A new tribe of tarsonemid mites (Trombidiformes: Heterostigmatina) parasitic on tetrigid grasshoppers (Orthoptera) Author Seeman, Owen D. Author Lindquist, Evert E. Author Husband, Robert W. text Zootaxa 2018 4418 1 1 54 journal article 30134 10.11646/zootaxa.4418.1.1 7c4a5df1-45ab-459e-a37b-de55c5751d3b 1175-5326 1242435 A63167F9-4B7E-4CC2-A409-8F11DF7C9D95 Podotarsonemus australiensis Seeman, Lindquist & Husband sp. nov. Figures 1–6 Type material. Holotype. Adult female. AUSTRALIA , Spear Creek, Mt Molloy, Far North Queensland, 22 Jun 1975 , G.B. Monteith, ex Loxilobus sp. ( Tetrigidae ) ( Fig. 29A ). In QM. Paratypes . 7 females , 1 male , 2 larvae , same data as holotype . All in QM except 1 female in each of CNCI and UMMZ. Non-type material. 1 female, PAPUA NEW GUINEA , Upper Gusap River, near Butemu, Madang Dist., Oct 1965 , R. Pullen, 3500 ′ alt., ex Scelimena erimeta (Günther) (Tetrigidae) . In QM. Diagnosis. Female and male: Palps with 1 seta; chelicerae with 2 teeth; prodorsal plate entirely punctate; femur I with rudimentary setae lʹ and d ; femur II with tiny seta d , lacking lʹ and v″ ; genua II–III with 3 setae; tarsi II–III with 5 setae, seta uʹʹ present; trochanter IV with seta. Female: Setae sc1 absent; vestigial setae v2 expressed as anterolateral invaginations; coxisternal plates III–IV separated medially by longitudinal striae; setae h attenuate, 40–51 long; femorogenu IV with 2 setae; tracheal atria separate, post-atrial sac lightly sclerotized, not punctate. Male: Genital capsule without copulatory flanges; setae h2 developed, length 4–6; femorogenu IV with 1 seta; tibia IV with solenidion and attenuate seta; tarsus IV terminal, bearing 3 setae and claw. Male and larva: Leg I with tibia and tarsus I separate. Larva: Setae h1-2 , ps2 attenuate, setae ps1 short; leg I with 2 small claws. Description. ADULT FEMALE ( Figures 1–2 , 5A, B, n = 8 measured) Gnathosoma . Length 63–69, width 58–80. Palps 10–12, with 1 seta (2 long). Cheliceral stylets 25–27, with 2 teeth. Pharynx length 30–33, width 17. Dorsal setae ch 30–35, ventral setae su 6–14, palpcoxal setae e 7–13. Idiosoma . Length 255–310, width 165–197. Tracheal atria separate, post-atrial sac lightly sclerotized, not punctate, terminal tracheae not visible. Prodorsal plate with punctate sculpturing, 102–104 long, 130–140 wide; with 2 pairs of setae: v1 22 –25, thickened, tapering, with barbs, sc2 66–75 and vestigial v2 expressed as anterolateral invaginations. Distance between setae v1-v1 55 –60, v2-v2 62 –70, sc2-sc2 72– 80, v1 -sc2 34. Plates C, D, EF and H with punctate sculpturing, plate H heavily so. Setae c1, d, e, f tapering, with small barbs, c 1 19–27, c2 54–64, d 21–27, e 20–24, f 24–28. Distance between setae c1-c1 97–110, c2-c2 148–165, c1-c 2 22–25, d-d 78–87, e-e 83–87, f-f 35–44. Setae h tapering, 50–51. Distance between setae h-h 25–31. Cupules ia present, tiny, im absent, ih present. Setae ps attenuate> 250, distance between setae ps-ps 12–14. Coxisternal setae short to attenuate, 1a 11–12, 2a > 140, 3a > 230, 3b > 150. Distance between setae 1a-1a 17–20, 2a-2a 42–46, 3a-3a 10– 12, 3b-3b 14–24; alveolar vestiges of setae 1b, 2b barely discernible. Coxisternal plates III–IV separated by longitudinal striae; coxisternal plates III convex anteriorly, overlapping posterior margin of coxisterna II. Legs. Leg lengths: I 56 –62, II 62 –66, III 45 –49. Leg IV Fe-Ge length 29–32, Ti-Ta length 14–16. Leg III, femur and genu fused. Femur I, lʹ , d rudimentary, lʹʹ 1–2, vʹʹ 10–14; genu I lʹ 2–3, lʹʹ 2–3, vʹ 2–4, vʹʹ 3–4; tibia and tarsus I fused, tibial setae d 30–35, lʹ 4–6, lʹʹ 4–5, vʹ 8–10, vʹʹ 4–7, solenidion φ 3; tarsal setae tcʹ 14–15, tcʹʹ 12–14, pvʹ 7–10, pvʹʹ 6–7, s spine-like, 8–9, solenidion ω 7. Femur II d 1–2; genu II lʹ 3–4, lʹʹ 4–5, vʹ 3–5; tibia II d 20–22, lʹ 7–8, vʹ 15–16, vʹʹ 15–18; tarsus II pvʹ 12–16, tcʹ 12–15, tcʹʹ 17–21, uʹ spine-like, 8–10, uʹʹ 3–5, solenidion ω 6–7. Genu III lʹ 3–4, lʹʹ 5, vʹ 3–4; Tibia III d 14–15, lʹ 17, vʹ 7–8, vʹʹ 14–16; tarsus III pvʹ 12–16, tcʹ 16–18, tcʹʹ 18, uʹ spine-like, 8, uʹʹ 2–3. Trochanter IV with ventral seta vʹ 10–12; femorogenu IV with proximal femoral seta vʹ 5–6, distal genual seta vʹ 18–23; tibiotarsus with attenuate ventral tibial seta vʹ > 100 and terminal tarsal seta tc″ > 350. ADULT MALE ( Figs 3–4 , 5C, n = 1) Gnathosoma . Length 48, width 54. Palps 8. Cheliceral stylets 19, with 2 teeth. Pharynx length 28, width 14. Dorsal setae 20, ventral setae 5, palpcoxal setae 5. Idiosoma . Length 200, width 160. Prodorsal plate punctate, 82 long, 110 wide; with 3 pairs of setae ( v1 24 , sc1 12, sc2 55) and vestigial v2 expressed as anterolateral invaginations. Distance between setae v1-v1 37 , v2–v2 48 , sc1-sc1 70, sc2-sc2 69, v1 -sc2 50. Plate CD punctate. Setae c1 tapering, with small barbs, 24, c2 fine, 44, d with small barbs, 27 (asymmetrical, extra d expressed on right hand side); setae c 1 in nearly transverse alignment with c2 . Plate EF punctate, e 17, f 24, with small barbs. Distance between setae c1-c1 88, c2-c2 144, c1-c2 27, d-d 63, e- e 34, f-f 25. Cupules ia , im , ih indiscernible or absent. Genital capsule 47 long, 38 wide, bearing setae h1 6 long and alveolar remnants of h2 ; ventral flanges absent. Coxisternal setae short to attenuate 1a 14, 2a > 60, 3a> 80, 3b > 10 (broken). Distance between setae 1a-1a 20, 2a-2a 34, 3a-3a 8, 3b-3b 38; alveolar vestiges of setae 1b, 2b indiscernible or absent; setae 1a just posterior to ap1, setae 2a far posterior to ap2. Apodemes: ap2 almost reaching medially obsolete ap sj; ap5 well developed, fused, extending 45–50 anteriorly from base. Legs. Leg lengths: I 55 , II 58 , III 54 , IV 45 –51. Leg III, femur and genu separate. Femur I, lʹ , d rudimentary, lʹʹ 2, vʹʹ 10; genu I lʹ 3, lʹʹ 3, vʹ 3, vʹʹ 4; tibia and tarsus I separate, tibial setae d 28, lʹ 6, lʹʹ 5, vʹ 5, vʹʹ 11, solenidion φ 3; tarsal setae ftʹ 8, ftʹʹ 8, tcʹ 14, tcʹʹ 14, pvʹ 10, pvʹʹ 8, s spine-like, 8, solenidion ω 7. Femur II d 2; genu II lʹ 4, lʹʹ 6, vʹ 3; tibia II d 14, lʹ 15, vʹ 7, vʹʹ 20; tarsus II pvʹ 10, tcʹ 15, tcʹʹ 20, uʹ spine-like, 9, uʹʹ 6, solenidion ω 10. FIGURE 1. Podotarsonemus australiensis sp. nov. female. (A) dorsum; (B) leg IV; (C) respiratory system; st = stigmata, at = atrium, pa = post-atrial chamber. FIGURE 2. Podotarsonemus australiensis sp. nov. female, venter. FIGURE 3. Podotarsonemus australiensis sp. nov. male, dorsum; asymmetry shown for tergital seta d is peculiar to specimen illustrated. FIGURE 4. Podotarsonemus australiensis sp. nov. male, venter. FIGURE 5. Podotarsonemus australiensis sp. nov. (A) female, tibiotarsus I; (B) female, tarsus II; (C) male, tibia and tarsus I. Genu III lʹ 3, lʹʹ 5, vʹ 5; tibia III d 19, lʹ 18, vʹ 8, vʹʹ 13; tarsus III pvʹ 13, tcʹ 18, tcʹʹ 20, uʹ spine-like, 9, uʹʹ 1. Trochanter IV with ventral seta 7 long; femorogenu IV with proximal seta 2; tibia IV with solenidion φ 17 and ventral seta attenuate,> 120; tarsus IV terminal, with uʹ 4, tcʹʹ 2, pvʹʹ rudimentary, and claw 3. LARVA ( Fig. 6 , n = 2) Gnathosoma . Length 58–50, width 43–56. Palps 10–11. Cheliceral stylets 24–25, with 2 teeth. Pharynx length 26–30, width 14–15. Dorsal setae 7–10, ventral setae 4–5. Idiosoma . Length 255–350, width 142–225. Prodorsal plate smooth, 70–76 long, 111–125 wide; with 3 pairs of tapering, weakly barbed setae ( v1 10 , sc1 8–9, sc 2 20–21) and vestigial v2 . Distance between setae v1-v1 35 , v2-v2 56 , sc1-sc1 77–79, sc2-sc2 68– 70, v1 -sc2 24. Plates C, D, EF punctate. Setae tapering, barbed, c 1 15–17, c 2 13–15, d 16–18, e 16, f 20–21. Distance between setae c1-c1 76, c2-c2 127, c1-c 2 30–33, d-d 50–52, e-e 50–53, f-f 23–26. Plate H punctate, setae h1 attenuate,> 160, h2 ventral, attenuate, > 200. Distance between setae h1 24. Cupules ia , im present, ih indiscernible or absent. Setae ps1 fine, 10, ps2 attenuate 35–55. Coxisternal setae 1a 5–10, 2a 35–40, 3a attenuate,> 160, 3b 39. Distance between setae 1a-1a 17–21, 2a-2a 45, 3a-3a 32, 3b-3b 39; alveolar vestiges of setae 1b, 2b present. Legs. Femur I d , lʹ , lʹʹ rudimentary, vʹʹ 6–8; genu I lʹ rudimentary, lʹʹ 1, vʹ rudimentary, vʹʹ 1; tibia and tarsus I separate, tibial setae d 10–12, lʹ 3–5, lʹʹ 3, vʹ 3–4, vʹʹ 7–10, solenidion φ 3, tarsal setae tcʹ 11–13, tcʹʹ 10–12, pvʹ 5, pvʹʹ 3–5, s spine-like, 5, solenidion ω 5–6. Femur II d rudimentary; tibia II d 7–9, lʹ 4–5, vʹ 12, vʹʹ 8–11; tarsus II tcʹ 10, tcʹʹ 11, pʹ 1, uʹ spine-like, 6, uʹʹ 1– 2, solenidion ω 4–5. Tibia III d 7–8, lʹ 4–5, vʹ 9–12, vʹʹ 10–12; tarsus III pvʹ 11, tcʹ 10–14, tcʹʹ 6, pʹ 1–2, uʹ spine-like, 6–7, uʹʹ 1. Leg I with 2 small claws. Etymology. The species name australiensis refers to the name of the country where the type specimens were collected. Remarks. Podotarsonemus can be divided into two species groups. The first group ( australiensis species group, including P. australiensis , P. indicus and P. zuluensis ) all retains seta vʹ on trochanter IV, has females with longitudinal striae between coxisterna III–IV and setae h not attenuated, and males that retain at least a rudimentary tarsus on leg IV. In contrast, females of the second group ( boliviensis species group, including P. boliviensis , P. ecuadorensis , P. nipponicus , P. queenslandensis ) have lost seta vʹ on trochanter IV, have no longitudinal striae between coxisterna III–IV, have attenuate setae h , and males lack tarsus IV. The australiensis species group is possibly artificial because it is based on putative plesiomorphies. Of all its members, P. australiensis is perhaps the most plesiotypic species. In addition to the abovementioned features of the australiensis species group, P. australiensis is the only species that retains setae on genua II–III and has males with a divided tibia and tarsus I, tarsal structures on leg IV and a well-developed h seta. Despite these plesiomorphic attributes, P. australiensis also has the apomorphic loss of setae sc1 on the adult female, which is shared with P. queenslandensis and P. zuluensis . This feature is probably a homoplasious loss, as both these species belong in separate species groups. Another apomorphic loss is seta lʹ on femur II (absent in all species except P. boliviensis and P. ecuadorensis ) and the loss of seta v″ on femur II, which is autapomorphic in the Acarapinae . FIGURE 6. Podotarsonemus australiensis sp. nov. larva, dorsum. Exceptionally for the Tarsonemidae , the setae on genua II–III are absent in the larva but present in the adult. The delay in expression of these setae is an example of in-process evolutionary ontogenetic suppression, and while unusual in the Tarsonemidae , such ontogenetic delays are often reported for leg setae in other major taxa (e.g., see Beard et al. (2014) on the Tenuipalpidae ). Curiously, considerable leg setal reductions also occur in the larvae of species of Acarapis , which retain just one tibial and two tarsal setae. However, adults of all three species retain a near-fully developed leg chaetome for the Acarapinae ; hence the ontogenetic suppression of these setae is not connected with evolutionary trends towards simplification of leg setae. Instead, larvae of Acarapis show reductions in their gross leg morphology, suggesting their reductive trend is closely related to the apparent immobility of their larval stage. The material examined includes one non-type female from Papua New Guinea that we have included under P. australiensis . The specimen matches the Australian specimens reasonably well but is in poor condition, lacking setae sc2, c1, c2, d and e . However, many of its leg setae are longer, such as femur I d (2 versus rudimentary), and tibia I d (45 versus 30–35) and v″ (24 versus 4–7). Its host genus is also different: although both are Scelimeninae , Scelimena belongs to the Scelimenini while Loxilobus belongs to the Criotettigini . The differences in leg setal lengths and different host tribes suggest that this mite may be a different species, but more collections are required to test this hypothesis.