Achipteria nitens ( Nicolet, 1855 )

Seniczak, Stanisław, Seniczak, Anna, Kaczmarek, Sławomir & Marquardt, Tomasz, 2019, Morphological ontogeny, ecology and some biological parameters of Achipteria nitens (Acari: Oribatida: Achipteriidae), Zootaxa 4717 (1), pp. 30-46 : 30-46

Achipteria nitens ( Nicolet, 1855)

( Figs. 1–10 )

Oribata nitens Nicolet, 1855 .

Notaspis nitens: Oudemans 1914 . Achipteria nitens: Hammen 1952 ; Karppinen and Krivolutsky 1982; Golosova et al. 1983; Schatz 1983; Tarman 1983; Karp- pinen et al. 1986, 1987; Marshall et al. 1987; Bernini et al. 1995; Olszanowski et al. 1996; Subías 2004; Weigmann 2006; Erman et al. 2007; Siepel et al. 2009; Bayartogtokh 2010; Miko 2016; Murvanidze and Mumladze 2016.

Morphology of adult

Adults investigated herein ( Figs. 1–4 ) similar to that studied by Bayartogtokh and Ryabinin (2012) and Weigmann (2006), but see Remarks below. Mean length and maximum width (and range) of females= 717.3 (676–757, n= 92) and 444.0 (390–488), and males= 675.5 (652–708, n= 58) and 408.8 (364–449), respectively. Ventral plate between anal and genital plate punctate ( Fig. 2 ). Palp setae sup, inf and l” on tibia finely barbed, other setae smooth ( Fig. 3c ). Cheliceral setae cha longer than chb, both barbed ( Fig. 3d ). 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 longer than seta d, seta l’ on femur III of medium size and leg claws smooth. Formulae of leg setae (+ solenidia, trochanter to tarsus): 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. Our individuals are similar to those investigated by Weigmann (2006, 600–780), but are larger than those investigated by Pérez-Íñigo (1972, length 620–700, width 440–510), and Bayartogtokh and Ryabinin [2012, length 626 (603–640), width 379 (368–391)], in all papers sex was not investigated. In these mites, lyrifissure im is located closer to seta lm, and setae lp, h 3 and h 2 are shorter than in the adults studied by Bayartogtokh and Ryabinin (2012). Longer setae lp, h 3 and h 2 are also in the adult studied by Weigmann (2006) than in our individuals.

Diagnosis of juveniles

Juveniles stocky, plicate. Larva with short, thick and barbed setae in and of c -series, and anterior part of prodorsum reticulate, nymphs with most gastronotal setae of medium size, except for shorter c 3, and shorter, thick and smooth p 2 and p 3.

Description of juvenile stages

Larva stocky, light brown, cuticle plicate with granular cerotegument. Prodorsum subtriangular, anterior part re- ticulate, most prodorsal setae short and smooth, except for thick in and slightly longer ro ( Fig. 5 ). Mutual distance between setal pair in two times longer than between setal pairs le and ro. Pair le inserted approximately midway between pairs ro and in. Opening of bothridium oval, with outer ridge, bothridial seta clavate, with elongated, barbed head. Posterior part of prodorsum porose, and ridge present between bothridium and seta le.

Gastronotum of larva with 11 pairs of setae, including h 2 inserted laterally to posterior part of anal valves ( Figs. 6a , 7a ), seta h 3 absent. Setae of c -series short, thick and finely barbed, c 1 slightly longer than other setae ( Table 3 ). Most gastronotal setae of medium size, thick and barbed, except for short and thick c -series and smooth h 2. Setae of d -series slightly longer than of l -series. Cupules not observed in plicate cuticle. Opisthonotal gland opening antero- lateral to seta lm ( Fig. 7a ). Paraproctal valves (segment PS) glabrous.

Shape of prodorsum, prodorsal setae of protonymph as in larva, but bothridial seta with slimmer head than in larva. In all nymphs, longitudinal ridge present between bothridium and seta ro. Seta le between longitudinal ridges, and area between bothridia with dense short spicules. Gastronotum of protonymph with 15 pairs of setae due to appearance of seta h 3 and p -series ( Fig. 6b ), retained in subsequent nymphs ( Figs. 8a, 8b ); most of medium size, thick and barbed, except for shorter c 3 and shorter and smooth p 2 and p 3. In protonymph, one pair of genital setae appearing on genital valves, and two pairs added in deutonymph and tritonymph each; all short and smooth. In deutonymph, one pair of aggenital setae and three pairs of adanal setae appearing, and retaining in subsequent instars; ag thin and smooth, other setae thicker, ad 1 of medium size and barbed, ad 2 and ad 3 short, thick and smooth ( Fig. 8a ). In tritonymph, two pairs of short and smooth anal setae appearing on anal valves ( Fig. 8b ); most gastronotal setae of medium size, thick and barbed ( Figs. 7b , 9 ), except for shorter c 3 and shorter, thick and smooth p 2 and p 3. Setae of d -series slightly longer than of l -series. Cupules not observed in plicate cuticle. Opisthonotal gland opening anterolateral to seta lp ( Fig. 7b ). Leg segments stocky, trochanters III and IV and all femora flattened, cuticle of most segments reticulate, except for tarsi, solenidion φ on tibia IV with coupled seta d, and leg claws smooth ( Fig. 10 ).

Summary of ontogenetic transformations

The length and shape of prodorsal setae are similar in all juveniles of A. nitens , but in the adult in is long, ro and le are of medium size, and ex is 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, most gastronotal setae are of medium size, thick and barbed, but in the larva setae of c -series are shorter than other setae, whereas in the nymphs shorter is c 3, and p 2 and p 3 are short and smooth. The larva has 11 pairs of gastronotal setae, including h 2, but seta h 3 is absent; the nymphs have 15 pairs (h 3 and p -series are added). 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. nitens is 11-15-15-15 -10 (from larva to adult), whereas the formulae of epimeral, genital and aggenital setae and that of segments PS−AN are as in A. gigantea (Seniczak & Seniczak 2016) . The ontogeny of leg setae and solenidia of A. nitens is as in A. gigantea . The leg segments of the adult 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 nitens has a Holartic distribution and is frequent in Palearctic and Virginia ( USA) ( Subías 2019). This species is silvicolous, bryophilous, praticolous ( Perlinger & Schatz 2009) and belongs to panphytophages ( Schatz 1983). It prefers oak ( Quercus sp.) forest ( Calugar et al. 2006), but is also abundant in moss, herbs and hawthorn litter in steppe bushes of Crimea ( Seniczak et al. 2011). This species achieved the highest density in hawthorn litter (403 individuals per 500 cm 3), and the juveniles constituted 43% of all individuals. Achipteria nitens inhabited in lower densities yew and cypress litter in forested area in southern Italy ( Seniczak & Seniczak 2012), moss and pine litter in open and forested habitats of Korčula Island ( Croatia) ( Seniczak et al. 2013) and galena-calamine mining wastelands in Poland ( Skubała 1996).

In this investigation, A. nitens was very abundant in steppe bushes (369–939 individuals per 500 cm 3), achieving the highest density in hawthorn litter, and lowest density in moss growing on hawthorn litter ( Table 1 ). In these samples, females dominated males (sex ratio 1:0.5–1:0.9, Table 2 ), and the percent of juveniles varied from 37% to 68% of all individuals. In the most abundant sample, the juveniles constituted 53% of all individuals, and the stage structure was the following: 396 larvae, 23 protonymphs, 35 deutonymphs, 47 tritonymphs and 438 adults. Most females were gravid (80–100%), carrying one to four eggs (usually one or two eggs). The eggs were relatively large (330 x158), making about 49% of the total body length of females.

The largest females and males occupied hawthorn litter, but these mites were not significantly larger than in other microhabitats ( Table 2 ). In most microhabitats, males was significantly smaller than females, except for hawthorn litter.

Figures

FIGURE 1. Achipteria nitens, female. (a) Dorsal aspect, legs partially drawn, scale bar 100 μm, (b) head of bothridial seta (enlarged).

FIGURE 2. Achipteria nitens, female, ventral aspect, legs partially drawn, scale bar 100 μm (punctation of anogenital plate is shown).

FIGURE 3. Achipteria nitens. (a) Female with ejected ovipositor, lateral aspect, legs partially drawn, scale bar 100 μm; (b) shape of tutorium (enlarged); mouthparts, right side, antiaxial view, scale bars 20 μm; (c) palp, (d) chelicera (Trägårdh organ indicated in ‘transparent’ area).

FIGURE 4. Achipteria nitens, adult, part of femur, genu, tibia and tarsus shown from right side, setae on the opposite side are not illustrated, but indicated in the legend, scale bars 50 μm. (a) Leg I, genu (l’), tarsus (pl’); (b) leg II; (c) leg III, tibia (v’’); (d) leg IV.

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

FIGURE 6. Achipteria nitens, ventral side of hysterosoma, legs partially drawn, scale bars 50 μm. (a) Larva, (b) protonymph.

FIGURE 7. Achipteria nitens, lateral aspect, legs partially drawn, scale bars 50 μm. (a) Larva (reticulation of femur I is shown), (b) tritonymph.

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

FIGURE 9. Achipteria nitens, tritonymph. (a) Dorsal aspect, legs partially drawn, scale bar 100 μm, (b) shape of seta dp (enlarged).

FIGURE 10. Achipteria nitens, leg segments of tritonymph (part of femur to tarsus), right side, setae on the opposite side not illustrated, but indicated in the legend, scale bar 50 μm. (a) Leg I, femur (l’), tarsus (pl’), reticulation of femur is shown; (b) leg II, femur (l’), tibia (v’), tarsus (pv’); (c) leg III; (d) leg IV.

Tables

TABLE 3. Measurements of some morphological characters of all instars of Achipteria nitens from Crimea penin- sula (mean measurements of 10 individuals in μm), Nd—not developed.

Characters	Larva	Protonymph	Deutonymph	Tritonymph	Adult
Body length	298	398	465	611	708
Body width	190	202	290	371	465
Lengh of prodorsum	83	102	116	132	120
Length of: seta bs	60	72	79	102	106
seta ro	15	18	21	23	69
seta le	2	2	2	3	77
seta in	2	2	2	3	168
seta ex	2	2	2	3	19
seta c 1	5	9	12	28	Lost
seta c 2	4	8	11	27	104
seta c 3	3	5	6	12	Lost
seta da	16	18	25	41	Lost
seta dp	22	29	33	52	Lost
seta la	13	13	22	35	84
seta lp	20	30	34	48	27
seta h 1	16	12	25	32	36
seta h 2	15	12	17	26	30
seta h 3	Nd	20	27	35	38
seta p 1	Nd	10	16	24	35
Genital opening	Nd	25	38	58	86
Anal opening	81	95	121	160	141