Lerista miopus ( Günther, 1867 )

Edwards, Danielle L., 2017, Taxonomy of the Sand Sliders of Western Australia’s central coast (genus Lerista, Squamata: Scincidae): recognition of Lerista miopus (Günther, 1867), Zootaxa 4317 (1), pp. 111-133 : 123-127

Lerista miopus ( Günther, 1867)

Figs. 7 and 8

Synonyms

Soridia miopus Günther, 1867

Lygosoma bipes concolor Werner, 1910 Lygosoma (Rhodona) nigriceps Glauert, 1962

Holotype. From Champion Bay, Western Australia. Reported to be lodged at the British Museum of Natural History , London, but actual whereabouts unknown ( Cogger et al. 1983).

Neotype (designated herein). WAMR136122 , Strickland St , Geraldton, Western Australia (28° 46' S 114° 37' E), collected 1 Oct. 1998. See Fig. 7 .

Diagnosis. A species of Lerista with forelimb either absent (represented by a depression) or a nubbin (<0.7% SVL), one or two digits on a relatively short hindlimb (<14% SVL), fused frontoparietals, four or five supraciliaries and a free eyelid (vs. fused into a transparent spectacle).

Comparisons. Only three other species of Lerista , L. connivens , L. lineopunctulata and L. varia , have the combination of forelimb a nubbin or stump, two clawed digits on the hindlimb, free eyelid and interparietal fused to the frontoparietals. From L. connivens , L. miopus differs in a reduced hindlimb (6–14% SVL vs. 13–23%, 3–10 lamellae beneath longest toe vs. 11–14, 2–7 supradigitals above longest toe vs. 8–11, 63–89 scales between adpressed limbs vs. 50–60), more supraciliaries (five vs. four) and colour pattern (brown-grey dorsally with or without indistinct dark brown spots, pattern fading laterally vs. a broad, dark brown vertebral zone with 2 lines of dark brown spots and a thick, dark brown upper lateral band). From L. lineopunctulata , it differs in a reduced forelimb (usually a depression only or a nubbin no more than 0.7% SVL vs. a stump 0.7–1.2% SVL) and less distinct colour pattern (indistinct lines or reticulations vs. lines of dark brown spots dorsally). From L. varia , it differs in a reduced hindlimb (6–14% SVL vs. 13–24%, 2–7 supradigitals above largest digit vs. 8–10, 63–89 scales between limbs when adpressed vs. 43–61) and more paravertebrals (73–97 vs. 63–73).

Description of neotype WAMR136122. SVL = 86 mm, HL = 8 mm (9% SVL), HW = 6 mm (60% HL), SE = 1 mm (17% HL), eyelid free, EE = 4 mm (45% HL), ear minute, SA = 18 mm (21% SVL), AG = 64 mm (74% SVL), MW = 7 mm (8% SVL), L1 a depression only, L2 = 9 mm (11% SVL), TL = 36 mm (42% SVL, regrown). Hindlimb with a single clawed toe.

Midbody scale rows 20, NC = 27%, NaL = 33%, FN = 63%, three supraoculars, five (right side) or six supraciliaries (left side), first supraciliary contacts preocular, loreal, prefrontal, first supraocular and second supraciliary; frontal contacts interparietal, first and second supraoculars, prefrontal and frontonasal; frontoparietals fused to interparietal, IW = 116%, two loreals, prefrontal contacts both loreals, frontonasal, frontal, first supraocular and first supraciliary, two preoculars, single presubocular, six palpebrals, single postocular, single postsubocular, six supralabials, fourth supralabial entering eye, two postsupralabials, six infralabials, two infralabials contacting postmental, four scales between last infralabial and ear, single pretemporal, temporal contacts fifth and sixth supralabials, postocular, pretemporal, parietal, second temporal and postsupralabial; PL = 75%, three rows of enlarged chin shields, four nuchals, 83 paravertebrals, MV = 72%, two enlarged preanals, hindlimb digit damaged (tip missing on both sides) so no measurements taken, 51 subcaudals (but tail regrown).

Colour pattern (in preservative). Pale grey with very indistinct dark brown spots. Dark edging on head scales almost absent. Belly and throat immaculate cream. Limbs brown above, cream to yellow below. Tail similar pattern to the body but with heavy dark brown flecking.

Variation. Sample size is 33 unless otherwise noted: SVL = 43–106 mm (83 ± 14 mm), HL = 8–14% SVL (10 ± 1%), HW = 26–70% HL (59 ± 11%), SE = 13–26% HL (21 ± 3%), eyelid free, EE = 43–57% HL (50 ± 3%), ear minute, SA = 18–27% SVL (22 ± 2%), AG = 68–80% SVL (75 ± 3%), MW = 7–11% SVL (8 ± 1%), L1 a depression (n = 16) or nubbin (n = 17) up to 0.7% SVL (0.2 ± 0.2%), L2 = 6–14% SVL (9 ± 2%), TL = 87–91% SVL (89 ± 1%, n = 6). Hindlimb with a single (n = 58) or two (n = 88) clawed toes.

Midbody scale rows 18–22 (mode = 20), NC = 9–41% (24 ± 7%), NaL = 21–36% (27 ± 4%), FN = 51–69% (60 ± 4%), three supraoculars, usually five (n = 25), sometimes four (n = 8) supraciliaries, first supraciliary contacts preocular, loreal, prefrontal, first supraocular and second supraciliary (sometimes contacts frontal, n = 7); frontal contacts interparietal, first and second supraoculars, prefrontal and frontonasal; frontoparietals fused to interparietal, IW = 92–133% (118 ± 9%), two loreals, prefrontal contacts both loreals, frontonasal, frontal, first supraocular and first supraciliary, single (n = 7) or two (n = 25) preoculars, single presubocular, 5–7 palpebrals (mode = 6), single postocular (rarely two, n = 2), single postsubocular, six supralabials, fourth supralabial entering eye, two postsupralabials, six infralabials, two infralabials contacting postmental, 4–6 scales between last infralabial and ear (mode = 4), single pretemporal, temporal contacts fifth and sixth supralabials, postocular, pretemporal, parietal, second temporal and postsupralabial (sometimes fails to contact postocular, n = 3, sometimes fails to contact parietal, n = 9); PL = 57–79% (64 ± 5%), three rows of enlarged chin shields, 2–6 nuchals (mode = 4), 73–97 paravertebrals (mode = 82), MV = 57–95% (72 ± 9%), two enlarged preanals, 63–89 body scales between limbs when adpressed (mode = 70), hindlimb 11–20 body scales in length (mode = 13), 3–10 subdigital lamellae under the longest toe (mode = 8), 2–7 supradigitals (mode = 6), 73–83 subcaudals (average = 74, n = 3).

Colour pattern. Brown to grey, usually with very indistinct lines of black spots. Often spots are so indistinct as to appear patternless, while some individuals (3 of 31 examined), were as boldly marked as L. lineopunctulata s.s. These three individuals were collected well within the range of L. miopus and otherwise conformed well morphologically. Head with black edging and markings. Labial scales white with black edging. Belly and throat immaculate whitish. Limbs brown above, whitish below. Tail similar pattern to the body but the pattern is heavier, although less distinct and there is often a yellowish wash. Colour pattern in preservative little different except that the black markings tend to fade to dark brown and overall colour becomes browner with length of time in preservative.

Distribution. Coast and coastal islands of Western Australia, from Point Murat (21° 47' S) to north-east of Jurien Bay (30° 15' S). See Fig. 1 . One specimen is considerably further east of all other records at Walyahmoming Rock (WARM98752; 30° 40' S 118° 45' E), although there is reason to doubt the accuracy of this record (P. Doughty pers. comm.).

Sympatry with Lerista lineopunctulata . The distribution of L. miopus and L. lineopunctulata appear to be very close to each other, with specimens assigned morphologically to L. miopus only 8 km from L. lineopunctulata specimens at Jurien Bay. Specimens from this area can be assigned confidently to either taxa but genetic information for them was lacking. A closer study of this apparently near contact between the two could be rewarding.

Reproduction. Sex was determined in 36 specimens opportunistically, either through observation of everted hemipenes or previous dissection. There were ten females and 26 males in this sample. The smallest sexually mature male measured 60 mm SVL, the smallest female 63 mm. The largest specimen measured (106 mm SVL) was male, the largest female 97 mm. No consistent differences between the sexes were observed in any morphological character measured.

Data on the reproductive cycle that could be opportunistically collected without further dissection are presented in Table 3. In summary, reproductive individuals were found in spring, not summer or autumn. One female in late vitellogenesis had a developing clutch of four follicles. A gravid female had ova measuring 5.33 mm diameter, but the date of collection of this individual is unknown.

In both species, two toes on the hindlimb was the more common condition than a single toe, although the singletoed condition occurred more frequently in L. miopus (40% vs. 10% in L. lineopunctulata s.s.). In both species, single-toed specimens were geographically proximate to each other, in a situation perhaps analogous to L. kalumburu , where a geographically-defined population of two-toed individuals was found to be conspecific with surrounding three-toed populations ( Amey & Worthington Wilmer 2014). In L. miopus , they were found in coastal habitats, whereas in L. lineopunctulata s.s., they were only found in two suburbs of Perth, City Beach and Trigg Beach. The significance of this coastal affinity is unknown, as is the functional significance of differing toe arrangements (although see Benesch & Withers 2002). Once again, the inadvisability of relying on the single morphological character of limb arrangement in Lerista for making taxonomic judgements is illustrated ( Amey & Worthington Wilmer 2014).

We show that L. lineopunctulata is more closely related to the short-range endemics L. connivens and L. varia found in the vicinity of Shark Bay, each of which are also sympatric with L. miopus ( Fig. 1 ). The dynamic history of the Western Australian coast has long been invoked to explain the high levels of diversity along the southwest coasts. Glacio-eustatic fluctuations in sea levels, beginning in the early Pleistocene through to the present, resulted in the recession of the Indian Ocean that exposed vast areas of coastal sands, expanding coastal habitats along southern Western Australia during glacial maxima ( Dodson 2001; Hocking et al. 1987). During interglacial periods, coastal habitats contracted to resemble current distributions. For reptiles, complex diversity patterns are most extreme in the many Lerista species found in the mid-western coast which display extreme levels of incipient species, with multiple short range endemics such as L. lineopunctulata and L. miopus . Sea level change ( He et al. 2013) and high levels of soil diversity ( Edwards et al. 2012) have both been implicated as factors explaining genetic divergence in Lerista species in this system, but limited evidence exists to explain broader patterns of diversification in this genus beyond their morphological labiality ( Skinner 2010), which may vary considerably within species ( Amey & Worthington Wilmer 2014). The limited dispersal abilities, specific soil requirements, and highly adapted morphologies displayed by Lerista species may make them predisposed to diversification, explaining the high levels of diversity seen in particularly dynamic habitats such as the south-western Australian west coast.

Figures

FIGURE 1. Map showing collection localities for Lerista lineopunctulata, L. miopus, L. connivens and L. varia.

FIGURE 7. WAMR 136122, neotype of Lerista miopus (Günther, 1867). A. Whole specimen; B. Lateral head view; C. Dorsal head view. Photo by P. Waddington.

FIGURE 8. Lerista miopus in life. Specimen from Tamala Stn, Western Australia, not vouchered, identified using Storr et al. (1981). Photo by S. Wilson.