Suta gaikhorstorum, Maryan & Brennan & Hutchinson & Geidans, 2020

Maryan, Brad, Brennan, Ian G., Hutchinson, Mark N. & Geidans, Lukas S., 2020, What’s under the hood? Phylogeny and taxonomy of the snake genera Parasuta Worrell and Suta Worrell (Squamata: Elapidae), with a description of a new species from the Pilbara, Western Australia, Zootaxa 4778 (1), pp. 1-47 : 28-34

Suta gaikhorstorum sp. nov.

Pilbara Hooded Snake

( Fig. 14 )

Holotype. WAM R127817 , male, 5 km S of Mount Tom Price Mine , (22°47′49″S 117°47′20″E), Western Australia, Australia, collected by S. Anstee, 12 November 1997. Fixed in 10% formalin, stored in 70% ethanol, liver tissue stored in ultrafreezer ‒80°C at WAM.

Paratypes (8). All from Western Australia . WAM R 69680, male, 14 km SE of Minthicoondunna Spring , (22º49′S 118º21′E) ; WAM R 102161, male, 5.8 km NNW of Mount Windell , (22°36′08″S 118°31′15″E) ; WAM R 110946, female, 22.1 km WSW of Pannawonica , (21°41′38″S 116°07′04″E) ; WAM R116676 , male, 25 km ESE of Kooline Homestead , (22°47′28″S 116°32′46″E) ; WAM R135021 , male, Mount Whaleback , (23°20′15″S 119°41′48″E) ; WAM R141401 , female, Near Cape Preston , (20°03′50″S 116°09′47″E) ; WAM R145263 , female, 5 km S of Mount Tom Price Mine , (22°48′34″S 117°46′40″E) ; WAM R163133 , male, 8.2 km ENE of Urandy Bore , (22°24′35″S 116°23′32″E) .

Other material examined. A full list of material examined is provided at the end of the paper in the Appendix.

Diagnosis. A medium-sized, moderately robust species of Suta (total length to 460 mm, males mean 359 mm, females 352 mm) with: 15 midbody scale rows; 160‒168 ventrals; 23‒34 subcaudals; 164‒172 vertebrals; head moderately distinct from the neck; one or two secondary temporals; variable body colouration of light to rich reddish brown, brown or bright red; body scales often without dark pigment or with indistinct black base or blotch concealed by overlapping posterior edge of preceding scale and occasionally extending back as very fine edge on anterior facets or faint peppering; complete black hood on the head extending back on to first 4‒6, mostly 5 verte- brals on the nape; without pale markings in front of the eyes, and very minimal pale indents behind the eyes, mostly to midpoint level of the lower primary temporals.

Description of holotype ( Figs. 11B, E , 13 ). Measurements (in mm) and meristic values: ToL 438, SVL 395, TailL 43 (10%), HeadL 11.8, HeadW 9.1, HeadD 5.5, SnL 5.2, BW 9.9, BD 9.2, FrL 4.0, FrW 2.8, SupOcL 2.3, SupOcW 1.3, EyeW 1.8, VS 166, MBSR 15, AntSR 16, PostSR 13, ScS 31, VertSc 170, SupLab 6, InfLab 7.

Scalation and proportions as in the diagnosis for the genus and species. Individual characteristics include: internasals slightly wider than long, in broad contact with each other, in broad contact with rostral, nasals and prefrontals; prefrontals slightly wider than long, narrowing laterally, in full contact with internasals and frontal; one preocular, slightly wider than high, in broad contact with prefrontal and third supralabial, in broad contact with nasal on both sides; two postoculars, the lower higher than wide; two large primary temporals on both sides, the upper slightly wider than high and the lower projecting between fifth and sixth supralabial not contacting oral margin; two smaller secondary temporals on both sides, the upper slightly higher and above sixth supralabial; six supralabials, sixth much the largest, fifth slightly smaller; seven infralabials, sixth much the widest; five rows of intergulars between chin shields and anteriormost broad ventral.

After ≥ 20 years in preservative ( Fig. 13 ), the holotype is a dull brown on the dorsal surface with a complete darker brown hood on the head, and without pale markings in front of eyes, the dark hood extending back on to first four vertebrals ( Fig. 11B ). The indistinct dark base or blotch on the anterior facets, some body scales with faint peppering, is retained. Ventral surface under head, including most of supralabials, and along body is white with very minimal pale indents to midpoint level of lower primary temporals behind the eyes ( Fig. 11E ).

Colouration in life, preservative and variation. The following description of colouration in life is based on Figs. 14A, B, C and field observations of S. gaikhorstorum sp. nov. from the Pilbara region.

In life, variable body colouration of light to rich reddish brown ( Fig. 14A ), brown ( Fig. 14B ) or bright red ( Fig. 14C ), grading to lighter brown on the lower flanks in some individuals and without obvious dark pigment on body scales. Any pigment restricted to an indistinct dark grey to black base or blotch extending back as very fine edge on anterior facets or faint peppering. Complete dark grey, particularly anteriorly ( Fig. 14A ), to black hood on the head, extending laterally on to upper portion of the supralabials, particularly from third to sixth, and extending back on to the nape for 4‒6 vertebrals. Individuals with an overall brown appearance as shown in Fig. 14B appear to be more prevalent at lower elevations in the northwest Pilbara (B. Bush, pers. obs.). Eyes are black without discernible pupils. Ventral surface under the head, including most of the supralabials and along the body is white with glossy shine.

In preservative, body colour is similar to the holotype; some individuals (e.g. WAM R 110947) are slightly darker brown. The dark hood has faded to a light brown on one specimen ( WAM R145263 ). The white ventral surface remains glossy .

Variation includes: most specimens have an indistinct dark margin, at most a very fine edge on anterior facets of body scales, made discernible by using fine tweezers to lift the overlapping leading edge of preceding scale. Occasional individuals (e.g. WAM R 69680, WAM R 110946) have faint dark peppering on the body scales. There is no indication of pale markings on the dark hood in front of the eyes. In most specimens, the pale indents behind the eyes are very minimal as shown in Fig. 11E . In individuals (e.g. WAM R141401 ) without discernible indents behind the eyes, the lower primary temporals are entirely enclosed within the dark hood, while others (e.g. WAM R135021 ) have the pale indents at most to slightly over midpoint level of the lower primary temporals .

Variation in measurements and scalation. Table 7 presents the means, standard deviations and ranges of the characters measured and counted (as defined in Table 2) for each sex and all specimens of S. gaikhorstorum sp. nov. listed in the Appendix. Table 9 presents the individual measurements and meristic counts for the type series of S. gaikhorstorum sp. nov..

Adult total length in the larger sexed males of S. gaikhorstorum sp. nov. and S. monachus are similar, while female S. gaikhorstorum sp. nov. are noticeably larger than female S. monachus ( Table 7). This is contrary to Storr et al. (2002: 204) and Bush & Maryan (2011: 63) who mention the Pilbara population is larger by attaining 520 mm in total length. The largest male individuals measured for both species were equally 460 mm in total length on WAM R69680 of S. gaikhorstorum sp. nov. and WAM R163205 of S. monachus . The head measurements of S. gaikhorstorum sp. nov. show this species is proportionately larger, exceeding S. monachus in all parameters ( Tables 7, 8, Fig. 11B ).

As noted by Storr (1981: 507), all nine specimens from the Hamersley and Ophthalmia Ranges in the Pilbara region, and none from elsewhere, have 2 primary + 2 secondary temporals. To quantify this intraspecific variation, we examined a larger sample size of 37 WAM specimens (not listed) of S. gaikhorstorum sp. nov., recording the typical condition for S. monachus of 2 primary + 1 secondary temporals ( Fig. 11C ) in 17 specimens of S. gaikhorstorum sp. nov. on both sides and the condition of 2 primary + 2 secondary temporals in 13 specimens including the holotype WAM R127817 ( Fig. 11E ) on both sides. The remaining seven specimens have various opposing conditions that included 2 + 2 on the left side and 1 + 1 on the right side in WAM R62460. This variation is similar to that observed in S. monachus , although S. gaikhorstorum sp. nov. has a much higher frequency of possessing two secondary temporals that is rarely seen in S. monachus . Both the 2 + 1 and 2 + 2 temporal scale conditions in S. gaikhorstorum sp. nov. were dispersed throughout the Pilbara region and in some instances recorded from the same area (e.g. WAM R 110946 ‒47).

Apart from the temporals, other head scales in S. gaikhorstorum sp. nov. display minimal intraspecific variation. All the specimens have the nasal contacting the preocular, except in one specimen (WAM R62460) these scales are separated by the prefrontal on the right side. The first four anterior ventrals of one specimen (WAM R54474) are divided.

Compared to S. monachus , sexual dimorphism is similarly expressed, albeit comparatively less, with higher mean values and range for ToL, TailL and ScS in males ( Table 7). The mean ToL values in both sexes are noticeably closer; possibly suggesting it is less dimorphic. Males have on average slightly higher HeadL, HeadW, HeadD and SnL values. Males also have a noticeably higher BW range. The mean values and range of the two longitudinal scale counts VS and VertSc are very similar in both sexes ( Table 7). Results of the T-test data shows statistical significance only attained between sexes for ScS ( Table 8).

Etymology. We take pleasure in naming this species after passionate naturalists, wildlife educators and rehabilitators Klaas & Mieke Gaikhorst of the Armadale Reptile & Wildlife Centre, who have made an immense contribution to the public awareness of Australia’s natural heritage.

Distribution. Endemic to the arid Pilbara region of Western Australia ( Fig 12 ). Most collection records are from the Hamersley Range, a heavily dissected region of banded ironstone occupying the southern part of the Pilbara craton. Suta gaikhorstorum sp. nov. is widespread with collection records spanning a distance for over 400 km from east to Mount Whaleback near Newman (WAM R135021) northwest to the coast at Cape Preston (WAM R141401) and south to 25 km ESE of Kooline Homestead (WAM R116676).

Habitat. Suta gaikhorstorum sp. nov. occupies a variety of arid vegetation associations growing on heavy, often stony soils, including stony plains with Triodia ( Fig. 15 ), Mulga Acacia aneura woodlands, hard alluvial plains with scattered thickets of Mulga or open scrub, rocky hillcrests and slopes typically with Eucalyptus woodlands/ mixed shrublands over a Triodia -dominated understorey and drainage lines of Acacia and/or Eucalyptus over a tus- sock grass understorey, or the weed Buffel Grass Cenchrus ciliaris Linnaeus. During a series of biological surveys by Biologic Environmental Survey in the Hamersley Range, 16 of 23 records of S. gaikhorstorum sp. nov. were recorded from undulating stony plains with Triodia and Mulga woodlands (M. O’Connell, pers. comm.).

Regarding shelter sites, S. gaikhorstorum sp. nov. is presumably similar to S. monachus . Bush & Maryan (2011: 63) mention under rubbish, rocks and logs; inside Triodia clumps and down earth cracks. There is limited microhabitat information provided with the specimen data, apart from one specimen (WAM R116676) found under a log. A combination of biological surveys conducted by consultancy companies and field observations in the Pilbara region have caught S. gaikhorstorum sp. nov. in funnel or pit-traps, mainly buckets, and found them nocturnally active on sealed roads or tracks. Some degree of habitat partitioning occurs in the Pilbara region, where S. gaikhorstorum sp. nov. and S. fasciata generally prefer the woodlands and/or shrublands on heavy and stony soils and S. punctata the Triodia -dominated sandplains on light soils. In areas where S. punctata dominates on cracking clay plains (see Bush & Maryan 2011: 21), the other two species appear to be less prevalent (B. Bush, pers. obs.).

Close parapatry or sympatry with other species. Based on collection records the geographic distributions of S. gaikhorstorum sp. nov. and S. monachus appear to be parapatric ( Fig. 12 ). Currently the two species are known to occur within ~ 70 km of each other in the east: WAM R135021 of S. gaikhorstorum sp. nov. from Mount Whaleback versus WAM R42912 of S. monachus from Mundiwindi and a considerable distance of ˃ 350 km in the west: WAM R116676 of S. gaikhorstorum sp. nov. from 25 km ESE of Kooline Homestead versus WAM R 120607 of S. monachus from 33 km SSE of Carnarvon. A field observation of S. gaikhorstorum sp. nov. has been made in closer proximity to the Mundiwindi record within ~ 45 km in the Ophthalmia Range east of Newman (B. Bush, pers. obs.). The only recorded instance of sympatry involving S. gaikhorstorum sp. nov. is with S. fasciata and S. punctata (B. Maryan & B. Bush, pers. obs.).

Comparisons with other species. Diagnostic differences between S. gaikhorstorum sp. nov. and S. monachus are listed under the foregoing species account. Suta gaikhorstorum sp. nov. differs from S. fasciata and S. punctata with which it occurs in sympatry in: smaller adult total length to 460 mm (versus to 620 mm and 520 mm *, respectively) and dark hood on the head (versus blotched or spotted on the head). Differs further from S. fasciata in: 15 midbody scale rows (versus 17, rarely 19) and without obvious pattern on the body (versus distinctly cross-banded). *B. Bush has observed total lengths of 650 mm in S. fasciata and 610 mm in S. punctata .

Remarks. Bush & Maryan (2011: 63) illustrate S. gaikhorstorum sp. nov. including the same individual as shown in Fig. 14C . Seven other described snake species are endemic (or nearly so) to the Pilbara region: the blind snakes, Anilios ganei (Aplin) , A. longissimus (Aplin) and A. pilbarensis (Aplin & Donnellan) , a python, Liasis olivaceus barroni Smith and the elapids, Acanthophis wellsi Hoser , Demansia rufescens Storr and Vermicella snelli Storr ( Bush & Maryan 2011) . Biological surveys and field observations in the Pilbara region to date indicate S. gaikhorstorum sp. nov. to be secure and widespread, occurring in large areas set aside for the conservation of flora and fauna, such as Millstream-Chichester and Karijini National Parks.

Figures

FIGURE 11. Dorsal head views and extent of dark hood on the nape in (A) WAM R20606 of Suta monachus, and (B) WAM R127817 of Suta gaikhorstorum sp. nov., and lateral head views showing the outlined number of primary (P) and secondary (S) temporals in (C) WAM R172448 of Suta monachus with 2 + 1, (D) WAM R20606 of Suta monachus with 1 + 1, and (E) WAM R127817 of Suta gaikhorstorum sp. nov. with 2 + 2 (images‒B.Maryan).

FIGURE 12. Map of Australia showing distribution of Suta monachus (circles) and Suta gaikhorstorum sp. nov. (triangles). White symbols indicate specimens examined in DNA analysis.

FIGURE 13. Preserved holotype WAM R127817 of Suta gaikhorstorum sp. nov. (image‒B. Maryan).

FIGURE 14. Suta gaikhorstorum sp. nov. photographed in life from (A) 25 km W of Pannawonica, Western Australia, (B) 60 km S of Karratha, Western Australia, and (C) Hope Downs, Western Australia (images‒A, C: B. Maryan, B: B. Bush).

FIGURE 15. Representative habitat of Suta gaikhorstorum sp. nov., stony plain vegetated with dense Triodia and sparse Acacia at 22 km W of Pannawonica, Western Australia (image‒B. Bush).