Sensillonychiurus vitimicus, Babenko, Anatoly B., Chimitova, Ayuna B. & Stebaeva, Sophya K., 2011

Babenko, Anatoly B., Chimitova, Ayuna B. & Stebaeva, Sophya K., 2011, New Palaearctic species of the tribe Thalassaphorurini Pomorski, 1998 (Collembola, Onychiuridae), ZooKeys 126, pp. 1-38 : 14-15

Sensillonychiurus vitimicus sp. n. Figs 3236

Material.

Holotype ♂, Russia, Siberia, Buryatia, Vitim Plateau, vicinity of Telemba [52°44'N, 113°16'E], larch forest with Betula fruticosa , 23.viii.2009, leg. A. Chimitova (MSPU).

Paratypes 7 ♀ and 3 ♂, same data as holotype; 1♀ same region but … larch forest with rich herbaceous cover, 04.x.2009, leg. A. Chimitova (MSPU).

Description.

Colour white. Size 0.58-0.68 mm (females), 0.50-0.58 (males). Body slender and elongated. Antennae about as long as head, antennal area not clearly demarcated. Ant.4 with 2 distinct thickened sensilla, a subapical organite and a basal microsensillum present, the latter set well above proximal row of setae (Fig. 34). Ant.3 organ consisting of 5 papillae, 2 sensory rods, 2 smooth sensory clubs, 4 guard setae, and a lateral microsensillum (Fig. 34). Ant.1 and 2 with 8 and (12)13 setae, respectively. PAO with 7-8 composed vesicles. Labrum with 7 setae and 4 prelabral ones. Labium of AC-type, but terminal setae on papillae C slightly thinner, guard setae as usual for genus: 7(6) long (b3-4, d3-4, e1-3) and 4 spiniform (a1, b1-2 and d2) ones, a1 clearly longer and thicker than others. Proximal part of labium with (5)6 setae, mentum and submentum with 4 and 5 setae, respectively. Maxillary palp simple, with 2 sublobal setae.

Pseudocellar formula (pso) as follows, dorsal: 32/133/33343, ventral: 1/000/0000, parapseudocelli (psx) invisible. Each upper subcoxa with one pso. Localization of pso as in Fig. 32. Granulation fine and uniform, slightly enlarged granules often present around pso on last abdominal terga. Dorsal chaetotaxy almost symmetrical, setae smooth and clearly differentiated especially on abdominal tip, in more anterior parts of body macro and microsetae mainly differing in shape, sensilla distinct on terga and less evident on sterna: 1/022/221111 (dorsal) and 2/000/00011 (ventral) (Figs 32-33), thickened sensillum present also on coxae of Lg.3. Th.1 with 6+6 setae. Lateral microsensilla present only on Th.2. Unpaired dorsal seta d0 on head absent, Abd.4 with m0 and p0, Abd.5 with p0, Abd.6 dorsally with one axial macroseta and 1+1 prespinal microsetae (Fig. 32). Thoracic sterna with 0-1-1 setae on each side of linea ventralis, ventral chaetotaxy of abdomen as in Fig. 33. Abd.3 sternum unclearly divided, anterior subsegment without setae. Furca reduced to a small area of fine granulation situated at contact with border between Abd.3-4, with 2+2 small posterior setae arranged in two rows, manubrial area with 4+4 setae set in two rows (Fig. 33). Ventral tube with 6+6(7) distal setae, proximal ones at corpus base absent. Upper subcoxae usually with 3-(3)4-4, tibiotarsi with 17-17-16 setae: distal rows with 9 setae (7 A and two T-setae), row B with 7-7-6 setae, setae M absent but Y present (Fig. 36). Unguis simple, with neither inner nor lateral tooth, unguiculus with indistinct basal lamella, clearly shorter than unguis (Fig. 36).Anal spine rather strong (about as long as 0.6-0.7 U3), set on unclear papillae (Fig. 35).

Affinities.

Due to the presence of four guard setae in AO, Sensillonychiurus vitimicus sp. n. is the most similar to Sensillonychiurus mirus sp. n. and Sensillonychiurus amuricus sp. n. All these three species have many other characteristics in common (see Table 1), but Sensillonychiurus vitimicus sp. n. can easily be distinguished by the presence of setae on thoracic sterna (a presumed apomorphic condition within Onychiuridae according to Fjellberg (1998).

Etymology.

The new species was named after its terra typica.

Distribution.

Known from several biotopes in vicinity of the type locality.

One more species of the genus Sensillonychiurus was found on Kamchatka (vicinity of Petropavlovsk, sandy sea beach with weed debris, leg. L. Lobkova). It differs from Sensillonychiurus virginis in having setiform anal spines, from Sensillonychiurus geminus by the absence of lateral ms on Th.3. The lack of material (only a single female is available) did not allow us to describe it, but it is listed in the key and in Table 1 as Sensillonychiurus sp.

Key to the known species of Sensillonychiurus Pomorski & Sveenkova, 2006