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The small Caribbean island of Navassa (U.S. possession) is unoccupied by humans, but recent surveys have detected a surprising number of endemic (precinctive) invertebrates. A new species of May beetle, Phyllophaga navassa, is here described and compared to the Hispaniolan Phyllophaga fauna.
The large genus Phyllophaga Harris is estimated to contain over 500 species (Morón 1997:229); perhaps the largest genus of New World Scarabaeidae. In the recent revision of the species for the island of Hispaniola (Woodruff and Sanderson 2004), 48 species were treated, of which 22 were described as new. All 48 are endemic only to Hispaniola, and many have restrictive distributions within the island. The Island of Navassa lies only 56 km west of the tip of Haiti, so it was somewhat surprising to learn that this endemic new species was abundant there. Discovery of these, and a narrative of the survey of the island, was documented by Steiner and Swearingen (1998, 2000), and Swearingen (1999). They reported collecting more than 600 terrestrial arthropod morphospecies, estimated to be 30% endemic. Additional information on habitat was provided by Nearns and Steiner (2006) in the description of a new species of Plectromerus Haldeman (Cerambycidae), and by Steiner (2008) in a report on Carabidae known from the island. The island has been a U.S. possession since 1856, when it was claimed under the “Guano Act”, and it was mined for phosphates during the latter part of the 19th century. The U.S. Coast Guard operated a lighthouse there from 1929 to 1996. It was acquired by the U.S. Department of Interior, and in 1999 it was designated as the Navassa National Wildlife Refuge under the U.S. Fish and Wildlife Service. The herpetology of the island was treated by Powell (1999). The island is only 5 kilometers square, with no beaches, and abrupt cliffs reaching heights of 20 meters. The central forest is about 70 meters elevation, where many specimens were collected. The geology was studied by Burne, Horsfield, and Robinson (1974), and the island was estimated to be 2-5 million years old, but never connected to another larger landmass. This isolation would explain much of the endemism found. It is composed of Eocene limestone with rugged karst surface and red oolitic soil (reminiscent of the bauxite areas near Cabo Rojo in the Dominican Republic). It has a significant forest cover, dominated by 4 species of tropical trees: Sideroxylon foetidissimum Jacquin, Ficus populnea Wildenow var. brevifolia (Nuttall) Warb., Coccoloba diversifolia Jacquin,