1✉ Tyumen State University, Tyumen, 6 Volodarskogo Str., 625003 Russia.
2Tyumen State University, Tyumen, 6 Volodarskogo Str., 625003 Russia.
2023 - Volume: 63 Issue: 1 pages: 67-76https://doi.org/10.24349/dxkj-4dl4
Linotetranidae is a small group of phytophagous mites distributed on all continents, except Antarctica. Linotetranidae inhabit mostly dryland soils and associated with crown and roots of grasses (Walter et al. 2009). Until now, the family Linotetranidae comprises four genera and 18 described species (Meyer and Ueckermann 1997; Beard and Walter 2004; Tassi et al. 2020). The genus Linotetranus Berlese, 1910 is the largest in the family and includes 14 described species, namely: L. cylindricus Berlese, 1910; L. achrous Baker and Pritchard, 1953; L. protractulus Athias-Henriot, 1961; L. mirabebensis André, 1996; L. amiculus Meyer and Ueckermann, 1997; L. annae Meyer and Ueckermann, 1997; L. edenvillensis Meyer and Ueckermann, 1997; L. ramosus Meyer and Ueckermann, 1997; L. niknami Bagheri and Haddad, 2008; L. anatolicus Doğan and Dönel, 2010; L. astragalusi Khanjani et al., 2011; L. iraniensis Khanjani et al., 2011; L. eghbaliani Khanjani et al., 2012; and L. faemensis Tassi and Duarte, 2020 (Berlese 1910; Baker and Pritchard 1953; Athias-Henrio 1961; André 1996; Meyer and Ueckermann, 1997; Bagheri et al. 2008; Doğan et al. 2010; Khanjani et al. 2011, 2012; Tassi et al. 2020). In the Palaearctic Linotetranidae is currently known only from southern regions: Italy, Turkey and Iran (Berlese 1910; Bagheri et al. 2008; Doğan et al. 2010; Khanjani et al. 2011, 2012).
Here we describe and illustrate the first representative of the family Linotetranidae from Russia and northernmost in Palaearctic.
The mite specimens were collected from a soil sample using Berlese funnels. Most of collected mite specimens were cleared in lactic acid and mounted in Hoyer's medium. Several specimens were preserved in 96% ethanol. The terminology follows that of Lindquist (1985). All measurements are given in micrometers (μm) for holotype and range of measurements for five paratypes (in parentheses). For leg chaetotaxy, the number of solenidia is given in parentheses. For SEM microscopy several alcohol-preserved mites were dried in a JFD 320 freeze drying device (JEOL, Japan), dusted with gold and scanned with a JEOL–JSM-6510LV SEM microscope. Mite morphology was studied using a Carl Zeiss AxioImager A2 (Carl Zeiss, Germany) compound microscope with phase contrast and differential interference contrast (DIC) illumination.
ZIRAS—Zoological Institute of Russian Academy of Sciences, St. Petersburg, Russia, TSUM Z—Tyumen State University, Museum of Zoology, Tyumen, Russia
Type species: Linotetranus cylindricus Berlese, 1910, by original designation.
Female — (Figs 1–6). Body elongate. Length of idiosoma 325 (315–330), width 155 (145–170).
Gnathosoma – (Figs 2, 5B, C). Palpal setation: Tr 0, Fe 1 (d), Ge 0, Ti 2 (d, l″), Ta 5(1) (a, b, c, ul′, ul″ϛ, ω). All setae of femur and tibia weakly barbed; all tarsal setae smooth; seta ul″ blunt-tipped, eupathid-like, other tarsal setae pointed; solenidion ω ovate in outline (Fig. 5C). Palpal supracoxal setae (ep) short, peg-like. Subcapitulum elongate, finely striated (Fig. 5B), with one pair of subcapitular setae m and three pairs of adoral setae or1-or3; all setae pointed; setae or2 very short and smooth, other setae weakly barbed.
Idiosomal dorsum – (Figs 1A, 4A, B). All dorsal shields with distinct elongate reticulate pattern, except for smooth area posteriad setal row f (Fig. 4A, B); hysterosoma with transverse furrows anteriad setae d1 and posteriad setae e1–e3. Setae e4 present; all dorsal setae barbed; setae v1 not modified, slender and barbed; setae f2 weakly blunt-tipped, other setae pointed. Length of dorsal setae: v1 22 (20–25), v2 44 (43–46), sc1 80 (73–83), sc2 93 (88–95), c1 23 (23–28), c2 44 (35–48), c3 94 (76–94), c4 87 (80–89), d1 20 (20–24), d2 32 (32–41), d3 78 (72–79), e1 13 (10–14), e2 37 (34–45), e3 64 (58–68), e4 40 (33–43), f1 16 (15–18), f2 24 (24–25), f3 120 (119–121), h1 33 (29–33), h2 135 (126–135), h3 65 (61–66), h4 34 (30–34).
Idiosomal venter – (Figs 1B, 4C, D, 5A, 6). Propodosomal venter finely striated between legs I–II and with ovate microsculpture posteriad legs; metapodosomal venter with elongate reticulate pattern (Fig. 4D); genital and anal areas finely striated, other parts of ventral opisthosoma with ovate microsculpture. All ventral setae pointed; setae 1a, 3a, 3b, 4a, 4b, ag1, ag2, g1–g3 smooth; setae ps1–3 weakly barbed; setae 1b, 1c, 2b and 2c distinctly barbed. Internal genitalia with long and narrow insemination canal (Fig. 6). Length of ventral setae: 1a 92 (88–96), 1b 27 (26–28), 1c 21 (17–21), 2b 19 (19–37), 2c 64 (62–67), 3a 38 (38–41), 3b 18 (18–19), 4a 39 (30–39), 4b 18 (17–19), ag1 30 (27–30), ag2 16 (16–18), g1 16 (15–16), g2 9 (9–10), g3 8 (8–13), ps1 16 (15–16), ps2 15 (14–16), ps3 13 (12–13).
Legs – (Figs 3, 5D). Leg I (Figs 3A, 5D). Leg setation: Tr 1 (v′), Fe 5 (d, l′, l″, v′, bv″), Ge 5 (d, l′, l″, v′, v″), Ti 5(1) (d, l′, l″, v′, v″, φ), Ta 11(2) (p′ξ, p″ξ, tc′, tc″ξ, ft′, ft″, a′, a″, u′, u″, pl″, ω1, ω2). All solenidia ovate in outline (Fig. 5D); solenidion φ located ventrally anterolaterad seta v″; length of solenidia: ω1 6 (6), ω2 4 (4), φ 3 (3). Setae (p) and tc″ of tarsus smooth, blunt-tipped, eupathid-like; setae (u) smooth and pointed; other setae barbed and pointed. Setae (tc) situated on short protuberances. Leg supracoxal seta (el) short, peg-like. Leg II (Fig. 3B). Leg setation: Tr 1 (v′), Fe 3 (d, v′, bv″), Ge 2 (l′, l″), Ti 4 (d, l″, v′, v″), Ta 7(1) (tc′, tc″, ft′, ft″, u′, u″, pl″, ω). Solenidion ω 6 (5–6) ovate in outline. All setae barbed; seta l′ of genu weakly blunt-tipped; other setae pointed. Leg III (Fig. 3C). Leg setation: Tr 1 (v′), Fe 2 (d, ev′), Ge 1 (v′), Ti 3 (d, v′, v″), Ta 4 (ft′, ft″, u′, u″). All setae barbed; setae (v) of tibia and ft″ of tarsus weakly blunt-tipped; other setae pointed. Leg IV (Fig. 3D). Leg setation: Tr 0, Fe 1 (ev′), Ge 0, Ti 4 (d, l″, v′, v″), Ta 4 (ft′, ft″, u′, u″). All setae barbed; setae (v) of tibia and ft″ of tarsus weakly blunt-tipped; other setae pointed.
Male and immatures unknown.
Holotype female, slide ZISP T-Lin-1, Russia, Kurgan Region, Petuknovsky District, vicinity of lake Medvezh′ye, 14 October 2022, soil in the steppe, 55°14′11″N 68°01′15″E, coll. A. A. Khaustov and V.A. Khaustov; paratypes: 32 females, same data.
The holotype female and two paratypes females are deposited in the collection of ZIRAS; other paratypes are deposited in the collection of the TSUM Z.
Female of the new species is most similar to Linotetranus astragalusi and L. eghbaliani, described from Iran (Khanjani et al. 2011, 2012) sharing the following characters: setae e4 present, three pairs of genital setae, palpgenu without seta, palptibia with two setae, genu I with five setae, setae h2 the longest dorsal setae. The new species differs from L. eghbaliani in having setae v1 not modified (vs. setae v1 bifurcate in distal part in L. eghbaliani); in having seta d of tibia I very long, subequal to l″ of tibia I (d almost twice shorter than l″ in L. eghbaliani); and in having different setal lengths sc2 88–95, d2 32–41, d3 72–79, e2 34–45, f2 24–25, h1 29–33, h4 30–34 (vs. sc2 75–79, d2 50–57, d3 87–89, e2 55–60, f2 32–34, h1 41–45, h4 41–43 in L. eghbaliani). The new species differs from L. astragalusi in having seta ft′ on tarsi III and IV more than twice longer than ft″ (vs. setae ft′ and ft″ on tarsi III and IV subequal in L. astragalusi); in having seta pl″ on tarsus II distinctly longer than combined length of tibia and tarsus II (vs. seta pl″ on tarsus II approximately as long as tarsus II in L. astragalusi); in having seta v′ on femur II shorter than length of femur II (vs. seta v′ on femur II almost as long as combined length of femur and genu II in L. astragalusi); and in having different setal lengths v2 43–46, c1 23–28, d1 20–24, e2 34–45, e4 33–43, and h2 126–135 (vs. v2 32–34, c1 16–17, d1 14–16, e2 27–30, e4 27–29, and h2 152–153 in L. astragalusi).
The name of the new species sibiriensis refers to its geographical distribution in Western Siberia.
Based on females (after Tassi et al. 2020, with modifications).
1. Setae e4 absent
— Setae e4 present
2. Palpgenu with one seta
...... L. achrous
— Palpgenu without seta
...... L. faemensis
3. Three pairs of genital setae
— Two pairs of genital setae
...... L. ramosus
4. Dorsal opisthosoma posterior setae e1 smooth or with irregular striae
— Dorsal opisthosoma posterior setae e1 transversely striated
...... L. protractulus
5. Palptibia with one seta
— Palptibia with two setae
6. Palpgenu with one seta
...... L. cylindricus
— Palpgenu without seta
...... L. amiculus
7. Genu I with five setae
— Genu I with four setae
...... L. edenvillensis
8. Palpgenu without seta
— Palpgenu with seta
9. Tibia III with three setae
— Tibia III with four setae
...... L. mirabebensis
10. Setae f3 subequal or shorter than h2
— Setae f3 distinctly longer than h2
...... L. annae
11. Palptarsus with one eupathidium; hysterosoma dorsally without two pairs of smooth rosettes between setal rows d and e; bases of setae v1 almost contiguos
— Palptarsus with three eupathidia; hysterosoma dorsally with two pairs of smooth rosettes between setal rows d and e; bases of setae v1 widely separated
...... L. anatolicus
12. Setae v1 not bifurcate distally
— Setae v1 bifurcate distally
...... L. eghbaliani
13. Seta ft′ on tarsi III and IV more than twice longer than ft″; seta pl″ on tarsus II distinctly longer than combined length of tibia and tarsus II; seta v′ on femur II shorter than length of femur II
...... L. sibiriensis n. sp.
— Setae ft′ and ft″ on tarsi III and IV subequal in length; seta pl″ on tarsus II approximately as long as tarsus II; seta v′ on femur II almost as long as combined length of femur and genu II
...... L. astragalusi
14. Setae l″ on genua I and II distinctly longer than other setae on segments; setae e2 54–66
...... L. niknami
— Setae l″ on genua I and II subequal with other setae on segments; setae e2 95–115
...... L. iraniensis
During this research and using of electron microscopy we found three pairs of adoral setae in Linotetranus. One of them (designated as or2 on Fig. 2A) is very small and hardly visible in light microscope, however clearly discernible on the SEM image (Fig. 6B). Most likely these setae were missed in all previous descriptions of Linotetranidae. Three pairs of adoral setae in Linotetranidae are correlated with same number in Tetranychidae (Lindquist 1985).
In some previous articles authors designated posterolateral setae on coxisternal fields II as 2a (Beard and Walter 2004; Doğan et al. 2010; Khanjani et al. 2011, 2012; Tassi et al. 2020). Yet, according to the phylogenetic analysis of Eleutherengona provided by Bochkov et al. (2008), setae 2a are absent in the superfamilies Tetranychoidea, Raphignathoidea and Cheyletoidea. For this reason, in our work, we designated this pair of setae as 2c and homologous to those in sister-family Tenuipalpidae.
This research was supported by the cooperative agreement No. FEWZ-2021-0004 from the Russian Ministry of Science and Higher Education. The authors also thank to Dr. O.V. Kozlov (Kurgan State University, Kurgan, Russia) for the help during collecting of the samples. Authors also thank to N.A. Shulayev (Tyumen State University), for preparing SEM images.