Folsomia uniparis Potapov & Gulgenova, 2013, sp. nov.

Folsomia uniparis sp. nov.

Figs 31, 33

Type material. Holotype: female. Russia (East Siberia), Buryat Republic, Valley of Uda River, near Khorinsk (ca 150 km N Ulan-Ude), dry pine wood with sparse vegetation covering, flotation of sand, 16.viii.2008 and 3.viii.2009, 3 paratypes from the same locality, leg. A. Gulgenova & M. Potapov. Holotype and 3 paratypes in MSPU.

Other material. Buryat Republic, Dzerginsky Nature Reserve, vicinities of station '81 km' (upper flow of Barguzin River), 1058 m alt., N 55.35563 E 111.48312, high sandy river bank with sparse vegetation, flotation of sand, 10.ix.2012. leg. A. Gulgenova & M. Potapov;

Vitim Highland, Eravna Basin, steppe with Kobresia, Artemisia, and Festuca valesiaca on chernozem soil, near Komsomol’skoe (160 km NE Ulan-Ude), ca. 950 m alt., 27.ix.2009, leg. A. Gulgenova.

Irkutsk Area, west shore of Baikal Lake, nearby Bol'shoye Goloustnoye, taiga forest, viii.1990, leg. M.Kalinin.

Description. Body size about 0.4 mm. Body without pigmentation, slender (Fig. 31). Cuticle with weak hexagonal primary granulation ("smooth"). Ocelli lacking. PAO narrowly elliptical, not constricted, 0.9–1.2 as long as width of Ant I and 1.7–2.2 as long as inner unguis length. Maxillary outer lobe with 4 sublobal hairs, maxillary palp simple. Labral formula as 3/5,5,4. Labium with 5 papillae (А–Е), guard chaetae e7 absent, 3 proximal and 4 basomedian chaetae. Ventral side of a head with 4+4 chaetae. Ant.I with 2 ventral sensilla (s) and 2 small basal microsensilla (bms), dorsal and ventral, the former set together with long chaeta-form microsensillum, Ant.II with 3 bms and 1 latero-distal s, Ant.III without bms and with 5 distal s (including 1 lateral), without additional sensilla. Sensilla on Ant.4 weakly differentiated. Organite small.

Sensillary formula as 4,3/2,2,2,3,5 (s), 1,0/1,0,0 (ms) (Fig. 31). Tergal sensilla as long as common chaetae and hardly distinguishable. Medial sensilla on Th.II–Abd.III situated in mid-tergal position, on Abd.I–III between Mac1 and Mac2. Abd.V with 5 sensilla arranged with 3 dorsal ones (al, accp1, accp2), long and slender and 1 lateral middle-sized sensilla clearly thicker than others and 1 ventral short and thin (as in Fig. 24). Macrochaetae smooth and short, 1,1/3,3,3 in number, medial ones on Abd.V 1,6–1,8 times shorter than dens and 1.4–1.9 times longer than mucro. 7 foil chaetae at the tip of abdomen. Axial chaetotaxy as 7–8,5/3–4,3–4,4 (only one specimen was studied). Thorax without ventral chaetae.

Unguis of normal shape, without lateral and inner teeth. Empodial appendage about half as long as unguis (0.5–0.7). Tibiotarsi without additional chaetae on Leg I and II (21 chaetae), and with few ones on Leg III. Tibiotarsal tenent chaetae pointed. VT with 4+4(5) laterodistal and 5 posterior chaetae, anteriorly without chaetae. Tenaculum with 4+4 teeth and 1 chaeta. Anterior furcal subcoxae with 4–5, posterior one with 3 chaetae. Anterior side of manubrium with 1+1 chaetae (Fig. 33). Posterior side of manubrium with 4+4 laterobasal, 2 apical chaetae (ap), 2+2 chaetae in distal transversal row (M1, L1), and 3+ 3 in central part. One pair of lateral chaetae presnt or absent (varies). Dens with 8 anterior chaetae arranged as 1,1,1,2,3. Posterior side of dens slightly crenulated at the middle and with 2 normal chaetae at base, one rudimentary subapical chaeta usually present (Fig. 33). Mucro bidentate. Ratio of manubrium:dens:mucro =3.1–4.3:2.9–3.2:1.

Discussion. The species belongs to ‘ heterocellata’ group because of the simple maxillary palp. The new species resembles F. h r ab e i Rusek, 1984 (Czechia). Both species share a small body size, blindness, reduced chaetotaxy of posterior side of dens, 3 prelabral chaetae. F. h r a b e i shows different sensillar chaetotaxy: ms on Abd.I absent (present in F. uniparis sp. nov.), sensilla are in p-row on Abd.I (vs. mid-tergal position) and sensilla of "dorsal triplet" of Abd.V are flame-shaped (vs. hair-form). The similarities with F. biparis sp. nov. and F. vitimica sp. nov. are given in the discussions to these species.

Distribution and ecology. Scattered records in Buryatia (Fig. 1: loc. 1, 2, 8, 13). The specis prefers dry and sandy sites.

Etymology With one pair of chaetae on anterior side of manubrium.