Acanthophis cryptamydros, Maddock, Simon T., Ellis, Ryan J., Doughty, Paul, Smith, Lawrence A. & Wüster, Wolfgang, 2015

Maddock, Simon T., Ellis, Ryan J., Doughty, Paul, Smith, Lawrence A. & Wüster, Wolfgang, 2015, A new species of death adder (Acanthophis: Serpentes: Elapidae) from north-western Australia, Zootaxa 4007 (3), pp. 301-326 : 308-315

Acanthophis cryptamydros sp. nov.

Kimberley death adders Figs. 5–8

Holotype. WAM R174083, medium-sized male collected 1 km north-west of Theda Station homestead, Western Australia (14°46'59.10"S, 126°29'22.02"E), on 8 March 2014 by R. Ellis, G. Bourke, and R. Barrett. Fixed in 10% formalin, stored in 70% ethanol at WAM. Liver samples stored in 100% ethanol at WAM and SAM.

Paratypes. WAM R70690, sub-adult male, 45 km north-northeast Halls Creek, WA (17°51'00"S, 127°50'00"E); WAM R81245, adult male, Packsaddle Springs, near Kununurra, WA (15°54'00"S, 128°41'00"E); WAM R103755, adult male, Surveyors Pool, Mitchell River National Park, WA (14°39'46"S, 125°44'34"E); WAM R165567, adult male, Koolan Island, WA (16°08'04"S, 123°45'05"E); WAM R168918, adult female, Boongaree Island, WA (15°4'39.36"S, 125°11'13.56"E); WAM R172034, adult female, north-west Molema Island, WA (16°14'17"S, 123°49'49"E).

Diagnosis. A moderately stout Acanthophis to 645 mm total length. Distinguished from all other Australian Acanthophis by a combination of midbody scales in 22 or 23 rows, 125–139 ventrals, undivided prefrontal scales, posterior edge of frontal scale not extending beyond posterior edge of supraoculars, laterally flared supraoculars, area of lower secondary temporal scale equal to or smaller than sixth supralabial, anterior dorsal scales with prominent keels, and ventrum unpigmented except for 1–3 rows of spots on ventrolateral edge.

Description of holotype (WAM R174083). A medium-sized male Acanthophis , measurements and counts: ToL 482 mm; SVL 394 mm; TailL 88 mm (22% of SVL); HeadL 24.9 mm; HeadW 17.4 mm; MBSR 23; AntSR 20; PostSR 17; VS 129; ScST 54; SupLab 6; InfLab 7.

From above, head pear-shaped and distinct from neck, widest at interparietal scale angling forward to rostral and back to posterior jaw edge, narrowing to body; tip of snout blunt, broadly rounded; head in profile deepest at interparietal scale, snout convex; top of snout slightly concave where rostral and internasals converge; head scales rugose; rostral scale twice as wide as high, apex rounded, distal edges with low straight sides, ventral edge concave above lingual fossa; nasal scales narrowly separated by two internasals, approximately twice as wide as tall, rugose; nostril centered on nasal scale, opening dorsally and posteriorly, a shallow divot posterior to nostril; internasals as wide as long, in broad contact with each other, narrow contact with rostral, broad contact with nasals and prefrontals; prefrontals 1.5 times long as wide, narrowing laterally, 0.75 times area of frontal, 1.5 times area of internasals; frontal scale roughly rectangular, anterior edge slightly wider than posterior edge, approximately 1.5 times as long as wide (FrL 4.7 mm, FrW 3.0 mm), apex of posterior edge not extending beyond posterior edge of supraoculars; two parietals, as wide as long, anterior edge in contact with posterior angles of frontal, anterior edge of parietal sharing border with posterior edge of frontal, anterolateral edge in broad contact with supraocular, narrow contact with upper postocular, posterior border irregularly scalloped; preocular single, supraocular single, postoculars two, suboculars two; preocular in contact with prefrontal, nasal, third supralabial and anterior subocular scales; supraocular much longer than wide (SupOcL 5.03 mm, SupOcW 2.90 mm), thicker and rugose in appearance to other head scales, angled upwards at 30º; primary temporal scales two, lower primary temporal 2.5 times larger than upper, upper primary temporal feebly keeled; secondary temporal scales four, gradually increasing in size from dorsalmost to ventralmost, first and second with moderate keels, third and fourth smooth, fourth secondary temporal larger than prior three, located in the notch formed by fifth and sixth supralabials, two times smaller than sixth supralabial; supralabials six, sixth largest, fifth slightly smaller; first supralabial in contact with rostral and nasal, second in contact with nasal; third in contact with nasal, preocular, primary subocular, secondary subocular; fourth in contact with secondary subocular and lower postocular; fifth in contact with lower subocular, second primary temporal, fourth secondary temporal and sixth supralabial; mental triangular; infralabials seven, fourth infralabial largest, first in contact with postmental scale; anterior chin shields in contact with infralabials one to four; posterior chin shields in contact with fourth infralabial only, anterior and posterior chin shields forming a butterfly-like shape; six rows of intergulars between chin shields and anteriormost ventral.

Body width widest at midbody tapering gradually forward to base of head and posteriorly to cloaca; scale rows 23 at midbody (i.e., at 64th ventral scale from anterior), decreasing to 20 behind the head, 17 anterior to vent; 129 ventral scales; anal scale single; 54 subcaudal scales, first subcaudal paired, anteriormost 29 single, followed by 29 paired; scales on side of body diamond-shaped, scales in vertebral zone more narrow; dorsal keeling strongest on anterior quarter of body, 10–12 longitudinal scale rows wide; keeling weak along remainder of length; dorsolateral and lateral scales weakly keeled to smooth, ventral scales smooth ( Figs. 5–7 ).

Tail elongate, TailL 88 mm (22% of SVL), tapering from cloaca to laterally compressed caudal lure; ScST 54 (ScSS 30, ScSP 24). Caudal lure much higher than wide ending with terminal tail spine.

Eyes small with vertically elliptic pupil, iris mottled in appearance, similar in coloration to surrounding ocular scales.

Coloration. In life, ground color of dorsal and lateral surfaces pale orange-brown; 33 darker cross-bands ( Fig. 5 ); cross-bands two to four midbody scales wide with dark brown border; dorsal scales edged with black anteriorly; tail coloration same as dorsum with 12 bands; tail tip and terminal spine black with white to cream flecks; first midbody scale dark in center, distal edge pale; ventral scales cream-white and lacking pigmentation other than lateralmost edges; ventral coloration of tail similar in appearance to ventrum with patches of dark pigment in center of posteriormost subcaudal scales prior to black tail tip and terminal spine; supralabials stippled with black, stronger stippling on posterior labials, ventral edge pale white; infralabials pale white with dark oblong vertical blotch in center of scale, on posterior scales the ventral edge of the blotch is angled posteriorly.

In preservative, dorsal ground color dull orange brown; overall pattern is subdued with less contrast between light and dark cross-bands ( Fig. 6 ).

Variation. SVL up to 555 mm; TailL 15–24% of SVL, mean 20% (N = 22). FrW 47–73% of FrL, mean 59% (N = 26). Apex of posterior edge terminates equal to (N = 13) or prior to (N = 13) posterior supraocular edge, never post. Fourth secondary temporal equal to (N = 13) or smaller than (N = 13) sixth supralabial. MBSR 22–23 (N = 24), mostly 23 (N = 21), occasionally 22 (N = 3). AntSR 16–23, mean 19 (N = 24), PostSR 16–19, mean 18 (N = 24). Ventral scales 125–139, mean 130 (N = 23). First anterior subcaudal scale usually divided, not separated (N = 9), occasionally undivided (N = 5), divided and separated by two (N = 4), three (N = 3) or one (N = 1) by a small rounded scale. ScST 46–56, mean 50, ScSP 20–40, mean 30 and ScSS 14–32, mean 21 (N = 22).

Ground color of dorsal and lateral surfaces variable from dull red-orange, tan-brown or gray in coloration with darker cross bands ( Fig 6 ). Dorsal cross bands 44–61, mean 50 (N = 23); SVL 35–46, mean 39, Tail 9–15, mean 11 (N = 23). Tail tip black with white ventral surface, occasional small white lateral flecks (80%, N = 16), less often white (15%, N = 3) or banded (5%, N = 1). Ventral scales cream-white and lacking pigmentation other than lateralmost edges of ventral scale. Supralabials pale white, mottled in appearance fusing to darker markings on adjacent scales, lower edge of supralabials pale. Infralabials white-edged with dark pigment, both solid and mottled in appearance in center of scale extending to upper edge of scale.

Sexual dimorphism is not obvious, although female TailL % of SVL is shorter than males: female TailL 15– 19% of SVL, mean 18 (N = 10); male TailL 21–24% SVL, mean 22% (N = 10). The tail tapers much more abruptly posterior to the vent in females, whereas in males the tail tapers gradually. The number of ventral and subcaudal scales is similar in both sexes ( Table 3).

Distribution. Acanthophis cryptamydros sp. nov. is known from the Kimberley region of Western Australia. The species’ range in Western Australia is known to extend from Wotjulum (WAM R11241) in the west, 45 km north-north-east of Halls Creek in the south (WAM R70690), and Kununurra in the east (WAM R137470). Acanthophis cryptamydros sp. nov. is also known to occur on some offshore islands including Koolan, Bigge, Boongaree, Wulalam, and an unnamed island in Talbot Bay ( Palmer et al. 2013).

A single specimen (NTM R29109) with incomplete data (no collection date or precise latitude and longitude) is reported as occurring from Adelaide River in the Northern Territory ( Fig. 1 ); however, this locality may be in error. Further collecting from the area may resolve the issue.

Habitat and ecology. The holotype (WAM R174083) was collected early morning towards the end of the ‘wet season’ (early March) from among basalt boulders in savannah woodland at the edge of a low plateau near a small sandstone outcrop. Vegetation among the basalt boulder habitat was dominated by Eucalyptus tectifica and Corymbia greeniana amongst mixed shrubs over mixed groundcovers and annual/perennial grasses ( Fig. 9 ). Shrub cover was dominated by Grevillea mimosoides , Grewia retusifolia , Indigofera sp. and Olearia arguta ( Fig. 9 ). The specimen was observed retreating to grass tussocks after being disturbed. The specimen was tightly coiled within the grass tussock before attempting to move to another tussock when disturbed. WAM R145216 was collected from thick grasses on a creek bank subjected to minor sheet flooding at Little Mertens Falls. Collection notes and accession data of other specimens describe individuals collected from among grasses or leaf litter in sandstone habitats. One specimen was collected from under a rock in a vine thicket near a beach on an unnamed island in Talbot Bay (WAM R172034), and another from leaf litter in Acacia woodland on Wulalam Island (WAM R172035). Two specimens were collected from roads or tracks (WAM R70690, WAM R165567).

Examination of the stomach contents of two specimens revealed a mixture of frogs, lizards, and mammals. A juvenile specimen (WAM R1251B) had an adult Heteronotia species (aff. H. binoei ). In the gut of an adult specimen (WAM R141552), a subadult Lophognathus species ( L. gilberti ), an adult Litoria species (aff. L. nasuta or L. watjulumensis ), and hair belonging to a native murid species, Pseudomys sp. (aff. P. johnstoni or P. delicatulus ) were found. Two small reptilian eggs were also collected from the adult, possibly from the Lophognathus ingested. Accession data for WAM R116934 identified a Ctenotus pantherinus (WAM R117001) from examination of its stomach contents. An ecological study of Australian and Papuan death adders by Shine et al. (2014) included five specimens of A. cryptamydros ; however, examination of stomach contents revealed no prey items, only a small quantity of dirt. Examination of the gut contents of other northern Acanthophis species indicated a diet consisting of a wide range of vertebrate species, especially lizards but also including frogs, mammals, and some birds (Shine et al. 2014).

Examination of reproductive organs of an adult female specimen (WAM R106033) revealed 13 well-developed follicles approximately 10 x 14 mm in size (month of collection unknown).

Comparison with other species. Distinguished from A. pyrrhus by higher average MBSR (23 vs. 21), fewer ventral scales (125–139 vs. 136–158), pigment on lateral periphery of ventral scales (vs. no pigment on ventral scales), presence of pigment patches on infralabials (infralabials unpigmented in A. pyrrhus ), less prominent dorsal keeling (strongly keeled in A. pyrrhus , tapering to a sharp point on posterior edge), head scales less rugose, posterior edge of frontal scale not extending beyond posterior edge of supraoculars (equal to or beyond in A. pyrrhus ), and undivided pair of prefrontal scales (divided in A. pyrrhus ).

A. cryptamydros sp. nov. A. ' rugosus group'

Character N = 23 N = 14

(9♂, 7♀) (9♂, 5♀)

SVL 428±57 (322–555) N = 20 486±97 (375–690)

♂♂ N = 9 ♀♀ N = 7 ♂♂ N = 9 ♀♀ N = 5 412±41 468±54 434±57 581±82 (374–496) (392–555) (375–530) (482–690)

TailL 86±9 (72–110) N = 20 94±11 (80–110)

♂♂ N = 9 ♀♀ N = 7 ♂♂ N = 9 ♀♀ N = 5 90.6±9 81.4±5 92±11 98±9 (79–110) (76–89) (79–110) (85–108)

TailL/SVL 0.20±0.03 (0.15–0.24) N = 20 0.20±0.03 (0.15–0.23)

♂♂ N = 9 ♀♀ N = 7 ♂♂ N = 9 ♀♀ N = 5 0.22±0.01 0.18±0.01 0.21±0.01 0.17±0.03 (0.21–0.24) (0.15–0.19) (0.20–0.23) (0.15–0.22)

HeadL 26.1±2.4 (22.7–32.0) N = 20 31.1±5.5 (25.5–42.3)

HeadW 16.4±2.2 (13.8–20.2) N = 20 19.4±4.6 (13.1–27.1)

HeadW/HeadL 0.63±0.05 (0.54–0.71) N = 20 0.60±0.04 (0.51–0.66)

VS 130±4 (125–139) N = 20 127±4 (123–136)

ScST 50±3 (46–56) N = 20 46±6.14 (29–55)

♂♂ N = 9 ♀♀ N = 7 ♂♂ N = 9 ♀♀ N = 5 53±2 49±2 47±7 45±3 (51–56) (46–51) (29–55) (42–49)

MBSR 22.9±0.3 (22–23) 22.0 ±0.9 (21–23)

AntSR 19.2±1.3 (16–23) 20.3±0.6 (19–21)

PostSR 17.8±0.9 (16–19) 18.0±0.7 (17–19)

PreOc 1.0±0 (1) 1.1±0.3 (1–2)

SupOc 1.0±0 (1) 1.1±0.3 (1–2)

PostOc 2.0±0.2 (2–3) 2.1±0.3 (2–3)

SubOc 2.2±0.4 (2–3) 2.7±0.5 (2–3)

Ptemp 2±0 (2) 2.0±0 (2)

Stemp 4.4±0.5 (4–5) 4.0±0.4 (3–5)

SupLab 6.0±0 (6) 6.0±0 (6)

InfLab 7.0±0 (7) 7.1±0.3 (7–8)

FrL 5.6±0.5 (4.7–6.7) N = 20 7.2±0.9 (6.0–9.0)

FrW 3.3±0.3 (2.6–4.1) N = 20 3.4±0.5 (2.8–4.4)

FrW/FrL 0.59±0.06 (0.47–0.73) N = 20 0.48±0.02 (0.45–0.52)

SupOcL 5.5±0.5 (4.8–6.4) N = 20 6.4±0.7 (5.2–7.4)

SupOcW 3.1±0.3 (2.8–3.7) N = 20 3.7±0.5 (3.0–4.6) Differs from A. wellsi by higher midbody scale rows (22–23 vs. 19–21), less prominent dorsal keeling, posterior edge of frontal scale not extending beyond posterior edge of supraoculars (equal to or beyond in A. wellsi ), and more laterally flared supraocular (absent or less prominent in A. wellsi ). Differs from melanistic forms of A. wellsi by the absence of prominent black coloration on head and black dorsal bands.

Distinguished from A. antarcticus by higher average MBSR (23 vs. 21), more ventral scales (125+ vs. 124-), and more prominent anterior dorsal keeling (vs. smooth or very weakly keeled in A. antarcticus ).

Most similar to A. rugosus group in appearance, but differs through higher average ventral scale counts (130 vs. 127), despite considerable overlap in range, lacking dark pigment on the ventrum other than lateral edge (vs. distinct blotching of dark pigment), posterior edge of frontal scale not extending beyond posterior edge of supraoculars (beyond in 13 of 14 specimens, equal in one specimen) and size of lower secondary temporal not larger than sixth supralabial in area ( A. cryptamydros equal in 13 specimens, smaller in 13 vs. A. rugosus equal in 10, larger in 4). See Table 3 for further details.

Comparisons of A. cryptamydros sp nov. to the A. rugosus group are complicated by the likely existence of a number of undescribed species within the latter, which greatly increases variation within this complex. We comment on morphological characters that are useful in distinguishing these two taxa.

Etymology. The specific epithet is modified from the Greek words kryptos (cryptic, hidden) and amydros (indistinct, dim) in reference to the cryptic nature of the species and its indistinct appearance relative to its surroundings making its presence unknown to predators and prey. Used as a noun in apposition.

Remarks. The A. rugosus group is likely to contain a number of undescribed species. Taxonomic resolution of this group will further define differences between individual species within the group and A. cryptamydros sp. nov. The discovery of A. cryptamydros sp. nov. as a previously undescribed major lineage within Acanthophis highlights the incompleteness of our understanding of phylogenetic structure and species limits within the genus. At the same time, it also highlights the importance of the Kimberley region of Western Australia as a center of endemism (Doughty 2011; Oliver et al. 2012; Pepper & Keogh 2014).

Lethal ingestion of the cane toad ( Rhinella marina ) has been documented in previous studies on Acanthophis specimens from the Kimberley region and Northern Territory ( Phillips & Shine 2007; Hagman et al. 2009; Phillips et al. 2010; Pearson et al. 2014) indicating the species is likely to be at risk of significant decline as cane toads continue to move west across the Kimberley region. A detailed assessment on potential threats to the species including cane toads will identify the need for listing as a species requiring protection under state or federal legislation.

Figures

FIGURE 1. Distribution of Acanthophis sampled in northwest Australia. Only samples with accurate collection coordinates have been included, except specimen NTM R 29109 (star; see text). Colored circles correspond to sampled specimens: red = A. cryptamydros sp. nov.; blue = A. rugosus; turquoise = A. pyrrhus; green = A. wellsi. The collection locality of the holotype of A. cryptamydros (WAM R 174083) is displayed as a red diamond.

FIGURE 5. Acanthophis cryptamydros sp. nov. holotype (WAM R 174083) in life (photograph—R. J. Ellis).

FIGURE 6. Acanthophis cryptamydros sp. nov. holotype (WAM R 174083) showing dorsal and ventral coloration and pattern.

FIGURE 7. Head scalation and patterning of Acanthophis cryptamydros sp. nov. holotype (WAM R 174083).

FIGURE 8. Variation in Acanthophis cryptamydros sp. nov. WAM R 174083 (holotype), NTM R 29109 and WAM R 172034 (paratype).

FIGURE 9. Type locality habitat of Acanthophis cryptamydros sp. nov. in Theda Station, Kimberley region, Western Australia (photograph—R. J. Ellis).