A Synopsis of the American Bats of the Genus Pipistrellus by Eugene Raymond Hall

Four nominal species of the genus _Pipistrellus_ are currently recognized in North America. They are _Pipistrellus subflavus_ (F. Cuvier) of eastern North America, _Pipistrellus hesperus_ (H. Allen) of western North America, _Pipistrellus veracrucis_ (Ward) from Veracruz, Mexico, and _Pipistrellus cinnamomeus_ Miller from Tabasco, Mexico.

In the past three years, specimens have been obtained in Veracruz (by Dalquest) of each of the southern species. One of these, _P. cinnamomeus_, previously was known from a single specimen; the other, _P. veracrucis_, was known only from six specimens which now are lost or misplaced. The results of our study of these recently acquired Mexican specimens constitute our principal contribution in this paper; we have done little more with the material from the United States and Canada than to codify the findings of other mammalogists with respect to the systematic status and geographic distribution.

Study of the available specimens reveals that there are only two species, _Pipistrellus hesperus_ and _Pipistrellus subflavus_; _Pipistrellus veracrucis_ proves to be only a subspecies (geographic race) of _P. subflavus_, and _Pipistrellus cinnamomeus_ proves to be a species of another genus, _Myotis_ (see Hall and Dalquest, page 583 of this volume).

Genus +Pipistrellus+ Kaup

1829. _Pipistrellus_ Kaup, Skizzirte Entw. -Gesch. u. natuerl. Syst. europ. Thierw., Vol. 1, p. 98, Type, _Vespertilio pipistrellus_ Schreber (not seen by us, after Miller, N. Amer. Fauna, 13: 87, 1897).

_Range in the New World._ -- In North America from southern Canada to Honduras (47 degrees to 5 degrees North Latitude) and from the Atlantic to the Pacific; not recorded from the West Indies or South America.

_Characters._ -- Size small; tail approximately as long as outstretched leg; ears well developed with prominent tragus; dental formula: i.2/3; c.1/1; p.2/2; m.3/3; two upper incisors subequal and outer one lacking a concavity on surface facing canine; dentition otherwise essentially as in _Myotis_ Kaup except that third premolar is always, instead of rarely, absent.

_Remarks._ -- There are two species in North America. Their geographic ranges, as now known, meet, but do not overlap. Certain differences between the two species are listed in the parallel columns below. Most of these differences in the skull and teeth are illustrated in figures 22 and 23 on page 92 of Miller's "Revision of the North American bats of the family Vespertilionidae (N. Amer. Fauna, 13, 1897)."

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Structure _P. hesperus_ _P. subflavus_ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Color Predominately gray Predominately brown -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- - Foot Less than half as long More than half as long as tibia as tibia -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- - Thumb, length of Less than 4.9 mm. More than 4.9 mm. -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- - Tragus Blunt, terminal part Narrow, straight bent forward -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- - Skull Nearly straight Dish-faced (dorsal profile) -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- - Braincase Small Large (viewed from above) -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- - Palate Extending far behind Extending short molars; spine short, distance behind molars; spine long, narrow at base wide at base -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- - I2 Unicuspidate Bicuspidate -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- - I3 Accessory cusp present Accessory cusp absent on anterointernal on anterointernal face face -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- - P1 (occlusal view) Less than a seventh as More than a seventh large as canine as large as canine -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- - P1 (labial view) Concealed by C1 and P4 Not concealed -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- - P4 Touching canine Not touching canine -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- - i3 Touching i2 and c1 Separated by space from i2 and c1 -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- - p3 Lower than anterior As high as anterior cusp of canine cusp of canine -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- - Distance from c1 Less than length of m2; More than length of to m1 premolars crowded m2; premolars less crowded -- -- -- -- -- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -+ -- -- -- -- -- -- -- -- -- -- -- -

+Pipistrellus hesperus+

(Synonomy under subspecies)

_Range._ -- Arid Sonoran life-zones of western North America from Washington southward to Jalisco.