Gahniacarus gersonus, Beard, Jennifer J. & Ochoa, Ronald, 2011

Beard, Jennifer J. & Ochoa, Ronald, 2011, New flat mite genera (Acari: Trombidiformes: Tenuipalpidae) associated with Australian sedges (Cyperaceae), Zootaxa 2941, pp. 1-37 : 14-15

Gahniacarus gersonus sp. nov. Beard & Ochoa

( Figs 1 b, 9–11)

Types. Holotype. Ƥ. Australia, New South Wales, Mt Alexander Reserve, Mittagong, 34°27’26”S, 150°27’00”E, 24.iv.2005, ex. red-fruited saw sedge Gahnia sieberiana Kunth. (Cyperaceae) (BRI voucher # PIF30818), J.J. Beard (QM). Paratypes. Same data as holotype: 4 Ƥ (separate slides), 6 Ƥ (same slide), 2 Ƥ (same slide), 1 deutonymph, 1 protonymph (QM); 3 Ƥ, on separate slides (USNM).

Diagnosis. Adult female ( Figs 1 b, 9). As per genus, in addition to: setae sc1 inserted on weakly developed tubercles, elongate; setal pair c1-c1 inserted on tubercle; f2 and f3 tubercles separated; large tubercles (not bearing setae) present between sc1-c1, posterad c1. Dorsal opisthosomal setae e3, f2, f3 present.

Immatures ( Figs 10–11 ). Larva not known. Protonymph with posterior opisthosomal setae e3, f3, h1 minute and setae f2 similar to other dorsal setae. Deutonymph with posterior opisthosomal setae f3, h1 minute and setae d1, e3, f2 similar to other dorsal setae.

Remarks. Setae f2 and f3 are inserted on well separated tubercles in G. gersonus , whereas setae f2 and f3 are inserted on contiguous tubercles in Gahniacarus tuberculatus ; prodorsal setae sc1 are elongate and tapered in G. gersonus , whereas setae sc1 are similar in size to other dorsal setae in G. tuberculatus .

Adult female. (15 measured).

Dorsum. ( Figs 1 b, 9) Body measurements: v2 –h1 287 – 315, sc2–sc2 75 – 86, c3–c3 81 – 92, f3–f3 37 – 42. Dorsal cuticle variable, with some indication of a prodorsal shield: oblique plicae mesad setae sc2 and eyes; transverse plicae posterad prodorsal shield to level of c3; cuticle between c1–e2 mostly smooth with some oblique grooves and plicae associated with tubercles; longitudinal plicae present between f3–f3. Setae c1 inserted together on large single central tubercle; setae sc1, c3, d3, e3, f2 on large tubercles; single smooth tubercle present posterad c1. Setae sc1 obviously elongate, strongly barbed; h1 minute, barbed; h2 elongate, smooth with minute distal club; all other dorsal setae thick with dorsal surface strongly barbed, almost pubescent (especially basally) and ventral surface smooth: v2 37 – 43, sc1 171 – 215, sc2 32 – 38, c1 43 – 58, c 3 31 – 35, d1 45 – 53, d3 35 – 41, e3 33 – 40, f2 48 – 55, f 3 28 – 38, h1 3, h2 150 – 166.

Gnathosoma . ( Fig. 9 ) Gnathosoma elongate, as long as leg I. Dorsal cuticle with longitudinal plicae; ventral cuticle finely papillate anterad setae 1b. Ventral setae m absent. Palps with three segments; 0, 2, 0(2); tibia with two setae (d 13 – 16, v 10 – 13); tarsus with two eupathidia (5 – 6, 7 – 9). Cheliceral stylets 147 – 158.

Venter. Cuticle with fine, mostly transverse, plicae; plicae longitudinal on ventral gnathosoma to setae 1a; plicae transverse between 1a -ag, becoming thicker and more widely spaced laterally between leg II – III (similar to dorsal plicae); plicae on genital flap longitudinal laterally, arching anteriorly around g1; plicae longitudinal to oblique laterad genito-anal region. Setae g1 and g2 on genital flap. All ventral setae fine, smooth. Setal measurements: 1a 63* – 146, 1 b 64 – 84, 2 b 18 – 30, 2 c 15 – 22, 3 a 20 – 25, 3 b 13 – 21, 4 a1 49 – 77, 4 a2 48 – 80, 4 b 10 – 19, ag 18 – 20, g 1 18 – 25, g 2 16 – 24, ps 1 13 – 19, ps 2 10 – 15 (* = broken). Setae 1a, 1b, 4a1, 4a2 elongate, fine (difficult to consistently determine full length); setae 2b and 2c widely separated.

Spermatheca. ( Fig. 9 ) A long narrow tube from the genital opening (anterad seta ps2) terminates in a small blunt-tipped, narrow, cylindrical vesicle (10 – 11).

Legs. ( Fig. 9 ) Setal formula for legs I – IV: 1-1-3-0-5-7(1), 2-1-3-0-5-7(1), 1-1-2-0-3-3, 1-1-2-0-3-3 respectively. Tarsi I and II each with one antiaxial solenidion ω ” (5 – 7, 4 – 5 respectively) and two distal eupathidia p ζ ’- p ζ ” (7 – 8, 6 – 7; 6 – 8, 6 respectively); ta I – IV u’-u” asymmetrically barbed. Femur I with long, barbed dorsal seta (50 – 62). Tenent hairs increasing in length, shortest basally to longest distally.

Colour. This species is lemon green with small black spots internally (presumably food in the gut).

Adult male. Unknown.

Deutonymph. (1 measured).

Dorsum. ( Fig. 10 ) Body measurements: v2 –h1 258, sc2–sc2 78, c3–c3 82, f3–f3 43. Cuticle completely plicate, mostly transverse plicae, with some longitudinal plicae on prodorsum between v2 –sc1 and posteriorly between setae d1–h1. Setae f3, h1 minute; setae h2 elongate, smooth; all other setae thick, strongly barbed: v 2 23 – 24, sc1 52, sc 2 27 – 28, c1 23, c 3 25 – 27, d1 24, d 3 26 – 29, e 3 20 – 22, f 2 29 – 30, f3 3, h1 2, h2 91.

Gnathosoma . ( Fig. 10 ) Gnathosoma elongate, as long as leg I. Ventral setae m absent. Palps with three segments; formula 0, 2, 0(2); tibia with two setae (d 11, v 8); tarsus with two eupathidia (5, 8). Cheliceral stylets 119.

Venter. Cuticle completely plicate; longitudinal plicae on ventral gnathosoma to setae 1a, transverse plicae 1a– g1; oblique plicae laterad ps1–2 (anal region); lateral plicae between legs II – III stronger and more widely separated than medial plicae. Setal measurements: 1a 47* – 92, 1 b 32, 2 b 17 – 18, 2 c 14 – 15, 3 a 16, 3 b 11, 4 a 1 41, 4 b 8, ag 9, g1 7 – 8, ps1 6 – 7, ps2 4 (* = broken). Setae 4a2, g2 absent.

Legs. ( Fig. 10 ) Setal formulae for legs I – IV: 1-1-3-0-5-7(1), 2-1-3-0-5-7(1), 1-1-2-0-3-3, 1-0-2-0-3-3 respectively. Tarsis I and II each with one antiaxial solenidion ω ” (4, 3 respectively) and two distal eupathidia p ζ ’-p ζ ” (7, 6; 6, 6 respectively); ta I – IV u’-u” asymmetrically barbed. Femur I with long, barbed dorsal seta (31).

Protonymph. (1 measured).

Dorsum. ( Fig. 11 ) Body measurements: v2 –h1 202, sc2–sc2 72, c3–c3 77, f3–f3 31. Cuticle completely plicate, mostly transverse plicae, with some longitudinal plicae on prodorsum between setae v2 –sc1 and posteriorly between setae d1–h1. Setae e3, f3, h1 minute; h2 elongate with minute club; all other setae thick, strongly barbed: v 2 8 – 10, sc1 29, sc 2 21 – 22, c1 16, c 3 23 – 24, d 1 12 – 15, d 3 24 – 25, e3 3 – 5, f 2 18 – 19, f3 1 – 2, h1 1 – 2, h2 74.

Gnathosoma . ( Fig. 11 ) Gnathosoma almost as long as leg I. Band of oblique plicae ventro-lateral margins. Ventral setae m absent. Palps with three segments; formula 0, 2, 0(2); tibia with two setae (d 9 – 10, v 7 – 8); tarsus with two eupathidia (5, 7). Cheliceral stylets 93.

Venter. Cuticle completely plicate; plicae longitudinal gnathosoma to setae 1a, transverse 1a–ag, oblique laterad ps1–2. Setal measurements: 1a 42 – 48, 1 b 36 – 42, 2 c 9, 3a 11, 3 b 5, ag 3, ps1 3, ps2 3. Setae 2b, 4a1, 4a2, 4b, g1, g2 absent.

Legs. ( Fig. 11 ) Setal formulae for legs I – IV: 1-0-3-0-5-7(1), 1-0-3-0-5-7(1), 1-0-2-0-2-3, 0-0-2-0-3-3 respectively. Tarsus I and II each with one antiaxial solenidion (3, 2 – 3 respectively) and two distal eupathidia p ζ ’-p ζ ” (5, 5; 5, 4 respectively). Femur I with long, barbed dorsal seta (19).

Larva. Unknown.

Host. Red-fruited saw sedge, Gahnia sieberiana (Cyperaceae) , growing in open eucalypt forest along a watercourse, in clay soil.

Distribution. Mt Alexander Reserve, Mittagong, New South Wales, Australia.

Remarks. Individuals of this species wedge their bodies into the longitudinal grooves on the ventral surface of the leaf blades of the host plant. Once in the grooves, the adult mites extend their elongate anterior (sc1) and posterior setae (h2) out over the surface of the leaf blade. Numbers of mites were higher towards the tip of the leaf blades than near the base.

Etymology. This species is named for our colleague and fellow tenuipalpiphile, Uri Gerson.

Figures

FIGURE 1. DIC image of adult female dorsum. a. Gahniacarus tuberculatus sp. nov.; b. Gahniacarus gersonus sp. nov.; c. Cyperacarus naomae sp. nov. (scale bar = 50 μm).

FIGURE 9. Gahniacarus gersonus sp. nov. adult female—dorsum, with detail of legs; detail of spermatheca (scale bar = 25 μm).

FIGURE 10. Gahniacarus gersonus sp. nov. deutonymph—dorsum, with detail of legs.

FIGURE 11. Gahniacarus gersonus sp. nov. protonymph—dorsum, with details of legs.