KU 96251, [Male] 32.3 18.4 8.8 7.6 7.0
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[a] Specimens labeled with reference to Dario, Diriamba, and
Managua.
Four of the five specimens taken northwest of Diriamba were shot from
a daytime retreat in a culvert; the fifth was caught by hand as it
attempted to fly out of a hollow, fallen tree. Two adult females
captured on 31 March were pregnant, each carrying a single embryo (13
and 14 mm in crown-rump length), whereas two obtained on 14 August
showed no sign of reproductive activity. An adult male, also taken
on 14 August, had testes 2 mm in length. Of three additional adult
females, one captured on 3 June was pregnant (embryo 21 mm in
crown-rump length), whereas two obtained on 14 April evinced no gross
reproductive activity.
The subspecies _mexicana_ has not been reported previously from
Nicaragua, although Gardner _et al._ (1970:715) recently extended its
known distribution southward from Honduras (Goodwin, 1942c:124) and El
Salvador (Felten, 1956:180) to west-central Costa Rica. In Nicaragua,
as apparently in Costa Rica, _mexicana_ occupies the Pacific versant,
the Caribbean lowlands being inhabited by the smaller race,
_Micronycteris megalotis microtis_ Miller, 1898 (type locality,
Greytown, Nicaragua--reported also from "Rio Coco," Nicaragua, by J. A.
Allen, 1910:110). Nicaraguan examples of _M. m. mexicana_ are, on the
average, considerably larger in cranial dimensions and length of
forearm than are specimens of _M. m. microtis_ (see Table 1). The
series of _microtis_ from "Rio Coco," probably from the headwaters of
that stream in the vicinity of San Juan de Rio Coco and thus near the
divide between Caribbean and Pacific drainages, is intermediate in size
between the two subspecies and suggests intergradation between them. As
noted also by Gardner _et al._ (1970:715), we find no differences in
length of ear between _microtis_ and _mexicana_ (contrary to Miller's
claim, in the original description, that _microtis_ had noticeably
smaller ears), nor do we note any consistent differences in color
between the two races on the basis of the specimens at hand.
Our specimens from Isla del Maiz Grande inexplicably agree rather
closely in size (average but slightly smaller) with specimens of _M. m.
mexicana_ from western Nicaragua and elsewhere within the range of the
subspecies, and are tentatively, therefore, referred to _mexicana_.
Four specimens earlier reported (G. M. Allen, 1929:130) from the same
island also are relatively large (forearm 35 mm). Further commentary on
this insular population must await a time when additional material is
available from Central America.