Varanus bitatawa sp. nov.
The specific epithet is derived from bitatawa, the Agta tribespeoples' common name for the new species.
(b) Holotype and paratypes
Holotype: PNM 9719 (formerly KU 320000; LJW field number 071), adult male, salvaged from hunter at the base of the San Ildefonso Peninsula, Sitio Casapsipan, Barangay Casiguran, Municipality of Casiguran, Aurora Province, Luzon Island, Philippines (16.286667° N, 122.185833° E, WGS-84; 1 m above sea level), 29 June 2009. Paratypes: KU 322188 (ACD 2796), juvenile male, from Sitio Dunoy, Barangay Dibuluan, Municipality of San Mariano, Isabela Province, Luzon Island, Philippines (200 m above sea level), April 2006; collected by A. C. Diesmos; PNM 9008, female, collected from the same locality on 16 July 2005 by R. Dugay.
Varanus bitatawa differs from congeners by the combination of (i) large, robust body (and related scalation differences: ), (ii) contrasting black and golden yellow dorsal coloration, (iii) dark gular coloration in juveniles, (iv) anteriorly directed, slit-like external nares, and (v) multiple characters of hemipeneal morphology (; electronic supplementary material). Additionally, the new species is distinguished from congeners by marked divergence in mitochondrial and nuclear gene sequences and differs from its closest relative, V. olivaceus, by genetic divergence in excess of the divergence between other Asian species ( and ; electronic supplementary material, figure S2 and table S3). Detailed comparisons are provided in the electronic supplementary material.
Table 1. Characters distinguishing V. bitatawa from close relatives. Ranges for snout–vent and tail length of V. olivaceus represent our data combined with Auffenberg (1988; 90 specimens) and D. Bennett (2009, unpublished; 28 specimens); dashes, missing (more ...)
Figure 2. Dorsal views of bodies, lateral views of heads and close-ups of hemipenes of (a) V. bitatawa (PNM 9719) and (b) V. olivaceus (KU 322187). Letters indicate: A, primary apical hemibaculum horn; B, secondary apical hemibaculum horn; and C, presence or absence (more ...)
Table 2. Uncorrected mitochondrial DNA sequence divergence (%) in V. bitatawa, V. olivaceus and three clades of Varanus (). Percentages on the diagonal represent intraspecific (or within clade) genetic diversity. See electronic supplementary material (more ...)
(d) Brief description of holotype
A large-bodied species of Varanus, holotype snout–vent length (SVL) 766 mm, tail 1036; head robust, length 124.9, width 73, maximum depth 66.8, depth at eye 45.4; snout length 65.7; snout rounded anteriorly; narial openings slit-like, surrounded by an elevated protuberance; cranial table squarish, wider than long, with hypertrophied adductor musculature; head scales heterogeneous; supralabials 58; infralabials 66, decreasing in size to rictus; nuchals large, polygonal, decreasing in size laterally; scales arranged in 56 semi-regular rows from the posterior margin of the cranial table to forelimb insertion; scales of the dorsal trunk smaller than those on the head, polygonal; scales in 94 rows in the axilla–groin region; paravertebrals from the gular fold to the anterior edge of hindlimb insertion 127; axilla–groin distance 272 mm; limb scales large, polygonal, slightly convex, decreasing in size distally; forelimb and hindlimb 164 and 198 mm respectively; digits terminating in robust, recurved claws; scales of manus and pes squarish, smaller than those of trunk; supradigitals ovular; caudals rectangular, in semi-regular rows; scales around the base of the tail 101, around the tail one-third from the base, 59; double keel of paired, raised rectangular scales originating 110 mm from the base and extending posteriorly to tail terminus; ventrals less variable than dorsals; ventral nuchals small, increasing in size and becoming squarish through the mid-nuchal region, then decreasing in size anterior to the gular fold; scales around the neck anterior to the gular fold 145; gulars in 68 rows between the gular fold and the margin of the tympanum; ventrals posterior to the gular fold heterogeneous, larger than nuchals; scales in the scapular region polygonal, increasing in size posteriorly; midbody scales 193; ventrals from the gular fold to the anterior margin of hindlimb insertion 107; total ventrals 227; precloacals irregular, round to polygonal, decreasing in size distally through limbs; subcaudals small, heterogeneous, increasing in size posterior to the hemipenal bulge. Dorsal ground coloration black, accentuated with bright golden yellow in life; dorsum covered with golden yellow spots and flecks; head speckled yellow on black; forelimbs more yellow than black; trunk traversed by four distinct rows of yellow oscelli; hindlimbs black with large, distinct, yellow spots; tail barred, contrasting black and yellow. Detailed description of the type series is provided in the electronic supplementary material.