Article

Squirrels

From Munshipedia, the MBRAS digital historical encyclopedia

Squirrels

Squirrels of the genus Sciurus and its close relatives constitute a diverse and widespread group across the Malay Peninsula and Borneo, encompassing multiple species and subspecies that have attracted sustained taxonomic attention from naturalists working in the region. The red-bellied squirrel (Sciurus vittatus), the coconut squirrel (Sciurus notatus), the black-and-red squirrel (Sciurus prevosti), and the rare Glyphotes simus all occur within the area, each presenting distinct challenges of classification, distribution, and morphological variation that have occupied researchers from the early twentieth century onward [1], [2], [3], [4], [5].

Taxonomic Framework and Species Groups

The squirrel fauna of the region is organised around several major species groups, each with its own pattern of geographic differentiation. The red-bellied squirrel, Sciurus vittatus, is divided into two principal subspecies groups: miniatus, the continental form characterised by rufous tail-tips, and vittatus, the island and southern form with annulated tail-tips [1, p. 57]. This distinction between continental and island populations has proven a recurring theme in the taxonomy of the genus, with island forms frequently showing reduced or modified colour patterns relative to their mainland counterparts.

The coconut squirrel, Sciurus notatus, represents a separate lineage within the same general region. Kloss (1926) placed the new subspecies S. n. guillemardi from Pulau Tenggol within the vittatus section of notatus, noting its approximate size equivalence with S. scotti from Little Redang and S. famulus from Pulau Dayang [5, p. 260]. The taxonomic placement of these small island forms within the broader notatus complex reflects the difficulty of distinguishing closely related insular populations that differ primarily in subtle colour and cranial characters.

The black-and-red squirrel, Sciurus prevosti, presents a more complex taxonomic situation spanning Sumatra and Borneo. Chasen and Kloss (1925) argued that the black-and-red squirrel of northern Sumatra, S. piceus Peters, is a strongly differentiated race of S. prevosti, linked to the typical three-coloured form by the intermediate S. nyx Miller from Rupat Island, which retains a vestigial buffy side stripe [2, p. 98]. In Borneo, the situation is further complicated by the presence of S. pluto Gray (from Sabah, Kinabalu, and Gantian) and S. rufoniger Gray (from Labuan), which the authors regarded as two colour phases that may be dimorphic forms of a single species, each divisible into geographic races [2, p. 99].

A separate and rarer element of the Bornean squirrel fauna is Glyphotes simus Thomas, a species treated as distinct from the Sciurus group on cranial and dental characters [3], [4]. Kloss (1921) explicitly distinguished his new species Sciurus adamsi from Glyphotes simus on these same cranial and dental grounds, as well as on the distinctness of postauricular patches [4, p. 151].

Subspecific Differentiation and Island Forms

A dominant theme in the documented literature is the differentiation of squirrel populations on islands from their mainland relatives. Chasen and Kloss (1924) described three new races of Sciurus vittatus from islands in the Malay Peninsula and the Rhio Archipelago, each distinguished from the continental miniatus group by modifications in tail colouration and lateral stripe characters [1, pp. 57–58]. S. v. lighti, from Penang Island, is distinguished from mainland miniatus by a less extensive rufous tail area and a dark lateral stripe that is shorter, less black, and grizzled with tawny [1, p. 58]. S. v. stellaris, from Bintang Island in the Rhio Archipelago, is a peninsularis-group form with a notably darker, more blackened back [1, p. 58]. S. v. lunaris, from Bulan Island in the same archipelago, differs from stellaris in having slightly less rufous underparts, greyer facial sides, a creamy rather than buff pale lateral stripe, and a paler tail [1, p. 58].

Kloss (1926) described a further island form, S. n. guillemardi from Pulau Tenggol on the east coast of the Malay Peninsula, which he distinguished from related forms by its darker rufous underparts and tail tip, a richer buff in the pale elements of the upper parts, and a broader lateral stripe [5, p. 260]. Cranially, the new subspecies resembles S. famulus in rostrum length and in the posterior extent of the nasals relative to the premaxillaries [5, p. 260]. Kloss noted that one of the four specimens examined showed reduced dark lateral stripes obscured with rufous, suggesting a possible parallel with colour tendencies observed in races from the more northern Trengganu islands [5, p. 260]. This observation points to a broader pattern of colour variation among the small island populations of the east coast, though the authors did not pursue the matter further.

Species Descriptions from Borneo

The Bornean records contribute two significant species-level descriptions. Kloss (1921) described Sciurus adamsi from North Sarawak, based on two specimens collected by Major J. C. Moulton [4, p. 151]. The type is an adult female from Long Mujan, approximately 150 miles up the Baram River at an elevation of 700–900 feet, with a head-and-body length of 176 mm [4, p. 152]. Kloss distinguished the new species from the superficially similar Sciurus vittatus dulitensis on the basis of smaller size, brighter colouration, and the presence of large buff postauricular patches, and from Glyphotes simus on cranial and dental characters and the distinctness of those patches [4, p. 151]. The species was named in honour of C. D. Adams, District Officer, Baram [4, p. 152].

The rare Bornean squirrel Glyphotes simus Thomas was the subject of a separate note by Chasen and Kloss (1927), published as Records of the Raffles Museum No. 27 [3]. The record confirms the species’ treatment as a distinct taxon within the Bornean squirrel fauna, though the available source evidence does not permit further elaboration on the specific content of that note.

Research and Documentation

The documented literature on squirrels in this region is concentrated in a relatively narrow window from 1921 to 1927, with the bulk of the work attributable to C. Boden Kloss, either alone or in collaboration with F. N. Chasen. Kloss’s early contribution, the description of Sciurus adamsi in 1921, was published in the JSBRAS under the auspices of the Straits Branch of the Royal Asiatic Society [4]. From 1924 onward, the work appears in the JMBRAS under the Malayan Branch, and is consistently issued as part of the Records of the Raffles Museum series, indicating a close institutional relationship between the Society’s journal and the museum’s curatorial output [1], [2], [3], [5].

The methodological approach is uniformly taxonomic and morphological: each contribution is a short note describing new taxa or clarifying existing classifications on the basis of colour, cranial measurements, and dental characters. There is no evidence in the available records of ecological, behavioural, or economic studies of squirrels in this period. The priority given to subspecific differentiation—particularly of island forms—reflects the broader zoogeographical interests of the era, in which the differentiation of insular populations from continental stock was a central concern. The question of whether Bornean and Sumatran black-and-red squirrels represent a single species or distinct taxa remained explicitly unresolved, with Chasen and Kloss calling for further distributional data [2, p. 99]. The body of work, while limited in scope, establishes a baseline of taxonomic knowledge against which subsequent research on the region’s squirrel fauna would necessarily build.

MBRAS Sources

References

  1. F.N. Chasen and C.B. Kloss (1924). Three new races of Sciurus vittatus. F.N. Chasen and C.B. Kloss. Records of the Raffles Museum, No. 1 JMBRAS 2(1): 57–58.
  2. F.N. Chasen and C.B. Kloss (1925). Remarks on the black and red squirrels allied to Sciurus prevosti. F.N. Chasen and C.B. Kloss. Records of the Raffles Museum, No. 11 JMBRAS 3(1): 97–99. Read on JSTOR
  3. F.N. Chasen and C.B. Kloss (1927). A rare Bornean squirrel, Glyphotes simus Thomas. F.N. Chasen and C.B. Kloss. Records of the Raffles Museum, No. 27 JMBRAS 5(2): 349–350.
  4. C.B. Kloss (1921). A new squirrel from North Sarawak JSBRAS 83: 151–152. Read on JSTOR
  5. C.B. Kloss (1926). A new squirrel from Tenggol Island, east coast of the Malay Peninsula. Records of the Raffles Museum, No. 23 JMBRAS 4(2): 259–261.