1887. Nesonycteris Thomas, Ann. Mag. Nat. Hist., ser. 5, 14:147, February.
The genus Melonycteris is known from three species, two apparently endemic to the Solomon Islands and the third occurring in eastern New Guinea and the Bismarck Archipelago (Laurie and Hill, 1954:45).
Heretofore, the generic name Nesonycteris has been applied to the species in the Solomons, whereas Melonycteris has been restricted to the one species in the Bismarck Archipelago and New Guinea. Andersen (1912:792) judged that Nesonycteris was clearly distinct from Melonycteris on the basis of two characters (loss of a claw on the second digit and loss of the inner, lower incisors). On the other hand, he noted striking similarities in general cranial features, dentition, palatal ridges, tongue, and external appearance of the two genera. Pohle (1953:131) synonymized the two but Laurie and Hill (1954:45) considered them distinct. I have suggested previously (Phillips, 1966:26, 27) that characteristics used to distinguish between Melonycteris and Nesonycteris are of less than generic value. Variability of number of incisors in the upper jaw of specimens of Melonycteris (and in other macroglossine genera, as well) indicates a lack of selective pressure for either increase or decrease in number of incisors. Furthermore, the loss of the small claw on the second digit might not be important because, as Bader and Hall (1960:15) have pointed out, limbs of bats vary more in phenotypic expression than do other parts of the skeletal structure.
The discovery of a new species (Melonycteris aurantius) in the Solomon Islands sheds additional light on the problem. Although M. aurantius possesses the distinguishing characteristics of the genus "Nesonycteris," the species closely resembles Melonycteris in other features. Similarity in structure of hair of Melonycteris and Nesonycteris, as first reported by Benedict (1957:293), also supports the argument for synonymy (see Phillips, 1966:26).
Melonycteris aurantius lacks a small claw on the second digit and has only two lower incisors. In these ways this species is like woodfordi, which also is restricted to the Solomons. On the other hand, the structure of the skull of M. aurantius is like that of M. melanops, which is the species found in the Bismarck Archipelago.
Although melanops is not yet known from the Solomon Islands, I have included it in the following key.
Key to Known Species of Melonycteris
| 1. | Ventral surface darker than dorsum, but not strongly contrasting with it; lacking a small claw on the second digit, |
| 2 | |
| 1´. | Ventral surface nearly black, strongly contrasting with dorsum; small claw on second digit, |
| Melonycteris melanops | |
| 2(1´). | Pelage bright, Cinnamon-Rufous; postorbital region of skull expanded (about 8.3 wide), |
| Melonycteris aurantius, [p. 816] | |
| 2´. | Pelage dark, near Wood-Brown or Cinnamon; postorbital region of skull constricted (about 7.5), |
| Melonycteris woodfordi, [p. 816] | |