Achipteria punctata ( Nicolet, 1855 )

Seniczak, Anna & Seniczak, Stanisław, 2018, Morphological ontogeny of Achipteria punctata (Acari: Oribatida: Achipteriidae), Zootaxa 4540 (1) : -

Achipteria punctata ( Nicolet, 1855)

(Figs. 1–10)

Oribata punctata Nicolet, 1855 . Notaspis punctatus: Sellnick 1928 . Notaspis italicus sensu Willmann 1931 . Achipteria punctatum: Forsslund 1943 . Achipteria punctata: Schweizer 1956 ; Mehl 1979. Parachipteria punctata: Hammen 1952 ; Sellnick 1960; Karppinen and Krivolutsky 1982; Golosova et al. 1983; Schatz 1983;

Karppinen et al. 1986, 1987; Marshall et al. 1987; Bernini et al. 1995; Olszanowski et al. 1996; Subías 2004, 2018; Weig-

mann 2006; Dhora 2009; Siepel et al. 2009: Bayartogtokh 2010; Miko 2016; Murvanidze and Mumladze 2016.

Morphology of adult

Adults (Figs. 1–3a) similar to that redescribed by Bayartogtokh and Ryabinin (2012) (but see Remark below). Mean length of our individuals smaller [females, mean (range) 577.8 (533–611, n=18); males 551.2 (527–572, n=15)] than reported by Bayartogtokh and Ryabinin (2012) [586 (563–605, sex not investigated)]; mean width also smaller [females, 327.5 (318–371), males 331.9 (325–338)] than in Bayartogtokh and Ryabinin (2012) [418 (392–441)]. Cheliceral setae cha longer than chb, both barbed (Fig. 3b). Palp setae sup, inf and l” on tibia finely barbed, other setae smooth (Fig. 3c). Anteroventral apophysis on genua I and II absent, genu IV curved and approximately as long as tibia IV (Fig. 4). Solenidia ω 1 and ω 2 on tarsus I slightly curved and of similar length, seta s on tarsus II with long barbs. Seta bv’’ on femur II as long as seta d, seta l’ on femur III short and leg claws smooth. Formulae of leg setae [trochanter to tarsus (+ solenidia)]: I – 1-5 -3(1)-4(2)-20(2); II – 1-5 -3(1)-4(1)-15(2); III – 2-3 -1(1)-3(1)-15; IV – 1- 2 -2-3(1)-12. Tarsi heterotridactylous.

Remarks. The shape and distribution of porose areas in the adult of A. punctata investigated here are generally similar to those investigated by Bayartogtokh (2010) and Bayartogtokh and Ryabinin (2012). In our individuals, however, porose areas A1 and A2 can also be very small, and in the former author the posterior setae are longer and porose area A3 is placed more laterally from setal pair h 1 than in our individuals. The shape and distribution of porose areas in our adults are also similar to those studied by Chistyakov (1984), except for A3, which in the latter author is absent.

FIGURE 1. Achipteria punctata , female. (a) Dorsal aspect, legs partially drawn, scale bar 50 μm, (b) location of porose area A1 (enlarged).

FIGURE 2. Achipteria punctata , female, ventral aspect, legs partially drawn, scale bar 50 μm. FIGURE 3. Achipteria punctata , adult. (a) Lateral aspect, right side, legs partially drawn, scale bar 50 μm; mouth- parts, right side, antiaxial aspect, scale bars 20 μm, (b) chelicera (Trägårdh organ indicated in ‘transparent’ area), (c) palp.

Diagnosis of juveniles

Juveniles stocky, with most prodorsal setae short and smooth, except for slightly longer and barbed seta ro, and faint reticulation of cuticle between bothridia and in posterior part of prodorsum. In larva, most gastronotal setae short, thick and barbed, except for smooth c 2, c 3 and h 2, in nymphs gastronotal setae short, thin and finely barbed. In juveniles of A. punctata , setae of l -series on legs not thickened.

FIGURE 4. Achipteria punctata , leg segments of adult (part of femur to tarsus), right side, antiaxial aspect, setae on the opposite side not illustrated, in the legend, scale bars 20 μm. (a) Leg I, genu (l’); (b) leg II, tarsus (pv’); (c) leg III; (d) leg IV.

FIGURE 5. Achipteria punctata , larva. (a) Dorsal aspect, legs partially drawn, scale bar 50 μm; (b) shape of seta lp (enlarged).

FIGURE 6. Achipteria punctata , ventral aspect of hysterosoma, legs partially drawn, scale bar 50 μm. (a) Larva, (b) protonymph.

Description of juvenile stages

Larva stocky, light brown, cuticle plicate with granular cerotegument (Fig. 5). Prodorsum subtriangular, prodorsal setae short and smooth, except for slightly longer and barbed seta ro. Mutual distance between setal pair le two times longer than between setal pair ro, but mutual distance between setal pair in only slightly longer than between pair ro. Pair le inserted closer to pair ro than to pair in. Opening of bothridium oval, with outer curved addition, bothridial seta clavate, with elongated, barbed head. Area between bothridia and in posterior part of prodorsum with gently reticulation, and ridge present between setae ex and le.

Gastronotum of larva with 12 pairs of setae, including alveolar h 3 inserted laterally at mid-length level of anal valves (Fig. 6a). Setae c 2 and c 3 short and smooth, other gastronotal setae slightly longer or of medium size (Table 1), thickened and barbed (Fig. 5), except for smooth h 2. Length of setae of d -series longer and thicker than that of l -series. Cupules not observed in plicate cuticle. Opisthonotal gland opening lateral to lm (Fig. 7a), with surrounding cuticle reticulate (Fig. 7b). Paraproctal valves (segment PS) glabrous. In larva, setae of l -series on legs not thickened.

TABLE 1 Measurements of some morphological characters of juvenile stages and adult of Achipteria punctata (mean measurements of 10 individuals in μm); Nd – not developed.

Prodorsum, prodorsal setae and reticulation of protonymph as in larva, but bothridial seta with slimmer head than in larva. Gastronotum with 15 pairs of setae due to appearance of p -series (Fig. 6b), and alveolar seta h 3 becomes setiform, retained by subsequent nymphs (Figs. 8a, 8b); all short and smooth. In protonymph, one pair of genital setae appears on genital valves, and two pairs added in deutonymph and tritonymph each (Figs. 8a, 8b), all short and smooth. In deutonymph, one pair of aggenital setae and three pairs of adanal setae appear, retained by subsequent instars, all short and smooth. In tritonymph, two pairs of short and smooth anal setae appear on anal valves (Fig. 8b). Cupules not observed in plicate cuticle. Opisthonotal gland opening as in larva, anterolateral to seta lp (Fig. 7b). In nymphs, longitudinal ridge present from bothridium in direction of seta ro and from seta ex in direction of seta ro. In tritonymph, gastronotal setae short, thin and finely barbed (Figs. 8b, 9a, 9b). Leg segments stocky, trochanters III and IV and all femora flattened, cuticle of most segments reticulate, except for tarsi. All leg setae thin and with short barbs (Fig. 10). Solenidion ω 1 on tarsus I strongly curved as depicted, seta l’ on femur III short, solenidion φ on tibia IV with coupled seta d, leg claws smooth. In tritonymph, setae of l -series on legs not thickened.

FIGURE 7. Achipteria punctata , lateral aspect, legs partially drawn, scale bars 50 μm. (a) Larva, (b) region of gla opening (enlarged), (b) tritonymph.

FIGURE 8. Achipteria punctata , ventral aspect of hysterosoma, legs partially drawn, scale bar 50 μm. (a) Deutonymph, (b) tritonymph.

FIGURE 9. Achipteria punctata , tritonymph. (a) Dorsal aspect, legs partially drawn, scale bar 50 μm; shape of seta dp (enraged).

Summary of ontogenetic transformations.

The length and shape of prodorsal setae ro, le, in and ex in A. punctata are similar in all juveniles, but in the adult in becomes long, ro and le are of medium size, and ex remains short. The bothridial seta is clavate in all instars, but in the larva the head is thicker than in the nymphs and adult. In all juveniles, the gastronotal setae c 2 and c 3 are short, but in the larva they are smooth, and in the nymphs they are finely barbed. In the larva, other gastronotal setae are slightly longer or of medium size, distinctly thickened and barbed, except for smooth h 2, but in the nymphs they become relatively shorter, thin and finely barbed. The larva has 12 pairs of gastronotal setae, including alveolar h 3, the nymphs have 15 pairs. The notogaster of adult loses setae c 1, c 3 and d -series, such that 10 pairs of gastronotal setae remain, with c 2 and la longer than other setae. The formula of gastronotal setae of A. punctata , including alveolar h 3 in the larva, is 12-15-15-15 -10 (from larva to adult), whereas the formulae of epimeral, genital and aggenital setae and that of segments PS̅AN are as in A. gigantea (Seniczak and Seniczak 2016) . The ontogeny of leg setae and solenidia of A. punctata is as in A. gigantea . In the adult, leg segments are slimmer than in the juveniles and lack ornamentation of cuticle and coupled seta d at solenidion φ on tibia IV, which is present in the deutonymph and tritonymph.

Distribution, ecology and biology

Achipteria punctata has Holartic distribution and is frequent in the Palearctic region and Santa Helena island ( Subías 2018). This species is considered a herbivorous grazer ( Siepel & Maaskamp 1994). It inhabits the mixed deciduous woodland, with oak ( Quercus spp.) dominating ( Thomas 1979), oak forest ( Murvanidze et al. 2013) and peat bogs ( Karppinen & Koponen 1973, Murvanidze & Kvavadze 2010). This species was also found in the nests of red wood ant ( Formica polyctena ) in the oak forest ( Elo et al. 2016) and in the Hypnum zone on beech in an old beech forest ( Gjelstrup 1979). It inhabits mainly the upper soil horizon ( Karppinen 1958), and in a mixed deciduous woodland in England it has two generations during the year. In moss-tundra ecosystems of Svalbard archipelago, A. punctata was not abundant ( Seniczak et al. 2014), except for the plumage of birds where it was abundant ( Lebedeva et al. 2006). This species was also recorded from trunks and stumps in the subfossil bog in southern Finland ( Karppinen & Koponen 1973).

We found this species in three samples in a deciduous forest in Mundheim-Furhovda (Co. Kvam, Norway) and in two samples in a bog in Lullymore Heritage & Discovery Park (Co. Kildare, Ireland). In the first locality, the density of this species was higher (65–189 individuals per 500 cm 3) than in the second locality (Table 2). In most samples, the juveniles dominated the adults, except one sample from Ireland, where the adults were more abundant than the juveniles. In the most abundant sample, the juveniles constituted 84% of all individuals and the stage structure was the following: 68 larvae, 76 protonymphs, seven deutonymphs, seven tritonymphs and 31 adults. The sex ratio (females to males) of A. punctata was 1:0.8, and all females were gravid, carrying two or three eggs. The eggs were relatively large (248 x 129), making about 43% of the total body length of females.

TABLE 2 Stage structure of Achipteria punctata in selected microhabitats; Lv – larva, Pn – protonymph, Dn – deutonymph, Tn – tritonymph, Ad – adult.

FIGURE 10. Achipteria punctata , leg segments of tritonymph (part of femur to tarsus), right side, antiaxial aspect, setae on the opposite side not illustrated, in the legend, scale bars 20 μm. (a) Leg I, femur (l’), tarsus (pl’); (b) leg II, genu (v’), tibia (v’), tarsus (pv’); (c) leg III, tibia (v’’); (d) region of solenidia ω 1 and ω 2 on tarsus I; (e) leg IV.