Eupterotegaeus nortoni, Ermilov, 2024

Ermilov, Sergey G., 2024, Ontogenetic instars of the oribatid mite Eupterotegaeus nortoni sp. nov. (Acari, Oribatida, Cepheusidae) from U. S. A., Zootaxa 5485 (1), pp. 49-61 : 50-59

Eupterotegaeus nortoni sp. nov.

( Figs 1–6 )

Diagnosis. Adult. Body length: 615–630. Body surface with microtuberculate sculpturing; centrodorsal part of notogaster sparsely foveolate. Rostral and interlamellar regions with medium-sized tooth each. Lamellar cusps well separated, narrowed and slightly serrated mediodistally, without toothlike process. Rostral and lamellar setae setiform, slightly swollen basally, roughened; ro short, located on tubercle, le medium-sized; interlamellar seta short, setiform, slightly swollen basally, slightly roughened; bothridial seta medium-sized, with elongate, flattened, rounded apically, slightly or well developed, barbed head. Interbothridial region with two tubercles. Ten pairs of notogastral setae short, setiform, slightly swollen basally, slightly roughened, located on distinct tubercles; c shorter and thinner than others. Enantiophysis on epimere 4 well developed. Leg trochanters III and IV with tooth dorsoanteriorly.

Description of adult. Measurements. Body length: 615 (holotype, female), 615–630 (11 female paratypes); notogastral width: 420 (holotype), 390–420 (paratypes).

Integument ( Figs 1A–D ; 3A, C–G ). Body color brown to dark brown. Body and legs covered by thick layer of cerotegument; its internal layer uniform, netlike reticulate (mostly hexagonal; Fig. 3D ), but the outer layer gel-like with microtubercular and bacillar structures. Surface microtuberculate sculpturing ( Fig. 3G ). Centrodorsal part of notogaster, partially lamella, tutorium, lateral side of prodorsum, region near anal aperture, anterior part of epimere I foveolate; notogastral foveolae medium-sized (up to 11), sparsely located.

Prodorsum ( Figs 1A–C ; 2A ; 3A–D, F ). Rostrum rounded. Rostral region with strong, erect tooth (26–30). Lamellar cusps well separated, narrowed, sometimes slightly serrated mediodistally, without toothlike process; lamellae connected medially with strong, erect interlamellar tooth (26–30). Translamella absent. Tutorium with triangular cusp. Rostral (22–26) and lamellar (52–60) setae setiform, slightly swollen basally, roughened, directed medially; ro inserted on distinct tubercle; interlamellar seta (15) setiform, thin, erect, slightly swollen basally, slightly roughened; bothridial seta (82–90) with long stalk and short, elongate, flattened, rounded apically, slightly or well developed, barbed head. Exobothridial seta not observed. Interbothridial region with two tubercles located close to each other. Postbothridial region with tubercle.

Notogaster ( Figs 1A–D ; 3A, C, D, F, G ). Humeral process well developed, pointed. Notogaster with band-like depression that circularly border convex central region. Ten pairs of notogastral setae present, all (c: 15; p 2, p 3: 19; others: 22–24) setiform, thin, erect, slightly swollen basally, slightly roughened, inserted on distinct tubercles; c thinner than others. Opisthonotal gland opening and all lyrifissures distinct.

Gnathosoma ( Figs 2B–D ). Subcapitulum size: 139–143 × 79–86; subcapitular (a: 22–26; m, h: 19–22) and adoral (7–11) setae setiform, slightly roughened. Palp length: 79–82; postpalpal seta (7) spiniform, smooth. Chelicera length: 135–143; setae (cha: 32–34; chb: 26) setiform, barbed.

Epimeral and podosomal regions ( Figs 1B, C ; 3E, F ). Epimeral setae 3c, 4c (45–56) setiform, slightly swollen basally, roughened; 1a, 2a, 3a, 1c (13–15), 1b, 3b, 4a, 4b (22–26) setiform, thin, erect, slightly swollen basally, slightly roughened; 4a located at the base of tubercle. Enantiophysis on epimere 4 well developed, represented by simple anterior tubercle and triangular posterior tubercle. Basal part of pedotectum I with strong tooth. Discidium triangular, pointed.

Anogenital region ( Figs 1B–D ; 3E, F ). Genital (15–19), aggenital (19–22), anal (19–22), and adanal (19–22) setae setiform, thin, erect, slightly swollen basally, slightly roughened. Adanal lyrifissure distinct.

Legs ( Figs 2E–H ; 3E, F ). Heterotridactylous; all claws slightly barbed on dorsal side. Trochanters III and IV with tooth dorsoanteriorly. Formulas of leg setation and solenidia: I (1-4-3-4-20) [1-2-2], II (1-4-3-4-16) [1-1-2], III (2-3-2-3-15) [1-1-0], IV (1-2-3-3-12) [0-1-0]; homology of setae and solenidia indicated in Table 1 . Famulus short, slightly swollen and blunt distally, located between solenidion ω 1 and seta ft”; seta s eupathidial; solenidia ω 1 and ω 2 on tarsi I, II medium-sized, bacilliform; solenidia φ 1 on tibia I and σ on genua I long, subflagellate; other solenidia medium-sized, rod-like.

Description of juvenile instars. Measurements. Total length of larva: 285 (n=1), protonymph: 330–390 (n=3), deutonymph: 405–465 (n=2), tritonymph: 495–585 (n=3). Total width of larva: 150, protonymph: 165–210, deutonymph: 240–285, tritonymph: 350–375.

Integument ( Figs 5B–F ; 6A, B, D ). Body colorless (LA) to light yellowish (PN, DN, TN). Body surface indistinctly porose and partially covered by gel-like and sparsely microtuberculate cerotegument; additionally, epimeral and anogenital region partially folded. Exuvial scalps foveolate.

Prodorsum ( Figs 4A–C ; 6A, B, D ). About 1/2 (in larva and protonymph) of gastronotic region. Rostrum broadly rounded. Centrodorsal region with two longitudinal carinae connected by transverse carina. Rostral seta (LA: 30; PN: 30–34; DN: 34–41; TN: 45–52) phylliform, slightly narrowed and rounded distally, slightly barbed, inserted on tubercle in LA versus narrowly phylliform, pointed, slightly barbed, inserted on tubercle in PN, DN, TN; lamellar seta (LA: 22) phylliform, slightly narrowed and rounded distally, slightly barbed, inserted on tubercle in LA versus very broad, reticulate, slightly barbed, inserted on tubercle in PN, DN, TN; interlamellar seta (LA: 22; PN: 15–19; DN: 22; TN: 26) phylliform, slightly narrowed and rounded distally, slightly barbed, inserted on tubercle in LA versus setiform, erect, slightly barbed, inserted on tubercle in PN, DN, TN; bothridial seta (LA: 82; PN: 112– 116; DN: 124–130; TN: 142–146) thickened, indistinctly dilated mediodistally, narrowed distally, densely barbed; exobothridial seta (LA: 4; PN: 4; DN: 6; TN: 7–11) setiform, roughened, inserted on small (LA) or large (PN, DN, TN) tubercle.

Gastronotic region ( Figs 4A–D ; 5E, F ; 6A–D ). With slight apophysis in posterior part in LA and PN. Centrodorsal region with strong tubercle ( Fig. 4D ; performing the function of holding exuvial scalps of previous instars) in PN, DN, TN. Twelve pairs of gastronotic setae in all instars. Length of gastronotic setae (except broadly phylliform): LA: c 1: 56, c 2: 30, da: 82, dm: 90, dp: 101, h 1: 61, h 2: 22, h 3: 13; PN: c 1: 15, h 1: 52, p 1: 22, p 2: 19–22, p 3: 15; DN: c 1: 15, h 1: 56, p 2: 30–37, p 3: 19–22; TN: c 1: 15, h 1: 60, p 2: 37–45, p 3: 22–30. In LA, setae c 1, c 2, da, dm, dp narrowly phylliform, pointed, reticulate, slightly barbed, inserted on tubercles, h 2, h 3 setiform, erect, slightly roughened, other setae very broad, reticulate, slightly barbed, inserted on tubercles; in PN, DN, TN, c 1 setiform, slightly barbed, h 1 (and p 1 in PN) narrowly phylliform, pointed, slightly barbed, inserted on tubercles, p 2, p 3 setiform, erect, slightly roughened, other setae very broad, reticulate, slightly barbed, inserted on tubercles. Opisthonotal gland opening and all cupules distinct in transmitted light. Exuvial scalps with nine pairs of setae; nymphal scalps with median hole.

Note: Roman letters refer to normal setae; Greek letters refer to solenidia (except ɛ—famulus); juxtaposition of seta d with solenidion indicates coupling. Single quotation mark (’) designates setae on the anterior and double quotation (”) setae on the posterior side of a given leg segment; parentheses indicate addition of both members of a pseudosymmetrical pair. Setae and solenidia are listed for the instar in which they first appear and should be presumed present for the remainder of ontogeny.

Gnathosoma ( Figs 4E–G ). Subcapitulum size: LA: 56 × 37; PN: 64 × 45; DN: 75 × 56; TN: 105 × 75; length of setae a and h: LA and PN: 11; DN: 15; TN: 22; length of seta m: LA and PN: 4; DN: 7; TN: 9; length of adoral seta: LA and PN: 4; DN: 5; TN: 7; all setae setiform, slightly roughened. Palp length: LA: 30; PN: 45; DN: 52; TN: 71; length of postpalpal seta: LA: 2; PN: 4; DN: 7; TN: 11; second seta on femur added in PN. Chelicera length: LA: 56; PN: 64; DN: 75; TN: 105; length of cha: LA: 15; PN: 19; DN: 22; TN: 26; length of chb: LA: 11; PN: 13; DN: 15; TN: 19; all setae setiform, barbed.

Epimeral region ( Figs 5A–D ). Setal formulas for epimeres: larva: 3-1-2 (1c as typical scale covering Claparède’s organ); protonymph: 3-1-2-1; deutonymph: 3-1-2-2, tritonymph: 3-1-3-3. Length of setae: LA and PN: 1b, 3b: 9–11, others: 5–7; DN: 1b, 3b: 13–15, others: 9–11; TN: 1b, 3b: 19–22, others: 11–15; all setae setiform, thin, slightly roughened.

Anogenital region ( Figs 5A–D ). Ontogeny of genital (PN: 5–7; DN: 7–11; TN: 11–15), aggenital (DN: 11; TN: 15–19), anal (TN: 7–15), and adanal (DN: 11–15; TN: 15–19) setal formulas, proto- to tritonymphs: 1-3-5, 0- 1-1, 0-0-2, 0-3-3, respectively; all setae setiform, thin, slightly roughened. Adanal cupule distinct; anal cupule not observed.

Legs ( Figs 4H, I ). Claw of each leg dorsally slightly barbed. Formulas of leg setation and solenidia: LA 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]; PN: I (0-2-3-4-16) [1-1-2], II (0-2-3-3-13) [1- 1-1], III (0-2-2-2-13) [1-1-0]; IV (0–0–0–0–7) [0–0–0]; DN: I (0–4–3–4–16) [1–2–2], II (0–4–3–3–13) [1–1–2], III (1–3–2–2–13) [1–1–0], IV (0–2–1–2–12) [0–1–0]; TN: I (1–4–4–5–18) [1–2–2], II (1–4–4–4–15) [1–1–2], III (2–3–2–4–15) [1–1–0], IV (1–2–2–4–12) [0–1–0]; homologies of setae and solenidia indicated in Table 1 .

Type material. Holotype (female) and nine adult paratypes (all females): USA, New York, St. Lawrence Co., E side of Silver Lake, just N of US, Rt. 3, Cranberry , Lake village , 44º13.6'N, 74º49.3'W, 470 m elev., moss, lichens from bark on rotting logs and stumps in northern hardwood, hemlock forest, 9.VIII.2013 (leg. R. A. Norton).

Two adult paratypes and nine juvenile instars (one larva, three protonymphs, two deutonymphs, three tritonymphs): USA, New York, St. Lawrence Co. nr. Oswegatchie River , without habitat data, 14.VII.1973 (leg. T. Finger) .

The holotype is deposited in the collection of the Senckenberg Museum of Natural History, Görlitz, Germany; 11 paratypes and all juvenile instars are 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.

Etymology. This species is named in honor of Dr. Roy A. Norton, Professor emeritus of the State University of New York, Syracuse, NY, USA, who collected and pre-identified all instars of the new species and kindly sent them to me for description.

Differential diagnosis. Adults of Eupterotegaeus nortoni sp. nov. is morphologically most similar to E. ornatissimus ( Berlese, 1908) and E. steinboecki ( Mihelčič, 1958) in the presence of a tooth in the rostral region and the well separated lamellar cusps. However, the new species differ from both in the presence (versus absence) of notogastral setae c and interbothridial tubercles, and in the absence (versus presence) of distal toothlike process on the lamellar cusps; also, E. ornatissimus has no interlamellar tooth (versus tooth present in the new species), and E. steinboecki is distinctly larger (length: 1030 versus 615–630) and has a small (versus medium-sized in the new species) rostral tooth.

Figures

FIGURE 1. Eupterotegaeus nortoni sp. nov., adult (gnathosoma and legs not shown): A—dorsal view; B—ventral view; C— right lateral view; D—posterior view. Scale bar 100 μm.

FIGURE 2. Eupterotegaeus nortoni sp. nov., adult:A—bothridial setae; B—subcapitulum, ventral view; C—palp, left, paraxial view; D—chelicera, right, antiaxial view; E—leg I, right, antiaxial view; F—leg II, right, antiaxial view; G—leg III, left, antiaxial view; H—leg IV, left, antiaxial view. Scale bar 20 μm (A–D), 50 μm (E–H).

FIGURE 3. Eupterotegaeus nortoni sp. nov., adult, SEM micrographs: A, C—dorsal view (cerotegument removed); B—distal parts of cusps of lamellae; D—dorsal view (outer layer of cerotegument removed); E—ventral view (cerotegument removed); F—right lateral view (cerotegument removed); G—surface and some seta in posterior part of notogaster.

FIGURE 4. Eupterotegaeus nortoni sp. nov., juvenile instars: A—larva, dorsal view; B—protonymph, dorsal view; C— tritonymph, dorsal view; D—tritonymph, medial notogastral tubercle, lateral view; E—tritonymph, subcapitulum, ventral view; F—palp, left, paraxial view; G—tritonymph, chelicera, left, paraxial view; H—tritonymph, leg I, right, antiaxial view; I—leg IV, left, antiaxial view. Scale bars 20 μm (E–G), 50 μm (A, D, H, I), 100 μm (B, C).

FIGURE 5. Eupterotegaeus nortoni sp. nov., juvenile instars: A—larva, ventral view; B—protonymph, ventral view; C— deutonymph, ventral view; D—tritonymph, ventral view; E—larval scalp; F—protonymphal scalp. Scale bars 50 μm (A, E), 100 μm (B, C–D, F).

FIGURE 6. Eupterotegaeus nortoni sp. nov., juvenile instars, SEM micrographs: A, B—tritonymph, dorsal view; C—some setae in posterior parts of proto- and deutonymphal exuvial scalps in tritonymph; D—protonymph, dorsal view.