Part 2 (2/2)

8

0 February

6

0

--

1 March

16

1

0

9 April

2

2

0

0 June

1

1

0

0 -----------+-----------+--------------+-----------+-------------

As shown in Table 1, adult females obtained in December and January were lactating when captured whereas those obtained in March, April, and June were not. More than half of the individuals collected in March were immature (judging from small size, unfused epiphyses, and lack of wear on teeth). The immature individuals probably had been nursing in December and January.

=Pteralopex= Thomas

1888. _Pteralopex_ Thomas, Ann. Mag. Nat. Hist., ser. 6, 1:155, February 1.

1762. _Pteropus_ Brisson, Regnum animale ..., ed. 2, p. 153.

_Pteralopex_, with one species and two subspecies, is the only megachiropteran genus endemic to the Solomons. Thomas (1888b:475) considered this unusual bat a relic, isolated from the time when pteropodids had cuspidate cheek-teeth. Although two workers (Matschie, 1899:11; Simpson, 1945:54) have synonymized _Pteralopex_ with _Pteropus_, I regard _Pteralopex_ as a morphologically distinct genus.

Individuals of _Pteralopex_ can be distinguished from all species of _Pteropus_ in the Solomon Islands by the following features: wing membranes originate along dorsal midline; braincase diminutive relative to rest of skull; sagittal crest p.r.o.nounced; cheek-teeth cuspidate, broad and ma.s.sive; i2 about 10 times larger than i1; upper canines with well-developed secondary cusp; pos...o...b..tal process fused with zygomatic arch, forming complete bony ring around orbit.

Andersen (1909a:216; 1912:436) considered the relations.h.i.+ps 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 ma.s.sive, cuspidate cheek-teeth, could be considered a highly modified _Pteropus_. For this hypothesis to be plausible, one must a.s.sume 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 (1888_a_: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 (1909_b_: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 distinguis.h.i.+ng the two subspecies mostly are invalid.

[Ill.u.s.tration: FIG. 4. Distribution of _Pteralopex atrata_; _P. atrata atrata_ ([RW]) and _P. atrata anceps_ ([BC]).

For names of islands see Fig. 2.]

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 Guadalca.n.a.l 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 Guadalca.n.a.l; 1888, Thomas, Proc. Zool.

Soc. London, p. 475, December 4; 1896, Heude, Mem. 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.

<script>