Micronycteris minuta (P. Gervais, 1856)
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https://doi.org/ 10.5281/zenodo.6458594 |
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https://doi.org/10.5281/zenodo.6762004 |
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persistent identifier |
https://treatment.plazi.org/id/03A687BC-FFB7-FFB6-1692-FE06FBC4F56C |
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Plazi |
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Micronycteris minuta |
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4. View Plate 35: Phyllostomidae
Tiny Big-eared Bat
Micronycteris minuta View in CoL
French: Micronyctere menu / German: ZwerggroRohrblattnase / Spanish: Micronicterio menudo
Other common names: White-bellied Big-eared Bat
Taxonomy. Schizostoma minutum P. Gervais View in CoL in Castelnau, 1856,
“Capella-Nova,” Minas Gerais, Brazil.
In 1900, J. A. Allen described the species M. hypoleuca with type locality of Bonda, Santa Marta, Colombia. Later, in 1949, C. C. Sanborn suggested that M. hypoleuca could be recognized as a subspecies of M. minuta . In 1996, N. B. Simmons confirmed that M. minuta includes M. hypoleuca, after examining holotype of the latter.
Meanwhile, in 1967, P. Pirlot described M. megalotis homezi , based on three specimens from the north-western region of Maracaibo, Venezuela. Simmons and R. S. Voss in 1998 elevated M. megalotis homezi to a full species. J. Ochoa and J]. Sanchez in 2005 showed that development of a cutaneous fossa behind interauricular band also exists in other species of Micronycteris such as M. minuta , M. microtis , and M. megalotis but with distinct degrees of development. As a consequence, M. homezi was considered a Junior synonym of M. minuta . Finally, C. A. Porter and collaborators in 2007, based on phylogenetic analysis, recognized four primary lineages within Micronycteris , proposing them as subgenera. The new subgenus Schizonycteris includes M. minuta , M. schmidtorum , and M. sanborni . In concordance with this work, L.. Siles and collaborators in 2013 suggested that M. minuta might have underestimated or cryptic diversity. Monotypic.
Distribution. Widely distributed in Central and South America, from extreme E Guatemala (Sierra del Caral) and Honduras to Colombia, Venezuela, the Guianas, Ecuador, E Peru, Brazil, and Bolivia; also on Trinidad I. View Figure
Descriptive notes. Head-body ¢.42-58 mm, tail 7-15 mm, ear 17-24 mm, hindfoot 7-14 mm, forearm 31-3-40-5 mm; weight 5-8-5 g. The Tiny Big-eared Bat is one of the smaller species of Micronycteris . Greatest lengths of skulls are 17-3-21-9 mm. Dorsal pelage is pale brown to blackish brown, with pale white bases comprising one-half to two-thirds of hair length in most individuals. Hairs near shoulders are 4-8 mm long. Ventral fur is gray-brown or gray to almost white, although rarely true white as seen in Sanborn’s Big-eared Bat ( M. sanborni ). Pelage of the Tiny Big-eared Batis slightly buffy or hazel on sides, with pale white bases comprising one-fourth to one-half of hair length. Ventral fur clearly contrasts with dorsal fur. Hairs of underparts are 3-5 mm long. Some specimens from Brazil and Ecuador have variations of orange tones in ventral fur. There is a report of a completely albino female in a group offive individuals caught in San José, Costa Rica in 2004. Uropatagium and base oftail are naked. Wings are relatively short, and membranes are attached on ankles or extremity oftibias. Second phalanx of fourth digit is subequal to first phalanx. Tail slightly protrudes from upper section of uropatagium. Calcar is mostly shorter than foot, sometimes similar in length. Upperlip has a few white translucent hairs, in contrast to other members of the subgenus that lack them entirely. As other species of Micronycteris , ears are large and rounded, and they are connected across head by relatively high interauricular band with deep central notch that divides membrane into two notorious triangular skin lappets with naked swollen borders. Anterior surfaces of lappets have short and dense fur; posterior surfaces have distinguishable tufts of hairs. Hairs on medial border of pinna are short (less than 3 mm) and dense. Male Tiny Big-eared Bats have cutaneous fossa behind interauricular band; this structure resembles a depression in the head, with an internal semicircular surface (4-5 mm diameter), formed by smooth, naked and translucent membranous surface and surrounded by thick cutaneous edge, sometimes with wrinkled appearance. Peripheral dense and stiff hairs are directed to center of fossa. Developmentof fossa apparently is related to age. In young males, stage one of development is characterized by cutaneousfossa with inconspicuous border with fringe of soft hairs; interauricular band shows modest development, with naked and moderately swollen lappets. Stage two of development is characterized by better-defined border of fossa, mostly naked, with fringe ofstiff, coarse, whitish, 4-5 mm long hairs. In stage three of development, fossa shows maximum depth and extension due to high growth of surrounding border, which also develops small wrinkles or folds on its anterior surface; hairs are also stiff, coarse, whitish, and 4-5 mm long. In this last stage, interauricular band is highly hypertrophied, with skin lappets c¢. 5 mm high and thick border that is a prolongation of interauricular band and whosetissue contains cartilaginous plaque and striated muscle fibers, suggesting capability of movement, control of fossa inner surface exposure, and regulation of sebaceous substances. Histological analysis of posterior fossa revealed that it has no sebaceous cells; interauricular band is responsible for production of glandular substances. Gradual hypertrophy of band would result from accumulation of sebaceous cells. Ochoa and Sanchez in 2005 suggested that these secretions were related to differential social interactions and male hierarchy. Skull is narrow and elongated; braincase is domed, with little or no development of sagittal crest. Mastoid breadth is greater than zygomatic breadth in most specimens. Dental formula of all species of Micronyeterisis 1.2/2, C 1/1, P 2/5. M 3/3 (x2) = 34. Shape and presence of lobes in upperincisor of the Tiny Big-eared Bat are variable, although mostly bilobed; lower incisors are small and bilobed. To preserve phylogenetic information ofteeth,letter-number symbols are used; for example,in this genus, positional upperfirst premolaris noted as P?, given that original P' is considered a missing tooth during diversification of the group. P? is visibly shorter than the P*—about the same height in the Little Big-eared Bat ( M. megalotis ) and the Common Big-eared Bat ( M. microtis ); P, slightly larger and taller than P,; and P,is tiny, much smaller than P, and P,. Chromosomal complement has 2n = 28 and FN = 50 or 52.
Habitat. Mostly evergreen, dry, and deciduous tropical forests from low to mid-elevations (less than 1600 m) and more frequently below 900 m. The Tiny Big-eared Bat also occurs near streams and in swampy areas, cloud forests, orchards, pastures, clearings, croplands (banana groves), yards, lawns, and gardens in the vicinity of human settlings.
Food and Feeding. The Tiny Big-eared Bat is a gleaning insectivore. Its diet is composed of insects, predominantly Hemiptera , Coleoptera , and Lepidoptera . Analyses from stomach contents in Costa Rica and Panama detected vegetative material, so it has been suggested that fruits can be important food items.
Breeding. In south-eastern Brazil, pregnant Tiny Big-eared Bats were caught in September and one lactating female in February. In Trinidad, one pregnant female, two lactating females, and two females nursing young were caught in May. There are also records of pregnant females in March, one containing a 17mm embryo, and a reproductively active male in July in Costa Rica. There are records from Suriname of a lactating female and a reproductive male in September.
Activity patterns. The Tiny Big-eared Bat is nocturnal.
Movements, Home range and Social organization. The Tiny Big-eared Bat has been found in large caves with Seba’s Short-tailed Bat ( Carollia perspicillata ), the Little Bigeyed Bat ( Chiroderma trinitatum ), the Woolly False Vampire Bat ( Chrotopterus auritus ), the Common Vampire Bat ( Desmodus rotundus ), the White-winged Vampire Bat ( Diaemus youngii ), Pallas’s Long-tongued Bat ( Glossophaga soricina ), Handley’s Nectar Bat ( Lonchophylla handleyi ), the Little Big-eared Bat ( Micronycteris megalotis ), the Greater Spear-nosed Bat ( Phyllostomus hastatus ), Parnell’s Common Mustached Bat ( Pteronotus parnellii), and Wagner’s Lesser Mustached Bat ( P. personatus ). It has been recorded in hollow trees roosting with Greater Sac-winged Bats ( Saccopteryx leptura ), Little Bigeared Bats, Heller's Broad-nosed Bats ( Platyrrhinus helleri ), and Seba’s Short-tailed Bats.
Status and Conservation. Classified as Least Concern on The IUCN Red List.
Bibliography. Allen (1900), Andersen (1906a), Ascorra, Wilson & Romo (1991), Baker (1973), Brosset & Charles-Dominique (1991), Feijo, Rocha & Ferrari (2015), Fleming et al. (1972), Gamba-Rios (2010), Gardner (1977b), Gardner et al. (1970), Genoways & Williams (1979), Goodwin & Greenhall (1961), Graham (1988), Handley (1976), Larsen et al. (2011), Lopez-Gonzéalez (1988a), Nogueira, Peracchi & Moratelli (2007), Ochoa & Sanchez (2005), Pérez-Consuegra et al. (2017), Pirlot (1967), Porter et al. (2007), Rengifo et al. (2013), Sanborn (1949a), Siles et al. (2013), Simmons (1996), Simmons & Voss (1998), Simmons et al. (2002), Simoes (2012), Teixeira & Peracchi (1996), Whitaker & Findley (1980), Williams & Genoways (1980a).
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