Endonura Cassagnau in Iran, with a key to species of the genus (Collembola, Neanuridae, Neanurinae)

Abstract Three new species of Endonura are described from Iran. Endonura dichaeta sp. n. can be recognized by an ogival labrum, head without chaetae O and E, chaeta D connected with tubercle Cl, tubercle Dl with five chaetae on head, absence of tubercles Di on thorax I and tubercle (Di+Di) of thorax V with 2+2 chaetae. Endonura ceratolabralis sp. n. is characterized by large body size, reduction of labral chaetotaxy, ogival labrum, head without chaeta O and fusion of tubercles Di and De on first thoracic segment. Endonura persica sp. n. is distinguished from its congeners by a nonogival labrum, absence of chaeta O, tubercles Dl and (L+So) with five and eight chaetae respectively and claw with inner tooth. The key to all species of the genus is given.


Introduction
Endonura was established by Cassagnau (1979) as one of four subgenera within the genus Neanura MacGilliwray, 1893. Later, Deharveng (1982) raised it to the generic level. At present, Endonura is one of the largest (37 valid species) and most accurately studied genera within the subfamily Neanurinae (Dallai 1983, Deharveng 1979, 1982, Fanciulli and Dallai 2008, Pomorski and Skarżyński 2000, Pozo and Simón 1982, Smolis and Kaprus' 2003, 2009, Smolis 2006, Smolis et al. 2007, 2011. It is mostly a Palaearctic genus and only one species, E. reticulata (Axelson, 1905), is known from the Nearctic (Alaska, Smolis et al. 2011). According to a recent definition (Smolis 2008), Endonura is characterized by the following characters: 0-2 ocelli, reduced mouth parts with a thin mandible and a styliform maxilla, separate tubercles Di and De on the head, the non-cross-type of chaetotaxy on the head and three or two tubercles on abdomen V. The highest species diversity is observed in Europe (32 from among the 37 known species). However, this may be a false picture because many areas of the Palaearctic have been poorly studied by collembologists. Undoubtedly, one of such regions is Central Asia, but in this case the situation is rapidly and positively changing (Arbea and Kahrarian 2015, Kahrarian 2014, Mayvan et al. 2015, Shayanmehr et al. 2013, Smolis et al. 2012). In the present paper, three new non-European Endonura from the western part of Iran are described. An updated key to all species of the genus is included.

Materials and methods
The specimens were cleared in Nesbitt's fluid, subsequently mounted on slides in Swan's medium and observed using a phase contrast microscope Nikon E600. Photographs were made using a camera Nikon D5100 mounted on a microscope mentioned above. Photographs were stacked using Helicon Focus 6.  Description. Habitus typical of the genus. Body length (without antennae): 0.75-1.55 mm (holotype 1.30 mm). Colour of the body white. 2+2 medium unpigmented eyes (Fig. 1).
Diagnosis. Habitus typical of the genus Endonura. Dorsal tubercles present and well developed. 2+2 eyes darkly pigmented. Buccal cone long. Head with chaetae A, B, C, D, E, F and G. Chaeta O absent. Tubercles Cl and Af separate. Tubercles Dl and (L+So) on head with six and nine chaetae respectively. Tuberles Di and De on th. I fused. Tubercles De on th. II and III with three and four chaetae respectively. Tubercles L on abd. III and IV with three and 6-7 chaetae respectively. Abd. IV and V with eight and three tubercles respectively. Claw without inner tooth. Tibiotarsi with chaetae B4 and B5 short.
Head. Buccal cone very long. Labrum ogival, with ventral sclerifications as in Fig. 6. Labrum chaetotaxy 0/2, 2. Labium with four basal, three distal and four lateral chaetae, papillae x absent. Maxilla styliform, mandible thin with two basal and two apical teeth. Chaetotaxy of antennae as in Table 2c. Apical vesicle distinct, trilobed. S-chaetae of ant.IV of medium length and moderately thickened. Chaetotaxy of head as in Table 2a Thorax, abdomen, legs. Body s-chaetae thin and smooth, shorter than nearby macrochaetae (Figs 7-9). Chaetotaxy of th. and abd. as in Table 2d and in Figs 7-9. Tubercles Di on th.I differentiated and fused with De (Fig. 7). Dorsal side of th. and abd. without free chaetae De. The line of chaetae De1-chaeta s perpendicular to the dorsomedian line on abd I-III. Furca rudimentary with two or without microchaetae. Tubercles Di on abd. V fused, with chaetae Di2 and Di3 as Mc (Fig. 9). Chaetae L' and Vl on abd. V present. No cryptopygy. Chaetotaxy of legs as in Table 2d. Remarks. Because of the very characteristic long and pointed labrum, E. ceratolabralis sp. n. seems to be most similar to E. cretensis (Ellis, 1976) (Crete) and E. gracilirostris Smolis et al. 2007 (Crimea). Nevertheless, the new species can be easily distinguished from these two taxa by the following combination of characters: maximum length of the body without antennae (ceratolabralis sp. n. 2.55 mm; gracilirostris  (L+So) on head with five and eight chaetae respectively. Tubercles De on th. II and III with three and four chaetae respectively. Tubercles L on abd. III and IV with four and 6-7 chaetae respectively. Abd. IV and V with eight and three tubercles respectively. Claw with inner tooth. Tibiotarsi with chaetae B4 and B5 long.
Elementary tubercle BE absent. Chaeta A shorter than B. Thorax, abdomen, legs. Body s-chaetae fine and smooth, distinctly shorter than nearby macrochaetae (Fig. 12). Chaetotaxy of th. and abd. as in Table 3d and in Figs 10, 12. Tubercles Di on th.I differentiated or not. Chaetae De2 on th. II-III and De3 on th. III free. Chaetae De3 on abd. I-III free (Fig. 12). The line of chaetae De1chaeta s parallel to the dorsomedian line on abd. I-III. Furca rudimentary without microchaetae. Tubercles Di on abd. V fused, with chaetae Di2 as Mcc and Di3 as mi (Fig. 12). Chaetae Vl on abd. V present. Cryptopygy slightly developed. Chaetotaxy of legs as in Table 3d. Tibiotarsi with rather long chaetae B4 and B5. Claw with inner tooth (Fig. 13).
Remarks. In general appearance and presence of inner tooth on claw, characters rarely observed within the genus, E. persica sp. n. strongly resembles to E. dentifera Smolis et al. 2007 (described from Crimea). However, the new species can be reliably separated from Crimean species with the following characters: number of chaetae Dl on head (persica sp. n. five, dentifera six), number of chaetae (L+So) on head (persica sp. n. eight, dentifera ten), presence/absence of tubercles Di on the first thoracic segment (persica sp. n. present, dentifera absent) and number of chaetae L of abd. IV (persica sp. n. 6-7 chaetae, dentifera 8-9).

Key to the genus Endonura
In 1982, Deharveng, in his PhD thesis, elevated Endonura to the generic level and prepared a key to the genus that comprised 23 species. Nowadays, including the taxa described herein, the genus contains 40 members and is the second largest of the tribe Neanurini, after Deutonura Cassagnau, 1979. Moreover, after the publication of Deharveng's paper (date), a few species were redescribed and one taxon was synonymised  (Smolis and Kaprus' 2003, Smolis 2008, Smolis et al. 2007, 2011. Considering these facts, the preparation of an updated key to all species of the genus seemed to be highly recommended.  Tubercles Di on th. I present ...E. arbasensis Deharveng, 1979

Discussion
Considering the data presented here and those obtained from the literature (Mayvan et al. 2015, Shayanmehr et al. 2013, Smolis et al. 2012, Neanurinae fauna of Iran comprises ten species and seven genera: Bilobella aurantiaca (Caroli, 1912), Cryptonura persica Smolis et al., 2012, C. maxima Smolis et al., 2012, Deutonura decolorata (Gama & Gisin, 1964) (Gisin 1964), Endonura ceratolabralis sp. n., E. dichaeta sp. n., E. persica, sp. n., Neanura muscorum (Templeton, 1835), Persanura hyrcanica Mayvan et al. 2015, Thaumanura echinata (Kos, 1940). It should be noted, however, that until now only the western part of Iran has been roughly studied. Although future research may change the present picture of the subfamily diversity in the studied country and region, some preliminary conclusions can be drawn. The first is related to the higher systematic pattern and composition of Neanurinae of Iran. This fauna consists almost exclusively of members of the tribe Neanurini, the most diverse and dominant among Neanurinae in the western Palaearctic. To date, none of the Lobellini and Paranurini genera have been found in Iran, although they are numerous and widely distributed in south, south-east and east Asia. The second conclusion seems to be more expected, Endonura species from Iran resemble those known from south-east Europe. It suggests their close affinity and the historical connection between these faunas. The third conclusion sheds light on the distribution and the history of this genus. Most Endonura species were recorded from Mediterranean and temperate zones of Europe, where they live predominantly in forests. It is worth saying that the greatest diversity of the genus through the continent is more or less correlated to the areas of land that have never been subjected to glaciations. Till now, the occurrence of only a few species is documented outside Europe, especially in the Middle East Kaprus 2003, 2009;Smolis et al. 2011). The recent and present discoveries of Endonura species in Kyrgyzstan (Smolis et al. 2011) and Iran significantly expand the list of species and also our knowledge on the genus. Undoubtedly, diverse forest habitats of the coastal and montane regions of Iran and adjacent countries hide a rich fauna of Neanurinae. We therefore hope that a more comprehensive study in the future will allow us to present a better picture of the distribution of Endonura in Iran and the near East.