_Specimens._--_Chinandega_: Potosi, 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 Potosi 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 Potosi (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, Mexico
(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, Mexico
KU 109075, [Male] 38.2 18.0 15.3 11.0 10.5 9.1 3.8 6.2 7.9
KU 109076, [Male] 37.3 17.8 15.3 11.0 10.5 9.2 3.6 6.3 8.1
KU 120540, [Male] 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