Ground cuscus

Abstract: A region of mitochondrial DNA, including the 3′ end of tRNA phenylalanine, the complete 12S rRNA and tRNA valine genes, and the 5′ end of 16S rRNA, was sequenced for four phalangerids and one burramyid; additional marsupial sequences were extracted from GenBank. Parsimony, minimum evolution, and maximum likelihood analyses show that the ground cuscus, Phalanger gymnotis, groups with the tribe Phalangerini, not with the tribe Trichosurini as had been suggested on the basis of certain morphological characters. This result is in agreement with an earlier study using DNA hybridization and is supported by some morphological evidence as well. We conclude that the character states that link the ground cuscus with the Trichosurini are the result of convergence, and therefore the placement of several other species in the trichosurin genus Strigocuscus based on the same characters should be reconsidered. The hypothesized close relationship of two fossil taxa, Strigocuscus reidi and S. notialis, to Phalanger gymnotis is also questionable because the fossils do not share morphological synapomorphies that link the ground cuscus to the Phalangerini.

Abstract: DNA-hybridisation experiments, involving seven species of Phalangeridae and two outgroup taxa in a complete 9 x 9 matrix, unequivocally placed the bear cuscus, Ailurops ursinus, nearest to the Phalangerini (Phalanger and Spilocuscus), with Trichosurini (Trichosurus) sister to both; and confirmed earlier molecular studies indicating that the ground cuscus, Strigocuscus gymnotis, is not a trichosurin but is closest to Phalanger. Our results thus conflict with the most thorough cladistic-anatomical study of phalangerids, which placed the bear cuscus outside all other Phalangeridae as the sole living member of Subfamily Ailuropinae; instead, we suggest that Ailurops should be considered representative of a tribe of Phalangerinae, Ailuropini, while Trichosurus (and presumably Wyulda, which was not examined here, as well as fossil Strigocuscus) would be removed from Phalangerinae and be considered a second subfamily of Phalangeridae, Trichosurinae, limited to Australia. Our estimate of the time of divergence of Ailurops and other phalangerines is about 16 myrbp; of Trichosurinae and Phalangerinae, about 21 myrbp. Thus, a single Early Miocene vicariant event between Australia and Papua New Guinea, which isolated phalangerines in the latter region, followed by dispersal of the included ailuropins to (or vicariant separation on) Sulawesi, would be sufficient to account for family-level cladogenesis in Phalangeridae.

Abstract: A 15-year-old female ground cuscus (Phalanger gymnotis) was presented with an isolated ulcerated, nonhealing lesion on the lateral thorax. Histopathology and immunohistochemistry were diagnostic for cutaneous T-cell lymphoma with incomplete excision. Oral chemotherapy with CCNU (lomustine) resulted in clinical remission that lasted 255 days, with no appreciable toxicity. Tumor recurrence was treated with radiation therapy, which resulted in 120 additional days of clinical remission. Subsequently, the tumor developed at a distant site and the cuscus was humanely euthanized. A slight decrease in appetite early in disease progression was the only adverse effect noted throughout the treatment period. Oral, minimally invasive chemotherapy, and adjunct radiation therapy were viable treatment options for this ground cuscus and should be considered for treatment of neoplasia in other nontraditional species.

Abstract: Digestive-tract morphology and function were studied in the ground cuscus (Phalanger gymnotis), reported to be the most frugivorous of eight species of New Guinean phalangerid marsupials. When offered a mixed diet of fruit and foliage, captive animals selected a diet of more than 90% fruit. Fibre digestibility was low and variable, but apparent digestibilities of both dry matter (90%) and energy (87%) were high, and intake of digestible energy was similar to that of the Australian phalangerid Trichosurus vulpecula (common brushtail possum) in captivity. The small intestine of P. gymnotis was the longest and heaviest region of the gastrointestinal tract, but the stomach contained more digesta. The total nitrogen content of digesta was low in the stomach and small intestine, but increased four-fold in the hindgut, because of microbial activity. No difference in nitrogen concentration or in the proportions of small or medium particles was found along the hindgut, but the caecum contained a smaller proportion of large particles than the distal colon. The transit time of a large particle marker was much longer than that of a solute marker, but mean retention times (MRTs) of the two markers did not differ. Both transit times and MRTs were long relative to those reported in T. vulpecula. Although fermentation rates in the caecum and proximal colon were similar to those in T. vulpecula on a foliage diet, fluid volumes were less than one-third those of T. vulpecula, and, consequently, daily production of short-chain fatty acids (SCFAs) was less than half that in T. vulpecula, and contributed only 5% of digestible energy intake (v. 15% in T. vulpecula). These results are consistent with reports that the natural diet of P. gymnotis is based largely on fruit rather than on foliage.