Systematics of Megachiropteran Bats in the Solomon Islands Part 7

_Dobsonia_, a genus of large to medium-sized fruit bats, occurring from Celebes to the Solomon Islands, contains at least nine species. One species and its two subspecies are endemic to the Solomons.

_Dobsonia_ differs from all other genera of megachiropteran bats in the Solomons by combining absence of a small claw on the second digit and presence of external tail vertebrae.

The cranium of _Dobsonia_ resembles, in some ways, the cranium of _Rousettus_ as well as that of _Pteropus_. Even so, in _Dobsonia_ the rostrum is shorter and the cheek-teeth, especially in the upper jaw, are more crowded. The anterior part of the mandible is narrow and the lower incisors are diminutive and often concealed by the flesh of the gum.

=Dobsonia inermis=

In a review of the genus _Dobsonia_, Andersen (1909_c_:532) named and described _D. inermis_ and _D. nesea_ from the Solomons. Specimens of _Dobsonia inermis_ from San Cristobal and Ugi were said to differ from specimens of _D. nesea_ from Alu, Shortland, and Rubiana in having perpendicular as opposed to anteriorly slanted upper canines. Andersen (1909_c_:532) reported that the two species were of "... the same general size." Troughton (1936:348-349) studied specimens of _Dobsonia_ from Bougainville and Santa Ysabel and, because of individual variation in proclivity of the upper canines, concluded that _D. nesea_ was conspecific with _D. inermis_. He (p. 349) noted that the ears were shorter in _inermis_ than in _nesea_, but the size of teeth showed insular variation and a "... confusing amount of intergradation ...

[that obscures] ... diagnostic importance."

Specimens of _Dobsonia_ from Choiseul are smaller (externally and cranially) than those from Alu, Shortland, Rubiana, Bougainville, Fauro, Vella Lavella, Guadalca.n.a.l, Florida, Ugi, San Cristobal, and Rennell.

Specimens from Santa Ysabel (see Fig. 8) are intermediate in size between those from Choiseul and the other islands listed. Judging from available specimens, two subspecies of _Dobsonia inermis_ occur in the Solomons. Specimens from Choiseul (see A, Fig. 8), which are smaller than those from other islands, represent one subspecies (heretofore unrecognized), whereas specimens from other islands (except Santa Ysabel) represent a second subspecies. Specimens from Santa Ysabel are slightly larger than those on Choiseul and are regarded as intergrades between the two subspecies. Specimens from Rennell, Ugi, San Cristobal, Florida, Fauro, and Guadalca.n.a.l are slightly smaller than those from Bougainville, Vella Lavella, Shortland, and Rubiana, but the differences are not great enough to warrant recognition of two subspecies.

Therefore, the subspecific name _nesea_ is arranged as a synonym of _inermis_, which has priority, and the latter name is used for specimens of _Dobsonia inermis_ from the Solomon islands other than Choiseul and Santa Ysabel. Additional remarks on the distribution of this species are in the section on Zoogeography and Speciation.

Pohle (1953:130) suggested that _Dobsonia inermis_ (as well as _D.

crenulata_ and _D. praedatrix_) is conspecific with _D. viridis_, but Laurie and Hill (1954:41) did not adopt his suggestion. I have not seen adequate series of _crenulata_, _praedatrix_, and _viridis_ (none of which occurs in the Solomons) to judge systematic relationships of these kinds; therefore I follow Laurie and Hill.

=Dobsonia inermis inermis= Andersen

1909. _Dobsonia inermis_ Andersen, Ann. Mag. Nat. Hist., ser. 8, 4:532, December, type from San Cristobal; 1912, Andersen, Catalogue of the Chiroptera ... British Museum, 1:475.

1936. _Dobsonia inermis inermis_, Troughton, Rec. Australian Mus., 14:349, April 7, from Santa Ysabel; 1954, Laurie and Hill, List of land mammals of New Guinea, Celebes and adjacent islands, p. 41, June 30; 1956, Hill, The natural history of Rennell Island, British Solomon Islands, 1:74, November 28, from Rennell Island.

1878. _Cephalotes peroni_ (part), Dobson, Catalogue of the Chiroptera ... British Museum, p. 91; 1879, Trouessart, Rev.

Mag. Zool., 3:208; 1887, Thomas, Proc. Zool. Soc. London, p. 323, March 15, from Ugi and San Cristobal; 1888, Thomas, Proc. Zool. Soc. London, p. 476, December 4; 1897, Trouessart, Catalogus Mammalium ..., 1:87.

1899. _Dobsonia peroni_ (part), Trouessart, Catalogus Mammalium ..., 2:1278.

1909. _Dobsonia nesea_ Andersen, Ann. Mag. Nat. Hist., ser. 8, 4:532, December 1, type from Shortland Island; 1912, Andersen, Catalogue of the Chiroptera ... British Museum, 1:476, from Shortland and Rubiana; 1931, Sanborn, Publ. Field Mus. Nat.

Hist., Zool. Ser., 18:22, February 12, from San Cristobal.

1936. _Dobsonia inermis nesea_, Troughton, Rec. Australian Mus., 14:348, April 7, from Bougainville; 1953, Pohle, Z. Saugetierk., 17:130, October 27; 1954, Laurie and Hill, List of land mammals of New Guinea, Celebes and adjacent islands, p. 41, June 30, from New Georgia.

_Specimens examined_ (13 males and three females; three in alcohol, crania extracted and cleaned).--Fauro in April, 23728, 23740, 23751; Vella Lavella in November, 23134-36, 23141, 23145, 23147, 23149, 23151, 23153; Guadalca.n.a.l in May and June, 23865, 23914, 24008; Florida in October, 24416.

_Measurements._--See tables 2 and 3.

_Remarks._--Heretofore, _Dobsonia inermis inermis_ was unreported from Fauro, Vella Lavella, Guadalca.n.a.l, and Florida. Apparently the subspecies occurs on most islands of the archipelago (see Fig. 9).

In coloration and most cranial dimensions the specimens listed above agree with specimens of _D. i. inermis_ from Alu, Shortland, and Rubiana (Andersen, 1909_c_:532; 1912:475, 476), Bougainville (Troughton, 1936:348, 349), and Rennell (Hill, 1963:74). The forearm in the adult male holotype of "_nesea_," from Shortland, is 109.5 as opposed to 109.0 in an adult female topotype of _inermis_ from Ugi (Andersen, 1912:478) in the southeastern part of the archipelago (see Fig. 9). Forearms of specimens of _D. i. inermis_ from Vella Lavella are 107 to 112 (measurements from labels because forearms of these specimens were broken and therefore could not be remeasured). Forearms of specimens from Fauro, Florida, Guadalca.n.a.l, and Rennell are 103.6 to 110.0 (see Hill, 1956:74). Variation in length of forearm probably is not significant because no cline is evident (see Fig. 9 and Table 2).

In 1964, 11 specimens of _Dobsonia inermis_ were collected on Choiseul.

They are smaller, externally and cranially, than specimens of _D.

inermis_ from Sun Cristobal, Ugi, Rennell, Guadalca.n.a.l, Florida, Rubiana, Vella Lavella, Shortland, Alu, Bougainville, and Fauro, and may be named and described as follows:

=Dobsonia inermis minimus=, new subspecies

_Type._--Adult male skin and skull, in good condition (originally stored in 70 per cent alcohol for about one year), no. BBM-BSIP 23716, Bernice P. Bishop Museum; from Choiseul Island, British Solomon Islands Protectorate; obtained on 20 March 1964 by Philip Temple, original number 1524.

_Distribution._--Choiseul Island (type locality); intergrades from Santa Ysabel also a.s.signed to this subspecies.

_Diagnosis._--Size small for species; wing membranes, feet, and ears black; dorsal surface of interfemoral membrane spa.r.s.ely set with silvery hairs, other membranes naked; hair soft, medium length (10 on mantle, 5 on crown), black hairs and scattered white hairs on face and crown; fur of dorsal surface of mantle composed of whitish hairs having faint olive cast imparting general color of Buffy-Citrine; hair of venter short (about 5), soft, and fine; general coloration Buffy-Citrine; cranium delicate; rostrum narrow in dorsal aspect (nasals not expanded laterally); forehead (junction of nasals and frontals) p.r.o.nounced in lateral aspect; teeth resembling those of other subspecies of _D.

inermis_ but slightly smaller.

_Comparisons._--From adults of _Dobsonia inermis inermis_, which occurs on Rennell, San Cristobal, Ugi, Malaita, Florida, Guadalca.n.a.l, Rubiana, Vella Lavella, Shortland, Alu, Bougainville, and Fauro, _minimus_ differs in being smaller. Average length of mandible 31.2 and 33.4. For other measurements see Table 2.

From _Dobsonia praedatrix_, which occurs on New Britain, New Ireland, and Duke of York (northward of the Solomons), _minimus_ differs in being smaller in all dimensions; length of forearm averaging 100.5 as opposed to 116.0, and greatest length of skull 42.4 as opposed to 50.0.

[Ill.u.s.tration: FIG. 8. Greatest length of skull plotted against zygomatic breadth for two subspecies of _Dobsonia inermis_. Symbols represent _D. i. inermis_ ([BW]), _D. i. minimus_ ([TW]), and intergrades a.s.signed to _minimus_ ([BC]). Capital letters are used to relate groups of specimens to the island or islands from which they were collected; spatial distribution of specimens indicated in the scatter diagram thus is shown in the inset map. Specimens from Santa Ysabel and Bougainville are deposited in the Australian Museum. The type specimen of _D. i. inermis_ is labeled "E." For names of islands see Fig. 2.]

[Ill.u.s.tration: FIG. 9. Distribution of _Dobsonia inermis inermis_ ([BC]) and _D. inermis minimus_ ([RW]). For names of islands see Fig. 2.]

TABLE 2. Average and Extreme Measurements of Two Subspecies of _Dobsonia inermis_.

================+====================================+=================== _D. i. minimus_ _D. i. inermis_ +------------------+-----------------+------------------- Guadalca.n.a.l, MEASUREMENT Choiseul Santa Ysabel Fauro, Vella 4 [M], 2 [F] 1 [M], 2 [F] Lavella, Florida 9 [M], 2 [F]

----------------+------------------+-----------------+------------------- Length of head and body 174.5 (170 -180 ) 174.5 (160 -190 ) Tail vertebrae 28.5 (24 - 33 ) 23.0 (21.5-24.0) 30.4 ( 25 - 35 ) Hind foot 25.3 (25.1- 25.9) 23.5 (23.5-24.0) 29.3 ( 26.0- 31.6) Ear 21.5 (21.0- 22.9) 21.1 (21.0-21.5) 23.1 ( 19 - 25 ) Length of forearm 100.5 (98.1-104.0) 105.3 (104 -107 ) 108.4 (105 -112 ) 2nd metacarpal 43.6 (42.6- 45.2) 48.1 ( 45.9- 50.9) 3rd metacarpal 61.5 (59.8- 62.9) 67.6 ( 65.2- 68.5) 4th metacarpal 57.5 (56.5- 58.5) 62.5 ( 58.7- 65.5) 5th metacarpal 59.0 (57.0- 60.5) 64.4 ( 61.8- 66.0) Greatest length of skull 42.4 (42.1- 43.5) 44.0 (43.0-45.6) 45.9 ( 45.2- 47.4) Condylobasal length 40.4 (39.5- 41.3) 41.7 (41.1-42.6) 43.6 ( 43.1- 45.0) Zygomatic breadth 25.6 (24.9- 26.8) 26.5 (25.7-27.6) 27.9 ( 27.2- 28.5) Breadth of braincase 16.8 (16.5- 17.4) 18.0 (17.1-19.9) 17.9 ( 16.7- 19.0) Breadth across upper canines 8.4 ( 8.1- 8.7) 9.2 ( 9.2- 9.5) Breadth across first upper molars 12.1 (11.8- 12.6) 13.1 ( 12.6- 13.3) Length of maxillary tooth-row 15.6 (15.5- 15.8) 16.4 (16.0-17.2) 16.4 ( 15.9- 17.0) Length of mandibular tooth-row 17.1 (16.8- 17.6) 17.8 (17.3-18.4) 18.2 ( 17.8- 19.4) ----------------+------------------+-----------------+-------------------

_Measurements._--Comparative measurements of the subspecies _inermis_ and _minimus_ are given in Table 2. Some measurements of the type are as follows: Length of head and body, 147; tail vertebrae, 31; hind foot, 25; ear, 21; length of forearm, 99.5; 2nd metacarpal, 42.8; 3rd metacarpal, 62.7; 4th metacarpal, 58.5; 5th metacarpal, 59.1; greatest length of skull, 42.2; condylobasal length, 40.6; zygomatic breadth, 25.8; breadth of braincase, 16.8; length of maxillary tooth-row, 15.8; length of mandible, 31.2.

_Remarks._--_Dobsonia inermis minimus_ is the smallest subspecies of _Dobsonia inermis_. Specimens from Santa Ysabel, southeastward of Choiseul, are slightly larger than the type and paratypes of _minimus_.

As can be seen in the scatter diagram (Fig. 8), a male from Santa Ysabel is as large as one male and most females of _D. i. inermis_. The other three specimens from Santa Ysabel also are slightly larger than specimens of _minimus_ from Choiseul, but are much smaller than specimens of _D. i. inermis_, and, therefore, are referred to _D. i.

minimus_.

Although there is a cline in size of _Dobsonia inermis_ from Choiseul to Florida (generally southward; Fig. 9), no cline in size is apparent between Choiseul and Fauro (generally westward). Specimens of _D.

inermis_ from Fauro are average for the subspecies _inermis_; there is no evidence, in the small series available, of intergradation between _minimus_ on Choiseul and _inermis_ on Fauro.

_Specimens examined_ (eight males and three females, all originally in alcohol; seven crania, all adults, extracted and cleaned).--Choiseul in March, 23565, 23628, 23637, 23665-67, 23640, 23714, 23716 (holotype), 23717, 23720. Ellis LeG. Troughton kindly examined and measured nos.

AM-M. 3693[M], AM-M. 3694[M], AM-M. 3937[F], and AM-M. 3940[F], from Santa Ysabel in the Australian Museum.

Subfamily Macroglossinae

=Macroglossus= F. Cuvier

1824. _Macroglossus_ F. Cuvier, Des dents des mammiferes ...

zoologiques, p. 248.

1840. _Kiodotus_ Blyth, _in_ Cuvier's animal kingdom ..., p. 69.

1891. _Carponycteris_ Lydekker, _in_ Flower and Lydekker, mammals living and extinct, p. 654.

1902. _Odontonycteris_ Jentink, Notes Leyden Mus., 23:140, July 15.

_Macroglossus_, the widest-ranging genus of macroglossine bats, occurs from southeastern Asia to the southern islands of the Solomon Archipelago (see Ellerman and Morrison-Scott, 1966:101; Laurie and Hill, 1954:44). One species, known also from Celebes and New Guinea, occurs in the Solomons and is represented there by an endemic subspecies.