Anilios leptosoma ( Robb, 1972 )

Vidal, Nicolas, 2017, Worms in the sand: Systematic revision of the Australian blindsnake Anilios leptosoma (Robb, 1972) species complex (Squamata: Scolecophidia: Typhlopidae) from the Geraldton Sandplain, with description of two new species, Zootaxa 4323 (1), pp. 1-24 : 9-12

Anilios leptosoma ( Robb, 1972)

Murchison Blindsnakes

Figures 3A–B , 4

Holotype. WAM R29623, an adult male collected from “ The Loop ”, lower Murchison River, 35 km north-east of Kalbarri (27°33'S; 114°28'E), Western Australia, in September 1967 by R.B. Humphries.

Paratype. WAM R29624, from ‘ The Loop’ , lower Murchison River, 35 km north-east of Kalbarri (27°33'S; 114°28'E) Western Australia, September 1967.

Diagnosis. A moderately long, slender Anilios to about 400 mm total length. Distinguished from all other Anilios by a combination of midbody scales in 16 rows, dorsal body scales 583–781, snout in profile prominent with obtusely angular horizontal edge, snout rounded and weakly trilobed in dorsal view, nasal cleft originating from second supralabial, extending anteriorly to nostril and terminating at rostral scale, presence of a terminal tail spine and lack of any black colouration on head, body or tail.

Description of holotype (WAM R29623). A slender male Anilios , measurements and counts: SVL 249.6 mm; TailL 8.5 mm (3.3% of SVL); BW 2.5 mm; MBSR 16; TDS 605; DBS 648; SCS 26; anal scales 4.

Head in dorsal view rounded and elongate, gradually widening posteriorly, not distinct from body; snout tapering anteriorly from posterior to eye to a distinctly narrowed but broadly rounded rostral protrusion anterior to rostral-nasal suture, faintly trilobed anterior to rostral-nasal suture; rostral extends anteriorly beyond anterior edge of nasal scales for ~one-quarter of rostral length; head bluntly angular in profile, evenly rounded dorsally to anteriormost point of rostral protrusion, hardened rostral edge extends anteriorly and ventrally slightly forming blunt protrusion, not hooked, ventral surface of snout from anterior rostral edge to lower jaw flat; rostral scale in dorsal view oval in shape, much longer than wide (~1.8 x 1.2 mm), widest at rostral-nasal suture, anterior protrusion from rostral-nasal suture shallowly concave giving faint trilobed appearance, posterior edge of rostral terminating anterior to level of eye, overlapping frontal and nasals; frontal wider than long, ~2 times the area of postfrontal, overlapping postfrontal and supraoculars; postfrontal wider than long, overlapping parietals; postfrontal and interparietal separated by parietals coming into contact between them; interparietal wider than long, similar in area to frontal, overlapping four unevenly sized body scales (including first of vertebral body scale row), one of which represents an aberrant asymmetrical scale not part of the regular body scale series presented by other specimens of the species; supraoculars larger than frontal, ~1.5–1.75 the size of frontal, overlapping postfrontal, parietal and ocular, narrowly separated by postfrontal scale, separation ~one-third of postfrontal width at widest point; parietals much wider than long, ~half the size of supraoculars, slightly wider than supraoculars, ~half the length of supraoculars, overlapping interparietal, one body scale and upper postocular; nasal scales ~2.0–2.5 times higher than wide, widest just dorsal to nostril, overlapping frontal, supraocular, preocular, first and second supralabials, narrowly separated by frontal, separation ~one-quarter frontal width at widest point, ~equal to width of supraocular separation; preoculars ~4 times higher than wide, ~one-quarter the size of nasal scale, overlapping supraocular, ocular, second and third supralabials; ocular scales higher than wide, ~3 times the size of preocular, shallowly wedged between third and fourth supralabials, widest near level of eye, overlapping parietal, two postoculars and fourth supralabial; postoculars two, slightly larger in size to body scales; eyes dark, small and inconspicuous, ~3–4 times the size of nostril, positioned under ocular and preocular scales, mostly in ocular and below sutures of preocular, supraocular and ocular scales; nostrils oblong in shape, anteriorly offset to middle of nasal scale, positioned ventrolaterally below dorsolateral narial prominences, much closer to rostral than preocular, distance from rostral-nasal suture ~one-half of nostril width, not visible from above; nasal cleft originates from anterodorsal edge of second supralabial, extending dorsally then anteriorly in a gradual curve to posteroventral edge of nostril, along ventral edge of nostril, from anteroventral edge of nostril dorsally and anteriorly to reach rostral scale, not visible from above; supralabials four, first smallest and overlapped by nasal, second ~4 times the size of the first, overlapped by nasal and preocular, third ~3 times the size of second, overlapped by preocular and overlapping ocular, fourth largest, ~3.0–3.5 times the size of third, overlapped by ocular, posterior edge terminates just posterior to posteriormost edge of ocular scale; supralabial imbrication pattern type T-III sensu Wallach (1993); mental scale about 1.5 times wider than long; postmental wider than long, slightly larger than mental; scale organs sparsely over rostral and nasals, becoming more sparsely distributed over scales posteriorly.

Body width constant between head and tail; body scales smooth, lacking texture, imbricate, ~2.0–2.5 times wider than long, posterior edge overlapping anterior edge of proceeding scale; tail width tapering gradually from cloaca for length of tail, tapering more abruptly posteriorly to blunt rounded tip, terminating in short (<1 mm) blunt apical spine; apical spine surrounded at base by six scales.

Colouration. Colour in preservative pale cream-tan, anterior half slightly darker than posterior half, colouration of tail consistent with posterior half of SVL.

Variation. Table 1 presents ranges for meristic characters of all specimens examined. SVL up to 391 mm; TailL 1.2–4.0% of SVL, mean 2.0% (N = 24); TDS 598–798, mean 670 (N = 23); BDS 583–78, mean 652 (N = 23); SCS 13–29, mean 19 (N = 29); MBSR 16 (N = 29).

Head in dorsal view rounded, faintly trilobed in most specimens (N = 23), occasionally more prominently trilobed (N = 5, R26012, R66343, R136311, R142023 and R146455). Head shape in lateral view bluntly angular with hardened anterior rostral edge. Hardened rostral edge protruding downwards slightly (N = 24), not as well developed or absent on small individuals (<150 mm SVL).

Rostral oval in shape, much longer than wide, ~1.5–2.0 times longer than wide, posterior edge of scale terminates level with eyes (N = 19) or anterior to them (N = 9). Frontal scale usually larger than postfrontal (N = 24), rarely equal (N = 1). Frontal often 2.5 times larger than postfrontal (N = 13), sometimes 2 times (N = 5) or 3 times (N = 4), rarely 5 times (N = 1) or 1.5 times (N = 1) the size of postfrontal. Frontal often equal to interparietal in area (N =16), sometimes 1.5 times larger (N = 4) or smaller than, ~0.75 times the size of interparietal (N = 5). Scale size and position could not accurately be determined for some specimens due to damage or missing scales (N = 3). Nasal scales narrowly to widely separated by frontal, distance between nasals approximately one-third (N = 9), one-quarter (N = 6) or two-fifths (N = 6) the width of frontal scale, occasionally one-fifth (N = 1), half (N = 1) or entire width of frontal (N = 1), rarely in contact (N = 1). Supraoculars narrow to widely separated (N = 22), sometimes in contact (N = 3); separation between supraoculars approximately one-third (N = 8), half (N = 6), onefifth (N = 3), two-fifths (N = 3) or one-quarter (N = 2) of postfrontal width. Parietal scales narrowly to widely separated (N = 23), sometimes in contact (N = 2); separation between parietals approximately one-fifth (N = 8), one-sixth (N = 6), two-fifths (N = 5), one-third (N = 3), one-quarter (N =2) or half (N = 1) the width of interparietal scale. Eye positioned below ocular, preocular and supraocular (N = 15) or preocular and ocular (N = 11) scale sutures, occasionally below preocular and nasal scale suture (N = 2).

There are no known images of the species in life; the description below is based on preserved specimens. Colouration pale cream to tan with dorsum slightly darker than ventrum (N = 12), uniform colouration (N = 10) or with anterior portion of body slightly darker than posterior portion and tail (N = 7). Variation of colouration does not correspond with geographic distribution. The four smallest specimens (R13462, R55038, R55039 and R 113009, 125– 144 mm SVL) have uniform colouration; however, the remaining larger specimens vary in colouration in the following ways. A) uniform pale colouration (N = 12), anterior portion darker, gradually becoming lighter posteriorly, lightest on tail (N = 8), C) dorsum darker, gradually becoming lighter ventrally, lightest on ventrum (N = 6).

Sexual dimorphism is not obvious, although male SCS count and TailL in relation to SVL (%) are higher than in females: male SCS 22–29, mean 26, TailL 2.6–4.2% of SVL, mean 3.5% (N = 7); female SCS 13–18, mean 16, TailL 1.3–2.4%, mean 1.8% (N = 21).

Comparison with other species. Anilios leptosoma can be distinguished from all but three Anilios species ( A. longissimus , A. minimus and A. nema ) by its slender elongate body and low MBSR counts (16 vs 18, 20, 22 or 24) which does not differ within any species of the genus. Of the remaining three Anilios species with 16 MBSR ( A. longissimus , A. minimus and A. nema ), A. leptosoma can be distinguished by the termination point of nasal cleft at rostral completely dividing the nasal scale (vs terminating at nostril in A. longissimus and A. minimus , or midway between nostril and rostral in A. nema ), higher number of dorsal body scale rows (583–781 vs 381–457 in A. minimus and 520–589 in A. nema ) and a less depressed head in comparison to A. longissimus .

Within its distribution, A. leptosoma is most similar in general appearance to A. systenos sp. nov., A. obtusifrons sp. nov. and A. grypus ; however, it is easily diagnosed by the low MBSR (16 vs 18 in A. systenos sp.

nov., A. obtusifrons sp. nov. and A. grypus ) and a combination of absence of a hooked beak (vs distinct hook in A. grypus ), termination point of the nasal cleft at the rostral scale (midway between nostril and rostral in A. obtusifrons sp. nov.) and absence of any black pigment on the head or tail (vs black pigment on head and/or tail in A. grypus ).

Distribution. Anilios leptosoma is known from the mid-west of Western Australia from 7.5 km south of Northampton (WAM R13642 & R 113007), north to Wooramel, approximately 114 km south-east of Carnarvon (WAM R55038 & R55039), and from the west coast to Meeberrie Station, approximately 200 km east north-east of Kalbarri (WAM R51097) in the east ( Fig. 1 ). Based on the extent of specimen records and using The International Union for Conservation of Nature (IUCN) Red List Guidelines ( IUCN Standards and Petitions Subcommittee 2017), a rough calculation of the species’ extent of occurrence (EOO) is approximately 32,000 km 2 of which its area of occupancy (AOO) is likely to be much smaller. No limiting factors that may restrict the species distribution have been identified.

Habitat and ecology. Collector’s notes associated with specimens indicated specimens were collected from habitats supporting loose sands or loam substrates of various colour. One specimen was collected in open mallee woodland with Banksia ashbyi to 5 m with a canopy cover of less than 10% over Spinifex longifolius and mixed small to medium shrubs to 1.5 m with cover ranging from 30–70%, from soil below a clump of spinifex (R66343). One specimen was collected from amongst the roots of spinifex in a burnt eucalypt woodland on red soil (R57545) and another was found in a mallee woodland with low Acacia on yellowish-brown sand. Specimens from Binnu were raked from red sandy loam spoil heaps in Acacia and Casuarina shrubland (R146454–56, R146459). Two specimens (R55038 and R55039) were collected from under a cement slab at Wooramel homestead garden.

Etymology. Derived from the Greek words leptos meaning fine or thin and soma meaning body in reference to the thin thread-like appearance of the species. The amendment to the specific epithet to A. ‘leptosomus’ by McDiarmid et al. (1999) and subsequently accepted by other authors ( Hedges et al. 2014; Pyron & Wallach 2014; Wallach et al. 2014) is not warranted ( Shea 2015). As Robb (1972) did not state explicitly the use of the word ‘ soma ’ as a noun or adjective, it is to be treated as a noun and does not change from A. leptosoma with the resurrection of Anilios by Hedges et al. (2014).

Remarks. There are insufficient data to assess A. leptosoma under IUCN Red List assessment criteria A and C–E; however, confirmed records of the species allow partial assessment under criterion B. The EOO for A. leptosoma is approximately 32,000 km 2 which exceeds values for any threatened categories and its area of occupancy (based on 29 confirmed records) equals 60 km 2 which partially meets criterion B2 for endangered; however, due to the lack of any population data, threats or potential decline for the species it cannot be assessed any further under criterion B. Despite the limited number of confirmed specimens, the species has been recorded from habitats that are relatively widespread across most of its EOO and the AOO is therefore considered to be underestimated. Due to the limited knowledge of the species, particularly in regards to its population/s and any major threats or evidence of decline, A. leptosoma is considered to be Least Concern under the IUCN Red List assessment criteria.

The line drawings of the head scalation for A. leptosoma in the original description by Robb (1972) are presumably based on the paratype specimen (R29624) which shows closer affinities with the scale configuration illustrated than the holotype.

Anilios systenos sp. nov. Ellis & Doughty

Figures

FIGURE 1. Distribution of the Anilios leptosoma species complex in Western Australia. Localities marked with an asterik (*) denote localities for specimens used in molecular analysis by Marin et al. (2013 a).

FIGURE 3. Line drawings showing snout morphology and head scalation variation within the Anilios leptosoma complex in dorsal and lateral view. A – B) A. leptosoma holotype (WAM R 29623); C – D) A. systenos sp. nov. holotype (WAM R 114892); E – F) A. obtusifrons sp. nov. holotype (WAM R 146400). Irregularity of some head scale sutures and edges illustrated represent scale damage and scratches of holotype specimens.

FIGURE 4. Anilios leptosoma (Robb, 1972) holotype (WAM R 29623). Scale bar = 10 mm.