VESPERTILIONIDAE Brown Bats FAUNA PARAGUAY

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See below for a key to the Paraguayan species.

VESPERTILIONIDAE: EVENING BATS
General characteristics: Thirteen Paraguayan species of small to large insectivorous bat. The face is simple with small eyes and a short snout. All species have a very long tail which reaches to the tip of, but is completely enclosed by, the uropatagium. Both the tail and uropatagium are tucked below the body when roosting. The tragus is well-developed but the anti-tragus is almost absent. Flight is rapid and agile, the tail membrane often being used to scoop up aerial prey as an aid to capture. Genera are best separated by ear size and shape.
Cranial characteristics: Species of this family are characterized by the emarginated palate, a broad space at the mid-line of the skull separating the incisors. Postorbital processes are absent. Premaxillae are separated.
Click here to see the Vespertilionidae Comparative Skull Gallery
Skeletal characteristics: Trochiter larger than the trochin and extends beyond the head of the humerus, broadly articulating with the scapula. Digit III with three phalanges, the third of which is ossified at the base. Digit II with a well-developed metacarpal and one small ossified phalanx. Seventh cervical vertebrae and all lumbar vertebrae are free.

Eptesicus Rafinesque, 1820: Big Brown Bats
General characteristics: Three Paraguayan species with medium-sized triangular ears and rounded tragus. Pelage basally darker.
Dental characteristics: Dental formula I2/3 C1/1 P1/2 M3/3 = 32. Well-developed upper incisors with inner incisors larger than outers. Lower incisors trifid and subequal. Crown of third lower incisor wider than crowns of either of the first two. Canines with distinct cingulum but no secondary cuspules. Large premolar located immediately behind the canine leaving no space (cf Myotis).
Eptesicus brasiliensis - Brazilian Brown Bat
Eptesicus diminutus - Diminutive Brown Bat
Eptesicus furinalis - Common Brown Bat

Histiotus P.Gervais, 1856: Leaf-eared Bats
General characteristics: Two Paraguayan species of medium-sized Vespertilionid with very long ears. The genus is known from the Pleistocene of Brazil and late Pliocene or early Pleistocene of North America.
Taxonomy: Hoofer & Van den Bussche (2003) concluded that Histiotus is closer to the New World Eptesicus than members of that genus are to their Old World counterparts and treated Histiotus as a subgenus to avoid paraphyly.
Histiotus macrotus - Greater Leaf-eared Bat
Histiotus velatus - Tropical Big-eared Bat

Lasiurus Gray, 1831: Hairy-tailed Bats
General characteristics: Three medium to large Paraguayan species all immediately identifiable by the varying amounts of furring on the uropatagium. They have short, rounded ears. Fossil material is known from the Pleistocene of South America and Early Pliocene of North America.
Cranial characteristics: Premaxillae and upper incisors separated by a large palatal emargination that extends approximately a third of the distance across the canines.
Dental characteristics: Dental formula I1/3 C1/1 P1-2/2 M3/3 = 30-32.
Lasiurus blossevillii - Southern Red Bat
Lasiurus cinereus - Hoary Bat
Lasiurus ega - Southern Yellow Bat

Myotis Kaup, 1829: Little Brown Bats
General characteristics: - Five small to medium-sized Paraguayan species. The most widely distributed genus of mammals other than man. All species have medium-sized, triangular ears and pointed tragus.
Dental characteristics: Dental formula I2/3 C1/1 P3/3 M3/3 = 38. Large space between the first canine and the premolar (cf Eptesicus). Great disparity in size between the first two and third premolar. Upper middle premolar often displaced inwards so the P1 and P3 make contact.
Myotis albescens - Silver-tipped Myotis
Myotis nigricans - Black Myotis
Myotis riparius - Riverside Myotis
Myotis ruber - Red Myotis
Myotis simus - Velvety Myotis

Key to Adults of Paraguayan Evening Bats

1a Uropatagium unfurred or with sparse border of hairs along body margin..........................................................2
1b Uropatagium densely-furred for at least basal half. Ears short and rounded....................................................12

2a Ears proportionately very long (>20mm) extending beyond the tip of the nose when pushed forward............3
2b Ears of medium length (<20mm) do not extend beyond snout when laid forward...........................................4

3a Ears <30mm long, pointed and connected by a conspicuous membrane. Pelage dark................Histiotus velatus
3b Ears very long >30mm, rounded and connected by inconspicuous membrane that is sometimes difficult to see. Pelage pale..............................................................................................................................Histiotus macrotus

4a Uropatagium naked. Upper incisors larger than outer incisors. No space between canine and premolars. Tragus rounded......................................................................................................................................................5
4b Uropatagium may have fringe of hairs next to body. Upper incisors uniform in size. Upper premolar 1 and 2 much reduced giving impression of a space between the canine and premolar 3. Tragus pointed.........................7

5a Forearm <36mm.....................................................................................................................Eptesicus diminutus
5b Forearm >36mm..............................................................................................................................................6

6a Forearm >41mm (typically in range 43-46mm).....................................................................Eptesicus brasiliensis
6b Forearm in range 36-42mm.......................................................................................................Eptesicus furinalis

7a Dorsal pelage reddish or orange-yellow............................................................................................................8
7b Dorsal pelage blackish or brown.....................................................................................................................10
NB: Myotis levis has been reported for Paraguay but the record was considered dubious by López-González (2005). This species has yellowish-brown pelage with darker bases, giving a frosted appearance. Pelage is long (4.5-5.5mm) and silky. The plagiopatagium insertion is in line with the toes. There is a fringe of hair along the border of the uropatagium which it shares only with M.albescens. Uropatagium has a white or pale border. Forearm 35-39mm.

8a Pelage long (>3mm) and reddish to reddish-brown. Plagiopatagium insertion in line with the toes................9
8b Pelage short (<3mm) and velvety, orange-yellow in colour. Pelage does not extend onto uropatagium. Forearm >37mm. Plagiopatagium insertion in line with the heel..........................................................Myotis simus

9a Pelage silky. Colour cinnamon-red. Hair on dorsal side of uropatagium extends to the knee or beyond. Forearm >38mm....................................................................................................................................Myotis ruber
9b Pelage woolly. Colour reddish-brown. No fringe of hair on dorsal side of uropatagium. Forearm <37mm...............................................................................................................................................Myotis riparius

10a Dorsal pelage bicoloured giving strongly frosted appearance. Ventral pelage whitish or noticeably pale. Fringe of hair along border of uropatagium. Wing membranes pale. Forearm in range 32-37mm.....Myotis albescens
10b Dorsal pelage slightly bicoloured or not bicoloured, with frosting effect slight or absent. No fringe of hair along border of uropatagium. Forearm in range 29-36mm....................................................................................11

11a Pelage silky and long (>5mm). Dorsal colour brown, dark brown (Chaco) or black. Forearm in range 29-35mm (mean 32.5mm)......................................................................................................................Myotis nigricans
11b Pelage woolly and medium-length (3-5mm). Dorsal colour brown, never black. Forearm in range 32-36 mm (mean 34.5mm)..................................................................................................................................Myotis riparius

12a Uropatagium furred only to basal half. Pelage yellowish with darker bases. Wing membranes pale. Forearm <44mm..................................................................................................................................................Lasiurus ega
12b Uropatagium fully furred on dorsal side.........................................................................................................13

13a Forearm >45mm. Pelage blackish with frosted appearance and yellow "balaclava". Wing membranes black with white spot on elbow and reddish or whitish colours bordering wing bones.............................Lasiurus cinereus
13b Forearm <42mm. Pelage reddish with frosted appearance....................................................Lasiurus blossevilli

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.
Hoofer SR & Van den Bussche RA 2003 - Molecular Phylogenetics of the Chiropteran Family Vespertilionidae - Acta Chiropterologica 5(Supp):p1.63.
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.
Redford K 1992 - Mammals of the Neotropics Vol 2: The Southern Cone Chile, Argentina, Uruguay and Paraguay - University of Chicago Press.