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| The widespread Ramphotyphlops braminus. JCM |
Blind snakes of the family Typhlopidae number about 250 species and are found throughout the tropical and sub-tropical world in Asia, Africa, Australia, and South America. The family is also well represented in the island archipelagos of Greater and Lesser Antilles, the Philippines, and the Solomon Islands, but its members are mostly unknown in Oceania north of Melanesia and east of Palau. The exception is the flower pot snake, Ramphotyphlops braminus, a parthenogenetic species that has been carried around the world by humans. More than 30 blind snake species have island distributions in the western Pacific, from the Philippines in the north to Fiji in the south. But, only two species are reported from Oceania to the north and east of this arc: Typhlops pseudosaurus from Guam (now regarded as Ramphotyphlops braminus and Ramphotyphlops acuticaudus from Palaua. Ramphotyphlops acuticaudus is similar to Ramphotyphlops flaviventer and related species from Halmahera eastward through New Guinea and the Solomon Islands to Fiji is the only recognized species that occurs inside this island arc, and other than R. braminus, no blind snakes occur eastward in Micronesia. Two recent discoveries suggest blind snakes occur within the Caroline Islands and are possibhly widespread. In 1999, a typhlopid was collected on Pasa Island, Ant Atoll from inside a rotted Cocos trunk that was lying on the ground. Subsequently, the presence of blind snakes on Ulithi, approximately 2000 km to the west of Ant Atoll. Comparison of these specimens from Ant Atoll and Ulithi, along with more recently collected specimens, indicate that they represent two similar undescribed species of Ramphotyphlops. These two snakes have now been described byn Addison Wynn and colleagues (2012).
Ramphotyphlops adocetus is from Ant Atoll, Pasa Island Caroline Islands, and Ramphotyhlops hatmaliyeb is from Giilab Island, Ulithi, Caroline Islands
The authors point out such low-lying atolls as Ant and Ulithi are usually inhabited by widespread, highly adaptable species. Except for Ramphotyphlops adocetus, the terrestrial vertebrate fauna of Ant Atoll is a subset of more broadly distributed species also occurring on Pohnpei, and the reptiles found on Ant Atoll are all species inhabiting many of the Caroline Islands and beyond. The only other reptiles known solely from atolls in the Caroline Islands east of Palau are the geckos Perochirus scutellatus, endemic to (Kapingamarangi Atoll); and P. cf. scutellatus (endemic to Ulithi on Sorenleng Island; Bulbul, Giilab, Iaar, Soong, and Yeew islands) and Lepidodactylus oligoporus, known from only from a single island on Namoluk Atoll.
Pacific atolls, are recent phenomena and form form unconsolidated sand and gravel piled on top an emergent paleoreef, making them only 1000 to 2000 years old, but were built upon the rims of karst platforms exposed when sea levels were as much as 125 m lower during the peak of the last glaciation. Today’s atolls formed after present sea levels were reached after sea level was lowered 1.0 to 2.6 m about two thousand years ago. If the two new blind snakes require stable, perched atolls for habitat, they must have dispersed to Ant Atoll and Ulithi no more than two thousand years ago, possibly from the relatively close high islands of Pohnpei and Yap. But, the snakes remain unknown from those islands at the present time.
Citation
Wynn, A. H, Reynolds, RP, Buden, DW, Falanruw, M., & Lynch, B. 2012. The unexpected discovery of blind snakes (Serpentes: Typhlopidae) in Micronesia: two new species of Ramphotyphlops from the Caroline Islands. Zootaxa 3172:39-54.
Labels: Pacific atolls, Ramphotyphlops
