Varanus palawanensis KOCH, GAULKE & BÖHME, 2010
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Varanus palawanensis
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| Higher Taxa | Varanidae, Platynota, Varanoidea, Anguimorpha, Sauria, Squamata (lizards) |
| Subspecies | |
| Common Names | |
| Synonym | Varanus palawanensis KOCH, GAULKE & BÖHME 2010 Varanus (Soterosaurus) palawanensis — KOCH et al. 2010 Varanus (Soterosaurus) palawanensis — BUCKLITSCH et al. 2016: 50 |
| Distribution | Philippines (Palawan; Balabac and the Calamian Island group including Calauit and Busuanga; Sibutu Island within the Sulu Archipelago) Type locality: Tabon, Palawan Island, Philippines |
| Reproduction | oviparous (not imputed, fide Zimin et al. 2022) |
| Types | Holotype: SMF 73912 (Figs. 25–27), adult male, collected by M. Gaulke 19.I.1989, donated 6.IV.1989. Paratypes. SMF 73914–15, 2 adults males, Tabon, Palawan Island, collected by M. Gaulke, I.1989, donated 6.IV.1989; BMNH 94.6.30.19, subadult, Palawan Island, collected by A. H. Everett, 1894; BMNH 94.6.30.20, adult (Fig. 28), Palawan Island, collected by A. H. Everett, 1894; MNHN 1884-187, adult (mounted), “Ile Paragua” (= Palawan), collected by A. Marché, ca. 1883; ZMUC E78, subadult, Dalawan Bay, Balabac Island, collected by the Noona Dan Expedition, 8.X.1961; ZFMK 89691 (formerly SMF 73913), adult male, Tabon, Palawan Island, collected by M. Gaulke, I.1989, donated 6.IV.1989. |
| Diagnosis | Diagnosis: This new water monitor species is characterised by the following combination of characters that distinguishes V. palawanensis sp. nov. from all congeners: (1) relatively high scale counts around the head from rictus to rictus (character P = 53–65, mean = 56.64), (2) but low scale counts around the body (character S = 129–148, mean = 139.00), (3) and mean scale counts along the dorsal side (character XY = 116–145, mean = 128.27). For the remaining scalation features we refer to Table 3. Moreover, (4) the salvator-typical colour pattern of dorsal transverse rows of big bright spots and a bright and dark banded tail is indistinct in V. palawanensis sp. nov., and replaced by a vague pattern of bright mottling consisting of many single or bright bordered scales. Instead, (5) specimens often exhibit white markings on the head, (6) but a bright lateral temporal streak extending between eye and ear opening is poorly defined. (7) The dark bluegreyish tongue is flesh-coloured only at its base. (8) Ventrally, the throat shows no dark lateral bars but is mottled with dark brown scales. For details about scalation features and colour pattern of the remaining Philippine members of the V. salvator complex we refer to Tables 3 and 5 in KOCH et al. 2010. Comparisons with other Philippine Varanus taxa. V. palawanensis sp. nov. is distinguished from the remaining Philippine members of the V. salvator complex by its reduced dorsal colour pattern. Only V. rasmusseni sp. nov. and V. marmoratus show the same tendency in adult specimens. However, latter species are either characterized by an increase (V. rasmusseni sp. nov.) or a reduction (V. marmoratus) of dorsal transverse rows of bright spots in juveniles. In addition, whitish markings of varying extent on the head are only known from V. nuchalis, which, however, is clearly differentiated by enlarged nuchal scales (character XY = 94–138, mean = 109.45 vs. 116–145, mean 12.14 in V. palawanensis sp. nov.). Note that at present due to the small sample size it cannot be excluded that V. rasmusseni sp. nov. also may show white blotches on the head. In tongue colouration, V. palawanensis sp. nov. resembles V. s. macromaculatus from Borneo which also exhibits dark blue-greyish pigmentation on the dorsal side and below, while the remaining Philippine water monitor populations have a flesh-coloured ventral side of the tongue. Compared to V. marmoratus, V. palawanensis sp. nov. exhibits significantly more scales around the base of the tail (character Q = 98–119, mean = 105, vs. 85–107, mean = 94.73), and along the dorsal side (character XY = 116–145, mean = 127.14, vs. 101–123, mean = 110.80). Compared to V. s. macromaculatus from Borneo, V. palawanensis sp. nov. has the nostrils on average further apart from the tip of the snout (index 2 = 1.69–2.20, mean = 1.90, vs. 2.00–2.80, mean 2.16; P = 0.018). It has fewer scales around the tail after one third of its length (character R = 48–70, mean = 56, vs. 53– 70, mean = 61.15; P = 0.014), around midbody (character S = 129–178, mean = 141.93, vs. 142–170, mean = 152.05; P = 0.029), on the dorsal side (character XY = 116–145, mean = 127.14, vs. 125–172, mean = 151.20; P < 0.0001), fewer supraoculars (character U = 10–14, mean 12, n = 14, vs. 12–19, mean = 14.33, n = 9; P = 0.006), and fewer supralabials (character c = 59–63, mean = 60.64, n = 14, vs. 58–70, mean = 65.25, n = 20; P < 0.0001). In addition, the salvator-typical colour pattern is only rarely expressed in V. palawanensis sp. nov. Despite a similarity in colour pattern of adult specimens between V. rasmusseni sp. nov. and V. palawanensis sp. nov., the latter species has larger and, therefore, fewer scales on the dorsal side (character TN = 155–176, mean = 169.50, vs. 183–187, mean = 185), and around the neck (character m = 93–116, mean = 101.15, vs. 120–129, mean = 124.50). |
| Comment | This species may have been previously identified as V. salvator marmoratus. According to the timetree in Fig. S3 of Brennan et al. (2020), several taxa within the V. salvator group are distinctly younger than 1 million years, such as cumingi, marmoratus, palawanensis, and samarensis, hence they may be better considered as subspecies of V. salvator (Ziegler & Vences 2020). |
| Etymology | The specific epithet palawanensis refers to the type locality Palawan Island, Philippines. |
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