Basilobelba werneri Mahunka, 1982

Ermilov, Sergey G. & Lindquist, Evert E., 2024, Ontogenetic instars of Basilobelba werneri Mahunka, 1982 (Acari, Oribatida, Basilobelbidae), Zootaxa 5485 (1), pp. 92-105 : 93-103

Basilobelba werneri Mahunka, 1982

( Figs 1–9 )

Supplementary description of adult. Measurements (eight males, 10 females). Body length: 600–690; notogastral width: 435–480. No clear difference between females and males in body size.

Integument ( Figs 4A–D ; 5A–F ). Body color light brown to brown. Body and leg surface with dense microtuberculate sculpturing, covered by thick layer of cerotegument consisting of dense bacillar and tuberculate components forming partially microreticulate ornamentation (well visible in dissected specimens).

Prodorsum ( Figs 1A, B ; 2B ; 4A–D ; 5A, C, D ). Rostrum narrowed, nearly pointed. Rostral region with median, longitudinally elongate bulge. Transverse ridge between lamellar setae. Costula and lateral carina well observable. Transversely elongate tubercle between interlamellar setae. Rostral seta (82–94) slightly thickened, acute, barbed; lamellar (105–112) and interlamellar (64–75) setae thick, narrowed distally, heavily barbed; bothridial seta (315– 332) setiform, barbed; bothridium with longitudinal depression medially; exobothridial seta (22–26) setiform, slightly barbed.

Notogaster and nymphal exuvial scalps ( Figs 1A–C ; 2A–E ; 4A–D ; 5A, C ). Dorsosejugal furrow narrow and deep; anterior notogastral margin straight. Anterior part of notogaster depressed. Eight pairs of setiform, slightly barbed notogastral setae present in typical pattern (la, lm, h 2, h 3: 13–15; h 1, p 1, p 2, p 3: 22–26); sometimes alveolus of seta c and extra seta in p -row (p *) developed; setae h 1 and p 1 located close to each other. Opisthonotal gland opening and all lyrifissures well observable in transmitted light. Nymphal exuvial scalps reticulate, with nine pairs (frequently broken) of setiform, roughened setae (c 1, c 2, la, lm, lp, h 1, h 2, h 3, p 1: 15–26, except c 1 and c 2 up to 34 in tritonymphal exuvial scalp); tritonymphal scalp with typical attachment arches (span distance larger than distance between bothridia) bearing setae c 1 and c 2. Apical part of cornicle in protonymphal exuvial scalp brush-like distally versus smooth in deuto- and tritonymphal exuvial scalps.

Gnathosoma ( Figs 3A–C ; 5B ). Subcapitulum size: 165–169 × 112–120; subcapitular setae (a: 49–52; m, h: 64–71) setiform, barbed; two pairs of adoral setae (15) setiform, roughened. Palp length: 94–101; formula: 0-2- 1-3-8(+ω); seta lt” absent; solenidion long, bacilliform; postpalpal seta (9) spiniform, smooth. Chelicera length: 150–161; setae (cha: 45–49; chb: 30–34) setiform, barbed.

Epimeral region ( Figs 2A, B ; 5B ). Epimeral setal formula: 3-1-3-3; setae (1a, 2a, 3a: 52–64; 1b, 1c, 4b: 71–75; 3b, 3c, 4a, 4c: 86–97) setiform, barbed; setae 3b and 3c located at the base of small tubercle.

Anogenital region ( Figs 1C ; 2A, B ; 5B ). Six pairs of genital (52–64), three pairs of aggenital (52–64), two pairs of anal (37–45), and five pairs of adanal (52–64) setae setiform, barbed; all adanal setae in ventromarginal position. Adanal lyrifissure close and parallel to anal plate.

Legs ( Figs 3D–G ; 4A–D ; 5A, B, E, F ). Claw of all legs comparatively thin, slightly roughened dorsally, with slight tubercle ventrobasally. Formulas of leg setation and solenidia: I (1-5-4-5-20) [1-2-2], II (1-5-4-5-14) [1-1-2], III (2-3-2-4-13) [1-1-0], IV (1-3-2-4-10) [0-1-0]; homology of setae and solenidia indicated in Table 1 . Famulus medium-sized, rod-like; setae p’, p” and s on tarsus I eupathidial; setae p’ and p” on tarsi II–III absent; all or some setae on leg segments thick, narrowed distally, heavily barbed; solenidion ω 2 on tarsus I medium-sized, rod-like versus other solenidia short or medium-sized, slightly bacilliform (in addition, φ 2 on tibia I slightly dilated mediodistally).

Description of juvenile instars. Measurements. Total length of larva: 390, 405 (n=2), protonymph: 425–450 (n=3), deutonymph: 510–525 (n=6), tritonymph: 570–600 (n=4). Total width of larva: 210, 225 (n=2), protonymph: 270–300 (n=3), deutonymph: 345–360 (n=6), tritonymph: 375–420 (n=4).

Integument ( Figs 9A–D ). Body colorless to light yellowish. Body and leg surface with slight microtuberculate and striate sculpturing, covered by thick layer of cerotegument consisting of dense bacillar and tuberculate components forming partially microreticulate ornamentation; dorsosejugal region under interbothridial tectum densely microfoveolate.

Prodorsum ( Figs 6A, C ; 7A–C ; 9A–D ). Relatively short, about 2/3 of gastronotic region. Rostrum pointed. Dorsolateral region with arcuate carina (most likely, vestigial costula in adult); lateral side with thin carina (most likely, vestigial lateral carina in adult). Interbothridial region with narrow transverse tectum covering partially dorsosejugal furrow. Rostral seta (LA: 37–41; PN: 49–52; DN: 56–60; TN: 56–64) slightly thickened, acute, barbed, inserted on distinct tubercle; lamellar seta (LA: 52–56; PN: 64–71; DN: 71–79; TN: 79–94) thickened, acute, heavily barbed, inserted on distinct tubercle; interlamellar and exobothridial setae (LA: 26–30; PN: 30–34; DN: 34–37; TN: 34–41) setiform, slightly barbed; bothridial seta (LA: 131–142; PN: 150–161; DN: 184–210; TN: 210–232) with long, sparsely barbed stalk and shorter, slightly thickened distal part bearing numerous short cilia; bothridium with longitudinal depression medially.

Gastronotic region ( Figs 6A–C ; 7A–C, G–I ; 9A, B ). Nymphal instars with typical bent cornicle in medioposterior part. Tritonymphal instar with median tubercle. Larva with 11 (dp absent), nymphal instars with 12 (da, dm and dp absent) pairs of setae. Length of gastronotic setae: LA: c 1, h 3: 26–30, c 2: 15–19, c 3: 13–15, da: 37–41, dm: 52–60, la, lm, lp, h 1, h 2: 101–120; PN: c 1, h 1: 26–34, c 2: 19, c 3: 13–15, la, lm, lp: 26–30, p 1, h 2, h 3: 19–22, p 2, p 3: 13–15; DN: c 1, h 1: 30–34, c 2: 19–22, c 3: 15, la, lm, lp: 26–30, p 1, h 2, h 3: 19–22, p 2, p 3: 15–19; TN: c 1, h 1: 30–34, c 2: 22, c 3: 17–19, la, lm, lp: 26–30, p 1, p 2, p 3, h 2, h 3: 19–22. In larval instar, setae c 1, da and dm slightly thickened, acute, barbed, located on porose sclerites; c 2, c 3 and h 3 setiform, slightly barbed; la, lm, lp, h 1, and h 2 thick, narrowed distally, heavily barbed. In nymphal instar, all setae setiform, slightly barbed. Opisthonotal gland opening and all cupules distinct.

Gnathosoma ( Figs 7E–F ). Subcapitulum size: LA: 82–86 × 64–67; PN: 105–109 × 75–82; DN: 124–127 × 90– 97; TN: 146–154 × 97–105; length of subcapitular seta a: LA: 24–28; PN: 34–37; DN: 36–45; TN: 49–52; length of subcapitular seta m: LA: 24–28; PN: 34–37; DN: 41–49; TN: 52–56; length of subcapitular seta h: LA: 19–22; PN: 30–34; DN: 34–41; TN: 41–49; a and m setiform, barbed; h narrowly phylliform, narrowed distally; posterolateral tectum of subcapitular mentum well developed; length of adoral setae: LA, PN: 5; DN, TN: 7; both adoral setae setiform, smooth. Palp length: LA: 49; PN: 60–64; DN: 64–71; TN: 79–82; palp formula in LA: 0-1-1-3-8(+ω); palp formula in PN, DN, TN: 0-2-1-3-8(+ω); length of postpalpal seta: LA: 4; PN: 5; DN, TN: 7. Chelicera length: LA: 82–86; PN: 105–109; DN: 109–116; TN: 123–139; length of cha: LA: 30; PN: 30–34; DN: 34–36; TN: 41–49; length of chb: LA: 19; PN: 19–22; DN: 22–26; TN: 26–30.

Epimeral region ( Figs 6B, C ; 7G–I ). Setal formulas for epimeres: larva: 3-1-2 (1c as typical scale covering Claparède’s organ); protonymph 3-1-2-1; deutonymph 3-1-3-2, tritonymph 3-1-3-3. Length of setae: LA: 1a, 2a, 3a: 15–19, 1b, 3b: 19–22; PN: 1a, 2a, 3a: 11–15, 1c: 7; 1b, 3b, 4a: 19–22; DN, TN: 1a, 2a, 3a: 11–15, 1c: 7–9; 1b, 3b, 3c, 4a, 4b: 19–22; setae 1a, 2a and 3a slightly phylliform, narrowed distally, 1c simple, others setiform, roughened.

Anogenital region ( Figs 6B, C ; 7G–I ). Ontogeny of genital (PN, DN: 15–19; TN: 19–22), aggenital (DN: 15–19; TN: 19–26), anal (TN: 15–22), and adanal (DN: 15–19; TN: 19–22) setal formulas, larva to tritonymph: 0- 1-3-5, 0-0-1-3, 0-0-0-2, 0-0-3-3, respectively; all setae setiform, roughened; small round porose area at the base of adanal setae. Adanal cupule distinct; anal cupule not observed.

Legs ( Figs 8A–F ; 9A, B ). Claw of all legs comparatively thin, slightly roughened dorsally. Formulas of leg setation and solenidia: larva I (0-2-3-4-16) [1-1-1], II (0-2-3-3-13) [1-1-1], III (0-2-2-2-13) [1-1-0]; protonymph I (1-3-3-4-16) [1-1-2], II (1-3-3-3-13) [1-1-1], III (1-3-2-2-13) [1-1-0], IV (0-0-0-0-7) [0-0-0]; deutonymph I (1-4-3- 4-16) [1-2-2], II (1-4-3-4-13) [1-1-2], III (2-3-2-3-13) [1-1-0], IV (1-2-2-2-12) [0-1-0]; tritonymph I (1-5-4-5-16) [1-2-2], II (1-5-4-5-13) [1-1-2], III (2-3-2-4-13) [1-1-0], IV (1-3-2-4-12) [0-1-0]; homology of setae and solenidia indicated in Table 1 . Famulus medium-sized, rod-like; all or some setae on leg segments thick, narrowed distally, heavily barbed; solenidion ω 2 on tarsus I medium-sized, rod-like versus other solenidia short or medium-sized, slightly bacilliform (in addition, φ 2 on tibia I slightly dilated mediodistally).

Figures

FIGURE 1. Basilobelba werneri Mahunka, 1982, adult: A—dorsal view (larval, proto- and deutonymphal exuvial scalps omitted); B—notogaster and basal part of prodorsum, dorsal view (exuvial scalps omitted); C—posterior view (exuvial scalps omitted). Scale bar 100 μm.

FIGURE 2. Basilobelba werneri Mahunka, 1982, adult: A—ventral view (gnathosoma and legs omitted); B—right lateral view (exuvial scalps, gnathosoma and legs omitted); C—protonymphal exuvial scalp (setae broken), anterior view; D—protonymphal exuvial scalp (some setae broken), posterior view; E—deuto- and tritonymphal exuvial scalps (some setae broken), posterolateral view. Scale bar 100 μm, A, B; C–E to same scale.

FIGURE 3. Basilobelba werneri Mahunka, 1982, adult: A—subcapitulum, ventral view; B—palp, right, antiaxial view; C— chelicera, left, paraxial view; D—leg I, right, antiaxial view; E—leg II, right, antiaxial view; F—leg III, left, antiaxial view; G—leg IV, left, antiaxial view. Scale bars 20 μm (A–C), 50 μm (D–G).

FIGURE 4. Basilobelba werneri Mahunka, 1982, adult, SEM micrographs: A—dorsal view (larval, proto- and deutonymphal exuvial scalps omitted); B—dorsoanterior view (larval, proto- and deutonymphal exuvial scalps omitted; tritonymphal scalp shifted); C—right lateral view (larval exuvial scalp omitted); D—right dorsolateral view (larval, proto- and deutonymphal exuvial scalps omitted; tritonymphal scalp shifted).

FIGURE 5. Basilobelba werneri Mahunka, 1982, adult, SEM micrographs: A—dorsoanterior view (exuvial scalps omitted); B—ventral view (larval, proto- and deutonymphal exuvial scalps omitted; tritonymphal scalp shifted); C—part of dorsosejugal region (some seta broken); D—surface and cerotegument on prodorsum; E—distal part of leg I (some seta broken), right, antiaxial view; G—distal part of leg II (some seta broken), right, paraxial view.

FIGURE 6. Basilobelba werneri Mahunka, 1982, larva: A—dorsal view (legs omitted); B—ventral view (legs omitted); C— right lateral view (legs omitted). Scale bar 50 μm.

FIGURE 7. Basilobelba werneri Mahunka, 1982, juvenile instars: A—protonymph, dorsal view (exuvial scalps omitted); B— deutonymph, dorsal view (exuvial scalps omitted); C—tritonymph, dorsal view (exuvial scalps omitted); D—subcapitulum (lips with adoral setae omitted), ventral view; E—palp, right, paraxial view; F—chelicera, left, paraxial view; G—protonymph, ventral view (gnathosoma and legs except trochanters omitted); H—deutonymph, ventral view (gnathosoma and legs except trochanters omitted); I—tritonymph, ventral view (gnathosoma and legs except trochanters omitted). Scale bars 100 μm (A–C, G–I), 50 μm (D–F).

FIGURE 8. Basilobelba werneri Mahunka, 1982, juvenile instars: A—leg I of larva, right, antiaxial view; B—leg III of larva, left, antiaxial view; C—leg I of deutonymph, right, antiaxial view; D—leg II of deutonymph, right, antiaxial view; E—leg III of deutonymph, left, antiaxial view; F—leg IV of deutonymph, right, antiaxial view. Scale bar 50 μm, the following groups to same scale: A, B; C–F.

FIGURE 9. Basilobelba werneri Mahunka, 1982, deutonymph, SEM micrographs: A, B—dorsal view (larval exuvial scalp omitted); C—basal part of prodorsum, right part; D—distal part of bothridial seta.