Dobsonia, a genus of large to medium-sized fruit bats, occurring from Celebes to the Solomon Islands, contains at least nine species. One species and its two subspecies are endemic to the Solomons.
Dobsonia differs from all other genera of megachiropteran bats in the Solomons by combining absence of a small claw on the second digit and presence of external tail vertebrae.
The cranium of Dobsonia resembles, in some ways, the cranium of Rousettus as well as that of Pteropus. Even so, in Dobsonia the rostrum is shorter and the cheek-teeth, especially in the upper jaw, are more crowded. The anterior part of the mandible is narrow and the lower incisors are diminutive and often concealed by the flesh of the gum.
Dobsonia inermis
In a review of the genus Dobsonia, Andersen (1909c:532) named and described D. inermis and D. nesea from the Solomons. Specimens of Dobsonia inermis from San Cristobal and Ugi were said to differ from specimens of D. nesea from Alu, Shortland, and Rubiana in having perpendicular as opposed to anteriorly slanted upper canines. Andersen (1909c:532) reported that the two species were of "... the same general size." Troughton (1936:348-349) studied specimens of Dobsonia from Bougainville and Santa Ysabel and, because of individual variation in proclivity of the upper canines, concluded that D. nesea was conspecific with D. inermis. He (p. 349) noted that the ears were shorter in inermis than in nesea, but the size of teeth showed insular variation and a "... confusing amount of intergradation ... [that obscures] ... diagnostic importance."
Specimens of Dobsonia from Choiseul are smaller (externally and cranially) than those from Alu, Shortland, Rubiana, Bougainville, Fauro, Vella Lavella, Guadalcanal, Florida, Ugi, San Cristobal, and Rennell. Specimens from Santa Ysabel (see [Fig. 8]) are intermediate in size between those from Choiseul and the other islands listed. Judging from available specimens, two subspecies of Dobsonia inermis occur in the Solomons. Specimens from Choiseul (see A, [Fig. 8]), which are smaller than those from other islands, represent one subspecies (heretofore unrecognized), whereas specimens from other islands (except Santa Ysabel) represent a second subspecies. Specimens from Santa Ysabel are slightly larger than those on Choiseul and are regarded as intergrades between the two subspecies. Specimens from Rennell, Ugi, San Cristobal, Florida, Fauro, and Guadalcanal are slightly smaller than those from Bougainville, Vella Lavella, Shortland, and Rubiana, but the differences are not great enough to warrant recognition of two subspecies. Therefore, the subspecific name nesea is arranged as a synonym of inermis, which has priority, and the latter name is used for specimens of Dobsonia inermis from the Solomon islands other than Choiseul and Santa Ysabel. Additional remarks on the distribution of this species are in the section on Zoogeography and Speciation.
Pohle (1953:130) suggested that Dobsonia inermis (as well as D. crenulata and D. praedatrix) is conspecific with D. viridis, but Laurie and Hill (1954:41) did not adopt his suggestion. I have not seen adequate series of crenulata, praedatrix, and viridis (none of which occurs in the Solomons) to judge systematic relationships of these kinds; therefore I follow Laurie and Hill.
Dobsonia inermis inermis Andersen
1909. Dobsonia inermis Andersen, Ann. Mag. Nat. Hist., ser. 8, 4:532, December, type from San Cristobal; 1912, Andersen, Catalogue of the Chiroptera ... British Museum, 1:475.