Natalidae Miller, 1899

Tejedor, Adrian, 2011, Systematics Of Funnel-Eared Bats (Chiroptera: Natalidae), Bulletin of the American Museum of Natural History 2011 (353), pp. 1-140 : 10-13

Family Natalidae Miller, 1899

TYPE GENUS: Natalus Gray, 1838 .

GEOGRAPHIC DISTRIBUTION: New World, from northern Mexico (Sonora and Baja California in the west and Tamaulipas in the east), through Central America (including several adjacent continental and oceanic islands), the West Indies (Greater and Lesser Antilles and the Bahamas), northern South America (northern Colombia, through Venezuela, and the Guianas, plus offshore Caribbean islands), eastern and central Brazil, to southern Brazil (São Paulo), eastern Bolivia and northeastern Paraguay; generally restricted to tropical environments (ranging from semiarid to wet) rich in caves, and below 2500 m (fig. 2; pls. 1–3).

DIAGNOSIS: Natalid organ present in males; funnel-shaped ears lacking a ridge or flap between lateral and ventral regions of pinna; ear ridges vestigial; lachrymal fossa present; long infraorbital canal, extending from P2 to M2; styliform process on rostral margin of ectotympanic; presence of cingular labial cusp on p4; lingual talonid crest of m3 straight; presence of protocone on P4; lack of upper molar ectocingulum; manubrium of sternum expanded laterally into platelike structure; long caudal vertebrae.

DESCRIPTION: Funnel-eared bats range in size from the very small Nyctiellus lepidus (2– 3 g, forearm length 26.6–31.0 mm), one of the world’s smallest bats, to the medium-sized Natalus primus (6.0– 12.6 g, forearm length 46.1–51.2 mm). Funnel-eared bats are characterized by slender bodies, long extremities and tail, and wide wing membranes. The tail is usually longer than the head and body combined, and is entirely enclosed in an extensive, triangular or wedge-shaped uropatagium. The wing membranes are thin and translucent. The plagiopatagium inserts either at the ankle or at the tibia. The calcar is long and in most species extends along most of the free edge of the uropatagium. The body pelage is long, from lax to woolly, and ranges widely in coloration from pale buff to rich chestnut brown. Usually, ventral hairs are monocolored and dorsal hairs are bicolored with darker tips and lighter bases, with the exception of N. lanatus , in which both ventral and dorsal hairs have darker bases and lighter tips. The muzzle is long, slender, and dorsoventrally flattened. Natalids have a relatively simple facial anatomy, lacking, with the exception of the genus Chilonatalus , the dermal folds and excrescences typical of other tropical bat families (pl. 4). The dense pelage along the lateral margins of the upper lips gives these bats the appearance of having thick mustaches. The mustache hairs are curved ventrally and may direct airflow toward the mouth and ear, as has been suggested for the bat family Mormoopidae ( Smith, 1972) . The nostrils are usually oval shaped, ventrolaterally oriented, and open at the end of a dorsally prominent longitudinal nasal ridge at the margin of the upper lip. The lower lip is thickened and bears paired central pads incised by numerous diagonal grooves with the appearance of primate dermatoglyphs.

Males have a unique organ called the natalid organ on the dorsal surface of the muzzle. This organ is generally visible externally as a swollen mass, which can be as large as half the skull length in the genus Chilonatalus (pl. 5). The natalid organ secretes a translucent greenish, viscous liquid that may function in communication.

The ears are medium to large in size, with the pinna square shaped and expanded laterally to various degrees, in most species having the appearance of a funnel with a pointed apex. The ventral surface of the ears is relatively smooth; the typical ear ridges of bats are extremely reduced in size and restricted to a narrow area near the lateral margin of the distal pinna (pl. 5). The hair follicles on the ventral surface of the ear are relatively conspicuous. There is no cartilaginous ridge or flap between the lateral and ventral regions of the ear pinna. The tragus is small and twisted with a lanceolate tip. The eyes are very small, partly surrounded by the bases of the ears, and are partially hidden by the profuse facial pelage.

The skull is long and delicate, with a long, narrow, and dorsoventrally flattened rostrum (pls. 6–14). The braincase varies from moderately inflated to globular and is usually sharply elevated above the rostrum. The premaxilla is expanded dorsally and caudally to various degrees. The palatal branches of the premaxilla are fused along the ventral midline, leaving two small foramina and a slight rostral emargination. The infraorbital canal extends from P2 to M2, and opens caudally in a depression termed the lachrymal fossa ( Morgan and Czaplewski, 2003). The ectotympanic is expanded rostrally into a styliform process. The condyloid and coronoid processes of the mandible are at nearly the same level above the alveolar plane. The angular process is long and has a dorsally or anterodorsally curved tip (pl. 15). The dental formula is 2/3, 1/1, 3/3, 3/3 5 38. There is a small gap between i3 and the lower canine. There is an accessory cusp on the labial cingulum of p4 of various degrees of development. The lingual talonid crest of m3 is straight. A protocone is present in P4 and the mesostyle of the upper molar series is elongated rostrocaudally forming an accessory crest termed a mesostylar crest ( Morgan and Czaplewski, 2003; pl. 16).

The humerus is characterized by a distal articular surface displaced laterally relative to the longitudinal axis of the humerus, a broad, triangular-shaped epitrochlea, and tuberosities of similar size (pl. 17). The axial skeleton has various degrees of fusion between its constituting bones. The vertebrae C7 to T1 up to C7 to T6 are fused among them and with the ribs. The vertebrae from last thoracic to antepenultimate or penultimate lumbar are fused into a continuous, laterally compressed column with no evidence of sutures between elements. The sternum is expanded laterally into a platelike structure. The ribs are greatly expanded craniocaudally or fused entirely among them and with the sternum into a rigid thoracic bell-shaped structure (pl. 18). The tail vertebrae are greatly elongated.

KEY TO BATS OF THE FAMILY NATALIDAE

1 Free margin of uropatagium naked, lacking a fringe of hairs (fig. 3A); tibia less than half the length of the forearm; calcar occupying less than half the length of the free margin of uropatagium........... Nyctiellus lepidus

— Free margin of uropatagium with a fringe of hairs (fig. 3B); tibia more than half the length of the forearm; calcar occupying more than half the length of the free margin of uropatagium........................... 2

2 Muzzle showing a distinctive tubercle above nostrils and a small flap of skin below lower lip (fig. 4A)......................... 3

— Muzzle smooth, lacking a tubercle above nostrils and a flap of skin below lower lip (fig 4B)......................... 5

3 Tibia short, lateral margin of ear concave (fig. 5B); in males, penis long (3.6–6.5 mm) and natalid organ small and hemispheric (fig. 5B)........... Chilonatalus micropus

— Tibia long, lateral margin of ear straight (fig. 5A); in males, penis short (1–2.5 mm) and natalid organ large and elliptical (fig. 5A)......................... 4

4 Greatest skull length 13.9–14.7 mm ......................... Chilonatalus macer — Greatest skull length 15.0–16.0 mm...................... Chilonatalus tumidifrons

5 Ungual hair tuft present (fig. 6A)............................... Natalus lanatus

— Ungual hair tuft absent (fig. 6B)........ 6

6 Lateral margin of ear pinna straight. Natalus primus

— Lateral margin of ear pinna concave..... 7

7 Medial margin of ear pinna straight (fig. 5B) .................................. 8

— Medial margin of ear pinna slightly to deeply concave (fig. 5C)................... 9

8 Maxilla concave dorsal to molars (fig. 7A);.................... Natalus jamaicensis

— Maxilla convex dorsal to molars (fig. 7B);........................... Natalus major

9 Caudal end of palate rostral to sphenorbital fissure (fig. 8A)....... Natalus tumidirostris

— Caudal end of palate caudal to sphenorbital fissure (fig. 8B).................... 10

10 Rostrum short and wide, breadth across molars 80 % –85 % of toothrow length..................... Natalus espiritosantensis

— Rostrum long and narrow, breadth across molars 72 % –81 % of toothrow length.... 11

11 I1 rostral to I 2 in ventral view (fig. 9A)....................... Natalus mexicanus

— I1 at level with I 2 in ventral view (fig. 9B)...................... Natalus stramineus