Prosciurillus sp.

Musser, Guy G., Durden, Lance A., Holden, Mary Ellen & Light, Jessica E., 2010, Systematic Review of Endemic Sulawesi Squirrels (Rodentia, Sciuridae), with Descriptions of New Species of Associated Sucking Lice (Insecta, Anoplura), and Phylogenetic and Zoogeographic Assessments of Sciurid Lice, Bulletin of the American Museum of Natural History 2010 (339), pp. 1-260 : 1-260

Prosciurillus sp.

A fragment of a right dentary (fig. 29) from an adult squirrel was found in sediments excavated from Ulu Leang I, a cave about 40 km northeast of Ujung Pandang in the Maros region near the tip of Sulawesi’s southwestern peninsula (see gazetteer and fig. 11). Excavations in the cave were described by Glover (1976), who also provided us with 10,000–3500 years B.P. as a rough interval of the dated sediments (Glover, in litt., 1989). A more precise date associated with the particular site (‘‘Trench J’’) at which the piece was uncovered is unavailable.

The size of the subfossil fragment (the body of the dentary) matches dimensions of the dentaries in members of the Prosciurillus leucomus group and not the two species in the much smaller-bodied P. murinus group (see fig. 29 where the subfossil is compared with a modern member of each group, and table 33 for comparative measurement values). No modern representatives of the P. leucomus group have been collected from Sulawesi’s southwestern peninsula. The sample of P. weberi from Masamba and Palopo on the coastal plain in the far southeastern lowlands of the central core of Sulawesi (see map in fig. 11) is the closest to the provenance of the subfossil. At present we cannot tie the subfossil to P. weberi ; or to P. alstoni , which ranges over the eastern sector of the central core of the island and throughout the southeastern peninsula; or to P. topapuensis , which inhabits forests in the foothills and mountains in the western sector of the central core north of the range of P. weberi (see map in fig. 11); or determine if the subfossil represents a different species restricted to the southwestern peninsula. Dentaries of all these species are closely similar in size and shape, especially the body of the dentary, which is all that remains of the subfossil. Possibly DNA can be extracted from the fragment and compared with samples taken from specimens of the modern species to resolve the issue.

Modern specimens of the small-bodied P. murinus have been collected on the flanks of Gunung Lompobatang at the tip of the southwestern peninsula (see gazetteer and fig. 30). The squirrel likely inhabited lowland forest in the Maros region before the landscape was transformed from forest to agricultural plains and may have been sympatric with Prosciurillus sp. during the 10,000 –3,500 -year interval. The large-bodied Rubrisciurus rubriventer also once occurred on the peninsula, documented by a subfossil cranial fragment (see account of R. rubriventer ).

Archaeological remains of squirrels from caves at the tip of Sulawesi’s southwestern peninsula are extremely rare. Of the more than 1000 specimens of mammals excavated from cave sites at the southern end of the southwestern peninsula during the 1900s (see Dammerman, 1939; Hooijer, 1950; Clason, 1976; Musser, 1984; Simons, 1997), only three squirrels have been noted. One was described by Sarasin (1905) as ‘‘ Sciurus rubriventer ?,’’ a cranial fragment excavated from cave sediments along with skeletal pieces of other mammalian species. The other two were excavated from sediments in Ulu Leang I, the dentary fragment of Prosciurillus we describe here and a ‘‘maxilla’’ listed in a table by Clason (1976: 66); she provided no details. We have not seen Sarasin’s specimen, but his account clearly describes a Rubrisciurus rubriventer . Clason’s material was excavated by Glover from Ulu Leang I mostly during 1973. We do not have access to those specimens. Our dentary fragment was found during Glover’s 1975 excavation of the cave and sent to Musser along with other mammalian fragments.

Clason (1976: 66) tabulated more than 1000 mammalian cranial and postcranial fragments found by Glover in Ulu Leang I (no estimate of the actual number of individuals represented is available). Some were not yet identified at the time of her report, but 852 were given preliminary identifications. Of these, one represents a squirrel, 65 are from non-sciurid rodents, and the rest sample phalangers, bats, primates, carnivores, and artiodactyls. Non-sciurid rodents, especially those of large body size such as the species of Lenomys , Paruromys , and Taeromys are hunted today in other parts of Sulawesi; drift fences made of palm fronds are used with snares placed in openings along the drift

TABLE 33 Measurements (mm) of Alveolar Lengths of Molar Rows (ALpm4–m3) in Dentaries from Samples of a Subfossil and Modern Prosciurillus a Mean ± 1 SD and observed range (in parentheses) are listed for the extant specimens, which are identified in footnotes.

fence (Musser’s observations in central Sulawesi). Likely some of the rodent fragments from Ulu Leang I represent remnants of prehistoric human meals (see Musser, 1984); other pieces are probably from owl pellets, although some could be from the scat of the endemic Sulawesian civet Macrogalidia musschenbroekii . That carnivore may be represented by isolated teeth from Ulu Leang I ( Clason, 1976) and skeletal fragments have been collected from other prehistoric cave sediments in the region ( Hooijer, 1950). In the upper montane forest on Gunung Nokilalaki, Musser frequently saw Macrogalidia and found feces containing cranial and postcranial bits of the murid, Bunomys penitus , which is the most common small rodent in that forest.

In contrast to the murid rodents, all the endemic species of Sulawesi squirrels are diurnal and less exposed to owl predation, although some now and again are likely taken by hawks, eagles, and Macrogalidia . Squirrels are seen but rarely caught by the local people. According to the villagers Musser encountered in the forest, none had ever caught squirrels in their snares set along drift fences. Rather than running alongside a drift fence as rats do, squirrels would simply bound over it. Rats and mice can also be dug out of their burrows, but getting to nests of tree squirrels is more difficult. The prehistoric people living on the southwestern peninsula may have had equal difficulty in capturing squirrels, or it was simply more efficient in time and energy to hunt and capture larger mammals along with rats and mice.