Uralaphorura yanensis Babenko, 2009, sp. nov.

Uralaphorura yanensis sp. nov.

Figs 9–13

Description. Colour white. Size up to 1.55 mm. Body rather broad, Abd.VI small. Granulation fine and uniform, without differentiated fields of coarser granules.

Microsensillum on Ant.IV set clearly above second proximal whorl of setae (Fig. 10), subapical organite present. Ant.III organ with 4 papillae, two sensory rods, two small almost rod-like granulated clubs, 5 guard setae, and lateral microsensillum (Fig. 10, 10 a). Ant.I–II with 9 and 16–18 setae.

PAO with 11–13 simple vesicles, bilobed in central part of the organ (Fig. 9). Labrum as usual with 4 prelabral and 9 labral setae. Labium with thick terminal seta on papilla A, 7 long guards and 6 proximal setae. Basal fields of labium with 4+6 setae. Maxillary palp simple with two sublobal hairs.

Formulas of pseudocelli: dorsal 32/02(3)2(3)/33232, ventral 0/000/0000. The presence of all three dorsal pso on Th.II–III not frequent: among available specimens 1 male and 2 females have 2+2 pso on both Th.II–III, 1 female (immature) – 2+2 and 3+2 pso, and 1 female (holotype) – 3+2 and 2+3 pseudocelli on Th.II–III, correspondingly. All studied juveniles lack pso2 on both thoracic terga. Parapseudocelli (psx) as follows: 2/000/2212, on head one psx in median position, other psx lateral. Each subcoxa with one pso and one psx. One psx present also on inner side of each femur and two psx (outer and inner) on Ant.III.

Localization of pso and psx as on Figs 12–13.

Dorsal chaetotaxy slightly plurichaetotic and not fully symmetrical. Differentiation of setae less pronounced than in other species of the genus, macrosetae more or less distinct, but rather short even on abdominal tip. Most setae blunt. Th.II–III with lateral microsensilla. Immature specimens always with d0 on head present, in adults this seta often absent or doubled. Abd.IV–V with or without unpaired median setae, Abd.VI always without dorsal axial setae (Fig. 12). Thoracic sterna without setae along linea ventralis, ventral chaetotaxy of abdomen as on Fig. 13. Furcal remnant as finely granulated area with a line of 4 posterior setulae. Male organ absent. Ventral tube with ca. 10+10 distal and 1+1 proximal setae.

Each subcoxa with 4(5) setae. Tibiotarsi with about 20 setae, number of setae in proximal whorl slightly variable (all four T-setae present, 7 setae in A-whorl, 7(6) in B-whorl, 1–3 setae in C-whorl, setae M and Y) (Fig. 11). Setae A1 on all tibiotarsi, B4–5 on Ti.I–II and B5 on Ti.III longer than others but not clavate. Unguis with clear tooth in upper half of inner edge, lateral teeth absent, unguiculus without basal visible lamella, about as long as inner edge of unguis. Anal spines present, set on low papillae.

Type material. Holotype, female, Russia, Yakutia (Sakha Republic), mouth of Yana River, Shirokostan Peninsula, nearby Lyadyanoe lake (72°25'N, 141°00'E), herbaceous meadow on south facing slope of a hill, 5.viii.1994, A. Babenko leg., in MSPU; paratypes: 2 females, male, and 19 juveniles, same data as holotype, in MSPU.

Affinities. The new species is very similar to U. schilovi having many features in common (see Table 1) but can easily be distinguished because of the pointed tibiotarsal setae and the absence of unpaired axial setae on the tergum of Abd.VI. In addition, mature specimens of U. schilovi always have 3+3 pso on Th.II–III, whereas the absence of pso2 on these terga is a frequent character of U. yanensis sp. nov.

Etymology. Named after Yana River.

Distribution. Apart from the type locality (north-eastern Yakutia) a few immature specimens which probably belong to U. yanensis sp. nov. were recorded on the Taimyr Peninsula as U. cf. schilovi by Babenko (2003) and Babenko & Fjellberg (2006).

Character U. schilovi U. tunguzica U. varicellata U. yanensis known distribution Northern Europe: Siberia: Yenisei River Siberia: Eastern Yakutia Siberia: North-Eastern

Norway, Urals, Novaya basin Yakutia, Taimyr Zemlya Archipelago Peninsula (?)

Remarks. * In the original description of U. tunguzica Babenko, 2007 lateral psx on head and median one on Abd.2 were overlooked. ** Only psx in usual (lower lateral) position are taken into account.