Pseudonaja affinis, GUNTHER, 1872

Skinner, Adam, 2009, A multivariate morphometric analysis and systematic review of Pseudonaja (Serpentes, Elapidae, Hydrophiinae), Zoological Journal of the Linnean Society 155 (1), pp. 171-197 : 187

PSEUDONAJA AFFINIS GÜNTHER, 1872

Pseudonaja affinis Günther, 1872: 35 . Holotype, BMNH 1946.1.19.77; type locality, Australia.

Demansia nuchalis tanneri Worrell, 1961: 56 . Holotype, NMV D9819 ; type locality, Boxer Island , Recherche Archipelago, Western Austalia.

Pseudonaja affinis exilis Storr, 1989: 421 . Holotype, WAM R19870; type locality, Rottnest Island , Western Australia.

Diagnosis: Pseudonaja affinis may be distinguished from the remaining species of Pseudonaja redescribed here in exhibiting either a dark grey or brown throat, contrasting with a lighter ventral ground colour, or (less commonly) an entirely dark brown venter. (A contrasting dark grey throat is very occasionally observed in P. inframacula specimens from Yorke Peninsula, however, these are separable from P. affinis specimens geographically. A dark grey throat may also be present in the ‘Orange with black head’ colour form of P. mengdeni , although this is always associated with an entirely dark brown or black head and neck.) Specimens from Western Australia can be differentiated from specimens of P. mengdeni (also P. aspidorhyncha , P. inframacula , P. nuchalis and P. textilis , which are not distributed in southern Western Australia) in possessing 19 (as opposed to 17) dorsal rows at midbody; however, specimens from South Australia nearly invariably exhibit 17 dorsal rows at midbody. Pseudonaja affinis differs from the remaining species of Pseudonaja except P. aspidorhyncha and possibly P. mengdeni (see Skinner et al., 2005, and below) in displaying a diploid chromosome number of 34, and typically exhibits a greater number of ventrals than P. inframacula and P. nuchalis .

Description: Ventrals 204–226; subcaudals 51–63; snout appears rounded from dorsal perspective; nasal undivided (65 of 66 cases) or partially divided (one case), contacting preocular; two (52 of 66 cases) or three (14 cases) postoculars; parietal contacting (56 of 66 cases) or separated from (10 cases) lower postocular (or mid postocular where three postoculars are present); six supralabials; seven (64 of 66 cases) or eight (two cases) infralabials; temporals 1 + 2 + 3 (56 of 64 cases), 1 + 2 + 4 (five cases) or 1 + 2 + 5 (three cases); 5–8 nuchals contacting parietals; dorsals in 20–26 rows at first ventral, 17–20 rows one head length posterior to occiput, 17–19 rows midbody, 13–15 rows one head length anterior to vent, 14–18 rows at last ventral; anal divided (28 of 33 cases) or undivided (five cases); snout–vent length 396– 1299 mm; tail length 69–226 mm, 15.411 –20.257 % of snout–vent length.

Dorsum pale to dark brown, greyish brown or olive brown; numerous dark brown or black scales often scattered or composing irregular blotches on body; indistinct pattern of darker, oblique bands, 1–3 dorsals wide, occasionally discernible (especially laterally and posteriorly), rarely accompanied by a fine, dark brown or black reticulated pattern; many specimens exhibit an indistinct, broad, darker brown or greyish brown band on neck; dark blotches often present on head; venter medium to dark brown, or dirty cream or pale yellow, often with subtle darker brown or greyish brown spots or blotches; ventrals occasionally exhibit a lighter brown or grey (rarely darker brown) sectorial marking laterally; posterior margins of ventrals of some specimens darker brown; nearly all specimens possess a contrasting dark grey or brown throat; chin commonly cream; buccal epithelium whitish to pale grey (preserved specimens); iris dark with pale yellowish grey to orange ring around pupil.

Mengden (1985) reported a diploid chromosome number of 34, with a gradual decrease in the size of autosome pairs 4–16, and sex chromosomes that differ notably in size.

Distribution: Southern Western Australia and South Australia, from Perth to Whyalla, eastern Eyre Peninsula ( Fig. 10 ). Note that the distribution of P. affinis extends considerably further east than indicated by previous authors (e.g. Cogger, 2000; Wilson & Swan, 2003).

Notes: Although I have not examined the holotype of P. affinis, Günther (1872: 35) reported that ‘This snake is readily distinguished from P. nuchalis by a greater number of scales, which are arranged in nineteen series’ (italics in original), while his Plate IV, Figure C indicates that the holotype has seven infralabials. This combination of character states differentiates P. affinis specimens from other species of Pseudonaja , confirming that the holotype is part of the lineage identified here.

Figures

Figure 10. Geographical distribution of Pseudonaja affinis specimens examined in this study (closed circles) and/or included in Skinner et al.’s (2005) phylogenetic analysis (open circles represent specimens not included in the morphometric analyses). Codes for geographical groups correspond with those in Table 2.