The Alcathoe bat (Myotis alcathoe) is a European bat in the genus Myotis. Known only from Greece and Hungary when it was first described in 2001, its known distribution has since expanded as far as Portugal, England, Sweden, and Russia. It is similar to the whiskered bat (Myotis mystacinus) and other species and is difficult to distinguish from them. However, its brown fur is distinctive and it is clearly different in characters of its karyotype and DNA sequences. It is most closely related to Myotis hyrcanicus from Iran, but otherwise has no close relatives.
With a forearm length of and body weight of , Myotis alcathoe is a small bat. The fur is usually reddish-brown on the upperparts and brown below, but more greyish in juveniles. The tragus (a projection on the inner side of the ear) is short, as is the ear itself, and the inner side of the ear is pale at the base. The wings are brown and the baculum (penis bone) is short and broad. M. alcathoe has a very high-pitched echolocation call, with a frequency that falls from 120 kHz at the beginning of the call to about 43 kHz at the end.
Usually found in old-growth deciduous forest near water, Myotis alcathoe forages high in the canopy and above water and mostly eats flies. The animal roosts in cavities high in trees. Although there are some winter records from caves, it may also spend the winter in tree cavities. Several parasites have been recorded on M. alcathoe. The IUCN Red List assesses Myotis alcathoe as "data deficient", but it is considered threatened in several areas because of its rarity and vulnerability to habitat loss.
Taxonomy The whiskered bat (Myotis mystacinus) and similar species in Eurasia (collectively known as "whiskered bats") are difficult to distinguish from each other; for example, the distantly related Brandt's bat (Myotis brandtii) was not recognised as distinct from M. mystacinus until the 1970s.Niermann et al., 2007, p. 362 Small, unusual M. mystacinus-like bats were first recorded in Greece in the 1970s, but it was not until the advent of genetic studies that these bats could be confirmed as representing a distinct species, named Myotis alcathoe. In 2001, the species was described by German zoologists Otto von Helversen and Klaus-Gerhard Heller on the basis of specimens from Greece and Hungary.von Helversen et al., 2001, p. 217; Voigt et al., 2009 Although it also differs from other whiskered bats by morphological characters, Myotis alcathoe is most clearly distinct in its genetics, including DNA sequences and the location of the nucleolus organiser regions.von Helversen et al., 2001, p. 218 Two studies used microsatellite markers on European whiskered bats: the first one used western European samples and recovered three well-defined species clusters for M. alcathoe, M. brandtii and M. mystacinus;Jan et al., 2010 the other one, conducted in Poland, suggesting a high level of hybridisation with other whiskered bats that would further complicate attempts to identify M. alcathoe morphologically.
Von Helversen and Heller argued that none of the old names now considered synonyms of M. mystacinus could apply to M. alcathoe, because these names all have their type localities in western or central Europe. However, the more recent discovery of M. alcathoe further to the west renders it possible that an older name may be discovered.Ruedi et al., 2002, p. 648; Benda et al., 2003a, p. 364 In addition, Russian researcher Suren Gazaryan has suggested that the name caucasicus Tsytsulina, 2000 (originally proposed for a subspecies of M. mystacinus from the Caucasus) may prove to be applicable to M. alcathoe; in that case, the species would be renamed Myotis caucasicus. However, a later analysis instead attributed the name caucasicus to the eastern species Myotis davidii.Benda et al., 2016, p. 858 M. alcathoe may have remained undetected in Germany for so long because bat researchers did not sample its preferred habitats and would dismiss unusual-looking whiskered bats as being abnormal M. mystacinus or M. brandtii.
On the basis of mitochondrial DNA sequence analysis, Myotis alcathoe first appeared close to Geoffroy's bat (Myotis emarginatus) of southern Europe, North Africa, and southwestern Asia.von Helversen et al., 2001, fig. 2; Mayer et al., 2007, fig. 1 However, a study of the mitochondrial cytochrome b gene incorporating many Myotis species did not support this relationship, and could not place M. alcathoe securely at a specific position among Eurasian Myotis.Stadelmann et al., 2004, pp. 187–188 In 2012, a closely related species, Myotis hyrcanicus, was described from Iran. It is morphologically difficult to distinguish from M. alcathoe, but sufficiently distinct genetically to be considered a separate species.Benda et al., 2012, p. 338
The population of Myotis alcathoe in Krasnodar Krai on the Russian Black Sea coast is genetically distinct from populations in the rest of Europe and is accordingly recognised as a subspecies, Myotis alcathoe circassicus, first named in 2016.Benda et al., 2016, p. 859 Within the remaining populations (subspecies Myotis alcathoe alcathoe), two groups with slightly divergent mitochondrial DNA sequences (separated by 1.3 to 1.4% sequence divergence) are distinguishable within the species, which probably correspond to different glacial refugia where M. alcathoe populations survived the last glacial period. One, known as the "Hungarian" group, has been recorded from Spain, France, Austria, Hungary, and Slovakia, and probably corresponds to a refugium in Iberia; the other, the "Greek" group, is known only from Greece and Slovakia.Spitzenberger et al., 2008, p. 7
The specific name, alcathoe, refers to Alcathoe, a figure from Greek mythology who was turned into a bat when she refused the advances of the god Dionysus. She was associated with gorges and small streams, the preferred habitat of Myotis alcathoe in Greece.von Helversen et al., 2001, p. 217 In their original description, von Helversen and colleagues described her as a nymph, and the common name "nymph bat" has therefore been used for this species.Dietz and von Helversen, 2004, p. 71; Benda, 2008, p. 107 However, none of the classical sources speak of Alcathoe as a nymph; instead, she was a princess, the daughter of King Minyas of Orchomenos. Therefore, Petr Benda recommended in 2008 that the common name "Alcathoe bat" or "Alcathoe myotis" be used instead.Benda, 2008, p. 107 Other common names include "Alcathoe's bat"Dietz and von Helversen, 2004, p. 71 and "Alcathoe whiskered bat". The name of the subspecies M. a. circassicus refers to Circassia, a historical region of the northwestern Caucasus.Benda et al., 2016, p. 860
Description
Myotis alcathoe is the smallest European Myotis species. The fur is brownish on the upperparts, with a reddish tone in old specimens, and a slightly paler grey-brown below. Younger animals may be completely grey-brown.von Helversen et al., 2001, p. 218; Dietz and von Helversen, 2004, p. 42; Agirre-Mendi et al., 2004, pp. 53–54 The brown fur distinguishes adult M. alcathoe from other whiskered bats, but juveniles cannot be unambiguously identified on the basis of morphology.Spitzenberger et al., 2008, p. 9 M. alcathoe is similar to Daubenton's bat (Myotis daubentonii) and M. emarginatus in colour.Benda et al., 2003a, p. 362 On the upper side of the body, the hairs are 6 to 8 mm long and have dark bases and brown tips. The hairs on the lower side of the body are only slightly paler at the tip than at the base.
The face and the upper lips are reddish to pink, not dark brown to black as in M. mystacinus.Pavlinić et al., 2012, p. 331; Bogdanowicz et al., 2012, table 1 Although most of the face is hairy, the area around the eyes is bare. The nostrils are heart-shaped,Dietz and von Helversen, 2004, p. 42 and their back end is broad, as in M. brandtii, not narrow as in M. mystacinus.von Helversen, 2001, p. 1161 Several glands are present on the muzzle, most prominently in reproductively active males. The ears are brown and are lighter on the inside than the outside. There is a notch at the edge of the ear, and the pointed tragus (a projection inside the ear that is present in some bats) extends up to this notch; the tragus is longer, extending beyond the notch, in both M. brandtii and M. mystacinus.Bogdanowicz et al., 2012, table 1 The base of the inner side of the ear is white; it is much darker in M. mystacinus.Alcalde, 2010, p. 232; Agirre-Mendi et al., 2004, p. 54; Ruedi et al., 2002, p. 647 The feet and the thumbs are very small. The small size of the ear, tragus, feet, and thumb distinguishes M. alcathoe from the slightly larger M. mystacinus and M. brandtii, but the feet are relatively larger than in M. mystacinus.Ruedi et al., 2002, p. 647
The wings are brown, but lighter than those of M. mystacinus.von Helversen, 2004, p. 1162 The plagiopatagium (the portion of the wing between the last digit and the hindlegs) is attached to the fifth toe. The tail extends only about 1 mm beyond the back margin of the uropatagium (the portion of the wing membrane between the hindlegs). The calcar, a cartilaginous spur supporting the uropatagium, is slender. With a width around 1.3 mm, the penis is narrow, and it lacks a broadened tip (except in one Croatian specimen).Pavlinić et al., 2012, p. 333 The baculum (penis bone) is about 0.5 mm long. The short and broad shape of this bone distinguishes M. alcathoe from M. brandtii as well as M. ikonnikovi.von Helversen, 2004, p. 1161; von Helversen et al., 2001, p. 218
The skull is similar in shape to that of M. mystacinus and M. brandtii, but the front part of the braincase is higher. The second and third upper premolars (P2 and P3) are tiny and pressed against the upper canine (C1) and fourth premolar (P4). The canine is less well-developed than in M. mystacinus. There is a clear cusp present on the side of the P4. The accessory cusp known as the protoconule is present on each of the upper molars when they are unworn. M. mystacinus lacks the P4 cusp and the protoconules on the molars, but M. brandtii has an even larger cusp on P4. The Caucasus subspecies, M. alcathoe circassicus, has a relatively narrower skull and longer upper molars.
As usual in Myotis species, M. alcathoe has a karyotype consisting of 44 chromosomes, with the fundamental number of chromosomal arms equal to 52. However, a 1987 study already found that M. alcathoe (then called "Myotis sp. B") differs from both M. mystacinus and M. brandtii in the pattern of active nucleolus organiser regions on the chromosomes. M. alcathoe also differs from other Myotis species in the sequences of the mitochondrial genes 12S rRNA and NADH dehydrogenase subunit 1 by at least 5% and 13%, respectively.von Helversen et al., 2001, pp. 219–220
M. alcathoe has the highest-frequency echolocation call of any European Myotis. In open terrain, the call has an average duration of 2.5 ms, but it may be up to 4 ms long. At the beginning, its frequency is around 120 kHz, but it then falls fast, subsequently falls slightly slower, and at the end falls faster again. The call reaches its highest amplitude at around 53 kHz.von Helversen et al., 2001, pp. 221–222 It terminates at around 43 to 46 kHz; this characteristic is especially distinctive.Dietz et al., 2007, p. 231 In different experiments, the time between calls was found to be around 85 and 66 ms, respectively.von Helversen, 2004, p. 1167 The high-pitched call may be an adaptation to the animal's occurrence in dense vegetation.Ohlendorf and Funkel, 2008, p. 109
The head and body length is about , and the wingspan around .von Helversen, pers. comm. in Skiba, 2003, p. 107 Forearm length is , tibia length is , hindfoot length is , and body weight is .Dietz et al., 2007, p. 230 In the subspecies M. a. circassicus, the forearm length is and ear length .
Distribution and habitat