Jacotella neonominata Subías, 2004

Seniczak, Stanisław & Seniczak, Anna, 2011, Ontogenetic studies of three species of Gymnodamaeidae (Acari: Oribatida) with a focus on regressions of hysterosomal setae, Journal of Natural History 45 (5 - 6), pp. 361-391 : 381-385

Jacotella neonominata Subías, 2004

( Figures 8D , 10B , 14–17 )

Plesiodamaeus ornatus Pérez-Íñigo, 1972 .

Jacotella ornata ( Pérez-Íñigo, 1997) .

Diagnosis

Adults oval ( Figure 14 ), brown and rather small (353–545 µm). Rostrum triangular, rounded, with two pairs of setae positioned in one row (setae le between ro), both pairs rather long, thick, and covered with granules of cerotegument. Lateral outline with pedotecta I and II, relatively smaller than in A. reticulatus . Seta ex short, seta in minute. Bothridium well-developed, rounded, sensillus long with relatively large, spatulate and barbed head.

Notogaster almost flat, oval, with large-scale reticulation of cerotegument and four pairs of posterior setae (h 1, p 1 – p 3) ( Figure 10B ). Formula of epimeral setae, number of genital, aggenital, adanal and anal setae as in A. reticulatus . Formula of leg setae (trochanter to tarsus, solenidia in parentheses): I – 1-5-4(1)-5(2)-18(2); II – 1-4-4(1)- 5(1)-15(2); III – 2-3-3(1)-4(1)-14; IV – 1-2-3-4(1)-12. Legs tridactylous.

Juveniles generally similar to adult, but cuticle less sclerotized and unpigmented. Prodorsal setae ro and le relatively long, setae ro positioned slightly wider from each other than setae le; seta ex short, seta in minute. Gastronotum of larva with 11 pairs of spatulate setae (h 3 absent), with d -series larger than others; nymphs with 10 pairs of gastronotal setae (d -series absent, h 3 and p -series present), with c 3 and lp rather short, and with small excrescence on posterior part of body, bearing four curved setae (h 1 and p 1).

Description of juvenile stages. Larva oval, elongated ( Figure 15 ), body unpigmented. Prodorsum triangular, with rounded rostrum, lateral outline with depressions above level of legs I and II. Setae ro and le rather long, curved and barbed; setae ex and in short and spatulate. Bothridium well-developed, rounded, sensillus long, with narrow, barbed head.

Larval gastronotum with 11 pairs of setae, including seta h 2 positioned laterally to posterior part of anal opening ( Figure 16A ). All gastronotal setae spatulate and positioned on apophyses, which vary directly to size of seta. Setae dm and dp longer, especially seta dp, other setae short. Paraproctal valves (segment PS) with two pairs of small setae. Cupules ia, im, ip and ih as in A. reticulatus . Gastrototum with transverse lines of granules of cerotegument, lateral parts gently striated.

Nymphal stages oval in shape, and unpigmented. Gastronotum of protonymph with 10 pairs of setae: h 3 and p 1 – p 3 appear and remain in deutonymph and tritonymph; setae la, lm and d -series lost and remain absent in subsequent stages ( Figure 16B ), as in A. reticulatus . Excrescence on posterior part of nymphs small, with two pairs of setae, positioned dorsally (h 1) and laterally (p 1); p 1 shorter than h 1, but curved anteriorly, as in A. reticulatus . Numerical changes of setae on ventral side generally as in A. reticulatus , except number of genital setae ( Table 2). Anogenital region with folds and granules of cerotegument, often forming lines.

Nymphs with exuviae weakly connected with gastronotum, as in A. reticulatus ; cuticle of exuviae with small foveolae ( Figure 17 ). Prodorsum, prodorsal setae and bothridium of nymphs as in larva, but sensillus with slimmer head. Seta c 3 extremely long, setiform, lying on exuviae, other setae shorter and spatulate. Setae lp, h 3, h 2 and h 1 positioned in row on margin of gastronotum; seta h 2 small, but length of other setae increasing from seta lp to h 1. Posterior excrescence small; seta h 1 hardly at all curved, p 1 curved anteriorly. Cupules ia, im, ip, ian, iad, ips and ih as in A. reticulatus . Gastronotum with granules of cerotegument, lateral parts with folds. Tarsus I shorter, and solenidia ω 1 and ω 2 relatively longer than in A. reticulatus and G. bicostatus ; ω 1 slightly longer than ω 2, and pointed, ω 2 blunt ( Figure 8D ). Famulus ε relatively longer than in A. reticulatus . Tibia with two solenidia, ϕ 1 long, ϕ 2 short, but relatively longer than in A. reticulatus .

Summary of ontogenetic transformations

During ontogeny of J. neonominata , five pairs of setae are present on the prodorsum. Setae ro and le are rather long in all instars, but setae in and ex are short and spatulate in the larva, and small and setiform in the nymphal stages; in the adult seta ex becomes longer but seta in remains minute. The bothridium is well-developed and rounded in all instars, and the sensillus has a narrow, barbed head in the larva, thicker in the nymphs, spatulate and barbed in the adult. The larva has 11 pairs of gastronotal setae, while nymphs have 10 pairs; numeric changes of these setae in the juveniles are as in A. reticulatus . The adult loses setae of c -series, lp, h 2 and h 3, and only four pairs of notogastral setae remain (h 1 and p -series). The formulae of coxisternal, aggenital and gastronotal setae, and setae of segments PS-AN, are as in A. reticulatus ; the formula of genital setae is given in Table 2. Ontogeny of cupules ia, im and ip as in A. reticulatus ; in the adult, lyrifissures ih, ips, iad and ian are difficult to observe under the cerotegument.

Distribution and ecology

Jacotella neonominata is a Mediterranean species ( Subías 2004). It has been found in Tenerife in the Canary Islands ( Pérez-Íñigo 1972) and Sierra de Alcaraz in mainland

Spain ( Subías and Gill-Martin 1995). According to Pérez-Íñigo (1997), this species prefers pine litter and dry Mediterranean scrublands. Moraza and Peña (2005) found it in many soils covered by herbs, grasses, heath, bush and trees on Tenerife Island (Canary Islands, Spain). In the steppe vegetation of cape Tarhankut in the Crimean peninsula ( Ukraine), this species was most abundant in patches of mosses, and less abundant in patches of grasses, esparto and sedum ( Seniczak et al. 2009). In patches of mosses it achieved a density of 21 individuals per 500 cm 3, and its juveniles make up 27.1% of the population ( Seniczak et al. 2009). In contrast, in steppe bushes this species prefers patches of herbs (Seniczak et al. forthcoming).

Figures

Figure 8. Part of tibia and tarsus I of tritonymph; scale bars 20 µm. (A) Arthrodamaeus reticulatus, paraxial aspect; (B) Gymnodamaeus bicostatus, paraxial aspect; (C) G. bicostatus, fragment of tarsus with solenidia; (D) Jacotella neonominata, paraxial aspect. Explanation of labels in text.

Figure 10. Adult, anogenital region; scale bars 100 µm. (A) Gymnodamaeus bicostatus; (B) Jacotella neonominata. Explanation of labels in text.

Figure 14. Jacotella neonominata, adult, dorsal aspect; scale bar 100 µm. Legs partially drawn. Explanation of labels in text.

Figure 15. Jacotella neonominata, larva, dorsal aspect; scale bar 50 µm. Legs partially drawn. Explanation of labels in text.

Figure 16. Jacotella neonominata, scale bars 50 µm. (A) Anal region of larva; (B) anogenital region of tritonymph. Explanation of labels in text.

Figure 17. Jacotella neonominata, tritonymph, dorsal aspect; scale bar 100 µm. Legs partially drawn. Explanation of labels in text.