MOLOSSIDAE Free-tailed Bats FAUNA PARAGUAY

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See below for a key to the Paraguayan species.

MOLOSSIDAE: FREE-TAILED BATS
General characteristics: Seventeen species of small to large bats characterized by the long, thick, bare tail extending beyond the uropatagium for at least half its length. The body is flattish and rectangular (an adaptation for roosting in crevices) with short fur. Wing and tail membranes are leathery, the latter supported by short, broad, hairy feet and well-developed calcaneous. The head is dog-like, with long pointed snout, wide mouth and small to medium blackish eyes. Many species are sexually dimorphic, males being generally larger and having more conspicuous throat glands than females. The complex ears have broad, inward-facing edges, a well-developed antitragus and a broad lower edge that extends above the eyebrow - their structure is useful in identification. The tragus is reduced. Flight is strong, rapid and erratic on long, narrow wings, often at higher altitude than other bats. The diet is insectivorous. Many species utter clearly audible chatters. When threatened, bats of this family open the mouth, withdraw the lips and expose the sharp teeth. Fossils are known from the Oligocene, Miocene and Pleistocene of South America.
Cranial characteristics: Robust with no orbital processes. Click here to see the Molossidae Comparative Skull Gallery
Dental characteristics: Molars W-shaped.
Taxonomy: The family is split into two subfamilies by Gardner (2007). All Paraguayan species belong to the subfamily Molossinae P.Gervais, 1856. The Paraguayan species can be classified into seven genera. Identification to species level requires accurate measurements of specimens.

Cynomops O.Thomas, 1920: Dog-faced Bats
General characteristics: Two Paraguayan species. Ears bluntly rounded and lacking a flexible fold where they meet the head. Antitragus is as high as it is wide and tragus less than a third of the size of the antitragus.
Skeletal characteristics: Second phalanx shorter than the first in digits III and IV. Basisphenoid pits absent or weakly developed.
Dental characteristics: Dental formula I1/2 C1/1 P2/2 M3/3 = 30. Upper molars lack a third comissure.
Taxonomy: This genus has been traditionally included in an expanded Molossops, but is clearly distinguishable given the characteristics noted above and the separation has been confirmed at the molecular level.
Cynomops abrasus - Cinnamon Dog-faced Bat
Cynomops planirostris - White-throated Dog-faced Bat

Eumops Miller, 1906: Bonneted Bats
General characteristics: Six Paraguayan species varying in size from small to large Molossids. Ears large, rounded and joined medially on the forehead with a greatly developed keel. Tragus reduced and pointed or square-tipped. Antitragus large and oval. Smooth upper lip. Throat sacs present in some species secrete a strong odour when handled. Fossils date from the middle Miocene of Colombia.
Cranial characteristics: Skull slender and smooth with cylindrical interorbital region. Palate slightly arched. Basisphenoid pits well-developed.
Dental characteristics: Dental formula I1/2 C1/1 P1-2/2 M3/3 = 28-30. Upper incisors long and curved. Molars with W-shaped ectoloph. M3 with variably developed third commissure. First premolar occasionally absent.
Eumops auripendulus - Black Bonneted Bat
Eumops bonariensis - Southern Bonneted Bat
Eumops dabbenei - Dabbene´s Bonneted Bat
Eumops glaucinus - Wagner's Bonneted Bat
Eumops patagonicus - Patagonian Bonneted Bat
Eumops perotis - Greater Bonneted Bat

Molossops W.Peters, 1866: Dwarf Dog-faced Bats
General characteristics: A single Paraguayan species. Characterised by the large tragus, at least 50% of the size of the antitragus. Antitragus is short and wider than it is high with a posterior notch. Ears elongated and pointed with a flexible fold where they join the head. Second phalanx of digits III and IV is equal to or longer than the first phalanx. Broad face. Smooth lips. Conspicuous lines of fur diverge from angle of wing-bend along forearm and digit IV.
Cranial characteristics: No anterior palatal emargination. Well-developed basisphenoid pits usually oval in outline
Dental characteristics: Dental formula I1/1 C1/1 P2/2 M3/3 = 28.
Molossops temminckii - Dwarf Dog-faced Bat
A second species, the Rufous Dog-faced Bat M.neglectus, Williams & Genoways 1980 was mapped for Paraguay by Gardner (2007) although there are apparently no specimens from the country. Externally very similar to M.temminckii and possibly overlooked, they are best distinguished by forearm measurements, being <33mm in M.temminckii and >36mm in M.neglectus.

Molossus E.Geoffroy St-Hilaire, 1805: Velvety Mastiffs
General characteristics: Three Paraguayan species. Smoothly angled forehead. Smooth lips. Base of short, rounded ears meet on the forehead. Small tragus and well-developed antitragus constricted at the base. Well defined keel on ears. Snout lacks a well-defined medial ridge behind the nostrils. Some species with more than one colour phase.
Cranial characteristics: Sagittal crest well-developed. Palate arched, though not as much as in Promops. Basisphenoid pits distinct.
Dental characteristics: Dental formula I1/1 C1/1 P1/2 M3/3 = 26. Superior incisors triangular, short and relatively broad. They are angled downwards and barely project forward from the canines. Upper molars with little or no trace of a hypocone.
Molossus rufus - Black Mastiff
Molossus currentium - Corrientes Mastiff
Molossus molossus - Pallas's Mastiff

Nyctinomops Miller, 1902: Wrinkled-lipped Free-tails
General characteristics: Two Paraguayan species. Wrinkled upper lip. Very large ears unified medially. Antitragus higher than it is wide and tragus small and rectangular.
Cranial characteristics: Narrow rostrum. Anterior palatal emargination narrow.
Dental characteristics: Dental formula I1/2 C1/1 P2/2 M3/3 = 30. Superior incisors parallel. Third commissure of M3 well-developed and as long as the second.
Skeletal characteristics: Second phalanx of digit IV shorter than first.
Nyctinomops laticaudatus - Geoffroy´s Free-tailed Bat
Nyctinomops macrotis - Big Free-tailed Bat
Gardner (2007) states that Peale´s Free-tailed Bat Nyctinomops aurispinosus extends southwards into Paraguay but there are apparently no records of the species in the country (López-Gonzalez 2005). This species is intermediate between the documented species in size but is closest to N.laticaudatus. N.laticaudatus has a forearm typically in the range 40-46mm and the greatest skull length is <19mm. N.aurispinosus has a forearm length >47mm but <55mm and the greatest skull length is in the range 19-22mm

Promops Miller, 1902: Domed-palate Mastiffs
General characteristics: Two species both present in Paraguay. Steep snout and no forehead giving rectangular-headed aspect. Well-developed calcaneous. Short, rounded ears with a narrow keel meet on forehead. Antitragus pendant and constricted at base, tragus minute. Small muzzle pad lacks processes. Smooth lips. Medial ridge extending from behind the nose to the ears. Throat sac present.
Cranial characteristics: Short, broad skull with strongly domed palate. Well-defined basisphenoid pits.
Dental characteristics: Dental formula I1/2 C1/1 P2/2 M3/3 = 30. Upper incisors curved and slender, less than half the height of the canines. Lower incisors weakly bifid, outer incisors being crowded behind the inner incisors. Anterior upper premolars reduced to spicules and often missing. Third commissure of M3 is reduced or absent.
Promops centralis - Crested Mastiff
Promops nasutus - Brown Mastiff

Tadarida Rafinesque, 1814: Guano Free-tails
General characteristics: One Paraguayan species. Inner margin of ears arise from the same point. Antitragus wider than it is high. Tragus with square outline and well-developed. Wrinkled upper lip. Small glandular throat sac in male. Rostrum fairly broad. Second phalanx of 4^th digit long.
Cranial characteristics: Basisphenoid pits shallow or moderate in depth. Palate anteriorly emarginate.
Dental characteristics: Dental formula I1/2-3 C1/1 P2/2 M3/3 = 30-32. Superior incisors not parallel. Third commissure of M3 usually equal to or longer than second.
Tadarida brasiliensis - Brazilian Free-tailed Bat

Key to Adults of Paraguayan Free-tailed Bats

1a Lips with deep folds or grooves. Antitragus broader at base than it is high.......................................................2
1b Lips smooth, lacking folds or grooves...............................................................................................................4

2a Ears joined at the base. Rostrum long. Two pairs of lower incisors. Second phalange of fourth digit <5mm..3
2b Ears separated by small gap. Rostrum short. Three pairs of lower incisors. Second phalange of fourth digit >7mm. .........................................................................................................................................Tadarida brasiliensis

3a Forearm <50mm.............................................................................................................Nyctinomops laticaudatus
3b Forearm >55mm..................................................................................................................Nyctinomops macrotis

4a Antitragus constricted at base...........................................................................................................................5
4b Antitragus not constricted at base....................................................................................................................9

5a Calcaneous extends to tail. Two pairs of lower incisors....................................................................................6
5b Calcaneous does not extend to tail. One pair of lower incisors........................................................................7

6a Forearm >50mm........................................................................................................................Promops centralis
6b Forearm <50mm.........................................................................................................................Promops nasutus

7a Forearm >45mm...............................................................................................................................................8
7b Forearm <45mm............................................................................................................................Molossus rufus

8a Forearm <41mm.......................................................................................................................Molossus molossus
8b Forearm in range 41-45mm....................................................................................................Molossus currentium

9a Ears small, pointed or rounded. Ears separated by at least 1.5mm on forehead. One upper premolar...........10
9b Ears large, broad and expanded laterally. Ears joined across forehead. Two upper premolars........................12

10a Forearm >41mm.....................................................................................................................Cymonops abrasus
10b Forearm <41mm............................................................................................................................................11

11a Extensive white area on throat, frequently extending to venter. Antitragus large and square........................................................................................................................................Cymonops planirostris
11b Throat pale but not white, and pale area never extends to venter. Antitragus small and narrow.......................................................................................................................................Molossops temminckii

12a Forearm <50mm...........................................................................................................................................13
12b Forearm >50mm...........................................................................................................................................14

13a Forearm in range 45-50mm. Inner ridge of ear terminates beyond posterior border of antitragus.....................................................................................................................................Eumops bonariensis
13b Forearm <45mm. Inner ridge of ear does not extend beyond posterior border of antitragus.....................................................................................................................................Eumops patagonicus

14a Forearm >70mm...........................................................................................................................................15
14b Forearm <70mm...........................................................................................................................................16

15a Ears >35mm long, extending beyond the tip of the snout when laid forward. Tragus large, broad and square.................................................................................................................................................Eumops perotis
15b Ears <35mm long, do not extend beyond the tip of the snout when laid forward. Tragus small and slender with rounded or square tip..............................................................................................................Eumops dabbenei

16a Tragus square and broad. Pelage pale.......................................................................................Eumops glaucinus
16b Tragus small and triangular. Pelage dark............................................................................Eumops auripendulus

REFERENCES
Barquez RM, Giannini MP & Mares MA 1993 - Guía de los Murciélagos de Argentina - University of Oklahoma
Diaz MM & Barquez RM 2002 - Los Mamíferos de Jujuy, Argentina - LOLA-
Emmons LH & Feer F 1999 - Mamíferos de los Bosques Húmedos de América Tropical - FAN Bolivia.
Gardner AL 2007 - Mammals of South America Volume 1: Marsupials, Xenarthrans, Shrews and Bats - University of Chicago Press.
López-Gonzalez C 1998 - Systematics and Zoogeography of the Bats of Paraguay - PhD Thesis Texas Tech University
López-Gonzalez C 2005 - Murciélagos del Paraguay - Biosfera Numero 9.
Novak R ed 1991 - Walker´s Mammals of the World 5th Ed Volume 1 - Johns Hopkins
Redford K 1992 - Mammals of the Neotropics Vol 2: The Southern Cone Chile, Argentina, Uruguay and Paraguay - University of Chicago Press.