Ameronothrus lineatus ( Thorell, 1871 )

Ermilov, Sergey G., Stary, Josef & Block, William, 2012, Morphology of juvenile instars of Ameronothridae (Acari: Oribatida), Zootaxa 3224 (1), pp. 1-40 : 10-24

Ameronothrus lineatus ( Thorell, 1871)

( Figs. 42–78 )

Dimensions. Length: larva 315–332 (n=2), protonymph 381–448 (n=3), deutonymph 498–531 (n=4), tritonymph 614–680 (n=5). Width: larva 182 (n=2), protonymph 215–249 (n=3), deutonymph 265–315 (n=4), tritonymph 381–431 (n=5).

Integument. General body cuticle weakly sclerotized, colorless to yellowish and yellow-brownish. Legs and gnathosoma sometimes more sclerotized, brownish in nymphs. Cuticle of prodorsum with one pair of diagonal folds in mid-lateral region. A horizontal folds between the diagonal folds are presented in nymphs. Cuticle of proximolateral region of prodorsum and of gastronotic, anogenital and sternal regions folded. Cuticle of lateral parts of epimeres smooth. Prodorsum proximally with three porose sclerites, medial larger than lateral pair; gastronotic region without sclerites.

Prodorsum ( Figs. 42 , 48–54 ). Relatively short, about 2/3 length of gastronotic region in lateral view. Rostrum broadly rounded in dorsal view. All prodorsal setae set on small tubercles. Rostral seta long, setiform, smooth. Lamellar and interlamellar setae spiniform, smooth or with one cilium. Exobothridial seta short, spiniform, smooth. Sensillus longer than diameter of bothridium, with developed stalk and oval, slightly barbed head. Relative length of prodorsal setae on all juvenile instars: ro> ss> in> le> ex. Prodorsal setae measurements of juvenile instars compared in Table 4.

Gastronotic region ( Figs. 42 , 48–49 , 55–56 ). Rounded posteriorly. Larva with 12 pairs and nymphs with 15 pairs of gastronotic setae. All setae set on small tubercles, approximately similar in length (only h 3 short in larva) spiniform, smooth or with one cilium. Cupules ia and im and ip not evident among folds of gastronotic region. Opisthonotal gland opening poorly visible.

See Table 1 for explanations.

Anogenital region ( Figs. 43 , 57–60 , 66–68 ). Ontogenetic formulae (larva to tritonymph, respectively): genital 0–1–3–5, aggenital 0–0–1–1, adanal 0–0–3–3, anal 0–0–0–2. All setae weakly spiniform (only genital setae with thin tips), smooth. Cupules ih, ips and iad appearing in normal ontogenetic pattern.

Epimeral region ( Figs. 43 , 61 , 69–71 ). Setal formulae for epimeres: larva 3–1–2 (third seta of first epimere forms protective scale over respective Claparède’s organ); protonymph 3–1–2–1; deutonymph and tritonymph 3–1–2–2. All setae short, spiniform and smooth.

Gnathosoma ( Figs. 72–74 ). All hypostomal setae (h, m, a) setiform and barbed; a and h longer than m. Lateral lips with 2 pairs thickened, barbed adoral setae (or 1, or 2). Palp setal formula 0–2–1–3–9+1ω. Palpal solenidion ω and eupathidium acm not forming double horn. Cheliceral setae setiform, barbed; cha longer than chb.

Legs ( Figs. 44–47 , 62–65 , 72–78 ). Ontogeny of leg setae and solenidia given in Tables 5 and 6. Leg IV of protonymph with formula 0–0–0–0–7. Setae smooth. Seta u thick, with numerous, small barbs in basal part and setiform, smooth in medio-distal part. Setae of pairs u, a, p, it and tc (sometimes also ft) with expanded, oval or rounded tip. Tibiae and genua with coupled solenidion and seta d. Famulus short, spiniform, inserted anterior to both solenidia. Solenidion φ 1 on tibia I long, setiform; other solenidia of medium size or short, weakly thickened, rod-like, blunt-ended.

See Table 3 for explanations; d σ and d φ — solenidion and seta coupled.

Halozetes crozetensis ( Richters, 1907) 1

( Figs. 79–117 )

Dimensions. Length: larva 298–332 (n=5), protonymph 381–398 (n=3), deutonymph 498–564 (n=3). Width: larva 132–149 (n=5), protonymph 199–215 (n=3), deutonymph 315–332 (n=3).

Integument. General body cuticle weakly sclerotized, colourless to yellowish and yellow-brownish. Legs and genital valves more sclerotized, brownish. Granular cerotegument covers body and legs in all juvenile instars; granules hemispherical, small (diameter up to 2 µm). Cuticle of prodorsum with several folds dorsally; one pair of parallel folds in mid-lateral part. Cuticle of proximolateral region of prodorsum and of gastronotic, anogenital and sternal regions folded. Cuticle of lateral parts of epimeres smooth. Gastronotic porose sclerites absent. Indistinct foveolae present postero-laterally in gastronotic and anogenital regions.

Prodorsum ( Figs. 79, 81 , 86–94 ). Relatively short, about half length of gastronotic region in lateral view. Rostrum broadly rounded in dorsal view. All prodorsal setae set on small tubercles. Rostral and lamellar setae weakly thickened, heavily barbed. Interlamellar seta longest on prodorsum, thickened, with strong barbs. Exobothridial seta shortest on prodorsum, spiniform, smooth or with one barb. Sensillus longer than diameter of bothridium, with developed stalk and oval head; latter smooth or with indistinct granules. Relative length of prodorsal setae on all juvenile instars: in> ss ≈ ro> le ≈ ex. Measurements of prodorsal setae of juvenile instars compared in Table 7.

Gastronotic region ( Figs. 79, 81 , 86–87 , 95–99 ). Rounded posteriorly. Larva with 12 pairs and nymphs with 15 pairs of gastronotic setae. All setae set on small tubercles. Setae h 1, h 2 in larva and h 1, h 2, h 3 in nymphs longer than others, heavily barbed; others setae short, thickened, with strong barbs. Cupules ia and im not evident among folds of gastronotic region; ip and opisthonotal gland opening poorly visible.

Anogenital region ( Figs. 80 , 100–103 , 108–109 ). Ontogenetic formulae (larva to deutonymph, respectively): genital 0–1–3, aggenital 0–0–1, adanal 0–0–3, anal 0–0–0. All setae short, spiniform, smooth. Cupules ih, ips and iad poorly visible (often cupules well visible only when located near paraproctal valves), appearing in normal ontogenetic pattern.

Epimeral region ( Figs. 80 , 104 , 110–111 ). Setal formulae for epimeres: larva 3–1–2 (third seta of first epimere forms protective scale over respective Claparède’s organ); protonymph 3–1–2–1; deutonymph 3–1–2–2 All setae similar in length, spiniform, smooth.

See Table 1 for explanations.

Gnathosoma ( Figs. 112–114 ). All hypostomal setae (h, m, a) setiform; a and h slightly barbed, longer than smooth m. Lateral lips with 2 pairs thickened, barbed adoral setae (or 1, or 2). Palp setal formula 0–2–1–3–9+1ω. Palpal solenidion ω and eupathidium acm connected, forming double horn. Cheliceral setae similar in length; cha thickened, heavily barbed, chb little shorter, setiform, barbed.

Legs ( Figs. 82–85 , 115–117 ). Ontogeny of leg setae and solenidia given in Tables 8 and 9. Leg IV of protonymph with formula 0–0–0–0–7. Many setae (except on tarsi) thickened, with few, strong barbs. Seta u thick, barbed in basal part and setiform, smooth in medio-distal part. Setal pairs u, a, p, it and tc with expanded, oval or rounded tips. Famulus short, spiniform. Solenidion φ 1 on tibia I long, setiform; other solenidia of medium size or short, weakly thickened, rod-like, blunt-ended.

See Table 3 for explanations.

Figures

FIGURES 42–43. Ameronothrus lineatus, larva: 42 — dorsal view, 43 — ventral view, legs (except trochanters) and gnathosoma not shown. Scale bars 100 µm.

FIGURES 44–47. Ameronothrus lineatus, legs (44–46) of larva and leg (47) of protonymph: 44 — leg I, without trochanter, right, antiaxial view, 45 — leg II, without trochanter, right, antiaxial view, 46 — leg III, without trochanter, left, paraxial view, 47 — leg IV, right, antiaxial view. Scale bars 20 µm.

FIGURES 48–49. Ameronothrus lineatus, nymphs: 48 — protonymph, dorsal view, 49 — tritonymph, dorsal view. Scale bar (48) 100 µm, scale bar (49) 200 µm.

FIGURES 50–65. Ameronothrus lineatus, setae of tritonymph: 50 — rostral seta, 51 — lamellar seta, 52 — interlamellar seta, 53 — sensillus, 54 — exobothridial seta, 55 — gastronotic seta c2, 56 — gastronotic seta c3, 57 — genital seta g5, 58 — aggenital seta, 59 — anal seta an2, 60 — adanal seta ad2, 61 — epimeral seta 3b, 62 — seta d and solenidion on genu I, 63 — famulus and basal parts of seta ft’’ and solenidia on leg tarsus I, 64 — seta u’ on leg tarsus I, 65 — distal part of seta tc’’ on leg tarsus I. Scale bar 10 µm.

FIGURES 66–71. Ameronothrus lineatus, anogenital (66–68) and epimeral (69–71) regions of nymphs: 66 — anogenital region of protonymph, 67 — anogenital region of deutonymph, 68 — anogenital region of tritonymph, 69 — epimeral region of protonymph, 70 — epimeral region of deutonymph, 71 — epimeral region of tritonymph. Scale bars (66, 69–70) 50 µm, scale bars (67–68, 71) 100 µm.

FIGURES 72–78. Ameronothrus lineatus, gnathosoma (72–74) and legs (75–78) of tritonymph: 72 — subcapitulum, left part, palp not shown, 73 — palp, 74 — chelicera, distal part, 75 — leg I, without trochanter, left, antiaxial view, 76 — leg II, without trochanter, left, antiaxial view, 77 — leg III, left, antiaxial view, 78 — leg IV, right, paraxial view. Scale bar (72–74) 20 µm, scale bar (75–78) 50 µm.

FIGURES 79–81. Halozetes crozetensis, larva: 79 — dorsal view, 80 — ventral view, legs (except trochanters) not shown, 81 — lateral view, gnathosoma and legs (except trochanters and femora I, III) not shown. Scale bars 100 µm.

FIGURES 82–85. Halozetes crozetensis, legs (82–84) of larva and leg (85) of protonymph: 82 — leg I, without trochanter, right, antiaxial view, 83 — leg II, without trochanter, right, antiaxial view, 84 — leg III, right, antiaxial view, 85 — leg IV, left, antiaxial view. Scale bars 20 µm.

FIGURES 86–87. Halozetes crozetensis, nymphs: 86 — protonymph, dorsal view, 87 — deutonymph, dorsal view. Scale bar (86) 100 µm, scale bar (87) 200 µm.

FIGURES 88–107. Halozetes crozetensis, setae of deutonymph: 88 — rostral seta, 89 — lamellar seta, 90 — lamellar seta, 91 — medio-distal part of interlamellar seta, 92 — sensillus, 93 — exobothridial seta, 94 — exobothridial seta, 95 — gastronotic seta c1, 96 — gastronotic seta lm, 97 — gastronotic seta h2, 98 — gastronotic seta p1, 99 — gastronotic seta p2, 100 — genital seta g1, 101 — aggenital seta, 102 — adanal seta ad3, 103 — adanal seta ad3, 104 — epimeral seta 4a, 105 — famulus and basal parts of seta ft’’ and solenidia on leg tarsus I, 106 — seta u’ on leg tarsus I, 107 — distal part of seta a’’ on leg tarsus I. Scale bar 10 µm.

FIGURES 108–111. Halozetes crozetensis, anogenital (108–109) and epimeral (110–111) regions of nymphs: 108 — anogenital region of protonymph, 109 — anogenital region of deutonymph, 110 — epimeral region of protonymph, 111 — epimeral region of deutonymph. Scale bars (108–109) 100 µm, scale bars (110–111) 50 µm.

FIGURES 112–117. Halozetes crozetensis, gnathosoma (112–114) and legs (115–117) of deutonymph: 112 — subcapitulum, left part, palp not shown, 113 — palp, 114 — chelicera, distal part, 115 — leg I, without trochanter, right, antiaxial view, 116 — leg III, right, antiaxial view, 117 — leg IV, right, antiaxial view. Scale bars (112, 114) 20 µm, scale bar (113) 10 µm, scale bar (115–117) 50 µm.