103 Amphib. Reptile Conserv. October 2020 | Volume 14 | Number 3 | e259 Amphibian & Reptile Conservation 14(3) [Taxonomy Section]: 103–126 (e259). A new species of the genus Ceratophora Gray, 1835 (Reptilia: Agamidae) from a lowland rainforest in Sri Lanka, with insights on rostral appendage evolution in Sri Lankan agamid lizards 1, *Suranjan Karunarathna, 2,3, *Nikolay A. Poyarkov, 1 Chamara Amarasinghe, 4 Thilina Surasinghe, 2,3 Andrey V. Bushuev, 5 Majintha Madawala, 2 Vladislav A. Gorin, and 6 Anslem De Silva 1 Nature Explorations and Education Team, No. B-1 / G-6, De Soysapura Flats, Moratuwa 10400, SRI LANKA 2 Department of Vertebrate Zoology, Lomonosov Moscow State University, Leninskiye Gory, GSP–1, Moscow 119991, RUSSIA 3 Joint Russian-Vietnamese Tropical Research and Technological Center, 63 Nguyen Van Huyen Road, Nghia Do, Cau Giay, Hanoi, VIETNAM 4 Department of Biological Sciences, Bridgewater State University, Bridgewater, Massachusetts, USA 5 Victorian Herpetological Society, PO Box 4208, Ringwood, Victoria 3134, AUSTRALIA 6 Amphibia and Reptile Research Organization of Sri Lanka, 15/1, Dolosbage Road, Gampola, SRI LANKA Abstract.—The genus Ceratophora (horn-lizards) comprises six species, all of which are endemic to Sri Lanka. Herein, a new species of Ceratophora is described based on morphological and molecular evidence. The new species is restricted to the Salgala Forest (~300 m asl elevation) in the Kegalle District of Sri Lanka, which is in the northern part of the wet bioclimatic zone. The new species most closely resembles Ceratophora aspera Günther, 1864, but can be distinguished from it by body proportions, number of paravertebral and ventral scales, and ND2 mtDNA data. Complete morphological description of two syntypes of C. aspera are also provided, in addition to a key to the species of genus Ceratophora. The phylogenetic relationships and evolution of rostral appendages in Sri Lankan agamid lizards are discussed in light of new data. According to IUCN Red List criteria, the new species is categorized as Critically Endangered due to its range-restricted habitat. 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. Keywords. Cophotis, Lyriocephalus, mtDNA, ND2, syntype, systematics, taxonomy Citation: Karunarathna S, Poyarkov NA, Amarasinghe C, Surasinghe T, Bushuev AV, Madawala M, Gorin VA, De Silva A. 2020. A new species of the genus Ceratophora Gray, 1835 (Reptilia: Agamidae) from a lowland rainforest in Sri Lanka, with insights on rostral appendage evolution in Sri Lankan agamid lizards. Amphibian & Reptile Conservation 14(3) [Taxonomy Section]: 103–126 (e259). Copyright: © 2020 Karunarathna et al. This is an open access article distributed under the terms of the Creative Commons Attribution License [Attribution 4.0 International (CC BY 4.0): https://creativecommons.org/licenses/by/4.0/], which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The offcial and authorized publication credit sources, which will be duly enforced, are as follows: offcial journal title Amphibian & Reptile Conservation; offcial journal website: amphibian-reptile-conservation.org. Accepted: 14 September 2020; Published: 2 October 2020 Offcial journal website: amphibian-reptile-conservation.org Introduction Sri Lanka and the Western Ghats of India are collectively recognized as a biodiversity hotspot, rich in both diversity and endemism among the herpetofaunal assemblages (Bossuyt et al. 2004; Gunawardene et al. 2007). However, this area supports the highest human population density among the world’s biodiversity hotspots (Cincotta et al. 2000; Helgen and Groves 2005). The evolutionary and phylogenetic uniqueness of Sri Lanka’s herpetofauna has been well established (Bossuyt et al. 2004, 2005). Despite its small land area, Sri Lanka is geographically diverse as evidenced by the three peneplains of lowland (< 300 m asl), midland (300–900 m asl), and highland (> 900 m asl), that result in an elevation gradient (Cooray 1967). This geographic variation, in conjunction with variability in annual average precipitation, has resulted in three major bioclimatic zones in Sri Lanka: the dry zone (< 1,000 mm), the wet zone (> 2,500 mm), and the intermediate zone (> 1,500 mm) [Greller and Balasubramaniam 1980]. Further contributing to Sri Lanka’s geoclimatic diversity, three distinct mountain ranges of the Central Highland, Rakwana Hills, and the Knuckles Massif, also occur in Sri Lanka (Gunatileke and Gunatileke 1990; MoE-SL 2012). These geo-climatic variations have generated an array of environmental gradients, creating niche flters that promote speciation, which has led to the great diversity of the herpetofauna in Sri Lanka. The great richness of Sri Lankan herpetofauna can be attributed to insular radiation, reproductive isolation, and high island-wide Correspondence. *suranjan.karu@gmail.com (SK), n.poyarkov@gmail.com (NAP) urn:lsid:zoobank.org:pub:CBE74FDA-A9D0-4957-A2E5-6F29ADD40578