Natalus lanatus Tejedor, 2005

Tejedor, Adrian, 2011, Systematics Of Funnel-Eared Bats (Chiroptera: Natalidae), Bulletin of the American Museum of Natural History 2011 (353), pp. 1-140 : 50-56

Natalus lanatus Tejedor, 2005

Figure 24

Natalus stramineus saturatus: Hall and Dalquest, 1963: 242 . Part; specimen from Fortín, Veracruz, Mexico.

Natalus stramineus mexicanus: Anderson, 1972: 241 . Part; two specimens from two localities in Chihuahua, Mexico .

Natalus stramineus: Rodríguez-Herrera, 2004: 125 . Not Natalus stramineus Gray, 1838 .

Natalus lanatus Tejedor, 2005: 1110 . Type locality ‘‘ 6 miles SSE of Las Varas, Nayarit, Mexico.’’

HOLOTYPE: KU 39628, adult female, skin and skull, collected by J.R. Alcorn on 1 November 1950 (original field number JRA 13312) 6 miles SSE of Las Varas (locality 357 in appendix 1), Nayarit, Mexico. The skin is well preserved and the skull is complete.

PARATYPES: include an adult female (KU 39621) and an adult male (KU 39620), also collected by JRA at the same locality and date as the holotype.

DISTRIBUTION: Mexico (Chihuahua, Durango, Guerrero, Jalisco, Nayarit, Sinaloa, and Veracruz) and Costa Rica (fig. 25).

DIAGNOSIS: A small species of funnel-eared bat (forearm length 16.0– 19.2 mm); legs considerably shorter than forearm; medial margin of ear straight; lateral margin of ear deeply notched; 0–1 folds on lateral margin of ear; nostrils small, opening ventrolaterally; bicolored ventral fur and bicolored or tricolored dorsal hairs; dorsal and ventral hairs always darker at the base than at the tips; pelage dense, woolly, and dull, grayish to ochraceous; ventral surface and more than half of dorsal surface of pinna profusely covered with hairs; legs and feet conspicuously hairy with tufts of long hairs projecting from bases of claws; rostrum shallow in lateral view; premaxilla not inflated; maxilloincisive suture anterior to infraorbital foramen; maxilla dorsal to molars convex, not inflated; sides of postorbital region in dorsal view widely diverging rostrally; palate between pterygoids ending caudally 2/3 of the distance between M3 and tip of pterygoid; posterior margins of maxilla almost perpendicular to longitudinal axis of skull, in ventral view; basisphenoid pit shallow; caudal margin of ascending ramus of mandible perpendicular to alveolar margin of dentary; I1 visible in lateral view, not obscured by I2; mesostylar crest on M3 absent. A comparison of diagnostic characters between N. lanatus , and other species of Natalus is summarized in table 5.

DESCRIPTION: Size small (forearm length 35.4–38.6 mm; greatest skull length 15.0– 16.4 mm; weight 5.0– 6.5 g); muzzle long and not particularly flattened dorsoventrally; nostrils narrowly elliptical, opening ventrolaterally to ventrally on very shallow depression on margin of upper lip; upper lip thickened; lower lip markedly thickened and constricted along dorsal and ventral margin; natalid organ medium size, elliptical and swollen, extending from caudal base of rostrum to crown of head; ears relatively short (12.0– 15.6 mm); ear pinna funnel shaped and broad; pinna with moderately pointed tip; medial margin of pinna straight; lateral margin of pinna moderately concave; three to no small ear ridges along lateral margin of distal pinna; ventral region of ear pinna greatly expanded, covering the eye and tragus in lateral view; medial ear margin thin and flexible; tragus short, lanceolate, and twisted into helixlike structure; tibia (16.0– 19.2 mm) shorter than half the length of the forearm; calcar long and thin, occupying about half the length of the free edge of uropatagium; free margin of uropatagium with fringe of thin hairs; wings broad and relatively short, with 3rd metacarpal (31.2– 33.9 mm) shorter than 5th metacarpal (33.2– 35.5 mm); wings attach to tibia above ankle; pelage dense and woolly; hairs long (8–9 mm, dorsally; 7–8 mm, ventrally); pelage darker dorsally than ventrally; dorsal pelage color from gray (mouse gray) to ochraceous (tawny olive) (pl. 1); dorsal hairs bicolored or tricolored, with dark bases, light middle parts, and medium-dark tips; ventral pelage from gray to ochraceous but hairs markedly bicolored, with bases darker than tips; dense mustachelike hair tufts along lateral margins of upper lip and on dorsum of muzzle; mustache formed by dense, lax, irregularly arranged, and ventrally curved hairs; natalid organ covered with long hairs; ventral face of ears covered with sparse wooly hairs; feet with marked ungual hair tufts at base of claws and fine covering of short erect hairs along tibia; skull long and relatively broad with moderate rostral flexion; rostrum conical, with wide base and tapering tip, with sulcus between nasals almost imperceptible; moderate rostral palatal emargination; maxilla convex above molars; braincase inflated, and elongated; sagittal crest well developed; postorbital constriction wide; maxillary branch of zygomatic arch thin, less deep than twice the height of crowns of last molars; caudal margin of palatal branch of maxilla nearly perpendicular to longitudinal axis of skull; pterygoids nearly parallel; palate extending caudally to more than half the distance between bases and tips of pterygoids; basisphenoid pit shallow; longitudinal medial ridge on basisphenoid present; ectotympanic small, covering less than half of periotic; upper incisors long and pointed; I1 visible in lateral view, not being obscured by I2; occlusal profile of premolars long; upper premolars of similar size; mesostylar crests on M1 and M2 short and straight, mesostylar crest absent on M3; cingular cusp of p4 medium sized and broad; molar cusps relatively broad.

COMPARISONS: Natalus lanatus can be readily distinguished from all other known species of Natalus by its bicolored ventral pelage. The contrast among color bands in ventral pelage may be less noticeable in some individuals, but hair bases are always darker than tips. In all other species of Natalus , the ventral fur is monocolored (with the exception of Natalus jamaicensis , which has slightly lighter ventral hair tips, but the contrast in banding pattern is much less than in N. lanatus ). Natalus lanatus can also be distinguished by its often tricolored dorsal hairs, which are always darker at the base than at the tips. In all other species of Natalidae the light and dark banding pattern of dorsal hairs, when present, is reversed, with the tips always darker than the bases. Natalus lanatus is also distinguishable from all other species in the genus by its hairier legs and feet, with conspicuous ungual tufts (fig. 6). In all other species of Natalus the legs are more sparsely haired and the tips of the toes usually lack long hairs (in cases where long hairs are present at the base of claws, they do not form the dense tufts characteristic of N. lanatus ). In some individuals of N. lanatus , however, the hair tufts at the base of claws may be thin, approaching the condition of the most thickly furred feet of other species of Natalus . Therefore, this character must be used in combination with ventral pelage and cranial characters for an accurate diagnosis of N. lanatus .

In addition to the characters mentioned above, Natalus lanatus differs from the sympatric Natalus mexicanus by its dense, woolly, dull, and often darker pelage, which does not show marked differences in overall darkness throughout the dorsum. The pelage of N. mexicanus is silkier and lax, and when grayish (as in juveniles and young adults), it shows a distinctive patch of dark-tipped hairs posterior to shoulders. From N. mexicanus , N. lanatus is also distinguishable by ear characters (only useful with fluid-preserved and fresh specimens). In N. lanatus the medial margin of the pinna is straight to slightly convex, and the apex of the pinna is relatively broad (the angle formed between the medial and lateral margins of the apex of the pinna in N. lanatus is about 90u). In N. mexicanus , the medial margin of the pinna is slightly concave, forming an angle smaller than 90u with the lateral margin of the pinna, giving the apex a more acutely pointed appearance. The ventral surface of the pinna in N. lanatus is also more densely haired and correspondingly shows a much denser packing of hair follicles than the pinna of N. mexicanus . With regard to body dimensions, the length of the tibia in N. lanatus averages almost 3 mm less than in N. mexicanus , and its overall leg length is considerably smaller than the forearm length. In N. mexicanus , the leg is about as long as or slightly longer than the forearm. Cranially, N. lanatus shows a longer and more anteriorly inflated braincase, and a better-developed sagittal crest than N. mexicanus . In addition, the skull of N. lanatus is slightly but significantly wider than that of N. mexicanus , as reflected by greater averages for zygomatic breadth, breadth across molars, and postorbital breadth. Conversely, the maxillary tooth

row of N. lanatus is slightly shorter than that of N. mexicanus .

VARIATION: Males of Natalus lanatus have a slightly but significantly larger mean breadth across canines than females ( table 14). Bats from the eastern versant of the Mexican highlands (Veracruz) have significantly longer forearms than bats from the western versant (Durango, Jalisco, Nayarit), and have wider skulls (zygomatic breadth, postorbital breadth, P, 0.05; fig. 26). A specimen of N. lanatus from Costa Rica (Río Savegre) is reported to be unusually large relative to N. mexicanus from that country, implying a larger size than in N. lanatus from Mexico (B. Rodríguez, personal commun.).

NATURAL HISTORY AND CONSERVATION: Natalus lanatus is known from 16 localities in Mexico and two in Costa Rica (B. Rodríguez and R.K. LaVal, personal commun.; fig. 25). In five of these localities it has been collected in a roost, of which four have been mines and one a cave. In at least three occasions it has been collected in mistnets (localities 70, 79, and 298). With further inspection of museum collections the number of collection localities of this species in Mexico and Central America will likely increase significantly. One specimen mistnetted in Río Macho, Costa Rica reported as N. stramineus , probably represents N. lanatus (see below).

At its roosts, Natalus lanatus has been found coexisting with Balantiopteryx plicata , Carollia perspicillata , Desmodus rotundus , Glossophaga sp. , Macrotus sp. , Myotis thysanodes , Natalus mexicanus , and Pteronotus parnellii . Large caves or mines are not known from some of the locations where it has been mistnetted (e.g., Rio Savegre, Monte Verde), suggesting that it may often use relatively small cavities as roosts.

The collection localities of Natalus lanatus differ considerably in climatic regimes, ranging from dry mountain subtropical habitats with marked seasonal variations in temperature and precipitation (e.g., La Bufa, Chihuahua; Anderson, 1972), through the zone of transition between pine/oak and tropical deciduous forests (Durango, C. López-González, field notes), to continuously moist montane tropical forest (Orizaba, Veracruz; Hall and Dalquest, 1963). Most of the localities for which geographic coordinates are known with certainty correspond to middle elevations, ranging from 500 to 2000 m. The record from Río Macho, Costa Rica, a wet mountain forest habitat (1300 melevation, 2700 mm annual precipitation) without known caves, most likely corresponds to N. lanatus than to N. mexicanus , given that the latter species has been collected in Costa Rica exclusively in lowland areas with abundant caves.

Natalus lanatus is represented by at least 70 museum specimens. Given that it has been described only recently, many Mexican specimens of N. lanatus identified as N. stramineus (5 N. mexicanus) probably remain in museum collections. This species may be less gregarious than other species of Natalidae . Although it has been collected in moderately large numbers at some localities (e.g., near Tuxpan, Veracruz, locality 445 in appendix 1; and in Ameca, Jalisco, locality 320), over half of the collection localities of this species are represented by a single museum specimen (appendix 1). In addition, it has been collected roosting solitarily in a cave occupied by a colony of Carollia perspicillata ( Hall and Dalquest, 1963) .

Nothing is known of the diet or activity patterns of Natalus lanatus , although it is possible that specimens of this taxon may have served as a basis for natural history accounts of Natalus mexicanus (e.g., Villa-R., 1966). As a representative of the genus Natalus , however, the new species is probably similar in its ecology to other species of the genus (e.g., Natalus primus, Tejedor et al., 2005b ; and Natalus tumidirostris, Linares, 1998 ) in being a slow-flying insectivore that forages through low vegetation. The differences in morphology between N. lanatus and N. mexicanus (see section titled Ecomorphological Diversity), however, may reflect some ecological divergence between these two taxa, as it has been found for other closely related bat species (e.g., Pipistrellus, Barlow et al., 1997 ). Ecological studies of N. lanatus , with a focus on understanding its interaction with its sympatric close relative N. mexicanus , are highly needed.

Natalus lanatus is listed as least concern in the IUCN’s Red List of Threatened Species (IUCN, 2010), but certainly more data is needed from this poorly known species before accurate conservation assessments can be undertaken.

Tables

TABLE 14 Summary of measurementsa of Natalus lanatus

		Females					Males
	N	Mean	(Min.–Max.)	SD	N	Mean (Min.–Max.)		SD
Weight	5	5.4	(5.0–6.0)	0.5	9	5.7	(5.0–6.5)	0.6
Forearm length	24	36.8	(35.4–38.6)	0.9	29	37.0	(35.4–38.3)	0.8
Length of tibia, dry	13	16.5	(15.9–17.3)	0.5	15	16.8	(15.5–18.4)	0.7
Length of tibia	11	17.8	(17.0–18.9)	0.6	15	18.3	(16.0–19.2)	0.8
Length of 3rd metacarpal	5	32.6	(31.2–33.9)	1.0	10	33.0	(32.0–33.8)	0.6
Length of 5th metacarpal	5	34.2	(33.2–35.5)	1.1	10	34.2	(33.2–34.9)	0.4
Length of ear	23	13.9	(13.0–15.3)	0.7	25	14.1	(12.0–15.6)	0.9
Length of penis		–	—	–	10	3.7	(3.1–4.4)	0.4
Length of natalid organ		–	—	–	8	4.3	(2.7–5.3)	0.9
Greatest skull length	13	15.8	(15.3–16.2)	0.3	14	16.0	(15.0–16.4)	0.4
Zygomatic breadth	13	8.1	(7.9–8.3)	0.1	14	8.2	(7.8–8.7)	0.2
Braincase breadth	13	7.7	(7.6–7.9)	0.1	14	7.9	(7.5–8.2)	0.2
Breadth across molars	13	5.4	(5.2–5.5)	0.1	14	5.4	(5.2–5.6)	0.1
Breadth across canines*	13	3.5	(3.4–3.6)	0.1	14	3.6	(3.5–3.8)	0.1
Maxillary tooth row	13	6.5	(6.3–6.8)	0.1	14	6.7	(6.4–6.9)	0.2
Mandibular tooth row	13	6.9	(6.7–7.2)	0.1	13	7.1	(6.9–7.4)	0.1
Postorbital breadth	13	3.2	(3.1–3.3)	0.1	14	3.2	(3.1–3.3)	0.1
Depth of braincase	13	6.3	(6.1–6.5)	0.1	13	6.4	(6.2–6.7)	0.1

a Descriptive statistics of measurements for each sex. N 5 sample size; SD 5 standard deviation. Weight is given in g; all other measurements are given in mm. See text for description of measurement methods. Measurements significantly different between sexes (P, 0.05) are followed by an asterisk (*).