Table 3.—Selected measurements of adult Molossus molossus.
| Number of specimens averaged or catalogue number, and sex | Length of forearm | Greatest length of skull | Condylo- basal length | Zygo- matic breadth | Mastoid breadth | Breadth of brain- case | Postorbital constriction | Length of maxillary toothrow | Breadth across upper molars |
| Western Jalisco, México | |||||||||
| KU 109075, ♂ | 38.2 | 18.0 | 15.3 | 11.0 | 10.5 | 9.1 | 3.8 | 6.2 | 7.9 |
| KU 109076, ♂ | 37.3 | 17.8 | 15.3 | 11.0 | 10.5 | 9.2 | 3.6 | 6.3 | 8.1 |
| KU 120540, ♂ | 37.7 | 17.8 | 15.3 | 11.0 | 10.8 | 8.9 | 3.9 | 6.3 | 8.1 |
| Average 15 (♀) | 37.1 | 17.2 | 14.8 | 10.7 | 10.3 | 8.9 | 3.8 | 6.1 | 7.9 |
| Minimum | 36.0 | 16.5 | 14.2 | 10.4 | 10.1 | 8.5 | 3.7 | 6.0 | 7.7 |
| Maximum | 38.1 | 17.7 | 15.2 | 11.0 | 10.5 | 9.2 | 3.9 | 6.2 | 8.2 |
| Departamento de Chinandega, Nicaragua | |||||||||
| USNM 337552, ♂ | 39.0± | 18.2 | 15.5 | 11.0 | 10.7 | 9.0 | 3.7 | 6.0 | 8.0 |
| KU 114140, ♀ | 37.3 | 16.8 | 14.7 | 10.7 | 9.9 | 8.7 | 3.4 | "5.9 | 7.4 |
| 3 mi SW Managua, Nicaragua | |||||||||
| KU 71009, ♂ | 39.8 | 18.7 | 16.1 | 11.1 | 10.9 | 8.9 | 3.8 | 6.3 | 8.0 |
| KU 71011, ♂ | 39.4 | 18.5 | 16.5 | — | 11.0 | 9.2 | 3.7 | 6.7 | 8.0 |
| Average 5 (♀) | 38.9 | 17.5 | 15.4 | 10.7 | 10.3 | 9.0 | 3.6 | 6.1 | 7.8 |
| Minimum | 38.1 | 17.2 | 15.1 | 10.5 | 10.1 | 8.9 | 3.5 | 5.9 | 7.6 |
| Maximum | 39.7 | 18.0 | 15.9 | 10.9 | 10.6 | 9.1 | 3.7 | 6.3 | 8.0 |
| Santa Rosa, Boaco, Nicaragua | |||||||||
| Average 6 (♀) | 36.0 | 17.5 | 14.7 | 10.8 | 10.6 | 9.1 | 3.7 | 6.0 | 8.0 |
| Minimum | 35.5 | 17.3 | 14.4 | 10.6 | 10.4 | 9.0 | 3.6 | 5.7 | 7.8 |
| Maximum | 36.7 | 17.8 | 15.1 | 11.0 | 10.8 | 9.2 | 3.8 | 6.2 | 8.2 |
| Rivas, Nicaragua | |||||||||
| KU 106291, ♂ | 38.2 | 18.8 | 16.1 | 11.5 | 10.9 | 9.4 | 3.8 | 6.6 | 8.3 |
| KU 106290, ♀ | 39.6 | 17.4 | 15.0 | 11.0 | 10.5 | 9.1 | 3.6 | 6.0 | 7.7 |
| KU 106293, ♀ | 37.2 | 17.3 | 14.8 | 10.7 | 10.2 | 9.0 | 3.5 | 5.7 | 7.8 |
The localized and presumably highly inbred populations may have diverged morphologically, in some cases at least, to a degree that mensural differences can be demonstrated even between samples from the same general geographic area. Localized variation and relatively marked secondary sexual variation (unrecognized by some earlier workers), superimposed on geographic variation, have resulted in application of a relatively large number of names to these small Molossus. Felten (1957:13-14), for example, apparently used different specific names for males and females from El Salvador, and Gardner (1966) employed three different specific names for North American specimens. Only when material is available for a detailed study of variation throughout the Neotropics can the perplexing mosaic of characters in these small Molossus be assessed adequately.
We have seen no specimens from Nicaragua that are identifiable as Molossus bondae, another relatively small species that has been reported from Greytown (Miller, 1913a:89) and from elsewhere in Central America by other authors (Goodwin, 1942c:145; Handley, 1966b:772; Gardner et al., 1970:727). Our examination of the female holotype of M. bondae reveals that it is larger than M. molossus, corresponding in size to females recently reported from Costa Rica by Gardner et al. (loc. cit.), and that bondae has dark-based hairs. The two males reported by Goodwin (loc. cit.) from Honduras as bondae, would seem to be too small for that species, based on the measurements listed; also, these specimens allegedly have white-based hairs and probably represent M. molossus as here defined.
Molossus pretiosus pretiosus Miller, 1902
Specimens.—Boaco: Los Cocos, 14 km S Boaco, 220 m, 28; San Francisco, 19 km S, 2 km E Boaco, 200 m, 3. Carazo: 3 km N, 4 km W Diriamba, 600 m, 25. Managua: 6 mi WSW Managua, 3.
This relatively large mastiff bat has not been reported previously from Nicaragua. Specimens from several localities in Boaco were captured in mist nets over streams; most of those from northwest of Diriamba were shot in the early evening as they foraged high around large trees in a coffee finca, but several were netted over a water-filled concrete tank or found in the water in the tank as detailed in the account of Eptesicus furinalis. At Los Cocos, bats that we netted seemed to be emerging from a hollow located high in a tree over the stream.
Selected measurements of M. p. pretiosus from Nicaragua, which compare favorably with those of topotypes from Venezuela, are listed in Table 4 along with measurements of M. ater and M. sinaloae. The taxonomic relationships of M. pretiosus and M. ater are less than clear, and some authors (Handley, 1966b:773, for instance) have suggested that the two may be conspecific. Whatever their ultimate relationships may prove to be, two distinctive taxa seem to be present in Nicaragua; the larger is assignable to ater and the smaller to pretiosus, as currently understood. Furthermore, the presumed presence of two large Molossus with dark-based hairs elsewhere in Central America (Dilford C. Carter, personal communication) and in southeastern México (Goodwin, 1956:4; Goodwin and Greenhall, 1964:20) argues for specific recognition of pretiosus.
The species ater and pretiosus differ mainly in size (Table 4), some measurements clearly separating the two when sexual dimorphism is considered. Also, the average weights of 18 nonpregnant females and four males of pretiosus (all adults) collected on 20 February 1968 at Los Cocos, were 20.9 (14.6-23.8) and 27.0 (24.6-31.7) gms, respectively, significantly smaller than corresponding figures for 11 nonpregnant females and nine males of M. a. nigricans taken two weeks later on the Cosigüina Peninsula—29.1 (26.1-33.0) and 32.9 (29.3-35.1) gms. It is of note that we have not collected these two large species at the same localities in Nicaragua, and it is possible that one competitively excludes the other in local situations.
Table 4.—Selected measurements of adults of three species of Molossus from Nicaragua.