Allonychiurus unisetosus, 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 : 23-24

Allonychiurus unisetosus sp. n. Figs 50-54

Material.

Holotype ♂, Russia, Tuva Republic, northern macroslope of Eastern Tannu-Ola Mt Range, vicinity Shuurmak [50°38'N, 95°18'E], spruce-larch ( Picea obovata , Larix sibirica ) forest, on larch stump under Cladonia chlorophaea , 1,450 m alt., 12.viii.1997, leg. N.V. Sedel'nikova (MSPU).

Paratypes 8♀ and ♂, same sample as holotype; 1♀, same region, stony outcrops in mountain steppe, under Xanthoparmelia somloensis and Parmelia saxatilis , 1,450 m alt., 12.viii.1997, leg. N.V. Sedel'nikova (MSPU).

Description.

Colour white. Size 0.55-0.65 mm. Body elongated, wider in region of Abd.4. Antennae about as long as head, antennal area not clearly demarcated. Ant.4 rather short and wide, 2 usual sensilla not especially thickened but distinct, a subapical organite and a basal microsensillum present. Ant.3 organ consisting of 4 low papillae, 2 sensory rods, 2 smooth sensory clubs without clear ribs, 5 guard setae, and a lateral microsensillum (Fig. 52). Ant.1 and 2 usually with 8 and 13 setae, respectively. PAO wide (length/width ratio ca 1.5), with (7)8-10 composed vesicles set close together. Labrum with 7 setae and 2 prelabral ones. Apical part of labium with thick terminal setae on papillae A, B and C (ABC - type), seta A clearly thicker, 6 long (e2 absent) and four spiniform (a1, b1-2 and d2), guard setae, a1shorter than others. Proximal field of labium with 5 setae, basal fields (mentum and submentum) with 4 and 5 setae. Maxillary palp simple, with 2 sublobal setae.

Pseudocellar formula (pso) as follows, dorsal: 32/233/33343 (Fig. 50), ventral: 11/000/0111 (one specimen with 1+2 ventral pso on Abd.4 also visible), sternum of Abd.1 with 1+1 psx on each side of VT (Fig. 53). Upper subcoxae with two pso and (2)3-(3)4-(3)4 setae, respectively. Generally granulation rather fine, but areas of clearly enlarged granules usually present around some pso and in mid and lateral parts of thorax. Dorsal chaetotaxy almost symmetrical, setae smooth and rather thick, clearly differentiated into macro and microsetae, sensilla poorly distinguishable, 1/011/222121 (dorsal) and 2/000/00010 (ventral), only lateral ones on Th.2-Abd.1 and posterior one on Abd.5 always distinct (Figs 50, 54). Sensillum on coxae of Lg.3 present. Th.1 with (4)5+5 setae. Terga of Th.2-Abd.3 with 3, Abd.4 with 2 and Abd. 5 with 1, pairs of axial microsetae, additionally each tergum with 1+1 posterior axial mesosetae set slightly out of line with microsetae. Unpaired dorsal setae: d0 on head, microseta m0 on Abd.4, microseta a0 on Abd.5, and only one macrosetae (m0) on Abd.6, supplemented by 2+2 prespinal microsetae (Figs 50, 54). Lateral microsensilla present on both Th.2-3.

Sterna of Th. 1-3 with 0-1-1 setae on each side of linea ventralis. Furca reduced to a small area of fine granulation situated at some distance from border between Abd.3-4 sterna with 2+2 small posterior setae arranged in 2 rows, manubrial area with 4+4 setae arrange in 2 rows but only one row set posteriorly to small dental setae (Fig. 53). Ventral tube usually with 1+1 frontal, 6+6 distal and 2(3) proximal setae at corpus base. Tibiotarsi with 18-18-18 setae: distal row on each leg with 9 setae (7 A and 2 T-setae), 7 setae in row B, setae M and Y present. Unguis simple, without teeth, unguiculus narrow, gradually tapering, with fine filament reaching tip of unguis. Anal spines curved and rather thin, set without papillae. MVO in reproductive males probably identical to that in Allonychiurus volinensis but in both available mature males only thickened setae present in mid-ventral section of Abd.4 (Fig. 53).

Affinities.

Allonychiurus unisetosus sp. n., Allonychiurus volinensis and Allonychiurus subvolinensis sp. n. constitutes a rather homogeneous subgroup among the known species of the volinensis-group of Allonychiurus . All of them are characterized by identical position of antennal pso with b-pseudocellus set close to midline and out of antennal area (cf. Figs 50-51 and 40). Such a position is unique for the group. Allonychiurus unisetosus sp. n. shares equal number of tibiotarsal setae (9) with Allonychiurus subvolinensis sp. n. and identical ventral chaetotaxy of thorax (0-1-1) with Allonychiurus volinensis (see Table 2) but differs from both species in having only two prelabral setae, one ventral pso on Abd.4 as a rule, only one axial macroseta on dorsal side of Abd.6 (cf. Figs 54 and 49), and clearly thinner AS.

Etymology.

The name reflects the presence of only one axial macroseta on Abd.6 in the new species separating it from similar congeners.

Distribution.

Known from several nearby localities of mountain Tuva, previously listed for the same region as Onychiurus s.str. sp. by Stebaeva et al. (2001).