Phascogale tapoatafa kimberleyensis Aplin & Rhind

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 : 38-40

Phascogale tapoatafa kimberleyensis Aplin & Rhind subsp. nov.

Holotype: WAM 16028. Adult male. Pago Mission, Napier Bay, near Broome, Western Australia, 14 0 8’ S 126 0 43’ E. Collected by Gerald F. Hill, 19th February 1910. Puppet skin and skull .

Paratype: WAM 16029. Subadult male. Locality and collector as for holotype. Collected on 20th October 1909. Puppet skin and skull .

Etymology. Referring to the geographic region of occurrence of this taxon.

Diagnosis. A small-bodied race of P. tapoatafa that differs from the typical race of southeastern Australia in the following ways: externally, with shorter, crisper and generally paler dorsal fur, more extensive cream fur on venter, relatively shorter tail, more boldly patterned face with contrasting cream muzzle and cheek, inner metatarsal pad contacting but clearly distinct from first interdigital pad, probable lower number of teats; cranially, very similar to the other subspecies of P. tapoatafa but smaller in all cranial dimensions for both sexes and with proportionally narrower foramen magnum, relatively deeper rostrum and proportionally larger molars; genetically, with 3.0–5.8 % sequence divergence for cyt b from other populations.

Additional differences from P. t. wambenger and P. pirat a are listed under the accounts of those taxa.

Description of holotype. External measurements, taken from label: Total length 350, Ear 30; as measured on puppet skin: HB c. 200, TL c. 205, Pes c. 35.

The dorsal fur is relatively short and crisp, the contour hairs measuring 5–6 mm in the centre of the back. Overall colour of the back and flanks is pale grey with a silvery frosting. Abundant and evenly distributed blacktipped guard hairs project up to 7 mm beyond the contour hairs. The ventral fur is a uniform cream from the vent to the chin. A diffuse, yellowish patch on the throat overlies a pigmented gular gland that measures 25 mm long by 6 mm wide. The boundary between flank and ventral colouration is relatively sharp. The fore- and hind-limbs are grey externally and cream internally, with a sharp demarcation, especially on the hindlimb. The scrotum is lightly pigmented and thinly clothed in cream fur.

The face is boldly patterned with a russet mid-rostral stripe that merges posteriorly into a dark grey patch on the crown, a cream preauricular patch, a dark loreal stripe, a dark postorbital spot, and distinct, black-rimmed orbital crescents. The cream fur of the chin and throat merges with a cream supralabial bar that extends partway along the upper lip, while the cheek patch is cream peppered with black. The vibrissal pads are thinly clothed in short cream fur, peppered with black. The mystacial vibrissae are thick and black, some with short gingery tipping, but the papillae are unpigmented. The pinnae are moderately large and thinly furred except along the anterior margin which supports a fringe of short black hairs.

The tail supports a black ‘brush’ measuring 135 mm. The basal portion of the tail is only moderately furred, producing the effect of an elongate ‘stem’ (c. 67 mm). The dorsal fur of the stem is grey near the base, blending distally into off-white. The under-surface is grey blending into russet at the base of the brush.

The upper surface of the pes is grey with a silvery frosting, changing abruptly to white on the sides and on the digits. The plantar surface of the pes is granular and supports six conspicuously striated, raised pads. The inner metatarsal and first interdigital pads are in contact but with an obvious line of demarcation; their combined length is 12.6 mm. The outer metatarsal pad measures 6.7 mm and is separated by a gap of 2.7 mm from the fourth interdigital pad. The second to fourth interdigital pads are elongate and of nearly equal length.

The cranium of WAM16028 is illustrated in Figure 21 . Measurements are provided in Table 5. Too few specimens are available to demonstrate sexual dimorphism. However, the two adult males differ from the one adult female in ways that suggest male-biased dimorphism of the kind noted in the nomino-typical population—the male skulls are broader and more robust for their length, and have canines enlarged relative to near equal-sized cheekteeth.

Observed variation. External measurements taken from museum specimen records are summarised in Table 4 . The paratype, a subadult male, has softer, lusher fur of a more even grey colour. The tail ‘stem’ is proportionally shorter (35 mm vs 116 mm for brush). WAM1309, an adult female from Kunmunya Hill, has a well developed pouch with sparse, pale gingery hairs but the number of teats cannot be determined. The dorsal fur of this specimen is overall more gingery than the holotype or paratype but this is probably due to fading. The ventral fur is cream to the roots along a mid-ventral zone, from the chin to around the pouch. This is flanked on each side by a band of grey-based and cream tipped fur that extends onto the inside of the fore- and hind-limbs. The preauricular patch is more distinct in this specimen. The tail ‘stem’ is proportionally shorter again, measuring 35 mm vs 125 mm for brush). WAM53763, a damaged roadkill specimen, is an adult female with a damaged pouch; the number of teats cannot be determined. The pes measures 34 mm and the tail 207 mm with a basal stem of 55 mm. The outer metatarsal tubercle in this specimen is very short (4.7 mm; gap to fourth interdigital pad 3.5mm) and the second interdigital pad is slightly longer than the third and fourth. The combined inner metatarsal tubercle and first interdigital pad are smoothly united on the left pes but distinguished by a clear kink on the left pes. Rhind et al. (2001) reported a female specimen from Mitchell Plateau (WAM27208; as KIM5) with six teats; it is not known whether this represents the typical teat number.

Taxonomic remarks. This population has attracted little previous attention, although Troughton (1967: 32) remarked that “the Northern Australian race ( Phascogale tapoatafa pirata ) … is also found in the Kimberley division, Western Australia”. Rhind et al. (2001) also allied this population with P. t. pirata based on the small body size, slight brownish tinge to the dorsal fur and extensive cream venters. A total of five museum specimens are known from the entire Kimberley region (see Supplementary Table II for details).

Former and present distribution. The few records of this taxon are scattered throughout the Kimberley region, from Yampi Sound in the west to near Kalumburu (Pago Mission) in the east ( Fig. 22 ). There are recent records from Kimbolton Station near Derby (2003; WAM53763) and from the King Leopold Range (2001; sighting by Mr Murray Ellis, pers. comm.). Undated subfossil occurrences in the southwest Kimberley are reported by Start et al. (2012).

Figures

FIGURE 21. Cranium and dentary of WAM 16028, the holotype of P. tapoatafa kimberleyensis subsp. nov., an adult male from Pago Mission, Western Australia: a) dorsal view of cranium, b) ventral view of cranium, and c) lateral view of right dentary.

FIGURE 22. Map of northern Australia, showing the distributions of P. tapoatafa kimberleyensis subsp. nov (circles) and P. pirata (triangles). The square symbol represents the location of a sight record that might pertain to either P. pirata or P. tapoatafa.