Extenuipalpus quadrisetosus ( Lawrence, 1940 ), 2024

Beard, Jennifer J., Ueckermann, Edward A., Castro, Elizeu B. & Seeman, Owen D., 2024, A revision of the genus Extenuipalpus Reck, 1959 (Trombidiformes: Tetranychoidea: Tenuipalpidae), with description of a new species, Zootaxa 5417 (1), pp. 1-62 : 21-35

Extenuipalpus quadrisetosus ( Lawrence, 1940)

( Figs 13–26 )

Tenuipalpus quadrisetosus Lawrence, 1940: 114 —original designation.

Tenuipalpus gibbus Lawrence, 1943: 42 —synonymy Baker & Pritchard, 1953: 319.

Extenuipalpus quadrisetosus ( Lawrence, 1940)— new combination Reck, 1959: 467.

Extenuipalpus quadrisetosus ( Lawrence, 1940) — Mitrofanov & Strunkova, 1979: 39.

Ultratenuipalpus quadrisetosus ( Lawrence, 1940) — Mesa et al. 2009: 101.

Extenuipalpus quadrisetosus ( Lawrence, 1940) — Beard et al. 2016: 14.

Material examined. Holotype: deutonymph, ex cape quince Cryptocarya woodii Engl. ( Lauraceae ), Stella Bush (now Pigeon Valley Nature Reserve), Durban, KwaZulu-Natal, South Africa, viii.1938, no collector written on slide label ( NMSA-MIT 26221).

Other material examined. 3 females ex cape quince C. woodii ( Lauraceae ), Stella Bush (now Pigeon Valley Nature Reserve), Durban, KwaZulu-Natal, South Africa, vii.1940, no collector written on slide labels ( Lawrence (1943) lists collectors as R.F. Lawrence and M. Lavoipierre) (as T. gibbus holotype + 2 female paratypes on one slide; NMSA-MIT 26222); 1 deutonymph, 2 larvae ex C. woodii ( Lauraceae ), Stella Bush, Durban, KwaZulu-Natal, South Africa, vii.1940, no collector written on slide label ( Lawrence (1943) lists collectors as M. Lavoipierre and R.F. Lawrence) (one slide, as T. quadrisetosus ; NMSA-MIT 26225); 5 females, same data as T. gibbus holotype except vii.1941 (one slide, as T. gibbus ; NMSA-MIT 26226); 3 males, same data as T. gibbus holotype (2 slides, as T. gibbus ; NMSA-MIT 26223, 26224); 2 females, ex cape quince C. woodii ( Lauraceae ), Karkloof, Pietermartizburg, KwaZulu-Natal, South Africa, iv.1941, no collector written on slide labels (one slide, as T. gibbus ; NMSA-MIT 26228); 1 deutonymph ex C. woodii ( Lauraceae ), Karkloof, KwaZulu-Natal, South Africa, iv.1941, no collector written on slide label ( Lawrence (1943: 39) states collectors as B. Rycroft and M. Lavoipierre) (as T. quadrisetosus ; NMSA-MIT 26227) (this specimen was listed as an adult female and was used in redescription of E. quadrisetosus by Lawrence 1943). All specimens from NMSA.

Diagnosis. Female. Prodorsal setae sc1 long, cylindrical, three to four times longer than oblanceolate setae sc2; mid-prodorsum with fine arching striae/plicae. Opisthonotal setae c1, d1, e1 large, elongate oblanceolate. Cuticle finely striate on coxal fields I–II. Ventral opisthosoma with region of colliculate cuticle laterad anterior corners genital flap, extending to setae 4a. Femora IV with two setae (d, evʹ). Genua I–II with three setae (d, lʹ, lʺ). Tibiae II with five setae (d, lʹ, lʺ, vʹ, vʺ). Male. Setae v2 short, oblanceolate, slightly longer than oblanceolate setae sc1. Deutonymph. Dorsal setae sc2, c3 elongate, flagellate; femur II seta d elongate, narrow, barbed. Larva. Dorsal setae sc2, h2 elongate, flagellate; setae c3, e3 elongate.

Remarks. Lawrence (1943: 39) redescribed E. quadrisetosus using two additional specimens that he considered to be adult females, but they were both deutonymphs. Both of these deutonymph specimens were examined in this study (listed in other material examined). Interestingly, Lawrence (1943) also provides some details of what he believed was the nymphal stage of E. quadrisetosus , but did not list any nymph in the material examined section. We feel that he was most likely referring to the larvae on the same slide and one of these deutonymphs.

Description. Adult female. (10 measured). Dorsum. ( Figs 13 , 14 ). Body measurements: v2–h1 233–253 [242], sc2–sc2 161–172 [161], c3–c3 187–200 [198], f1–f1 25–34 [28], f3–f3 77–85 [79]. Anterior margin of prodorsum with broad median forked projection forming a central notch 23–32 [28], and triangular projections extending between coxae I–II. Prodorsal shield weakly developed, covered in fine arching striae/plicae medially that become oblique laterally. Prodorsum much wider than long; setae v2 and sc2 inserted in almost transverse line along anterior margin, slightly anterior to setae sc1. Opisthosoma with large, rounded, strongly sclerotised central region; sclerotised region with broadly colliculate to tuberculate cuticle, with series of broad transverse folds medially between setae c1–c1 and d1–d1; with finely striate/plicate cuticle between sclerotised region and setae f3, h1, h2 along posterior margin. Dorsal setae of various forms, finely barbed. Setae inserted around body margin much smaller and shorter than central setae, mostly narrow ovate to obovate in form, except setae e3, f3 narrow oblanceolate; setae h1, h2 broadest. Setae inserted centrally on body elongate oblanceolate to cylindrical, with setae sc1 longest. Most dorsal setae inserted on small rounded tubercles. Setal measurements: v2 20–27 [24–25], sc1 83–98 [83–86], sc2 22–33 [28–30], c1 66–75 [72–73], c3 22–28 [27–28], d1 48–58 [57–58], d3 20–25 [22–24], e1 45 –57 [54–57], e3 21 –28 [26–27], f3 21–32 [25–27], h1 32–39 [34–37], h2 34–45 [41–43].

Gnathosoma . ( Fig. 15 ). Ventral cuticle posterad infracapitular setae m 15–17 [16] with fine transverse striae/ plicae. Palp tarsus with solenidion 1–2, eupathidium 6–7 [1–2; 6]; tibiogenu with 2 setae 8–10 [9–10], 13–17 [14–16].

Venter. ( Fig. 15 ). Ventral cuticle completely finely striate/plicate, with various patterns of fine striae/plicae. With fine longitudinal striae/plicae between setae 1b–1a, on coxae I–II and broad region on lateral prosoma; with mostly transverse striae/plicae centrally between 1a–ag; striae/plicae becoming oblique between 4a and coxae III– IV; with fine longitudinal striae/plicae laterad genitoanal region; with fine transverse striae/plicae on membranous genital flap; with region of colliculate cuticle laterad anterior corners genital flap, extending to setae 4a. Setae g1–2 inserted in transverse row along posterior margin of genital flap. All setae short, fine, smooth to finely barbed, except setae 1a elongate, flagellate (difficult to measure full length). Setal measurements: 1a 117–163 [128–163], 1b 18–20 [18–19], 1c 16–18 [17–18], 2b 17–20 [19–20], 2c 19–25 [21–25], 3a 15–17 [16], 3b 17–19 [17–19], 4a 29–36 [32–34], 4b 15–18 [15–18], ag 19–28 [26–27], g1 21–27 [26–27], g2 20–25 [23–25], ps2 20–23 [22–23], ps3 23–26 [26].

Spermathecal apparatus. Not visible.

Legs. ( Fig. 16 ). Setal formulae for legs I – IV: cx 2-2-1-1, tr 1-1-1-1, fe 4-4-2-2, ge 3-3-1-0, ti 5-5-3-3, ta 9(1)- 9(1)-5-5 respectively. Leg chaetotaxy: cx I 1b, 1c; cx II 2b, 2c; cx III 3b; cx IV 4b; tr I–IV v′; fe I–II d, l′, v′, bvʺ; fe III–IV d, ev′; ge I–II d, l′, lʺ; ge III l′; ge IV nude; ti I–II d, l′, lʺ, v′, vʺ; ti III–IV d, v′, vʺ; ta I–II ft′, ftʺ, tc′, tcʺ, p′ζ, pʺζ, u′, uʺ, ωʺ; ta III–IV ft′, tc′, tcʺ, u′, uʺ. Tarsi I and II each with one abaxial solenidion ωʺ (8–10 [8–9], 8–9 [8–9], with distant companion seta ftʺ (both 8–9 [8–9]), and one pair of ventral eupathidia p′ζ–pʺζ present (all 6–7 [6–7]). Femora I–IV setae d and l′ thickened and heavily barbed; seta bvʺ on femur II much thicker and more heavily barbed than on femur I; tarsi III–IV with setae tc′–tcʺ inserted on short projections.

Adult male. (3 measured). Dorsum. ( Fig. 17A ). Body measurements: v2–h1 218–227, sc2–sc2 161–163, c3–c3 151–155, f3–f3 62–67. Anterior margin of prodorsum with broad median forked projection forming a central notch 15–20, and triangular projections extending between coxae I–II. Prodorsum and dorsal opisthosoma completely finely striate. Prodorsum as in female, covered in fine arching striae/plicae medially that become oblique laterally. Dorsal opisthosoma weakly divided into mesonotal region and pygidial region by narrow band of weak transverse striae/ plicae; with fine mostly transverse striae/plicae medially, becoming longitudinal laterally. Dorsal setae different in form to those of female and generally much smaller, finely barbed. Setae inserted around body margin more or less subequal in size and form, larger than central opisthosomal setae, mostly narrow obovate to oblanceolate in form; setae h1 broadest. Setae inserted centrally on body small, obovate. Most dorsal setae inserted on small rounded tubercles. Setal measurements: v2 18–21, sc1 15–16, sc2 22–30, c1 9–11, c3 21–24, d1 6–10 d3 20–24, e1 7 –8, e3 18 –23, f3 17–26, h1 20–23, h2 24–29.

Gnathosoma . ( Figs 17 , 18 ). Ventral cuticle posterad infracapitular setae m 15–17 with fine transverse striae/ plicae. Palp tarsus with solenidion 4–5, eupathidium 5; tibiogenu with 2 setae 8–9, 16–17.

Venter. ( Fig. 18 ). Ventral cuticle completely finely striate/plicate, with various patterns of fine striae/plicae, similar to female. With fine longitudinal striae/plicae between setae 1b–1a, on coxae I–II and lateral prosoma; with mostly transverse striae/plicae centrally between 1a–g1; striae/plicae becoming oblique between 4a and coxae III–IV. All setae short, fine, smooth to finely barbed, except setae 1a elongate, flagellate (difficult to measure full length), and ps3 modified as accessory genital stylets into a distinct elongate hemi-trullate shape with narrow basal stalk (or knife shape), inserted distally on tapered projection from genitoanal region ( Fig. 18 ). Setae g1, g2, ps2 inserted together in a row on paired flaps flanking genitoanal projection. Setal measurements: 1a 128–143, 1b 19–23, 1c 17–19, 2b 17–20, 2c 19–23, 3a 17–18, 3b 15–18, 4a 25–27, 4b 13–20, ag 18–19, g1 8–9, g2 9–10, ps2 13–15, ps3 15–17.

Aedeagus. ( Fig. 17B ). Sclerotised, elongate, extremely finely tapered (127–163), difficult to measure full length, with narrow membranous tube emerging basally, tube apparently ending in blunt bulb.

Legs. ( Fig. 19 ). Setal formulae same as adult female except extra solenidion ω′ present on ta I–II. Tarsi I and II each with two solenidia (ta I adaxial ω′ 9–11, abaxial ωʺ 12–14; ta II adaxial ω′ 9–10, abaxial ωʺ 12–14), with distant companion seta ftʺ (ta I 8–9, ta II 8), and one pair distal eupathidia p′ζ–pʺζ present (all 7). Femora I–IV setae d thickened and heavily barbed.

Deutonymph. (3 measured: T. quadrisetosus holotype + 2). Dorsum. ( Figs 20 , 21 ). Body measurements: v2–h1 252–318 [318], sc2–sc2 140–146 [146], c3–c3 189–204 [204], f3–f3 69–72 [69]. Anterior margin of prodorsum transverse, with median forked projection forming a central notch 15–25 [15]. No dorsal shields developed, with dorsal cuticle evidently smooth. Setae v2 and sc2 inserted in almost transverse line along anterior margin, slightly anterior to setae sc1. Dorsal setae of various forms, finely barbed. Setae sc2 and c3 extremely elongate, flagellate (broken on holotype; can be difficult to measure full length); setae sc1 small, obovate to weakly orbicular; setae around posterior margin e3, f3, h1, h2 narrowly lanceolate; setae v2, c1, d1, d3, e1 all small to minute. Setal measurements: v2 3–5 [3–4], sc1 10–12 [10–12], sc2 148–360 [178*], c1 6–7 [6–7], c3 144–318 [144*], d1 5–8 [5], d3 5–7 [7], e1 7 –9 [7–9], e3 37 –42 [-], f3 37–38 [37], h1 29–32 [29], h2 30–34 [-] (* = obviously broken).

Gnathosoma . Palp tarsus with solenidion 1, eupathidium 4 [4]; tibiogenu with 2 setae 7 [7], 9–14 [14].

Venter. ( Fig. 22 ) Ventral cuticle completely finely striate/plicate, with various patterns of fine striae/plicae. With oblique striae/plicae anterior to genital region; with transverse striae/plicae laterad genital region; with narrow band of longitudinal striae/plicae between g1–ps2. All setae short, fine, smooth to finely barbed, except setae 1a elongate, flagellate (difficult to measure full length). Setal measurements: 1a 54–81 [56–74], 1b 11–13 [-], 1c 13–14 [14], 2b 11–12 [11], 2c 9–13 [9–13], 3a 9–12 [9], 3b 10–12 [11–12], 4a 43–60 [43–60], 4b 8–9 [8–9], ag 10–11 [10–11], g1 6–7 [6–7], ps2 11–13 [11–12], ps3 10–13 [10].

Legs. ( Figs 23 , 24 ) Setal formulae for legs I – IV the same as the female except tr IV nude. Tarsi I and II each with one abaxial solenidion ωʺ (both 6–7) [both 6], companion seta ftʺ (both 6–7) [both 6–7], and one pair eupathidia p′ζ–pʺζ (all 5–6) [all 5–6]. Seta bvʺ on femur II much longer than on femur I; tarsi III–IV with setae tc′–tcʺ inserted on short projections.

Protonymph. Unknown.

Larva. (2 measured)

Dorsum. ( Fig. 25 ). Body measurements: v2–h1 140–158, sc2–sc2 75–88, c3–c3 88–101, f3–f3 49–51. Anterior margin of prodorsum broadly rounded, without projections or notch. Weak prodorsal shield evident, mostly smooth with finely granulate cuticle anteriorly. Dorsal cuticle laterad and posterad shield from setae sc2–e1–e3 with widely spaced, mostly transverse folds; region of smooth cuticle on lateral margin between setae c3–d3, with minute pore near d3; pygidial region of opisthosoma mostly smooth. Dorsal setae of various forms, finely barbed. Setae sc2 and c3 elongate, acicular not flagellate; setae h2 elongate, flagellate; setae e3, f3, h1 elongate, narrow lanceolate; setae v2, sc1, c1, d1, d3, e1 all minute. Setal measurements: v2 3, sc1 3–4, sc2 93–106, c1 3, c3 53–71, d1 3, d3 2–3, e1 2 –3, e3 37 –39, f3 27–29, h1 18–22, h2 53–62.

Gnathosoma . Palp tarsus with solenidion 1, eupathidium 3–4; tibiogenu with 2 setae 5, 6–8.

Venter. ( Fig. 26A ). Ventral cuticle completely finely striate/plicate, with mostly oblique striae/plicae. All setae fine, smooth. Setal measurements: 1a 34–37, 1b 8–9, 3a 7–8, ps2 5–7, ps3 5–6.

Legs. ( Fig. 26B ). Legs covered in finely granulate cuticle. Setal formulae for legs I – III: cx 1-0-0, tr 0-0-0, fe 3-3-2, ge 1-1-1, ti 5-5-3, ta 7(1)-7(1)-3. Tarsi I and II each with one abaxial solenidion ωʺ (5, 4–5, respectively), companion seta ftʺ (both 5), and one pair eupathidia p′ζ–pʺζ (all 4–5). Setae ft′ and ftʺ inserted on small tubercles.

Colour. Extenuipalpus quadrisetosus is described as rust red (i.e. immatures), while E. gibbus is described as ʺdirty whiteʺ in colour with lilac dorsal setae by Lawrence (1943).

Host. Cape quince, Cryptocarya woodii Engl. ( Lauraceae ).

Distribution. South Africa: KwaZulu-Natal.

Remarks. The holotype deutonymph is missing several structures, including the following leg characters—the entire leg I on the right-hand side, seta d on fe III of both legs, seta l′ on ge III of both legs, seta ft′ on ta III of both legs ( Fig. 23 ). The holotype is an early stage pharate, however the adult within is not developed enough to determine if it is a male or female. Although there are a few minor differences between the holotype and the two non-type deutonymphs, such as seta d on femora I–II appearing to be narrower ( Figs 23 , 24 ) and dorsal setae c1 and d1 being smaller on the holotype ( Fig. 20A ) than on the two non-types ( Fig. 20B ), these are assumed to represent natural variation as would be expected between individuals of immature stages.

Lawrence (1943) wrote that individuals of E. quadrisetosus can be found on both the upper and lower surfaces of the leaves of the host plant, though they are more usually on the upper surface. The mites appear to prefer the region along the midrib and were also found on the petiole. Although Lawrence described live E. quadrisetosus mites as rust-red in colour, he was talking about the immatures. Whereas the actual adult females are described as ʺdirty whiteʺ in colour with lilac dorsal seta. Lawrence goes on to note that the mites (i.e. immatures) move “more slowly than any other South African species of Tenuipalpus and that their “movements can be described as hardly perceptible”. Such slow movements are commonly observed for immatures of Tenuipalpus and related taxa.

Figures

FIGURE 13. Extenuipalpus quadrisetosus, adult female dorsum (paratype of E. gibbus).

FIGURE 14. Extenuipalpus quadrisetosus, adult female dorsum (paratype of E. gibbus). A—photographed using differential interference contrast (DIC), and B—phase contrast.

FIGURE 15. Extenuipalpus quadrisetosus, adult female venter (paratype of E. gibbus).

FIGURE 16. Extenuipalpus quadrisetosus, adult female (paratype of E. gibbus) legs I–IV (right side; dorsal aspect), with detail of ventral aspect of each tarsus.

FIGURE 17. Extenuipalpus quadrisetosus, adult male. A—detail of dorsum; B—detail of aedeagus (paratype of E gibbus).

FIGURE 18. Extenuipalpus quadrisetosus, adult male venter (paratype of E. gibbus).

FIGURE 19. Extenuipalpus quadrisetosus, adult male legs I–IV (right side; legs I–II in mostly dorsal aspect; legs III–IV curved towards anterior in mostly adaxial aspect), with dorsal and ventral detail of left side tarsus II, detail of ventral aspect of tarsus I, and detail of abaxial aspect of tarsi III and IV.

FIGURE 20. Extenuipalpus quadrisetosus, deutonymph dorsum. A—holotype; B—non-type specimen.

FIGURE 21. Extenuipalpus quadrisetosus, deutonymph flagellate setae from specimens in FIGURE 20, A—holotype; B—nontype specimen.

FIGURE 22. Extenuipalpus quadrisetosus, holotype deutonymph, detail of posterior venter.

FIGURE 23. Extenuipalpus quadrisetosus, holotype deutonymph, detail of legs I–IV (I–II left side, dorsal aspect; legs III–IV right side, dorsal aspect). Note that setae d on fe III, l′ on ge III and ft′ on ta III are missing on both legs III.

FIGURE 24. Extenuipalpus quadrisetosus, non-type deutonymph (as E. gibbus), details of legs I–IV.

FIGURE 25. Extenuipalpus quadrisetosus, larva paratype, detail of dorsum.

FIGURE 26. Extenuipalpus quadrisetosus, larva paratype, detail of venter and legs I–III. A—venter, B— legs I–III (right side; dorsal aspect).