Oligaphorura ussurica Sun & Shveenkova & Xie & Babenko 2019, sp. nov.

Oligaphorura ussurica Shveenkova & Babenko, sp. nov.

Figs 13–19, Tables 1, 2

Type material. Holotype, female on slide, Far East of Russia, Ussuriysky State Nature Reserve, Komarovskoye Forest District, Grabovaya Nipple [N 43.6367°, E 132.3499°], 383 m alt., mixed forest on slope, litter, 24.07.2016, leg. N. Kuznetsova & M. Potapov.

Paratypes, female and 2 males, same State Reserve, Komarovskoye Forest District, Turova Nipple, Khripunovsky Pass [N 43.6481°, E 132.3515°], 207 m alt., Pinus koraiensis forest on slope, litter, 23.07.2016, leg. N. Kuznetsova & M. Potapov. Types are kept in the collection of the Department of Zoology & Ecology, Moscow State Pedagogical University.

Description. Size 0.75–0.80 mm in females, 0.6–0.7 mm in males; holotype length about 0.8 mm., color white in alcohol. Body shape cylindrical. Granulation regular, slightly coarser around dorsal pso (10–11 granules) located on head and Abd. IV–V (Fig. 13).

Number of pso: 4(1+3)2/144/5(6)5554 (dorsally) and 11/000/0000 (ventrally) (Fig. 13, 14). Anterior pso on head located as follows: one inside and three outside antennal area. Number of ventral psx: 0/000/222301+ 1 m (Fig. 13, 17). Upper Sc of legs I–III with one pso each and 1, 2, 2 (?3) psx, respectively. Pseudopore present as usual, sometimes not clearly seen.

Antennae somewhat shorter than head. Ant. IV with two slightly thickened S-chaetae, subapical organite present, microsensillum located in proximal row of chaetae (Fig. 15). AIIIO consisting of 5 papillae, 5 guard chaetae, 2 sensory rods, 2 granulated clubs (external one larger) and lateral ms (Fig. 15, 16). Ant. I–II with 8 and 13 chaetae, respectively. Antennal area well marked, with fine uniform granulation. PAO located laterally in cuticular furrow, with 4 (3) lobes, slightly or 1.5 times larger than nearest pso. Maxilla unmodified. Maxillary palp simple with 1 basal chaeta and 2 sublobals. Labrum with 4/342 chaetae. Labium with 6 proximal, 4 basomedian, 6 basolateral chaetae and 10 guards (6 long, 4 spiniform), terminal sensilla of papillae A and C thickened (labium of AC type) (Fig. 19).

Dorsal chaetae poorly differentiated into macro- and microchaetae, symmetrical in general (Fig. 13). S-chaetae slightly marked and distributed as follows: 2/011/222111 (dorsally), 2/000/000100 (ventrally) and 0, 0, 1 on lower Sc. Head with two axial unpaired chaetae a0 and a0’, d0 absent as usual for genus. Chaetae p1 on head at level with p2. Th. I with 7+7 dorsal chaetae. Lateral ms present on both Th. II–III. Terga of Th. II–Abd. III with 3–4 pairs of axial chaetae. Axial chaetotaxy of Abd. IV variable with either unpaired chaeta m0 or paired m1 chaetae. On Abd. VI chaeta a0 as long as p0, chaetae a1 about 0.8 of chaeta a0, and a1 shorter than a2 (~0.5 a2). Thoracic sterna without chaetae. Ventral chaetotaxy of abdomen as in Fig. 17.

Upper Sc I–III with 4, (4)5, 5 chaetae, respectively. Tibiotarsal chaetotaxy most complete of genus with 20–20– 19 chaetae, respectively: distal whorl (T+A) with 11 chaetae, 7 B-chaetae (B7 absent only on Ti 3), unpaired chaeta M and one chaeta of C-whorl. Unguis with small lateral teeth (sometimes indistinct), unguiculus narrow with weak basal lamella, about 0.6 times as long as inner edge of unguis (Fig. 18). VT with 6–7+6–7 proximal chaetae and 2+2 at its base. Furca reduced to small cuticular fold with 2+2 axial chaetae in two rows posteriorly, also two manubrial rows of chaetae present behind; in other words, furcal area, according to Paśnik & Weiner (2017), with four rows of chaetae: 1+1 dental chaetae and three rows of manubrial chaetae. Each of lateral anal valves with a0, 2a1 chaetae, upper valve with a0, 2b1, 2b2 and 5 chaetae in c-row (b0 and a1 absent). Anal spines short, set on tiny papillae.

Etymology. The species is named after Ussuriysky Nature Reserve, an area of its type locality.

Affinities. The most characteristic features of O. ussurica sp. nov. are the presence of 4+4 pso at antennal base together with developed anal spines. Such combination of characters rather rarely occurs among Oligaphorurini although is known for a number of Asian forms, i.e. O. montana Weiner, 1994, O. pseudomontana Sun & Wu, 2012 (in: Sun & Wu 2012b) and O. chankaensis (Sun & Wu, 2012; in: Sun & Wu 2012c). These species, together with O. ussurica sp. nov. and O. kedroviensis sp. nov. (see description below), can be combined into a distinct montana - group, most probably united closely related Asian forms and characterized by the presence of 4+4 pso at antennal base (of them only one anterior pso inside Ant. basis), both Th. II-III with ms, full tibiotarsal chaetotaxy with 11 chaetae in distal whorls, furcal remnant with cuticular fold and 2+2 posterior chaetae and full-sized anal spines. Oligaphorura ussurica sp. nov. differs from the other known species of this group (excepting O. kedroviensis sp. nov., see below) by the presence of only 2+2 posterior pso and axial chaetae a0’on the head. O. ussurica sp. nov. can also be easily distinguished by the number of abdominal pso, i.e. 5(6) 5554 in O. ussurica sp. nov. vs 54453 in O. montana and 54464 in O. pseudomontana. Only O. chankaensis have a comparable number of abdominal pso [5556(7)4(5-6)] with O. ussurica sp. nov. but these two species clearly differ in the labial type: ABC in O. chankaensis vs AC in O. ussurica sp. nov. Main differences with O. kedroviensis sp. nov. are listed in Table 1 and remarks to the latter species.

Distribution and ecology. The species is still known only from litter of mixed and pine forests of the Southern Primorye.

Remarks: *—This chaeta [a0’] is present in all adult type specimens of both new species, but absent in a single available juvenile.

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Remarks: * – W.Weiner, pers. com.