Zetorchestes krisperi, Kolesnikov & Leonov, 2021

Kolesnikov, Vasiliy B. & Leonov, Vladislav D., 2021, Zetorchestes krisperi sp. nov. (Acari: Oribatida: Zetorchestidae) from Vietnam with juvenile morphology and identification key to known species of the genus, Zootaxa 5057 (4), pp. 545-561 : 546-556

Zetorchestes krisperi sp. nov.

( Figs 1–7 )

Diagnosis. Adult. Body size: 445–450 × 330–340. Cuticle with small granules and wrinkles. Wrinkles located in anal area, along notogastral setae c 2 – h 3, in anterior part of notogaster, but not in medial region. Dorsosejugal suture indicated only by row of granules. Rostral tubercles not wide, spaced apart from each other at distance of at least half of their width. Interlamellar setae long (50–55), pair touching distally, phylliform (5–6). Lamellar surface is irregular, prolamella and sublamella present, translamella absent. Nine pairs of notogastral setae (c 1 and h 1 absent), all setae phylliform (5–7) (ps narrower than rest—2–3). Notogastral tubercle present. Median pore on notogaster absent. One pair anal and adanal setae. Trochanter IV without setae.

Tritonymph. Integument of gastronotal area with wrinkled cerotegument; 7 pairs of gastronotal setae (c 1 and h 1 absent); one pair of minute anal and adanal setae; with transverse fold between posterior part of lamellar lines; setae v” present on tibia IV.

Description of adult. Measurements. Body length 450 (holotype), 445 (paratype); body width 340 (holotype), 330 (paratype).

Integument ( Figs 1–4 , 7A, B ). Body color dark brown. Prodorsum, notogaster, ventral sides and subcapitulum surface granulate (diameter of granules—1–2). Along insertions of notogastral setae row (c 2 – h 3) stretches an almost continuous row of wrinkles. Isolated wrinkles are present on anterior and lateral parts of notogaster and around setae c 2 – h 3, but do not enter medial part of notogaster. Medial region of epimeras I–II with irregular reticulate pattern of large cells different in form and size. Cuticula of epimeras III region (anterior to genital opening) with reticulate pattern of smaller polygonal cells. Anal region with isolated wrinkles. Prodorsum and epimeral region without wrinkles. Genital, anal plates and legs with micro-furrows. Cerotegument ( Figs 1–3A, B , 4D , 7A–C ) granulate, covering the whole body.

Prodorsum ( Figs 1 , 3A , 7A ). Rostrum with small protrusion. Rostral setae (87–91×5–6) long, with forked tips, inserted on tubercles. Rostral tubercles ( Figs 1 , 7A ) isolated, not wide (height 10–11, width 17–20), separated from each other by more than half their width. Lamellar surface is irregular, distally with tubercle bearing lamellar seta. Prolamella present, narrow. Sublamella present as isolated elevation lateral to lamella. Lamellar seta (50–55) setiform, smooth. Tutorium simple, with small rounded protrusion anteriorly. Interlamellar setae (50–55×5–6) long, phylliform, slightly barbed, pair touching distally. Exobothridial seta (4–5) short, setiform. Bothridial seta (80–90) clavate, distinctly barbed. Bothridium with two projections on posterior margin. Small costula extends ventrad from bothridium.

Notogaster ( Figs 1 , 3A, B , 7A, B ). Dorsosejugal suture not present, represented only by row of granules. Notogaster wide, tapering towards posterior; with unpaired medial tubercle (nt) between level of setal pairs h 2 and ps 1 (height 18–20, width 45–50). Notogaster with 9 pairs of setae, c 1 and h 1 absent. Setae c 2 (35–40×5–6), la (46– 50×6–7), lm (50–53×6–7), lp (45–47×6–7), h 3 (35–40×5–6) and h 2 (36–38×4–5) phylliform, slightly barbed. Setae c 2 and la nearly touch distally, setae lm reaches base of la, setae lp, h 3, h 2 nearly reach insertion of previous seta. Seta la not displaced laterally. Seta ps 1 (25–27×3) slightly thickened, smooth, located under notogastral tubercle, their insertions nearly adjacent (mutual distance equal to alveolar diameter). Setae ps 2 (20×2) and ps 3 (15–17×2) slightly thickened, smooth. Median pore absent. Opisthonotal gland opening and all lyrifissures distinct; gla located lateral to lp; ia located lateral to c 2; im longest, located lateral to lm; ip long, located lateral to notogastral tubercle; ih located lateral to h 3, ips located lateral to h 2.

Gnathosoma ( Figs 3C–E ). Subcapitulum size: 115–120×105–110. Three pairs of subcapitular setae setiform, a (16–17), m (22–24) and h (11–12). Two pairs of adoral setae (16–18) setiform. Length of palp: 95–100. Femur of palp with wavy cuticle. Palpal setation 0-2-1-3-9(+ω). Solenidion narrows towards end, pressed to surface of tarsus in basal half. Length of chelicera: 132–136. Two cheliceral setae (cha, 45; chb, 25) setiform, barbed. Trägårdh’s organ short (34), elongate triangular. Cheliceral cuticle finely porose distal to attachment of cheliceral frame. On paraxial side, distal from cha, small cuticle spine is visible.

Epimeral and lateral regions ( Figs 2 , 3A , 7B ). Epimeral setal formula: 3-1-3-3; setae (5–10) setiform, thin, smooth. Pedotectum I and II well expressed, rounded distally in ventral aspect. Discidium poorly developed, rounded ( Fig. 7B ). Lateral costula kj (80) strongly developed, lateral costulae kp (80–85) and kp′ (20–22) distinct, connected anteriorly, kp″ only weakly developed. Lateral costula kl′ (40) descends to discidium, kl″ (30) short, posterior from acetabulum IV.

Epimeral costulae ke′ (80) begin at podotecta II and reach level of front edge of genital opening. They slightly shifted medially in the last two thirds of length (after joining with ke″). Short ke″ (40) joins to ke′ behind the coxatrochanter acetabulum with sharp angle.

Anogenital region ( Figs 2 , 3A, B ). Six pairs of genital (10–12), one pair of aggenital (9–10), one pair of anal (5) and one pair of adanal (10) setae setiform, thin, smooth. Genital setae g 1 – g 3 close to medial edge of genital plate, setae g 4 – g 6 shifted to medial part of genital plate. Preanal sclerite with two arms. Anal setae located closer to anterior part of plates. Anal plates with longitudinal costulae. Present two pairs longitudinal ventral costulae k 1 (40–50) and k 3 (70–80) and unpair transverse costula k 2 (120). Adanal lyrifissure iad situated obliquely.

Legs ( Figs 4 , 7C ). Claws short, smooth. Porose area present, but poorly visible on all femora and trochanters III, IV. Femur II with strong ventral keel having scalloped edge. Formulas of leg setation and solenidia: I (1-5-2-4-19) [1-2-3], II (1-5-2-4-15) [1-1-2], III (2-3-1-3-14) [1-1-0], IV (0-2-1-3-12) [0-1-0]; homologies of setae and solenidia indicated in Table 1 . Famulus on tarsus I bacilliform, slightly broadened distally, inserted between solenidia ω 1 and ω 2. Solenidia ω 1 and ω 2 on tarsus II bacilliform, other solenidia setiform. Proral setae (p) on tarsus I with rounded tip (eupathidial), other proral setae branched. Seta it″ on tarsus I–III absent. Setae (u) on tarsus I–III expanded, those on tarsus IV hypertrophic lanceolate. Seta pv″ on tarsus III strong, toothed. Setae v′ on tibia IV and (pv) on tarsus IV hypertrophic lanceolate. Seta ft″ on tarsus I minute, coupled with ω 1. Setae ft′ and ft″ on tarsus I–III far apart.

Description of tritonymph.

Measurements. Body length 430; body width 300.

Integument ( Figs 5 , 6D , 7D–J ). Body color brown. Cuticle of lateral, and anogenital areas plicate, except for dorsal side of body (semitransparent and smooth under exuvia; in anterior part of gastronotic area, well-pigmented, with single transverse fold separating gastronotic setae of row c. Cuticle with small surface pits. Legs with microfurrows. Cerotegument granular, covering whole body. On nymphal exuvia wrinkled cerotegument present in anterior part ( Figs 5A, D , 7J ).

Note: Roman letters refer to normal setae, Greek letters to solenidia (except ɛ = famulus). Single prime (′) marks setae on the anterior and double prime (″)—setae on the posterior side of a leg segment. Parentheses refer to a pair of setae. Setae are listed only for the stage in which they first appear.

Prodorsum ( Figs 5A, C , 7D ). Rostrum broadly rounded. Prodorsum with well-sclerotized ridges (lamellae) running posteriorly from lamellar setae, connected at base by transverse ridge. Rostral seta (78×5) long, forked distally, inserted on small tubercle (length 8, width 11), mutual distance of this tubercle at least half of their width. Lamellar (24) and interlamellar setae (19) setiform, smooth. Exobothridial seta (2) short, fine, smooth. Bothridial seta (80) clavate, distinctly barbed. Bothridium with two projections posteriorly.

Gastronotum ( Figs 5 , 7D–F, J ). Cone-shaped form. Dorsosejugal groove distinct, straight. With 7 (c 2, la, lm, lp, ps 1 – ps 3) pairs of smooth gastronotic setae. Setae c 2, la, lm and lp short (9–11), curved, ps 1 – ps 3 very short (5), visible only under oil immersion objective. Setae c 1 absent (c 1 also absent from all exuvia). Setae h 1 and h 2 absent on tritonymph (at other stages unknown). Setae da, dm and dp present only on larval exuvium. Exuvia shifted toward posterior part of gastronotic area and turned to ventral side of body. Larval exuvium plicate, nymphal exuvia with single well-developed transverse fold separating setae of row c 1 ( Figs 5D, E , 7J ). Lyrifissures ia and im hardly visible among folds of integument, ip, ih, ips present. Gland opening gla distinct, situated lateral to anal slit.

Gnathosoma. Subcapitulum size: 90 × 75. Three pairs of subcapitular setae setiform, a (10), m (18) and h (6). Two pairs of adoral setae (9) setiform. Length of palp: 76. Femur of palp with wavy cuticle. Palpal setation 0-2-1-3- 9(+ω). Solenidion narrows towards end, pressed to surface of palptarsi mediobasally. Length of chelicera: 120. Two cheliceral setae (cha, 33; chb, 18) setiform, barbed. Trägårdh’s organ short (28), elongate triangular.

Epimeral regions ( Figs 5B, C , 7E, F ). Epimeral setal formula: 3-1-3-3. All setae short and smooth. Apodemes II, sejugal and acetabulum III with weakly developed respiratory channels.

Anogenital region ( Figs 5B, C ). Five pairs of genital (10–15), one pair of aggenital (9), one pair of anal (1) and one pair of adanal (2) setae setiform, thin, smooth; anal and adanal setae minute. Adanal lyrifissure iad oriented obliquely.

Legs ( Figs 6 , 7G–H ). Claws short, smooth. All femurs and trochanters III, IV with small ventral scalloped keel. Formulas of leg setation and solenidia: I (0-4-2-4-16) [1-2-3], II (0-4-2-3-13) [1-1-2], III (1-3-1-2-13) [1-1-0], IV (0-2-1-2-12) [0-1-0]; homologies of setae and solenidia indicated in Table 1 . Famulus on tarsus I bacilliform, slightly broadened distally, inserted between solenidia ω 1 and ω 2. Solenidia ω 1 and ω 2 on tarsus II bacilliform, other solenidia setiform. Proral setae (p) on tarsus I rounded distally (eupathidial), other proral setae branched. Seta v″ present on tibia I. Setae (u) on tarsus I–III expanded, IV lanceolate. Seta pv″ on tarsus III and v′ on tibia IV strong, toothed. Setae (pv) on tarsus IV lanceolate. Seta ft″ on tarsus I minute, coupled with ω 1. Setae ft′ and ft″ on tarsus I–III far apart.

Type material. Holotype (female) and two paratypes (male and tritonymph) at coordinates 12.1854º N, 108.6789º E. All are stored in Zoological Institute, Russian Academy of Sciences, St. Petersburg, Russia ( ZISP), preserved in a 70% solution of ethanol with a drop of glycerol.

Etymology. The species is named after the acarologist Dr. Günther Krisper (Institute of Zoology, University of Graz, Austria), who made a great contribution to the study of mites of family Zetorchestidae .

Comparisons. The new species belongs to a group of Zetorchestes species having phylliform notogastral setae and lacking seta c 1, which also includes Z. transvaalensis , Z. novaguineanus Krisper, 1987 , Z. phylliferus , Z. saltator , Z. aokii Krisper, 1987 , Z. vanderhammeni Krisper, 1987 , Z. schusteri . It differs from Z. aokii in spread rostral tubercles ( Z. aokii with wide and close-shifted rostral tubercles—the distance between them is noticeably less than half the width of the tubercles), slightly expanded setae ps ( Z. aokii with thin setae), closely shifted ps 1 (at Z. aokii the distance between them is wider), prodorsum and medial part of notogaster without wrinkles ( Z. aokii with wrinkles on prodorsum and whole notogaster), long interlamellar setae (touch their ends) (at Z. aokii these setae do not touch their ends). New species differs from Z. novaguineanus in absence of h 1, phylliform ps ( Z. novaguineanus with thin setae) and width of notogastral (6–7) and interlamellar setae (5–6) ( Z. novaguineanus has these setae 9–12 wide). New species differs from Z. phylliferus in absence of h 1, median pore on notogaster, not detectable dorsosejugal suture ( Z. phylliferus with distinct dorsosejugal suture), presence of one pair anal and adanal setae ( Z. phylliferus with two pairs anal and adanal setae). The new species differs from Z. saltator in the absence of h 1 and presence of one pair anal and adanal setae ( Z. saltator with two pairs anal and adanal setae), normal setae la arrangement (in the same row with the rest of notogastral setae) (at Z. saltator with laterally displaced setae la). New species differs from Z. schusteri in absence of h 1, phylliform interlamellar setae ( Z. schusteri with slightly phylliform in), spread rostral tubercles ( Z. schusteri with wide and close-shifted rostral tubercles—the distance between them is noticeably less than half the width of the tubercles), presence of prolamella, not visible dorsosejugal suture ( Z. schusteri with partially discernible dorsosejugal suture). The new species differs from Z. transvaalensis in absence of h 1, median pore on notogaster, noticeably phylliform notogastral and interlamellar setae ( Z. transvaalensis with these setae narrowly phylliform), lamellar surface is irregular ( Z. transvaalensis with smooth lamella). The new species differs from Z. vanderhammeni in absence of h 1, spread rostral tubercles ( Z. vanderhammeni has wide and close-shifted rostral tubercles—the distance between them is noticeably less than half of the width of the tubercles).

The tritonymph of Z. krisperi differs from that of Z. micronychus (see Ermilov & Kolesnikov 2013) in having wrinkled cerotegument on the anterior gastronotum ( Z. micronychus with polygonal cerotegument), the absence of setae c 1 and h 1 (present in Z. micronychus ), the presence of one pair of anal and adanal setae ( Z. micronychus with two pairs), the presence of a transverse fold between posterior part of lamellae (absent in Z. micronychus ), and the presence of seta v″ on tibia I (absent in Z. micronychus ).

Figures

FIGURE 1. Zetorchestes krisperi sp. nov., adult: dorsal view (legs not illustrated).

FIGURE 2. Zetorchestes krisperi sp. nov., adult: ventral view (gnathosoma and legs not illustrated).

FIGURE 3. Zetorchestes krisperi sp. nov., adult: A—lateral view (gnathosoma and legs not illustrated); B—posterior view; C—subcapitulum, ventral view; D—chelicera, left, antiaxial view; E—palp, left, antiaxial view.

FIGURE 4. Zetorchestes krisperi sp. nov., adult:A—leg I, without trochanter, left, antiaxial view; B—leg II, without trochant- er, left, antiaxial view; C—leg III, left, antiaxial view; D—leg IV, left, antiaxial view.

FIGURE 5. Zetorchestes krisperi sp. nov., tritonymph: A—dorsal view (exuviae and legs not illustrated); B—ventral view (gnathosoma and legs not illustrated); C—lateral view (exuvia, gnathosoma and legs not illustrated); D—protonymphal and deutonymphal exuvia, dorsal view; E—larval exuvium, dorsal view (posterior part is torn).

FIGURE 6. Zetorchestes krisperi sp. nov., tritonymph: A—leg I, without trochanter, right, antiaxial view; B—leg II, without trochanter, right, antiaxial view; C—leg III, right, antiaxial view; D—leg IV, right, antiaxial view.

FIGURE 7. Zetorchestes krisperi sp. nov., adult (A, B, C), tritonymph (D-J), light microscope images: A—prodorsum and dorsosejugal region, dorsal view; B—partial lateral view of the hysterosoma and trochanter IV, lateral view; C—leg IV (part tibia and part tarsus), left, antiaxial view; D—prodorsum and dorsosejugal region, dorsal view; E—epimeral I-III region, part, ventral view; F—region of setae 4b, ventral view; G—leg IV (part tibia and part tarsus), right, antiaxial view; H—leg I (tibia and part tarsus), right, antiaxial view; I—leg II (tibia and part tarsus), right, antiaxial view; J—anterior part of deutonymphal exuvium, dorsal view.

Tables

TABLE 1. Leg setation and solenidia of tritonymph and adult Zetorchestes krisperi sp. nov.

Leg		Tr	Fe	Ge	Ti	Ta
I	tritonymph	–	d. l′. bv″. v	(l). σ	(l). (v). φ 1, φ 2	(ft). (tc). (p). (u). (a). s. (pv). (pl). ɛ. ω 1.
						ω 2. ω 3
	adult	v′	l″	–	–	it′. v′. l″
II	tritonymph	–	d. l′. bv″. v	(l). σ	(l). v′. φ	(ft). (tc). (p). (u). (a). s. (pv). ω 1. ω 2
	adult	v′	l″	–	v″	it′. l″
III	tritonymph	l’	d. ev′. l’	l′. σ	l′. v′. φ	(ft). (tc). (p). (u). (a). s. (pv)
	adult	v′	–	–	v″	it′
IV	tritonymph	–	d. ev′	d	l′. v′. φ	ft″. (tc). (p). (u). (a). s. (pv)
	adult	–	–	–	v″	–