Collembola of the genus Protaphorura Absolon, 1901 (Onychiuridae) in the Eastern Palearctic: morphology, distribution, identification key

Abstract Seven new species, Protaphorura jernika sp. n., Protaphorura abscondita sp. n., Protaphorura tuvinica sp. n., Protaphorura vasilinae sp. n., Protaphorura sayanica sp. n., Protaphorura oligopseudocellata sp. n. and Protaphorura nikolai sp. n. from different habitats of the southern Siberia and Far East of Russia, are described. Protaphorura ombrophila (Stach, 1960) is redescribed based on the type specimens. These species differ one from other and from all known species by dorsal and ventral pseudocellar formulae, number of pseudocelli on subcoxae 1 of legs I–III, parapseudocellar formula, chaetotaxy of body, structure of claw, size of postantennal organ and body length. Geographical distribution of all known Protaphorura species of Eastern Palearctic was analysed and an identification key to 50 species was provided.

Etymology. The name of the new species refers to the Latin absconditus (hidden, concealed).
Description. Holotype (female) length 1.8 mm, length of paratypes: 1.4 mm (males). Shape of body typical for the genus: cylindrical with strong AS on distinct papillae (Fig. 10). Colour in alcohol yellowish-white. Granulation distinct, usually slightly coarser on head, Abd. tergum VI and around pso. Usually 9-11 grains around each pso.
Etymology. The name of the new species refers to the Russian "jernik" (= shrub tundra or tundra with dwarf birch).
Etymology. The species is cordially dedicated to Russian oribatologist Dr. Nikolay Ryabinin, who collected the type material of new species in Primorsky Krai of Russia.
Description. Holotype (female) length 2.2 mm, length of paratypes: 2.0-2.3 mm (females). Shape of body typical of the genus: cylindrical with strong AS on distinct pa-pillae ( Fig. 26). Colour in alcohol yellowish-white. Granulation more or less uniform, distinct. Usually 7-10 grains around each pso.
Etymology. The name of the new species refers to the Latin oligo (a few) and pseudocellus (false ocellus) -characteristic structure in Onychiuroidea.
Discussion. Protaphorura oligopseudocellata sp. n. is characterized by the reduced number of pso on body dorsally -32/011/22232. Only four species with 1+1 pso on Th. tergum III is currently known: P. januarii (Weiner, 1977), P. stiriaca (Stach, 1946), P. pseudostyriaca (Loksa, 1964) and P. pseudarmata (Folsom, 1917). The first three species are described from Europe and the last one from North America. Among these species P. oligopseudocellata sp. n. is probably the most similar to P. januarii and P. stiriaca due to the absence of pso on subcoxa 1 of all legs and some similarity of dorsal pso formulae. The new species can be easily distinguished from these species by the number of pso on Abd. terga I-V (22232 in P. oligopseudocellata sp. n., 23232 in P. januarii and 33232 in P. stiriaca), the plurichaetotic chaetotaxy and by the presence of strong lateral denticles on claws and 1+1 pso on head ventrally (lateral denticles and pso absent in P. januarii and P. stiriaca).
Redescription. Lectotype (female) length 1.9 mm, length of paralectotypes: 1.8 mm (male) and 1.8-2.2 mm (females). Shape of body typical of the genus: cylindrical with strong AS on distinct papillae. Colour in alcohol white. Granulation more or less uniform, distinct. Usually 11-13 grains around each pso.
Remarks. Protaphorura ombrophila has been described by Stach (1960) from Afghanistan about 55 years ago, when many important diagnostic characters remained unknown. Latter Yosii (1966), during his research on some Collembola of Afghanistan, India and Ceylon, discovered three females of the species in Afghanistan and wrote: "They (i.e. P. ombrophila) coincide fairly well with the detailed description of Stach. However, the posterior margin of head has 3+3, 3+2 and 2+2 pseudocelli. In other respects no difference is to be found". Parimuchová and Kováč in their recent publication (2016) devoted to the critical analysis of Palearctic species of the genus Protaphorura and assigned this species to the group "species dubia". Here we present first redescription of P. ombrophila based on characters currently used in taxonomy of Protaphorura. See also the discussion in P. tuvinica sp. n. Diagnosis. PAO with 41-48 simple vesicles. Pso formula dorsally 32/022/33343, ventrally 1/000/0000, subcoxae 1 of I-III legs with 1,1,1 pso respectively. Submedial Description. Holotype (male) length 2.7 mm, length of paratypes: 2.7-2.9 mm (females). Other specimens length: 2.6-2.7 mm males and 2.8 mm female. Shape of body typical of the genus: cylindrical with strong AS on distinct papillae (Fig. 37). Colour in alcohol yellowish-white. Granulation more or less uniform, distinct. Usually 7-9 grains around each pso.
Etymology. The name of the new species refers to the Sayan Mountains in Southern Siberia, an area where the type specimens were collected.
Discussion. Protaphorura sayanica sp. n. is probably the most similar to such Asiatic Protaphorura species as P. pjasinae (Martynova, 1976), P. microtica (Dunger, 1978) and P. subarctica (Martynova, 1976) due to the presence of the same number of pso on subcoxae 1 of all legs, ventral and dorsal side of head, Th. terga I-II and Abd. terga I-IV. However, P. sayanica sp. n. may easily be distinguished from these species by the number of pso on Abd. tergum V (3+3 pso in the new species and 2+2 pso all other species presented above) and presence of pair of lateral denticles on claw (absent in other four species). . Paratypes: 10 males, 3 females and 7 juveniles, same data as holotype (SNHM -6 paratypes: 5 males and 1 female, ISEA -4 paratypes: 3 males and 1 female, MSPU -4paratypes: 3 males and 1 female, and 7 juveniles).
Etymology. The name of the new species refers to the Tuva Republic (Russian Federation), the place where the type specimens were collected.
The new species has the pseudocellar formula the same as in kopetdagi (32/022/33332) when the other posses the different number of pseudocelli. The males of P. kopetdagi, P. salsa, P. bakhchisaraica and P. ajudagi are armed with the male ventral organ whereas the new species and P. ombrophila have males devoided of the organ. P. tuvinica differs also from the latter species by the number of pso on Abd. terga IV-V (3,2 in the new species and 4,2 in P. ombrophila).
Description. Holotype (female) length 1.5 mm, length of paratypes: 1.4-1.7 mm (females). Shape of body typical of the genus: cylindrical with strong AS on distinct papillae (Fig. 51). Colour in alcohol yellowish-white. Granulation more or less uniform, distinct. Usually 10-12 grains around each pso.
Etymology. The species is cordially dedicated to Vasilina, a granddaughter of Dr. Sophya Stebaeva.

Key to Protaphorura species of the Eastern Palearctic
For the species with high variability in the pseudocellar formula we used in the key the most common type.