2001 Asiatic Herpetological Research Vol. 9, pp. 9-22 A New Snake of the Genus Ho/ogerrhum Gur\\her (Reptilia; Squamata; Colubridae) from Panay Island, Philippines Rafe M. Brown 1 -2 , Alan E. Leviton 3 , John W. Ferner 2 -4 , and Rogelio V. Sison 5 Section of Integrative Biology (C0930) and Texas Memorial Museum, University of Texas, Austin, Texas, 78712, USA. e-mail: [email protected]; Geier Collections and Research Center, Museum of Natural History and Science, 1301 Western Avenue, Cincinnati, Ohio 45203; -Department of Herpetology, California Academy of Sciences, San Francisco, California 94118, USA. e-mail: [email protected]; Department of Biology, Thomas More College, Crestview Hills, Kentucky, 41017, USA. e-mail: [email protected]; Herpetology Section, Zoology Division, National Museum of the Philippines, Executive House, P. Burgos Street, Manila, Philippines, e-mail: [email protected] Abstract.-We describe a new species of snake in the genus Hologerrhum from two forested localities in Antique Province, Panay Island, Philippines. To clarify species boundaries, we also redescribe its only known congener, H. philippinum, on the basis of historical collections and newly-acquired material from the Islands of Luzon, Marinduque, Polillo, and Catanduanes. The new species is the first Hologerrhum from the Visayan Aggregate Island Complex and differs from Hologerrhum philippinum in color pattern and scalation of head and body. The new species is one of several recently described vertebrates from Panay Island. Together, they indicate that forested regions of the individual islands of the Visayan Aggregate Island Complex (Negros, Panay, Cebu. Masbate, and other associated smaller islands) contain low levels of taxonomic endemicity that warrant further study. Key words.-Colubridae, Hologerrhum, Philippines, Panay Island, Visayas. Introduction Giinther (1858) erected the monotypic genus Holo-gerrhum to accommodate a single specimen from Hugh Cuming's Philippine collections that had been deposited in the Natural History Museum, London (Giinther, 1873; Fig. 1A). Giinther distinguished the new genus and species from members of the Philip-pine genus Cyclocorus by the presence of slight grooves in the enlarged fang-like teeth at the posterior end of the maxilla. Other slight differences between Hologerrhum and some species of Cyclocorus, not emphasized by Giinther but mentioned by other work-ers (Taylor, 1922a, 1922b; Leviton, 1965). include color pattern, slight scale pattern differences, and less strongly enlarged middle series of maxillary teeth in Hologerrhum. At the time of the description of Hologerrhum, no specific (island) locality data were available, but Giinther later (1879) referred a specimen from Placer, northeast Mindanao Island to this species. That speci-men (not seen by us) apparently is a representative of the genus Cyclocorus Taylor 1922c (vide Boulenger, 1896; see also comment by Taylor, 1 922a: 1 16). Jan and Sordelli (1870) described Cyclochorus maculatus (generic name misspelled), on the basis of a specimen reportedly from Java Island, Indonesia (Fig. IB). Fischer (1885) followed by recognizing Cyclochorus lineatus var. maculatus reportedly from S. Mindanao Island, Philippines, but without refer-ence to new material. The type specimen of Cyclocho-rus maculatus later was shown to be a representative of H. philippinum (Giinther, 1873. 1879; Boettger, 1886; Taylor, 1922a), suggesting locality errors by both Jan and Sordelli and Fisher. Later, Leviton (1965) inadvertently included Cyclochorus maculatus in the synonymy of Cyclochorus lineatus. Castro de Elera (1895) reported Hologerrhum philippinum from Baco, Mindoro Island. This impor-tant specimen could not be examined as it was destroyed during dissections by a biology class at the University of Santo Thomas, Manila (R. I. Crombie, personal communication) but the "Mindoro" locality information suggests a misidentification of a speci-men of C. lineatus (Taylor, 1922a; Leviton. 1963, 1965). Griffin (1910) did not include Hologerrhum in his list of snakes from Polillo but did include the spe-cies in his key to the Philippine snakes (Griffin, 191 1), although he erred in attributing the type description to Boulenger and supplied no precise locality data.