Phascogale tapoatafa wambenger Rhind & Aplin

Have, Ten, 2015, Taxonomic revision of Phascogale tapoatafa (Meyer, 1793) (Dasyuridae; Marsupialia), including descriptions of two new subspecies and confirmation of P. pirata Thomas, 1904 as a ‘ Top End’ endemic, Zootaxa 4055 (1), pp. 1-73 : 35-37

Phascogale tapoatafa wambenger Rhind & Aplin subsp. nov.

Holotype: WAM 7674. Adult male. Quindalup, Western Australia, 33 0 40 S’ 115 0 00’ E. Collected by Mr R. C. Hislop, 17th March 1967. Puppet skin and skull .

Paratype: WAM 5006. Adult female. Balingup Brook, Western Australia, 33 0 41’ S 116 0 05’ E. Collected by Ms J. Kyd, 17th March 1962 .

Etymology. The word ‘wambenger’ is in common local use in southwestern Western Australia for the Brushtailed Phascogale . The name is listed by Dixon (1990; cited by Bindon & Chadwick 2002) as an ‘Australian Aboriginal Word in English’, and identified as ‘possibly Nyungar’ in origin. Bindon & Chadwick (2002) gave the transliteration wam-bing-ga, following the usage of Isaacs (n.d.) in a work evidently compiled prior to 1949. Isaacs’ source is not specified and there appear to be no earlier published records of the word. Bindon & Chadwick (2002) report two other Nyoongar words for 'squirrel'— kumining and comingcoming— either of which might be applicable to the Phascogale which is the most ‘squirrel-like’ of the native mammals of the region.

Diagnosis. A moderately large-bodied race of P. tapoatafa that differs from the typical race of southeastern Australia in the following ways: externally, with a narrower zone of cream-tipped fur on venter, cream preauricular patch rarely developed, generally longer tail brush, slightly larger pinnae, less densely furred muzzle, narrower zone of contrasting pale fur on inside of fore- and hind-limbs, variable number (6–8) and commonly fewer teats; cranially, very similar to nominotypical P. tapoatafa but with less prominent sexual dimorphism in canine size (reflecting relative canine reduction in males and enlargement in females) and corresponding relatively narrower rostrum (measured across canines); genetically, with 3.7–6.7 % sequence divergence for cyt b from other populations.

Differs from P. t. kimberleyensis in the following ways: externally, with lusher fur and generally darker dorsal colouration, grey-based ventral fur, much narrower zone of contrasting pale fur on inside of fore- and hind-limbs, preauricular patch rarely developed, relatively longer tail with more extensive furring of the base and longer ‘brush’, much larger pinnae, inner metatarsal pad smoothly united with first interdigital pad; cranially, larger in all dimensions but with proportionally broader foramen magnum, relatively shallower rostrum and proportionally smaller molars; genetically, with 5.7–7.8 % sequence divergence for cyt b from other populations.

Differences from P. p i r at a are listed under the account of that taxon (see below).

Description of holotype. External measurements, as taken from label: HB 200, TL 221, Pes 29, Ear 29. Pes measured on puppet skin c. 42 mm.

The dorsal fur is relatively dense and lush, the contour hairs measuring 11–12 mm in the centre of the back. The overall colour of the back and flanks is grey with a silvery frosting, this effect imparted by a combination of narrow white tipping on grey-based contour hairs. Abundant black-tipped guard hairs are distributed evenly over the body and project as much as 7 mm through the fur. The mid-dorsal zone is distinctly darker than the flanks owing to a more intense basal pigmentation.

The abdomen has a narrow, off-white central zone made up of pale cream hairs with short grey bases. This zone expands anteriorly to cover the pectoral region, and posteriorly, to surround the scrotum. The boundary between flank and ventral colouration is diffuse. The fore- and hind-limbs are grey externally but with a narrow zone of contrasting off-white fur extending along the inner surface. The scrotum is pigmented and thinly clothed in off-white fur. A narrow, elongate gular gland is evident as a zone of pigmented skin measuring 4 mm by 22 mm of the lower throat. The location of this gland is not marked by any obvious external discolouration of the fur, but hairs in this region have a russet tinge basally.

The fur on the head is essentially pale grey on the sides of the face and dark grey with diffuse frosting on the crown. Additional facial patterning includes a well-developed, dark russet mid-rostral stripe, a broad and indistinct, dark grey loreal stripe and small, black postorbital spot, and distinct off-white orbital crescents. The vibrissal pads are thinly clothed in short grey fur. The mystacial vibrissal papillae are darkly pigmented and all facial vibrissae are thick and black to the tips. The pinnae are extremely large, weakly pigmented and sparsely furred internally except along their anterior and posterior borders, which carry a narrow strip of short black hairs. The external surface of the pinna is clothed in short dark hairs.

The basal portion of the tail is thickly furred on all sides, and supports numerous projecting guard hairs, continuing the colour and texture of the rump ( Fig. 6 ). This narrows gradually and gives way to a short tail ‘stem’ that is clothed above and below by long, adpressed hairs; these are white with short black tips on the upper surface and sides of the stem, but are rich russet on the under-surface, blending forward into the base of the brush. The tail ‘brush’ is lush and measures up to 170 mm; it consists of jet black hairs. The basal portion of the tail (cloaca to the base of the brush) measures 85 mm.

The upper surface of the pes supports a mixture of white, dark grey and russet hairs, giving it an overall grizzled appearance. This merges into white fur on the sides of the foot and around the heel. The digits are densely clothed in white hairs. The plantar surface of the pes is granular and supports a total of five conspicuously striated pads. The inner metatarsal and first interdigital pads are fused with no obvious line of demarcation; their combined length is 13.1 mm. The outer metatarsal pad measures 7.4 mm and is separated by a gap of 3.9 mm from the fourth interdigital pad. The second to fourth interdigital pads are elongate and of subequal length.

The cranium of WAM7674 is illustrated in Figure 19 . Measurements of the holotype and summary statistics for available specimens of both sexes are provided in Table 5. Male-biased sexual dimorphism is present in SL, ZW and PRW ( Table 6). The lower canines of males are only slightly larger on average than those of females ( Table 5; Fig. 13 ). Comparison with the nomino-typical race indicates that this is a consequence of a lesser degree of canine enlargement in males combined with a greater degree of enlargement in females. Other notable features of the cranium are the relatively great width of the foramen magnum in both sexes (a feature shared with South Australian and Victorian P. t. tapoatafa ) and the relatively large auditory bullae of females (also matched by females of the New South Wales and Queensland population of P. t. tapoatafa ) ( Table 5).

Observed variation. Adults attain body weights to 222g for males and to 166g for females (Rhind 2002). External measurements taken from museum specimen records are summarised in Table 4 . The ratio of average body weight for adult males and females, measured in each of two years, was 1.24 and 1.44 ( Rhind & Bradley 2002).

Females have six to eight teats in the pouch, with the following frequencies (6 teats: 46%; 7 teats: 18%; 8 teats: 39%; n = 82; data from Rhind et al. 2001:362; also Rhind 2002). Fur inside the pouch of adult females is gingery (e.g., WAM16027).

Ventral colouration varies somewhat among the material examined; some individuals (e.g., CM6810, WAM16027) have a broad off-white to cream zone on the abdomen and extensive cream fur on the inside of the limbs, while others have less extensive pale wash on the chest and throat (e.g., WAM2839, WAM5006). One specimen (WAM888) has poorly-developed cream-tipped preauricular patches; another (WAM 2839) lacks any darkening of the mid-dorsal fur.

The outer metatarsal pad is variable in length; the longest measured (WAM16027) is 9.1 mm, separated by 2.2 mm from the fourth interdigital pad. The pinnae on one specimen (WAM2839) are more heavily pigmented.

Taxonomic remarks. Rhind et al. (2001) identified some of the diagnostic cranial differences between southwestern and southeastern P. tapoatafa and recommended that they be recognised as distinct taxa. The same view was expressed by Spencer et al. (2001), based on the combined genetic and morphological evidence; however, their estimate of genetic divergence for cyt b was inflated, owing to a local sequence misalignment at position 322 ( Spencer et al. 2001: Fig.1 ).

Former and present distribution. Phascogale t. wambenger was recorded historically from a wide region of southwestern Western Australia, from Lake Hinds in the north, to Kalgan in the southeast ( Fig. 20 ). This broad distribution implies that the species once occupied a variety of different habitat types ranging from closed forest to open woodland. Surviving populations are largely restricted to forests dominated by jarrah ( Eucalyptus marginata ) ( Rhind 2004).

The Lake Hinds record and one from Nukarni represent significant inland outliers among the historical records. However, sub-fossil records indicate an even broader range in late prehistoric or early historic times, extending to the vicinity of Geraldton in the north and to the southern edge of the Nullarbor Plain in the east ( Lundelius & Turnbull 1973, 1978; Baynes 1987; see Fig. 20 & Table 9 ). These records raise the possibility that P. t. wambenger formerly occupied much of the West Australian ‘wheatbelt’ and was thus broadly sympatric with P. calura . Phascogale tapoatafa is not represented in more northerly sub-fossil localities in the Carnarvon Basin ( Baynes 2000) or on Cape Range Peninsula ( Baynes & Jones 1993).

On a more general note, these widely distributed historical and sub-fossil records also point to an early and catastrophic historical decline of this species across much of its range, perhaps leaving only the most resilient local populations to persist, albeit tenuously, through to the commencement of systematic faunal survey and collection during the early decades of the 20th century. In this regard, it is interesting to note Leake’s (1962: 51) statement that this species was often seen in the Kellerberrin district in the wheatbelt of Western Australia but, 'like other native animals, it disappeared in the nineties of the last [19th] century'.

Phascogale t. wambenger has been the focus of a major field study in the jarrah forest ( Rhind 1996, 1998, 2002, 2003, 2004; Rhind & Bradley 2002). Outside of this habitat, nothing is recorded of its natural history.

Figures

FIGURE 6. Ventral surface of the tail in representatives of four populations of the Phascogale tapoatafa group; a) nominotypical P. tapoatafa (CM 20990); b) P. t. pirata (CM 7225); c) P. taoatafa southwestern W. A. (WAM 5006, from Balingup Brook); d) P. tapoatafa Kimblerley, W. A. (WAM 16028, from Pago Mission).

FIGURE 13. Graph illustrating the geographic variation in Lower Canine Length (LCL) and the expression of sexual dimorphism for this character. Green bars = males; orange bars = females. Each bar represents the observed range and the black line represents the mean or sole values in case of populations 5 and 7. Population codes: 1: southwest Western Australia; 2: South Australia; 3: Victoria; 4: New South Wales and southeast Queensland; 5: northeast Queensland; 6: ‘ Top End’ of the Northern Territory; 7: Kimberley region of Western Australia.

FIGURE 19. Crania and dentaries of P. tapoatafa wambenger subsp. nov. a) WAM 7674, holotype, an adult male from Quindalup, Western Australia, and b) CM 3569, a subadult male from Boya, Western Australia. Each series consists of (left to right) dorsal view of cranium, ventral view of cranium, and lateral view of right dentary.

FIGURE 20. Map of southwest Western Australia, showing the historic (dark grey) distribution of P. tapoatafa wambenger subsp. nov., based on museum specimens and reliable sightings. The dot symbol represents an outlying historical record. Star symbols are sub-fossil records judged to be of late Holocene age.

FIGURE 1. A Brush-tailed Phascogale (Phascogale tapoatafa wambenger subsp. nov.) photographed in life (reproduced courtesy of J. & M. Lochman).