PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON I12(3):510-514. 1999. A new species of Platymantis (Amphibia: Ranidae) from the Sierra Madre Mountains, Luzon Island, Philippines W. C. Brown, A. C. Alcala, P. S. Ong, and A. C. Diesmos (WCB) Department of Herpetology, California Academy of Sciences, San Francisco, California 94118, U.SA.; (ACA) Conomission on Higher Education, DAP Bldg., San Miguel Avenue, Pasig City, Philippines; (PSO) Institute of Biology, University of the Philippines, Diliman, Quezon City, Philippines; (ACD) College of Arts and Sciences, University of the Philippines Los Bafios College, Laguna, Philippines Abstract. — A new species, Platymantis sierramadrensis, from the Sierra Ma-dre Mountains in the provinces of Aurora and Isabela, Luzon Island, Philip-pines, is described. This species is distinguished from other Philippines species of Platymantis (hazelae group) by its pale color, smooth skin, advertisement call, and other characters given in the diagnosis. Recent field work in the Sierra Madre Mountains, northeastern Luzon Island, con-ducted separately by us in 1996 and 1997 resulted in the collection of 22 specimens (16 adults and 6 juveniles) of this distinc-tive frog. These specimens are platymantine frogs based on structure of the pectoral gir-dle (Brown 1952) and are referred to the hazelae group of Platymantis based on dig-ital structures (Brown et al. 1997). This spe-cies is an addition to the list of eight other species occurring on Luzon and the Central and Western Visayas and currently assigned to this group. The specimens are deposited in the California Academy of Sciences (CAS) and Philippine National Museum (NMPH). Materials and Methods Materials examined included holotypes of all other species of the hazelae group of Platymantis from the Philippines. These ho-lotypes with the exception of P. panayensis are in the CAS collections. The holotype of P. panayensis is in the NMPH. Morphometric characters. — Snout-vent length (SVL), head length (HL), head breadth (HW), snout length (SnL), diameter of eye (ED), diameter of tympanum (TD), tibia length (TiL), third finger length from proximal edge of basal tubercle (3FL), di-ameter of third finger disk (3FD), and di-ameter of third toe disk (3ToD). Advertisement calls (Fig. 1) were record-ed and analyzed, using a Kay Electrics SonaGraph (Model #550) and SIGNAL Sound Analysis System software. Platymantis sierramadrensis, new species Fig. 2 Holotype. — NMPH 6465, an adult fe-male, collected by Marisol Pedregosa in disturbed lowland forest at Sitio Mapidjas, Barangay Umiray, Municipality of General Nakar, Quezon Province, Luzon Island on 29 May 1996. Paratypes.— CAS 204738, 204742-45 and NMPH 5980, 6461-63, 6466-67, CMNH 05678-79, collected in disturbed lowland forest in Sitio Mapidjas, Barangay Umiray, Municipality of Dingalan, Aurora Province, Luzon Island at the southern end of the Sierra Madre mountains. Referred specimens. — CAS 204739-41 and NMPH 6464, 6470-74 from Palanan, northern Sierra Madre Mountains, Isabela Prov., Luzon Island. These specimens are in close agreement morphologically and in
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