Part 7

Andersen (1909a:216; 1912:436) considered the relationships of Pteralopex and Pteropus and concluded that Pteropus pselaphon Lay, 1829, from the Sulphur Islands east of Taiwan, and Pteropus samoensis Peale, 1848, from the Samoan Islands, were the "closest" living relatives of Pteralopex. He stated further that Pteralopex "presents in fact scarcely a single character which is not either developed to a certain extent or at least distinctly foreshadowed in Pteropus pselaphon, pilosus, tuberculatus, or leucopterus." In summary, Andersen thought several species of Pteropus had undergone evolutionary development resembling that in Pteralopex, and that the latter, with its massive, cuspidate cheek-teeth, could be considered a highly modified Pteropus. For this hypothesis to be plausible, one must assume that the originally complex cheek-teeth of pteropodids became simple and, at least in the case of Pteralopex, secondarily became complex once again. According to present-day theory of evolutionary development, his hypothesis is improbable. Thomas (1888b:475) probably was correct when he considered Pteralopex an isolated relic.

Although Pteralopex usually is listed after Pteropus in phylogenetic arrangements (see, for example, Sanborn, 1931:21; Pohle, 1953:129; Laurie and Hill, 1954:40), I have placed Pteralopex before Pteropus.

=Pteralopex atrata=

Two subspecies of Pteralopex atrata (P. a. atrata and P. a. anceps) have been named; specimens of both are rare in museum collections. Thomas (1888a:155) described adults of atrata. Sanborn (1931:21) examined the one additional specimen known to me and reported that it agreed with Thomas' description.

Andersen (1909b:266) used a subadult female ("nearly fully grown") as the holotype of anceps. At least five additional specimens, all adults, of anceps now are housed in various collections. Judging from these individuals, the holotype of anceps was only four-fifths grown and because he used an immature individual, Andersen's (1912:437) criteria for distinguishing the two subspecies mostly are invalid.

Key to Subspecies of Pteralopex atrata

1. Length of forearm 139-144 mm.; dorsal surface of distal one-fourth of tibia and entire metatarsus naked; known only from Guadalcanal and Santa Ysabel islands Pteralopex atrata atrata

1'. Length of forearm 162-166 mm.; dorsal surface of distal one-fourth of tibia and entire metatarsus furred; known only from Bougainville and Choiseul islands Pteralopex atrata anceps

=Pteralopex atrata atrata= Thomas

1888. Pteralopex atrata Thomas, Ann. Mag. Nat. Hist., ser. 6, 1:155, February, type from Guadalcanal; 1888, Thomas, Proc. Zool. Soc. London, p. 475, December 4; 1896, Heude, Mém. Hist. Nat. Emp. China, 3:179; 1897, Trouessart, Catalogus Mammalium ..., 1:83; 1907, Miller, Bull. U. S. Nat. Mus., 57:60, June 29; 1912, Andersen, Catalogue of the Chiroptera ... British Museum, 1:439; 1931, Sanborn, Publ. Field Mus. Nat. Hist., Zool. Ser., 18:21, February 12, from Santa Ysabel.

1954. Pteralopex atrata atrata, Laurie and Hill, List of land mammals of New Guinea, Celebes and adjacent islands, p. 40, June 30.

1899. Pteropus (Pteralopex) atrata, Matschie, Die Megachiroptera ... naturkunde, p. 11; 1904, Trouessart, Catalogus Mammalium ..., Suppl., p. 49.

Specimens examined.--None.

Remarks.--Pteralopex atrata atrata is known from four specimens from Guadalcanal and one from Santa Ysabel (Sanborn, 1931:21).

Sanborn (loc. cit.) reported that a specimen wounded at night, while feeding on young green coconuts, was the only fruit bat that attempted to attack the collectors. Troughton (1936:348) has suggested, on the basis of his experiences with Pteropus, that this behavior probably was a reaction from fear rather than an indication of general aggressiveness on the part of Pteralopex.

=Pteralopex atrata anceps= Andersen

1909. Pteralopex anceps Andersen, Ann. Mag. Nat. Hist., ser. 8, 3:266, March, type from Bougainville; 1912, Andersen, Catalogue of the Chiroptera ... British Museum, 1:437; 1936, Troughton, Rec. Australian Mus., 14:348, April 7; 1953, Pohle, Z. Säugetierk., 17:129, October 27.

1954. Pteralopex atrata anceps, Laurie and Hill, List of land mammals of New Guinea, Celebes and adjacent islands, p. 40, June 30.

Specimens examined (three males, two females; one skull-only and one in alcohol).--Choiseul in March, 23682; Bougainville in July, USNM 276973-74, USNM 276928, USNM 277112.

Measurements.--Measurements of three males and one female are, respectively, as follows: Length of head and body, 280, 271, 261, 255; hind foot, 50, 54, 52, 59; ear, 23, 23, 26, 22; length of forearm, 160, 162, 166, 171; greatest length of skull, 77.6, 77.9, 78.9, 77.0; condylobasal length, 74.3, 74.3, 75.5, 73.8; zygomatic breadth, 42.2, 45.4, 43.1, 42.6; breadth across upper canines, 18.7, 21.1, 19.0, 19.0; breadth across first upper molars, 22.2, 25.3, 22.9, 22.0; length of maxillary tooth-row, 29.3, 29.8, 28.9, 28.2; length of mandibular tooth-row, 32.8, 32.8, 32.1, 31.4.

Remarks.--Heretofore, Pteralopex atrata anceps was not known from Choiseul. The specimen from that island agrees well with specimens in the U. S. National Museum from Cape Torokina, Bougainville.

The type specimen of this subspecies is a subadult and is smaller than the specimens examined by me; Andersen (1912:440) gave length of forearm of the type as 137 (as opposed to 164 in adults). He (1912:438) figured the dentition of anceps and described the ways in which it differed from the dentition of atrata. Although he (1912:437) concluded that anceps and atrata represented "two stages of specialization of ... dentition," there apparently are few, if any, dental differences between the two subspecies. Teeth of adults of anceps differ from teeth of the immature type of anceps as follows: in adults the anterior basal ledge of P4 extends onto the labial surface, whereas in the type it does not; and maxillary and mandibular teeth in adults are spaced as in the subspecies atrata (see Andersen, 1912:438, fig. 22) and not crowded as in the type of anceps. Distance between individual cheek-teeth apparently increases with growth of the cranium and mandible.

Adults of P. a. anceps that I examined are darker than the subadult type. The mantle in these adults is black, whereas it is seal-brown in the type (Andersen, 1912:439).

An adult female was lactating when obtained on Bougainville in July (USNM 276928).

Key to Pteropus in the Solomon Islands

1. Premolars having distinct basal ledges; molars 2.5-4.0 wide 2

1'. Premolars lacking definite basal ledges; molars 1.0-2.4 wide 14

2(1). Rostrum unshortened (orbit to anterior tip of nasals about one-third greatest length of skull); dorsal surface of tibiae nearly naked 3