Varanus tanimbar Weijola & Kraus 2023, sp. nov.
Creators: name: Weijola, Valter
name: Kraus, Fred
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Squamata
Varanidae
Varanus
Varanus tanimbar

description: Varanus tanimbar sp. nov.
(Figures 8–12)
Holotype
WAM112255 (Figure 8) collected by Richard How (RH), Ronald Johnstone (RJ) and Darrell Kitchener (DK), 24 April 1993, at Latdalam, Yamdena Island, Tanimbar Islands, Indonesia.
Paratypes
WAM109940 (Figure 9) collected by RH, RJ and DK, 20 April 1993, at Latdalam, Yamdena Island, WAM109896 collected by RH, RJ and DK, 18 April 1993, at Lorulun, Yamdena Island, and WAM112323 collected by RJ and I. Maryanto, 27 April, at Adaut, Selaru Island, Tanimbar Islands, Indonesia.
Etymology
The specific epithet tanimbar is a noun in apposition and refers to the Tanimbar Archipelago of Maluku, Indonesia, to which this species is endemic.
Diagnosis
Varanus tanimbar sp. nov. is a member of the subgenus Euprepiosaurus, which is defined by having the unique combination of an asymmetric sperm groove and laterally compressed tail (Ziegler et al. 2007). Molecular phylogenetic analyses place it within the V. indicus species group defined by the unilateral paryphasmata ornamentation of the hemipenis and lack of blue pigmentation on the tail (Ziegler et al. 2007; Weijola et al. 2019). It can be distinguished from all other species of Euprepiosaurus by its unique combination of: (1) dorsum black with more or less well-defined crossbands composed of lemon-yellow ocelli and/or dots; (2) tail black with distinct yellow bands; (3) dorsal aspect of tongue blue-grey; (4) temporal region typically ornamented with a dark temporal band and a lemon-yellow postocular stripe; (5) venter pale yellow; (6) mid-body scale rows (S) 145–161; (7) mid-dorsal scale rows (XY) 159–170; (8) ventral scale rows (T) 107–109; (9) scales around neck (m) 109–119.
Comparisons. Varanus tanimbar sp. nov. is the only species of Varanus known to occur in the Tanimbar Islands. It can be distinguished from other allopatric species of Euprepiosaurus present in the Moluccas by differences in scalation and colour pattern: from V. caerulivirens and V. yuwonoi by the lack of blue pigmentation on the tail (vs present in V. caerulivirens and V. yuwonoi), from V. obor and V. zugorum by its black dorsum with rows of yellow ocelli (vs solid black in V. obor and solid brown in V. zugorum), from V. melinus by its black (vs yellow in V. melinus) head and dark grey/ blue tongue (vs pink in V. melinus), and from V. rainerguentheri by having the dorsal pattern of yellow ocelli arrayed more or less into crossbands (vs more irregularly scattered yellow spots in V. rainerguentheri) and the higher mid-body (S) scale counts (145–161 in V. tanimbar vs 120–139 in V. rainerguentheri).
Within the V. indicus group, Varanus tanimbar sp. nov. is only likely to be confused with the allopatric V. colei, V. douarrha, V. finschi, V. indicus, V. lirungensis or V. louisiadensis sp. nov., with which it shares a similar dorsal pattern composed of transverse bands of yellow ocelli. It can be distinguished from V. colei, V. douarrha, V. finschi, V. lirungensis, and V. louisiadensis sp. nov. by the typical presence of a distinct yellow postocular stripe (vs absent in the other species). It can be distinguished from V. indicus by its completely blue-grey tongue (vs bicoloured pink and grey in V. indicus) and higher average scale counts in characters S (154 vs 141.4), T (107.5 vs 96.3) and m (112.5 vs 103.3).
Description of the holotype. Juvenile, abdomen opened with both single vertical and longitudinal slits; basal 1/3 of tail with longitudinal cut along ventral side. Habitus slender, total length 500 mm, SVL 200 mm, tail length 300 mm; head elongate. Ground colouration of dorsum, neck and head dark brown to black; densely scattered with pale grey/blue (yellow in life) scales; small blotches and rings/rosettes indistinctly arranged as crossbands over dorsum. These rings and spots are composed of grey/blue (yellow in life) scales; the skin surrounding the scales is grey/black. Tail black, banded on distal 2/3 of length by 17 indistinct bands, each 5–7 scale rows wide. Tail 1.5 times as long as body, relatively elongate (36.14 times as long as high at midlength). Dorsal keel formed by 1–4 enlarged mid-dorsal caudal scales starting at ~ 35 mm posterior to tail base. Tail round at base, becoming triangular where keel is formed and increasingly laterally compressed to around midlength. Ventral ground colour pale cream, intersected by numerous (23) grey crossbands between cloaca and gular fold.
Ventral sides of limbs cream coloured and intersected by mosaic of narrow grey bands. Pale cream stripe 10–12 mm (~18 scale rows) wide between snout and gular fold; throat rapidly turning marmorated lateral to this. Tail cream ventrally, densely covered by indistinct grey crossbands most clearly visible on basal and distal 1/3 of tail. Limbs black dorsally with white/grey (yellow in life) spots composed of about 1–7 scales.
Head 1.96 times as long as wide, dorsal aspect black with small amount of white on most scales, yellow parietal scale, dark temporal band ~5 scales wide, and white postocular stripe ~2 scales wide. Supralabials and infralabials paler than rostrum and dorsal aspect of head. Nostrils slightly elongate, pointed at anterior corner, closer to snout than to eye. Nasal capsules slightly expanded, with shallow sagittal groove on rostrum.
Nuchal scales of irregular shape on upper neck, round at mid-neck, and increasingly elongate towards shoulders; nuchals domed, with one to several scale pits, surrounded by one or two rows of granules. Dorsal scales oval, slightly irregular in size, domed or keeled (towards abdominal region), most with single pit posteriorly and surrounded by single row of granules. Lateral caudal scales rectangular, elongate, with a single pit centrally or posteriorly. Ventral caudal scales rectangular, elongate, strongly keeled, twice length of mid-dorsal caudals, occurring in row of 10 at midlength of tail. Ventral scales of pubic region polygonal to round, bordered posteriorly by row of granules. Abdominal scales rectangular with rounded corners, bordered posteriorly by row of granules. Ventral scales become increasingly less elongate and round towards chest and finally quadrate or polygonal and irregular in shape near gular fold; ventrals polished, often equipped with single pit and with few granules posteriorly. Gular scales rounded with few granules along posterior edge but become oval to rectangular and elongate towards mental region; mental scales larger laterally, rectangular or polygonal and densely covered in pits.
Infrafemorals and infratibials round or polygonal, often with a few granules along posterior margin. Infracarpals and infratarsals round, of irregular size, highly domed. Subdigital scales irregular in size and shape, highly domed to almost flat. Twelve rows of enlarged scales along outer margin of fourth toe; four slightly enlarged scales along outer margin of third toe. Claws brown/translucent, sharp, recurved.
Occipital scales relatively small, irregular, polygonal. Five enlarged, irregularly shaped supraocular scales, elongate rectangular to pentagonal, densely covered with pits. Scales on forehead and rostrum larger than occipital scales, polygonal, flattened. Supralabials rectangular or pentagonal, covered with pits. Infralabials of irregular size, triangular or polygonal. Tines and dorsal aspect of distal half of tongue grey. Lateral sides of tongue white with only a small amount of grey pigment; distal half of ventral aspect pale blue with a grey central groove.
Scale counts. S: 158, XY: 159, DOR: 170, T: 107, VEN: 128, X: 44, m: 109, P: 43, Q: 91.
Measurements. SVL: 200 mm, F: 300 mm, TL: 500 mm, E: 125 mm, D: 75 mm, A: 35.3 mm, B: 18 mm, C: 12.5 mm, G: 10.8 mm, H: 7.0 mm, I: 18.0 mm.
Scale counts, measurements and proportion indices of the type series. See Table 3.
Variation and colouration in life. The paratypes are similar to the holotype although there is some variation in the amount of dark pigmentation on the gular region, venter and ventral surfaces of limbs (Figures 8, 9). While most individuals have a well-defined yellow temporal band, this was absent in one of seven individuals seen by us (Figure 12). In life, dorsal ground colour black; throat, dorsal spots, and ocelli greenish lemon-yellow (Figures 8–12). Tongue pink basally with grey blue on tines and dorsodistal half.
Range. Varanus tanimbar sp. nov. is known from Yamdena and Selaru – the two largest islands in the Tanimbar Archipelago. The species is also likely to occur on surrounding islands such as Larat, Fordate, Wotap, Wuliaru, Selu and Sera, but its presence on those islands needs confirmation.
Natural history. There are no specific details about the biology of this species, but it is likely similar in diet and habitat preferences to other closely related species of the V. indicus group, which are habitat generalists of mangroves, coastal, and lowland forests (Weijola and Sweet 2015). During a brief visit to Yamdena in 2009, VW found the species being hunted for food by local residents, and this might well suppress populations in the vicinity of human settlements.
Remarks
Varanus tanimbar sp. nov. formed a well-supported clade together with the Moluccan species V. indicus and V. melinus in the BEAST analysis based on the 16S and ND4 markers used by Weijola et al. (2019). Within this Moluccan clade, V. tanimbar sp. nov. formed a basal sister lineage to the closely related V. indicus and V. melinus. ND4 pairwise distances between V. tanimbar sp. nov. and these two species are 3.4% and 3.9%, respectively, and 2.3% between V. indicus and V. melinus (Weijola et al. 2019).
description: Published as part of Weijola, Valter & Kraus, Fred, 2023, Two new species of monitor lizards (Squamata: Varanus) endemic to the Louisiade and Tanimbar Archipelagos with a key to the subgenus Euprepiosaurus, pp. 947-975 in Journal of Natural History 57 (13 - 16) on pages 959-964, DOI: 10.1080/00222933.2023.2218574, http://zenodo.org/record/8221626