Part 15

1904. Carponycteris nana (part), Trouessart, Catalogus Mammalium ..., Suppl., p. 65.

1907. Kiodotus sp., Miller, Bull. U. S. Nat. Mus., 57:70, June 29.

1936. Odontonycteris lagochilus microtus, Troughton, Rec. Australian Mus., 14:350, April 7, from Bougainville.

Specimens examined (14 males and 16 females; in alcohol).--Choiseul in March, 23654-57, 23614, 23629, 23643, 23645, 23647, 23677-79, 23684; Vella Lavella in December, 23277-79, 23283-84; Fauro in April, 23765; Guadalcanal in May and June, 23830, 23864, 23935; Kolombangara in January, 23385, 23399, 23397, 23407, 23420-21; Santa Ysabel in June, 24067; Malaita in June, 24067.

Measurements.--Average and extreme external measurements of 14 males and 15 females are as follows: Length of head and body, 68.3 (63-72); tail vertebrae present but scarcely perceptible and therefore not measured; hind foot, 11.4 (9.0-12.9); ear, 12.0 (10.0-12.9); length of forearm, 37.6 (36.2-39.9).

Remarks.--The distribution of Macroglossus lagochilus microtus has not been well known. Specimens herein reported from Choiseul, Fauro, and Vella Lavella provide new records of distribution. As shown on Figure 10, the subspecies occurs throughout the Solomon Islands.

Macroglossus lagochilus microtus differs slightly from M. l. nanus Matschie, the subspecies of the Bismarck Archipelago and Admiralty Islands to the north of the Solomons. M. l. nanus averages slightly larger than microtus (see Andersen, 1912:768-769, for comparative measurements) but otherwise closely resembles it.

Individual variation is evident in several measurements of the specimens at hand (in length of forearm, for example) but no clines are apparent. Four females obtained in March were lactating, as was one taken in December and one taken in January.

=Melonycteris= Dobson

1877. Melonycteris Dobson, Proc. Zool. Soc. London, p. 119, June 1.

1877. Cheiropteruges Ramsay, Proc. Linn. Soc. New South Wales, 2:19, July.

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

=Melonycteris aurantius= Phillips

1966. Melonycteris aurantius Phillips, Jour. Mamm., 47:23-27, March 12, type from Florida Island, additional specimens from Choiseul Island.

Specimens examined (six females; three in alcohol).--Florida in October, 24440; Choiseul in March, 23615, 23617, 23558, 23694, 23681.

Measurements.--Average and extreme measurements of six females are as follows: Length of head and body, 80.8 (77-106); hind foot, 17.2 (16.0-18.7); ear, 12.7 (11.5-14.0); length of forearm, 49.3 (42.9-53.8). Average and extreme measurements of skulls of five females are as follows: Greatest length of skull, 31.8 (30.8-33.3); condylobasal length, 29.7 (28.6-32.4); zygomatic breadth, 18 (17.2-20.0); breadth of braincase, 12.6 (12.4-13.2); postorbital breadth, 8.3 (8.0-8.9); length of maxillary tooth-row, 10.1 (9.4-10.4); length of mandibular tooth-row, 11.7 (10.8-12.2).

Remarks.--On Choiseul Island Melonycteris aurantius was taken at the same locality as its congener, Melonycteris woodfordi.

Externally, M. aurantius resembles M. woodfordi. These species are the same size, but the former is brighter in color (nearly orange in adults) than the latter, which is Wood-Brown dorsally. Internally, differences between M. aurantius and M. woodfordi are more obvious. In the skull of M. aurantius, the postorbital region is expanded (measuring about 8.3), whereas in M. woodfordi the postorbital region is constricted. Furthermore, in lateral aspect the posterior portion of the skull of M. aurantius is down-turned and the angle of the facial axis with the basicranial axis is much more acute than in M. woodfordi.