Alaskozetes antarcticus intermedius Wallwork, 1967

Ermilov, Sergey G., Stary, Josef & Block, William, 2012, Morphology of juvenile instars of Ameronothridae (Acari: Oribatida), Zootaxa 3224 (1), pp. 1-40 : 3-10

Alaskozetes antarcticus intermedius Wallwork, 1967

( Figs. 1–41 )

Dimensions. Length: larva 431–464 (n=2), protonymph 657–664 (n=3), deutonymph 814–847 (n=4), tritonymph 996–1112 (n=9). Width: larva 232–249 (n=2), protonymph 348–365 (n=3), deutonymph 431–448 (n=4), tritonymph 597–647 (n=9).

Integument. General body cuticle weakly sclerotized, colourless to yellow-grey and yellow-brownish. Legs 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 straight, parallel longitudinal folds in middle-lateral part; one transverse fold located between bothridia. Cuticle of proximolateral region of prodorsum and of gastronotic, anogenital and sternal regions folded. Cuticle of lateral gastronotic regions with folds, extending on to ventral side. Cuticle of lateral parts of epimeres smooth. Gastronotic region with 11 or 10 (rarely) pairs of porose sclerites (one pair lateral to setae da present or absent); seven lateral pairs larger than medial sclerites. Middle-posterior region of prodorsum, and regions posterior to bothridia with porose sclerite. Lateral region with porose sclerite surrounding each the opisthonotal gland opening (gla).

Prodorsum ( Figs. 1, 3 , 8–15 ). 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 (ro) seta weakly thickened, barbed mediodistally, their tips diverging. Lamellar (le) seta short, barbed, almost spiniform. Exobothridial (ex) seta smooth. Interlamellar (in) seta longest on prodorsum, thickened, with numerous barbs. Sensillus (ss) longer than diameter of bothridium, with developed stalk and oval, slightly barbed head. Relative length of prodorsal setae for all juvenile instars: in> ro> ss> le> ex. Prodorsal setae measurements given in Table 1.

*Number of studies specimens.

Gastronotic region ( Figs. 1, 3 , 8–9 , 16–18 ). Relatively flattened in lateral view; rounded posteriorly. Larva with 12 pairs and nymphs with 15 pairs of gastronotic setae. All setae set on small tubercles, thickened (except h 3 in larva), barbed. Larval (lp, h 1, h 2) and nymphal (h 1, h 2, h 3, rarely also lp) posterior setae longer than others; setae c 2 often shortest on dorsal side. Cupules ia and im not evident among cuticular folds; ip and opisthonotal gland opening poorly visible.

Anogenital region ( Figs. 2 , 19–22 , 28–30 ). 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 and smooth. Cupules ih, ips, and iad poorly visible (except when located near paraprocts), appearing in normal ontogenetic pattern.

Epimeral region ( Figs. 2 , 23–24 , 31–33 ). 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 3–1–2–3. All setae short (only 1b long and often lateral setae little longer) and smooth.

Gnathosoma ( Figs. 34–37 ). 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; Fig. 35 ). Palp setal formula 0–2–1–3–9+1ω. Palpal solenidion ω and eupathidium acm connected, forming double horn. Cheliceral seta cha thickened, heavily barbed, little longer than setiform and barbed chb.

Legs ( Figs. 4–7 , 25–27 , 38–41 ). Ontogeny of leg setae and solenidia given in Tables 2 and 3. Leg IV of protonymph with formula 0–0–0–0–8 (seta s present on tarsus). Many setae thickened, with strongly barbs. Seta u thick, with several large barbs in basal part and setiform, smooth in medio-distal part. Setae u, a, p, it and tc with expanded, oval or rounded tip. Famulus short, spiniform. All solenidia setiform, blunt-ended.

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Roman letters refer to normal setae (e — famulus), Greek letters refer to solenidia. One apostrophe (') marks setae on anterior and double apostrophe (") setae on posterior side of the given leg segment. Parentheses refer to a pair of setae. Setae are listed only for the instar in which they first appear.

Figures

FIGURES 1–3. Alaskozetes antarcticus intermedius, larva: 1 — dorsal view, 2 — ventral view, legs (except trochanters) not shown, 3 — lateral view, gnathosoma and legs (except trochanters and femora) not shown. Scale bars 100 µm.

FIGURES 4–7. Alaskozetes antarcticus intermedius, legs (4–6) of larva and leg (7) of protonymph: 4 — leg I, without trochanter, right, antiaxial view, 5 — leg II, without trochanter, right, antiaxial view, 6 — leg III, without trochanter, left, antiaxial view, 7 — leg IV, right, antiaxial view. Scale bar (4–6) 20 µm, scale bar (7) 50 µm.

FIGURES 8–9. Alaskozetes antarcticus intermedius, nymphs: 8 — protonymph, dorsal view, 9 — tritonymph, dorsal view. Scale bar (8) 100 µm, scale bar (9) 200 µm.

FIGURES 10–27. Alaskozetes antarcticus intermedius, setae of tritonymph: 10 — rostral seta, 11 — lamellar seta, 12 — lamellar seta, 13 — interlamellar seta, 14 — sensillus, 15 — exobothridial seta, 16 — gastronotic seta c1, 17 — gastronotic seta c2, 18 — gastronotic seta h2, 19 — genital seta g2, 20 — aggenital seta ag1, 21 — anal seta an2, 22 — adanal seta ad2, 23 — epimeral seta 1b, 24 — epimeral seta 4c, 25 — famulus and basal parts of seta ft’’ and solenidia on leg tarsus I, 26 — seta u’ on leg tarsus I, 27 — distal part of seta tc’’ on leg tarsus I. Scale bar (10–12, 14–27) 10 µm, scale bar (13) 20 µm.

FIGURES 28–33. Alaskozetes antarcticus intermedius, anogenital (28–30) and epimeral (31–33) regions of nymphs: 28 — anogenital region of protonymph, 29 — anogenital region of deutonymph, 30 — anogenital region of tritonymph, 31 — epimeral region of protonymph, 32 — epimeral region of deutonymph, 33 — epimeral region of tritonymph. Scale bars (28–29, 33) 100 µm, scale bar (30) 200 µm, scale bars (31–32) 50 µm.

FIGURES 34–41. Alaskozetes antarcticus intermedius, gnathosoma (34–37) and legs (38–41) of tritonymph: 34 — subcapitulum, right part, palp (except trochanter), lips and adoral setae not shown, 35 — adoral setae, 36 — palp, 37 — chelicera, distal part, 38 — leg I, right, antiaxial view, 39 — leg II, right, antiaxial view, 40 — leg III, right, antiaxial view, 41 — leg IV, right, antiaxial view. Scale bar (34) 50 µm, scale bars (35–36) 10 µm, scale bar (37) 20 µm, scale bar (38–41) 100 µm.