Varanus semotus Weijola, Donnellan & Lindqvist

Weijola, Valter, Donnellan, Stephen C. & Lindqvist, Christer, 2016, A new blue-tailed Monitor lizard (Reptilia, Squamata, Varanus) of the Varanusindicus group from Mussau Island, Papua New Guinea, ZooKeys 568, pp. 129-154 : 132-140

Taxon classification Animalia Squamata Varanidae

Varanus semotus Weijola, Donnellan & Lindqvist sp. n. Figs 1, 2, 3

Holotype.

ZMUT Sa176 (field nr. 60) (Figs 1-2) collected by Valter Weijola just north of the village of Nai , 30 September 2012, 2m elev. Mussau Island, St. Matthias group , Papua New Guinea, latitude -1.525, longitude. 149.749.

Paratypes.

ZMUT Sa177 (field nr 64), ZMUT Sa178 (field nr 66) collected by Weijola near Nai 4 and 7 October 2012. Mussau Island , Papua New Guinea, latitude -1.525, longitude 149.749, ZMUC 4272 (field number E192) and ZMUC 4273 (field number E282) collected by the Noona Dan Expedition (presumably by Søren Andersen) on 19 January and 5 February 1962 at Talumalau, Mussau Island , Papua New Guinea .

Other material.

AMNH 85887 collected by John Gardiner in 1944, St Matthias Islands , Papua New Guinea .

Etymology.

The specific epithet semotus is Latin for distant or remote and refers to the isolated occurrence on Mussau, separated by several hundred kilometers from its closest relatives. The term is employed as a masculine adjective.

Diagnosis.

Varanus semotus sp. n. is distinguished from all other species of Varanus by a combination of the following characters. (1) Tongue white/pinkish to pale yellow (white in preservative) occasionally with small patches of dark pigmentation, the yellow pigment concentrated along the mid-dorsal line and the dorsal surface of the tines (Fig. 2). (2) Gular region marbled in black and cream-white. (3) The tail of adult individuals is indistinctly banded on the distal half, with a varying degree of turquoise to bluish pigmentation on the distal 2/3. (4) Juveniles are black with white spots on the head, yellow and orange spots on the dorsum, and have well defined cream colored to pale greenish tail bands (Fig. 3 C). (5) The number of dorsal scales, XY, ranges from 149 to 153. (6) The number of midbody scale rows, S, ranges from 152 to 161. (7) The dorsum is black with single- and clustered groups of dispersed yellow/orange scales. (8) There are several complete rows of paryphasmata across the asulcal side of the hemipenis below the lobes. (9) Geographical distribution restricted to Mussau Island.

Comparisons.

Varanus semotus sp. n. is a member of the Varanus indicus species group of the subgenus Euprepiosaurus distinguished by the asymmetrical sulcus spermaticus and laterally compressed tail ( Ziegler et al. 2007a). Within the Varanus indicus species group it can be distinguished from all species except for Varanus doreanus , Varanus finschi and Varanus yuwonoi by the presence of yellow pigmentation on the tongue. Varanus semotus is unlikely to be confused with any other species except for Varanus doreanus , from which it can be difficult to distinguish by external morphology. On average, Varanus semotus has lower XY (149-153 vs. 153-215) and S (152-161 vs. 158-180) scale counts than Varanus doreanus . Varanus semotus exhibit several complete rows of paryphasmata crossing the asulcal side of the hemipenis while this is restricted to the medial part of the trunk and lobes on Varanus doreanus (Fig. 4). In contrast to the morphological similarity of these two species, they show a significant genetic separation: 11.5% mean net sequence divergence (dA) (Table 5 B). Varanus semotus is readily distinguished from Varanus finschi and Varanus yuwonoi , both of which have predominately white to cream colored throats and considerably higher scalecounts ( S over 170, XY over 165). Additionally, Varanus finschi lacks blue pigmentation on the tailand exhibits transverse rows of yellow ocelli on the dorsum. Furthermore, Varanus finschi and Varanus semotus have a dA of 6.4% (Table 5 A). Varanus yuwonoi has a unique color pattern being predominantly black on the anterior 1/3 of the body, yellow on the lower back and tailbase, and with a blue tail. Furthermore, Varanus yuwonoi and Varanus semotus have a dA of 11.6% (Table 5 B).

Description of the holotype.

A female of a total length of 1010mm ( SVL: 390mm, F: 620mm). The specimen is well preserved and has an incision running from below the rib-cage to the lower abdomen. There are unhealed lacerations on the ventral part of the tail at around midlength, possibly from a dog bite. The ground color of the dorsal aspect of the body, tail, head and limbs is black. The tail is long and slender, 1.59 times as long as the body, and 38.75 times as long as it is high (16mm) at midlength. It is rounded at the base, becoming increasingly laterally compressed distally starting at 60mm from the base. Two to five middorsal caudal scale rows form a double ridge extending from 1/8 of its length and distally almost to the tip. There are nine discernible blue crossbands each about 6-9 scale rows wide on the distal half of the tail with intermediate blue markings. The ventral scales are white to cream colored with a narrow line of dark brown pigmentation running along the anterior margin. The gular region is dark brown-black and marbled with yellowish and greyish scales. The nostrils are large and round, positioned closer to the snout than the anterior margin of the eye. Nasal capsules expanded forming a groove on the rostrum. The tongue is whitish (in preservative) with small spots of grey-blue pigmentation along the lateral margins. The teeth are long, sharp and only slightly recurved. The limbs are muscular, claws dark-brown and recurved. The head is dark-brown to black and covered with irregular brown-grey markings.

Nuchal scales are slightly domed to flattened, elongate to polygonal immediately behind the head becoming round to oval towards the shoulders and with 1-10 scale pits. Gular scales flattened, round to irregularly polygonal, equipped with 1-5 pits and sometimes bordered by incomplete rows of granules. Mental scales irregular in shape from rectangular to polygonal and elongate. Dorsal scales slightly elongated, rounded or polygonal and with a low central keel. Most are surrounded by an incomplete row of granular scales and with one or two pits located near the posterior end.

Laterodorsal scales are smaller, round, slightly domed, surrounded by granules and with one to three pits. Middorsal caudal scales rectangular, elongate, with a single pit at the posterior end, and lack granules. Mid-ventral caudals twice as long as mid-dorsal caudal scales, elongate and keeled.

Suprafemorals and suprabrachials oval, keeled and surrounded by 1-2 rows of granules. Supratibials irregularly round to oval, polished or keeled and surrounded by 2-3 rows of granules. Infrafemorals round to slightly oval and usually equipped with a row of granules along the distal edge. Infratarsals round to polygonal, highly domed and with a few granules around the corners. Most are light in color and only few have dark pigmented centers. There are rows of 9 enlarged postdigital scales along the outer margin of the fourth hind toe. Infracarpals similar in color to infratarsals, round to slightly polygonal, domed and with granules around the corners.

Dorsal head scales irregularly sized and polygonal, flattened, and equipped with numerous pits. There are seven enlarged supraocular scales on each side, bordered by 1-3 rows of smaller scales. Rostral scale, paired. There are 25+25 enlarged pentagonal supralabial scales equipped with as much as 30 pits. There are 26+26 irregularly shaped infralabials densely covered with pits. Temporal scales square or polygonal, polished and covered with up to ten pits. Two rows of scales separate the supralabials from the nostrils. The occipital scale is enlarged and roundish.The scales on the chest are enlarged, irregularly polygonal, flat and surrounded by only few granules. Ventral scales from the lower chest and down to the abdomen are rectangular, irregularly elongate, bordered by granules along the posterior margin, and with a single pit at the posterior end. The oviducts are translucent white and contains series of ovarian follicles about 10-15mm long.

Scale counts, measurements and proportion indices of the type series.

Are presented in Table 3.

Hemipenal morphology.

The hemipenis of the male paratype ZMUT Sa178 was everted prior to fixation (Fig. 4). The trunks are dark grey pigmented on the asulcal side excluding the lobes. The sulcus spermaticus runs medially on the trunk, turns to the lateral lobe and deflates at the base of the hemibaculum. There are four paryphasmata rows running across the asulcal side of the trunk proximally to the bifurcation of the lobes. About seven additional rows of paryphasmata continues up on the lateral lobe towards the apex. Two rows of paryphasmata runs on the lateral side of the medial lobe as a continuation of the truncal ornamentation. The medial hemibaculum is ossified, quadrangular and slightly decurved. The lateral hemibaculum is smaller, triangular, and with two sharp ends.

Variation and color in life.

The type series is relatively uniform in coloration and pattern. The ground color of the dorsum, tail, legs and head is black. The dorsum and femurs are densely covered by yellow-orange scales, most aggregated in groups of 1-10 (mostly 2-4) scales forming lines, half circles or more rarely complete rings. The markings becomes denser on the neck and changes in color to brown-grey-yellow on the upper neck and head. On the dorsal side of the hands, feet, digits, supratibials and distal 2/3 of the tail most of the light markings are of a blue-green color. On the distal half of the tail these are arrayed in several indistinct transversal bands. The venter is white-pinkish, and with a blue hue on the infratibial surfaces. The upper chest and gular region has an orange-pink hue and is densely marmorated with black on the anterior half. The black markings are paler half adjacent to the gular fold. Photographs from the field allows for a description of coloration of a juvenile (Fig. 3 C). This specimen is black with bright orange and yellow spots on the dorsum, white spots from the shoulder and anteriorly, more or less arrayed in 16 transverse rows between the venter and the head. On the distal 2/3 of the tail these spots turns into 16 complete, well defined whitish crossbands. On the dorsal sides of the legs and around the tailbase the spots are yellow-green. The head is decorated with white patches, and the lips have five white bars on both sides. The iris is dark brown.

Distribution.

Varanus semotus is known so far only from Mussau, an island of 414 km 2 in the northern Bismarck Sea (Fig. 5). According to some of the locals on Mussau, monitors are absent from Emirau, the second largest island of the St. Matthias group, but this needs confirmation from fieldwork. It is also unknown whether this species occurs on the other two nearby islands Emananus and Eloaua.

Natural history.

A total of 16 observations were made during fieldwork on Mussau, all of them along the coast near the village of Nai at the SE corner of the island. Searches in the secondary growth forest of the interior of the island and in the mangrove forests near Palakau did not produce any observations. The relatively dry coastal vegetation near Nai comprises a mixture of coconut palms, pandanus and other trees and shrubs able to persist in the karst, limestone and salt spray affected area (Fig. 6). In this vegetation type monitors appeared to be relatively common. Just south of the village there is a freshwater spring with a small area of Sago palms which was also a popular site for monitors. The lizards were usually spotted either as they were foraging on the ground and quickly fled up in trees, or while they were basking on the trunks of palms or other trees. The specimens collected as vouchers were noosed from trees with a long pole. As is typical of the closely related Varanus doreanus , Varanus finschi and Varanus yuwonoi the specimens were exceedingly aggressive and inclined to bite when captured and handled. Stomach content analysis of the three ZMUT specimens revealed a total of five reptile eggs (3,2,0) and one small skink. All stomachs contained the remains of crabs. Philipp et al. (2007) recorded a bird as the stomach content of ZMUC 4272.

Morphology.

The PCA resolved group structure and only partly overlapping morpho-areas for the four species included (Fig. 7ab). Varanus semotus shows no area overlap on component axes 1-2 and 1-3 while the other three species show full or partial overlap on axes 1-3 (Fig. 7b). Potential sexual dimorphism in scalation characters have not been reported and were not taken into account. PC1 and PC2 accounted for over 80% of the variation with highest loadings on characters S, XY and m (Table 4). Varanus yuwonoi and Varanus finschi associate closely as a result of the mutually high scale counts. The population from Mussau is at the opposite extreme with lower scale counts than the other members. Varanus doreanus , for which the largest sample size was available (all from West Papua), demonstrate a considerable amount of intraspecific variation.

Molecular genetic analysis.

Using PartitionFinder, we selected three data partitions: 16S rRNA + ND4 1st codon positions + tRNAHIS, ND4 2nd codon positions and ND 4 3rd codon positions with the following nucleotide substitution models respectively: TrN+G, HKY+I and TrN. Bootstrap proportions and Bayesian posterior probabilities strongly supported monophyly of conspecific sequences for each taxon where we had more than one sequence available (Fig. 8). Relationships between the taxa were also strongly supported for the most part except for the nodes placing Varanus finschi , Varanus semotus and Varanus yuwonoi , which effectively comprise a polytomy along with a clade comprising the remaining taxa.

A single haplotype was observed for the concatenated 16S rRNA and ND4 sequences among the three Varanus semotus sequenced. Net average uncorrected sequence divergence (dA) between Varanus sister species pairs for ND4 ranged from 1.9% to 14.3% with a mean of 8.7% (Table 5). Net average uncorrected sequence divergence was 6.4% between Varanus finschi and Varanus semotus sp. n. and 2.3% between Varanus cerambonensis and Varanus melinus .