P4-5 Sat Jan 2 Smaller, smaller, and smaller Heide, OA*; Perez, CA; Herrera-Martínez, A; Thomas , R; Daza, JD; Sam Houston State University, Huntsville, TX; University of Missouri, Columbia, MO; Sam Houston State University, Huntsville, TX; University of Puerto Rico, Río Piedras, Puerto Rico; Sam Houston State University, Huntsville, TX oah003@shsu.edu https://geckolab.weebly.com
The Puerto Rican Crescent gecko (Sphaerodactylus nicholsi) has a disjunct coastal distribution, including North coast and South Coast populations. This is the smallest gecko species from Puerto Rico. Here we measured specimens from both populations and compared measurements (snout to vent length [SVL], and skull length [SL]). Measurements were taken from digital X-rays obtained with a Thermo Scientific™ Micro Focus system and Digital X-Ray Detector using ImageJ. We ran Wilcoxon rank sum test using the North and South populations and found marked differences in SVL (W = 87, p-value = 0.02338) and SL (W = 90, p-value = 0.02787) between the North (Mean SVL=23.38 mm ± 1.95, Mean SL = 6.00 ± 0.26, n=5) and South populations (Mean SVL=20.95 ± 1.39, Mean SL= 5.57 ± 0.36, n=22). Specimens from Punta Verraco are extremely small, being comparable to the smallest amniote (S. ariasae) from Isla Beata in Hispaniola. We also review similarities between these miniaturized species, using HRCT data of one individual from S. nicholsi and S. ariasae. The skull of S. nicholsi is about 1.2 times the size of one of the smallest specimens of S. ariasae. With only 1 mm difference, both skulls look very similar, but S. nicholsi has a narrower frontoparietal suture, and proportionally longer jugal bones. S. ariasae shows an open prootic foramen (unique to gekkotans). This study indicates that Sphaerodactylus geckos from coastal and very dry areas tend to attain record small size. A revision of microhabitat for other miniaturized geckos is needed, and a comparison of their cranial anatomy, to determine if the observed traits have evolved multiple times.
