Parabelbella inaequipes ( Banks, 1947 )

Ermilov, Sergey G. & Ryabinin, Nikolay A., 2020, Сontribution to the knowledge of Parabelbella (Acari, Oribatida, Damaeidae): description of two new species from Russia and the U. S. A., redescription of P. inaequipes (Banks, 1947) and a key to known species, Zootaxa 4860 (3), pp. 352-374 : 367

Parabelbella inaequipes ( Banks, 1947)

( Figs 13–17 )

Material examined. Eight specimens (three males and five females): U.S.A., Virginia, Page County, Skyline Drive , Stony Man overlook, red oak ( Quercus rubra ), litter, 18.V.1974 (collected by R. A. Norton)

Material deposition. Eight specimens are deposited in the collection of the TSUMZ. All specimens are preserved in ethanol with a drop of glycerol.

Diagnosis. Body size: 381–415 × 232–249. Propodolateral apophysis and all prodorsobasal tubercles absent. Rostral and lamellar setae long, setiform, barbed. Interlamellar seta long, stiff, erect, barbed. Bothridial seta very long, flagellate, smooth. Dorsal notogastral setae long, slightly stiff, elongate crescent, with short, setiform tip, roughened, p 1 – p 3 short, setiform, roughened. Setae c 1 directed anteriad. Distance c 1 – c 1 slightly shorter than that of c 1 – c 2. Distance lm–lp little longer than that of la–lm and lp–h 3. Parastigmatic apophysis Sa thorn-like, Sp tuberclelike. Epimeral, median and anterior pair of ventrosejugal tubercles absent. Posterior pair of ventrosejugal tubercles present, simple. Discidium triangular. Epimeral and anogenital setae setiform, roughened, seta 3b inserted on Vp. Leg femur III with four setae.

Description. Measurements. Body length: 381–415 (eight specimens); notogaster width: 232–249 (eight specimens). No clear differences between males and females in body size.

Integument ( Figs 16 A–D). Body color light brown to yellowish. Surface of body and legs sculptured (microtuberculate), partially covered by layer of cerotegument, which is represented by tuberculate and bacillar (sometimes also filamentous) structures.

Prodorsum ( Figs 13A, C ; 16A, C ; 17A, B ). Rostrum rounded. Prodorsal tectum, propodolateral apophysis, anterobothridial ridge and all prodorsobasal tubercles absent. Muscle sigillae in median part of the interbothridial region not observed. Rostral (53–57) and lamellar (61–69) setae setiform, barbed, directed anteromediad. Interlamellar seta (36–41) stiff, erect, barbed, directed posteriad. Bothridial seta (221–229) flagellate, smooth. Exobothridial seta (32–36) setiform, thin, slightly barbed.

Notogaster ( Figs 13 A–C; 16A, C; 17A, B). Oval. Exuvial scalps absent. Eleven pairs of notogastral setae of light color, roughened, c 1, c 2, (61–65), la, lm, lp (69–73), h 1 – h 3 (49–53) slightly stiff, elongate crescent, with short, setiform tip p 1 (32–41), p 2, p 3 (20–24) setiform, roughened. Dorsal notogastral setae inserted in two parallel rows, c 1 and c 2 directed anteriad,, other setae directed posteriad. Mutual distance between setae c 1 – c 1 slightly shorter than that of c 1 – c 2. Distance between insertions of seta lm–lp little longer than that of la–lm and lp–h 3. All notogastral lyrifissures, opisthonotal gland opening and circumgastric scissure distinct. Circumgastric sigillar band poorly visible.

Gnathosoma ( Fig. 16B ). Subcapitulum longer than wide (94–98 × 69–73). Three pairs of subcapitular setae (a, 24; m, 32; h, 28) setiform, slightly barbed. Two pairs of adoral setae (8–12) setiform, thin, roughened. Palp (82–86) with setation 0-2-1-3-9(+ω). Solenidion of palptarsus bacilliform, appressed to palptarsal surface. Postpalpal seta (6) spiniform, smooth. Chelicera (94–98) with two setiform setae, cha (28) barbed, chb (16) shortly ciliate unilaterally in mediodistal part. Trägårdh’s organ of chelicera elongate triangular.

Lateral podosomal and epimeral and regions ( Figs 13B, C ; 16B, C ; 17A , C–E). Parastigmatic apophysis Sa thorn-like, elongate triangular, Sp tubercle-like. Both pairs of epimeral tubercles and one pair of median tubercles absent. Anterior pair of ventrosejugal tubercles absent, posterior pair present, simple. Discidium triangular. Epimere I without median hollow (ring-like internal structure in light microscope). Epimeral setal formula 3-1-3-4. Epimeral setae (1a, 1c, 2a, 3a, 20–28; 1b, 3b, 3c, 4a, 4b, 4c, 4d, 28–36) setiform, roughened, seta 3b inserted on ventrosejugal tubercle Vp.

Anogenital region ( Figs 13B, C ; 16B, C ; 17A ). Six pairs of genital, one pair of aggenital, two pairs of anal and three pairs of adanal setae similar in length (24–28), setiform, roughened. Adanal lyrifissure diagonal, located close to anal plate. Adanal seta ad 3 located posterolaterally to adanal lyrifissure.

Legs ( Figs 14A, B ; 15A, B ; 16 A–C; 17A). Legs I and III similar to body in length approximately, legs II shorter than body length, leg IV longer than body length ( Table 4). Claw of all legs comparatively small, thin, smooth. Dorsoparaxial porose area on femora I–IV and on trochanters III and IV well visible. Formulas of leg setation and solenidia: I (1-7-4-4-20) [1-2-2], II (1-6-4-4-17) [1-1-2], III (2-4-3-3-17) [1-1-0], IV (1-4-3-3-14) [0-1-0]; homologies of setae and solenidia indicated in Table 2. Solenidion and coupled seta on genua I-III similar in length approximately.

Figures

FIGURE 13. Parabelbella inaequipes (Banks, 1947), adult: A—dorsal view (legs not shown); B—ventral view (legs not shown); C—lateral view (gnathosoma and legs not shown). Scale bar 100 μm.

FIGURE 14. Parabelbella inaequipes (Banks, 1947), adult: A—leg I, right, antiaxial view; B—leg II, right, antiaxial view. Scale bar 50 μm.

FIGURE 15. Parabelbella inaequipes (Banks, 1947), adult: A—leg III, left, antiaxial view; B—leg IV, left, antiaxial view. Scale bar 50 μm.

FIGURE 16. Parabelbella inaequipes (Banks, 1947), adult, SEM micrographs: A—dorsal view; B—ventral view; C—lateral view; D—cerotegument on notogaster. Scale bar 100 μm (A–C), 10 μm (D).

FIGURE 17. Parabelbella inaequipes (Banks, 1947), adult, microscope images: A—lateral view; B—interbothridial region and anterior part of notogaster, dorsal view; C—ventrosejugal region anterior to genital aperture, ventral view; D—posterior ventrosejugal tubercle Vp, ventral view; E—parastigmatic apophyses Sa and Sp and discidium, ventral view.