Schizoturanius krugovae Nefediev 2022, sp. nov.

Schizoturanius krugovae sp. nov.

Figs 1, 3–46

Schizoturanius sp. 2 – Krugova et al. 2018: 341.

Material examined. Holotype male (ZMUM Rd 4671), Russia, southwestern Siberia, Altai Krai, Zmeinogorsk District, left bank of Malaya Amelikha River, 51.0655°N, 82.7754°E, 570 m a.s.l., middle and low part of very steep N slope, chern taiga (Abies sibirica forest with single Betula pendula, Caragana arborescens and Padus avium, Carex plentifully), pitfall traps, 8 June – 2 July 2016, collected by T.M. Krugova.

Paratypes: 2 males, 1 female, 5 juveniles (ASU), same data as holotype; 1 male, 1 juvenile (ASU), Russia, southwestern Siberia, Altai Krai, Charyshskoye District, left bank of Inya River, environs of abandon village of Kamyshenka, ca. 6 air-km SE of Tigirek, 51.1167°N, 83.1155°E (now included in TSNR), 585 m a.s.l., N slope, chern taiga (Abies sibirica forest with Betula pendula), pitfall traps, 18 June – 3 July 2016, collected by T.M. Krugova; 1 male (ZMUM Rd 4672, voucher D113, GenBank OM 892667), Russia, southwestern Siberia, Altai Krai, Krasnoshchiokovo District, ca. 6 air-km NW of Tigirek, right bank of Khankhara River, 51.1931°N, 82.9800°E, 920 m a.s.l., upper part of N slope, Betula pendula and Larix sibirica forest with bushes, soil sample (0–10 cm deep), 19 August 2016, collected by T.M. Krugova, L.Yu. Gruntova, V. V. Zelenskii, K. V. Smirnova, A.E. Pupkova, M.N. Terioshkina & R. V. Shcherbakova.

Diagnosis. Differs from all congeners mainly by the strongly elongated, slim and curved distal part of the gonopod endomere and its bifid apex (vs. shorter, subequal in size or less elongated, its apex never bifid in other species), and the postfemoral region of the endomere is with a thin, straight, subulate external process, which is almost nonserrate (vs. curved, hook-shaped, serrate or long, flat, not hook-shaped, serrate or even without an external process in other species).

Name. Honours Mrs. Tatyana M. Krugova, the collector and a well-known Russian myrmecologist. Noun in genitive case.

Description. Length 14.6–16.3 mm (males), 17.3 mm (paratype female), width of midbody pro- and metazonae 1.0 and 1.3 mm (males), 1.1 and 1.4 mm (paratype female), respectively. Holotype 14.6 mm long, 1.0 and 1.3 mm wide on midbody pro- and metazonae, respectively.

Body moniliform, with 20 segments (including telson) in both sexes (Fig. 1). Coloration in alcohol pale pinkish beige with darker anterior and posterior body parts, legs lighter, especially prefemora. Tegument moderately shining throughout; texture very delicately shagreened, alveolate, except convex metatergal surfaces. Prozonites (pz) with two types of cuticular ornamentation: with or without serration along rear margin of alveolae (Fig. 19, marked with arrows).

Head mostly densely pubescent, with convex genae, clypeolabral region densely setose, but occiput bare (Fig. 9). Antennae moderately long, clavate, reaching past segment 3 dorsally. Length ratios of antennomeres 1–7 as 2.0:2.4:5.0:4.0:3.4:5.2:1, width ratios as 1.3:1.3:1.3:1.4:1.4:1.7:1, respectively (Fig. 3); antennomeres 5 and 6 (a5 & a6) each with a small, compact, distodorsal group of sensilla basiconica (sb) (Fig. 3); antennomere 7 (a7) with a terminal disc (td) bearing four sensory cones (sc), each cone with 3–4 pores at its base (Fig. 4, marked with arrow), and a distodorsal group of sensilla basiconica spiniformia (sbs) (Fig. 5). Mandibular gnathal lobe as follows: external tooth (et) with large apical cusp and one smaller subapical cusp; internal tooth (it) comb-shaped, with five apically rounded cusps; 6 rows of pectinate lamellae (pl) with simple, bacilliform teeth; intermediate area (ia) with serrate papillae; molar plate (mp) with transverse ridges, its anterior fringe (af) with serrate spines apically (Figs 6, 7). Gnathochilarium (Fig. 8) typical to Polydesmida, each stipes (st) with 15 setae, each lamella lingualis (ll) with 6–8 setae.

In males, width of head (0.8–0.9 mm broad)> collum <ring 2 = 3 <4 <5 <6 = 12> 13 = 16; thereafter body gradually, but significantly tapering towards telson (0.6 mm broad). In the paratype female, width of head (1.1 mm broad)> collum <ring 2 = 3 <4 <5 <6 = 12> 13 = 16; thereafter body rather rapidly tapering towards telson (0.7 mm broad). Collum (col) transversely ovoid, ellipsoid (Fig. 9). Convex metatergal surfaces of rings 2–4 somewhat shorter than subsequent ones. Metatergal polygonal sculpture poorly-developed in adults, with three transverse rows of subsquarish bosses growing obliterate towards lateral portions of metaterga; juveniles with well-developed bosses on metaterga; each boss with a simple, very short tergal seta at its rear margin, more distinct on collum, as well as body rings 2–4 and 19, almost obliterate on midbody ones (Figs 10–15). Collum with 15–16 setae only in first row, and eight setae in each of two following rows (Fig. 9), while following metaterga with three rows of eight setae each (Figs 10–15). Frontolateral corners of paratergite 2 slightly elongated anteriorly and pointed (Fig. 16, marked with arrow); lateral edges of subsequent swollen paraterga weakly rounded, smooth, with three setae on each side. Limbus, or caudal margin of metazona (mz) with tiny serrate spikes (ss) (Fig. 19), excluding telson. Metazona 16–18 with slightly pointed tips of a couple of subsquarish bosses in row 3, closer to lateral sides of trunk, with an apical seta each (marked with arrow in Fig. 15). Epiproct process rather long, rounded at tip, carrying a couple of dorsal and lateral setae, and a group of four setiform spinnerets (sp) (some spinnerets may be broken off) (Figs 20, 21); it seems very likely that caudal projection of epiproct carrying four setiform spinnerets in all species of the genus (vs. “two apical setae” in S. levis and S. dshungaricus). Paraprocts with a couple of setae each, and hypoproct with a pair of setae (Fig. 18).

Legs generally rather long and slender, incrassate and slightly longer in males compared to females, podomere setose. Male podomeres ventrally with minute papillae (? sphaerotrichomes) on prefemora, femora, postfemora, tibiae and tarsi; prefemora papillate dorsally as well; in female, all podomeres with simple setae, these located mostly ventrally; prefemora clearly bulged dorsad only in males. Male leg-pair 1 (Fig. 22) somewhat reduced as compared to following walking legs, coxae elongate ventrally, each coxa, prefemur, femur and postfemur with a single long seta caudoventrally; tibiae and most of tarsi densely pilose on ventral surface with relatively robust setae; each claw (c) with an accessory claw (ac) ventrally (Fig. 23) (an additional minute claw has also been noted only in the original description of S. dmitriewi). Female leg-pair 1 subequal in size compared to following ones, all other characters as in male leg 1 (Fig. 24). Leg-pair 2 (Figs 25–27) in both sexes with an accessory claw (ac) ventrally (Fig. 26). Gonapophysis (gp) on male coxa 2 (cx2) relatively short, fimbriate apically (Fig. 27). Female coxae 2 (cx2) flattened, with a lateral prominence (marked with arrow in Fig. 42). Other walking legs in both sexes with normal claws devoid of accessory claws. Pregonopodal male sternum 7 enlarged, flattened, double shield-shaped, obviously protecting telopodites of gonopods mechanically (Figs 28–31).

Gonopod aperture of segment 7 enlarged, bean-shaped, with a transverse internal shelf anteriorly and a modest median projection on sternum posteriorly (Fig. 32). Sternum 9 at base of coxa 9 (cx9) with a setose conical projection (cp) extended ventrally (Figs 33, 34).

Gonopods falcate, telopodites amber-yellowish, in situ crossing each other, directed caudodorsally (Fig. 36). Gonopod coxa prominently enlarged, alveolate, with a rounded external outgrowth (ro) bearing an apical seta, as well as a digitiform outgrowth (do) and a small crest (cr) located a little more caudally; cannula region with a mesal conical outgrowth (co) (Figs 36–38). Basal (= prefemoral) part of telopodite densely setose. Distal part of telopodite deeply branched into an endomere (en) and an exomere (ex) (Figs 35–38). Endomere significantly longer than exomere, with strongly elongated, slim and curved distal part anteriad; endomere tip bifid (Fig. 40). Postfemoral region of endomere with a thin, straight, subulate external process (ep), directed caudolaterad, almost devoid of serration (Fig. 39). Pulvillus (pu) densely micropilose, supplied with a minute spinous process (msp) (= thin process in Nefediev 2019) in its mid portion (Fig. 41). Exomere thin, flattened on sides, with a blunt apex, a small, subtriangular, inner plate (sip) (= small triangular blade in Nefediev 2019) at mesal edge of its middle part (Fig. 37) and a small, oval, inner plate close to exomere’s base (oip) (Fig. 45) (the latter structure – oip – is not visible in Fig. 37, being hidden by the inner wall of gonopod coxa). Seminal groove forming a loop level to telopodite division into an endo- and an exomere, ending up on a micropilose pulvillus supplied with a subterminal accessory seminal chamber (sch) (Fig. 46).

Vulvar aperture rounded; transverse epigynal ridge (er) located behind leg-pair 2 on ventral surface of segment 3, well developed, slightly concave ventrally (Fig. 42). Vulvae bean-shaped, front surface of bursa (bu) covered with two rows of relatively large transverse folds with smooth edges (marked with arrow in Fig. 43) and long setae; operculum (op) also with long setae (Fig. 44). Vulvae devoid of spiral structures at bottom of bursa’s gutter.

Distribution. Southern parts of the Altai Krai in the territory of the Tigirek State Nature Reserve and its immediate adjacent areas (Maps 1, 2).

Remarks. A low-mountain species that inhabits the chern taiga and mixed forests at 570–920 m a.s.l. (Fig. 2). Endemic of the Russian Altais.

Despite the obvious need for a full-scale revision of Schizoturanius, the following provisional key can be proposed for all nine species of the genus currently known.

1(16) Gonopod endomere with an external process.

2(11) External process of gonopod endomere serrate.

3(4) Gonopod endomere longer than gonopod exomere…............................................... S. montivagus

4(3) Gonopod endomere shorter than gonopod exomere.

5(8) External process of gonopod endomere curved, hook-shaped. Pulvillus bare.

6(7) Lateral edge of gonopod endomere smooth. A small inner plate on gonopod exomere present….............. S. clavatipes

7(6) Lateral edge of gonopod endomere serrate. A small inner plate on gonopod exomere absent................. S. dmitriewi

8(5) External process of gonopod endomere and pulvillus different or poorly described.

9(10) External process of gonopod endomere long, flat, not hook-shaped. Pulvillus micropilose....................... S. levis

10(9) Shape of external process of gonopod endomere and pubescence of pulvillus uncertain (in the poor original description).............................................................................................. S. kitabensis

11(2) External process of gonopod endomere devoid or almost devoid of serration, straight.

12(13) Gonopod endomere subequal in size to gonopod exomere..................................... S. strongylosomoides

13(12) Gonopod endomere longer than gonopod exomere.

14(15) Gonopod endomere slightly longer than gonopod exomere......................................... S. dshungaricus

15(14) Gonopod endomere significantly longer than gonopod exomere. Endomere tip bifid................. S. krugovae sp. nov.

16(1) Gonopod endomere without an external process..................................................... S. tabescens