Tegnacus unicornutus, Pye, Daniel R. L., 2012

Pye, Daniel R. L., 2012, New eriophyoid mites (Acari: Prostigmata: Eriophyoidea) in Britain: one new genus, four new species, 19 new records and two incursions, Zootaxa 3578, pp. 43-68 : 55-59

Tegnacus unicornutus n. sp.

( Figs. 7–12 )

FEMALE: (n=7). Body fusiform, 173 (170–183), 50 (50–57) wide. Gnathosoma 14 (11–16), projecting forward and down, setae d 3 (3–4), simple. Prodorsal shield 51 (48–51), 47 (47–54) wide, heavily pitted, with a broad rounded lobe over gnathosomal base. Underneath lobe and above palps, a transverse medially acuminate ridge forming a horn-like projection. Tubercles sc ahead of rear shield margin, plicate, projecting sc setae centrad and upward, 22 (21–22) apart; sc setae 7 (7–8). Leg I 25 (24–27); femur 10 (9–10), seta bv I 7 (5–10); genu 4 (3–4), seta l ʺ 9 (8–12); tibia 5 (4–5), seta l ʹ 2 (1–2); tarsus 5 (5–6), seta ft ʹ 13 (7–13), seta ft ʺ 17 (12–18); seta u ʹ 4 (4–5); tarsal solenidion ω 6 (5–7), with an oval knob distally; empodium simple, apical rays with flattened, splayed tips, 5 (4–5), 4-rayed. Leg II 20 (20–23); femur 9 (7–9), seta bv 9 (5–10); genu 2 (2), seta l ʺ absent; tibia 3 (3–4); tarsus 5 (5), seta ft ʹ 3 (2–3), seta ft ʺ 17 (14–17); seta u ʹ 3 (2–4); tarsal solenidion ω 7 (5–7); empodium simple, apical rays with flattened, splayed tips, 5 (4–5), 4-rayed. Coxae 1 and 2 unornamented, smooth. Setae 1b 6 (5–7), 10 (10–11) apart; setae 1a 19 (12–19), 7 (6–7) apart; setae 2a 23 (18–25), 22 (20–22) apart; tubercles 1b and 1a 6 (6–7) apart; tubercles 1a and 2a 9 (7–9) apart. Coxigenital region with 12 (12–13) annuli. Opisthosoma with 16 (16) dorsal annuli, with a broad and raised longitudinal ridge, fading to posterior, annuli heavily pitted, with rounded projections underneath the lateral margin; 58 (54–60) ventral annuli, ventral microtubercles small and longitudinally elongate, annuli completely microtuberculate. Setae c2 13 (12–15), on annulus 6 (6–7), 41 (39–41) apart; setae d 36 (23–40), on annulus 16 (16–19), 26 (24–26) apart; setae e 9 (7–10), on annulus 32 (30–33), 11 (10–12) apart; setae f 13 (12–14), on annulus 54 (50–56), 10 (9–11) apart, 4 (4) from rear. Setae h2 34 (33–37), 8 (7–9) apart; setae h1 2 (1–2), 5 (4–5) apart; h2 and h1 tubercles 2 (2) apart. Genital coverflap with 4 (2–6) short longitudinal lines, 10 (8–10), 20 (17–20) wide. Setae 3a 9 (9–11), 12 (11–13) apart.

MALE: (n=2). Similar to female. Body fusiform 143–162, 45–53 wide. Gnathosoma projecting forward and down, 12–15, setae d 2–3. Prodorsal shield 45–48, 44–52 wide, ornamentation same as female. Tubercles sc slightly ahead of rear shield margin, same as female, 17–18 apart; setae sc 6–7. Leg I 20–21, femur 8–9, seta bv 7–9; genu 3, seta l ʺ 10–15; tibia 5, seta l ʹ 1–2; tarsus 4–5, seta ft ʹ 11–12, seta ft ʺ 16–17; seta u ʹ 3–4; tarsal solenidion ω 6; empodium simple, 5, 4-rayed on each side, same as female. Leg II 18–19, femur 7–10, seta bv 7–8; genu 2, seta l” absent; tibia 3–4; tarsus 5, seta ft ʹ 2, seta ft ʺ 14–16; seta u ʹ 3–4; tarsal solenidion ω 4–6; empodium simple, 4–5, 4- rayed on each side, same as female. Coxae ornamented same as female. Setae 1b 4–5, 9–11 apart; setae 1a 13–14, 6 apart; setae 2a 20–26, 19–20 apart; tubercles 1b and 1a 7 apart; tubercles 1a and 2a 8–9 apart. Coxigenital region with 10–12 annuli. Opisthosoma with 15–16 dorsal annuli, ornamented same as female; 43–50 ventral annuli, microtubercles same as female. Setae c 2 10–12, on annulus 2, 32–37 apart; setae d 21–32, on annulus 10–11, 21–21 apart; setae e 6–9, on annulus 20–24, 9–10 apart; setae f 12–14, on annulus 39–46, 9–11 apart, 5 from rear. Setae h2 37–42, 7 apart; setae h1 1–2, 4 apart; h2 and h1 tubercles 2 apart. Genital shield ornamented with fine granules, with short lines basally in a circular pattern, 11, 16–17 wide. Setae 3a 7–8, 13–15 apart, eugenital setae tiny.

DEUTOGYNE FEMALE: (n=8). Deutogyne female almost morphologically identical to protogyne. With 16 heavily pitted dorsal annuli, 52–57 ventral annuli, and with the same leg and opisthosomal chaetotaxy and 4-rayed empodia. Deutogyne only differs by having a reduced, although variable, number of ventral microtubercles, larger and more rounded ventral microtubercles, and with a smooth genital coverflap, with no longitudinal lines ( Fig. 12 A).

Host plant. Carpinus betulus L. ( Betulaceae ).

Relation to the host. Vagrant on the under surface of the leaves, causing no apparent damage.

Type locality. England, North Yorkshire, Knaresborough (54° 0ʹ 28.08ʺ N, 1° 28ʹ 17.4ʺ W), collected by T. Prior and R. Lawson, 14.vii.2010.

Type material. Holotype female, on one slide, and nine further paratype slides, each of one specimen, have been deposited at the Natural History Museum, London. Forty seven paratype slides, each with one specimen, have been retained in the collections of Fera.

Etymology. The specific name, unicornutus , is derived from the Latin ' uni ' meaning single, and ' cornu ' meaning horn or tusk, relating to the horn-like projection above the palps.

Figures

FIGURE 7. Semi-schematic line drawings of Tegnacus unicornutus n. gen & n. sp.: A. Full dorsal view; B. Coxigenital region of protogyne female; C. Internal female genitalia; D. External male genital shield; E. Empodium. Scale bar: 20 µm for A; 10 µm for B, C & D; 2 µm for E.

FIGURE 8. Semi-schematic line drawings of Tegnacus unicornutus n. gen & n. sp.: A. Full lateral view of protogyne female; B. Lateral annuli and microtubercles; C. Lateral view of horn-like projection underneath prodorsal shield lobe; D. Leg I; E. Leg II. Scale bar: 20 µm for A; 5 µm for B, C, D & E.

FIGURE 9. Digital micrographs of Tegnacus unicornutus n. gen & n. sp.: A. Anterior prodorsal shield of female; B. Coxigenital region of protogyne female. Scale bars 10 µm.

FIGURE 10. Digital micrographs of Tegnacus unicornutus n. gen & n. sp., lateral view of anterior region of protogyne female: A. Cross section of gnathosoma showing horn-like projection; B. Lateral opisthosoma showing short first dorsal annulus. Scale bar 10 µm for both.

FIGURE 11. Digital micrographs of Tegnacus unicornutus n. gen & n. sp., lateral view of anterior region of male: A. Cross section of gnathosoma showing horn-like projection; B. Lateral opisthosoma showing short first dorsal annulus. Scale bar 10 µm for both.

FIGURE 12. Digital micrographs of Tegnacus unicornutus n. gen & n. sp.: A. Coxigenital region of deutogyne female; B. Coxigenital region of male. Scale bars 10 µm.