On a new Dictyna species (Araneae, Dictynidae) from the northern Palaearctic confused with the East Siberian D. schmidti Kulczyński, 1926

Abstract A new species, Dictyna palmgreni sp. n., is described from Finland and Russia on the basis of both sexes. Most of the earlier records of Dictyna schmidti Kulczyński, 1926 from the northern Palaearctic refer to this new species. Dictyna shilenkovi Danilov, 2000, syn. n. from Cisbaikalia is synonymised with Dictyna schmidti. The general appearances and copulatory organs of Dictyna palmgreni sp. n., Dictyna schmidti and Dictyna major Menge, 1869 are illustrated. The distribution of Dictyna palmgreni sp. n. andDictyna schmidti is clarified. An unknown sac-like structure of the spermathecae of Dictyninae is briefly discussed.


Introduction
Dictynidae is a globally distributed medium-sized family with 566 chiefly cribellate species belonging to 50 genera (Platnick 2011). The largest dictynid genus is Dictyna Sundevall, 1833. It encompasses 123 species distributed mainly in the Holarctic Re-gion (Platnick 2011). Although Dictyna is a fairly large genus and its representatives are rather common, this genus has never been revised on a wide scale. The only detailed revision made for the Nearctic fauna is that by Chamberlin and Gertsch (1958).
The family, and the genus Dictyna particularly, is relatively well studied in northern Europe and Asia. Nevertheless, several species occurring in Siberia and northern Europe remain inadequately studied and are known from the original descriptions or from one sex only. The Siberian Dictynidae have been treated by Kulczyński (1908Kulczyński ( , 1916Kulczyński ( , 1926, Marusik (1988), Danilov (1994Danilov ( , 2000 and Marusik and Koponen (1998).
The species Dictyna schmidti was described from Kamchatka by Kulczyński (1926) on the basis of a single male. Later this species was redescribed on the basis of Finnish specimens (Lehtinen 1967). Reasoning from Lehtinen's illustrations, this species was reported from other localities in Finland and adjacent Russia (Palmgren 1977) and Sweden (Pettersson 1996, Almquist 2006. D. schmidti was also reported from several localities in the Urals (see references in Esyunin and Efimik 1996) and Siberia (see Mikhailov 1997, Danilov 2000. While studying spiders of Siberia and Finland we have found specimens that match Lehtinen's (1967) and Palmgren's (1977) illustrations of D. schmidti. Yet, we have found a few specimens from eastern Siberia that clearly differ from D. schmidti sensu Lehtinen (1967) but well match Kulczyński's description. A comparison of these specimens led us to the conclusion that the widespread species (from Fennoscandia to eastern Siberia) known earlier as D. schmidti in fact belongs to a new species, the description of which is the main goal of this paper.

Material and methods
Specimens were photographed using either a JEOL JSM-5200 scanning electron microscope or an Olympus E-520 camera attached to an Olympus SZX16 stereomicroscope at the Zoological Museum, University of Turku. Drawings were made either by using a grid method with a MBS-9 stereomicroscope or a Leitz stereomicroscope with a camera lucida. Macerated epigynes were temporarily coloured with Chlorazol Black to make some parts more visible. Photographs were taken with specimens in dishes with alcohol and paraffin on the bottom. Holes of different sizes were made in the paraffin to keep the specimens in the appropriate position. The epigynes were macerated either with KOH solution or lactic acid. All measurements are in mm.
Acronyms for depositories: Zoological Museum, University of Turku, Finland (ZMT); Zoological Museum, University of Helsinki, Finland (ZMH); Zoological Museum of the Moscow State University, Russia (ZMMU); Swedish Museum of Natural History, Stockholm, Sweden (NHRS); Perm State University, Russia (PSU); Institute for Biological Problems of the North, Magadan, Russia (IBPN); Institute for Systematic and Ecology of Animals, Novosibirsk, Russia (ISEA); private collection of the second author, Vasa, Finland (NRF).
Distribution. The new species is known across almost the entire northern Palaearctic: from Fennoscandia to Magadan, north to 68° in Finland, and southward to about 53° in Krasnoyarsk Province of Russia. To date, there have apparently been no documented adult specimens from Sweden (L. Jonsson & R. Pettersson pers. comm.), which are needed for the confirmation of its occurrence there.
Distribution. This species is known from East Siberia only (Fig 40): from Transbaikalia, northward to Zhigansk, southward to Ulan-Ude (Buryatia) and Bureinski Reserve (Khabarovsk Province) and eastward to Kamchatka. Natural history. One specimen was collected by sweeping grasses on a north exposed slope in the Upper Kolyma. One male near Magadan was found under stones. The type specimens of D. shilenkovi were mainly collected from mixed forests (Danilov 2000).  Carmacks, 135º55'W 62º04'N, steppe slope and surroundings, 18.07.1993 (Yu.M.Marusik).
Comments. It has not been possible to trace the Finnish specimens used for making the figures of D. schmidti in Almquist (2006). The illustrations are probably based on misidentified specimens and seem to refer to D. major.
Description. Thoroughly described by Wiehle (1953), Chamberlin & Gertsch (1958) and Almquist (2006). Here we provide only comparative figures of the copulatory organs in order to demonstrate differences between it and the similar-looking D. palmgreni sp. n. and D. schmidti.
Distribution. The species has a circum-Holarctic range and is known across the Palaearctic and Nearctic Regions.
Natural history. This species has different habitat preferences in Siberia and in Finland. In Magadan Area, it is the most common dictynid species, occurring in vari-ous habitats within the forest belt and is most numerous on Ledum shrubs. In Finland, D. major is rare, has a scattered distribution and occurs exclusively on dune shores.

Relationships
Studying the relationships between Dictyna and the related Emblyna Chamberlin, 1948 faces certain difficulties. Both genera are species diverse, especially in the Nearc-  tic, and their proper revisions in the Holarctic are lacking. Besides, data on the internal structure of the epigyne of the majority of Nearctic species is also lacking. Although males of the three species D. major, D. palmgreni sp. n. and D. schmidti have similar palps, it is not clear whether they are related or not. The epigynes of these species are rather different. The copulatory openings of D. major and D. palmgreni sp. n. are similar, but those of D. palmgreni sp. n. have a unique digitiform process of receptaculum which is absent in other Dictyna species known to us. The epigyne of D. schmidti differs significantly from both D. major and D. palmgreni sp. n. The male palp of D. schmidti and D. szaboi Chyzer, 1891 1891 (cf. Gajdos and Pekár 1999: figs. 1-4) is also rather similar, both having a very long 3-dimensional conductor and a small tibial dorsal process. The vulva of D. szaboi has never been illustrated.

Notes on the structure of the internal part of epigyne in Dictyninae
While studying the epigynes of D. palmgreni sp. n., D. major and some other Dictyna and Ajmonia species we have found large transparent sac-like structures (cf. Figs. 32-35, 37, 39;Figs. 5, 21 in Marusik and Koponen 1998;Fig. 2 in Marusik et al. 2006;Fig. 1i in Marusik & Esyunin 2010). Other authors have never reported on such structures. When we had prepared a specimen for making SEM photographs and transferred it from alcohol to a filter paper for drying up, the sac-like structure resembled a plastic bag, which immediately collapsed as soon as the filter paper was touched (cf. Fig. 39). Considering the very small size of the Dictyna receptacula, it seems that the sac-like structure serves as an additional unpaired receptaculum. We do not know any similar structures in other families belonging to the RTA-clade. Somewhat similar, unpaired transparent receptacula are known in Dysderidae, Oonopidae and the related haplogyne families (Figs 830-835 in Forster and Platnick 1985), but these are situated below the epigastric furrow and behind the unpaired "receptaculum". In Dictyninae, the sac-like structure is situated between the integument and the paired receptacula.