|A drawing by Ángel Cabrera, showing a ventral view of the entire animal, with one wing folded and the other spread; a lateral view of the head; and a view of the inner side of the ear|
Although the species was first named in 1904, it was included in Natterer's bat (Myotis nattereri) until molecular studies, first published in 2006, demonstrated that the two are distinct species. M. escalerai is most closely related to an unnamed species from Morocco. Unlike M. nattereri, which lives in small groups in tree holes, M. escalerai forms large colonies in caves. Females start to aggregate in late spring in maternity colonies, and their young are born in summer. The species spends each winter in hibernation colonies, usually in caves or basements.
M. escalerai is a medium-sized, mostly gray bat, with lighter underparts. It has a pointed muzzle, a pink face, and long ears. The wings are broad and the species is an agile flyer. Wingspan is 245 to 300 mm (9.6 to 11.8 in) and body mass is 5 to 9.5 g (0.18 to 0.34 oz). Though very similar to M. nattereri, it differs from that species in some features of the tail membrane. The conservation status of M. escalerai is assessed as "Vulnerable" or "Data Deficient" in various parts of its range.
Myotis escalerai was named by Ángel Cabrera in 1904, on the basis of four specimens from two localities in eastern Spain. He named the new species after the Spanish entomologist Manuel Martínez de la Escalera, who collected two specimens of the species in Bellver, Catalonia. Cabrera did not designate either of the two localities (Bellver and Foyos, Valencia) as the type locality, and later authors have listed both. Currently, Foyos, which was listed first by Cabrera, is accepted as the type locality. Cabrera commented that M. escalerai was close to Natterer's bat (Myotis nattereri), and in 1912, Gerrit S. Miller listed escalerai as a synonym of that species. He argued that one of the features Cabrera had listed as distinguishing the two was an artefact of the preservation of the specimens of M. escalerai in alcohol. Miller's classification was followed for almost a century, and indeed, Cabrera himself accepted in 1914 that M. escalerai was not a valid species.
|Relationships in the Myotis nattereri complex based on nuclear and mitochondrial DNA sequences|
However, a 2006 study by Carlos Ibáñez and colleagues found that M. nattereri in fact included several cryptic species with highly distinguished DNA sequences characteristics, even though morphological differences were small or nonexistent. One, which they recorded in the southern Iberian Peninsula, was identified as M. escalerai. Populations in the mountains of northern Spain represent another species (now known to be Myotis crypticus), which is now also known from the Alps. A 2009 study using data from the mitochondrial genes cytochrome b and ND1 found that M. escalerai is most closely related to an unnamed species from Morocco previously included in M. nattereri (now known to be Myotis zenatius), and more distantly to other members of the Myotis nattereri group. M. escalerai and M. zenatius are estimated to have diverged about 2 million years ago. Later in 2009, M. escalerai was also recorded for the first time from France. One 2011 study found a fifth putative species in the complex ("Myotis sp. C"), occurring in the Italian peninsula and most closely related to M. crypticus, but another study published in the same year included these populations in M. crypticus. The latter study, by I. Salicini and colleagues, used sequences from six nuclear genes to confirm the distinctiveness of M. escalerai and its close relationship with M. zenatius.
A medium-sized gray bat, Myotis escalerai is similar to Myotis nattereri. The fur is long and soft; with a brown tone on the back, and the brighter underparts approaching white. The feet are dark gray. Much of the face is pink, and the muzzle is pointed, with long hairs on the upper lip resembling a moustache. The long ears are brown to gray. The tragus, a projection on the inner side of the outer ear, is long and reaches to the middle of the ear and colored gray to yellow, becoming darker from the base towards the tip. According to several authors, it differs from M. nattereri in showing a distinct fringe of hairs on the tail membrane, but bat specialist A.M. Hutson writes that this feature does not distinguish the two species. In addition, the presence of an S-shaped spur on the uropatagium (membrane between the hind legs), which approaches the middle of the membrane, is a distinctive feature of this species. With its broad wings, low flight, and rapid wingbeats, the species is capable of precise, agile flight.
The head body length is 42 to 50 mm (1.7 to 2.0 in), tail length is 38 to 47 mm (1.5 to 1.9 in), forearm length is 35 to 43 mm (1.4 to 1.7 in), ear length is 14 to 18 mm (0.55 to 0.71 in), wingspan is 245 to 300 mm (9.6 to 11.8 in), and body mass is 5 to 9.5 g (0.18 to 0.34 oz).
The range of Myotis escalerai remains poorly constrained and may turn out to be larger than currently known. M. escalerai is widespread in Spain and Portugal. For example, it occurs widely, though localized, in Aragón, where Myotis sp. A (the only other species in the M. nattereri complex to occur there) is known from a single locality only. Similarly, in Catalonia, M. escalerai is widespread and occurs from sea level up to an altitude of 1,500 m (4,900 ft). The species also occurs on the Balearic Islands of Mallorca, Menorca, and Ibiza. The sole French record is from a cave in Valmanya, Pyrénées-Orientales.
Relatively little is known of the biology of M. escalerai. Females begin to form reproductive colonies in April and May, either small ones or larger aggregations that may also contain males. However, most males remain solitary in this period, although some also form colonies. The single young is born in June or July and becomes independent after some six weeks. Mating usually takes place in fall, but sometimes in winter. The formation of large reproductive colonies in caves, which may consist of several hundreds of individuals, distinguishes M. escalerai from M. nattereri as well as M. sp. A, which roost in smaller groups in tree holes. In Aragón, colonies contain 50 to 880 individuals, and Catalan colonies are known to contain over a hundred bats. Reproductive colonies may be formed in a variety of structures, including caves, mines, tree holes, and human-made structures such as bridges and houses. However, hibernation colonies need constant temperatures between 0 and 5 °C (32 and 41 °F), and are usually located in caves or basements. M. escalerai is considered a sedentary species, and does not usually migrate over long distances, although it does move between reproduction and hibernation colonies. Rabies has been identified in a Spanish specimen of M. escalerai.
The IUCN Red List classifies Myotis escalerai as "least concern". M. nattereri and M. escalerai are also listed separately on the Annex to the Agreement on the Conservation of Populations of European Bats. Portugal lists M. escalerai as "vulnerable", though noting that populations may be increasing. Because of its restriction to caves, it is considered vulnerable in Aragón. In Catalonia, the species appears tolerant of different habitats and of human disturbance, but it is listed as "data deficient". In France, where the species was only discovered in 2009, it is also listed as "data deficient".