224.

Lowland Sulawesi Ranee Mouse

Haeromys minahassae

French: Haeromys de Minahasa / German: Sulawesi-Zwergbaummaus / Spanish: Raton rani de Célebes

Other common names: Lowland Sulawesi Haeromys, Minahassa Ranee Mouse, Minahassa Haeromys

Taxonomy. Mus minahassae Thomas, 1896,

“Rurukan, Minahassa, N. Celebes,” Sulawesi Island, Indonesia .

When O. Thomas described this species in 1896, he noted a general resemblance to margarettae from Borneo but regarded its narrow hindfeet as more like those of a typical mouse, unlike the broadened feet of any arboreal murine:. Subsequently, fresher material demonstrated close affinity of these species, which he grouped in genus Haeromys . A Sentaxonomic revision of available specimens of H. minahassae has not been published, but G. G. Musser in 1990 suggested that minor contrasts in fur coloration between samples from northern and central Sulawesi were not indicative of more than a single species on Sulawesi. Subsequently, Musser and M. D. Carleton in 1993 mentioned the presence of material of a second, unnamed species of Haeromys from montane localities in Sulawesi; this species remains undescribed. Monotypic.

Distribution. Recorded from two isolated regions in N & C Sulawesi, at elevations of 75-1005 m.

Descriptive notes. Head—body 70-78 mm,tail 120-131 mm, ear 15-16 mm, hindfoot 19-21 mm; weight 12-15 g. The Lowland Sulawesi Ranee Mouse is the smallest native rodent on Sulawesi. It has a broad head with short snout and moderately large eyes. Body proportions are unexceptional, but tail is long and slender, rather whiplike in appearance. Fur on upperparts is soft, long, and dense, lacking distinct spines. Color described in 1896 by Thomas as “rufous, duller on the back, brighter on the sides. Under surface white, bases of the hairs gray; line of demarcation on sides wellmarked.” Underside is pure white to roots in specimens from central Sulawesi. Ears are moderately large, rounded, and with dark pigmented skin. Lower part of forelimb, wrist, and forefoot white. Lower hindlimbs and upper surface of hindfeet brown apart from digits, where skin and hairs are white. Forefeet with nail on first digit, and “short, sharp, curved claws” on remaining digits. Hindfeet are moderately elongate but broad, with plantar pads “six in number as usual, not striated, the posterior one elongate.” First digit moderately long, reaching to base of second digit, and with a minute claw rather than a nail; remaining digits all with short, curved claws. Tail is long and slender (160-180% of head-body length), and brown above and below; basal portion oftail is thinly furred, but remainder finely haired, almost naked in appearance, and with very small scales, averaging c.23-25 rows/cm. Cranium has globular braincase, with very short, narrow rostrum and delicate zygomatic arches. Three molars are present in each series,all very reduced but with cuspidate crown morphology. Mammae three on each side, one post-axillary and two inguinal. Autosomal complement includes 21 pairs of acrocentric chromosomes in graded series from large to small, and two pairs of small metacentric. Presumed X chromosomeis a large submetacentric, and presumed Y chromosome a medium-sized acrocentric. Spermatozoa with moderately long tail (115 pm), and relatively short (9-5 pm) sperm head with broad lateral face (4 pm) and single short (4 pm) apical hook; an unusual feature is a small ventral spike, locatedjust above connecting piece of sperm tail. Chromosomal complement has 2n = 48, FN = 54.

Habitat. Natural habitat of Sulawesi lowlands and hill zone is evergreen tropical lowland rainforest. Vicinity of Rurukan has long supported a mosaic of agriculturalfields and remnant forest. Lowland rainforest habitat of the Lowland Sulawesi Ranee Mouse in forested slopes above Kuala Navusu (at 75-150 m) in central Sulawesi was described and illustrated by Musser and M. Dagosto in 1987.

Food and Feeding. Diet reportedly includes fruits of herau palms ( Areca vestiaria, Arecaceae) and figs ( Ficus). Pulp of the palm fruit is consumed, but pulp of figs is discarded and seeds alone eaten. This is unusual as seeds offigs are more commonly passed in the feces of regionally co-occurring murids, and it is the pulp that provides the nutrition. This role as a “seed predator” might be regarded as a pre-adaptation for granivory.

Breeding. No information.

Activity patterns. Lowland Sulawesi Ranee Mice are nocturnal and scansorial. In 1990, Musser described capture of individuals within tangles of woody vines. Ranee mice are agile climbers, but appear not to use the tail in prehensile grasping fashion but rather as a counterbalance and stabilizer.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Vulnerable on The IUCN Red List. A recent survey of habitat condition in Sulawesi found that more than 80% of original lowland rainforest has been converted for subsistence agriculture and plantations, with less than 3% of the especially biodiverse alluvial forests remaining. Forestry and other forms of disturbance have heavily impacted much of remaining forest cover at low elevations, and this has no doubt resulted in fragmentation of remaining populations.

Bibliography. Ellerman (1941), Musser (1990), Musser & Carleton (1993, 2005), Musser & Dagosto (1987), Musser & Ruedas (2008i), Thomas (1896a, 19111).