Зоологический журнал, 2021, T. 100, № 6, стр. 627-639

New species of the genus Oligaphorura (Collembola, Onychiuridae) from the forested steppe zone of Russia

Yu. B. Shveenkova a*, A. B. Babenko b**

a State Nature Reserve “Privolzhskaya Lesostep”
440031 Penza, Russia

b Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences
119071 Moscow, Russia

* E-mail: jushv@mail.ru
** E-mail: lsdc@mail.ru

Поступила в редакцию 11.03.2020
После доработки 19.05.2020
Принята к публикации 23.05.2020

Полный текст (PDF)

Аннотация

Four new species of the genus Oligaphorura, viz. O. mazeii sp. n., O. jiguliensis sp. n., O. imosolica sp. n. and O. psammophila sp. n., from the forested steppe zone of European Russia are described. Two former species are characterized by the full number of distal setae on the tibiotarsi, and the furcal remnant with a cuticular furrow and 1 + 1 posterior setae. Oligaphorura mazeii sp. n. is formally the most similar to O. shifangensis Liu et al. 2019, the latter species being known from China. These species differ in the type of the labium and the number of sensilla on the thoracic terga (labium of ABC-type and 022 sensilla on Th.1–3 in O. mazeii sp. n., vs AC-type and 011 sensilla in O. shifangensis). Oligaphorura jiguliensis sp. n., can easily be distinguished from other similar species with ms on Th.3, namely O. changbaiensis Sun et Wu 2012, O. shifangensis, O. uralica (Khanislamova 1986) and O. mazeii sp. n., by the absence of pso on Th.1. Oligaphorura imosolica sp. n., which prefers lower soil horizons, has only 9 distal setae on the tibiotarsi, the furcal remnant is a finely granulated area without cuticular furrow, and with 1 + 1 posterior setae. It is readily comparable with O. differens (Bagnall 1949), but is characterized by a different pattern of dorsal sensilla (poorly-developed sensilla expressed as 10/011/0001(0)1(0)0 in the new species, vs 2/011/22211 well-marked sensilla in O. differens). Oligaphorura psammophila sp. n. has 11 distal setae on the tibiotarsi, and the furcal remnant with a cuticular furrow and 2 + 2 posterior setae. It is very similar to O. tuvinica Potapov et Stebaeva 1997, but shows a different number of subcoxal pso (111 pso in the new species, vs 333 in O. tuvinica). A division of the genus into seven groups that combine species with higher rates of morphological similarity is proposed. A key to all 14 congeners known from the region under study is given.

Keywords: Taxonomy, Oligaphorurini, European part of Russia, forested steppe zone, key

The fauna of the genus Oligaphorura of the forested steppe zone of Eurasia has been most fully studied in Ukraine (Weiner, Kaprus’, 2014) and the Asian part of Russia (Khanislamova, 1986, Potapov, Stebaeva, 1997; Weiner, Kaprus’, 2014). Our long-term environmental studies on monitoring the soil animal communities in the forested steppe zone have been carried out in two regions of the European part of Russia, namely the Penza and Samara regions. Previously (Shveenkova, 2010, 2010a), only two Oligaphorura species were known for that area, i.e. the widespread O. absoloni (Börner 1901) and O. uralica (Khanislamova 1986), the latter species described from the southern Urals (Bashkiria). Recently, two more species of the genus, O. humicola Shvejonkova et Potapov 2012 and O. stojkoae (Shvejonkova et Potapov 2012), have been discovered in the chernozem soils of the same regions. This paper provides descriptions of further four new congeners, namely O. jiguliensis sp. n., O. imosolica sp. n., O. psammophila sp. n. and O. mazeii sp. n.

MORPHOLOGICAL REMARKS

Two main types of furcal remnant can be distinguished within the genus Oligaphorura Bagnall 1949. The first consists of a cuticular fold of various sizes, located ventrally in the central part of Abd.4. In the second, more reduced type, the furca is completely absent and only a field with fine integument granulations remains in its place. Apart from this, there are also two types of chaetotaxy in the so-called manubrial region, i.e. the area located between the furcal remnant and the medial pore on the Abd.4 sternum. The former, more complete variant can be interpreted either as the presence of 2 + 2 axial (dental) setae in two rows together with two posterior rows of manubrial setae (Weiner, 1996) or as 1 + 1 dental setae and three posterior rows of manubrial setae (Paśnik, Weiner, 2017). In the second type, one of these setal rows was aborted, this to be interpreted either as the conservation of 1 + 1 axial (dental) setae with two manubrial posterior rows of setae (Weiner, 1996) or as the complete absence of dental setae while maintaining three rows of manubrial setae (Paśnik, Weiner, 2017). These two chaetotaxic patterns and two types of furcal remnants appear to be independent in their evolution and their combinations lead to the existence of four types of furcal areas within the genus:

• type-S, or “schoetti”-type: a combination of the first type of furcal remnant and the first type of chaetotaxic pattern;

• type-A, or “absoloni”-type: a combination of the first type of furcal remnant together with the second type of chaetotaxic pattern;

• type-H, or “humicola”-type: a combination of the second type of furcal remnant and the first chaetotaxic pattern;

• type-D, or “differens”-type: a combination of the second type of furcal remnant and the second chaetotaxic pattern.

SUBDIVISION OF THE GENUS

Recently (Weiner, 1996; Weiner, Kaprus’, 2014), five different genera have been identified within the tribe Oligaphorurini: Archaphorura Bagnall 1949, Oligaphorura Bagnall 1949, Micraphorura Bagnall 1949, Dimorphaphorura Bagnall 1949, and Chribellphorura Weiner 1996. This division was proposed by Bagnall (1949) and over recent decades has been mainly based on such a non-adaptive character as the degree of furca reduction, which is non-functional even in its maximum development in the subfamily, while the independence of some of these genera has repeatedly been doubted (Christiansen, Bellinger, 1980; Fjellberg, 1987; Shvejonkova, Potapov, 2012; Babenko, Fjellberg, 2015). Recently a formal phylogenetic analysis of the tribe Oligaphorurini was performed and all genera of the tribe except Chribellphorura have been merged (Paśnik, Weiner, 2017) into one genus Oligaphorura, which includes at least 60 known species (Bellinger et al., 1996–2020), with this number constantly increasing (Liu et al., 2019; Sun et al., 2019). The taxonomy of Oligaphorurini is based on a combination of a limited number of morphological characters; with neither key nor unique features (autapomorphies) known which would allow us to reliably distinguish closely related lineages within the genus. There are several general or regional identification keys (e.g., Fjellberg, 1987; Babenko, Fjellberg, 2015; Paśnik, Weiner, 2017; Sun et al., 2019), all greatly facilitating an assessment of this diversity. For the same purpose, we propose a division of the genus into a number of groups that combine species with higher rates of morphological similarity. The main diagnostic characters of these species-groups are given in the Table 1.

Table 1.  

Main diagnostic characters of the species-groups within the genus Oligaphorura

Species-group Number of pso at antennal base Anal spines Number of distal setae on tibiotarsi Type of furcal area
“absoloni” 3 + 3 + 11 A
“alnus” 3 + 3 + 11 D
“groenlandica” 3 + 3 + 11 S or H
“differens” 3 + 3 +  9 D
“daii” 3 + 3 +/– 5–8 D
“montana” 4 + 4 + 11 S
“marcuzzii” 4 + 4 6–11 S or H

• The “absoloni”-group (Holarctic): O. absoloni (Börner 1901), O. kurtshevae Martynova 198111, O. pieninensis (Weiner 1988), O. uralica (Khanislamova 1986), O. changbaiensis Sun et Wu 2012, O. gamae (Buşmachiu et Weiner 2013), O. shifangensis Liu et al. 2019, O. mazeii sp. n., O. jiguliensis sp. n.

• The “alnus”-group (eastern Palaearctic): O. alnus (Fjellberg 1987), O. jingyueensis (Sun et Wu 2012), O. sanjiangensis (Sun et Wu 2012), O. inya (Weiner et Kaprus’ 2014), O. sibirica (Weiner et Kaprus’ 2014), O. pseudoinya (Weiner et Kaprus’ 2014), O. wanglangensis Sun et Xie 2019.

• The “groenlandica”-group (Holarctic): O. groenlandica (Tullberg 1877), O. schoetti (Lie-Pettersen 1896), O. tottabetsuensis (Yosii 1972), O. ursi Fjellberg 1984, O. aborigensis (Fjellberg 1987), O. interrupta (Fjellberg 1987), O. nataliae (Fjellberg 1987), O. nuda (Fjellberg 1987), O. pingicola (Fjellberg 1987), O. reversa (Fjellberg 1987), O. judithae (Weiner 1994), O. linderae (Weiner 1994), O. koreana (Weiner 1994), O. tuvinica Potapov et Stebaeva 1997, O. sabulosa Babenko 2007, O. judithnajtae Weiner et Paśnik 2017, O. psammophila sp. n.

• The “differens”-group (mainly Europe, except for O. sophyae): O. differens (Bagnall 1949), O. raxensis (Gisin 1961), O. pseudoraxensis (Nosek et Christian 1983), O. hackeri (Christian 1986), O. melittae (Christian 1993), O. irinae (Thibaud et Taraschuk 1997), O. eremia (Kaprus’ et al. 2002), O. olenae (Weiner et Kaprus’ 2014), O. sophyae (Weiner et Kaprus’ 2014), O. caucasica (Weiner et Kaprus’ 2014), O. imosolica sp. n.

• The “daii”-group (Europe): O. daii (Pomorski et al. 1998), O. chatyrdagi (Kaprus‘ et al. 2002), O. steposa (Kaprus’ et al. 2002), O. stojkoae (Shvejonkova et Potapov 2012).

• The “montana”-group (eastern Palaearctic): O. montana Weiner 1994, O. pseudomontana Sun et Wu 2012, O. chankaensis Sun et Wu 2012, O. ussurica Shveenkova et Babenko 2019, O. kedroviensis Shveenkova et Sun 2019.

• The “marcuzzii”-group (mainly Europe, except for O. ambigua): O. marcuzzii Cassagnau 1968, O. humicola Shvejonkova et Potapov 2012, O. kremenitsai Shvejonkova et Potapov 2012, O. ambigua Babenko et Fjellberg 2015.

Because these groups are entirely based on external morphology, naturally some species can be included into a particular group not because of true generic relations, but only because of convergent similarities. Only for some local groups, such as, for example, the “montana” and the “marcuzzii” groups, some genetic proximity may be suggested. The remaining groups are most likely artificial and include both related and non-related forms.

Seven known species, namely O. multiperforata (Gruia 1973), O. gela (Christiansen et Bellinger 1980), O. palissai (Yosii 1971), O. quadrituberculata (Börner 1901), O. alavensis (Simón-Benito et al. 1994), O. serratotuberculata (Stach 1933) and O. duocellata Babenko et Fjellberg 2015, could not be included into any group. For the first five species, we simply do not have the necessary information, since some key features are omitted from the original descriptions. Oligaphorura serratotuberculata is probably a group of related forms, as can be seen from differing descriptions (Stach, 1933; Pomorski, 1998; Fjellberg, 1998; Weiner, 1996; Shvejonkova, Potapov, 2012). Because O. duocellata occupies an isolated position, it may well be assigned in future to a separate group together with a similar, yet undescribed species from Yakutia.

SPECIES DESCRIPTIONS

Oligaphorura mazeii Shveenkova et Babenko sp. n. (Figs 1, 16)

Fig. 1.

Oligaphorura mazeii sp. n.: 1 – dorsal chaetotaxy; 2 antenna, different views; 3 labial palp (guards not shown); 4 ventral chaetotaxy of head; 5 ventral chaetotaxy of abdomen; 6 tip of leg 3. Scales (mm): 16 – 0.05.

Diagnosis. Body cylindrical. Dorsal sensilla on body well-marked. Anal spines relatively long (width : length as 1 : 4), set on tiny papillae. AO with 5 papillae, PAO slightly larger than nearest pso, with 3–4 lobes. Labium of ABC-type. Both Th.2–3 with lateral ms. Tibiotarsal chaetotaxy most complete of genus, distal whorls (A + T) of each Ti with 11 setae. Number of pso: 32/133/33343 (dorsal), 11/000/0000 (ventral), 111 (subcoxal). Number of ventral psx: 0/000/12(1)1(2)100+1m. A-type of furcal remnant. Abd.5 often with unpaired seta p0.

Type material. Holotype, ♀ on slide, European part of Russia, Middle Volga River Basin, Penza Region, “Privolzhskaya Lesostep” State Nature Reserve, upper reaches of Sura River, Ulmus laevis riparian deciduous forest [53.3169° N, 46.8866° E], soil (0–10 cm), 30.09.2014, leg. Yu. Shveenkova.

Paratypes: 1 ♂, 1 ♀, 6.08.2014, ibid., 2 ♀♀, 1 ♂, 29.05.2006, same Nature Reserve, middle reaches of Kadada River, near settl. Shatkino, oak (Quercus robur) forest [52.9229° N, 46.2752° E], soil (0–10 cm), 2 ♂♂, 23.05.2006, same Nature Reserve, middle reaches of Kadada River, near settl. Krasnoe Pole, oak (Quercus robur) forest [52.8169° N, 46.3929° E], soil (0–10 cm), 1 ♀, 4.10.2016, ibid., but pine (Pinus sylvestris) forest [52.8240° N, 46.3519° E], soil (0–10 cm), 5 ♀♀, 7 ♂♂, 2.06.2016, ibid., but meadow with Calamagrostis epigejos [52.8130° N, 46.3527° E], soil (40–50 cm). The types are kept in the collection of MSPU.

Description. Size 0.52–0.62 mm, holotype 0.615 mm. Colour white in alcohol. Body cylindrical. Granulation regular, slightly coarser around dorsal pso (10–12 granules) located both on head and Abd.4–5 (Fig. 1, 1).

Number of pso: 32/133/33343 (dorsal) and 11/000/0000 (ventral) (Fig. 1, 1, 4, 5). Ventral psx poorly expressed, sometimes not visible, its number as 0/000/12(1)1(2)100+1m (Fig. 1, 5). Each upper Sc of legs 1–3 with 1 pso and 1 psx.

Antennae slightly shorter than head. Ant.4 with three slightly thickened S-setae, subapical organite present, microsensillum located in proximal row of setae (Fig. 1, 2). AO on Ant.3 consisting of 5 papillae, 5 guard setae, 2 sensory rods, 2 granulated clubs (external one larger) and lateral ms. Antennal area not marked. Ant.1–2 with 8 and 14 setae, respectively. PAO located laterally in cuticular furrow, with 4(3) lobes, slightly larger than nearest pso. Maxilla unmodified. Maxillary palp simple with 1 basal seta and 2 sublobals. Labrum with 4/342 setae. Labium with 10 guards (6 long and 4 spiniform), 6 proximal, 4 basomedian and 5 basolateral setae, terminal sensilla of papillae A, B and C thickened, sensillum on papilla C slightly thinner than others (labium of ABC type) (Fig. 1, 3).

Dorsal setae poorly differentiated into macro- and microsetae, symmetrical in general (Fig. 1, 1). S-setae well marked and distributed as follows: 2/022/222111 (dorsally), 2/000/0001(0)1(0)0 (ventrally) and 0, 1, 1 on lower Sc of legs 1–3. Head with axial unpaired seta a0 and without a0', d0 absent as usual for genus. Setae p1 on head usually at level with p2. Th.1 with 7 + 7 dorsal setae. Lateral ms present on both Th.2–3. Terga of Th.2–Abd.3 with 3–4 pairs of axial setae. Abd.4 with unpaired seta m0. Abd.5 with unpaired seta p0 often present. On Abd.6 setae a0 and a1 approximately the same size, setae a2 and p0 slightly longer than a0. Thoracic sterna with 0-1-1 setae on each side of ventral line. Ventral chaetotaxy of abdomen as in Fig. 1, 4–5.

Upper subcoxae of legs 1–3 with 4(3), 5(4), 5(4) setae, respectively. Tibiotarsal chaetotaxy most complete of genus with 20–20–19 setae, respectively: distal whorls (T + A) with 11 setae, 7 B-setae (B7 absent only on Ti 3), one seta of C-whorl and unpaired seta M. Unguis without inner or lateral teeth, unguiculus narrow with narrow basal lamella, about 0.7 times as long as inner edge of unguis (Fig. 1, 6). VT with 7 + 7 proximal and 2+2 setae at base. Furcal remnant of A-type. Each of lateral anal valves with a0, 2a1 setae, unpaired valve with a0, 2b1, 2b2 and 5 setae in c-row (b0 and a1 absent). Anal spines relatively long (width: length as 1:4), set on tiny papillae.

Affinities. Oligaphorura mazeii sp. n. belongs to the “absoloni”-group, being characterized by the presence of 11 distal setae on the tibiotarsi and the furcal remnant being of A-type. Three species of the group, viz. O. absoloni, O. gamae and O. pieninensis, differ clearly from O. mazeii sp. n. by such a sound character as the absence of ms from Th.3. Two other congeners of the same species-group, O. uralica and O. changbaiensis, have more pso on Abd.1–5 (44454). Oligaphorura kurtshevae can be distinguished by an uncommon (triangular) arrangement of pso on the posterior part of the head.

Formally, O. mazeii sp. n. seems to be especially similar to O. shifangensis, the latter species from China, as both show identical pseudocellar formulae (dorsal, ventral and subcoxal), the same type of the furcal area, and ms present on both Th.2–3. However, the new species is distinctly smaller (0.52–0.62 mm, vs 1.1–1.6 mm in O. shifangensis) and has a different type of labium (ABC, vs AC in O. shifangensis). There are also several stable chaetotaxic differences between these species, for instance, the number of setae in the basolateral part of the labium (5 + 5 in O. mazeii sp. n., vs 6 + 6 in O. shifangensis) and on Th.1 (7 + 7 setae in O. mazeii sp. n., vs 8–9 + 8–9 in O. shifangensis). Apart from this, the new species differs by the number of sensilla on the thorax (022 in O. mazeii sp. n., vs 011 in O. shifangensis) and the usual presence of unpaired seta p0 on Abd.5 (absent from O. shifangensis).

Distribution and ecology. The species was registered in three separated parts of the “Privolzhskaya Lesostep” Nature Reserve, namely, in the upper reaches of Sura River (so called “Verkhnesursky” cluster) and in two different areas of the middle reaches of Kadada River (clusters “Kuncherovsky” and “Borok”). O. mazeii sp. n. inhabits various types of biotopes including forests, steppes and floodplains, everywhere clearly preferring sandy soils.

Etymology. The species is named after protozoologist Yuri Mazei, whose earlier scientific career was associated with the Penza State University. Under his initial direction, studies on soil microfauna in the “Privolzhskaya Lesostep” Nature Reserve were started.

Oligaphorura jiguliensis Shveenkova et Babenko sp. n. (Figs 2, 17)

Fig. 2.

Oligaphorura jiguliensis sp. n.: 1 dorsal chaetotaxy; 2 antenna, different views; 3 labial palp; 4 ventral chaetotaxy of head; 5 ventral chaetotaxy of abdomen; 6 – furcal area; 7 – tip of leg 3. Scales (mm): 1, 4, 5 – 0.1; 2, 3, 6, 7 – 0.05.

Diagnosis. Body cylindrical. Dorsal sensilla on body poorly marked, long and thin. Anal spines relatively long (width : length as 1 : 5), without papillae. AO with 5 papillae, PAO about as long as nearest pso, with 3–4 lobes. AC-type of labium. Both Th.2–3 with lateral ms. Each tibiotarsi with 11 distal setae. Number of pso: 32/033/33343 (dorsal), 11/000/0000 (ventral), 111 (subcoxal). Ventral psx not visible. A-type of furcal remnant. Abd.5 often with unpaired seta p0.

Type material. Holotype, ♀ on slide, European part of Russia, Middle Volga River Basin, Samara Region, “Samarskaya Luka” National Park, calcareous stone-pit, maple and birch forest [53.4059° N, 50.0794° E], soil, 02.05.2011, leg. Yu. Shveenkova.

Paratypes: ♀, ♂ and 1 juv., same location as holotype. Types are kept in the collection of the MSPU.

Description. Size 0.66–0.84 mm, holotype 0.725 mm. Colour white in alcohol. Body cylindrical. Granulation regular (Fig. 2, 1).

Number of pso: 32/033/33343 (dorsally) and 11/000/0000 (ventrally) (Fig. 2, 1, 4, 5). Each upper Sc of legs 1–3 with 1 pso. Ventral psx not visible.

Antennae slightly shorter than head. Ant. 4 with two poorly thickened S-setae, or present, ms located in proximal row of setae (Fig. 2, 2). AO on Ant.3 consisting of 5 papillae, 5 guard setae, 2 sensory rods, 2 granulated clubs (external one larger) and lateral ms. Antennal area not marked. Ant.1–2 with 8 and 15 setae, respectively. PAO located laterally in cuticular furrow, with 4(3) lobes, about as long as nearest pso. Maxilla unmodified. Maxillary palp simple with 1 basal seta and 2 sublobals. Labrum with 4/342 setae. Labium with 10 guards (6 long, 4 spiniform), 6 proximal, 4 basomedian and 5 basolateral setae, terminal sensilla of papillae A and C thickened (labium of AC type) (Fig. 2, 3).

Dorsal setae poorly differentiated into macro- and microsetae, symmetrical in general (Fig. 2, 1). S-setae poorly marked, long and thin and distributed as follows: 2/011/222(1)110 (dorsally), 2/000/00000 (ventrally) and 0, 0, 1 on lower Sc. Head with axial unpaired setae a0 and without a0', d0 absent as usual for genus. Setae p1 on head usually at level with p2. Th.1 with only 5+5 dorsal setae. Lateral ms present on both Th.1–2. Terga of Th.2–Abd.3 with 3–4 pairs of axial setae. Abd.4 with paired setae m1 or with unpaired seta m0. Unpaired seta p0 on Abd.5 often present (its localization variable – in holotype and some paratypes it moved forward to m0-position). On Abd.6 seta a0 slightly shorter than p0 but longer than a1, setae a2 more than twice the length of a1. Thoracic sterna with 0-1-1 setae on each side of ventral line. Ventral chaetotaxy of abdomen as in Fig. 2, 4, 5, 6.

Upper subcoxae of legs 1–3 with 3, 5, 5 setae, respectively. Tibiotarsal chaetotaxy most complete of genus with 20–20–19 setae, respectively: distal whorl (T + A) with 11 setae, 7 B-setae (B7 absent only on Ti 3), unpaired seta M and one seta of C-whorl. Unguis without inner or lateral teeth, unguiculus narrow with weak basal lamella, about 0.8 times as long as inner edge of unguis (Fig. 2, 7). VT with 7 + 7 proximal setae and 2 + 2 at its base. Furcal remnant of A-type (Fig. 2, 5, 6). Each of lateral anal valves with a0, 2a1 setae, upper valve with a0, 2b1, 2b2 and 5 setae in c-row (b0 and a1 absent). Anal spines thin and long, (width: length as 1 : 5) without papillae.

Affinities. O. jiguliensis sp. n. belongs to the “absoloni”-group (see above), being characterized by 11 distal setae on the tibiotarsi and the furcal remnant of A-type. Three species of this group, i.e. O. absoloni, O. gamae and O. pieninensis, differ clearly by the absence of lateral ms on Th.3. Oligaphorura kurtshevae is characterized by an uncommon triangular arrangement of pso in the posterior part of the head. Oligaphorura jiguliensis sp. n. can easily be distinguished from others species of the “absoloni”-group, namely O. changbaiensis, O. shifangensis, O. uralica and O. mazeii sp. n., by the absence of pso on Th.1.

Distribution and ecology. The new species is only known from the type locality where it was found in a maple-birch forest at the foot of rocks.

Etymology. The species is named after the Zhiguli (Jiguli in Latin transliteration) Hills of “Samarskaya Luka” National Park.

Oligaphorura imosolica Shveenkova et Babenko sp. n. (Figs 3, 16)

Fig. 3.

Oligaphorura imosolica sp. n.: 1 – dorsal chaetotaxy; 2 – antenna, different views; 3 – labial palp; 4 – ventral chaetotaxy of head; 5 – ventral chaetotaxy of abdomen; 6 – tip of leg 3. Scales (mm): 1, 4, 5 – 0.1; 2, 3, 6 – 0.05.

Diagnosis. Body cylindrical. Dorsal sensilla short, poorly marked. Anal spines relatively short (width : length as 1 : 3), set on tiny papillae. AO with 5 papillae, PAO slightly larger than nearest pso, with 3–4 lobes. Labium: ABC-type. Both Th.2–3 with lateral ms. Number of pso: 32/133/33343 (dorsal), 11/000/0000 (ventral). Number of ventral psx: 0/000/111100+1m. Upper Sc of legs 1–3 with 111 pso and 1(?2)22 psx, respectively. Distal whorl of each Ti with 9 setae. Furcal remnant: D-type.

Type material. Holotype, ♀ on slide, European part of Russia, Middle Volga River Basin, Penza Region, “Privolzhskaya Lesostep” State Nature Reserve, right bank of Khoper River, Padus avium forest [52.8340° N, 44.4228° E], soil (50–60 cm), 24.07.2015, leg. Yu. Shveenkova.

Paratypes: 1 ♂, same data as holotype, 8 ♀♀, 2 ♂♂, 1 juv., same Nature Reserve, upper reaches of Khoper River, meadow with Calamagrostis epigejos [52.9967° N, 44.3295° E], soil (40–50 cm), 05.06.2009, 3 ♀♀, 6 ♂♂ and 1 juv., European part of Russia, Middle Volga River Basin, Samara Region, “Samarskaya Luka” National Park, calcareous stone-pit, maple forest [53.4059° N, 50.0794° E], soil, 02.05.2011. Types are kept in the collection of the Department of Zoology & Ecology, Moscow State Pedagogical University.

Description. Size 0.58–0.73 mm, holotype 0.687 mm. Colour white in alcohol. Body cylindrical. Granulation regular, coarser on Abd.6 (8–10 granules) and around dorsal pso located on head and medial parts of terga (Fig. 3, 1).

Number of pso: 32/133/33343 (dorsal) and 11/000/0000 (ventral) (Fig. 3, 1, 4, 5). Number of ventral psx: 0/000/111100+1m, on Abd.1 psx located in lateral position (Fig. 3, 5). Upper Sc of legs 1–3 with 111 pso and 1(?2)22 psx, respectively.

Antennae slightly shorter than head. Ant.4 with two slightly thickened S-setae, or present, microsensillum located in proximal row of setae (Fig. 3, 2). AO on Ant.3 consisting of 5 papillae, 5 guard setae, 2 sensory rods, 2 granulated clubs (external one larger) and lateral ms. Antennal area slightly marked with uniform granulation. Ant.1–2 with 8 and 13 setae, respectively. PAO located laterally in cuticular furrow, with 4(3) lobes, slightly larger than nearest pso. Maxilla unmodified. Maxillary palp simple with one basal seta and 2 sublobals. Labrum with 4/342 setae. Labium with 10 guards (6 long, 4 spiniform), 6 proximal, 4 basomedian and 5 basolateral setae, terminal sensilla of papillae A, B and C thickened, the latter slightly thinner than others (labium of ABC type) (Fig. 3, 3).

Dorsal setae poorly differentiated into macro- and microsetae, symmetrical in general (Fig. 3, 1). S-setae short, poorly marked and distributed as follows: 10/011/0001(0)1(0)0 (dorsally), 2/000/000000 (ventrally) and not developed on lower Sc. Head with axial unpaired setae a0 and without a0', d0 absent as usual for genus. Setae p1 on head usually in front of p2. Th.1 with 6–7 + 6–7 dorsal setae. Lateral ms present on both Th.2–3. Terga of Th.2–Abd.3 with 3–4 pairs of axial setae. Abd.4 with unpaired seta m0. On Abd.6 setae a0, a2, p0 of approximately equal size, setae a1 as long as 1/2 of p0. Thoracic sterna with 0-1-1 setae on each side. Ventral chaetotaxy of abdomen as in Fig. 3, 4, 5.

Upper subcoxae of legs 1–3 with 3, 3(4), 3 setae, respectively. Tibiotarsal chaetotaxy with 18–18–17 setae, respectively: distal whorl (T + A) with 9 setae (setae T2 and T3 absent), 7 B-setae (B7 absent only on Ti 3), unpaired seta M and one seta of C-whorl. Unguis without inner or lateral teeth, unguiculus narrow with weak basal lamella, about 0.6 times as long as inner edge of unguis (Fig. 3, 6). VT with 6 + 6 proximal and 2 + 2 setae at its base. Furcal remnant of D-type. Each of lateral anal valves with a0, 2a1 setae, upper valve with a0, 2b1, 2b2 and 5 setae in c-row (b0 and a1 absent). Anal spines relatively short, (width: length as 1 : 3) set on tiny papillae.

Affinities. Due to only 9 distal setae on the tibiotarsi and the D-type of furcal remnant, O. imosolica sp. n. can be assigned to the “differens”-group. It is indeed very similar to O. differens, although can easily be distinguished by the different expression of dorsal sensilla, which are more numerous (2/011/22211, vs 10/011/0001(0)1(0)0 in O. imosolica sp. n.) and clearly visible only in O. differens. There are also a number of tiny, but rather stable characters that can be used for these species’ separation. Among them, the number of ventral and subcoxal psx (0/000/111100+1m and 1(?2)22 in O. imosolica sp. n., vs only 1+1 ventral psx on Abd.4 in O. differens) and the number of setae on the upper subcoxae (33(4)3 in O. imosolica sp. n., vs 445 in O. differens) and VT (6 + 6 in O. imosolica sp. n., vs 5 + 5 in O. differens). Apart from this, the new species is smaller (0.58–0.73 mm, vs 0.83–0.98).

Three other species of the “differens”-group, namely O. caucasica, O. eremia and O. hackeri, differ clearly from the new species in the absence of ms on Th.3. Both O. raxensis and O. melittae are characterized by the absence of pso from Th.1.

Further four species of the “differens”-group, O. irinae, O. olenae, O. sophyae and O. pseudoraxensis, have the same number of dorsal pso as O. imosolica sp. n. Contrary to O. imosolica sp. n., two former have pso on the abdominal sterna (0001 in O. irinae and 1111 in O. olenae), O. sophyae has only four papillae in AO, while O. pseudoraxensis is characterized by thin anal spines.

Distribution and ecology. Oligaphorura imosolica sp. n. clearly prefers lower soil horizons in both forest and steppe biotopes and, apparently, is widespread in the region under study. It was found on territories of both “Samarskaya Luka” National Park and “Privolzhskaya Lesostep” State Nature Reserve. In the latter, it was registered in two separate areas in the Khoper River basin, namely, in “Ostrovtsovsky” and “Poperechensky” clusters.

Previous records of O. irinae in the broadleaved forests of Russia (Chernov et al., 2010; Shveenkova, 2010a) belong to O. imosolica sp. n.

Etymology. The species is named after its biological preferences, “imo solo” Lat., meaning the lower, deeper soil horizons.

Oligaphorura psammophila Shveenkova et Babenko sp. n. (Figs 4, 16)

Fig. 4.

Oligaphorura psammophila sp. n.: 1 – dorsal chaetotaxy; 2 – antenna, different views; 3 – labial palp; 4 – ventral chaetotaxy of head; 5 – ventral chaetotaxy of abdomen; 6 – tip of leg 3. Scales (mm): 1, 4, 5 – 0.1; 2, 3, 6 – 0.05.

Diagnosis. Body cylindrical. Dorsal sensilla short, well-marked. Anal spines relatively short (width: length as 1 : 3), set on tiny papillae. AO with 5 papillae, PAO slightly larger than nearest pso, with 3–4 lobes. Labium: ABC-type. Tibiotarsi with 11 distal setae. Lateral ms present only on Th.2. Number of pso: 32/133/33343 (dorsal), 11/000/0000 (ventral). Number of ventral psx: 0/000/111100. Upper Sc of legs 1–3 with 111 pso and 111 psx, respectively. Furcal remnant: S-type.

Type material. Holotype, ♂ on slide, European part of Russia, Middle Volga River Basin, Penza Region, “Privolzhskaya Lesostep” State Nature Reserve, middle reaches of Kadada River, pine forest on slope [52.8213° N, 46.3465° E], soil (0–10 cm), 04.10.2018, leg. Yu. Shveenkova.

Paratypes: 1 ♂, 3 ♀, same data as holotype, 2 ♂♂, 4 ♀♀, same data as holotype, but aspen forest [52.8189° N, 46.3607° E], 04.05.2009, 2 ♂♂ (premature), same locality, but 10.10.2009. Types are kept in the collection of the Department of Zoology & Ecology, Moscow State Pedagogical University.

Description. Size 0.60–0.70 mm, holotype 0.626 mm. Colour white in alcohol. Body cylindrical. Granulation regular, slightly coarser around dorsal pso (10–12 granules) located on head and central part of body (Fig. 4, 1).

Number of pso: 32/133/33343 (dorsal) and 11/000/0000 (ventral) (Fig. 4, 1, 4, 5). Ventral psx sometimes poorly expressed, its number as 0/000/111100, on Abd.1 psx located in lateral position (Fig. 4, 5). Each upper Sc of legs 1–3 with 1 pso and 1 psx, respectively.

Antennae slightly shorter than head. Ant.4 with two slightly thickened S-setae, or present, microsensillum located in proximal row of setae (Fig. 4, 2). AO on Ant.3 consisting of 5 papillae, 5 guard setae, 2 sensory rods, 2 granulated clubs (external one larger) and lateral ms (Fig. 4, 2). Ant.1–2 with 8 and 14 setae, respectively. Antennal area not marked. PAO located laterally in cuticular furrow, with 4(3) lobes, slightly larger than nearest pso. Maxilla unmodified. Maxillary palp simple with 1 basal seta and 2 sublobals. Labrum with 4/342 setae. Labium with 10 guards (6 long, 4 spiniform), 6 proximal, 4 basomedian and 5 basolateral setae, terminal sensilla of papillae A, B and C thickened (labium of ABC type) (Fig. 4, 3).

Dorsal setae poorly differentiated into macro- and microsetae, more or less symmetrical (Fig. 4, 1). S-setae well marked and distributed as follows: 2/011/222111 (dorsally), 2/000/000000 (ventrally) and 0, 0, 1 on lower Sc. Head with axial unpaired setae a0 and without a0', d0 absent as usual for genus. Setae p1 on head usually at level with p2. Th.1 with 7 + 7 dorsal setae. Lateral ms present only on Th.2, absent on Th.3. Terga of Th.2–Abd.3 with 3–4 pairs of axial setae. Abd.4 usually with unpaired seta m0. On Abd.6 setae a0, a2, p0 of approximately equal size, and setae a1 as long as 1/2 of p0. Thoracic sterna with 0-1-1 setae on each side. Ventral chaetotaxy of abdomen as in Fig. 4, 4, 5.

Upper subcoxae of legs 1–3 with 4, 5(6), 5 setae, respectively. Tibiotarsal chaetotaxy most complete of genus with 20–20–19 setae, respectively: distal whorl (T + A) with 11 setae, 7 B-setae (B7 absent on Ti 3), unpaired seta M and one seta of C-whorl. Unguis without inner or lateral teeth, unguiculus narrow with weak basal lamella, about 0.7 times as long as inner edge of unguis (Fig. 4, 6). VT with 7 + 7 proximal and 2+2 setae at base. Furcal remnant of S-type. Each of lateral anal valves with a0, 2a1 setae, upper valve with a0, 2b1, 2b2 and 5 setae in c-row (b0 and a1 absent). Anal spines short (width: length as 1 : 3), set on tiny papillae.

Affinities. O. psammophila sp. n. is a member of the “groenlandica”-group, having 11 distal setae on the tibiotarsi and the S-type of furcal remnant. Among the known species of this group, it shares the absence of ms from Th.3 only with O. ursi, O. nataliae, O. tuvinica and O. sabulosa. The former species differs from O. psammophila sp. n. in having the A-type of labium (ABC in O. psammophila sp. n.). Oligaphorura nataliae lacks dorsal pso on Th.1. Oligaphorura tuvinica shows more subcoxal pso (333 in O. tuvinica, vs 111 in O. psammophila sp. n.), whereas O. sabulosa is characterized by a different number of pso on Abd.4.

Distribution and ecology. The species seems to have a local distribution within the “Privolzhskaya Lesostep” Nature Reserve being found only in one area, so called “Kuncherovsky” cluster. It can be treated as a psammobiont clearly preferring sandy soils in the region under study.

Etymology. The species is named after its ecological preferences, being recorded in sandy soils.

Key to the Oligaphorura species from the forested steppe zone of Russia

1 Anal spines absent............................................. 2

– Anal spines present........................................... 3

2 4 + 4 pso at antennal base, tibiotarsi with 6 distal setae.................................................. O. humicola

Species of the “marcuzzii”-group: 42/133/33354 (dorsal pso), 11/000/1111 (ventral pso), 222 (subcoxal pso), ABD labium, H-type of furcal remnant, ms on Th.3 absent, AS absent

– 3 + 3 pso at antennal base, tibiotarsi with 7 distal setae …………...........................................O. stojkoae

Species of the “daii”-group: 32/133/33343 (dorsal pso), 11/000/0000 (ventral pso), 111 (subcoxal pso), ABC labium, D-type of furcal remnant, ms on Th.3 absent, AS absent

= 3 + 3 pso at antennal base, tibiotarsi with 11 distal setae....................................... O. serratotuberculata22

Ant.3–4 fused, 32/122/33343 (dorsal pso), 11/000/11111 (ventral pso), 111 (subcoxal pso), ABC labium, ms on Th.3 present, S-type of furcal remnant, Abd.5 and 6 fused dorsally, AS absent

3 Tibiotarsi with distal 9 setae............................... 4

= Tibiotarsi with 11 distal setae............................. 5

4 AO with 5 papillae..................... O. imosolica sp. n.

Species of the “differens”-group: 32/133/33343 (dorsal pso), 11/000/0000 (ventral pso), 111 (subcoxal pso), ABC labium, D-type of furcal remnant, with ms on Th.3, 9 distal setae on tibiotarsi, dorsal sensilla poorly differentiated

– AO with 4 papillae.......................... O. sophyae

Species of the “differens”-group: 32/133/33343 (dorsal pso), 11/000/0000 (ventral pso), 111 (subcoxal pso), AC labium, D-type of furcal remnant, 9 distal setae on tibiotarsi, ms on Th.3 present

5 Furcal remnant of D-type.................................. 6

– Furcal remnant of S-type.................................. 7

= Furcal remnant A-type...................................... 8

6 Abd.4 with 4 + 4 dorsal pso.................. O. sibirica

Species of the “alnus”-group: 32/133/33343 (dorsal pso), 11/000/0000 (ventral pso), 111 (subcoxal pso), AC labium, D-type of furcal remnant, with ms on Th.3, 11 distal setae on tibiotarsi

– Abd.4 with 5 + 5 dorsal and without ventral pso.............................................................O. inya

Species of the “alnus”-group: 32/133/33353 (dorsal pso), 11/000/0000 (ventral pso), 111 (subcoxal pso), AC labium, D-type of furcal remnant, with ms on Th.3, 11 distal setae on tibiotarsi

= Abd.4 with 5 + 5 dorsal and with 1 + 1 ventral pso...................................................O. pseudoinya

Species of the “alnus”-group: 32/133/33353 (dorsal pso), 11/000/0001 (ventral pso), 111 (subcoxal pso), AC labium, D-type of furcal remnant, with ms on Th.3, 11 distal setae on tibiotarsi

7  Upper subcoxae of legs 1–3 with 3-3-3 pso............ ............................................................O. tuvinica

Species of the “groenlandica”-group: pso 32/133/ 33 343 (dorsal pso), 11/000/0000 (ventral pso), 333 (subcoxal pso), ABC labium, S-type of furcal remnant, Th.3 without ms, tibiotarsi with 11 distal setae

– Upper subcoxae with 1-1-1 pso................................ ............................................O. psammophila sp. n.

Species of the “groenlandica”-group: pso 32/133/ 33343 (dorsal pso), 11/000/0000 (ventral pso), 111 (subcoxal pso), ABC labium, S-type of furcal remnant, Th.3 without ms, tibiotarsi with 11 distal setae

8 AO with 4 short papillae, Th.3 without ms............. ............................................................O. absoloni

Species of the “absoloni”-group: 32/133/33 343 (dorsal pso), 11/000/0000 (ventral pso), 111 (subcoxal pso), AC labium, A-type of furcal remnant, tibiotarsi with 11 distal setae

– AO with 5 papillae, ms on Th.3 present.............. 9

9  Th.1 without pso......................O. jiguliensis sp. n.

Species of the “absoloni”-group: 32/033/33 343 (dorsal pso), 11/000/0000 (ventral pso), 111 (subcoxal pso), AC labium, A-type of furcal remnant, Th.3 with ms, tibiotarsi with 11 distal setae, AS thin and long, without papillae, Abd.5 often with unpaired seta p0

– With 1 + 1 pso on Th.1.....................................10

10 Thoracic sterna without setae...............O. uralica

Species of the “absoloni”-group: large species with coarse granulations, especially on Abd.6, AS strong, PAO about twice as nearest pso, 32/133/44 454 (dorsal pso), 11/000/1(2)1120 (ventral pso), 233 (subcoxal pso), AC labium, A-type of furcal remnant, Th.3 with ms, tibiotarsi with 11 distal setae

–  Thoracic sterna with 0-1-1 setae.......................... ......................................................O. mazeii sp. n.

Species of the “absoloni”-group: body small and thin, granulation uniform, AS thin, PAO about as large as nearest pso, 32/133/33343 (dorsal pso), 11/000/0000 (ventral pso), 111 (subcoxal pso), ABC labium, A-type of furcal remnant, Th.3 with ms, tibiotarsi with 11 distal setae, well-marked sensilla, Abd. 5 often with unpaired seta p0

CONCLUSIONS

Together with the newly described species, the genus Oligaphorura presently includes about 65 species and, according to Bellinger et al. (1996–2020), it is inferior in diversity only to three genera of the family Onychiuridae: Protaphorura (138 species), Deuteraphorura (83) and Thalassaphorura (67). Despite this assessment of the generic diversity is conventional because of many taxonomic problems, the high species richness of the genus Oligaphorura is beyond doubt. Equally unequivocal is its high heterogeneity. The species groups identified above probably fail to exhaust the existing intrageneric diversity. Moreover, many of them can hardly be considered natural, since they are based solely on external morphological traits. Yet they definitely facilitate the assessment of the existing generic diversity. To establish true genetic relationships, extensive molecular studies are necessary. Unfortunately, this is a rather distant perspective, but not the nearest future for the given group.

Список литературы

  1. Babenko A.B., Fjellberg A., 2015. Subdivision of the tribe Oligaphorurini in the light of new and lesser known species from North-East Russia (Collembola, Onychiuridae, Onychiurinae) // ZooKeys. V. 488. P. 47–75. https://doi.org/10.3897/zookeys.488.8123

  2. Bagnall R.S., 1949. Contribution towards a knowledge of the Onychiuridae (Collembola–Onychiuroidea). V–X. Annals and Magazine of Natural History. Series 12. V. 2 (19). P. 498–511. https://doi.org/10.1080/00222934908654001

  3. Bellinger P.F., Christiansen K.A., Janssens F., 1996–2020. Checklist of the Collembola of the World. Available on www.collembola.org [Date of access 18.02.2020]

  4. Chernov A.V., Kuznetsova N.A., Potapov, M.B., 2010. Springtail Communities (Collembola) of Eastern European Broadleaf Forests // Zoologicheskii Zhurnal. V. 89. № 5. P. 559–573 [English version: Entomological Review. 2010. V. 90. № 5. P. 556–570.] https://doi.org/10.1134/S0013873810050039

  5. Christiansen K.A., Bellinger P.F., 1980 (1981). The Collembola of North America, North of the Rio Grande (1st edition). Grinnell, Iowa: Grinnell College. P. 1–1321.

  6. Deharveng, L., 1983. Morphologie évolutive des Collemboles Neanurinae en particulier de la lignée Néanurienne. Travaux du Laboratoire d’Ecobiologie des Arthropodes Edaphiques, Toulouse. V. 4. № 2. P. 1–63.

  7. Fjellberg A., 1987. Northern species of Onychiurus Gervais, 1841, subgenus Archaphorura Bagnall, 1949 (Collembola: Onychiuridae) // Entomologica scandinavica. V. 18. P. 279–288.

  8. Fjellberg A., 1998. The Collembola of Fennoscandia and Denmark. Part. I: Poduromorpha. Fauna Entomologica Scandinavica V. 35. P. 1–183.

  9. Fjellberg A., 1999. The labial palp in Collembola // Zoologischer Anzeiger. V. 237. P. 309–330.

  10. Khanislamova G.M., 1986. New species of springtails of the genus Onychiurus (Collembola, Onychiuridae) from the Ural Mountain foothills // Zoologicheskii Zhurnal. V. 65. № 10. P. 1470–1478. [in Russian]

  11. Liu J., Gao M., Xie Zh., Sun X., 2019. Two new Onychiurid species on morels in Southwest China // Zootaxa. V. 4576. № 2. P. 367–374. https://doi.org/10.11646/zootaxa.4576.2.10

  12. Paśnik G., Weiner M.W., 2017. First phylogenetic analysis of the tribe Oligaphorurini (Collembola: Onychiuridae) inferred from morphological data, with implications for generic classification // Organisms Diversity and Evolution. V. 17. P. 619–631. https://doi.org/10.1007/s13127-017-0332-8

  13. Pomorski R.J., 1998. Onychiurinae of Poland (Collembola: Onychiuridae). Genus (Supplement), Wrocław. V. 9. P. 1–201.

  14. Potapov M.B., Stebaeva S.K., 1997. Four new species of families Onychiuridae and Isotomidae (Hexapoda, Collembola) from Ubsunur Hollow (Tuva, Russia) // Miscel.lania Zoologica. V. 20. P. 119–131.

  15. Shveenkova Yu.B., 2010. Collembolan communities (Hexapoda: Collembola) in biotopes of the foreststeppe transect of “Privolzhskaya lesostep” Reserve // Izvestiya PGPU im. V.G. Belinskogo. Natural Sciences. № 17 (21). P. 74–81 (in Russian).

  16. Shveenkova Yu.B., 2010a. Fauna and Population Structure of Springtails (Hexapoda, Collembola) in Zonal Forest-Steppe Biotopes of the Middle Volga River Basin // Entomological Review. V. 4. № 90. P. 441–458 (original Russian version: Zoologicheskii Zhurnal. V. 89. № 2. P. 1–17.

  17. Shvejonkova Yu.B., Potapov M.B., 2012. Three new species of Oligaphorurini (Collembola: Onychiuridae) without anal spines from European Part of Russia // Russian Entomological Journal. V. 20. № 4. P. 351–360.

  18. Stach J., 1933. Zwei neue Arten von Onychiurus Gerv. (Collembola) aus Polen. Bulletin de l’Académie Polonaise des Sciences et des Lettres. Classe des Sciences Mathématiques et Naturelles. Série B. Sciences Naturelles (II). Cracovie. P. 235–241.

  19. Sun X., Shveenkova Yu.B., Xie Zh., Babenko A.B., 2019. New Oligaphorura species (Collembola: Onychiuridae) from the forests of East Asia // Zootaxa. V. 4661. № 2. P. 256–270. https://doi.org/10.11646/zootaxa.4661.2.2

  20. Weiner W.M., 1996. Generic revision of Onychiurinae (Collembola: Onychiuridae) with a cladistics analysis // Annales de la Société Entomologique de France (N.S.). V. 32. № 2. P. 163–200.

  21. Weiner W.M., Kaprus’ I.J., 2014. Revision of Palearctic species of the genus Dimorphaphorura (Collembola: Onychiuridae: Onychiurinae: Oligaphorurini) with description of new species // Journal of Insect Science. V. 14. № 74. P. 1–30. https://doi.org/10.1673/031.014.74

  22. Yoshii R., 1996. Identity of some Japanese Collembola IV. “Deuteraphorura” Group of Onychiurus. Annals of the speleological research institute of Japan (Iwaizumi). V. 14. P. 1–15.

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