Part 7

A broken skull (USNM 339917) of a female of this species from Hda. Mecatepe [2 km N, 11.5 km E Nandaime, ca. 40 m], Granada, represents the only known specimen of the genus Eumops from Nicaragua. This bat was obtained by M. K. Clark on 25 August 1964, but the conditions under which it was captured are not known. Available cranial measurements are: zygomatic breadth, 12.6 mm; breadth of braincase, 10.7 mm; postorbital breadth, 4.3 mm; rostral breadth, 7.4 mm; length of maxillary toothrow, 9.1 mm; length of mandibular c-m3, 10.0 mm.

Molossus ater nigricans Miller, 1902

Specimens.--Chinandega: Potosí, 5 m, 21; 4.5 km N Cosigüina, 15 m, 2; El Paraíso, 1 km N Cosigüina, 20 m, 17; Hda. Bellavista, 720 m, Volcán Casita, 4; Hda. San Isidro, 10 km S Chinandega, 20 m, 2; San Antonio, 35 m, 2. Nueva Segovia: Corozo, 15 km NNE Jalapa, 660 m, 1; 3.5 km S, 2 km W Jalapa, 660 m, 4.

Only one specimen of this large molossid (from Volcán de Chinandega--J. A. Allen, 1908:670) has been reported from Nicaragua. All of our specimens are from the northern or northwestern part of the country. Many were shot in early evening as they followed a straight, direct flight pattern (presumably from day-roosts toward foraging or watering areas); the series from Potosí was netted over a small stream as described in the account of Noctilio leporinus. We confidently refer our material to the species currently known as ater, although assignment to the subspecies nigricans is tentative.

Of 21 females autopsied in the first week of March on the Cosigüina Peninsula, seven were pregnant, each with a single embryo (7-22 mm in crown-rump length, average 16.7). Ten males taken at the same time had an average testicular length of 5.7 (2-7) mm, whereas the testes of a male obtained on 9 March at San Antonio measured 8 mm. None of five females obtained in late July in Nueva Segovia evidenced reproductive activity, nor did two of three females taken in July and one taken in August from Chinandega; the fourth Chinandegan female, taken on 17 July, carried an embryo that was 36 mm in length. Two males from southern Chinandega (mid-July) had testes 7 and 4 mm long.

Representative measurements of 10 specimens of each sex from Nicaragua are given in Table 4.

Molossus molossus aztecus Saussure, 1860

Specimens.--Chinandega: Potosí, 5 m, 1; Hda. San Isidro, 10 km S Chinandega, 20 m, 1 (USNM). Boaco: Santa Rosa, 17 km N, 15 km E Boaco, 300 m, 7. Managua: 3 mi SW Managua, 8. Rivas: Rivas, 60 m, 4.

This small free-tailed species has been reported from Nicaragua by Felten (1957:14), who listed two females from Corinto. Our records indicate that it is widely distributed, but of localized occurrence. Specimens from Potosí and Santa Rosa were captured in mist nets over streams (as described in the accounts of Noctilio leporinus and Myotis elegans, respectively). The specimen from Hda. San Isidro was shot in flight, whereas those from Rivas were captured in a daytime retreat in a deep crevice in a concrete school building. We have no precise knowledge of the conditions under which bats from 3 mi SW Managua were obtained but suspect they were taken from a building.

Females in our series were reproductively active at all times for which we have information--early March through mid-July--as follows: a female from Potosí (6 March) carried an embryo that measured 5 mm (crown-rump length) as did one from Santa Rosa (21 March, 17 mm in length); two of three females taken 3 mi SW Managua on 28 March were pregnant (embryos 13 and 15 mm), whereas each of two collected there on 3 May were gravid (embryos 27 and 30 mm); one female from Rivas (25 June) carried an embryo (30 mm) and another was lactating and accompanied by a small (forearm, 19.7 mm) hairless juvenile; and, finally, one of six females netted at Santa Rosa on 13 July was pregnant (embryo 23 mm), but the others evinced no reproductive activity. An adult male, taken at Rivas with the females mentioned above, had testes that were 6 mm in length.

Bats of the genus Molossus are in need of thorough systematic study. We think most, if not all, mainland populations of small Molossus with pale-based hairs pertain to the species Molossus molossus, originally described from the Lesser Antilles. Although there is some variation in size and overall color among our Nicaraguan samples, all seem to represent that species. Because specimens from Nicaragua closely resemble examples of M. m. aztecus from Jalisco, México (Table 3), in external and cranial proportions, we tentatively refer them to aztecus.

In our field experience in both Middle and South America, colonies of M. molossus tend to be extremely localized, with individual populations or demes frequently separated by many miles of territory in which the species seemingly does not regularly occur.

TABLE 3.--Selected measurements of adult Molossus molossus.

Table Legend:

Col. A: Number of specimens averaged or catalogue number, and sex Col. B: Length of forearm Col. C: Greatest length of skull Col. D: Condylobasal length Col. E: Zygomatic breadth Col. F: Mastoid breadth Col. G: Breadth of braincase Col. H: Postorbital constriction Col. I: Length of maxillary toothrow Col. J: Breadth across upper molars

====================================================================== A B C D E F G H I J ---------------------------------------------------------------------- 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 ([Female]) 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, [Female] 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 ([Female]) 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 ([Female]) 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, [Female] 39.6 17.4 15.0 11.0 10.5 9.1 3.6 6.0 7.7 KU 106293, [Female] 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