class="ctrspace c1">Genus Lasiurus Gray

Hairy-tailed Bats

Provisional Key to the Recent Species of Lasiurus

• 1.  Color reddish or grayish (not yellowish); normally two premolars on each side of upper jaw.
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• 2.  Occurring on Antillean islands (color reddish).
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• 3.  Length of upper tooth-row less than 4.5 mm. (occurring on Hispaniola and Bahamas)L. minor.
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• 3'. Length of upper tooth-row more than 4.5 mm. (not occurring on Hispaniola and Bahamas).
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• 4.  Greatest length of skull less than 13.9 mm. (occurring on Cuba)L. pfeifferi.
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• 4'. Greatest length of skull more than 13.9 mm. (occurring on Jamaica)L. degelidus.
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• 2'. Occurring on mainland and coastal islands of North and South America; also on Galapagos and Hawaiian islands (color reddish or grayish).
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• 5.  Total length more than 120 mm.; color grayishL. cinereus.
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• 5'. Total length less than 120 mm.; color reddish.
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• 6.  Upper parts brick red to rusty red, frequently washed with white; lacrimal ridge present.
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• 7.  Not occurring on Galapagos IslandsL. borealis.
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• 7'. Known only from Galapagos Islands (both ear of 7.6 mm. and thumb of 6.4 mm. allegedly shorter than in L. borealis of adjacent mainland; presence of lacrimal ridge not verified)L. brachyotis.
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• 6'. Upper parts not brick red to rusty red; lacrimal ridge not developed.
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• 8.  Forearm more than 46.5 mm. (48 in only known specimen, a male); dorsum bright rufous (absence of lacrimal ridge not verified)L. egregius.
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• 8'. Forearm less than 46.5 mm.; dorsum not bright rufous.
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• 9.  Upper parts mahogany brown washed with white; forearm less than 43 mmL. seminolus.
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• 9'. Upper parts deep chestnut; forearm more than 43 mm. (44.8 in only known specimen, a female)L. castaneus.
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• 1'. Color yellowish; only one premolar on each side of upper jaw.
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• 10.  Total length more than 119 mm.; length of upper tooth-row 6.0 mm. or moreL. intermedius.
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• 10'. Total length less than 119 mm.; length of upper tooth-row less than 6.0 mmL. ega.

Lasiurus intermedius

Northern Yellow Bat

Distribution and Geographic Variation

Lasiurus intermedius H. Allen, type from Matamoros, Tamaulipas, has been reported from the Rio Grande Valley of Texas southward to Honduras and in Cuba. Lasiurus floridanus (Miller), type from Lake Kissimmee, Florida, has been recorded from southeastern Texas, eastward along the Gulf of Mexico to Florida, and thence northward along the Atlantic Coast to extreme southeastern Virginia (see records of occurrence beyond and Fig. 2). Specimens of intermedius from the vicinity of the type locality and from other localities in México differ from specimens of floridanus (from Florida and southern Georgia) as follows: Larger, both externally (especially forearm) and cranially (see measurements); teeth larger and heavier; skull heavier and having more prominent sagittal and lambdoidal crests; braincase less rounded, more elongate; auditory bullae relatively smaller; upper parts averaging brighter (yellowish to yellowish-orange in general aspect, rather than yellowish-brown to brownish-gray).

The differences mentioned above are of the magnitude of those that ordinarily separate subspecies of a single species rather than two species. Miller (1902:392-393), in the original description of floridanus, noted that the differences between it and intermedius were slight and remarked (p. 393): "Indeed, it is probable that it intergrades with the Texas animal." Lowery (1936:17) also has suggested that intergradation might occur between intermedius and floridanus "in southwestern Louisiana or eastern Texas"; later (1943:223-224) he pointed out that specimens from Baton Rouge, Louisiana, averaged larger in cranial dimensions than typical floridanus and again mentioned the possibility of intergradation between the two kinds. Sanborn (1954:25-26) touched obliquely on the problem when he wrote: "In Florida, Dasypterus intermedius is referred to as a Florida yellow bat (Dasypterus floridanus)." Handley (1960:478) wrote that certain morphological similarities suggested "gene flow" between the two kinds.

Specimens examined from Louisiana resemble floridanus from Georgia and Florida to the eastward in external dimensions. Some of those specimens resemble floridanus in size of skull, but two skulls from Louisiana are inseparable from those of topotypes of intermedius. The upper parts of specimens from Louisiana are