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| Eutropis alcalai Barley, Sanguila & Brown, 2021 Alcala’s Rough-scaled Sun Skink || facebook.com/PhilippineSystematists |
Abstract
We describe a new species of lizard in the genus Eutropis Fitzinger 1843 from the southwestern tip of the Zamboanga Peninsula on the western part of Mindanao Island, Philippines. The new species is related to Eutropis rugifera, which is a secretive, forest-adapted skink that ranges widely outside the Philippines from the western extent of its distribution on Nicobar Island (the type locality) through southern Peninsular Malaysia, Sumatra and the Mentawai islands, Borneo, Java, and as far east as Bali Island. The discovery of a new, morphologically distinct, and genetically highly divergent Sun Skink lineage in the low elevation forests of Zamboanga Peninsula creates a puzzling disjunct geographic distribution (E. rugifera has not been reported from the Sulu Archipelago). The new species is estimated to have diverged ~10–16 mya from E. rugifera, from which it appears to have an extralimital and isolated distribution. Considering the dynamic geological history and ancient continental origin of the Zamboanga Peninsula, colonization by the new species may have been facilitated by pre-Pleistocene overseas long-distance dispersal, saltatory range expansion and subsequent contraction/extinction in the Sulu Archipelago, and/or possibly paleotransport on the ancient crustal fragment of Zamboanga. The new species is known only from Zamboanga City’s primary surface water supply catchment at the lowest elevations inside the boundaries of Pasonanca Natural Park, despite the fact that there have been historical surveys of herpetological diversity at multiple sites to the northeast (Zamboanga, western Mindanao) and to the southwest (Sulu Archipelago). The new species, thus, may be limited to just the tip of the Zamboanga Peninsula, possibly rendering Pasonanca’s low elevation forests its most critical habitat resource for long term persistence and survival of the species.
Keywords: IUCN Red List, Palawan microcontinent block, Pasonanca Natural Park, Sulu Archipelago, Surface catchment watershed biodiversity
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| Eutropis alcalai sp. nov. (holotype PNM 9878; formerly KU 315013; adult male, SVL 70.1 mm), photographed in life: (a) close-up of anterior body region; (b) full body; collected from Pasonanca Natural Park, Barangay Pasonanca, on the outskirts of Zamboanga City, Zamboanga Peninsula, western Mindanao Island. Photos: Rafe M. Brown. |
Eutropis alcalai sp. nov.
Diagnosis.— Eutropis alcalai sp. nov. can be distinguished from its closest relative, E. rugifera, by its smoother head scales, with light embossing only, and keels limited to posterior margins of parietals, temporals and nuchals (vs. rugose to strongly keeled in E. rugifera), by absence (vs. presence) of contact between the postmental and second infralabial, by the presence of 29–32 (vs. 21–26) subdigital lamellae under the 4th toe, by the presence of seven infralabials (six in E. rugifera), the presence of differentiation in the precloacal scales series (two, medial precloacals enlarged, transversely expanded and bordered on either side by two undifferentiated scales) in E. alcalai sp. nov. (vs. six equal sized scales in E. rugifera), by equivalent length of 3rd and 4th fingers (vs. 4th finger longer than 3rd), and by its white chin and infralabial scales (vs. yellow to orange in E. rugifera).
Distribution.— This species is only known from Pasonanca Natural Park near Zamboanga City at the southwestern tip of the Zamboanga Peninsula. A closely related species (E. rugifera) occurs on Borneo (among other islands of the Sunda Region), and although neither species has been collected from the Sulu Archipelago, one of them may occur on its larger islands.
Etymology.— We take great pleasure in naming this distinctive new species for our colleague Angel C. Alcala, in recognition of his numerous foundational contributions to the natural history, systematics, ecology, and conservation of Philippine lizards of the family Scincidae (Alcala and Brown 1966, 1967; Alcala 1970; Brown and Alcala 1956, 1961, 1963a,b, 1980, 1986). Suggested common name: “Alcala’s Quinque-carinate (Five-keeled) Sun Skink,” or “Alcala’s Rough-scaled Sun Skink.”
Anthony J. Barley, Marites B. Sanguila and Rafe M. Brown. 2021. A New Species of Sun Skink (Reptilia: Scincidae: Eutropis) from the Zamboanga Peninsula, southwestern Mindanao Island, Philippines. Philippine Journal of Systematic Biology. DOI: 10.26757/pjsb2020b14012
