Extenuipalpus niekerkae ( Meyer, 1979 )

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 : 8-19

Extenuipalpus niekerkae ( Meyer, 1979)

( Figs 1–12 )

Tenuipalpus niekerkae Meyer, 1979: 70 , figs. 299–308—original designation.

Extenuipalpus niekerkae ( Meyer, 1979) — Beard et al. 2016: 14.

Material examined. Paratypes: 1 female, 1 male, 1 deutonymph ex. spiny current Rhus longispina Eckl. & Zeyh. ( Anacardiaceae ) [currently Searsia longispina (Eckl. & Zeyh.) Moffett ], Addo Olifantpark (Addo Elephant National Park), Eastern Cape Province, South Africa, 13.ii.1974, L.C. Smit (5600; AcY: 77/916; ARC-PHP).

Diagnosis. Female. Prodorsal setae sc1 short, obovate, one third size of elongate oblanceolate setae sc2; mid-prodorsum with transverse folds. Opisthonotal setae c1, d1, e1 large, elongate obovate. Cuticle smooth or finely striate on coxal fields I–II. Ventral opisthosoma with small region of colliculate cuticle laterad anterior corners genital flap. 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 narrowly oblanceolate, twice size of short, oblanceolate setae sc1. Deutonymph. Setae sc2 elongate falcate; setae c3 orbicular; femur II seta d broadly lanceolate.

Description. Adult female. (1 measured). Dorsum. ( Figs 1 , 2 ). Body measurements: v2–h1 276, sc2–sc2 196, c3–c3 221, f3–f3 90. Anterior margin of prodorsum with median forked projection forming a central notch 28 and triangular projections extending between coxae I–II; median forked projection with small triangular projections midway along lateral margins. Prodorsal shield developed, with series of transverse folds centrally, flanked by series of weak oblique folds laterally. Setae v2 and sc2 inserted in almost transverse line anteriorly on shield, slightly anterior to setae sc1. Opisthosoma with shield developed centrally, with weak transverse wrinkles and folds; central shield region flanked by fine longitudinal striae/plicae laterally. Series of minute pores visible sublaterally on prodorsum, and pair minute pores visible medad c3–d3. Dorsal setae of various forms, finely barbed. Setae sc1 and d3 subequal in size, obovate, much smaller than other dorsal setae; setae v2 and e3 elongate narrow lanceolate; setae sc2 large, weakly falcate; setae c1, d1, e1 large, elongate obovate, inserted on small tubercles; setae c3, f3, h1, h2 ovate to broadly ovate. Setal measurements: v2 31–32, sc1 18–20, sc2 57–58, c1 59–60, c3 27–28, d1 59, d3 18–19, e1 49 –54, e3 43 –51, f3 44–47, h1 43–44, h2 45.

Gnathosoma . ( Fig. 3 ) Ventral cuticle posterad infracapitular setae m 12 with fine transverse striae/plicae. Palp tarsus with solenidion 1–2, eupathidium 6–7; tibiogenu with 2 setae 14, 16.

Venter. ( Fig. 3 ) Ventral cuticle mostly finely striate/plicate, appears smooth in regions with extremely weak fine striae. With fine longitudinal striae/plicae between setae 1b–1a and on coxae I–II (although appear smooth); broad band of finely striate cuticle between 1a–3a with lateral folds and wrinkles. Ventral opisthosoma with mostly smooth cuticle centrally, with fine oblique folds laterally; weak transverse striae/plicae on posterior genital flap; with fine longitudinal striae/plicae laterad genital region; with small region of colliculate cuticle laterad anterior corners of genital flap. All setae short, fine, smooth to finely barbed, except setae 1a elongate, flagellate (difficult to measure full length). Setae ag obscured by internal crystallisation. Setal measurements: 1a 141–183, 1b 22–25, 1c 20–21, 2b 26–30, 2c 20–23, 3a 14–15, 3b 23–25, 4a 12–14, 4b 21, ag not visible, g1 28, g2 17–19, ps2 22–25, ps3 30–32.

Spermathecal apparatus. Not visible.

Legs. ( Figs 4 , 5 ). Setal formulae as for the type species, E. quadrisetosus . Tarsi I and II each with one abaxial solenidion ωʺ (both 10–11), with companion seta ftʺ (both 7), and one pair of eupathidia p′ζ–pʺζ (all 8–9). Femora I–IV setae d thickened and heavily barbed; femora I–II seta l′ thickened and heavily barbed; seta bvʺ on femur II much thicker and more heavily barbed than on femur I.

Adult male. (1 measured). Dorsum. ( Figs 6A, C ). Body measurements: v2–h1 257, sc2–sc2 190, c3–c3 173, f3– f3 66. Anterior margin of prodorsum with broad median forked projection forming a central notch 23. Prodorsal and opisthosomal shields weakly developed. Prodorsum with finely wrinkled and folded cuticle, folds mostly transverse centrally and oblique laterally; one pair minute pores visible sublaterally. Dorsal opisthosoma weakly divided into mesonotal region and pygidial region by narrow band of weak transverse striae/plicae; mesonotum with band of folds forming broad U-shaped pattern between setal rows C and D; one pair minute pores visible mesad c3; pygidial region with series of folds forming weak arching pattern of mostly longitudinal striae/plicae; pair large pores visible laterally. Posterior margin of opisthosoma with short triangular projection extending between setae h1. Dorsal setae different in form to those of female and mostly smaller, finely barbed; dorsal barbs finer than ventral barbs ( Fig. 5c ). Most setae of subequal length, except setae sc1, d1 and e1 much shorter; anterior setae mostly elongate narrow obovate, becoming broadly lanceolate to ovate on posterior margin. Most dorsal setae inserted on small rounded tubercles. Setal measurements: v2 37–42, sc1 18–19, sc2 41–42, c1 28–31, c3 28–32, d1 12–13, d3 27–29, e1 11, e3 25 –27, f3 24–32, h1 28–30, h2 26.

Gnathosoma . ( Fig. 6B ). Ventral cuticle posterad infracapitular setae m 12–13 with fine transverse striae/plicae. Palp tarsus with solenidion 5–6, eupathidium 8–7; tibiogenu with 2 setae 12, 14.

Venter. ( Fig. 7A ). Ventral cuticle mostly smooth anteriorly and finely striate/plicate posteriorly, with various patterns of fine striae/plicae. Cuticle on coxa I–II smooth, with regions of fine punctations; band of cuticle between coxae I–II and sejugal furrow smooth centrally with fine longitudinal striae/plicae laterally. Cuticle on ventral opisthosoma with fine striae/plicae forming a broadly U-shaped pattern; with fine longitudinal striae/plicae on genital valves. 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 thickened tapering setae, inserted distally on tapered projection from genitoanal region ( Fig. 7A ). Setae g1, g2, ps2 inserted together in a row on paired flaps flanking genitoanal projection. Setal measurements: 1a 156–170, 1b 22, 1c 16–17, 2b 22–25, 2c 15–18, 3a 14–15, 3b 16–17, 4a 23–26, 4b 13–14, ag 9–12, g1 14–15, g2 16, ps2 26, ps3 24–25.

Aedeagus. ( Fig. 7B ). Sclerotised, extremely elongate, finely tapering (162), difficult to measure full length, with narrow membranous tube emerging basally, tube apparently ending in truncate bulb.

Legs. ( Figs 8 , 9 ). Setal formulae same as adult female except solenidion ω′ present on ta I–II. Tarsi I and II each with two solenidia (ta I adaxial ω′ 11–12, abaxial ωʺ 17–18; ta II adaxial ω′ 13, abaxial ωʺ 13–14), with distant companion seta ftʺ (both 6–7), and one pair distal eupathidia p′ζ–pʺζ present (all 9–10). Femora I–IV setae d thickened and heavily barbed; femora I–II seta l′ thickened and heavily barbed; seta bvʺ on femur II ( Fig. 8C ) much thicker and more heavily barbed than on femur I ( Fig. 8A ).

Deutonymph. (1 measured). Dorsum. ( Fig. 10 ). Body measurements: v2–h1 333, sc2–sc2 173, c3–c3 212, f3–f3 80. Anterior margin of prodorsum with median forked projection forming a central notch 27. Weakly developed prodorsal and pygidial shields evident, both smooth; shields separated by broad band of transversely folded membranous cuticle; small region of colliculate cuticle along anterior margin of pygidial shield; pair minute pores medad both setae c3 and d3. Setae v2, sc1 and sc2 inserted in almost transverse line along anterior margin of prodorsum. Posterior margin of opisthosoma with short, weakly triangular projection extending between setae h1. Dorsal setae of various forms, finely barbed. Setae v2 minute, lanceolate; setae sc1 and c1 small, orbicular; sc2 large, elongate falcate; c3 large, orbicular; setae d3 minute, oblanceolate; setae e3, f3, h1, h2 elongate weakly falcate-lanceolate; setae d1 and e1 missing. Setal measurements: v2 7–8, sc1 10, sc2 78–80, c1 12–13, c3 24x23– 25x22 (orbicular), d1 missing, d3 9–10, e1 missing, e3 47 –49, f3 45–46, h1 35, h2 43–46.

Gnathosoma . Palp tarsus with solenidion 1, eupathidium 4–5; tibiogenu with 2 setae 7–6, 9–10.

Venter. ( Fig. 11 ). Ventral cuticle completely finely striate/plicae, with various patterns of fine striae/plicae. Posterior venter with mostly transverse striae/plicae between setae 4a–ag, becoming curved towards ag; with transverse striae/plicae flanking genitoanal region; with narrow band of longitudinal striae/plicae medially between g1–ps2. All setae short, fine, smooth to finely barbed, except setae 1a and 4a elongate, flagellate (difficult to measure full length). Setal measurements: 1a 60–65, 1b 11–12, 1c 14–15, 2b 15–16, 2c 17–20, 3a 7–10, 3b 13–14, 4a 39, 4b 9–10, ag 10–12, g1 9–10, ps2 13–14, ps3 11–12.

Legs. ( Fig. 12 ). 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 (ta I 8; ta II 7), with distant companion seta ftʺ (both 4), and one pair of ventral eupathidia p′ζ–pʺζ present (ta I 7; ta II 6). Seta bvʺ on femur II much larger and longer than on femur I; setae d on femora I–IV and seta l′ on genu III large, broad lanceolate; tarsi III–IV with setae tc′–tcʺ inserted on short projections; seta ft′ on tarsi III–IV flagellate.

Hosts. Spiny currant Searsia longispina (Eckl. & Zeyh.) Moffett ( Anacardiaceae ) (formerly Rhus longispina Eckl. & Zeyh. ); white pear Apodytes dimitiata E.Mey. ex Arn. ( Icacinaceae ); baboon grape Rhoicissus digitata (L. F.) Gilg & M. Brandt ( Vitaceae ); sea guarrie Euclea racemosa L. ( Ebenaceae ); Karoo crossberry Grewia robusta Burch ( Malvaceae / Tiliaceae ).

Distribution. South Africa: Eastern Cape Province, KwaZulu-Natal.

Remarks. The description in Meyer (1993) has some errors which were noted in Beard et al. (2016) - tarsi I–II have 9(1) setae; femora III–IV have two setae (d, evʹ) in the adult and deutonymph, and the male has two solenidia on tarsi I–II.

Meyer (1993) describes E. nierkerae as being red in colour, but does not specify from which plant part the mites were collected.

Figures

FIGURE 1. Extenuipalpus niekerkae, adult female paratype dorsum (note that the left seta e3 appears narrow because it has twisted and is presented in a lateral aspect).

FIGURE 2. Extenuipalpus niekerkae, adult female paratype dorsum. A—photographed using differential interference contrast (DIC), and B—phase contrast.

FIGURE 3. Extenuipalpus niekerkae, adult female paratype venter (n. b., setae ag are obscured but are assumed to be present).

FIGURE 4. Extenuipalpus niekerkae, adult female paratype. A—leg I (right side), folded in half showing femur and genu in dorsal aspect and tibia and tarsus in abaxial aspect, with detail of adaxial aspect of tarsus I; B—tibia I (left side, dorsal aspect); C—leg II (right side; dorsal to abaxial aspect); D—detail of tarsus II (left side; abaxial and adaxial aspects).

FIGURE 5. Extenuipalpus niekerkae, adult female paratype, legs III and IV (right side; dorsal to abaxial aspect), with detail of tarsi III and IV (left side).

FIGURE 6. Extenuipalpus niekerkae, adult male paratype. A—detail of dorsum; B—detail of ventral infracapitulum, palps and seta m; C—detail of a posterior opisthosomal seta.

FIGURE 7. Extenuipalpus niekerkae, adult male paratype. A—detail of venter, including aedeagus internally; B—detail of aedeagus.

FIGURE 8. Extenuipalpus niekerkae, adult male paratype legs. A—leg I (right side; dorsal to adaxial aspect) with detail of tarsus I (abaxial aspect); B—detail of tarsus I (left side; adaxial and abaxial aspects); C—leg II (right side; dorsal to adaxial aspect) with detail of tarsus II (abaxial aspect); D—detail of tarsus II (left side; adaxial and abaxial aspects).

FIGURE 9. Extenuipalpus niekerkae, adult male paratype legs III and IV (right side; abaxial aspect) with detail of tarsus (ta III adaxial aspect; ta IV left side).

FIGURE 10. Extenuipalpus niekerkae, deutonymph paratype dorsum.

FIGURE 11. Extenuipalpus niekerkae, deutonymph paratype, detail of posterior venter.

FIGURE 12. Extenuipalpus niekerkae, deutonymph paratype legs I–IV (right side; leg I in dorsal to adaxial aspect; legs II–IV in dorsal aspect) with detail of tarsus I (left side; dorsal aspect).