HERPETOFAUNA OF THE PACIFIC COAST OF NORTH CENTRAL BAJA CALIFORNIA, MEXICO, WITH A DESCRIPTION OF A NEW SUBSPECIES OF PHYLLODACTYLUS XANTI DENNIS L. BOSTIC ABSTRACT.— Three species of lizards are recorded from the Pacific slope of Baja California, Mexico, for the first time: a leaf-toed gecko, Phvllodactylus xanti sloani n. subsp., Crotaphvtus collaris and Sauromalus australis. The distribution, pattern, and scutellation of Gerrhonotus multicarinatus spp. indicates a south-ward expansion of its range since glacial maxima via the cool, moist, coastal corridor, and its possible in-tegradation with G. paucicarinatus. A southward coastal corridor diff"usion may also be true for Tantilla planiceps eiseni, Coleon vx variegalus abbot ti and Lichanura roseofusca gracia. Of the 29 species of amphibi-ans (2), lizards ( 16), and snakes (11) collected, only one lizard, Cnemidophorous labialis, is considered en-demic to the Central Desert of Baja California. Homogeneity of habitats, the moderate climate and the extir-pation of the Peninsular desert herpetofauna during glacial maxima probably have been important factors in reducing or limiting species diversity and endemism. INTRODUCTION The coastal deserts of North America, of which more than 2000 miles are confined to Baja California and Sonora, Mexico, remain biologically unknown because of their relative inaccessibility, lack of potable water, and rugged terrain. Wiggins (1960a) identified these and other regions in Baja California as in need of more careful biological exploration. One area he mentioned was the Pacific coastal region between El Rosario (30°N) and the south-ern boundary of the state of Baja California (28°N; Fig. 1). Excluding the immediate areas of El Rosario and Rosarito, where the main road approaches within ten miles of the ocean, this region has not been explored herpetologically. In the spring and summer of 1969, 1 made several trips (Table 1) into the area in order to: 1) better ascertain the distributional limits of the herpetofauna, 2) gather ecological data; and 3) collect specimens for studies of geographical variation and evolution. METHODS AND MATERIALS A Taylor sling psychrometer and a Dwyer wind gauge (0-60 mph) were used to meas-ure relative humidity and wind speed. A Taylor soil thermometer (0-50°C) and a multi-channel tele-thermometer unit were used to record soil (approximately 0.5cm beneath surface) and air temperatures (approximately 0.5cm above surface). Time (Standard) is ex-pressed in 24 hour fashion. Throughout this paper when counts or measurements are pre-sented in the following manner: 1 1 ±1.3(10-12)18, the first figure refers to the arithmetic mean, the second figure to the standard error of the mean, the figures in parentheses to the range, and the last figure to the number of observations. Occasionally, the standard error of the mean is omitted, but the order, with this exception, remains the same. Standard devia-tion is indicated by S.D. All snout-vent measurements have been rounded off to the nearest whole number and other measurements to the nearest tenth. Within each major systematic grouping the species are arranged alphabetically by genus. I have not been consistent in the treatment of subspecies and have omitted available trinomials where geographical variation is poorly known. All material collected has been deposited in the collections of the San Diego Society of Natural History. SAN DIEGO see. NAT. HIST., TRANS. 16 ( 10): 237-264, 25 AUGUST I97I
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