Trimeresurus gracilis Oshima, 1920

Size

Trimeresurus gracilis is a small pit viper with a maximum total length of 60 cm (24 in).

Scalation Pattern

Its scalation pattern includes 19 or 21 rows of dorsal scales at midbody, 144–149 ventral scales, 43–53 subcaudal scales, and 7–8 supralabial scales.

Distribution Range

This species is endemic to Taiwan, where it occurs only at elevations above 2,000 m (6,600 ft) above sea level.

Type Locality

The species' given type locality is "Mt. Noko, Nanto"; Zhao and Adler (1993) identified this location as "Mt. Nôkô, Nanto Co., central Formosa", which corresponds to Mount Nengkaoshan, Nantou County, Taiwan.

Phylogenetic Relationship Contradiction

One phylogenetic study found results that contradicted a common prior inference of a close relationship between Trimeresurus monticola and Trimeresurus okinawensis.

Sister Relationship Finding

Instead, the study suggested that T. okinawensis and T. gracilis share a sister relationship.

Genus Dispersal History

The phylogenetic relationships uncovered in this study also indicate that the genus Trimeresurus dispersed into the Ryukyu region at least three separate times.

Historical Species Distribution

The study also notes that Trimeresurus flavoviridis and Trimeresurus tularensis, both found in the central Ryukyus, were previously more widespread and diverse across surrounding regions than they are today.