Shevtchenkella serrata ( Nalepa 1892 )

Chetverikov, Philipp E., Desnitskiy, Alexey G., Klimov, Pavel B., Ozman-Sullivan, Sebahat K., Romanovich, Anna E. & Sukhareva, Sogdiana I., 2023, Tuerkayana rotundum, Zoological Studies 62 (35), pp. 1-18 : 3-7

Shevtchenkella serrata ( Nalepa 1892) ( Figs. 1 , 2 , 3 )

Tegonotus serratus – Nalepa 1892: 333–335, pl. 13, figs. 7b, 8, 9. Oxypleurites serratus – Nalepa 1898: 68; Roivainen 1947: 39, fig. 22. Oxypleurites obtusus – Roivainen 1947: 38, fig. 21 (new synonymy). Shevtchenkella serrata – Petanović, Stanković 1999: 67.

PROTOGYNE (n = 10), supplementary description ( Fig. 1 ). Body fusiform, subtriangular, whitish or slightly yellowish, 180–207, 72–79 wide at the level of seta c2. Prodorsal shield semicircular, 49–56, 70–77 wide, with large apically rounded frontal lobe 10–12, 18–22 wide. Posterolateral margin of prodorsal shield with indistinct acuminate projection ( Fig. 1C ). Cuticle of prodorsal shield with numerous round microgranulations. Median line absent, two faint incomplete admedians and traces of putative incomplete submedians present on prodorsal shield ( Fig. 1D ). Epicoxal areas with microtubercules and thin striae. Scapular setae sc 5–8, 25–28 apart. Gnathosoma short, directed obliquely forward, 18–21, ep 2–3, d 5–7, ν 0.5–1; chelicera 13–15. Leg I 31–34, femur 10–12, bv 9–11; genu 5–6, l'' 17–22; tibia 7–8; l' 2–4; tarsus 5–6, u' 2–3, slightly angled, ft' 17–22, ft'' 25–29, solenidion ω 6–7 with spherical knob apically, empodium (em) 6–7, 4/4-rayed, each ray except of the rays of apical pair with one subray each ( Fig. 1A ). Leg II 30–33, femur 10–11, bv 8–11; genu 5–6, l'' 3–4; tibia 7–8; tarsus 5–6, u' 2–3, slightly angled, ft' 4–6, ft'' 20–24, solenidion ω 6–7 with spherical knob apically, empodium (em) 6–7, 4/4-rayed, similar to empodium I. Infracapitular plate rounded anteriorly, microtuberculated, 11–13, 15–18 wide; sternal line distinct, 10–12. Coxal plates with numerous microtubercles and thin striae. Setae 1b 6–8, 13–14 apart; 1a 16–19, 9–11 apart; 2a 31–38, 27–28 apart; 2–3 incomplete and 6–8 complete coxigenital annuli before epigynium. External genitalia. Genital coverflap rounded posteriorly, 10–13, 23–25 wide, with 10–12 longitudinal ridges; setae 3a 10–12, 16–18 apart; basal coverflap and adjacent area (homologous to the pregenital plate sensu Flechtmann et al. 2015) with short curved lines and microtubercles. Opisthosoma with 19–20 dorsal and 65–74 microtuberculated ventral annuli. Anterior 12–13 dorsal annuli with lateral spine-like projections; 2nd, 3rd, 4th, 5th, 7th and 9th dorsal annulus with a small subtriangular medial plate slightly overlapping next dorsal annulus. Dorsal annuli with numerous thin longitudinal ridges. Setal lengths: c2 23– 28, d 60–68 very thin in distal half, e 8–12, f 20–25, h1 about 0.5, h2 60–70; 11–12 annuli from the rear margin of coxa II to c2; 12–14 annuli between c2 and d; 17–20 annuli between d and e; 18–23 annuli between e and f; 5–6 annuli between f and h2.

Male (n = 3): Body shaped similarly to protogynes but notably shorter, 141–152, 69–75 wide at the level of seta c2. Opisthosoma with 19–21 dorsal and 66–69 ventral annuli. Genital area 11–13, 20–22 wide; 3a 9–11, 16–17 apart.

GenBank data (protogynes): ON920305 (Cox 1).

M a t e r i a l e x a m i n e d: Numerous adults and immatures from the slide series E4701, E4702 and E4703 collected on 17 July 2021 from the lower leaf surfaces of Acer platanoides L. ( Sapindaceae ) in Russia: Leningrad Prov., Gatchina distr., vil. Vyritza, coll. P.E. Chetverikov, slide series, mites in vials with 96% ethanol. All slides and ethanol material (mites in vials filled with 96% ethanol) have been deposited in the Acarological Collection of the Zoological Institute of the Russian Academy of Sciences (ZIN RAS) in Saint-Petersburg, Russia.

Remarks: The protogyne of S. serrata has been frequently reported as a vagrant on the lower leaf surface of various Acer spp. in different European countries ( Petanović and Stanković 1999; Farkas 1965; Roivainen 1947; Skoracka et al. 2005). The protogynes from our material were very similar to those from Finland ( Roivainen 1947, p. 39, fig. 22), except that our specimens had a larger number of ventral annuli (65–74 vs. 50).

DEUTOGYNE (n = 10, Figs. 2 , 3 ): Body elongated, non-flattened, bright orange, 229–250, 62–67 wide at the level of seta c2. Prodorsal shield subtriangular 41–46, 53–58 wide, with acuminated frontal lobe 8–10, 10–12 wide. Cuticle of prodorsal shield with numerous tiny round cavities (putative pores leading to wax glands, Fig. 3A ). Distinct curved transverse line resembling a flattened letter “U” present between tubercles of sc. Longitudinal lines (median, admedians and submedians) absent. Epicoxal areas smooth. Scapular setae sc 11–15, 24–27 apart. Gnathosoma directed obliquely forward, 19–21, ep 2–3, d 6–8, ν about 0.5; chelicera 15–17. In two specimens, the outlines of a short suboral fork (sensu Chetverikov and Bolton 2016) embedded in the ventral wall of the proboscis were discernible ( Fig. 3F, G, H ). The fork was comprised of a stalk about 3 ( Fig. 3H , arrow) and two leaf-shaped plates about 2 × 1–1.5 wide ( Fig. 3F, G, H , arrows), and similar to suboral forks described earlier in other eriophyoids ( Chetverikov and Bolton 2016).

Leg I 37–40, femur 11–12, bv 10–13; genu 5–6, l'' 12–18; tibia 8–9, l' 4–5; tarsus 6–8, u' 3–5, ft' 19–24, ft'' 23–28, solenidion ω 8–9 with spherical knob apically, empodium (em) 8–10, 4/4-rayed, rays and medial shaft of the empodium wide, flattened. Leg II 36–38, femur 10–12, bv 10–12; genu 5–6, l'' 7–9; tibia 7–9; tarsus 6–7, u' 3–4, ft' 5–7, ft'' 16–22, solenidion ω 8–9 with spherical knob apically, empodium (em) 8–10, 4/4-rayed, similar to empodium I. Infracapitular plate rounded anteriorly, smooth, 12–14, 15–17 wide; sternal line distinct, 10–12. Coxal plates without distinct ornamentation. Setae 1b 7–10, 12–14 apart; 1a 18–24, 10–11 apart; 2a 38–47, 26–28 apart; 2–3 incomplete and 5–6 complete coxigenital annuli before epigynium.

External genitalia: Genital coverflap oblong, 12–14, 23–25 wide, with 10–11 longitudinal ridges; setae 3a 14–17, 14–16 apart; basal coverflap with round microtubercles. Internal genitalia (n = 4). Spermathecae globose, about 6–7 in diameter; spermathecal tubes short, subspherical, about 1.5–2; spermathecal process not apparent; longitudinal bridge 9–11, anterior (transverse) genital apodeme bell-shaped, with 2–3 longitudinal ridges on each side.

Opisthosoma with 15–18 dorsal and 64–73 ventral annuli. Dorsal annuli slightly curved and smooth. Ventral annuli in anterior half of opisthosoma smooth or with traces of very faint microtubercles, ventral annuli in posterior half of opisthosoma bearing more distinct subconical microtubercles; last 3–4 ventral telosomal annuli with elongate microtubercles. Setal lengths: c2 20–26, d 58–69 very thin in distal half, e 10–12, f 29– 35, h1 about 0.5, h2 85–98; 12–14 annuli from the rear margin of coxa II to c2; 13–15 annuli between c2 and d; 16–19 annuli between d and e; 18–22 annuli between e and f; and 4–5 annuli between f and h2.

GenBank data (deutogynes): ON920306 (Cox 1).

Material examined: Numerous females from the slide series E4677 and E4678, collected on 15 August 2021 from the lower leaf surface of Acer platanoides L. ( Sapindaceae ) in Russia: Leningrad Prov., Gatchina distr., vil. Vyritza, coll. P.E. Chetverikov. All slides and ethanol material (mites in vials filled with 96% ethanol) have been deposited in the Acarological Collection of ZIN RAS (Saint-Petersburg, Russia).

Remarks: Using the morphological key of Amrine et al. (2003), rather than Shevtchenkella , the deutogyne conforms to Anthocoptes , a genus in the same subfamily, Phyllocoptinae . The tribes that Shevtchenkella and Anthocoptes belong to ( Tegonotini and Anthocoptini , respectively) are primarily differentiated by the presence or absence of lateral lobes or spine-like projections, as shown in the protogyne of S. serrata ( Fig. 1C, E, F ), but absent in the deutogyne ( Fig. 3 ). In contrast to the protogynes, the deutogynes have smooth dorsal annuli without lateral projections and medial plates, smooth prodorsal shield, flat paddle-like empodia, and more elongated body proportions. The deutogynes from our material very closely approximate Oxypleurites obtusus Roivainen 1947 which was described in sympatry with S. serrata from the lower leaf surface of A. platanoides in Finland, except that they were notably larger (229–250 vs. 160–175) and had an acuminated vs. blunt frontal lobe. We consider Oxypleurites obtusus Roivainen 1947 to be the deutogyne of S. serrata and treat it as a junior synonym of S. serrata ( Nalepa 1892) .

Figures

Fig. 1. DIC LM images of protogynes of Shevtchenkella serrata. A, empodium I. B, tarsal solenidion I. C, lateral view of opisthosoma. D, prodorsal shield. E, dorsal view of protogyne. F, dorsal view of male. G, ventral view of protogyne. Scale bars: A, B = 3 µm; C = 20 µm; D = 15 µm; E, F = 70 µm, G = 30 µm.

Fig. 2. Drawings of deutogyne of Shevtchenkella serrata. A, dorsal view of body. B, leg II. C, leg I. D, empodium I. E, tarsal solenidion I. F, internal genitalia. G, prodorsal shield. H, coxigenital area. Scale bars: A, H = 25 µm; B, C, D, E, F = 10 µm; G = 15 µm.

Fig. 3. DIC LM images of deutogyne of Shevtchenkella serrata. A, prodorsal shield; B, empodium I; C, tarsal solenidion I; D, dorsal view of entire mite; E, ventral view of entire mite; F, G, H, gnathosoma shown in three different planes from dorsal (F) to ventral (H). White arrows in Fig. 3. F, G, H indicate putative suboral fork. Scale bars: A = 15 µm; B, C = 10 µm; D, E = 60 µm; F, G, H = 5 µm.