Saint Kitts and Nevis
The Saint Kitts Bullfinch Loxigilla portoricencis grandis (Naturalis) is an extinct endemic bird subspecies.
Arthropods known only from Saint Kitts and Nevis include a stick insect Diapherodes christopheri (Phasmida), an undescribed fungus weevil of the genus Ormiscus (p. 9 of Univ. Nebraska pdf file), the tarantulas Nesipelma insulare (theraphosidae.cz) and Cyrtopholis media (BHL), and a ground spider Cesonia maculata (AMNH).
Two species of ferns are the only endemic vascular plants: Thelypteris muscicola (Harvard) and Asplenium malcolm-smithii (JSTOR).
For an overview of the biota see the "Biodiversity Profile of St. Kitts and Nevis" (bio-diversity-nevis.org pdf file).