Latest Addition to Local Herpetofauna
By Risidra Mendis
A new species of the genus Ceratophora Gray, 1835 (Reptilia: Agamidae) was discovered from a lowland rainforest in Sri Lanka, by a group of researchers on a mission to save what is left of our rich biodiversity.
The new species Ceratophora ukuwelai sp. nov. was discovered by Nature Explorations and Education Team consisting scientists; Suranjan Karunarathna, Nikolay A. Poyarkov, Chamara Amarasinghe, Thilina Surasinghe, Andrey V. Bushuev, Majintha Madawala, Vladislav A. Gorin, and Anslem De Silva.
“The genus Ceratophora (horn-lizards) comprises six species, all of which are endemic to Sri Lanka. The new species of Ceratophora is described based on morphological and molecular evidence. The new species is restricted to the Salgala Forest in the Kegalle District, and most closely resembles Ceratophora aspera Günther, 1864,” Karunarathna explained.
He said Sri Lanka and the Western Ghats of India are collectively recognised as a biodiversity hotspot, rich in both diversity and endemism among the herpetofaunal assemblages. “However, this area supports the highest human population density among the world’s biodiversity hotspots. The evolutionary and phylogenetic uniqueness of Sri Lanka’s herpetofauna has been well-established. According to the International Union for Conservation of Nature (IUCN) Red List criteria, the new species is categorised as ‘Critically Endangered’ (CR) due to its range-restricted habitat,” Karunarathna said.
The researchers stress that among Sri Lanka’s herpetofaunal assemblages, the agamid lizards warrant scientific attention. “The 21 species of agamid lizards in Sri Lanka belong to six genera, and include 19 (90.5 per cent) species endemic to the island. The newly discovered species, Ceratophora ukuwelai sp. nov. from the Salgala Forest was highly divergent from other congeners and differed from its sister species Ceratophora aspera by the presence of fewer paravertebral scales, greater mid body scales, fewer ventral scales, trunk being relatively long, and fore body being relatively short,” the researchers said.
The Salgala Forest is in the Kegalle District, Sabaragamuwa Province. The area falls within the northern border of the wet bioclimatic zone, where tropical evergreen rainforests comprise the dominant vegetation type. The forest acreage is approximately 150 hectares and Salgala forest is isolated from other forest massifs by the Kelani River and Maha River valleys, numerous perennial middle-order streams, and human modified cultural landscapes such as tea plantations. The mean annual rainfall in the area varies between 2,500 and 3,500 mm, most of which is received during the southwest monsoon from May to September.
Five individuals recorded
“Salgala is rich in tall rainforest trees and the forest floor contains thick leaf litter. Numerous smaller streams are present within the type locality. Ceratophora ukuwelai sp. nov. appears to be an elusive and rare species in Salgala as only five individuals were recorded during 10 field excursions (nearly 500 person-hours). Specimens of the new species were recorded on the forest floor in dense forest patches with thick and wet leaf litter under dense canopy cover. The microhabitat of Ceratophora ukuwelai sp. nov. was a poorly illuminated, relatively moist, canopy-shaded, and relatively warm environment at the time of our survey. The new species was recorded with several other agamid lizard species,” Karunarathna explained.
The researchers said this study demonstrates that the northernmost portion of its range actually harbours a new species, Ceratophora ukuwelai sp. nov. and in the present paper they recommend that Ceratophora ukuwelai sp. nov. be listed as a CR species. “The infrequent encounter rates of this species in its habitat and continuing habitat loss are the primary reasons for our conservation status assessment. In addition, Sri Lanka’s southwestern lowland rainforests are severely fragmented; as such, edge effects and concomitant micro-environmental changes and subsidised predation risk could further endanger this species. The threats to agamid lizards would appear to stem largely from habitat loss and fragmentation,” the researchers said.
They added that the impacts of fragmentations could also be exacerbated by the fact that many important montane forest fragments are surrounded by vegetable and tea plantations and worse yet vegetable cultivation in Sri Lanka involves the intensive and indiscriminate application of pesticides.
“The major threats for this species are habitat loss due to expansion of commercial-scale agriculture and monoculture plantations, as well as illicit forest encroachments. Highways also pose a threat to animals, not only by means of habitat fragmentation, but also by resulting in direct mortality in terms of incidental road kills. The asphalt surfaces of these highways reach thermally intolerable levels, which could induce physiological stress. The exotic pet trade and alien invasive species are growing threats for Sri Lankan lizards. In addition, predation by feral or domestic cats can also result in considerable mortality among agamids,” Karunarathna said.
They added that further studies on the natural history and behaviour of endemic lizards of Sri Lanka are essential for better planning and implementation of scientific conservation and management programmes. “The promotion of ecological and behavioural studies in schools and universities is required for assessing habitat fragmentation and human impacts on Sri Lankan endemic agamid lizards. Further development of public awareness workshops and conservation action plans are necessary for the conservation of agamid species. Reducing road kills at road crossings and migration routes and further development of public awareness through the organisation of workshops are important steps for the implementation of a conservation action plan for Sri Lankan agamid conservation. We are also unaware of any substantial ex-situ efforts in the captive breeding of agamids. Sri Lanka’s zoological and botanical gardens should explore the feasibility of such efforts,” the researchers said.
(Pix courtesy Suranjan Karunarathna and Sanjaya Kanishka)