Sytematics, Ecology and Biogeography of the Gekkonid Genus Cnemaspis in Sarawak, Borneo (Sauria: Gekkonidae)

Izneil Nashriq, Mohamad Nasir (2020) Sytematics, Ecology and Biogeography of the Gekkonid Genus Cnemaspis in Sarawak, Borneo (Sauria: Gekkonidae). Masters thesis, Universiti Malaysia Sarawak (UNIMAS).

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Abstract

A remnant of what was once a gigantic landmass, Sundaland, is today recognised in the form of the Sunda Shelf, on which the island of Borneo sits, and is a known biodiversity hotspot for a large number of species from many lineages, many of them endemic. One of these, which has attracted the attention of taxonomists in the recent past is the Old World gekkonid genus Cnemaspis. Only five species were described from the Island of Borneo till 2017, which is in contrast to the large number recently recorded from the Asian mainland. This raises a question whether there are more species that remain undescribed. The described species are listed here: Cnemaspis kendallii, a forest-adapted species resides in primary as well as secondary forest within formation of sandstones and limestones. Cnemaspis nigridia is restricted to the granite formation of western Sarawak in the Lundu Division. Cnemaspis dringi is only known from Labang Camp, Bintulu, and from Sungai Segaham, Belaga, taken from under a log. Cnemaspis paripari is rupicolous, residing in karst formation of the Bau limestone. Cnemaspis leucura is restricted to the Kayan Sandstone formation of Gunung Penrissen. Using a taxonomic and phylogenetic approach, this study describes additional members of Bornean Cnemaspis and documents novel ecological information, in addition to making biogeographical remarks. Two new species are identified: Cnemaspis matahari sp. nov. from Serian Division of western Sarawak and Cnemaspis lagang sp. nov. from the Miri Division of northern Sarawak. Cnemaspis matahari sp. nov. is identifiable by having an SVL up to 56 mm; 10 to 14 supralabials; nine to 13 infralabials; two to three internasals; five to nine postmentals; keeled ventral, forearm, and subtibial scales; six to 12 discontinuous precloacal pores; ventrolateral caudal tubercles absent; lateral row of caudal tubercles present; caudal tubercles not encircling tail; subcaudals keeled, bearing an enlarged median row of smooth scales; four to six postcloacal tubercles on each side of tail base; no enlarged femoral or subtibial scales; submetatarsal scales of first toe enlarged; 24 to 31 subdigital fourth finger lamellae; head, limbs, and regenerated tail yellow in males; posterior one-half of original tail white in males. Cnemaspis lagang sp. nov. is identified by having an SVL up to 46 mm; 13 to 14 supralabials; 10 to 11 infralabials; three internasals; eight to 10 postmentals; keeled ventral, forearm, and subtibial scales; eight precloacal pores; two postcloacal tubercles; subcaudals keeled; no enlarged femoral or subtibial scales; submetatarsal scales of first toe enlarged; and 20 to 22 subdigital fourth finger lamellae. Both species inhabit lowland karst landscapes. Cnemaspis matahari sp. nov. is restricted to the Kedadom and Padawan limestone formation of the western Sarawak while C. lagang sp. nov. is known only from the Mulu limestone formation of northern Sarawak. The distribution of the geckos are mostly fragmented and concentrated on the western Sarawak. With Lupar Line as an indication of Quaternary vicariance dividing between biota of west and north Sarawak, the current distribution of Cnemaspis is further fragmented with human activities such as limestone mining and conversion of land for plantation and development. These studies suggest the existence of additional undescribed species from karst landscapes within the tropical forests of Borneo.

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