Oribatodes mirabilis Banks, 1895

Ermilov, Sergey G. & Bayartogtokh, Badamdorj, 2024, Contribution to knowledge of the oribatid mite genus Oribatodes (Acari, Oribatida, Cepheusidae), with supplementary descriptions of two species and data on juvenile instars, Zootaxa 5485 (1), pp. 73-91 : 75-81

Oribatodes mirabilis Banks, 1895

( Figs 1–6 )

Material. Nine adults and four nymphs (one deutonymph, three tritonymphs): USA, New York, Onondaga Co., Cicero Game Management Area , 43º08.869'N, 76º02.873'W, sphagnum moss in bog, 15.X.1994 (leg. R. A. Norton) . Five adults: USA, Wisconsin, Kenosha Co., Salem, Silver Lake , sphagnum moss in bog, 23.XI.1978 (leg. W. Suter). Adults were compared indirectly with the type specimen of Nathan Banks (they were compared with specimens that had been previously compared directly to the type; pers. com. Roy A. Norton) .

The material (adults and juvenile instars) is deposited in the collection of the Tyumen State University Museum of Zoology , Tyumen, Russia. All specimens are preserved in 70% solution of ethanol with a drop of glycerol.

Main morphological traits. Adult. Body length: 630–750. Rostrum narrowly triangular. Prolamella present, pair directed anteriorly, separated and close to each other. Rostral and lamellar setae setiform, with short flagellate tip, barbed; interlamellar seta robust, barbed; bothridial seta with long stalk and short, slightly developed head having barbs and short ciliae. Notogastral foveolae rounded, oval or polygonate. Notogastral setae c, la, lm, lp, h 2, h 3, p 2, p 3 setiform, barbed (h 2, h 3 ˃ lp ˃ c, la, lm ˃ p 2 ˃ p 3); h 1, p 1 bacilliform, heavily barbed; dorsal setae inserted on two longitudinal carinae. Leg trochanters III and IV with tooth dorsoanteriorly.

Supplementary description of adult. Measurements. Body length: 630–750; notogastral width: 450–585. Sex not identified.

Integument ( Figs 1A–E ; 5A–D ; 6A, B ). Body color brown to dark brown. Body and legs covered by thick layer of gel-like cerotegument with bacillar and microgranulate inclusions. Surface microgranulate sculpturing; notogaster with large rounded, oval or polygonal foveolae forming typical foveolate-reticulate ornamentation; prodorsum (except rostrum and basal part), lamella, pedotectum I, lateral part of epimere I with medium-sized foveolae; lateral part of body between notogaster and acetabula II, III densely tuberculate; anogenital region with ridges and depressions.

Prodorsum ( Figs 1A, B, D ; 5A, C ; 6A, B ). Rostrum narrowly triangular. Lamellar cusp with small lateral tooth. Translamella absent. Prolamella simple, pair directed anteriorly, separated and close to each other. Transverse convex ridge located between rostral region and prolamellae. Tutorium ridge-like, heavily spinose dorsally. Rostral (67–79) and lamellar (90–101) setae setiform, with short flagellate tip, barbed; interlamellar seta (97–101) robust, barbed; bothridial seta (94–101) with long stalk and short, slightly developed head having barbs and short ciliae; exobothridial seta not observable.

Notogaster ( Figs 1A, D, E ; 5A, C, D ; 6A, B ). Humeral process well defined. One pair of longitudinal carinae beginning from anterior notogastral margin and stretches along the insertions of dorsal setae (well developed between c and la; poorly observed between la and h 2). Notogastral setae (c, la, lm: 60–75; lp: 101–112; h 2, h 3: 131–139; p 2: 56–64; p 3: 49–56) setiform, barbed; h 1 (37–41) and p 1 (49–52) bacilliform, heavily barbed. Opisthonotal gland opening and all lyrifissures distinct (except ia not observable in dorsal view).

Gnathosoma ( Figs 1A, D ; 5B ). Similar to O. reticulatus . Subcapitulum size: 131–135 × 97–101; subcapitular setae (a: 32–37; m: 19–22; h: 28–30) setiform, roughened; both adoral setae (9) setiform, smooth. Palp length: 82–86; postpalpal seta (9) spiniform, smooth. Chelicera length: 131–135; setae (cha: 37–41; chb: 22–24) setiform, barbed.

Epimeral and podosomal regions ( Figs 1C, D ; 5B, C ). All epimeral setae (3c, 4c: 41–45; 1b, 3b, 4a: 26–30; 4b: 22–26; 1c: 19–22; 1a, 2a, 3a: 15–19) setiform, roughened. Discidium elongate triangular, rounded distally. Circumpedal carina originating near posterior margin of acetabulum IV, then curving to approach circumgastric scissure asymptotically.

Anogenital region ( Figs 1C–E ; 5B ). Genital (26–34), aggenital (22–26), anal (19–26), and adanal (22–26) setae setiform, roughened. Adanal lyrifissure distinct.

Legs ( Figs 5B, C ; 6A ). Generally, similar to O. reticulatus .

Description of deuto- and tritonymphs. Measurements. Total length: 465 (deutonymph), 570–615 (tritonymphs); total width: 345 (deutonymph), 435–450 (tritonymphs).

Integument ( Figs 2 , 3A, B ). Body colorless with a yellowish tint. Body surface indistinctly porose covering by gel-like cerotegument with bacillar and tuberculate inclusions. Exuvial scalps foveolate.

Prodorsum ( Fig. 2 ). About 1/3 of gastronotic region (in lateral aspect). Rostrum rounded. Rostral seta (Dn: 67; Tn: 64–75) setiform, barbed, inserted on tubercle; lamellar seta (Dn: more than 140; Tn: more than 170) subflagellate, barbed, inserted on tubercle; interlamellar seta (Dn, Tn: 6) spiniform, smooth, located on tubercle; bothridial seta (Dn: more than 140; Tn: more than 170) subflagellate, barbed; exobothridial seta (Dn: 37; Tn: 41–52) setiform, slightly barbed.

Gastronotic region ( Figs 2 , 3A, B ). Exuvial scalps found in all nymphs, with nine or ten pairs of setae (c 1, c 2, da, dm, dp, la, lm, lp, h 2 in La, Pn; c 1, c 2, c 3, la, lm, lp, h 1, h 2, h 3, p 1 in Dn, Tn); all setae of larval scalp setiform, setae of protonymphal scalp setiform, with short flagellate tip (except simple c 1, c 2), setae of deutonymphal scalp subflagellate (except setiform c 2). Gastronotic setae c 1, c 3, la, lm, lp, h 1, h 2, h 3 p 1 very long (more than 200 in Dn, more than 300 in Tn), flagellate, barbed, often broken; p 2 (Dn: 150; Tn: 205), p 3 (Dn: 82; Tn: 157–165) setiform, with short flagellate tip; c 2 (Dn: 150; Tn: 169–184) setiform, barbed; all setae except p 2, p 3 inserted on large trapezoid apophyses. Opisthonotal gland opening and all cupules distinct in transmitted light.

Gnathosoma. Similar to that of adult.

Epimeral region ( Figs 3A, B ). Epimeral setal formula: Dn: 3-1-2-2; Tn: 3-1-3-3; all setae in Dn (1a, 1c, 2a, 3a: 17–19; others: 26–30) and Tn (1a, 1c, 2a, 3a: 19–22; 1b, 3b: 41–45; others: 30–34) setiform, slightly barbed.

Anogenital region ( Figs 3A, B ). Genital (Dn: 26; Tn: 34–37), aggenital (Dn: 26; Tn: 34–37), anal (Tn: 26–30), and adanal (Dn: 26; Tn: 34–37) setae setiform, slightly barbed. Adanal cupule distinct; anal cupule not observable.

Legs ( Figs 4A–D ). Claw of each leg strong, slightly barbed on dorsal side. Formulas of leg setation and solenidia: Dn: I (0-4-3-4-16) [1-2-2], II (0-4-3-4-13) [1-1-2], III (1-3-2-3-13) [1-1-0], IV (0-2-2-2-12) [0-1-0]; Tn: I (1-4-4-5-18) [1-2-2], II (1-4-4-5-15) [1-1-2], III (2-3-3-4-15) [1-1-0], IV (1-2-3-4-12) [0-1-0]; homology of setae and solenidia indicated in Table 1 .

Note: Roman letters refer to normal setae, Greek letters refer to solenidia (except ɛ—famulus), d φ and d σ— seta and solenidion coupled. One apostrophe (’) marks setae on anterior and double apostrophe (”) setae on posterior side of the given leg segment. Parentheses refer to a pair of setae. * —Leg setation in tritonymph of O. reticulatus unknown.

Figures

FIGURE 1. Oribatodes mirabilis Banks, 1895, adult (gnathosoma and legs not shown): A—dorsal view; B—anterior part of prodorsum, anterodorsal view; C—ventral view; D—right lateral view; E—posterior view. Scale bars 100 μm (A, C–E), 50 μm (B).

FIGURE 2. Oribatodes mirabilis Banks, 1895, tritonymph (some gastronotic setae broken. Scale bar 100 μm.

FIGURE 3. Oribatodes mirabilis Banks, 1895, juvenile instars: A—epimeral and anogenital region of deutonymph, ventral view; B—epimeral and anogenital region of tritonymph, ventral view. Scale bar 100 μm.

FIGURE 4. Oribatodes mirabilis Banks, 1895, tritonymph:A—leg I, right, antiaxial view; B—leg II (tarsus not shown), right, antiaxial view; C—leg III (tarsus not shown), left, antiaxial view; D—leg IV, left, antiaxial view. Scale bar 50 μm.

FIGURE 5. Oribatodes mirabilis Banks, 1895, adult, SEM micrographs (cerotegument partially removed): A—dorsal view; B—ventral view; C—right lateral view; D—notogastral seta h3.

FIGURE 6. Oribatodes mirabilis Banks, 1895, adult, SEM micrographs (cerotegument partially removed): A—anterodorsal view; B—humeral process of notogaster, bothridium, interlamellar and bothridial setae, basal parts of lamella, tutorium and pedotectum I, from right lateral view.