Acaricis plana, Beard & Gerson, 2009

Beard, J. J. & Gerson, U., 2009, A new flat mite genus, Acaricis (Prostigmata: Tenuipalpidae), from Australian sedges (Cyperaceae), Zootaxa 2073 (2073), pp. 31-44 : 36-44

Acaricis plana sp. nov. Beard & Gerson

( Figs 6–13)

Types. Holotype. ♀. Australia, Queensland, 10 km NNW Murgon, Jack Smith Scrub Conservation Park, 26°09’17” S 151°54’35” E, 24.xii.2007, ex. native sedge Scleria sphacelata F. Muell. (Cyperaceae) , J.J. Beard, deposited in QM. Paratypes. 6 ♀, 6 ♂, 6 deutonymphs, 5 protonymphs, 4 larvae, same data as holotype (all on separate slides). (3 ♀, 3 ♂, 3 deutonymphs, 3 protonymphs, 2 larvae deposited in QM; 1 ♀, 1 ♂, 2 deutonymphs, protonymph, larva in ANIC; 1 ♀, 1 ♂ in DEFARI; 1 ♀, 1 ♂, deutonymph, protonymph, larva in USNM).

Female. Dorsum. ( Fig. 6) Body measurements: length between setae v2-h1 345–361, width between setae sc2-sc2 135–142, c3-c3 142–147, f2-f2 97–102. Dorsal cuticle relatively smooth; prodorsum mostly smooth with light transverse striae anterior to setal row C; light longitudinal striations laterad setae d1 to e1, these striae form u-shaped pattern posterad setae e1; pair of pores present anterolaterad e1. Dorsal cuticle appears thickened into an apparent shield; edge of shield is evident laterally by presence of transverse striae, especially obvious laterad setae e2, f2, f3, h1, h2. Elongate, forked rostral shield present (internal depth 25–36). Most dorsal setae short (<10 µm), smooth; setae sc2, f2, f3 and h1 thick, broadly lanceolate, barbed; setae h2 elongate, ending in minute club. Dorsal setae measurements: v2 5–6, sc1 6–8, sc2 17–22, c3 5–6, d1 7–8, d3 5–6, e1 6 –7, e3 6 –7, f2 19–23, f3 19–22, h1 19–23, h2 76–87.

Palpi. Palpi. (see Figs 6, 7) Palpi four segmented. Setal formula: 0, 0, 2, 2(2). Palpal tarsus with two eupathidia (4–7, 4–6).

Venter. ( Figs 7, 8A) Cuticle of podosomal venter with weak, fine transverse striae (difficult to see laterally); cuticle smooth between setae 1a and coxae I–II; fine striae become strong and coarse along lateral margin of body. Cuticle of opisthosomal venter with obvious transverse striae between setae 4a1 / 4a2 and g1; genital flap with few longitudinal folds; cuticle surrounding genito-anal region smooth. Setae g1 inserted anterior to setae g2 on genital flap ( Figs 7, 8A). Setae 1a, 4a1 and 4a2 elongate, fine (often difficult to determine full length), ending in minute clubs ( Fig. 7). Setal measurements: 1a 95–142, 1b 11–15, 1c 10–18, 2b 15–24, 2c 13–18, 3a 17–23, 3b 17–22, 4a1 86–113, 4a2 76–87, 4b 16–23, ag1 12–16, g1 12–19, g2 16–20, ps1 13–16, ps2 11–14.

Spermatheca. Spermatheca. (see Fig. 8A) A narrow, membranous duct runs from the genital opening to a sclerotised oval-shaped vesicle (6–8 µm).

Legs. ( Fig. 6) Setal formula for legs I–IV (coxae to tarsi): 2-1-4-2-5-8(1), 2-1-4-2-5-8(1), 1-1-2-1-3-5, 1- 0-2-0-3-5 respectively. Tarsi I and II each with one abaxial solenidion (ta I 7–9; ta II 6–9) and two eupathidia distally (ta I 6, 6–7; ta II 6, 6–7). Dorsolateral setae on tr III, fe I–III, ge I–III, ti I–IV lanceolate, finely barbed; ventral setae setiform, finely barbed; unguinal setae (u ’, u ”) strongly barbed; legs corrugate with strong transverse striae. Leg lengths: I 128–134, II 102–109, III 87–91, IV 88–92.

Colour. Body glossy with a translucent appearance, yellow-green with a longitudinal series of minute black spots laterally on either side of body; legs I–II obvious orange, legs III–IV pale orange; eyes red.

Male. Dorsum. ( Fig. 9) Body measurements: length between setae v2-h1 255–269, width between setae sc2-sc2 112–122, c3-c3 104–112, f2-f2 67–74, width at “waist” (level with coxae IV) 64–68. Dorsal cuticle almost entirely smooth with a few transverse striae at waist (level with coxae IV); prodorsum smooth with a few transverse striations anterior to setal row C; pair pores present laterally, posterad waist. Elongate, forked rostral shield present (24–27). Most dorsal setae short, smooth; setae sc2, f2, f3 and h1 broadly lanceolate, finely barbed; setae h1 elongate, ending in a minute club. Setal measurements: v2 5–7, sc1 5–7, sc2 12–19, c3 5–6, d1 6–7, d3 5–6, e1 5 –7, e3 4 –6, f2 14–19, f3 13–17, h1 13–17, h2 55–87.

Palpi. (see Figs 9, 10) Palpi four segmented. Setal formula: 0, 0, 2, 2(2). Palp tarsus with two eupathidia (4–5, 4–5).

Venter. ( Figs 10, 8B) Cuticle on ventral propodosoma with fine, mostly transverse striae (difficult to distinguish laterally); cuticle smooth between setae 1a and coxae I–II. Cuticle on ventral opisthosoma smooth with a band of strong, coarse, transverse striae at waist (between coxae IV); often with a few transverse striae immediately anterior to genito-anal region. Setae 1a and 4a1 elongate, ending in minute clubs. Setal measurements: 1a 68–115, 1b 11–15, 1c 9–12, 2b 12–19, 2c 16–18, 3a 13–18, 3b 12–18, 4a1 58–99, 4a2 15–28, 4b 13–18, ag1 12–15, g1 15–18, g2 16–26, ps1 10–12, ps2 6–8.

Aedeagus. (see Figs 8B, 9) A narrow, elongate, sclerotised aedeagus (49–52) tapering to a point posteriorly (at genital opening); membranous duct runs from sclerotised aedeagus to flared, lightly sclerotised, cone-shaped cup (11–13 wide, 6–8 deep) distally, appears to open into soft membranous vesicle.

Legs. ( Fig. 9) Setal formula for legs I–IV (coxae to tarsi): 2-1-4-2-5-9(2), 2-1-4-2-5-9(2), 1-1-2-1-3-6(1), 1-0-2-0-3-6(1) respectively. Tarsus I and II each with two solenidia (one adaxial, one abaxial) (ta I 10–12, 8–10; ta II 10–11, 8–9 respectively) and two eupathidia (ta I 6–7, 7–8; ta II 6–7, 6–7); tarsus III and IV each with one abaxial solenidion (ta III 9–11, ta IV 9–11). Dorsolateral setae on tr III, fe I–III, ge I–III, ti I–IV lanceolate, finely barbed; ventral setae setiform, finely barbed; unguinal setae (u ’, u ”) strongly barbed. Legs corrugate with strong transverse striae; leg lengths: I 124–127, II 97–100, III 85–87, IV 86–91.

Colour. Body yellow to orange, with a longitudinal series of minute black spots laterally on either side of body; legs orange.

Deutonymph. Dorsum. ( Fig. 11) Body measurements: length between setae v2-h1 270–299, width between setae sc2-sc2 111–131, c3-c3 95–122, f2-f2 66–87. Dorsal cuticle almost entirely smooth, with only a few transverse striations anterior to level of leg III. Evidence of a dorsal shield present as a thin sclerotised ridge running laterally along body margins from leg II to leg III; pair pores present anterolaterad e1. Elongate, forked rostral shield present (internal depth 18–26). Most dorsal setae short (<10 µm), smooth; setae sc2, f2, f3 and h1 lanceolate, lightly barbed; setae h2 elongate, ending in minute club. Dorsal setae measurements: v2 4–5, sc1 5–6, sc2 11–18, c3 4–5, d1 5–7, d3 3–5, e1 4 –6, e3 4 –5, f2 11–18, f3 10–17, h1 11–17, h2 51–82.

Palpi. Palpi. (see Fig. 11) Palpi four segmented. Setal formula: 0, 0, 2, 2(2). Palpal tarsus with two eupathidia (3–4).

Venter. Cuticle covered with fine, mostly transverse striae, except smooth area between setae 1a and coxae I–II. Setae 1a elongate, fine, ending in minute club (often difficult to determine full length). Setal measurements: 1a 63–123, 1b 10–16, 1c 10–11, 2b 10–16, 2c 12–16, 3a 11–14, 3b 11–15, 4a1 43–82, 4b 11–12, ag1 9–14, g1 10–13, ps1 7–11, ps2 7–9. Setae 4a2, g2 absent.

Legs. ( Fig. 11) Setal formula for legs I–IV (coxae to tarsi): 2-1-4-2-5-8(1), 2-1-4-2-5-8(1), 1-1-2-1-3-5, 1- 0-2-0-3-5 respectively. Tarsi I and II each with one abaxial solenidion (ta I 6–5; ta II 5–6) and two eupathidia distally (ta I 6, 6; ta II 5, 6). Dorsolateral setae on tr III, fe I–III, ge I–III, ti I–IV lanceolate, finely barbed; ventral setae setiform, finely barbed; unguinal setae (u ’, u ”) strongly barbed. Legs corrugate with transverse striae; leg lengths: I 93–106, II 76–85, III 58–71, IV 54–67.

Colour. Body dark orange to red, or yellow to green like female; legs I–II dark orange to red, legs III–IV paler.

Protonymph. Dorsum. ( Fig. 12A) Body measurements: length between setae v2-h1 187–260, width between setae sc2-sc2 94–111, c3-c3 86–94, f2-f2 54–58. Dorsal cuticle smooth anteriorly and posteriorly, with a broad band of transverse striations or folds mesally, anterior to level of leg III; these folds appear to allow the body to expand or lengthen. Evidence of dorsal shield present on opisthosoma as ridge running around caudal body margin laterad setae e3, f2, f3, h1, h2. Elongate, forked rostral shield present (internal depth 16–20). Most dorsal setae short (<10 µm), smooth; setae sc2, f2, f3 and h1 thick, barbed; setae h2 elongate, ending in minute club. Dorsal setae measurements: v2 3–4, sc1 4–5, sc2 8–11, c3 3–4, d1 5–6, d3 4–5, e1 4 –5, e3 3 –4, f2 8–11, f3 8–11, h1 10–12, h2 63–68.

Palpi. (see Fig. 12A) Palpi four segmented. Setal formula: 0, 0, 2, 2(2). Palpal tarsus with two eupathidia (3– 4, 3–4).

Venter. ( Fig. 12B) Cuticle with transverse striae; some weak longitudinal striae laterad genital area. Setae 1a elongate, fine, ending in minute club (often difficult to determine full length). Setal measurements: 1a 50–120, 1b 7–13, 1c 8–11, 2c 11–14, 3a 11–14, 3b 8–12, ag1 7–10, ps1 5–8, ps2 5–7. Setae 2b, 4b, 4a1, 4a2, g1 and g2 absent.

Legs. ( Fig. 12A) Setal formula for legs I–IV (coxae to tarsi): 2-0-3-1-5-8(1), 1-0-3-1-5-8(1), 1-1-2-1-3-5, 0-0-2-0-3-3 respectively. Tarsi I and II each with one abaxial solenidion (taI 4; ta II 4–5) and two eupathidia distally (ta I 4–6, 5–6; ta II 3–5, 4–5). Dorsolateral setae on tr III, fe I–III, ge I–III, ti I–III thicker than other leg setae, finely barbed; ventral setae setiform, finely barbed; unguinal setae (u ’, u ”) strongly barbed. Legs corrugate with strong transverse striae; leg lengths: I 70–73, II 57–61, III 50–53, IV 44–48.

Colour. Body dark orange to red, or yellow to green like female; legs I–II dark orange to red, legs III–IV paler.

Larva. Dorsum. ( Fig. 13A) Body measurements: length between setae v2-h1 175–197, width between setae sc2-sc2 83–91, c3-c3 72–78, f2-f2 41–45. Dorsal cuticle smooth anteriorly and posteriorly, with weak transverse striations from just posterior to sc2 to level of leg III; prodorsum with light striae forming u-shape medially. Rostral shield reduced to short, triangular projection anteromedially. Most dorsal setae short (<10 µm), smooth; setae sc2, f2, f3 and h1, thick, barbed; setae h2 elongate, ending in minute club. Dorsal setae measurements: v2 3–4, sc1 4–6, sc2 7–10, c3 3–4, d1 5–6, d3 3–4, e1 4 –5, e3 3 –4, f2 6–8, f3 7–8, h1 7–9, h2 67–76.

Palpi. ( Fig. 13A) Palpi four segmented. Setal formula: 0, 0, 2, 2(2). Palp tarsus with two eupathidia (3–4, 2).

Venter. ( Fig. 13B) Cuticle almost completely striate, covered with mostly transverse striae; striae longitudinal anterior to setae 1a and surrounding anal region. Setae 1a elongate, fine, ending in minute club (often difficult to determine full length). Setal measurements: 1a 55–89, 1b 10–12, 3a 9–13, ps1 5–7, ps2 4–7. Setae 1c, 2b, 2c 3b, 4b, 4a1, 4a2, ag1, g1 and g2 absent.

Legs. ( Fig. 13A) Setal formula for legs I–III (coxae to tarsi): 1-0-3-1-5-6(1), 1-0-3-1-5-6(1), 0-0-2-1-3-3 respectively. Tarsi I and II each with one abaxial solenidion (ta I 3–4; ta II 3–4) and two eupathidia distally (ta

I 5, 5–6; ta II 5, 5–6). Dorsolateral setae on fe I–II, ge I–II, ti I–II thicker than other leg setae. Leg lengths: I 57–60, II 51–54, III 48–49.

Colour. Body dark orange to red, or yellow to green like female; legs I–II dark orange to red, legs III–IV paler.

Host. Scleria sphacelata (Cyperaceae) .

Distribution. AUSTRALIA: Queensland: Murgon.

Remarks. See remarks section for A. danutae . The surface of the leaf blade of the host plant S. sphacelata is smooth and the mites were found flat against the underside of leaf blades. Eggs are dorsoventrally flattened, orange in colour and are most commonly laid on the ventral surface of the leaf blade along the midrib; however, many hatched eggs and caste skins were also present on the dorsal surface, especially in the central groove formed by the midrib.

Etymology. The name plana is feminine latin meaning “flat or even” and refers to the body of the mite and also the surface of the host plant’s leaves.