Bunomys Thomas, 1910

Musser, Guy G., 2014, A Systematic Review Of Sulawesi Bunomys (Muridae, Murinae) With The Description Of Two New Species, Bulletin of the American Museum of Natural History 2014 (392), pp. 1-313 : 26-28

Bunomys Thomas, 1910

Frateromys Sody 1941: 260 .

TYPE SPECIES: Mus coelestis Thomas, 1896: 248 .

EMENDED DIAGNOSIS: A genus in Rattini ( Lecompte et al., 2008; Aplin and Helgen, 2010) or Rattus Division ( Musser and Carleton, 2005) of Murinae within Muridae (as delimited by Musser and Carleton, 2005) that is distinguished from all other described murine genera by the following combination of traits: (1) all species terrestrial in habitus; (2) dorsal pelage covering head and body dense and soft, with guard hairs only slightly longer than overhairs, so coat has an even surface, dorsal coat dark gray, dark bluegray, brownish gray or brown speckled with buff and black; (3) ventral coat soft and dense, whitish gray, dark grayish white, bluegray lightly speckled with white, grayish pale buff to ochraceous gray, demarcation between upperparts and underparts inconspicuous; (4) muzzle elongate in most species, ears rubbery in texture, gray to brown; (5) tail shorter than combined length of head and body, coequal or slightly longer (mean values of LT/ LHB range from 79 % to 102 %), scales small, their annuli overlapping, three short hairs associated with each scale, dorsal surface grayish bown to brown, ventral surface ranges from white (tail is bicolored) to brown (tail is monocolored), a white tip occurs infrequently or is usual, depending upon the species; (6) digits white, dorsal surfaces of carpal and metacarpal regions white to brown, palmar surface adorned with usual number of tubercles found in murines (three interdigitals, a thenar, and a hypothenar), hind foot elongate with full complement of plantar tubercles (four interdigitals, a thenar, and a hypothenar), front claws elongate in three species; (7) two pairs of inguinal teats; (8) testes of adults large relative to length of head and body (22 %) or smaller (8 % –15 %); (9) rostrum of adults elongate and either narrow or broad, interorbital and postorbital margins bounded by low ridges, zygomatic arches flare from sides of skull, posterior zygomatic root situated low on braincase, braincase boxlike (moderately wide and deep), occiput deep, no cranial flexion; (10) zygomatic plate wide or narrow, its anterior margin either barely projecting beyond dorsal maxillary root of zygomatic arch or bowed beyond it, its posterior edge even with the anterior third of the first molar; (11) squamosal intact (not perforated by a subsquamosal foramen); (12) alisphenoid struts absent; (13) incisive foramina long in most species and moderately wide, their posterior margins ending well anterior to front faces of first molars; (14) molar rows diverge slightly posteriorly, bony palate short with its posterior margin even with back faces of third molars or extending slightly beyond them, palatal surface with moderately deep palatine grooves, posterior palatine foramina at level where second and third molar touch; (15) moderately long and narrow sphenopalatine vacuities; (16) wide pterygoid plates with moderately deep pterygoid fossa, small sphenopterygoid openings; (17) medium or large ectotympanic (auditory) bulla relative to skull size, capsule incompletely covering periotic, posterodorsal wall of carotid canal formed by periotic and not bullar capsule; (18) large stapedial foramen, no sphenofrontal foramen or squamosal-alisphenoid groove, indicating a carotid arterial pattern widespread within Murinae (char. state 2 of Carleton, 1980; pattern 2 described by Voss, 1988); (19) dentary somewhat elongate, low ramus between incisor and molar row, moderately high ascending ramus, large coronoid and condyloid processes, end of alveolar capsule forming modest labial swelling level with base of coronoid process; (20) upper and lower incisors with orange enamel and ungrooved anterior faces, uppers emerge from the rostrum at a right angle (orthodont) or curve slightly caudad (opisthodont), each lower incisor awl shaped with elongate wear facets; (21) each first upper (maxillary) molar with five roots, the second with four, and the third with three, each first lower (mandibular) molar with four, the second and third molars each with three; (22) molars brachydont, cusp rows forming simple cuspidate occlusal patterns, third molar small relative to others in toothrow; (23) first and second rows of cusps on first upper molars laminarlike or gently arcuate because cusp t3 on the first row and cusp t6 on the second row are oriented horizontally and broadly coalesced with the respective central cusp t2 and cusp t5, anterior row of second molar shaped like second row of first molar; (24) no cusp t7 or posterior cingulum on upper molars, and no other occlusal embellishments (such as an enamel ridge projecting from anterolingual surface of cusp t8 anteriorly to posterior margin of lingual cusp t4, a labial enamel ridge connecting anterolabial margin of cusp t9 with posterolabial margin of cusp t6, or a comparable but shorter ridge projecting from the anterior surface of cusp t5 to meet the posterior margin of cusp t3 near the cingulum, all typical of some other murines with more complicated enamel occlusal patterns; the New Guinea Coccymys is an example [ Musser and Lunde, 2009]), cusp t3 typically missing from second molars in all but two species and from third molar in most specimens; (25) anteroconid formed of large anterolingual and anterolabial cusps, anterocentral cusp absent, anterolabial cusp present or missing from second and third lower molars depending upon the species, anterior labial cusplets typically not present on first and second lower molars, but posterior labial cusplet present on each tooth, posterior cingulum round or elliptical; (26) stomach unilocular-hemiglandular; (27) sperm head asymmetrical and falciform in shape, with single apical hook lacking ventral processes, spermatozoal tail short to moderately long; and (28) karyotype, 2N 5 42, FNa 5 56 or 58, FNt 5 58, 60, or 61.

CONTENTS: Bunomys chrysocomus , B. coelestis , B. prolatus , B. torajae , n. sp., B. fratrorum , B. andrewsi , B. penitus , and B. karokophilus , n. sp.; all are endemic to Sulawesi.

GEOGRAPHIC AND ELEVATIONAL DISTRI- BUTIONS: One species is spread over the island, the others restricted to certain regions (table 5; also see the maps showing collection localities in figs. 22, 50, and 51). Bunomys chrysocomus is the most widespread (as documented by voucher specimens): samples are from the central core and most of the peninsulas and were collected through an elevational range bracketed by lowland to montane habitats. Bunomys coelestis is known only from montane forest on Gunung Lompobatang, the highest landform in the southwestern peninsula; the montane B. prolatus has been taken to date only from Gunung Tambusisi at the western terminus of the eastern peninsula; and B. torajae , n. sp., has been collected so far only from montane habitat on Gunung Gandangdewata in the southern section of the west-central mountain block. Bunomys fratrorum is endemic to the northern peninsula east of the Gorontalo area where it occupies tropical lowland evergreen and montane rainforest habitats. Bunomys andrewsi occurs primarily in tropical lowland evergreen rain forests and is represented by voucher material from the Sulawesi’s core, the western end of the eastern peninsula, and the southeastern and southwestern peninsulas. Bunomys penitus is strictly montane, found so far only in the west-central mountain block and in Pegunungan Mekongga on the southeastern peninsula. The only samples of B. karokophilus , n. sp., come from tropical lowland evergreen rain forest at middle elevations in the northern portion of the west-central region.

COOCCURRENCE AMONG THE SPECIES: The patterns of sympatric or parapatric geographic distributions as well as syntopic occurrences among the species of Bunomys is summarized in table 6 and elaborated in the accounts of species.

DESCRIPTION: Morphological variation categorizing the species of Bunomys reflects rats of medium body size (fig. 6; table 7) adapted to terrestrial habitats. The general character variation as expressed in live animals and preserved specimens is described below under external form (fur, ears, tail,

TABLE 5

Summary of Elevational Distributions (m) over Mainland Sulawesi for Species of Bunomys derived from Voucher Specimens

See the maps showing collection localities in figures 22, 50, and 51.

feet, teats, and testes), gross spermatozoal morphology, gross stomach structure, skull, and teeth. Each species is characterized by its own combination of traits and these will be addressed in the accounts of species.