The genera Albanura Deharveng, 1982 and Persanura Mayvan et al., 2015 are no longer monotypic: description of new species from the Caucasus (Collembola, Neanuridae, Neanurinae, Neanurini)

Abstract Two new species from the Caucasus belonging to the genera Albanura and Persanura are described and illustrated in detail. Albanura secunda sp. n. is distinctive because of the presence of chaetae E on the head as well as three ordinary chaetae on tubercles De of thorax III and abdomen I–III. Additionally, the species can be recognized by the absence of chaeta O on the head and presence of 3+3 chaetae Di on abdomen V. The most important characters that can be used to distinguish Persanura lencarana sp. n. are the labral formula, an increased number of chaetae De on thorax II and III, and the number of chaetae Di on the thorax and abdomen V. Comments on the status of the genera and the affinities of the Caucasian fauna of Neanurinae are also given.


Introduction
Creating and establishing new genera, especially monotypic ones, may be very problematic and complicated for taxonomists. Very often such decisions are questioned by other specialists, and authors who decide on such choices are often labelled as 'splitters'. Interestingly, the term 'splitter' was used for the first time by one of the most famous biologists, Charles Robert Darwin. Among Neanurini, one of the six tribes within the subfamily Neanurinae (Cassagnau, 1989), there are both large and "megadiverse" genera, e.g., Deutonura Cassagnau, 1979 andEndonura Cassagnau, 1979 comprising 57 and 51 valid species, respectively (Cassagnau 1979, Smolis and Kaprus' 2009, Porco et al. 2010, Deharveng et al. 2015, Smolis and Kuznetsova 2016, Smolis et al. 2017, and several monotypic ones, e.g. Albanura Deharveng, 1982, Cansilianura Dallai & Fanciulli, 1983, Edoughnura Deharveng et al., 2007, Xylanura Smolis, 2011, or Persanura Mayvan et al., 2015(Deharveng 1982, Dallai and Fanciulli 1983, Deharveng et al. 2007, Smolis 2011, Mayvan et al. 2015. The examination of rich Neanurinae materials from the Caucasus collected during primarily ecological research has revealed two unknown species that should be classified within the so far monotypic genera Albanura and Persanura. The genus Albanura was created by Deharveng (1982) for Neanura (Deutonura) nana Cassagnau & Péja, 1979, from Albania (Cassagnau and Péja 1979), whilst the genus Persanura was established recently by Mayvan et al. (2015) for the species Persanura hyrcanica Mayvan et al., 2015 from Iran. Illustrated descriptions of the new species with remarks on the status of both corresponding genera and the possible origin of the Neanurinae fauna of the region are provided herewith.

Materials and methods
The specimens were cleared in Nesbitt's fluid, subsequently mounted on slides in Phoera liquid (200 g of chloral hydrate, 30 g of arabic gum and 20 g of glycerol dissolved and mixed into 50 g of distilled water) and studied using a Nikon Eclipse E600 phase contrast microscope. Figures were drawn with camera lucida and prepared for publication using Adobe Photoshop CS3.
Etymology. The name secunda refers to the fact that the new species is the second member of the genus.
Diagnosis. Habitus similar to that of Albanura nana. Dorsal tubercles present and well developed. Buccal cone long, labrum ogival. Head with chaetae A, B, C, D and E. Chaeta O absent. Tubercles Dl and (L+So) on head with six and nine chaetae respectively. Tubercles De on Th. II and III with three and four chaetae respectively. Tubercles De on Abd. I-III with four chaetae. Tubercles L on Abd. III and IV with four and seven chaetae respectively. Abd. IV and V with seven and three tubercles respectively. Abd. V with 3+3 chaetae Di.
Description. General. Body length (without antennae): 0.8 mm (holotype), 0.9 mm (paratype). Colour of the body white. 2+2 rather large black eyes, in a typical arrangement for the genus (one anterior and one posterior, Fig. 1).
Dorsal chaetotaxy and tubercles. Chaetotaxy of head as in Figs 1, 2 and Table 1. Chaetotaxy of thorax and abdomen as in Figs 3, 4 and Table 3. Th. III with chaetae De3 free (Fig. 1). On Abd. I-III, the line of chaetae De1-chaeta s is not perpendicular to the dorsomedian line. No cryptopygy, Abd. VI well visible from above (Fig. 9).
Legs. Chaetotaxy of legs as in Table 3. Claw without internal tooth. On tibiotarsus, chaeta M present and chaetae B4 and B5 relatively short and pointed.
Remarks. Albanura secunda sp. n is easily distinguished from A. nana Cassagnau & Péja, 1979, the only other known species in the genus, by its dorsal chaetotaxy: presence/absence of chaeta O on the head (absent in secunda; present in nana), presence/    (Fig. 14).
Legs. Chaetotaxy of legs as in Table 6. Claw without internal tooth. On tibiotarsus, chaeta M present and chaetae B4 and B5 relatively short and pointed, chaeta A6 similarly in length to chaeta B4 (Fig. 21).
Remarks. Persanura lencarana sp. n. most visibly differs from P. hyrcanica in the presence of a complete chaetotaxy in the central area of the head (reduced chaetae C, E and O absent in hyrcanica), the presence of two chaetae Di on Th. I (one chaeta in hyrcanica), the presence of three chaetae Di on Th. II-III (two chaetae in hyrcanica), the presence of four and five ordinary chaetae De on Th. II and III, respectively (two chaetae in hyrcanica), the presence of three ordinary chaetae De on Abd. I-III (two chaetae in hyrcanica), and the presence of three chaetae Di on the penultimate abdominal segment (two chaetae in hyrcanica). In addition, they differ in the number of labral chaetae (4/2, 4 in lencarana; 0/0, 4 in hyrcanica), the presence/absence of chaetae Dl3 on the head (present in lencarana; absent in hyrcanica), the number of chaetae L of Abd. IV (8 in lencarana; 3-5 in hyrcanica), and the presence/absence of microchaetae on furca rudimentary (present in lencarana; absent in hyrcanica).

Discussion
The discovery of new species, e.g. Albanura secunda sp. n. and Persanura lencarana sp. n. described herein, in so far monotypic genera undoubtedly enriches and extends their characteristics providing new facts about their morphological differentiation. In some cases, nevertheless, they may reduce the number of distinguishing characters available for the genera. For example, the number and arrangement of labral chaetae in P. lencarana sp. n. is typical within the tribe and significantly different from the number described in the type species, P. hyrcanica Mayvan et al., 2015, where it was used as a one of the important generic feature of Persanura Mayvan et al., 2015(Mayvan et al. 2015. On the other hand, strong mandibles, which were not used by the authors of this genus for comparison with other morphologically similar genera, like Kalanura Smolis, 2007, Neanura MacGillivray, 1893, and Xylanura Smolis, 2011(MacGillivray 1893, Smolis 2007, 2011, appear to be a good and distinctive element of its characteristics. Likewise, A. secunda sp. n. is characterized by 3 + 3 chaetae Di on Abd. V as opposed to 2 + 2 chaetae in the type species of Albanura Deharveng, 1982. Thus, this feature cannot be further used as unique and diagnostic. Besides, new data on the morphological characteristics of originally monobasic genera, provide additional information that may support their recognition, such as geographic location. Interestingly, in the case of Albanura, a taxon morphologically closely related to Deutonura Cassagnau, 1979, but geographically separated, the author of the genus (Deharveng 1982) recognized the geographical criterion as important for its establishment. In the light of the discovery of A. secunda sp. n., the author's decision seems to be justified as the distributional pattern of the genus is completely different from that which is known in Deutonura. Interestingly none species of Deutonura is known from the Caucasus where other genera of Neanurini, more or less widely distributed in the Western Palearctic, were observed e.g. Endonura, Persanura and Caucasanura Kuznetsova & Potapov, 1988. This last genus up to date includes two species, Caucasanura stebayevae Kuznetsova & Potapov, 1988, known from the Caucasus (Kuznetsova and Potapov 1988) and Caucasanura besucheti Deharveng, 1989, from north-eastern Turkey (Deharveng 1989).
In addition to supporting taxonomic decisions such as the establishing of monobasic genera, the species described in this work shed light on the origin and composition of the Neanurinae fauna of the Caucasus. The fauna of this subfamily in the region, despite our still poor knowledge, seems to contain elements belonging to the eastern part of Mediterranean Sea and Asia Minor as well as to the mountains in Iran. This assumption is consistent with recent observations on the genus Endonura from the Caucasus, where some of its representatives closely resemble both Mediterranean and Iranian species (Smolis et al. 2016a, b). Undoubtedly, further studies are necessary to understand the diversity and history of the subfamily in this extremely rich natural region, one of the two biodiversity hotspots located in the Western Palaearctic (Myers et al. 2000).