Viquez’s Tropical Ground Snake was described in 1937; it is known exclusively from the type that was found in 1927 somewhere in the Siquirres District in the north-eastern part of Costa Rica.
The species has never been found since and given the fact that the type locality has severely suffered from loss of native vegetation, it might indeed be extinct.
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edited: 21.08.2022
Alfaro’s Hummingbird (Amazilia alfaroana)
Alfaro’s Hummingbird was described in 1896, it is known from a single specimen that had been collected at the Volcán de Miravalles in northwestern Costa Rica; it was mostly treated as a subspecies of the Indigo-capped Hummingbird (Amazilia cyanifrons (Bourcier)) which, however, is endemic to Colombia.
The sole specimen was analysed at least two times, in both cases with the same result: it is a distinct species. [1][2]
Alfaro’s Hummingbird is now accepted as a full species and is considered extinct.
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References:
[1] André-Alexander Weller: On types of trochilids in the Natural History Museum, Tring III. Amazilia alfaroana Underwood (1896), with notes on biogeography and geographical variation in the Saucerottia saucerrottei superspecies. Bulletin of the British Ornithologists’ Club 121(2): 98-107. 2001
[2] Guy M. Kirwan; Nigel J. Collar: The ‘foremost ornithological mystery of Costa Rica’: Amazilia alfaroana Underwood, 1896. Zootaxa 4189(2): 244-250. 2016
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edited: 30.10.2020