Systematics of Megachiropteran Bats in the Solomon Islands Part 8

Numerous generic names have been applied, at one time or another, to bats now considered as _Macroglossus_. Trouessart (1904:65) and Miller (1907:70) listed the one bat of this genus occurring in the Solomons under _Carponycteris_ and _Kiodotus_, respectively. Andersen (1911:642; 1912:767) and, later, Sanborn (1931:22) identified this bat as _Macroglossus lagochilus microtus_. Troughton (1936:350), reporting an extension of range of this species in the Solomons, used the generic name _Odontonycteris_ without explanation. Andersen (1912:754) pointed out that Jentink originally established the name _Odontonycteris_ on the basis of an extra premolar in each upper jaw as opposed to the usual two in _Macroglossus_, and arranged _Odontonycteris_ as a synonym of _Macroglossus_ because "in no genus of Megachiroptera are dental anomalies of so frequent occurrence as in _Macroglossus_, and on no point of the jaws are these anomalies ... so often met with as on that occupied by the molar series." Sanborn (1931:22) and Phillips (1966:27) noted variation in number of incisors in _Macroglossus_ as well as in _Melonycteris_, another macroglossine genus. All of the more recent workers (Ellerman and Morrison-Scott, 1966; Pohle, 1953; Laurie and Hill, 1954) use the name _Macroglossus_.

=Macroglossus lagochilus=

_Macroglossus lagochilus_ has at least three subspecies, one of which is endemic to the Solomons. The species ranges from Celebes on the west to the Solomon Islands on the east, occurring not only in New Guinea but also on many of the small adjacent islands (see Laurie and Hill, 1954:44).

[Ill.u.s.tration: FIG. 10. Distribution of _Macroglossus lagochilus microtus_. For names of islands see Fig. 2.]

=Macroglossus lagochilus microtus= Andersen

1911. _Macroglossus lagochilus microtus_ Andersen, Ann. Mag. Nat.

Hist., Ser. 8, 7:642, June, type from Guadalca.n.a.l, additional specimens from Florida; 1912, Andersen, Catalogue of the Chiroptera ... British Museum, 1:767; 1931, Sanborn, Publ.

Field Mus. Nat. Hist., Zool. Ser., 18:22, February 12, from San Cristobal; 1953, Pohle, Z. Saugetierk., 17:130, October 27, from Bougainville; 1954, Laurie and Hill, List of land mammals of New Guinea, Celebes and adjacent islands, p. 44, June 30.

1888. _Macroglossus australis_ (part). Thomas, Proc. Zool. Soc.

London, p. 476, December 4, from Guadalca.n.a.l.

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; Guadalca.n.a.l 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. na.n.u.s_ Matschie, the subspecies of the Bismarck Archipelago and Admiralty Islands to the north of the Solomons. _M. l. na.n.u.s_ 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, dent.i.tion, 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; pos...o...b..tal region of skull expanded (about 8.3 wide), =Melonycteris aurantius=, p. 816

2'. Pelage dark, near Wood-Brown or Cinnamon; pos...o...b..tal region of skull constricted (about 7.5), =Melonycteris woodfordi=, p. 816

[Ill.u.s.tration: FIG. 11. Distribution of _Melonycteris aurantius_ [BC] and _M. woodfordi_ [LW]. For names of islands see Fig. 2.]

=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); pos...o...b..tal 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 pos...o...b..tal region is expanded (measuring about 8.3), whereas in _M. woodfordi_ the pos...o...b..tal 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_.

The number of upper incisors is highly variable in the six specimens of _M. aurantius_ that I have examined. In two specimens an extra tooth has erupted just anterior to I2 and there is a total of six upper incisors.

In two other specimens an extra tooth has erupted in front of I2 on one side but not the other. I could find no trace of an extra tooth in the remaining two specimens.

Practically nothing is known about the natural history of _M.

aurantius_, or, indeed, that of either of the other two species of this genus. One field collector (Temple, _in litt._) for the Bishop Museum reported that he obtained both _M. aurantius_ and _M. woodfordi_ in the same mist net in one night. The holotype, an adult female, was lactating when obtained in October.

=Melonycteris woodfordi= (Thomas)

1887. _Nesonycteris woodfordi_ Thomas, Ann. Mag. Nat. Hist., ser.

5, 14:147, February, type from Shortland Island; 1887, Thomas, Proc. Zool. Soc. London, p. 324, March 15; 1888, Thomas, Proc.

Zool. Soc. London, p. 476, December 4; 1898, Trouessart, Catalogus Mammalium ..., 1:90; 1899, Matschie, Die Megachiroptera ... naturkunde, p. 91; 1904, Trouessart, Catalogus Mammalium .., Suppl., p. 66; 1907, Miller, Bull. U. S. Nat. Mus., 57:74, June 29; 1912, Andersen, Catalogue of the Chiroptera ... British Museum, 1:792, from Alu, Shortland, Fauro, and Guadalca.n.a.l; 1931, Sanborn, Publ. Field Mus. Nat. Hist., Zool. Ser., 18:23, February 12, from Russell Island (Pavuvo); 1954, Laurie and Hill, List of land mammals of New Guinea, Celebes and adjacent islands, p. 45, June 30.

1953. _Melonycteris woodfordi_, Pohle, Z. Saugetierk., 17:130, October 27, from Bougainville Island; 1966, Phillips, Jour. Mamm., 47:23, March 12, from Choiseul.