Epitrimerus chaenomeli, Soika, Grażyna & Wozińska, Anna, 2016

Soika, Grażyna & Wozińska, Anna, 2016, A new species of eriophyoid mite (Acari: Trombidiformes: Eriophyoidea) on Chaenomeles x superba (Frahm) Rehder (Rosaceae), Zootaxa 4184 (3), pp. 458-470 : 460-468

Epitrimerus chaenomeli n. sp.

( Figs 1‒4 )

Diagnosis: E. chaenomeli n. sp. is the first eriophyoid mite to be found on the plant genus Chaenomeles (Rosaceae) and is distinguished by its prodorsal shield pattern, which is distinctive in having two pairs of anterior cells, and one cell from each pair on either side of the median longitudinal cell. E. chaenomeli n. sp. is also unique in having submedian lines I running almost directly back between the dorsal tubercles and submedian lines II on both sides of the shield, moreover, the lateral lobes are not prominent. This species can also be distinguished by the presence of longitudinal lines and dashes on coxal plates I and a few short transverse lines on coxal plates II. Both protogyne and deutogyne females of E. chaenomeli n. sp. are characterized by a 4- rayed empodium.

Description. PROTOGYNE FEMALE ( Figs 1 & 2 ) (n=10 ‒ holotype and 9 paratypes). Body spindleform, 172 (165‒188); wide 68 (64‒69). Gnathosom a 21 (18‒21), curved downward, dorsal pedipalpal genual setae d 9 (8‒11), palpcoxal seta ep 3 (3–4), seta v 2, cheliceral stylets 17 (15‒17). Prodorsal shield subtriangular, 46 (46‒50), 59 (54‒59) wide with frontal lobe rounded 8 (8‒10); ornamentation: network of lines composed of granules. Median line present in rear fifth of shield, joined to admedians by dart-shaped mark. Admedian lines entire, begin at anterior margin of prodorsal shield, run parallel to each other, along almost whole length of shield: in posterior 1/5 of shield diverging, forming one longitudinal cell along centre of shield. Submedian lines I begin from anterior frontal lobe, run almost directly back between dorsal tubercles. Submedian line I and admedian line connected by two short transverse lines. First transverse line joins submedian line I and admedian line about one third of the way along their length and second transverse line joins them about halfway along their length, forming three separate cells. Submedian lines II located on both sides of shield. On anterior part of shield submedian line II runs parallel to submedian line I. Submedian line II branches about one third of the way along prodorsal shield length: inner branch reaches submedian line I, forming one cell, outer branch runs parallel to lateral margin. Submedian line II crossed by diagonal lines, for a length of about one quarter of prodorsal shield, forming five cells on each side of shield. Lateral lobes not prominent. Scapular tubercles ahead of rear margin 2 (2–3), 19 (18–20) apart, scapular setae sc 9 (7–9) projecting mediad. Legs with usual setae. Leg I 30 (30–32); femur 9 (9–12), basiventral femoral seta bv 9 (7–12), genu 6 (5–7), antaxial genual seta l ″ 25 (19–25); tibia 8 (8–9), paraxial tibial seta l ′ 5 (5–7); tarsus 6 (6–7), seta ft ′ 19 (16–22), ft ″ 23 (18–24), u ′ 6 (5–6); solenidion ω 7 (7–8), knobbed; empodium 6 (5–7), simple, 4-rayed. Leg II 27 (27–29); femur 10 (9–10), basiventral femoral seta bv 10 (10–12); genu 5 (5–6), antaxial genual seta l″ 10 (9–12); tibia 6 (6–7); tarsus 6 (6–7), setae: ft ″ 6 (5–8), ft ′ 18 (17–21), u ′ 4 (4–6); solenidion ω 7 (6–8), knobbed; empodium 7 (6–7), simple, 4-rayed. Coxal plates I not contiguous with longitudinal lines and dashes, coxal plates II with few short transverse lines, setae 1b 10 (8–11), 12 (12–13) apart; setae 1 a 21 (14–21), 10 (9–11) apart; setae 2a 43 (28–43), 26 (24–27) apart; distance between setae 1b and 1a 10 (8–10), distance between setae 1a and 2a 8 (8–9). External genitalia 12 (11–13), 21 (20–22) wide, genital coverflap with 10 (10–12) striae; setae 3a 32 (30–38), 15 (15–16) apart. Opisthosoma with wide median and two lateral longitudinal ridges. Total dorsal annuli 46 (43–47) with oval microtubercles on ridges, placed on rear margin, area between median ridge and lateral ridges of dorsal opisthosoma smooth; total ventral annuli 68 (61–69) with microtubercles rounded, placed on rear annuli margin except for posterior annuli on which microtubercles elongated. 11 (10–12) coxigenital annuli. Setae c2 26 (24–30), 49 (48–51) apart, on 10 (9–11th) annulus; setae d 49 (37–62), 30 (27–30) apart, on 25 (22–25th) annulus; setae e 34 (23–38), 14 (13–25) apart, on 45 (39–45th) annulus; setae f 26 (20–32), 22 (21–25) apart, on 63 (56–63th) annulus, 5–6th annulus from rear. Setae h1 3 (2–3), 5 (4–6) apart; setae h2 58 (40–58), 11 (9–11) apart; distance between h1 and h2 3 (2–3).

DEUTOGYNE FEMALE (n= 11 specimens) ( Figs 3 & 4 ): body spindleform, 150–182; width 65–72. Gnathosoma 19–22, curved downward, dorsal pedipalpal genual seta d 6–10, palpcoxal seta ep 4–6, seta v 2–3, cheliceral stylets 15–16. Prodorsal shield subtriangular, 43–47, 49–57 wide with frontal lobe rounded 9‒11. Shield pattern: smooth with admedian lines beginning from the side of frontal anterior lobe and running almost straight back to area between dorsal tubercles. Tubercles of setae sc 2–3. Base of tubercles extending forward from rear margin; 16–21 apart, seta sc 8–10. Legs with all usual segments and setae present. Leg I 30–32; femur 10–12, femoral setae bv 8–12; genu 5–7, genual setae l″ 18–25; tibia 6–8, tibial setae l ′ 5–7; tarsus 6–7, tarsal setae ft ′ 16– 22, setae ft ″ 18–21, setae u ′ 5–7; solenidion ω 6–7, knobbed; empodium 5–7, simple, 4-rayed. Leg II 27–29; femur 9–11, femoral setae bv 10–12; genu 5–6, genual setae l ″ 7–8; tibia 5–6; tarsus 6–7, setae: tarsal setae ft ′ 6–8, setae ft ″ 17–21, u ′ 5–6; solenidion ω 7–8, knobbed; empodium 5–6, simple, 4-rayed. Coxal plates not contiguous and smooth. Setae 1b 9–10, 11–13 apart; setae 1a 16–24, 9–10 apart; setae 2a 28 –38, 23–27 apart; distance between setae 1b and 1a 9–10, distance between setae 1a and 2a 8–9. External genitalia 11–13, 20–23 wide, genital coverflap with 8–10 longitudinal striae; setae 3a 27–39, 13–16 apart. Opisthosoma with 44–47 dorsal annuli and 49–53 ventral annuli, 10–12 coxigenital annuli. Dorsal and ventral annuli smooth, except for last 10 ventral annuli, which have elongated microtubercles. Setae c 2 23–34, 47–54 apart, on 8th annulus; setae d 35–70, 29–30 apart, on 18–22nd annulus; setae e 25–40, 13–16 apart, on 29–34th annulus; setae f 25–30, 36–42 apart, on 45–50th annulus, 5–6th annulus from rear. Setae h1 3–4, 5–6 apart; setae h2 44–61, 9–11 apart; distance between h1 and h2 2–3.

MALE (n= 5 specimens): body spindleform, 153–174; width 55–67. Gnathosoma 17–20, curved downward, dorsal pedipalpal genual setae d 6–9, palpcoxal seta ep 3–4, seta v 2, cheliceral stylets 14–15. Prodorsal shield subtriangular, 43–47 with frontal lobe rounded 6–8, 48–56 wide; with similar design to protogyne. Tubercles of setae sc ahead of rear margin 2–3, 15–16 apart, setae sc 7–9. Legs with usual series setae. Leg I 27–32; femur 8– 10, basiventral femoral seta bv 8–10; genu 5–6, seta, antaxial genual seta l ″ 21–24; tibia 7–8, seta l ′ 4–7; tarsus 5– 6, seta ft ″ 18–23, seta ft ′ 14–19, u ′ 3–4; solenidion ω 6–7, knobbed; empodium 5–6, simple, 4-rayed. Leg II 24–29; femur 9–10, basiventral femoral seta bv 7–9; genu 4–6, antaxial genual seta l ′ 6–11; tibia 6–7; tarsus 6, setae: ft ″ 13–21, ft ′ 5–11, u ′ 3–4; solenidion ω 6–7, knobbed; empodium 5–6, simple, 4-rayed. Coxal plates I not contiguous with longitudinal lines and dashes, coxal plates II with few short transverse lines. Setae 1b 8–11, 11–13 apart; setae 1a 16–20, 9–10 apart; setae 2a 24–36, 21–24 apart; distance between setae 1b and 1a 8–9, distance between setae 1a and 2a 7–10. External genitalia 19–20 wide, surface below eugenital setae with granules; setae 3a 16–21, 14–17 apart. Opisthosoma similar to female protogyne with longitudinal ridges, wide median and two lateral ridges. Total dorsal annuli with 40–42 dorsal with oval microtubercles on ridges placed on rear margin, areas between median ridge and lateral ridges of dorsal opisthosoma smooth and 61–63 ventral annuli with rounded microtubercles placed on rear annuli margin, on posterior annuli microtubercles elongated, 9–10 coxigenital annuli. Setae c 2 24–30, 44–47 apart, on 11th annulus; setae d 37–44, 27–30 apart, on 20–23th annulus; setae e 25– 30, 13–16 apart, on 36–39th annulus; setae f 21–31, 19–24 apart, on 56–58th annulus, 5–6th annulus from rear. Setae h1 2–3, 5 apart; setae h2 32–62, 9–10 apart; distance between h1 and h2 2–3.

NYMPH (n= 4 specimens), ( Figure 5 ): body spindleform, 116–134; width 51–57. Gnathosoma 13–18, curved downward, dorsal pedipalpal genual setae d 4–6, palpcoxal seta ep 3–4, seta v 2, cheliceral stylets 13–14. Prodorsal shield subtriangular, 40–45 with frontal lobe rounded 5–7, 42–47 wide; ornamentation: median line present only on rear fifth of prodorsal shield, admedian lines distinct, running in an almost straight line to area between the dorsal tubercles. Granules on side of prodorsal shield create network. Tubercles of setae sc ahead of rear margin14–16 apart, scapular setae sc 5–6. Legs with series setae. Leg I 20–25; femur 6–7, basiventral femoral seta bv 6–7, genu 3–4, antaxial genual seta l ″ 15–17; tibia 5–6, tibial seta l ′ 3–4; tarsus 4, setae: ft ″ 11–16, ft ′ 9–14, u ′ 3–4; solenidion ω 4–5, knobbed; empodium 4–5, simple, 4-rayed. Leg II 18–22; femur 6–8, basiventral femoral seta bv 6–7; genu 3–4, seta l ″ 5–7; tibia 4–5; tarsus 4–5, seta ft″ 9–16, ft ′ 8–9, u ′ 2; solenidion ω 5–6, knobbed; empodium 4, simple, 4-rayed. Coxal plates I are not contiguous with longitudinal lines and dashes. Coxal plates II have a few short transversal lines, setae 1b 4–6, 9–10 apart; setae 1a 12–17, 7–9 apart; setae 2a 18–26, 17–26 apart; distance between setae 1b and 1a 8–10, distance between setae 1a and 2a 7–8. Setae 3a 16–21, 14–17 apart. Opisthosoma with 50–52 dorsal and 52–58 ventral annuli, 8–9 coxigenital annuli. Dorsal annuli with oval microtubercles, placed on rear margin, ventral annuli with microtubercles rounded on posterior annuli microtubercles elongated, placed on rear annuli margin. Setae c 2 14–18, 37–43 apart, on 11th annulus; setae d 16– 34, 19–22 apart, on 20–23th annulus; setae e 17–20, 12–16 apart, on 32–36th annulus; setae f 14–19, 18–19 apart, on 48–53th annulus, 6th annulus from rear. Setae h1 1–2, 4 apart; setae h2 32–39, 7–8 apart; distance between h1 and h2 2.

Type host. Chaenomeles x superba (Frahm) Rehder and C. x superba ‘Crimson and Gold’ ( Rosaceae ).

Type locality. The Botanical Garden of the Polish Academy of Sciences in Powsin, (52°6'26,59"N 21°5'41,83"E).

Type material. Female holotype, 28 female protogyne, 56 female deutogyne, 11 male and 11 nymph paratypes collected by the authors at different times from Chaenomeles x superba , cultivar Crimson and Gold: 14 protogyne female and 5 male, July 31, 2013. 21 deutogyne females, August 27, 2013, 35 deutogyne females, 7 nymphs, July 31, 2014; 8 female protogynes, 4 males, 4 nymphs, May 11, 2015; 8 protogynes, 2 males, June 10, 2015.

Other material and locality: 63 protogynes, 17 deutogynes, 13 males and 3 nymphs collected by the authors at different times from Chaenomeles x superba in the Rogów Arboretum of the Warsaw University of Life Sciences (51°49'20,33"N 19°54'07,09"E): 1 protogyne female, May 21, 2013; 19 protogyne females, 7 deutogyne females, 2 males and 3 nymphs, July 19, 2013; 22 protogyne females, 1 deutogyne female, 4 males, July 10, 2014; 9 deutogyne females, April 4, 2014; 5 protogyne females, 3 males, July 19, 2015; 16 protogyne females, 4 males, July 10, 2015.

Relation to the host plant. During the period from May to June, eriophyoid mites fed on the lower side of leaves and no damage was observed on the leaves. However, in the second half of July slight rusting on the under surfaces of infested leaf blades was visible ( Figure 6 ). Females of this species winter at the base of leaf stalks on one and two-year-old shoots ( Figure 7 ). In Spring (at the end of April), deutogynes leave their wintering sites and move to the leaves to start feeding and laying eggs. In May and June, mainly protogynes, larvae and males were found on the leaves. The first deutogynes of the new generation appear on leaves during July, at the end of this month and during August, eriophyoid mites go to their wintering sites.

Etymology. The specific name is derived from the Latin noun of host plant.

Differential diagnosis and remarks. Currently there are seven Epitrimerus species with 4-rayed empodia which are known to inhabit rosaceous plants: E. virginiana Keifer, 1959 , E. demissae Keifer, 1959 , E. crataegifolius Styer, 1975 , E. chilesi Keifer, 1966 , E. herhericus Bagdasarian, 1967 , E. pirifoliae Keifer, 1938 and E. pyri ( Nalepa, 1891) . When E. chaenomeli n. sp. is compared to the descriptions, line drawings and measurements of the above species, it has many similarities with E. virginiana , which was collected from Prunus virginiana . In both species the pattern on the prodorsal shield is created by granules and lines, the median line is present in the rear fifth of the shield and joined to the admedians by a dart-shaped mark, the admedian lines begin at the front edge of the prodorsal shield and run along the whole length of the shield, and on the anterior part of the shield they are subparallel and then diverge towards the rear, forming one longitudinal cell along the centre of the shield. On the prodorsal shield of both E. virginiana and E. chaenomeli n. sp. the admedian and submedian lines I are connected by two transverse lines forming three pairs of cells in the central part of the shield.

However the newly described species differs from E virginiana by the shape of frontal lobe of the prodorsal shield, which is rounded, whereas in E. virginiana Keifer it is sharp. This new species can also be differentiated from E. virginiana by the ornamentation of the prodorsal shield. The prodorsal shield of E. chaenomeli shows two pairs of cells in the anterior prodorsal shield, whereas in E. virginiana only one pair of anterior cells is present. The submedian lines I in E. chaenomeli n. sp. run almost directly back between the dorsal tubercles while in E.

virginiana the submedian lines I run outside of the dorsal tubercles. Apart from the above differences, the two species can also be distinguished by the presence of submedian line II, which E. virginiana lacks. Also the new species has a network of five distinct cells, clearly visible on each side of the prodorsal shield, in contrast to E. virginiana , which has seven cells. Also, in the new species, coxal plates I have longitudinal lines and dashes, and coxal plates II have a few short transverse lines while in E. virginiana , coxal plates I and II are lined with granules. Additionally, setae c2, d, e and 3a of the new species are longer than in E. virginiana ; seta c2 is 24‒30 µm in new species vs 20 µm in E. virginiana ; first ventral seta (d) 37‒62 µm in new species vs 20 µm in E. virginiana ; third ventral seta (e) 23‒38 µm in new species vs 18 µm in E. virginiana ; genital seta (3a) 30‒38 µm in new species vs 20 µm in E. virginiana . Both protogyne and deutogyne females of the new species have 4-rayed empodia, however deutogynes of E. virginiana have a 5-rayed empodium.

Figures

FIGURE 1. Epitrimerus chaenomeli n. sp. Protogyne female: D — Dorsal mite; IG — Internal genitalia; L 1 — Leg I, L 2 — Leg II; CG — Coxigenital region; SD — Lateral view of anterior region of female; em — empodium (enlarged); GM — Genital male region. Scale bar: 50 µm for D, CG, SA; 20 µm for GM; 15 µm for L 1 & L 2; 10 µm for IG.

FIGURE 2. Digital micrographs of Epitrimerus chaenomeli n. sp. Protogyne female: A — Dorsal view; B ‒ Ventral view; C ‒ Lateral anterior region; D ‒ genital region of male. Scale bar: 50 µm for A, B & D; 25 µm for C.

FIGURE 3. Epitrimerus chaenomeli n. sp. Deutogyne female: D — Dorsal mite; IG—Internal genitalia; CG—Coxigenital region; SD — Lateral view of anterior region; em — empodium (enlarged). Scale bar: 50 µm for D, CG & SD; 10 µm for IG.

FIGURE 4. Digital micrographs of Epitrimerus chaenomeli n. sp. Deutogyne female: A — Dorsal view; B ‒ Ventral view; C — Internal female genitalia; D — Legs. Scale bar: 50 µm for A & B, 25 µm for C & D.

FIGURE 5. Digital micrographs of Epitrimerus chaenomeli n. sp. Nymph: A — Dorsal view; B ‒ Ventral view. Scale bar 50 µm for both.

FIGURE 6. Feeding symptoms of Epitrimerus chaenomeli n. sp. on the leaves of Chaenomeles superba, cultivar Crimson and Gold.

FIGURE 7. Deutogyne females of Epitrimerus chaenomeli n. sp. at the base of leaf stalks.