Dyobelba tectopediosa Jacot 1938

Dyobelba tectopediosa (Jacot, 1938) (Figs. 1-4, 5 A, B) Oribata tectopediosa Jacot, 1938: 10. Dyobelba tectopediosa: Norton, 1978: 616. Diagnosis. Prodorsum with apophysis P well developed; tubercle Ba well developed; alveolate sculpturing distributed in dorsal and lateral patches. Sensillus very long, thin, smooth, flagellate, with shepherd’s crook bend. Notogastral setae directed in radial pattern, medium long, thin, mostly smooth, with basal vane; spinae adnatae of moderate size. Tectum of podocephalic fossa strongly developed, produced laterally as strong triangular tooth underneath trochanter I; ventral enantiophyses V and S well developed; all epimeral setae inserted on conspicuous small tubercles; discidium well developed. Setae d on genua I–III nearly as long as respective coupled solenidia σ; solenidia ϕ of tibiae II and III longer than coupled setae d. Description. Dimensions. Adult body length 336–375 (354) Μm; length of notogaster 220–241 (233) Μm; width of notogaster 204–214 (210) Μm. Integument. Adult yellowish brown. Surface of body and legs with thick cerotegument having granular to short columnar excrescences (Fig. 4 A). Cuticle microtuberculate throughout, conspicuously so on rostrum, in regions of alveolate sculpturing as noted below, and on bulbs of leg femora. Most setae of prodorsum and notogaster with thin cerotegument basally and medially. Prodorsum (Figs. 1 A, C, 2 A, 4B). Rostrum with dark transverse band at level of setae ro in transmitted light (Fig. 1 C), due to contour of transverse groove and underlying rostrophragma. With pair of central swellings at level of legs I (above sigillae for cheliceral retractor muscles). Prodorsal enantiophyses A absent. Postbothridial tubercle Ba well developed, nearly triangular in shape, its tip usually rounded, but sometimes acute (Fig. 1 A). Dorsal end of acetabular tectum I with small, posteriorly directed tooth. Propodolateral apophysis (P) strongly developed, directed anterolaterad. Cuticle alveolate in following regions: on central prodorsal swellings; on propodolateral apophysis, becoming weak in lateral region of epimeres I, II; in dorsosejugal furrow medial to tubercles Ba; on all acetabular tecta, least developed on III, IV, strongest on I, where alveolar field may merge with respective dorsal region. Prodorsal setae smooth or with sparse weak barbs: rostral seta (ro) medium long, thin; lamellar seta (le) similar, but slightly longer than ro; interlamellar seta (in) conspicuously longer, but thinner than le, directed posterolaterad; exobothridial seta (ex) thinner and shorter than ro. Sensillus (ss) very long, thin, smooth, finely attenuate and flagellate, but with fixed shepherd’s crook bend. Bothridium typical of family, irregularly funnel-shaped, directed posterolaterad. Notogaster (Figs. 1 A, 2A, 4A, B). Oval, slightly longer than wide. Spinae adnatae (sa) thin, moderate length, in dorsal view nearly straight, directed anteriorly or anteromedially, and slightly ventrad; mutual distance about that of setal pair c2 or slightly greater. Notogastral setae of c, l and h rows of medium length, directed radially. Setae appear thin, smooth in dorsal aspect; in lateral aspect curved in basal half or third, with small, hyaline vane spanning basal curvature and often one barb dorsally, rarely two (Figs. 4 D, 5A, B). Setae of p -row thin, smooth, directed laterally. Gnathosoma. Subcapitular mentum slightly wider than long. Mentum with pair of transverse carinae posterior to hypostomal setae (Fig. 1 B); microtuberculate, many tubercles elongated and fused to form transverse striae. Subcapitular setae h, m and a medium long, thin, smooth. Cheliceral setae cha and chb finely barbed. Epimeral region (Fig. 1 B, D). Tectum of podocephalic fossa strongly developed, laterally produced as strong, sharp tooth (t) directed underneath trochanter I (seen on edge in Fig. 1 B). Ventrosejugal tubercles Va and Vp well developed, large, subtriangular, nearly rounded at tip. Parastigmatic tubercles Sa and Sp subtriangular, Sa elongate, longer than Sp. Discidium (di) nearly triangular, blunt at tip. Epimeral setae medium long, thin, smooth; all setae situated on distinct small tubercle. Ano - genital region (Figs. 1 B, 2A). Ano-genital setae medium long, smooth. Adanal lyrifissure (iad) situated obliquely, at level slightly anterior to anal seta an2. Genital plates almost smooth, with sparse microtubercles. Legs (Figs. 2 C,D, 3). Structure of legs I–IV mostly typical for genus, sub-moniliform. Femora I and II with small, rounded to acute proximoventral spur. Trochanter and femur IV subequal in length; each with distal tectum rounded, not projecting. Setae d on genua I-III nearly as long as their associated solenidia σ; solenidia ϕ of tibiae II and III slightly longer than their associated setae d. Solenidia ϕ1 of tibia I and ω1 of tarsus I situated on distinct dorsal projections (Fig. 2 D). Material examined. North Carolina. Buncombe Co., Bent Creek Experiment Station, A. P. Jacot, col., 15 July 1935, one cotype from oak litter; three topotypes with same data (prepared by Jacot but without type-designation). Same, L.J. Metz, col., April 1974, six (one male, five females), ex. mixed hardwood and grass litter. Same, R. A. Norton, col., 15 May 1976, 10 ex. mixed Quercus forest, with some Cornus. Buncombe Co., Asheville-Brevard Rd. (Rt. 191), ca 6 miles south of Ashville, R. A. Norton, col., 14 August 1974, three (one male, two females) ex. Pinus rigida litter on slope; seven (six males, one female) from Ilex litter in P. r i g i d a forest. Haywood Co., Davenport Gap on Pigeon River, Rt. 327, near Waterville, R. A. Norton, col., 15 May 1975, seven (six males, one female) ex. mosses on steep rocky slope. Tennessee. Sevier Co., Newfound Gap Road, 5 miles south of Gatlinsburg, R. A. Norton, col., 15 May 1976, one (female) ex. litter in hardwood forest (Liriodendron, Populus, Acer, Betula, some Tsuga). Alabama. Marshall Co., near Merrill Cave, 1 mile north of Guntersville Dam, S. Peck, col., 26 June 1967, two (females) ex. mixed leaf–log litter. Specimens prepared by A. P. Jacot are mounted in Canada-balsam (cotype from U.S. National Museum collection; undesignated topotypes in RAN collection). Other examined specimens are preserved in alcohol in the NUMU (2) and RAN (remainder) collections. Remarks. Dyobelba tectopediosa has been found in the following states and counties of the eastern USA: North Carolina (Buncombe, Haywood Co.), Tennessee (Sevier Co.) and Alabama (Marshall Co). The species appears to be restricted to the middle and southern parts of the Appalachian region. Some specimens were collected from grass litter and moss, but most were from litter in a wide variety of forest types, including Pinus, Quercus, Liriodendron, Acer, Betula, and Tsuga. Though the original description by Jacot (1938) was short and not accompanied by illustration, the main characters were presented. He noted that the propodolateral apophyses (tectopedia II) were strongly “pockmarked”, and other parts of the prodorsum (“cephalothorax”) were “areolate.” He also noted the flagellate sensillus (“pseudostigmatic organ”) with shepherd’s crook bend. However, in the original description he mentioned that trochanter III had one long seta; instead, this segment has two setae as in all known species of Dyobelba (verified in cotype). Dyobelba tectopediosa is unique among known species of the tectopediosa group in having notogastral setae of the c, l and h rows that in dorsal view are radially directed, smooth and nearly straight. In other known species these setae are directed longitudinally, curved and noticeably barbed to some degree.

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