Malayodracon robinsonii ( Boulenger, 1908 )

Denzer, Wolfgang, Manthey, Ulrich, Mahlow, Kristin & Böhme, Wolfgang, 2015, The systematic status of Gonocephalus robinsonii Boulenger, 1908 (Squamata: Agamidae: Draconinae), Zootaxa 4039 (1), pp. 129-144 : 138-140

Taxon— Malayodracon robinsonii ( Boulenger, 1908)

Chresonymy

Gonyocephalus robinsonii — Boulenger 1908: 65; Boulenger 1912: 67

Gonyocephalus robinsoni— Smith 1922: 269

Gonocephalus robinsoni — Smith 1930: 24; Smirnova 2003: 128

Goniocephalus robinsoni — Smith 1935: 133; Sly 1976: 156; Bourret 1947 “2009”: 211

Gonocephalus robinsonii — Smedley 1931: 110; Wermuth 1967: 61; Moody 1980: 299; Denzer & Manthey 1991: 312; Manthey & Denzer 1992a: 16; Manthey & Schuster 1992: 65; Manthey & Grossmann 1997: 189; Chan-ard et al. 1999: 102; Diong et al. 2000: 73; Honda et al. 2002; Denzer & Manthey 2009: 256; Grismer 2011: 258; Pyron et al. 2013

( Gonocephalus inc . sed.) robinsonii — Manthey 2010: 46

Diagnosis. Medium sized lizard; males: SVL 115–158 mm, TL 285–320 mm; females: SVL 115–132 mm, TL 290–300 mm (type specimen, male, SVL 152 mm, TL 320 mm), TL up to 2.6 times SVL; body triangular in crosssection; no patagia; head large, elongated and pointed; bony protuberances on the occipital region; sharp canthus rostralis and rounded superciliary edge; tympanum exposed; antehumeral fold present, transverse gular fold absent; large gular sac; nuchal and dorsal crest continuous; no preanal or femoral pores.

Comparison to other draconine genera. Morphologically Malayodracon robinsonii differs from all other agamid lizards by a combination of the following characters: visible tympanum, bony ridge in the occipital region, large gular sac with a rounded tip extending onto the chest, small weakly keeled, muricate dorsal scales and triangular crest scales.

From its former congeners of the genus of Gonocephalus s. l. it differs additionally by the absence of supporting scales along the nuchal crest (vs. present) and the absence of a distinct transverse gular fold (vs. present). In particular Malayodracon robinsonii differs from the Gonocephalus bellii Group by the possession of triangular nuchal and dorsal crest scales (vs. spines), from the G. megalepis Group by the lack of a large conical scale at the posterior joint of mandibular and maxillar region (vs. present in lacunosus , megalepis and klossi ), from the G. chamaeleontinus Group by the shape of the supraciliary edge (rounded in M. robinsonii vs. angular) and the form of the nuchal crest (single triangular scales in M. robinsonii vs. erected nuchal crest consisting of several scale rows) and G. grandis by the shape of the nuchal crest (crest scales of G. grandis fused similar to a sail).

Malayodracon robinsonii differs from the species that appear in the same node of our phylogenetic analysis as follows: from all Acanthosaura by a lack of a large spine behind the orbit (vs. present in Acanthosaura ) and from all Phoxophrys by an exposed tympanum and the absence of a blue mouth. From Japalura polygonata and J. luei it can be distinguished by the possession of small dorsal scales (vs. large heterogeneous scalation) as well as the possession of a dorsal crest. From all other species of Japalura it can be distinguished by its gular sac pholidosis which is small and smooth in M. robinsonii and enlarged and often keeled in Japalura species. Additionally most Japalura spp. have a concealed tympanum (exceptions are some Indian and Nepalese species formerly referred to as Oriotiaris ( Kästle & Schleich 1998) . From Calotes versicolor and all other species of that genus M. robinsonii differs in pholidotic characters such as small dorsal and gular scales (vs enlarged dorsals in C. versicolor ) and dorsal scales smaller than ventrals (vs. dorsal scales larger than ventral scales in C. versicolor ) as well as the shape of the nuchal and dorsal crest.

Furthermore it differs from the remaining Southeast Asian genera in the subfamily Draconinae as follows:

Aphaniotis Peters, 1864 and Pseudocophotis Manthey in Manthey & Grossmann, 1997 by a visible tympanum; additionally by absence of a blue mouth or a rostral appendage and from Pseudocophotis by the absence of a prehensile tail

Bronchocela Kaup, 1827 by the absence of a lateral skin fold on both sides of the neck

Complicitus Manthey in Manthey & Grossmann, 1997 by the absence of lateral pockets on the gular pouch

Coryphophylax Fitzinger in Steindachner, 1867 by the absence of a nuchal sail and the possession of a dorsal crest

Dendragama Doria, 1888 by cranioskeletal features and gular pouch size

Draco Linnaeus, 1758 by the absence of elongated ribs and patagia

Harpesaurus Boulenger, 1885 and Thaumatorhynchus Parker, 1924 by the absence of a rostral appendage

Hypsicalotes Manthey & Denzer, 2000 by the absence of large plates on either side of the head and the absence of large lanceolate scales along the midline of the gular pouch

Mantheyus Ananjeva & Stuart, 2001 , Ptyctolaemus Peters, 1864 and “ Gonocephalus ” (Genus A) mjobergi Smith, 1925 by the absence of longitudinal skin folds on the gular region

Pseudocalotes Kaup, 1827 by the absence of rhombic dorsal scales

General description. The holotype (see Figure 1 ) has been described in Boulenger (1908) and several aspects including variation were added by Smedley (1931) after additional material became available. A very detailed description of Malayodracon robinsonii (as Gonocephalus robinsonii ) is given in Grismer (2011).

Head scales small; scales on the supraciliary edge longer than wide; nasal in contact with first supralabial, sometimes also with second; typically 8 supra- and 8 infralabial scales (maximum 10 each). Slightly enlarged scales on the prominent v-shaped protrusion in the occipital region; large conical scale on either side of occiput. Gular pouch large, reaching the chest, tip rounded; gular scales small, homogeneous, smooth or slightly keeled.

Body elongated, laterally slightly compressed; dorsal scales nearly homogeneous, small, keeled, directed backwards and upwards intermixed with several—usually five or six—parallel oblique rows of enlarged scales. Scale numbers around midbody sometimes exceeding 100. Nuchal and dorsal crests continuous consisting of a single row of flat triangular—in some specimens lanceolate—scales touching at the base and decreasing in size caudad. Ventrals significantly larger than dorsals, keeled. Subdigital lamellae keeled, 31–36 on fourth toe. Tail long, roundish in cross-section. Enlarged scales along the mid ridge of the tail, continuous with dorsal crest. Underside of tail with strongly keeled scales.

Adults in life typically dark green dorsally and dorsolaterally, dirty white ventrally; sometimes ground colour yellowish green (see Figure 5 ). Gular sac typically reddish brown, greyish or black, continuously darkening towards the tip. A dark shoulder patch and dark oblique cross bands often visible. Enlarged dorsal scales (if present) often coloured much lighter than surrounding body colouration, forming bands. Labials and area below tympanum (plus tympanum) conspicuously white. Colour dependent upon age. Juveniles typically yellowish brown ground colour with brown cross bands. Labials in juveniles rather dirty white to pale brown, shoulder patch brown. In alcohol the colour fades and grey tones are prevalent (s. photograph of the type specimen in Figure 1 ). However, the black shoulder patch and dark dorsal cross bands remain discernible.

Variation. Hitherto known specimens from the type locality (Gunung Tahan) do not show enlarged dorsal scales arranged in oblique rows ( Boulenger 1908, Sly 1976) as it can be seen in specimens from the Cameron Highland region. It is conceivable that these two populations have been separated for a long time and constitute subspecies. However, in order to establish consistency of this character more material from the remote mountain ranges of central Malaysia is needed. Additionally there exists a photographic record of a specimen from the Cameron Highlands without apparent enlarged scales across the dorsum rendering the above observation doubtful.

Distribution. Malayodracon robinsonii is restricted in its distribution from mid to high altitude areas of the peninsular Malaysian highlands (approx. 600–1500 m asl) inhabiting submontane and montane forests. M. robinsonii shares this isolated distribution with several other reptile species that are restricted to the Cameron Highlands or the central mountain ranges of Malaysia (Fraser and Larut Hills; Genting Highlands) such as Trimeresurus nebularis Vogel, David & Pauwels, 2004 , Hebius sanguineus ( Smedley, 1931) , Macrocalamus tweediei Lim, 1963 and Collorhabdium williamsoni Smedley, 1931 . Endemism on genus and species level is comparatively high in this geographical area.

Malayodracon robinsonii has been reported from Genting Highlands (Ulu Kali), Cameron Highlands (Tanah Rata, Gunung Brinchang, Gunung Beremban, Gunung Jesar) and further north from its type locality Gunung Tahan.

Etymology. The name Malayodracon was chosen to express that the type and currently only known species of the genus is restricted to Malaysia (latinized malaya, male form malayo owing to the gender of the ending -dracon) and constitutes a genus belonging to the subfamily Draconinae (gr. drakon / δράκων; a serpent in Greek mythology; latinized dracon = engl. dragon).

Figures

FIGURE 1. Ventrolateral view of the head, gular and pectoral regions (“ Gonocephalus ” robinsonii holotype BMNH 1946.8.14.81)

FIGURE 5. Malayodracon robinsonii from Tanah Rata, Cameron Highlands, West Malaysia. Photo: U. Manthey.