Dyobelba dindali, Bayartogtokh, Badamdorj & Norton, Roy A., 2007

Bayartogtokh, Badamdorj & Norton, Roy A., 2007, The Dyobelba tectopediosa species-group (Acari: Oribatida: Damaeidae) from the Southeastern USA, with a key to world species of Dyobelba and notes on their distribution, Zootaxa 1591, pp. 39-66 : 50-57

Dyobelba dindali sp. nov.

(Figs.5G–I, 8–10)

Diagnosis. Prodorsum with propodolateral apophysis P weakly developed; tubercles Aa and Ba well developed; alveolate sculpturing present in dorsal and lateral patches. Sensillus thin, smooth, flagellate, with shepherd’s crook bend. Notogastral setae c1 and c2 directed anteriorly, l and h rows directed posteriorly, slightly thickened in middle, gently curved, conspicuously barbed on outer curvature, with small proximal vane on inner curvature; spinae adnatae small. Tectum of podocephalic fossa projected as triangular tooth under trochanter I; ventral enantiophyses V and S well developed; all epimeral setae on conspicuous small tubercles; discidium well developed. Setae d on genua I–III slightly longer and thicker than respective coupled solenidia σ; solenidia ϕ of tibiae II and III shorter than their coupled setae d.

Description. Adult: Dimensions. Body length 304–333 (318) Μm; length of notogaster 221–243 (231) Μm; width of notogaster 196–220 (208) Μm.

Integument. Body yellowish brown. Surface of body and legs with thick granular cerotegument. Microtuberculate throughout, conspicuous on rostrum, bothridial region, in areas of alveolate sculpturing as noted below, and on basal leg segments. All setae of prodorsum and notogaster with thin cerotegument, at least basally and medially.

Prodorsum ( Figs. 8 A, C, 9C). Rostrum with dark transverse band at level of seta ro in transmitted light, 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). Dorsal end of acetabular tectum I with small, posteriorly directed tooth (lt). Prodorsal tubercle Aa well developed, Ap absent; postbothridial tubercle Ba nearly triangular in shape, its tip usually rounded, but sometimes acute. Propodolateral apophysis weakly developed, not noticeably projected anteriorly. Alveolate sculpturing in following regions: anterolaterally and on prodorsal swellings ( Fig. 8 A, 9C); on propodolateral apophyses extending to lateral region of epimeres I, II; in sejugal furrow between tubercles Ba; on discidium and all acetabular tecta, that on acetabulum I continuous with dorsal patches. Rostral and lamellar setae mostly smooth, with sparse barbs at base; interlamellar seta thin, smooth, length about half their mutual distance, directed straight posteriorly over edge of notogaster; exobothridial seta thin, smooth, curved, shorter than in; sensillus long, thin, smooth, flagellate, with distal shepherd’s crook bend (Fig. 9D). Bothridium typical of family, irregularly funnel-shaped, directed posterolaterad.

Notogaster ( Figs. 8 A, C, 9A). Oval, slightly longer than wide. Spinae adnatae small, thin, directed anteroventrally. Notogastral setae of c, l and h rows slightly thickened in middle, distal to hyaline base; gently curved, conspicuously barbed laterally and on outer curvature (Figs. 5G, 9B), with small proximal vane on inner curvature; c1 and c2 directed anteriorly, l and h rows directed posteriorly. Setae of p row thin, smooth or with sparse small barbs, directed laterally.

Gnathosoma . Subcapitular mentum slightly wider than long. Mentum with pair of oblique to transverse carinae posterior to setae h; surface mostly with granular microtubercles, posteriorly with transverse striae. Subcapitular setae h, m and a medium long, thin, smooth. Cheliceral setae cha and chb smooth.

Epimeral region ( Figs 8 B, C). Tectum of podocephalic fossa projected as triangular tooth under trochanter I (seen only on edge in Fig. 8 B); medial end of tectum often with inconspicuous tooth. Ventrosejugal tubercles Va and Vp well developed, large subtriangular, rounded at tip. Parastigmatic tubercles Sa and Sp subtriangular; Sa much larger than Sp. Discidium nearly triangular, rounded at tip. Epimeral setae medium long, thin, smooth; all situated on distinct small tubercles.

Ano-genital region ( Figs. 8 B, C). Ano-genital setae medium long, smooth. Adanal lyrifissure situated obliquely, at about the same level as seta an2. Anal and genital plates with granular microtubercles.

Legs ( Fig. 8 D; Table 1). Structure and setation of legs I–IV mostly typical for genus, sub-moniliform. Trochanter and femur IV subequal in length. Distal tectum of trochanters III and IV not projected, but rounded. Femora I and II with distinct ridges almost circumferentially surrounding base, near articulation with trochanter, like poorly developed retrotectum (Figs. 5H, I). Setae d of genua I–III slightly longer and thicker than respective coupled solenidia σ; solenidia ϕ of tibiae II and III conspicuously shorter than respective coupled setae d.

FIGURES. 5G, 9B. Dyobelba dindali sp. nov. adult, scanning electron micrographs. A, dorsal view. B, notogastral seta c 1. C, prodorsum, dorsal aspect. D, sensillus (ss). Scale bars: A (100 µm), B (5 µm), C–D (20 µm).

Ontogeny (detail measurements from average-sized specimen of respective instars)

Dimensions (all from slide-mounted specimens). Total length of: larva (La, n=7) 165–194 (mean 177) μm; protonymph (Pn; n=2) 204–233 (mean 218) μm; deutonymph (Dn; n= 9) 223–262 (mean 249) μm; tritonymph (Tn; n=4) 281–320 (mean 296) μm.

Integument. Colorless. Cerotegument granular in all instars, covering entire body, most leg setae and solenidia and prodorsal setae, especially conspicuous on entire length of flagellate sensillus; conspicuous on gastronotic seta h1 of nymphs, but rarely seen on other dorsal setae. Granules of nymphs slightly larger (most 1.5–2 μm diameter in Tn) dorsally and more widely spaced (1–4 diameters apart); ventral granules smaller (1– 1.5μm in Tn) and more dense (mostly 1–2 diameters apart).

Prodorsum. Setae le, ex (ca. 20 μm in La, 35 in Tn) finely attenuate, smooth or with few barbs; ro similar but slightly longer (ca 28 μm in La, 50 in Tn) and sub-flagellate. Pairs ro and le arranged in shallow arch; mutual distance of ro 1/3 that of ro in La, half that of ro in Tn. Seta in posterodorsally directed; flagellate, smooth or with 1–2 small barbs in La (ca 50 μm); short (20 μm in Tn), smooth, blunt and only slightly tapered in nymphs, typical of family (Figs. 10A, B). Sensillus similar in all immatures: smooth, long (ca 115 μm in La, 200 μm in Tn), flagellate; proximal half stiff, nearly straight and tapered, distal half threadlike, flexible and undulating; cerotegument thickest distally.

Troch-anter Femur Genu Tibia Tarsus Leg I

Larva - d, bv” d*, (l), σ d, (l), v’, φ 1 (ft), (pl), (pv), (tc), (a), (u), (p), s, e, ω 1 Protonymph - - - - ω 2 Deutonymph v’ (l) v’ v”, φ 2 - Tritonymph - v 1” - - (it) Adult - v 1’, v 2” - d lost (v) Leg II

Larva - d, bv” d*, (l), σ d, l’, v’, φ (ft), (pv), (tc), (a), (u), (p), s, ω 1 Protonymph - - - - - *genu seta d of larval legs is minute, visible only under good observational conditions.

Gastronotic region. Body elliptical to almost rectangular in larva, oval in nymphs. Exuvial attachment cornicle k of nymphs (20 μm in Tn) straight little tapered distally (Fig. 10D). Opisthonotal gland and all normal cupules in positions typical of genus and family ( Norton 1978). Gastronotic setae inserted on isolated sclerotized tubercles, except in nymphs tubercles of pairs c1 and h1 each respectively connected on inconspicuous medial sclerite. Larval setae (except h3) all finely attenuate to subflagellate, with fine flexible tips, but mostly dimorphic (Fig. 10C): c1, c2, da, dm, dp, lp large, dark brown, heavily barbed on outer curvature; c3, la, lm, h2 small, colorless, essentially smooth; h1 intermediate in form, brown, with noticeable small barbs; h3 highly regressed to minute spine (2 μm). Setae c1 (70 μm) and dorsocentrals (da, dm, dp, 75–80 μm) arched posteriorly, mutual distance of pairs 9, 12, 30, 10 μm, respectively. Seta lp longest (120–150 μm, fine tip often broken), diverging at ca 60-degrees. Seta c2 (70 μm) arched laterally. Setae c3 (20 μm), la (40 μm), lm (35 μm) FIGURE 10. Photomicrographs. A-F, Dyobelba dindali sp. nov. immatures. A, interlamellar seta (in) of larva, mediolateral aspect (base of notogastral seta c1 to left, sensillus in background). B, same, tritonymph. C, dorsocentral region of larval gastronotum, anterior at top. D, cornicle k of tritonymph, anterior at top. E, tarsus I of tritonymph, dorsolateral aspect of proximal region; optical section showing inconspicuous famulus (e) inserted in cup-like depression (arrowhead points to large internal “root” of famulus). F, broken fecal pellet in slide-mounted larva, showing uniform fungal spore contents. G, Dyobelba granulata sp. nov. adult, optical section of crop filled with fragments of pigmented fungal hyphae. (A-E differential interference illumination; F, G brightfield). Scale bars: A, C (10 µm), B, D-G (5 µm). Fig. 10D is combined manually from 2 layers.

arched posteriorly; h1 (50 μm) almost straight, diverging. Nymphal setae also finely attenuate to subflagellate, also with wide range of size. Setae c1, c2, la, lm, lp large, brown, arching posterolaterally around exuvial scalps; barbs less dense than in larva, especially on more posterior setae; respective lengths in Tn: 120, 145, 140, 120, 120 μm. Seta c3 small (20 μm in Tn), colorless. Pair h1 inserted on adjacent tubercles; longest body setae (ca 320 μm in 300 μm long Tn), brown, smooth, straight except for flagellate tip, slightly diverging at ca 10-degrees. Setae h2 (60 μm in Tn) and h3 (110 μm) much smaller, smooth, inserted ventrolaterally. One Pn with c1 doubled on right side (so three setae present on medial sclerite).

Ventral region. Setation typical for genus. Setal formulae for epimeres (I–IV): La 2-1-2, Pn 3-1-2-1, Dn 3- 1-2-2, Tn 3-1-3-3. Seta 3c (not included in formula) of larva with typical scale-form, closely covering Claparède’s organ. Genital setation (Pn–Tn): 1-3-5. Aggenital seta formed in Dn.

Gnathosoma . Typical of genus. Second palp-femur seta formed in Pn.

Legs. Overall form typical of genus. Usual ontogeny of setae and solenidia given in Table 1. No variation seen among 14 legs of La or four of Pn. Of 18 Dn legs examined, one had formed v1 ” on femur I; two lacked l ” of femur II; one formed v’ on genu IV, one lacked d from genu IV; one lacked v’ from tibia IV. Of 12 Tn legs examined, two had formed v1 ’ on femur I; three formed v ” on femur II. Most setae smooth or weakly barbed; ventral setae of tarsi with long, conspicuous barbs. Larva with genu seta d of all legs minute, inconspicuous, coupled with ceratiform solenidion σ which curves ventrodistad around posterior face of segment; genu seta d normal in nymphs, about twice length of erect σ. Tibial seta d of normal form, closely coupled with respective solenidion: equal in length to ceratiform φ on leg II, slightly longer than ceratiform φ on III; d about quarter length of flagellate (tactile) φ1 on leg I in larva, becoming about third its length in Tn; φ of deutonymphal tibia IV subflagellate, twice length of coupled seta d. Larval tarsal solenidia ω I ceratiform on leg I, reaching distad to level of antelateral setae; ω I on leg II thinner and shorter; protonymphal tarsus I solenidion ω2 piliform, slightly longer than seta ft ”. Deutonymphal tibia II solenidion φ2 narrowly ceratiform, as long as segment width; tarsus II solenidion ω2 similar, two-thirds size of ω1. Famulus sunken in sclerotized cup in all instars; non-emergent in larva, very slightly emergent in nymphs; with thin, sclerotized, rodlike internal extension directed proximally about 1.5 times length of famulus (Fig. 10E). Proral setae (p) appear eupathidial in all instars; subunginal seta of tarsus I normal and proximal to setal pair (a) in immatures, becoming eupathidial and distal to pair (a) only in adult; no other setae are eupathidial.

Material examined. Holotype (unsexed adult): Tennessee, Sevier Co., Rt 441, just S of state line, col. R. A. Norton, 14 August 1974, ex. litter under yellow birch and rhododendron on hillside. Paratypes (all adults). 3 with same data as holotype. Tennessee: Sevier Co., Rt 73, 2 miles west from junction with Rt 441, 39 (22 males, 17 females) ex. mixed forest litter with pines (pitch, table mountain), oak, red maple, holly, col. R. A. Norton, 14 August 1974. North Carolina: Haywood Co., Davenport Gap on Pigeon River, Rt. 327, near Waterville, seven (four males, three females) ex. mosses on steep rocky slope, col. R. A. Norton, 15 May 1975; Buncombe Co., Horse Trough Ridge Overlook, three (one male and two females) ex. litter in mixed hardwood slope forest (red oak, sugar maple, shingle oak), col. R. A. Norton, 15 May 1976; Macon Co., Otto, Coweeta Hydrologic Laboratory, three (unsexed) ex. Pinus strobus litter, col. D.L. Dindal, 25 May 1973. Alabama: Lee Co., near Auburn, 21 (14 males, seven females) ex. litter in pine (loblolly and shortleaf) and hardwood (oak, sweet gum) forests, col. R. A. Norton, 7 November 1975. Georgia: Clarke Co., Athens, five (three males, two females ex. pine litter, col. D. Maas, 6 April 1972. Paratypes are distributed among the FMNH (5), CNC (5) NUMU (2) and RAN (the remainder) collections. All but seven slide-mounted paratypes are in alcohol.

Immatures (all in RAN collection) were obtained from a laboratory culture initiated with several adults collected from Sevier Co., Tennessee. A cultured fungus, Trichoderma sp., was provided as food. Spores seemed preferred, as almost nothing else was observed in food or fecal boli (Fig. 10F).

Remarks. Dyobelba dindali sp. nov. is the most widespread member of the tectopediosa group. It has been found in the following states and counties: North Carolina (Buncombe, Haywood Co.), Alabama (Lee Co.), Tennessee (Sevier Co.), and Georgia (Clarke Co.). This species appears to be restricted to the middle and southern Appalachian region in the Eastern US. While found in moss, most collections are from forest litter of various types, including pines (pitch, loblolly, shortleaf, table mountain), oaks (red, shingle), maple (sugar, red), yellow birch, sweet gum and holly.

Adults of D. dindali are distinguishable from others in the tectopediosa species-group in having the combination of: 1) longitudinally-directed notogastral setae that are barbed but not unusually wide; 2) a flagellate sensillus with shepherd’s crook bend; 3) continuous alveolation fully across the prodorsum at mid-level; 4) the presence of prodorsal tubercle Aa. It is most similar to D. granulata sp. nov., from which it can be distinguished by having thinner notogastral setae and more extensive prodorsal alveolation.

Etymology. This species is named in honor of Prof. Daniel L. Dindal (retired), who first collected this species and was the doctoral advisor of the junior author. His superb teaching and enthusiasm for soil biology influenced the lives and careers of many students.

Figures

FIGURE 8. Dyobelba dindali sp. nov., adult. A, dorsal view. B, ventral view. C, lateral view. D, leg I (right, antiaxial aspect). (Legs removed from C, only bases shown in A, B).