Ecology, Conservation and Management of Wild Pigs and Peccaries

Part II: Species Accounts

176

Taxonomy

Bearded pigs display a wide range of sizes, colours, and sexual

dimorphism, obscuring historical attempts at morphological

species delineations (Miller 1905). Genetic information has more

recently helped to redraw the lines between species and subspe-

cies. In 2001 the Palawan bearded pig (Sus ahoenobarbus) was

moved from a barbatus subspecies to a new species (Groves 2001).

In 2005 the Sumatra subspecies of bearded pig, Sus barbatus oi,

was shown to have separation from the Peninsular Malaysia and

Borneo populations (Sus barbatus barbatus; Lucchini et al. 2005).

Subspecies and Distribution

The two subspecies are distinguished by their ranges: S. barbatus

oi is native to Peninsular Malaysia and Sumatra while S. barba-

tus barbatus is endemic to Borneo (including Brunei), as well

as Borneo’s near-shore islands (e.g. Sibutu Island in the west-

ern Sulu Archipelago). However, genetic and morphological

phylogenetic analyses indicate that the Sumatran S. barbatus

oi populations show significant but incomplete genetic sepa-

ration from bearded pigs in the other two regions (Lucchini

et al. 2005), and this may warrant further taxonomic revision.

Historically, bearded pigs were found on many near-shore

islands (Lyon 1908, 1911; Meijaard 2000) and individuals from

islands east of Sumatra (e.g. Bangka and Palau Bintang in the

Riau Archipelago) share genetic attributes of both subspecies

(Lucchini et al. 2005). This is unsurprising given the islands’

recent separation (~10,000 years since the last glacial maximum)

and bearded pigs’ propensity for long-distance swimming,

including in the open ocean (Wallace 1869; Caldecott et al. 1993;

Hanebuth et  al. 2000). It is also likely that bearded pigs peri-

odically crossed the straits of Melaka that separate Peninsular

Malaysia and Singapore from Sumatra (< 30 km wide), limiting

further differentiation of the Sumatran population and explain-

ing the presence of hybrids on Riau’s islands. However, the

extensive forest loss in the coastal areas of north-east Sumatra

and south-west Peninsular Malaysia now inhibits gene flow

Figure 18.1). There are no reports of bearded pigs persisting on

the near-shore islands around Borneo, Peninsular Malaysia, or

Singapore (Ke and Luskin 2017).

Within Sumatra, the complete absence of S. barbatus oi from

the expansive forests of Gunung Leuser, the northern Barisan

mountains, and Ulu Masen remains a mystery. In fact, bearded

pigs have never been documented north of Kota Pinang (along

Riau province’s northern border). Notably, there is a paral-

lel gap in the range of the Malayan tapir (Acrocodia indica;

Figure 18.1 Bearded pig distribution (source: IUCN 2008, Red List of Threatened Species; Ke & Luskin 2017). (A simplified black and white version of this figure will appear in

some formats. For the colour version, please refer to the plate section.)

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