In terms of its zoological diversity, Europe is the best known continent on the planet. Indeed it’s generally assumed that just about all of Europe’s macrofauna has, by now, been discovered. While that’s mostly true, it seems that at least a few species – so called ‘cryptic species’ – have been missed, mostly because they’re extremely similar to their close relatives.
Here, I want to look
briefly at new discoveries made concerning the diversity of European microbats [composite above shows, clockwise from top left: Pipistrellus pipistrellus, Plecotus auritus, Pl. austriacus and Myotis nattereri. All photos from wikipedia]. Because bats are typically small and difficult to observe at close range, and because species may distinguish one another by auditory cues rather than visual ones, it now seems that many species very similar in appearance to others had been mostly ‘missed’ by traditional classifications. What typically happens in the discovery of a ‘cryptic species’ is that (1) molecular data first brings attention to its existence (often because it appears as distinctly separate on a phylogeny); (2) it’s then discovered or realised that morphological features support its distinction as well; (3) a description mentioning these (sometimes diagnostic) morphological features – sometimes published decades earlier – is found to exist, and it often includes a binomial for the ‘newly discovered’ hitherto cryptic taxon; and (4) it’s reaffirmed that neither molecular nor morphological data alone can satisfy everyone of the reality of said cryptic species, but that things are most convincing when data from both sources is combined.
While most European bat species were formally named in the 1800s and before, recent work has shown that quite a few cryptic species can and do warrant recognition. In fact about 15 ‘new’ European vesper bats (‘vesper bats’ = those in the huge microbat group Vespertilionidae) have been named or resurrected from synonymy in recent decades. Readers with exceptional memories might realise that the text you’re reading here is a much-modified version of a rant I published on Tet Zoo ver 1 in 2006: this was a response to the perplexing and flat wrong statement that the Cypriot mouse Mus cypriacus [shown here] was “the first new European mammal to be discovered in 100 years”.
When it comes to the subject of recently discovered cryptic microbats, many people might immediately think of the two pipistrelle species dubbed informally the 45 and 55 kHz pipistrelles (or Common and Soprano pipistrelles), for in 1993 it was discovered that the ‘species’ Pipistrellus pipistrellus actually consisted of two distinct species, both of which differed in the echolocation frequencies of their calls. Later work showed that they differ in genetics, morphology and behaviour (Barlow et al. 1997, Davidson-Watts & Jones 2006). However, while the many differences between these two species have only recently been acknowledged, both were originally named during the 1700s and 1800s: the 45 kHz/Common pipistrelle is P. pipistellus (Schreber, 1774) while the 55 kHz/Soprano pipistrelle is P. pygmaeus Leach, 1825. Recent molecular work indicates that even the new, revised version of the Common pipistrelle consists of more than one species (Mayer et al. 2007).
Two long-eared bats no more: make that three.. four.. five.. six… seven?
Other vesper bat groups have yielded new European species comparatively recently, though as we’ll see a few of them are of controversial status. For much of the 20th century there were thought to be just two species of long-eared bat (Plecotus) in Europe: the Brown long-eared bat P. auritus (Linnaeus, 1758) and Grey long-eared bat P. austriacus (Fischer, 1829). Recent discoveries and proposals mean that there are now as many as seven, three of which occur in close proximity in the Alpine region.
Among the best understood of these is P. macrobullaris Kuzjakin, 1965, named for Swiss and Austrian long-eared bats previously regarded as intermediate between Brown long-eared bats and Grey long-eared bats (it’s now known from Croatia and elsewhere, and seems to be widespread across continental Europe). Spitzenberger et al. (2001, 2006) confirmed via molecular analysis that P. macrobullaris is worthy of species status. Like other cryptic species, it can often be diagnosed morphologically once you know what to look for: unlike other European long-eared bats, it has a small, triangular pad on its lower lip [shown here, from Tvrtković et al. 2005]. However, Ashrafi et al. (2010) noted that the pad was sometimes difficult to spot in some individuals due to its size and colour. In fact, these authors showed that many of the external morphological characters recently proposed to allow differentiation of the different long-eared bats (like fur colour and penis shape) are often unreliable: Ashrafi et al. (2010) did show, however, that comparisons of external measurements allowed the species to be distinguished extremely reliably.
A more recently named supposed species from Austria – P. microdontus Spitzenberger et al. 2002 – seems to be synonymous with P. macrobullaris (see Juste et al. 2004, Spitzenberger et al. 2006).
Also recently named is the Alpine long-eared bat P. alpinus Kiefer & Veith, 2001, named for a specimen collected in France in 2001 (Kiefer & Veith 2001) but later reported from Greece, Liechtenstein, Austria, Croatia and Switzerland [P. alpinus photo shown here by A. Kiefer, from Kiefer & Veith (2001)]. The Croatian specimen was collected in 1972 and the specimen from Liechtenstein in 1961: a reminder that the actual ‘discovery’ date of a species often doesn’t match the time when it becomes technically named and/or described. P. alpinus also now seems to be synonymous with P. macrobullaris (see Juste et al. 2004, Spitzenberger et al. 2006). However, a high degree of mtDNA variation in P. macrobullaris has led to the suggestion that it might contain cryptic species (Mayer et al. 2007), and it’s possible that ongoing work will show that these cryptic taxa – if they warrant recognition – correspond to P. microdontus or P. alpinus.
In 2002, another new one – the Sardinian long-eared bat P. sardus Mucedda et al., 2002 [shown below; photo by Mauro Mucedda, from wikipedia] – was described from Sardinia. Local bat experts had long thought that these Sardinian bats were morphologically distinctive compared to other European long-eared bats, but their suspicions were only confirmed after molecular results were obtained. P. sardus seems to be more closely related to the Brown long-eared bat than to species like P. macrobullaris, and it’s said that it can be identified in the hand thanks to the proportional size of its tragus, foot and thumb (among other features).
Several additional new long-eared bat taxa have also been named within the last few decades: originally named as subspecies, new data has caused some of them to be elevated to species level. Within P. auritus, the subspecies P. a. hispanicus (later reidentified as a subspecies of P. austriacus) was named in 1957, P. a. kolombatovici in 1980, and P. a. begognae in 1994. Genetic studies have since shown that both P. a. kolombatovici from Croatia and P. a. begognae from the Iberian Peninsula are distinct enough to be regarded as full species (Mayer & von Helverson 2001, Spitzenberger et al. 2001, Mayer et al. 2007), though the latter taxon is not widely accepted at the moment.
Another form first named as a subspecies of P. auritus, P. a. teneriffae Barret-Hamilton, 1907 was elevated back to species status in 1985 (see also Spitzenberger et al. 2006). Though originally named as a Canary Islands endemic, bats referred to this species were later reported from north Africa and the Balkans. However, it now seems that they belong either to P. kolombatovici or P. austriacus.
The final list of currently recognised species is therefore P. auritus, P. austriacus, P. kolombatovici, P. macrobullaris, the Sardinian endemic P. sardus, and the Canary Islands endemic P. teneriffae. Incidentally, north African bats until recently included in P. kolombatovici are now regarded as distinct enough for their own species: P. gaisleri Benda et al., 2004.
New mouse-eared bats aplenty?
Another new vesper bat, this time a mouse-eared bat (= Myotis), was named during the 1970s but now seems unlikely to be a valid species. It’s the Nathaline bat Myotis nathalinae Tupinier, 1977, described for two specimens from Ciudad Real in Spain. However, it’s highly similar genetically and morphologically to Daubenton’s bat M. daubentonii (Tupinier 1977). Indeed Bogdanowicz (1990) found that the skull morphology of M. nathalinae fell within the range of variation exhibited by M. daubentonii populations, and therefore argued against the idea that it should be regarded as a valid species. Genetic samples of M. nathalinae have also fallen within the range of variation exhibited by M. daubentonii (Mayer & von Helverson 2001). Other studies have produced the same result, so bat workers generally regard M. nathalinae as a subspecies of M. daubentonii.
Alcathoe bats everywhere!
A second new mouse-eared bat, M. alcathoe von Helverson et al., 2001, is morphologically and genetically distinct, and noteworthy in being Europe’s smallest mouse-eared bat, and the one with the most high-pitched echolocation calls. It’s now generally known as the Alcathoe bat (the name ‘Alcathoe’s bat’ is used a lot, but is – so I’m told – incorrect). First reported from Greece, it was later reported from Slovakia, Germany, Poland, Albania, Turkey and, most recently, from two widely separate locations in the UK (Jan et al. 2010). It seems to be a widely distributed but rare species limited to moist deciduous forests with old trees and running water. In reviewing its distribution as of 2007, Niermann et al. (2007) suggested that it might be discovered even further north than Germany: a prediction borne out by its discovery in Yorkshire, England [adjacent M. alcathoe photo © Cyril Schönbächler].
Judging from the results of Mayer et al. (2007), some additional European mouse-eared bat species possibly await recognition. Bats from Austria and Italy – identified for morphological reasons as Natterer’s bat M. nattereri – were significantly different in mtDNA from other Natterer’s bat samples, while Bulgarian bats identified as individuals of the Whiskered bat M. mystacinus carried a distinct mtDNA haplotype relative to ‘true’ M. mystacinus (Mayer et al. 2007). Bulgaria is already home to two mouse-eared bat populations that have sometimes been confused but do seem distinct, namely M. mystacinus bulgaricus and M. aurascens. The latter – sometimes called the Steppe whiskered bat – was named in 1935 as a subspecies of the Whiskered bat. It seems to be the commonest mouse-eared bat on the Balkan Peninsula, being known from Albania, Bulgaria, Greece, Serbia, Kosovo, Macedonia and Montenegro (Benda 2004).
Even this isn’t the end of it, as there are additional bat populations on the Canary Islands and on some of the Greek islands that have proved substantially different in genetics from the other populations conventionally included with them in the same species. In the cladogram below – from Mayer et al. (2007) – the species first recognised thanks to molecular techniques have their names placed within white rectangles, while the new cryptic species discovered in this one study are signified by the black rectangles.
So far, recent studies on European vesper bats have resulted in the proposed existence of more than 15 hitherto overlooked bat species in the region, and continuing studies indicate that even more await recognition. Some of the bats discussed here have also been discovered using more ‘traditional’ means: that is, by the discovery of individuals that look different from their close relatives, and are then judged to warrant specific status. We might regard it as unbelievable and amazing that Europe (of all places) continues to yield such species. On the other hand, the discovery of new tetrapod species isn’t a rare thing (something I’ve tried to emphasis here on Tet Zoo), and maybe we shouldn’t be surprised at all.
Finally, I know that a lot of people are sceptical when it comes to the recognition of cryptic species and sometimes insist that there’s little point in recognising them as distinct, nameable entities. However, this ignores the important facts that (1) while some species might look very much alike, it’s not looks alone that matter, and (2) those cryptic species are frequently relatively old and relatively distinct (genetically at least) relative to their close relatives, frequently being as old and as distinct – if not more distinct – than many traditionally recognised species.
For previous Tet Zoo articles on microbats see…
- Desmodontines: the amazing vampire bats
- Giant extinct vampire bats: bane of the Pleistocene megafauna
- Camazotz and the age of vampires
- Dark origins: the mysterious evolution of blood-feeding in bats
- A new hypothesis on the evolution of blood-feeding: food source duality involving nectarivory. Catchy, no?
- The most terrestrial of bats
- I stroked a pipistrelle
- Red bats
- Big animalivorous microbats
And for more on recently discovered mammals, see…
- The first new European mammal in 100 years? You must be joking
- Monster hunting? Well, no. No.
- Multiple new species of large, living mammal (part I)
- Belated welcome to a ‘new’ clouded leopard… named in 1823
- Tetrapods of 2007 (happy birthday Tet Zoo part II)
- Chinese black rhinos and deinotheres, giant sengis, and yet more new lemurs
- New, obscure, and nearly extinct rodents of South America, and… when fossils come alive
- Giant furry pets of the Incas
- Over 400 new mammal species have been named since 1993
- A new species of modern-day rhinoceros
- A new modern mammal for Madagascar
Refs – –
Ashrafi, S., Bontadina, F., Kiefer, A., Pavlinic, I. & Arlettaz, R. 2010. Multiple morphological characters needed for field identification of cryptic long-eared bat species around the Swiss Alps. Journal of Zoology doi:10.1111/j.1469-7998.2010.00697.x
Barlow, K., Jones, G., & Barratt, E. (1997). Can skull morphology be used to predict ecological relationships between bat species? A test using two cryptic species of pipistrelle Proceedings of the Royal Society B: Biological Sciences, 264 (1388), 1695-1700 DOI: 10.1098/rspb.1997.0235
Benda, P. 2004. First record of Myotis aurascens and second record of Myotis brandtii in Montenegro. Lynx 35, 13-18.
Bogdanowicz, W. 1990. Geographic variation and taxonomy of Daubenton’s bat, Myotis daubentoni, in Europe. Journal of Mammalogy 71, 205-218.
Davidson-Watts, I. & Jones, G. 2005. Differences in foraging behaviour between Pipistrellus pipistrellus (Schreber, 1774) and Pipistrellus pygmaeus (Leach, 1825). Journal of Zoology 268, 55-62.
Jan, C. M. I., Frith, K., Glover, A. M., Butlin, R. K., Scott, C. D., Greenaway, F., Ruedi, M., Frantz, A. C., Dawson, D. A. & Altringham, J. D. 2010. Myotis alcathoe confirmed in the UK from mitochondrial and microsatellite DNA. Acta Chiropterologica 12, 471-483.
Juste, J., Ibáñez, C., Muñoz, J., Trujillo, D., Benda, P., Karatş, A. & Ruedi, M. 2004. Mitochondrial phylogeography of the long-eared bats (Plecotus) in the Mediterranean Palaearctic and Atlantic Islands. Molecular Phylogenetics and Evolution 31, 1114-1126.
Kiefer, A. & Veith, M. 2001. A new species of long-eared bat from Europe (Chiroptera: Vespertilionidae). Myotis 39, 5-16.
Mayer, F. & von Helversen, O. 2001. Cryptic diversity in European bats. Proceedings of the Royal Society of London B 268, 1825-1832.
– ., Dietz, C. & Kiefer, A. 2007. Molecular species identification boosts bat diversity. Frontiers in Zoology 4, 1-4.
Niermann, I., Biedermann, M., Bogdanowicz, W., Brinkmann, R., Le Bris, Y., Ciechanowski, M., Dietz, C., Dietz, I., Estók, P., Helversen, O. V., Le Houédec, A., Paksuz, S., Petrov, B. P., Özkan, B., Piksa, K., Rachwald, A., Roué, S. Y., Sachanowicz, K., Schorcht, W., Tereba, A. & Mayer, F. 2007. Biogeography of the recently described Myotis alcathoe von Helversen and Heller, 2001. Acta Chiropterologica 9, 361-378.
Spitzenberger, F., Piálek, J. & Haring, E. 2001. Systematics of the genus Plecotus (Mammalia, Vespertilionidae) in Austria based on morphometric and molecular investigations. Folia Zoologica 50, 161-172.
– ., Strelkov, P. P., Winkler, H. & Haring, E. 2006. A preliminary revision of the genus Plecotus (Chiroptera, Vespertilionidae) based on genetic and morphological results. Zoologica Scripta 35, 187-230.
Tupinier, Y. 1977. Description d’une Chauve-souris nouvelle: Myotis nathalinae nov. sp. (Chiroptera, Vespertilionidae). Mammalia 41, 327-340.
Tvrtković, N., Pavlinić, I. & Haring, E. 2005. Four species of long-eared bats (Plecotus, Geoffroy, 1818; Mammalia, Vespertilionidae) in Croatia: field identification and distribution. Folia Zoologica 54, 75-88.