===========+========+==========+===========+============+=============== | | | Common | Common to | Common to | | Endemic | only to | Solomons, | Solomons, | Totals | to | Solomons | Bismarcks, | New Hebrides, | | Solomons | and | and | and | | | Bismarcks | New Guinea | New Caledonia -----------+--------+----------+-----------+------------+--------------- Genera | 7 | 1 | 0 | 6 | 0 Species | 16 | 9 | 1 | 6 | 1 Subspecies | 20 | 19 | 0 | 0 | 1 -----------+--------+----------+-----------+------------+--------------- The megachiropteran bats of the Solomons have their affinities with the fauna of New Guinea (Table 4); the Solomons and New Guinea have six genera and six species in common. Because the two areas never have been connected (_via_ the Bismarck Archipelago) by dry land, bats probably have reached the Solomons by flying from island to island (see Durham, 1963:357, 359, 361, 363). Deignan (1963:266) has dismissed voluntary or involuntary flight as possible explanations for distributions of bats and birds on islands of the Pacific. The taxonomic level of endemism can be used as an indicator of antiquity (Dobzhansky, 1941; Koopman, 1958:429-430). The one megachiropteran genus (_Pteralopex_) endemic to the Solomons apparently is an ancient relic. Bats of this monotypic genus occur on Bougainville, Choiseul, Santa Ysabel, and Guadalcanal (see Fig. 4). These four islands probably were contiguous during the maximum lowering of sea level in the Pleistocene (see Durham, 1963:362-363). Bats of the genus _Pteralopex_ are the only kind in the Solomons having a distribution that can be correlated with former land connections between islands. The distributions of 16 species of megachiropterans known from the Solomons are summarized in Table 5 and in Figure 16. The larger islands (in terms of surface area and elevation) in general have the highest number of species (Guadalcanal 10, Choiseul 9, and Bougainville 8). But Fauro, one of the smallest islands for which data are available, has six species of megachiropterans whereas San Cristobal and Malaita, two of the larger islands, have only three and four species, respectively. Possibly this difference signals the need for additional collecting.