Zygoribatula colemani, Franklin, Elizabeth, 2008

Franklin, Elizabeth, 2008, Zygoribatula colemani sp. nov (Acari, Oribatida, Oribatulidae) from Granite Outcrops in Georgia, USA, with a highly variable translamella, Zootaxa 1847, pp. 34-48 : 35-38

Zygoribatula colemani sp. nov.

Figs. 1–4

Diagnosis. With the characters of Zygoribatula (see Weigmann 2006). Rostral apex tripartite, the central division triangular. Cuticle with a faint foveolate micro-ornamentation. Translamella extremely variable, grading from total absence to forming complete, well-developed ridge. When complete, translamella narrower than lamella. Prodorsal setae ro, le, and in of equal size; mutual distance of pair le less than that of pair in. Setae in shorter than lamellae. Fourteen pairs of smooth notogastral setae, most covered with very thin cerotegument; da shorter than porose area Aa. Porose areas Aa and A1 elongated. Lyrifissure iad immediately anterior to respective anal plate; seta ad3 anterior to iad and longitudinally aligned with it.

Measurements. Medium sized species, adult body length 400–470 (439) µm, width 250–310 (279) µm (N = 16).

Integument ( Figures 1 A–C). Adult yellowish-brown. Cuticle essentially smooth; covered with very faint foveolate micro-ornamentation. Most setae of prodorsum and notogaster covered with thin cerotegument.

Prodorsum ( Figures 1 A, 1C, 2A, 2B, 3). Rostrum tripartite in dorsal view: central division triangular, lateral projections rounded. Prodorsum without prolamella or sublamella, without sublamellar porose area. Lamella uniform in width, without distal cusp; running 2/3 length of prodorsum. Translamella variable, ranging from well developed to entirely absent ( Fig. 3 ); sometimes interrupted medially. When complete, translamella narrower than lamella. Prodorsal setae (except ex) thick, distinctly barbed. Mutual distance of lamellar setae (le) less than that of interlamellar setae (in); le and in shorter than lamella; le inserts in anterior convexity of lamella. Exobothridial seta (ex) short, thinner and smooth. Base of bothridium covered by notogastral margin. Sensilus clavate, with a central translucent clavate head on a medium stalk, faintly barbed.

Notogaster ( Figures 1 A, 1B, 1C). Almost as wide as long, with small, multi-ridged anterolateral shoulders; anterior margin not protruding over prodorsum. Dorsophragmatic apophysis tongue-like, conspicuous; pair separated by apophysis width. Small, elongated humerosejugal porose area present, anterior to shoulder ridges; small, subcircular dorsosejugal porose area situated just lateral to dorsophragmatic apophysis. Fourteen pairs of smooth notogastral setae, most with thin cerotegument. Apart from slightly shorter c1 and p -row, notogastral setae of equal size. Octotaxic system represented by large porose areas; Aa elongated, longer than others, situated medial to setae la; A1 elongated and situated lateral to setae lp; A2 and A3 smaller, more oval. Lyrifissures ia, im, ih, ips and ip present; im relatively long and aligned obliquely on the notogaster.

Ventral Region ( Figure 1 B). Ventral setae smooth. Epimeral setal formula 3–1–3–3. Well-developed pedotecta I and II. Sejugal apodemes and associated epimeral border forming a broad transverse belt immediately anterior to genital plates. Genital opening smaller than anal opening. Epimeral and ano-genital setae short, smooth. Four pairs of genital and one pair of aggenital setae; two pairs of anal and three pairs of adanal setae. Lyrifissure iad immediately anterior to respective anal plate; seta ad3 anterior to iad and longitudinally aligned with it. Postanal porose area elongated, narrow, immediately behind anal plates.

Gnathosoma ( Figures 2 C, 2D). Diarthric subcapitulum with broad rutella and smooth setae. Setal formula of pedipalp (solenidion in parentheses) 0–2–1–3–8(1); femur relatively long, about equal in length to remain- der of appendage, with long, smooth setae. Chelicera robust, cuticle with faint striations; setae cha and chb normal-shaped, setiform, strong and barbed.

Legs ( Figure 4 A, 4B). Pretarsus of all legs hetero-tridactylous, robust, with a strong, well developed median claw and two thin lateral claws; latter bearing small denticles on dorsal surface. Solenidion ω2 of tarsus I longer and thinner than solenidion ω1, both setiform, strong, and distally blunt. Both solenidia on tibia I inserted on common, blunt apophysis; solenidion φ1 of tibia I inserted short distance posterior to φ2. Gena II and III each with setiform solenidion, that of genu I longest. Femora III and IV with rectangular outline in lateral view; that of femora I and II more rounded; femur IV with slight ventral expansion. Small porose areae present ventrally on all tarsi and tibiae; large porose area present anterodorsally on all femora. Setal formulae: leg I, 1–4–3–4–18; leg IV 1–2–2–3–12. Solenidial formula: I, 1–2–2; IV, 0–1–0.

Material examined. 14 adults (holotype female and 13 paratypes) collected from depressions containing shallow soils in granite outcroppings, April 10, 2006, Rocks and Shoals Natural Area (N 33o53’ 15.5”, W 0 83 o20’ 0.60”; elevation 230 m. a.s.l.), Clarke County, Georgia, USA, by D. A. Crossley, Jr. These are the simplest of the outcrop communities identified by Burbanck and Platt (1964), with soils only 1 cm deep. The only vegetation present was the sedum Diamorpha smalli Britt. The holotype and 8 paratypes are deposited in the Georgia Museum of Natural History, Natural History Building, University of Georgia, Athens, GA 30602- 1882. Five paratypes are deposited in the Acarology Laboratory of the Ohio State University.

Etymology. This species is named in honor of Dr. David C. Coleman, Distinguished Research Professor, Institute of Ecology of the University of Georgia, USA, in recognition of his lifetime of research on soil ecology.

Figures

FIGURE 1. Zygoribatula colemani n. sp., adult (legs removed). A, dorsal view (the large oval outlines represent eggs); B, Ventral view (the thin double line passing through ad 3 is part of an internal trachea); C, Lateral view. Scale bar = 100 µm.

FIGURE 2. Zygoribatula colemani n. sp. adult: A, Bothridium and sensillus; B, Tip of rostrum; C, subcapitulum and pedipalp, right half in dorsal view; D, Chelicera, antiaxial aspect. Scale bar = 50 µm.

FIGURE 3. Zygoribatula colemani n. sp. adult: prodorsum of 15 specimens showing variation of translamella ranging from entirely absent (top left) to well developed (bottom right). Interlamellar setae broken in most specimens, represented only by alveoli.

FIGURE 4. Zygoribatula colemani n. sp. adult: A, Leg I (trochanter not included); B, Leg IV. Both in antiaxial aspect. Scale bar = 25 µm.