over its disjunct range, but is also very large, has coarse bushy hair over the top of the snout and a smaller beard. S. b. ahoenobarbus is much smaller and darker. Sample-means of greatest length of skull in males are 359-365 mm, against 435-505 mm in the larger races.

 

 

5. The Philippine Warty Pig (S. philippensis)

 

Following Sanborn (1952), the wild pigs of the main (Wallacian Region) Philippine archipelago (i.e. excluding the Palawan group of islands in the Sundaic Region) have generally been assigned to the species S. celebensis. However, Groves (1981) rejected this arrangement on finding that their cranial characters aligned them with S. barbatus and not S. celebensis - a view subsequently endorsed by Mudar (1986) - whilst acknowledging that they might merit separation as full species. Recently-photographed captive adult boars from Panay (S. 'barbatus' cebifrons) and from Luzon and Mindanao (S. 'barbatus' philippensis) are unlike S. barbatus and differ amongst themselves. Furthermore, skulls of S. 'b.' cebifrons from Negros in the central Philippine 'Visayas Region' recently examined by C. P. Groves show several differences from skulls of philippensis. This new information is yet to be fully reported but it has led to a reappraisal of the systematics of Philippine pigs. It now seems appropriate to recognize two separate species on the Philippines (excluding the Palawan Region), namely S. philippensis and S. cebifrons - a treatment that corresponds with the systematics of the Philippine deer (Grubb and Groves, 1983).

 

The Philippine warty pig, S. philippensis, occurs on most of the larger, outermost islands (Mindoro, Mainit, Luzon, Catanduanes, Samar, Leyte, Biliran, Mindanao, Basilan and Jolo) in the eastern Philippines. It is a black pig, sometimes with a pale snout-band and red-brown patches in the mane. It is smaller than S. barbatus ahoenobarbus but somewhat larger than S. cebifrons (means of greatest skull-length measurements are 318-335 mm in adult males). A boar from Luzon strongly resembles S. celebensis in the distinct crest and prominent preorbital warts, though these features are less strongly expressed in another male from Mindanao. This variation may reflect differences between island populations, a conclusion that is to be expected in view of faunal provincialism in the Philippines (Heaney, 1986). Therefore, it will be necessary to reconsider the systematics of the species, as it may prove to be polytypic.

 

 

6. The Visayan Warty Pig (S. cebifrons)

 

This is a smaller pig occurring allopatrically to S. philippensis on the west central islands of the Philippines. Skull length is 299 mm (mean of two males from Negros) and recently determined features of Negros skulls distinguish this species from S. philippensis as well as from other, better-known warty pigs. The external appearance is not well known but boars from Panay have a long mane extending to the rump and large facial warts, while skins from Negros have white hairs on the shoulders and sides. The species is reliably recorded from the Visayan Islands of Cebu, Siquijor, Guimaras, Negros and Panay - identified as the Negros Faunal Region by Heaney (1986). However, it is already extinct over the majority of its known, former range (see later text).

 

 

7. The Sulawesi Warty Pig (S. celebensis)

 

This is a short-faced species, like the Eurasian wild pig, of small size (sample-means of greatest length of skull 256-331 mm in males, females 85.4-90.4% of males in condylobasal skull length in different populations), though there is some evidence of a north (smallest) to south (largest) cline in body size on mainland Sulawesi, extending onto the offshore islands. The species is characterized by its (relatively) very short legs; small, short ears; long, simply tufted, tail; large, heavy head; short, slightly convex, back; and somewhat oblique snout disk. The preorbital wart is typically the most developed of the three pairs, though the gonial wart, which is marked only by a whorl in younger animals, does become obvious late in life and may hypertrophy. The warts remain small in females. The pelage is usually black, often with white or yellow hairs intermixed, but some specimens are predominantly red-brown or even yellowish in color, the underside being uniformly dark in young animals, but becoming paler, eventually light yellow, with age. A distinct yellow snout band is usually present. The mane is rather poorly developed, but forms a conspicuous tuft or 'crest' on the crown, especially in young adult males. Piglets striped to at least six months of age. There are six pairs of mammae.

 

The distribution of this species is most unusual (Fig.15, section 5.7). It occurs as a native form only on Sulawesi and offshore islands (i.e. the Togian Islands, Pulau Salayer, P. Butung, P. Peleng and P. Lembeh), but it has been introduced onto Buru, Halmahera and Seram, and some of the Lesser Sunda Islands (Timor, Flores and P. Roti) and the west Sumatran Islands (Simaleue and Nias) as a domesticated or feral form. Indeed, as Groves has shown, it is evident that the species has been truly domesticated (probably in the early Holocene on Sulawesi), and transported to the Moluccas, where it has also hybridized with S. scrofa, thereby giving rise to the second species of Sus ever to be described, 'S. papuensis', the domestic and feral pig of New Guinea. The so-called 'S. timorensis' (from Timor), 'S. floresianus' (Flores), 'S. mimus' (Simeulue) and 'S. niadensis' (Nias) are also all variously modified celebensis-pigs, some of which are still maintained as domesticates, whilst others (like those on Buru and Seram) were either released to be hunted whenever required for eating or have been allowed to revert to the wild state.

 

 

The Genus Babyrousa

 

8. The Babirusa (B. babyrussa)

 

This extraordinary animal is confined to Sulawesi and some neighboring islands. Three extant subspecies are widely recognized (Groves, 1980). These are:

 

B. b. babyrussa: Buru and the Sula Islands (Mangole, Taliabu and, formerly, Sulabesi).

 

B. b. togeanensis: Togean Islands (Malenge, Talatakoh, Pulau Batudaka, Batone and Pangempong).

 

B. b. celebensis: northern peninsula of Sulawesi at least as far west as Bumbulan and from Pulau Lembeh.

 

A fourth subspecies, B. b. bolabatuensis, described from an early Holocene (?) skull from Bola Batu caves near Watampone, may also survive in still-forested areas of central and south Sulawesi. Indeed, a recent skull from Gunung Melema, Moa, near Kulawi, could be ascribed to this race, though it also resembles the skulls of the Buru and Sula Islands' animals, which may have originated from this region of Sulawesi (see later text).

 

The subspecies differ in size, hairiness and characters of the skull and teeth. Leaving aside the problematical bolabatuensis, nominate babyrussa is the smallest and the hairiest. Indeed, this subspecies is sometimes referred to as the 'golden' or 'hairy' babirusa, on account of its relatively long (>5cm), yellowish pelage, in marked contrast with the barely discernable, short, sparse pelage of the most familiar form, B. b. celebensis, from the (north) Sulawesi mainland. The latter subspecies is also the largest, the Togian Islands', togeanensis, being intermediate in body size between these forms.

 

 

References

 

Groves, C.P. 1980. Notes on the systematics of Babyrousa (Artiodactyla, Suidae), Zool. Meded. Leiden, 55: 29-46.

 

Groves, C.P. 1981. Ancestors for the Pigs: Taxonomy and Phylogeny of the Genus Sus. Tech. Bull., No. 3, Dept. of Prehist., Research School of Pacific Studies, Australian National University: 96pp.

 

Grubb, P. and Groves, C. P. 1983. Notes on the taxonomy of the deer (Mammalia, Cervidae) of the Philippines. Zool. Anz., Jena 219 (1/2): 119-144.

 

Hardjasamita, H. S. 1987. Taxonomy and phylogeny of the Suidae (Mammalia) in Indonesia. Scripta Geol., 85: 1-68

 

Heaney, L. R. 1986. Biogeography of mammals of S. E. Asia: estimates of rates of colonisation, extinction and speciation. Biol. J. Linnean Soc. 28: 127-165.

 

Mudar, K. M. 1986. A morphometric analysis of the five subspecies of Sus barbatus, the bearded pig. (Unpubl.) M. Sc. thesis, Michigan State University.

 

Oliver, W.L.R. 1980. The Pigmy Hog: the Biology and Conservation of the Pigmy Hog, Sus (Porcula) salvanius, and the Hispid Hare, Caprolagus hispidus. Spec. Scien. Rep. No. 1, Wildlife Preservation Trust, Jersey,: 80pp.

 

Sanborn, C. C. 1952. Philippine Zoological Expedition 1946-47. Fieldiana: Zoology, 33: 89-158.

 

Verpmann, H. P. 1987. The ancient distribution of ungulate mammals in the Middle East. Beihefte zum Tübinger Atlas des vorderen Orients, Reihe A (Naturwissenschaften), 27: 1-173.

 

Vigne, J.- D. 1988. Les mammifères post-glaciaires de Corse. Gallia Prehistoire, 26th supp.: 334 pp.

 

 

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