Oribatula heterochaeta
Creators: name: Seniczak, Stanisław
name: Seniczak, Anna
name: Kaczmarek, Sławomir
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Sarcoptiformes
Oribatulidae
Oribatula
Oribatula heterochaeta

description: Oribatula heterochaeta (Feider et al., 1970)
(Figs 1–16)
Zygoribatula heterochaeta: Feider et al. (1970)
Oribatula (Zygoribatula) heterochaeta: Subías (2004)
Diagnosis
Adult. The diagnosis of adult of O. heterochaeta was given by Feider et al., (1970b). We can add to this diagnosis the following characters: length 390–475, bothridial seta fusiform. Notogaster smooth, microporose with anterior shoulder and 14 pairs of setae, including c 1, c 2 and p 3, most short, curved and smooth except for slightly longer, straight and finely barbed c 2. Porose areas (4 pairs) small, oval, Aa slightly larger than other porose areas. Seta v' on genu II absent.
Juveniles. Most prodorsal setae of juveniles of medium size or long, bothridial seta clavate. Larva with 12 pairs of gastronotal setae, nymphs with 15 pairs, all of medium size and finely barbed except for short and smooth h 3 in larva and p 3 in protonymph and deutonymph. In larva basal excentrosclerites present at four pairs of setae (c 2, la, lp, h 1), and in nymphs at seven pairs (c 2, da, dp, h -series, p 1).
Morphology of adult
Adults (Figs 1a, 2, 3, 4a, 5–9) similar to that described by Feider et al. (1970) [but see Remarks]. Mean length (and range) of females 452.5±15.8 (429–475, n= 14) and males 409.5±9.7 (390–429, n= 26), mean width (and range) of females 296.2±8.7 (273–325) and males 257.2±7.5 (241–273). Cerotegument microporose in light microscopy, with 6–8 pits between setal pair da, many pits between bothridium and basal parts of legs and in anogenital region (Figs 1a, 4a, 5a, 5b, 5d, 6). Cerotegument thin and content of digestive tract shines through it. In SEM figures folds and depressions visible on the prodorsum and notogaster (Figs 6, 7a). Prodorsal setae (4 pairs) of medium size or long, all finely barbed. Sejugal porose areas Ad and Ah oval (Figs 1a, 4a). Most notogastral setae (14 pairs, including c 1, c 2 and p 3) short and smooth except for medium-sized and finely barbed c 2 (Figs 1, 2, 3, 4a, 5, 6, 7a, Table 1). Four pairs of oval porose areas present, Aa clearly larger than other porose areas. Opisthonotal gla opening located anterolateral to seta lp. Lyrifissure ia located posterolateral to seta c 2, im anterior to seta lp, ip between setae p 1 and p 2, iad anterior to anal plate, ips and ih anterolateral to seta p 3 (Figs 1a, 2, 3, 4a). Subcapitular seta h, m and a short and finely barbed (Figs 2, 5c, 7d). Chelicera chelate-dentate, with short, finely barbed setae, cha slightly longer than chb, palp relatively short, with setae of medium size and finely barbed (Fig. 4b, 4c, 7b–d), formula of palp setae (trochanter to tarsus + solenidion ω): 0-2-1-3-9(1).
All femora flattened, with ventral carina, most leg setae with short barbs, seta ft'' on tarsus I relatively long (Figs 5, 7b, 8c, 8d, 9). Formulae of leg setae (and solenidia), trochanter to tarsus: I—1-5-(3+1)-(4+2)-(20+2); II—1-5- (2+1)-(4+1)-15; III—2-3-(1+1)-(3+1)-15; IV—1-2-2-(3+1)-12 (Table 2). Leg tarsi heterotridactylous.
Remarks. The body size of adults investigated here is larger than that described by Feider et al. (1970)— length 434, width 279 (sex was not investigated), but the body shape and the distribution of the prodorsal and notogastral setae are similar to that described by Feider et al. (1970). In our individuals of O. heterochaeta the translamella are slightly narrower, the head of bothridial setae is slimmer and the porose areas are slightly smaller than in the adult drawn by Feider et al. (1970) which might be slightly caused by the technique of preparation of figures. In our individuals seta v' on genu II is absent as in that described by Feider et al. (1970).
Description of juvenile stages
Larva elongated (Figs 10a, 11a, 12a) and colorless. Prodorsum subtriangular, setae ro, le and in of medium size and barbed, ro longest, le shortest (Table 1), seta ex short and smooth. Mutual distance between setal pair le approximately two times longer than that between setal pair ro, and mutual distance between setal pair in approximately six times longer than that between setal pair ro, setae le inserted slightly closer to in than to ro (Figs 10a, 12a). Bothridium rounded, bothridial seta of medium size and clavate, with thick, barbed head. Prodorsal shield well-developed.
Gastronotum of larva with 12 pairs of setae, including h 3 located lateral to medium part of anal valves. Most setae of medium size and finely barbed, except for short and smooth h 3 (Figs 9a, 11a, 12a, Table 1). Setae c 2, la, lp and h 1 with basal excentrosclerites, other setae without excentrosclerites, excentrosclerite at seta c 2 largest. Gastronotal shield weakly developed. Cupule ia posterior to seta c 3, cupule im posterior to seta lm, cupule ip between setae h 1 and h 2, cupule ih lateral to anterior part of anal valves, opisthonotal gland opening gla anteroventral to seta lp (Figs 10a, 11a, 12a). Paraproctal valves (segment PS) with two pairs of short and smooth setae. Most leg setae of medium size and finely barbed, seta ft'' on tarsus I relatively long, but clearly shorter than ft' (Fig. 13).
Prodorsum and prodorsal setae of protonymph as in larva, but head of bothridial seta slimmer than in larva. Gastronotum of protonymph with 15 pairs of setae because two pairs of setae migrate from anal valves of larva and one pair added on PS segment and present in deutonymph and tritonymph (Figs 11b, 14a, 14b), length decreasing from p 1 to p 3; most finely barbed except for smooth p 3. In protonymph, one pair of genital setae appearing, and one pair added each in deutonymph and tritonymph. In deutonymph, one pair of aggenital setae and three pairs of adanal setae appearing and present in tritonymph, all short and smooth; in some individuals additional adanal and anal setae present on one side (Figs 14a, 14b). Most gastronotal setae of deutonymph and tritonymph of medium size, strait, acuminate and finely barbed except for long c 3 and smooth p 3 in deutonymph (Figs 12b, 14a, 14b, 15). Gastronotal shield of nymphs weakly developed, with setae c 2, la, lp, p 1 and h -series with basal excentrosclerites, other setae without excentrosclerites, excentrosclerite at seta c 2 larger than at other setae. Paraproctal valves of proto- and deutonymph glabrous, those of tritonymph with two pairs of short and smooth seta. Cupules ia and im located as in larva, cupule ip between setae h 2 and p 2, cupule iad lateral to anterior part of paraproctal valves, cupule ips and ih pushed to lateral and anterolateral to cupule iad respectively (Figs 12b, 14b, 15). Gland opening gla located anterolateral to seta lp. Most leg setae of medium size and finely barbed. Seta ft'' on tarsus I relatively long and located posteromedial to solenidion ω 2 (Fig. 16).
Summary of ontogenetic transformations
In the larva, protonymph and deutonymph of O. heterochaeta seta ro is longer than seta in, whereas in the tritonymph and adult in is longer than ro. In all instars, the bothridium is rounded, but in the juveniles the bothridial seta is clavate and fusiform in the adult. The larva has 12 pairs of gastronotal setae, including h 3, the nymphs have 15 pairs (in protonymph two pairs of setae migrate from anal valves of larva and one pair added on PS segment), while the notogaster of the adult losses seta c 3, and 14 pairs of setae remain. The formula of the gastronotal setae is 12-15-15-15-14 (larva to adult), and those of the epimeral setae are: 3-1-2 (larva, including scaliform 1c), 3-1-3-1 (protonymph), 3-1-3-2 (deutonymph) and 3-1-3-3 (tritonymph and adult). The formula of the genital setae is 1-2-3-4 (protonymph to adult), and that of the aggenital setae is 1-1-1 (deutonymph to adult). The formula of the segments PS–AN is 23333-0333-022. Ontogeny of the leg setae and solenidia of O. heterochaeta is given in Table 2.
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Note: structures are indicated where they are first added and are present through the rest of ontogeny; pairs of setae in parentheses, dash indicates no additions.
Distribution, ecology and biology
Oribatula heterochaeta has been formerly known only from Romania (Subías 2004, 2022). This species was found in dry litter in rodent-nest tunnel (Feider et al. 1970a) and oak litter in oak forests (Ivan & Vasiliu 1999). It was relatively abundant in Quercus pubescens forests (Ivan 2006), and tolerated pollution with heavy metals and fluorine (Ivan & Vasiliu 2009).
In this study, this species was collected from cypress and spruce litter in Sunny Beach (Nesebar, Burgas, Bulgaria). In the cypress litter the density was 279 individuals per 500 cm 3, and the juveniles constituted 90% of all individuals. The stage structure of O. heterochaeta was the following: 14 larvae, 9 protonymphs, 99 deutonymphs, 128 tritonymphs and 29 adults. In the spruce litter the density was 132 individuals per 500 cm 3, and the juveniles constituted 53% of all individuals. The stage structure of this species was the following: 2 larvae, 9 protonymphs, 31 deutonymphs, 28 tritonymphs and 62 adults. Among 30 individuals investigated the sex ratio (females to males) was 1:1.9. Most females (70%) were gravid carrying 4–8 large eggs (usually 6 large eggs), each 154 x 75 constituting 34% of body length of females. In the digestive tract of most juveniles and adults many rounded pollen grains of plants were observed.
description: Published as part of Seniczak, Stanisław, Seniczak, Anna & Kaczmarek, Sławomir, 2023, Morphological ontogenyofOribatulaheterochaeta (Acari, Oribatida, Oribatulidae) with comments on some species of Oribatula Berlese, pp. 83-109 in Zootaxa 5324 (1) on pages 85-97, DOI: 10.11646/zootaxa.5324.1.9, http://zenodo.org/record/8213922