Diporiphora jugularis (Macleay, 1877)

MELVILLE, JANE, DATE, KATIE SMITH, HORNER, PAUL & Doughty, Paul, 2019, Taxonomic revision of dragon lizards in the genus Diporiphora (Reptilia: Agamidae) from the Australian monsoonal tropics, Memoirs of Museum Victoria 78, pp. 23-55 : 32-33

Diporiphora jugularis (Macleay, 1877)

Common name. Black-throated two-pored dragon.

Figure 7 , Tables 3, 4

Grammatophora jugularis Macleay, W. 1877 . The lizards of the Chevert Expedition. Second paper. Proceedings of the Linnean Society of New South Wales 2: 97–104 [1878 on title page] [104]. Type data: syntype (s) – AMS R40672–4 , Cape Grenville, Cape York Peninsula, Queensland.

Diporiphora brevicauda De Vis, C.W. 1884 . On new species of Australian lizards. Proceedings of the Royal Society of Queensland 1: 97–100 [99]. Type data: holotype – whereabouts unknown, Cape York Peninsula, Queensland.

Diporiphora pentalineata De Vis, C.W. 1884 . On new species of Australian lizards. Proceedings of the Royal Society of Queensland 1: 97–100 [99]. Type data: holotype – whereabouts unknown, Cape York Peninsula, Queensland.

Diagnosis. Body size moderately large (to 68 mm SVL) with long tail (1.8–2.7 × SVL). Gular and scapular folds absent; post-auricular fold absent or weak. Scales in axilla not granular. Lacks spinose scales on thighs or neck. Pre-cloacal pores 4; femoral pores 0.

Description of syntypes. Juveniles; 30–38 mm SVL; 65–96 mm tail lengths. Small dragons, moderately robust with moderately long limbs and tail. Single canines on each side of upper jaw. Gular, scapular and post-auricular folds absent. Dorsal scales homogenous but raised keels form four prominent longitudinal ridges along dorsum, with a ridge on either side of midline running along the 2nd paravertebral scale row, and a dorsolateral ridge on along each side. These raised vertebral and dorsolateral scale rows extend anteriorly to neck, terminating at head and extending posteriorly onto base of tail. Scales on flanks strongly heterogeneous with scattered scales that are distinctly larger than rest, with keels angling away from dorsum towards ventral surface from midbody. Scales on neck, limbs and tail not spinose. Scales in axilla small but not granular. Ventral scales strongly keeled, keels forming longitudinal ridges running length of body. No pre-cloacal pores visible in these juvenile specimens (usually 4); femoral pores 0.

Dorsum not patterned, which may be due to preservation. Lack vertebral and dorsolateral lines. Dark transverse bands across dorsum absent. Heads plain without patterning, labials same colour to rest of head and lacking pale line between eye and ear. Lacking dark spot on posterior of tympanum. Flanks same colour as dorsum. No lateral stripe between axilla and groin. Faint dark pigmented patch on either side of neck at anterior edge of shoulder. Arms, legs and tail plain. Ventral surface cream with no patterning.

Variation. 54–68 mm SVL; 99–178 mm tail length. Tail long, ranging from 1.8–2.7× SVL. Gular, scapular and post-auricular folds absent in all individuals examined. Dorsal scales homogenous but prominent keels form longitudinal ridges. There are often five longitudinal ridges: one along the vertebral midline, one on either side midline running along the 2nd paravertebral scale row and one on each of the dorsolateral stripes. However, some individuals only have these longitudinal ridges running along the 2nd paravertebral scale row, giving a smoother appearance to the dorsum. Weakly heterogeneous scales in some individuals, with the scale rows second out from the midline being slightly enlarged. Spinose scales absent, but some individuals have 4–6 enlarged (not spinose) scales where a post-auricular fold would occur. Pre-cloacal pores 4; femoral pores 0.

Dorsal patterning variable from plain to strongly patterned. Adult males often have little patterning, but with strongly keeled dorsolateral ridge of scales with a pale cream colour forming prominent dorsolateral stripes. Flanks on these individuals are dark brown with the scattered enlarged pale brown or cream scales giving a speckled or flecked appearance, lacking lateral stripe. Patterned individuals, typically adult females and juveniles, have approximately 4–7 broken dark transverse bands across dorsum on a pale background. Dark bands are of similar width or slightly broader than pale background. These bands are broken by a pale grey or light brown vertebral stripe. The dark transverse bands continue laterally beyond the pale cream dorsolateral stripes, becoming diffuse and terminating at a poorly defined lateral stripe. Wide dark band on sides of neck mostly present, extending from the dorsolateral stripe to the gular ventral surface and anteriorly from where a post-auricular fold would be to the anterior of the shoulder. The dark band is prominent in males and smaller or occasionally absent in females. This dark gular band does not extend onto chest but forms a well-defined posterior edge across the gular region. In adult males, the dark gular band extends anteriorly to the labials, while in individuals with smaller gular bands, the apex of the small central triangle extends anteriorly. Individuals without the dark gular band may have a dark spot on either side of the neck or a narrow grey band across gular. Legs and tail banded in strongly patterned individuals, otherwise little patterning on legs and tail.

Distribution and ecology. Restricted to the eastern edge of the Cape York Peninsula, extending as far south as Mount Misery, southwest of Cairns (fig. 3). Widespread along the eastern extent of Cape York Peninsula, extending inland 150 km from the coast. Little is known about the ecology of this species, but presumed to be similar to that of its sister species D. australis in the NT. If so, it would be a generalist species that occurs in dry open forests, woodlands and shrublands.

Comparison with other species. Overlaps geographically with D. australis , D. nobbi and D. carpentariensis sp. nov. It differs morphologically from both D. australis and D. nobbi in lacking a gular fold. Also differs from D. nobbi in being smaller in body size (65 mm vs. 75 mm SVL), lacking spinose scales on the thighs or neck, having fewer pre-cloacal pores and lacking femoral pores. It differs from D. carpentariensis sp. nov. in that it lacks a scapular fold, scales in axilla are not reduced in size and not granular, scales on flanks strongly heterogeneous with scattered scales that are distinctly larger than surrounding scales, and a black gular band or black spots on sides of neck.

Remarks. Diporiphora jugularis is restricted to the Cape York Peninsula and has been referred to as D. bilineata owing to the lack of a gular fold (e.g. Cogger, 2014; Wilson and Swan, 2017). The distribution maps for D. bilineata usually show a distribution (e.g. Cogger, 2014; Wilson and Swan, 2017), with most of the range in the NT extending across the Gulf of Carpentaria region of Queensland and onto the Cape York Peninsula. However, genetic work has shown that the Cape York Peninsula population is not closely related to D. bilineata and is instead the sister lineage to D. australis ( Edwards and Melville, 2010) , from which it is distinguished by lacking a gular fold (as opposed to a gular fold being present in D. australis ).

There are a number of names available for Diporiphora on the Cape York Peninsula. Examination of specimens held in the type collection at the NHMUK showed that the earliest known treatment of this species was in 1867 by Günther. As detailed above for D. australis , Grammatophora calotella is a replacement name created by Günther in 1867 for a species described earlier in the same year by Steindachner. The Grammatophora calotella treatment was based on BMNH 66.12.28.22–23, but these specimens are the taxon from Cape York Peninsula (i.e. D. jugularis ). However, because Grammatophora calotella Günther, 1867 is a replacement name for Calotella australis Steindachner, 1867 and the account contains no description of that species, these BMNH specimens have no type status. Thus, the first valid description of this species was in 1877: Grammatophora jugularis Macleay.

Figures

Figure 7. Diporiphora jugularis: a, adult male with breeding colouration, Iron Range, Queensland (photo:S. Wilson); b, syntype(s) AMS R40672– 4, juveniles, Cape Grenville, Cape York Peninsula, Queensland.