Psyllaphorura silvestris, Shveenkova & Babenko, 2021

Shveenkova, Yulia B. & Babenko, Anatoly B., 2021, Two new species of the genus Psyllaphorura (Collembola: Onychiuridae) from the east of European Russia, Zootaxa 4965 (1), pp. 114-128 : 115-117

Psyllaphorura silvestris sp. nov.

Figs 1–10

Type material. Russia: holotype, male, European part, Middle Volga River Basin, Samara Region, “Samarskaya Luka” National Park, calcareous stone-pit near cave, Acer and Betula forest [N 53.4059°, E 50.0794°], soil, 02.05.2011, Yu. Shveenkova leg. Paratypes: 1 female and 4 males, same data as holotype; 1 juvenile, same biotope, but 13.06.2011; 2 males, 7 females and 1 juvenile, ibid., but 04.05.2019, Yu. Shveenkova leg. The types are kept in the collection of MSPU.

Other material. 1 juvenile, European part of Russia, Penza Region, “Privolzhskaya Lesostep” State Nature Reserve, upper reaches of Sura River , floodplain Pinus forest [N 53.3169°, E 46.8866°], soil, 30.09.2014 ; 1 female and 2 juveniles, Penza Region, near Leonidovka settlement, nearby Lake “Mertvoe”, mixed forest, 21.07.2006 ; 2 juveniles, ibid., but Pinus forest. All Yu. Shveenkova leg. ; 2 females and 4 juveniles, Penza Region, Zarechny town , Populus tremula and Betula forest, 01.05.2010, T. Gorbushina leg. ; 1 male and 2 juveniles, European part of Russia, Kaluga Region, “Kaluzhskie Zaseki” State Nature Reserve, near Kireykovo settlement, broad-leaved forest, soil, 17.10.2005, A. Chernov leg. ; 1 female, Republic of Bashkortostan, foothills of southern Urals, Burzyansky Region , “Shulgan-Tash” State Nature Reserve , “Shulgan-Tash” (“ Kapova ”) Cave , 17– 23.07.2008, S. Kapralov leg. ; 2 females and 4 juveniles, Middle Urals, Sverdlovsk Region, low reaches of Serga River, left bank, “Olenyi Ruchyi” National Nature Park , “Bolshaya Arakaevskaya” Cave , moss, 08.08.2002, M. Potapov and A. Potapov leg. ; 1 male and 5 females, Mordovian Republic, Temnikovsky Region, Mordovian State Nature Reserve , floodplain Quercus robur forest, 18.08.1983, N. Kuznetsova leg.

Diagnosis. A species of the genus Psyllaphorura , which can be distinguished from the congeners due to the presence of 30/010/00123 dorsal pso (3+3 cephalic pso are located outside of antennal bases in the form of two half-arches along the axial line) and PAO with 16–22 simple vesicles. It is also characterized by: mid-sized cuticular granulation, relatively distinct dorsal sensilla, AO with 5 papillae and 4 guard setae, Ant. IV with an elongated subapical organite, labium of AC - type, only Th. II with lateral ms, furcal remnant of usual shape typical of genus with 3+3 setae, retinaculum with 1+1 teeth and a long unguiculus with a broad basal lamella.

Description. Size 1.2–1.6 mm in females, 0.9–1.3 mm in males; holotype: 1.38 mm. Colour white. Habitus typical of the genus ( Fig. 1 ), body ovoid, Abd. VI short with relatively small anal spines. Cuticular granulations not too coarse, with 9–11 cuticular granules around each pso on abdominal tip, and 11–13 granules between p1 setae on Abd. V.

Dorsal pseudocelli as 30/010/00123, 3+3 cephalic pso located outside antennal bases in two semi-arcs along axial line ( Fig. 1 ). Psx invisible.

Antennae club-like, clearly shorter than head diagonal. Antennal base distinctly marked. Ant. IV with unusually long subapical organite ( Fig. 2 ), 2–3 thickened blunt sensilla laterally and 5–6 similar sensilla on its inner side, basolateral microsensillum set in line with proximal whorl of setae. AIIIO consisting of 5 cuticular papillae, two sensory rods, two smooth sensory clubs, 4 guard setae, and lateral microsensillum ( Fig. 2 ). Ant. I–II with 10 and 13– 14 setae respectively. PAO with 16–22 simple vesicles ( Fig. 3 ). Labrum with 4/9 setae, maxillary outer lobe simple with two sublobal setae. Labium of AC type (sensillum on papilla A clearly thicker) with 7 long and 4 spiniform guards and 6 proximal setae ( Fig. 4 ). Basomedian and basolateral fields of labium with 4 and 6 setae, respectively. Usually 5+5 postlabial setae present along ventral mid line ( Fig. 5 ).

Chaetotaxy plurichaetotic and usually not symmetrical, dorsal setae slightly differentiated: most setae blunt and rather thick ( Figs. 1, 10 ), besides few pointed, thin and curved microsetae present on most terga, dorsal sensilla relatively distinct: 2(1)/021/222111, sensilla on Abd. VI located ventro-laterally on pleura ( Figs. 1, 6 ). Seta d0 on head present or absent. Th. I with up to 12 setae on each side. Only Th. II with a lateral microsensillum. Upper subcoxae of legs 1–3 prominent, with 6(7)–7(6)–7(8) setae, respectively. Abd. IV with 1–3 unpaired or paired msetae, setae p0 present also on both Abd. IV and V. Axial seta a0 on Abd.VI slightly shorter than p1 and a2, seta a2 about twice as long as a1 ( Fig. 1 ). Sterna of Th. I–III without setae along ventral line. Ventral chaetom on abdomen composed of pointed meso- and macrosetae ( Figs. 5, 6 ).

Furcal remnant as usual for genus: mucro absent, dens knob-like with 3+3 long setae, retinaculum present with 1+1 teeth ( Fig. 7 ). Chaetotaxy of furcal field in adults highly variable and usually not symmetric: in largest specimens 3–4 irregular rows of manubrial setae present posteriorly to dental remnant. VT with 8–9 distal setae on each side and without proximal setae at base ( Fig. 8 ). Tibiotarsi with complete distal whorl (7A + 4T), 7–7–6 setae in B-whorl, M seta present, C-whorl variable. Unguis toothless, unguiculus as long or slightly longer than inner edge of unguis, with wide basal lamella ( Fig. 9 ). Upper anal valve with setae a0, 2a1, 2a2, 2b1, c0, 2c1, 2c2, each lateral valve with setae a0 and 2a1 ( Fig. 6 ). AS short and conical, about as long as papillae.

Etymology. The species is named after its ecological preferences, i.e. different types of forest habitats.

Affinities. Psyllaphorura silvestris sp. nov. shares the presence of 3+3 anterior cephalic pso with only three known congeners (see Table 1), namely P. obesa , P. altaica and P. pseudopodis sp. nov., the latter species described below. Among them only in P. obesa the position of these pso is the same as in P. silvestris sp. nov., namely in the form of two separate half-arcs outside of the bases of the antennae along the midline of the head (OR-pattern, see below). Contrary, in both P. altaica and P. pseudopodis sp. nov. cephalic pso are located in a common axial group. There are also some additional similarities between P. silvestris sp. nov. and P. obesa , for instance, the presence of thoracic pso (absent in all other congeners) or rather long unguiculus with a distinct basal lamella. Despite all these similarities P. silvestris sp. nov. and P. obesa can be easily distinguished by pso formulas (30/010/00123 pso in the former vs 30/011(0)/00023 in the latter) and the shape of PAO vesicles (simple in P. silvestris sp. nov. vs compound in P. obesa ). Psyllaphorura silvestris sp. nov. is characterized by two probably unique traits that are not mentioned for all other known congeners, namely the absence of lateral microsensillum on Th. III and an unusually long subapical organite on Ant. IV.

Distribution. Apparently, the new species is widespread in the forest belt of the East-European part of Russia where it mainly inhabits riparian forests, as well as in the entrance of caves and their environs.

Figures

FIGURES 1–10. Psyllaphorura silvestris sp. nov.: 1, dorsal chaetotaxy; 2, antenna, different views; 3, PAO; 4, labial palp (small guards not shown); 5, ventral chaetotaxy of head; 6, ventral chaetotaxy of abdomen; 7, furcal remnant; 8, ventral tube; 9, tip of leg II; 10, dorsal mesosetae. Scales: Figs 1, 5, 6—0.1 mm; 2, 4, 7–9—0.05 mm; 3 – 0.025 mm; 10—0.01 mm.