Costa Rica Water Snake

Hydromorphus concolor (Peters 1859)

Hydromorphus concolor (Peters, 1859) Morphology. We support the two morphological variations proposed by Savage and Donnelly (1988; Fig. 1 A, B) and highlight the presence of an enlarged loreal scale in contact with both the eye and the upper preocular scale as an important character (Fig. 1 C). We examined 13 specimens (11 live and two in collections). In Panama, only the variant illustrated in Figs 1 B, 2 A, 2 B was observed. Distribution. Type locality: Agua Clara, Chagres River, Colón Province. The species is distributed at low to moderate elevations, from Guatemala to central Panama (Villa 1990; Savage and Donnelly 1988). In Panama, it has been recorded in Colón Province (Fuentes et al. 2023), Panamá Oeste Province (Ibáñez et al. 1996; Ray and Ruback 2015), Panamá Province (Barrio- Amorós et al. 2023), and Santa Fe National Park, Veraguas Province (Lotzkat 2014). We report the species for the first time from the Ngäbe-Buglé Comarca (Ciénaga Mono, 8.4867°N, 81.6850°W) and Coclé Province (Petaquilla, 8.7889°N, 80.6509°W; Fig. 3, Suppl. material 1). Ecology and ethology. Hydromorphus concolor is a predominantly nocturnal and semiaquatic species; it inhabits small streams

Morphology, ethology, new records, and ecological niche modeling for Hydromorphus and Tretanorhinus (Squamata, Colubridae) in Panama