Delma vescolineata, Mahony & Cutajar & Rowley, 2022

Mahony, Stephen V., Cutajar, Timothy & Rowley, Jodi J. L., 2022, A new species of Delma Gray 1831 (Squamata: Pygopodidae) from the Hunter Valley and Liverpool Plains of New South Wales, Zootaxa 5162 (5), pp. 541-556 : 549-553

Delma vescolineata sp. nov.

Holotype. AMS R.185998, male, Muswellbrook (-32.2°, 150.9°), New South Wales, collected by S. Mahony and R. Seeto 10 November 2018.

Paratypes. AMS R.185999, male, collection details as for holotype; AMS R.186619, female, Jerrys Plains (- 32.4°, 150.8°), New South Wales, collected by A. Dudley 25 November 2018 .

Other material examined. AMS R.175738 male, from Pine Ridge, Windy Station (-31.6°, 150.4°), New South Wales collected by P. Spark is assigned to this species on the basis of morphology. AMS R.98656 from Bulga, (- 32.6°, 151.0°), New South Wales collected by S. Donellan is consistent with D. vescolineata sp. nov. in possessing a fused internasal to post-nasal contact and two internasal scales. This specimen is tentatively assigned as D. vescolineata sp. nov., however, as it is a juvenile, it is recommended that genetic material from this locality be collected and assessed. It was not included in morphological analysis or description because of its tentative placement.

Diagnosis. A small–moderate sized Delma (SVL 71–101mm) distinguished from all congeners, except D. impar , by a combination of: internasal scales typically fused to postnasal and first supralabial; two internasals; two precloacals; midbody scales in 14 rows; 65–71 ventral scale number (male mean 65.67, female 71); and typical presence of an obscure pale body stripe along the upper lateral zone. Delma vescolineata sp. nov. is diagnosed from D. impar and all other members of the D. molleri species group genetically, by 29 diagnostic nucleotide sites in the ND2 gene ( Table 2 ).

Description of holotype. Measurements (in mm) and meristic values: SVL 71, TL 185, MSR 14, HD 3.09, HL 4.95, HW 3.81, ML 7.41, RH 1.17, RW 1.91, EW 1.38, SL 3.72, HLS 8, VE 65.

Form. Head short and narrowing to rounded snout both in dorsal and in lateral view, slightly wider than body posteriorly; obvious tympanic aperture, indicated by horizontal elliptic opening posterior to corner of mouth; body relatively elongate, cylindrical, as round as high and of subequal width along entire length; hindlimbs begin immediately above the vent, are adpressed to the body; tail more than twice (242%) the body length, thick at the base and tapering gradually to a fine tip.

Head. Head scales smooth, non-imbricate and heterogenous in size; rostral with obtuse apex penetrating between internasals; one pair of internasals in broad contact and smoothly fused with both the first supralabial and the postnasal scale; nostril positioned at anterior margin of postnasal with a cleft running posteriorly dividing the postnasal and first supralabial; prefrontals symmetrical and in broad contact; a small granular scale present at the convergence point of the internasals and prefrontals; supraloreal twice as high as wide and contacting three loreal scales; seven loreals on the left and eight loreals on the right, the anterior two slightly longer; four supraciliaries, first and fourth sub-equal, third the smallest, second twice as wide as first and fourth; two subequal supraoculars; two frontals, the posterior larger and penetrating between the parietals; two parietals, the one on the left slightly larger; occipital present; two upper temporals in broad contact posterior to the occipital; six supralabials, third the widest and positioned below the eye; five infralabials on the left with the third the longest, four infralabials on the right with third and fourth longest, on both sides the fourth extends in broad contact underneath the third; mental wider than long. General form of head and details of scalation illustrated in Fig. 3 .

Body. Body scales smooth, homogenous and arranged in parallel longitudinal rows with 14 at midbody; ventral body scales transversely enlarged; pre-cloacal scales two.

Colour. In life, the occiput is dark brown. Labial scales white with darkened flecks on the third and fourth supralabials and corresponding infralabials. Tympanum surrounded by three darkened flecks, with two on dorsal margin and one on the ventral margin. Colouration becomes cream–yellow posterior to the tympanum, graduating to a light brown anterior lateral zone with subtleties of salmon. Dominant dorsal colouration of the body and tail is light brown, merging into a slightly paler lateral zone. Ventral colouration pearlescent white. An obscure pale stripe extends from the beginning of the trunk to near the tail tip, becoming broken along the tail. This stripe occurs along the margin of the fourth and fifth midbody scale rows and is bordered by scattered dark flecks.

Comparison with similar species. Delma vescolineata sp. nov. and D. impar are unique among congeners in possessing a combination of: internasal scales typically fused to postnasal and first supralabial; two internasals; two pre-cloacals; and typical presence of an obscure pale body stripe along the upper lateral zone. Comparison of appearance in life between D. vescolineata sp. nov. and its sister taxon D. impar along with parapatric congeners D. plebeia and D. inornata is made in Fig. 4 .

Delma vescolineata sp.nov. is morphologically similar to D.impar and as such,identification may prove difficult in specimens with insufficient locality data,despite no known sympatry of the two taxa. Delma vescolineata sp.nov. can be identified from D. impar and its two parapatric congeners ( D. plebeia and D. inornata ) by comparison of the following features: Delma vescolineata sp. nov. — dark markings scattered on the labials, particularly the infralabials and with a dark smudge or spot on the supralabial immediately posterior eye (the fourth supralabial in all examined material); scattered dark flecks on the lateral forebody and around ear; typically the third supralabial below the eye; typically 14 midbody scale rows. Delma impar — typically no dark markings on supralabials, when present relatively continuous below and anterior to the eye, absent from the supralabial immediately posterior the eye; typical absence of dark patterning on lateral forebody and posterior of head; typically fourth supralabial below eye; typically 15 midbody scale rows. Delma plebeia — dark markings scattered on the labials, particularly the infralabials and with a dark smudge or spot on the supralabial immediately below the eye; scattered dark flecks on the lateral forebody and around ear; typically the fourth supralabial below the eye; typically 16 midbody scale rows. Delma inornate — typically no dark markings on supralabials, when present typically forms a stripe along upper margin of supralabials; typical absence of dark patterning on lateral forebody and posterior of head; typically fourth supralabial below eye; typically 16 midbody scale rows.

Variation. All specimens examined were consistent in possessing 14 midbody scale rows, two precloacal scales, and the third supralabial scale below the eye. Bilateral asymmetry in labial scale counts was present in all four specimens. Supralabial asymmetry was noted in seven on the left (AMS R.175738 and AMS R.185999), and six on the right in all individuals. Additionally, for infralabial scale counts, four were present on the left (AMS R.185998 and AMS R. 186619) with five on both sides in all other individuals. Furthermore, one specimen (AMS R.175738) had only a partially fused first supralabial and internasal junction on the right side.

Delma vescolineata sp. nov. is likely to exhibit further variation in meristic features outside of those seen within the low sample size available here. Its sister taxon, D. impar , exhibits morphological variability across its distribution and it is feasible that this is similar in D. vescolineata sp. nov.. For example, changes in the number of midbody scale rows to 13 or 15; presence of the fourth supralabial scale below the eye; or the lack of fusion between the internasal and either supralabial or postnasal scales.

Colouration in life. Top of head dark grey to light brown and uniform or with darker streaks or stippling. Labials, adjacent ear opening and lateral area of forebody with scattered dark spots, bars or smudges, most consistently present on supralabial four, posterior to the eye. Lateral area posterior to ear opening may be slightly rusty–yellow tinged. Rest of body and tail, light brown, often with several dark flecks on dorsolateral scales. Usually, a faded or obscure pale line starts posterior to the ear running along the body on the junction of scale row four and five. In some individuals this line is more distinct and may be accompanied by a second pale line between other laterodorsal scale rows. Ventral surface under head and along body white with no patterning. One juvenile observed had a darker head tending towards black, extending onto the nape and lateral forebody, the rest of their body and tail is brown and lacks pattern.

Etymology. The specific epithet, “ vescolineata ”, is derived from the Latin adjective ‘vescus’ meaning weak, poor, thin or little and the Latin adjective ‘lineata’ meaning lined. This is in reference to the weak and obscure pale lines of this species in comparison to the usually bolder pale lines of its sister taxon D. impar .

Distribution and sympatry. Delma vescolineata sp. nov. is distributed from the Hunter Valley region to the Liverpool Plains region of NSW ( Fig. 5 ). Delma vescolineata sp. nov. is known from four separate sites, three less than 25 km separate within the Hunter Valley, and a fourth from the Liverpool Plains. Two of these sites (Muswellbrook and Jerrys Plains) are represented by specimen and genetic data, while the third (Ravensworth) is represented by a genetic sample only. The fourth locality record assigned to D. vescolineata sp. nov. on the basis of morphology is a specimen (AMS R.175738) from the Liverpool Plains approximately 80 km west north-west from the Muswellbrook populations. There is additional tentative evidence of the species occurrence at Bulga with the presence of a juvenile specimen most similar to this species. It is probable that D. vescolineata sp. nov. is distributed more widely in both the Hunter Valley and the Liverpool Plains.

Within the Hunter Valley region, close parapatry exists between D. vescolineata sp. nov. and D. plebeia , as evidenced by genetic sampling confirming their proximity to within 2 km. In comparing the respective distributions of these taxa, contact is likely within the Hunter Valley; however D. plebeia appears to favour grassy woodlands, whilst D. vescolineata sp. nov. has been recorded in more open secondary grasslands. It is possible that these species contact in habitat ecotones, but we found no evidence of genetic exchange between the taxa and no indication of morphological intermediacy.

Sympatry between D. vescolineata sp. nov. and its grassland-dwelling congeners, D. inornata and D. plebeia , is likely within the Liverpool Plains region. The latter species’ distribution continues south, where it also occurs in broad sympatry with D. impar .

Habitat. The four locations of D. vescolineata sp. nov. are within secondary native grassland ( Benson 1996) in association with sparse box-gum or ironbark woodland. The primary canopy species consists of yellow-box ( Eucalyptus melliodora ) and narrow-leaved ironbark ( E. crebra ), with a diverse ground cover layer containing multiple grasses including Austrostipa sp. , Bothriochloa sp. , and Chloris sp. At least one site is on primarily basaltic soils with scattered surface rocks. At this site D. vescolineata sp. nov. has been located while sheltering beneath discarded rubbish (building rubble, metal, organic waste, mattresses) as well as the scattered surface rock. The ground cover of this site is heavily disturbed and is primarily composed of non-native pasture grasses such as Avena fatua and Bromus sp. , and also features other exotic plants such as the tiger pear ( Opuntia aurantiaca ). Additional sites used for agricultural purposes are heavily disturbed by livestock and contain no natural surface refugia; however, D. vescolineata sp. nov. has been detected beneath dried fecal material of cattle. Specimens, including the holotype, were collected active on a paved road that intersected suitable grassland habitat. These specimens were located active by day, similar to other Delma spp. , indicating diurnal activity periods.

Remarks. The geographic distribution and population abundance of D. vescolineata sp. nov. is unknown, but the core sightings and specimens are within the upper Hunter Valley within a triangle formed by Muswellbrook, Jerrys Plains and Ravensworth. Within this area, additional to specimens and data presented here, there are 35 observation records in the Atlas of Living Australia identified as D. impar , with 23 of these observed in 2018 ( Atlas of Living Australia, accessed 08/Aug/2021). Our comparison of specimens previously assigned to D. impar from the Hunter Valley region concluded all were D. vescolineata sp. nov., with no evidence of true D. impar present in the region. We therefore recommend these records now be changed to D. vescolineata sp. nov., to avoid future confusion in the range of D. impar . Large areas of the Hunter Valley and Liverpool Plains regions have been cleared for agriculture or mining ( Benson & Redpath 1997; Bombell & Montoya 2014; Hunter 2016). No natural or derived grassland is protected in any parks or reserves within the probable distribution of D. vescolineata sp. nov.

Figures

FIGURE 3. Holotype (AMS R.185998) of Delma vescolineata sp. nov., A) in life, B) lateral view of head, C) dorsal view of head, D) labelled lateral scale illustration of head, E) labelled dorsal scale illustration of head. R = rostral, IN = internasal, SL = supralabials, IL = infralabials, PN = postnasal, L = loreal, FN = frontonasal, PF = prefrontal, SC = supraciliary, SO = supraocular, RF = rostral frontal, CF = caudal frontal, PT = pretemporal, P = parietal, T = temporal, O = occipital.

FIGURE 4. Photos in life of Delma vescolineata sp. nov. (A–D), Delma impar (E–F), Delma plebeia (G), Delma inornata (H); A) AMS R.186619, Jerrys Plains NSW, B) AMS R.185999, Muswellbrook NSW, C) Not collected, Muswellbrook NSW, D) Not collected, Juvenile, Muswellbrook NSW, E) Not collected, Cooma NSW, F) Not collected, Naracoorte SA, G) Not collected, Muswellbrook NSW, H) Not collected, Canberra ACT.

FIGURE 5. Distribution of samples analyzed for morphological (A) or molecular (B and C) comparisons this study.