Edwardzetes elongatus Wallwork, 1966

Ermilov, Sergey G., Yurtaev, Andrey A. & Pešić, Vladimir, 2015, Additions to the Tasmanian oribatid mites, with supplementary description of Edwardzetes elongatus Wallwork, 1966 (Acari, Oribatida), Ecologica Montenegrina 2 (2), pp. 98-108 : 104-106

Edwardzetes elongatus Wallwork, 1966

( Figures 1–23 )

Measurements. Body length: 830–1029 (three specimens: one female and two males); notogastral width (without pteromorphs): 398–498 (three specimens).

Integument. Body color light brown to dark brown. Body surface smooth, but prodorsum indistinctly punctate.

Prodorsum. Rostrum widely rounded. Lamellae shorter than half of prodorsum. Lamellar cusps without teeth. Translamella absent. Rostral (ro, 90–102), lamellar (le, 151–164) and interlamellar (in, 176– 205) setae simple, slightly barbed. Bothridial setae (ss, 40–48) clavate, with short stalk (12–20) and oval, rounded distally, indistinctly barbed head (28). Tutoria (tu) sable-like, long, curving downward, pointed. Exobothridial setae (ex, 41) thin, slightly barbed.

Notogaster . Anterior margin convex. Pteromorphs broadly rounded laterally. Dorsophragmata (D) of medium size, connected medially. Four pairs of oval porose areas present, with distinct borders: Aa (28–32 × 20–22) little larger than A1, A2 and A3 (16–24 × 12–16). Ten pairs of notogastral setae setiform, with short attenuate tips, thin, smooth; p 1 – p 3 (45–49) shorter than other seven pairs (65–69). Lyrifissures ia, im, ip, ih and ips distinct. Opisthonotal gland openings (gla) located laterally to A1.

Gnathosoma. Subcapitulum longer than wide (233–246 × 172–180). Subcapitular setae setiform, slightly barbed; a (36–41) shorter than h and m (both 53–57). Adoral setae and their alveoli absent. Palps (147) with setation 0–2–1–3–9(+ω). Solenidion attached to eupathidium, both located on dorsal tubercle. Chelicerae (266–287) with two simple, barbed setae; cha (102–106) longer than chb (45–49). Trägårdh’s organ (Tg) long, tapered.

Lateral podosomal and epimeral regions. Pedotecta I (Pd I) large, concave in dorsal view. Pedotecta II (Pd II) of medium size, triangular in ventral view. Both pedotecta scale-like in lateral view. Genal teeth (gt) elongate narrowly triangular. Apodemes 1, 2, sejugal and 3 distinctly developed, not fused medially. Epimeral setal formula 3–1–3–3. Epimeral setae setiform, thin, indistinctly or slightly barbed; setae 1b, 3b and 3c (61–73) longer than other (45–49). Custodia (cus) with long, thin, pointed tips. Discidia (dis) triangular. Circumpedal carinae (cp) distinct.

Anogenital region. Six pairs of genital (g 1 – g 6), one pair of aggenital (ag), two pairs of anal (an 1, an 2) and three pairs of adanal (ad 1 – ad 3) setae similar in length (36–41), simple, thin, indistinctly barbed. Lyrifissures iad located close to anal aperture, in inverse apoanal position. Ovipositor elongated (274 × 62), blades (106) shorter than length of distal section (beyond middle fold; 168). Each of three blades with four straight, smooth setae, ψ 1 ≈ τ 1 (53–57) longer than ψ 2 ≈ τa ≈ τb ≈ τc (24–28). Six coronal simple setae (k, 14– 16) present.

Legs. Medial claw smooth, clearly thicker than two laterals; claws serrate (ser) dorsally. Genua I and II, and femora II with large, triangular antero-ventral tooth (t). Formulae of leg setation and solenidia: I (1– 5–3–4–20) [1–2–2], II (1–5–3–4–16) [1–1–2], III (2–2–1–3–15) [1–1–0], IV (1–2–2–3–12) [0–1–0]; homology of setae and solenidia as indicated in Table 2 . Solenidia setiform, thin, pointed. Famulus (ɛ) short, blunted. Setae (except p) slightly barbed.

Remarks. The specimens of E. elongatus from Tasmania show general conformity with the original description ( Wallwork 1966) from the South Georgia Islands. However, detailed comparison of the Tasmanian specimens with those from the Starý collection revealed differences in the following characters:

1) Setae l” on genua II. These setae in the Tasmanian specimens were simple, slightly thickened versus thorn-like in specimens from South Georgia Island.

2) Morphology of rostral, lamellar and anogenital setae. These setae in the Tasmanian specimens were slightly barbed versus distinctly barbed in specimens from South Georgia.

In our opinion, the above listed differences are intraspecific and perhaps can be explained as population variation. Hence, this species of geographic variability could be seen in future identification of E. elongatus .

Distribution. Earlier, E. elongatus was registered in the Antarctic Islands ( South Georgia and South Sandwich Islands) and South Chile ( Wallwork 1966, 1967; Starý & Block 1995). Taking our record, geographical distribution of this species has expanded and includes now the Australian region (Tasmania) (see Fig. 23 ).

Figures

Figure 1. Edwardzetes elongatus Wallwork, 1966, adult: dorsal view. Scale bar 200 μm.

Figure 2. Edwardzetes elongatus Wallwork, 1966, adult: ventral view (legs not illustrated). Scale bar 200 μm.

Figures 3–6. Edwardzetes elongatus Wallwork, 1966, adult: 3 — lateral view of anterior part of body (legs not illustrated); 4 — subcapitulum, right half, ventral view; 5 — palptarsus; 6 — chelicera, paraxial view. Scale bars 200 μm (3), 50 μm (4, 6), 20 μm (5).

Figures 7–10. Edwardzetes elongatus Wallwork, 1966, adult: 7 — leg I (without trochanter), left, antiaxial view; 8 — femur, genu and tibia of leg II, right, antiaxial view; 9 — trochanter, femur and genu of leg III, right, antiaxial view; 10 — leg IV, right, antiaxial view. Scale bar 100 μm.

Figures 11–18. Edwardzetes elongatus Wallwork, 1966, adult, microscope images: 11 — rostral seta; 12 — bothridial seta; 13 — medio-distal part of interlamellar seta; 14 — genal tooth; 15 — medio-distal part of tutorium; 16 — notogastral seta p1; 17 — genu and anterior part of femur of leg I, left, antiaxial view; 18 — genu and anterior part of femur of leg II, left, antiaxial view. Scale bar 20 μm.

Figures 19–22. Edwardzetes elongatus Wallwork, 1966, adult, microscope images: 19 — custodium and discidium; 20 — genital plates; 21 — adanal lyrifissures, adanal seta ad3 and part of anal plate; 22 — claws of leg III. Scale bar 20 μm.

Figure 23. Map of geographical distribution of Edwardzetes elongatus Wallwork, 1966.