Pseudantarcticola georgiae ( Wallwork, 1970 )

Ermilov, Sergey G., Stary, Josef & Block, William, 2012, Morphology of juvenile instars of Ameronothridae (Acari: Oribatida), Zootaxa 3224 (1), pp. 1-40 : 24-30

Pseudantarcticola georgiae ( Wallwork, 1970)

( Figs. 118–156 )

Dimensions. Length: larva 249–265 (n=7), protonymph 348–365 (n=3), deutonymph 448–465 (n=3), tritonymph 547–614 (n=6). Width: larva 116–132 (n=7), protonymph 157–166 (n=3), deutonymph 215–232 (n=3), tritonymph 282–315 (n=6).

Integument. General body cuticle weakly sclerotized, colourless to yellow-grey. 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 longitudinal pair in mid-lateral region; one arch-like fold in mid-posterior region; one transverse fold between bothridia. Cuticle of proximolateral region of prodorsum and of gastronotic, anogenital and sternal regions folded. Cuticle of gastronotic region with folds. Cuticle of lateral parts of epimeres smooth.

Prodorsum ( Figs. 118, 120 , 128–134 ). 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 seta thin and smooth basally and thickened, strongly barbed in medio-distal part. Lamellar and exobothridial setae shortest on prodorsum, thin and slightly barbed (often with one barb). Interlamellar seta longest on prodorsum, thickened, with strong barbs. Insertion of interlamellar seta near each other and removed from bothridium. Sensillus longer than diameter of bothridium, with developed stalk and oval, slightly barbed head. Relative length of prodorsal setae on all juvenile instars: in> ss> (or ≈ sometimes in nymphs) ro> le ≈ ex. Measurements of prodorsal setae of juvenile instars compared in Table 10.

Gastronotic region ( Figs. 118, 120 , 128–129 , 135–136 ). More or less flattened in lateral view. Rounded posteriorly, sometimes with indistinct concave in larva and very broadly caudal lobe-shaped ledge. Larva with 12 pairs and nymphs with 15 pairs of gastronotic setae. All setae set on small tubercles, very short, similar in shape, spiniform, with one small barb or smooth (exception h 2 in larva: longer, setiform, barbed). Cupules ia, im and ip not evident among folds of gastronotic region; opisthonotal gland opening poorly visible.

Anogenital region ( Figs. 119 , 137–140 , 147–149 ). Ontogenetic formulae (larva to tritonymph, respectively): genital 0–1–3–5, aggenital 0–0–1–2, adanal 0–0–3–3, anal 0–0–0–2. All setae short, spiniform; genital setae smooth, others barbed. Cupules ih, ips and iad appearing in normal ontogenetic pattern.

See Table 1 for explanations.

Epimeral region ( Figs. 119 , 141–143 , 150–152 ). 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, tritonymph 3–1–2–3. All setae short, spiniform, with one barb or smooth (exceptions: 1b long and slightly barbed and 4c strongly barbed unilaterally).

Gnathosoma ( Figs. 121–123 ). All hypostomal setae (h, m, a) setiform and smooth; a and h longer than m. Lateral lips with 2 pairs 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 setiform, slightly barbed.

Legs ( Figs. 124–127 , 153–156 ). Ontogeny of leg setae and solenidia given in Tables 11 and 12. Leg IV of protonymph with formula 0–0–0–0–8 (seta tc ’ present additionally on tarsus). Many setae 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 tip. Famulus short, spiniform. All solenidia setiform, blunt-ended.

See Table 3 for explanations.

Figures

FIGURES 118–120. Pseudantarcticola georgiae, larva: 118 — dorsal view, 119 — ventral view, legs (except trochanters) not shown, 120 — lateral view, gnathosoma and legs (except trochanters) not shown. Scale bars 50 µm.

FIGURES 121–127. Pseudantarcticola georgiae, gnathosoma (121–123) and legs (124–126) of larva and leg (127) of protonymph: 121 — subcapitulum, left part, palp not shown, 122 — palp, 123 — chelicera, distal part, 124 — leg I, without trochanter, right, paraxial view, 125 — leg II, without trochanter, left, antiaxial view, 126 — leg III, right, antiaxial view, 127 — leg IV, left, antiaxial view. Scale bars (121–123) 10 µm, scale bars (124–126, 127) 20 µm.

FIGURES 128–129. Pseudantarcticola georgiae, nymphs: 128 — protonymph, dorsal view, 129 — tritonymph, dorsal view. Scale bars 100 µm.

FIGURES 130–146. Pseudantarcticola georgiae, setae of tritonymph: 130 — rostral seta, 131 — lamellar seta, 132 — interlamellar seta, 133 — sensillus, 134 — exobothridial seta, 135 — gastronotic seta la, 136 — gastronotic seta la, 137 — genital seta g2, 138 — aggenital seta ag1, 139 — anal seta an2, 140 — adanal seta ad2, 141 — epimeral seta 3b, 142 — epimeral seta 3b, 143 — epimeral seta 4c, 144 — famulus and basal parts of seta ft’’ and solenidia on leg tarsus I, 145 — distal part of seta p’’ on leg tarsus I, 146 — seta u’’ on leg tarsus I. Scale bar (130–131, 133–146) 10 µm, scale bar (132) 20 µm.

FIGURES 147–152. Pseudantarcticola georgiae, anogenital (147–149) and epimeral (150–152) regions of nymphs: 147 — anogenital region of protonymph, 148 — anogenital region of deutonymph, 149 — anogenital region of tritonymph, 150 — epimeral region of protonymph, 151 — epimeral region of deutonymph, 152 — epimeral region of tritonymph. Scale bars (147–148, 151–152) 50 µm, scale bar (149) 100 µm, scale bar (150) 20 µm.

FIGURES 153–156. Pseudantarcticola georgiae, legs of tritonymph: 153 — leg I, left, antiaxial view, 154 — leg II, without trochanter, right, antiaxial view, 155 — leg III, left, antiaxial view, 156 — leg IV, left, antiaxial view. Scale bar 20 µm.