Ghilarovus humeridens Krivolutsky, 1966

Akrami, Mohammad Ali & Bayartogtokh, Badamdorj, 2023, The first record of Ghilarovus humeridens Krivolutsky (Acari, Oribatida, Zetomotrichidae) from Iran with a supplementary description, Persian Journal of Acarology 12 (4), pp. 495-504 : 497-502

Ghilarovus humeridens Krivolutsky, 1966 ( Figs. 1–4 )

Diagnosis

Adult – Total length 402–482. Rostrum with slightly protruding median part having four teeth of subequal size and about 10 small lateral dentations on each side. Rostral, lamellar and interlamellar setae long, barbed; bothridial seta filiform, with 9–11 pectinations on one side. Posterior notogastral tectum divided, with overlapping lobes. Notogaster with numerous minute pores scattered irregularly. Notogastral setae thin, acuminate, except c 2 thick, finely barbed, tapered. Humeral sac extending posteriorly almost to level of lyrifissure im. Pyriform organ absent. Custodium long, strongly tapered, extending to base of pedotectum I.

Juveniles – Unknown.

Supplementary description

Measurements – Body length: female (n = 1) 410; males (n = 3) 408 (range 402–416). Notogastral width: female (n = 1) 263; males (n = 2) 260 (249‒271). No differences between females and males in body size.

Integument – Body color light brown to yellowish brown. Body surface finely and densely punctate.

Prodorsum ( Figs. 1A, 1C , 3E ) – Rostrum dentate, median part having four teeth, subequal in size and spacing, about 3 in length, separated from anterolateral margins by deep indentations, and with about 10 pairs of lateral small dentations. Lateral dents more closely adjacent than medial ones. Rostral seta (51‒64) long, acuminate, curved anteromedially; mutual distance 45‒50. Lamellar seta (92‒104) longest prodorsal setae, moderately barbed, extending well beyond rostrum to tip of rostral seta, mutual distance about 58. Interlamellar seta (62‒68) extending beyond insertions of rostral setae, but not reaching rostral tip, mutual distance 79‒83. Exobothridial seta (18‒23) short and fine, weakly barbed, inserted laterally to bothridium, its insertion situated under anterior part of notogaster. Bothridial seta 75‒83 long, directed posterolaterally, with 9‒11 pectinations on one side, each about 7‒10 in length. Bothridium (16 × 18) small, cup-shaped, its posterior half covered by notogaster, mutual distance about 95.

A weakly developed transverse line anteriorly to insertion of lamellar seta present. No pores present on prodorsal surface. Six pairs of relatively large muscle sigillae in dorsosejugal and interbothridial regions, and some smaller ones anterior to each bothridium.

Notogaster ( Figs. 1A, 1C , 3D ) – Notogaster oval, broad anteriorly, conspicuously narrower posteriorly. Posterior margin divided, with lobes overlapping medially, visible in ventral view. Humeral projection accompanied posteriorly by a nearly round triangular projection; humeral seta c 2 45‒55 long, thickened and weakly barbed, tapered (slightly dilated in median part), positioned dorsally on humeral tubercle. Other notogastral setae setiform, thin, acuminate, 16‒22 long. Seta lm positioned medially, in longitudinal alignment with bothridial seta, other setae inserted laterally. Humeral sac (hu) large, about 90 long, sac-like, extending to vicinity of lyrifissure im. Pyriform (pearshaped) organ absent.

Lyrifissure ia not evident; im longest notogastral lyrifissure, as long as 2/3 notogastral setae, situated posterior to humeral sac, lateral of seta lm, aligned transversely. Lyrifissure ip medium-sized, situated anterior to seta h 2; ih and ips short but well developed, situated anterior to seta p 3, isible only in lateral view. Numerous minute notogastral pores scattered irregularly on notogastral surface. Opening of opisthonotal gland (anterolaterally to seta lp) between im and seta lp. Circumgastric sigillar band visible.

Epimeral and lateral podosomal regions ( Figs. 1B, 1C , 2A , 3C ) – Acetabulum IV situated adjacent to acetabulum III. Pedotectum I PdI long. Notogastral lyrifissures ih and ips distinct, short. Epimeral region with numerous muscle sigillae, creating illusion of reticulate pattern. Apodemata sejugal apo.sj and II apoII well developed, aligned obliquely, other apodemes not evident. Epimeral setae relatively long, conspicuously barbed, setal formula 3-1-3-3. 1a (30–40) long and thick, almost reaching insertion of hypostomal seta h, directed anteriorly. 1c (40–48), 3b (37), 3c (27–32), 1b (27), 4c (21–24), 2a, 3a, 4a, 4b (15–18). Custodium strongly tapered, extending to base of PdI. Pedotectum I relatively large, bearing seta 1c, pedotectum II smaller, bearing setae 3b and 3c. Discidium weakly triangular, bearing seta 4c.

Gnathosoma ( Figs. 1B, 1C , 2 ) – Subcapitulum longer than wide (105–115 × 80–86). Hypostomal setae setiform, barbed bilaterally; a (24) shorter, directed medially, seta m (40) and seta h (44) longest, curving anteriorly. Adoral setae or (20–24) setiform, strongly barbed. Palps (length 85–95) with setation 0-2-1-3-9(+ω). Solenidion not attached to acm, straight, pressed to tarsus surface. Chelicera relatively large, Cheliceral length 115–120, with two barbed setae; cha (47) setiform, chb (22) slight swelling distally, penicillate, tapered; fixed and movable digits with few blunt teeth. Trägårdh's organ of chelicerae elongate triangular, with rounded tip and curved mediodistal part.

Anogenital region ( Figs. 1B, 1C , 3A, 3B ) – Genital aperture (39–43 × 37) small, anal aperture (72 × 67–70) nearly rounded. Distance between genital- and anal apertures about twice as long as genital aperture (79–82). Four pairs of genital (g 1-4) (11–14), one pair of aggenital (ag) (9), two pairs of anal (an 1-2) (5–8) and three pairs of adanal (ad 1-3) (4–9) setae, all of them thin, smooth. Aggenital seta inserted more or less at level of posterior genital margin, in longitudinal alignment with epimeral seta 4b. Adanal seta ad 1 inserted at level of posterior anal margin. Adanal lyrifissures iad aligned obliquely at anterolateral corners of anal aperture, anterior to adanal seta ad 3. Ovipositor considerably elongated.

Legs ( Fig. 4 ) – All legs heterotridactylous, median claw shorter, but thicker than lateral claws. Femora I-IV and trochanters III and IV with distinct porose areas p.a. with anteroventral porose area on tibiae I‒IV and posteroventral porose area on tarsi I‒IV. Tibia I triangular with very large dorsodistal projection, while tibia II with relatively smaller dorsodistal projection. Setal and solenidial formula (I to IV): trochanters: 1-1-2-1; femora: 5-5-3-2; genua: 2(1)-2(1)-1(1)-2; tibiae: 4(2)-4(1)- 3(1)-3(1); tarsi: 20(2)-16(2)-15-12; leg setation and solenidia given in Table 1. Leg IV much enlarged. No specialized strong setae on legs and acetabulum not dorsally displaced, so not adapted for jumping. On tarsus I solenidion ω 2 approximately triple as long as solenidion ω 1. Solenidia φ 1 of tibia I and φ of tibia II very long, setiform, located on dorsodistal apophyses. Famulus ε of tarsi I short, blunt-ended. All tarsal setae barbed, setae on ventral side of tarsi I‒IV robustly barbed.

Material examined

Specimens of G. humeridens were collected in two counties in Fars province, southern Iran: Locality 1- Shiraz county, nine specimens, collected by M. Behmanesh, 2.XI.2009: Dasht-e Arjan, soil of oak trees, Quercus sp. ( Fagaceae ) and azarole hawthorn, Crataegus azarolus L. ( Rosaceae ), 29° 34' N, 52° 57' E, 2042 m a.s.l.; Khanezenyan, soil of prickly thrift, Acantholimon sp. ( Plumbaginaceae ), 29° 40' N, 52° 08' E, 1953 m a.s.l.; Qalat, soil of mountain almond, Amygdalus scoparia Spach ( Rosaceae ) on the top of the mountain, 29° 48' N, 52° 18' E, 2431 m a.s.l.; Locality 2- Sepidan county, three specimens, collected by J. Shahvand: Komehr village, soil of cypress trees, Cupressus sp. ( Cupressaceae ), 2.VII.2021, 30° 41' N, 51° 89' E, 2334 m a.s.l.; Ardakan, soil of sweet almound trees, Amygdalus communis L. ( Rosaceae ), 18.IX.2021, 30° 16' N, 51° 58' E, 2299 m a.s.l.

Material deposition

The specimens are deposited in the Acarological Collection of the Department of Plant Protection, School of Agriculture, Shiraz University, Shiraz, Iran.

Ecology

This species has relatively wide distribution in the Palaearctic region and is a typical inhabitant of the soil-litter of various dry forests and mountain soils in the arid environments ( Krivolutsky 1966, 1975; Karppinen et al. 1986; Chen et al. 1992; Wang et al. 2003).

Figures

Figure 1. Ghilarovus humeridens Krivolutsky, 1966, (adult, legs not shown) – A. Dorsal view of body; B. Ventral view of body; C. Lateral view (palpal setae not shown; only some posterolateral setae of notogaster are shown). Scale bar = 50 μm.

Figure 2. Ghilarovus humeridens Krivolutsky, 1966 (adult) – A. Subcapitulum, anterior region of prodorsum, parts of palps and epimeral region; B. Chelicera, right, antiaxial view; C. Palp, left, antiaxial view. Scale bar = 25 μm.

Figure 3. Ghilarovus humeridens Krivolutsky, 1966 (adult) – A. Genital region, showing genital setae and male organ; B. Ovipositor (part of bDp is shown); C. Part of ventral plate, showing pedotecta I and II, discidium and custodium; D. Notogastral seta c2; E. Bothridium, bothridial and exobothridial setae. Scale bar = 25 μm.

Figure 4. Ghilarovus humeridens Krivolutsky, 1966 (adult) – A. Leg I, left, paraxial view, trochanter not illustrated; B. Leg II, right, paraxial view, trochanter not illustrated; C. Leg III, left, antiaxial view; D. Leg IV, right, antiaxial view. Scale bar = 25 µm.