Acrobates pulchellus Rothschild 1892
Creators: name: P. Aplin, Kenneth
name: N. Armstrong, Kyle
name: M. Aplin, Lucy
name: Jenkins, Paula
name: Ingleby, Sandra
name: Donnellan, Stephen C.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Diprotodontia
Acrobatidae
Acrobates
Acrobates pulchellus

description: Acrobates pulchellus Rothschild, 1892
Type specimens. [designation by Thomas (1922)]: The lectotype (NHMUK 1888.3.17.1; an adult male) and paralectotype (NHMUK 1888.3.17.2; an adult female) of A. pygmaeus (Shaw, 1794) are spirit preserved bodies, the lectotype with the skull extracted and in good condition, the paralectotype with cranium in situ.
Diagnosis. Tail furred ventrally to the end, tipped with a small nubbin of naked skin (Fig. 3A); terminal pads of pedal digits 4 and 5 rounded, sub-equal in length and width, and with narrow distal groove; base of hallux with two distinct raised pads, both bearing striae (Fig. 3C); tail fringe hairs usually with a 1–2 mm wide cream emargination; ventral fur grey-based with cream tips, most individuals with entirely cream or white fur on throat and upper chest, rarely extending to lower abdomen (Fig. 4). The ear canal disc, in external view, occupies between 60 and 70% of the width of the tympanic canal, has a raised narrow central ridge from the base that projects between 50 and 80% of the width of the disc. The disc in the internal view lacks sculpturing (Fig. 5).
Description. Body measurements based on mature adults are presented in Table 3. Small body size, up to 20 g and 85 mm head-body length. Flanks with a narrow patagium, running along the limbs and flank from the wrist to the knee.
Soft and silky fur, greyish brown dorsally (Fig. 4 F-I). Most individuals with entirely cream or white fur on throat and upper chest, rarely extending to lower abdomen, otherwise ventral fur grey-based with cream tips (Fig. 4 F-I). Colouring sharply demarcated at the edge of the patagium.
Tail equal in length to the head and body (mean = 1.08). Tail markedly distichous and oval in cross-section, with very short ashy-brown fur on the upper and lower surfaces, paler below than above. Tail furred ventrally to the end, tipped with a small nubbin of naked skin. Broad fringe of stiff long hairs along each side (about 8 mm in length), tail fringe hairs usually with a 1-2 mm wide cream emargination.
The eyes are large, dark and encircled with black fur. The rhinarium is naked, flesh coloured, and deeply cleft; the nostrils are lateral.
The ears are moderately large, flattened, oval, and moderately furred externally.
Long vibrissae, unusually numerous, extend from the snout, cheeks, and base of each ear with shorter vibrissae extending from the chin.
Hands and feet brown above, feet well furred, hands thinly furred. Terminal pads of pedal digits 4 and 5 rounded, subequal in length and width, and with narrow distal groove; base of hallux with two distinct raised pads both bearing striae (Fig. 3C).
Manual digits of relatively similar length in the following order 4>3>2>5>1. Palmar surfaces hairless, with four broad low pads, three at the base of the fingers and one at the base of the palm. Length of pedal digits in the following order 4>5>3>2>1. Plantar surfaces hairless with five small pads, four at the base of the toes and one at the base of the foot. Tips of the toes with flattened and striated pads, those on the syndactylous toes 2 and 3 separate and well developed, but smaller than the others. Syndactylous toes 2 and 3 united only to the ends of the first phalanx. Claws sharp and well developed, small in comparison with finger and toepads.
Dentition diprotodont. The homology of the anterior dentition of the mandible is not yet determined (Aplin 2015; Kelt and Patton 2020). The dental formula is currently described as I 3/1, C 1/1?, P 3/3? M 3/3 = 20+16=36 (Fig. 6), based on examination of five vouchers (ANWC M3745, M6184, M24072, NHMUK 88.3.17.1, NHMUK 1939.2988). We note that the dental formula we have observed is at variance with previous descriptions in Harris (2015), Nowak (2018), Thomas (1888), but consistent with the dental formula in an illustration of the cranium and dentary of AMS M 3294 in Harris (2015).
Variation in cranial and dental morphology is illustrated in Fig. 6 and Supplementary Fig. S2. We note that the description of cranial and dental morphology for Acrobates in Thomas’ (1888) account is likely based on a composite series of both species of Acrobates given the collection locations he listed for the 17 specimens he had available. Recently, Fabian et al. (2023), in describing several fossil acrobatids, carried out a comparison of dental morphology of extant and extinct acrobatids. From their appendix of material examined we were able to determine that they examined dentaries from 12 specimens of A. pygmaeus and 24 A. frontalis (Supplementary Table S1). Fabian et al. (2023) effectively had done a “blind” analysis of dental variation in that they did not identify the vouchers to species level prior to their examination and subsequently stated that: “we did not detect significant variation in the dental features we examined, including in m1 morphology (see Results). We conservatively refer to all of these specimens as A. pygmaeus ”.
Distribution. Broadly distributed across forested and wooded regions of south-eastern Australia, including: the south-eastern corner of South Australia; Victoria with the exception of the inland draining catchments of the Murray Basin; the Great Dividing Range of New South Wales, north to the Border and McPherson Ranges in south-eastern Queensland; and the coastal drainages of the Great Dividing Range, north at least to the Wallamba River, Tuncurry—AMS M25806 (Fig. 7). Acrobates pygmaeus is regionally sympatric with A. frontalis throughout its entire range, with numerous instances of syntopy at the level of museum locational data (Supplementary Table S1).
Remarks. The lectotype and paralectotype of Didelphis pygmaea Shaw 1794 are leached of all pigment and stained a uniform brown colour. The lectotype is in poor condition, with much of the fur stripped from the venter and from the tail. The manus and pes are clenched and dehydrated, and no details of the plantar surface are discernible. However, the terminal pads of pedal digits 4 and 5, while folded and somewhat shrivelled, seem to be relatively unexpanded and thus consistent with Acrobates pygmaeus rather than A. frontalis.
The holotype of Acrobates pulchellus Rothschild, 1892 (NHMUK 1939.2988) is a well-preserved puppet skin and a cleaned skull which lacks the rear part of the skull Supplementary Fig. S2 B). The purplish-brown colour of the dorsal fur, noted as a diagnostic feature by Rothschild (1892), falls within the observed variation of both species. The tail is short but the density of ventral fur at the tip leaves us in no doubt that it is damaged, possibly to a significant degree. The pes is consistent in morphology with A. pygmaeus, featuring relatively small, ovate terminal pads on each of digits IV-V and a prominent accessory hallucal pad on which the striae are clearly visible. The extensively grey-based ventral pelage of NHMUK 1939.2988, though not strictly diagnostic at species level, nonetheless is also consistent with the typical condition in A. pygmaeus.
Our assessment of the holotype of A. pulchellus supports and extends the previous findings of Tate (1938). In all morphological respects, including the morphology of the skull and teeth examined by Tate (1938), the purportedly New Guinean holotype of Acrobates pulchellus resembles A. pygmaeus of south-eastern Australia, rather than northern populations of A. frontalis. Like Tate, we favour the view that the locality details accompanying NHMUK 1939.2988 are spurious and that it was derived from somewhere in south-eastern Australia, a conclusion that could be tested further by DNA sequencing of the holotype.
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ABTC, Australian Biological Tissue Collection, South Australian Museum; AMS, Australian Museum; ANWC, Australian National Wildlife Collection; QM, Queensland Museum.;
SAMA, South Australian Museum. ACAD—DNA extract sample number at the Australian Centre for Ancient DNA, University of Adelaide; S1—short (148bp) BRCA1 sequences are in the Supplementary Text S1 file; S2—short (96bp) 12S rRNA sequences are in the Supplementary Text S2 file.
Because of the extensive regional sympatry of the two species of Acrobates in south-eastern Australia, retrospectively identifying which species was used in published studies of Acrobates could be problematic. For instance, Ward (1990) reported four mammae in Acrobates but the specific identity of the material he examined is not known. A possible exception would be for studies carried out on the Southern Tablelands of New South Wales at elevations above 600 m.
description: Published as part of P. Aplin, Kenneth, N. Armstrong, Kyle, M. Aplin, Lucy, Jenkins, Paula, Ingleby, Sandra & Donnellan, Stephen C., 2025, Hidden diversity in an ecologically specialized genus of Australian marsupials, the feather-tailed gliders, Acrobates (Diprotodontia, Acrobatidae), pp. 535-564 in Zootaxa 5566 (3) on pages 546-553, DOI: 10.11646/zootaxa.5566.3.5, http://zenodo.org/record/14703409