Cheletomimus (Hemicheyletia) crinitus, Bochkov & Sidorchuk, 2016

Bochkov, Andre V. & Sidorchuk, Ekaterina A., 2016, A new Eocene free-living cheyletid mite from Baltic amber, Acta Palaeontologica Polonica 61 (4), pp. 869-874 : 871-873

Cheletomimus (Hemicheyletia) crinitus sp. nov.

Figs. 1–3 .

Etymology: From Latin crinitus , fluffy; in reference to numerous bush-like median setae on the dorsal shields of the idiosoma; masculine gender.

Holotype: Female, SMF Be 2537 (originally CCHH # 448-1 ).

Type locality: Baltic Sea coast, most likely Sambian Peninsula.

Type horizon: Middle to upper Eocene in amber, 37–54.5 Mya ( Poinar 1992; Weitschat and Wichard 2010).

Diagnosis. — This new species belongs to the C. (H.) wellsi species group (16 species) of the subgenus Hemicheyletia Volgin, 1969 . In females of this group, dorso-median setae of the idiosoma are aberrant, strongly different from lateral setae, and the hysteronotal shield is entire. Among species of this group, female of C. (H.) crinitus sp. nov. morphologically similar to those of C. greenwoodi Fain, Bochkov, and Corpuz-Raros, 2002 known from England ( Fain et al. 2002). In these species, tibia I bears five setae (excluding solenidion), seta l′′Ti on the palp tibia is thickened serrate, the hysteronotal shield bears median bush-like setae and lateral fan-like setae, including h1 and h2, seta ft of tarsus I present. Female of the new species differs from those of C. greenwoodi by the following features. In C. crinitus sp. nov., setae d2 are situated on the hysteronotal shield (vs. off this shield in C. greenwoodi ), the propodonotal and hysteronotal shields each bear five pairs of median setae (vs. 3 and 1 pairs of median setae, respectively), setae h1 and h2 are subequal in width to the other lateral hysteronotal setae (vs. half the width of other hysteronotal setae).

Description. — Female (holotype, SMF Be 2537). Body 435 long and 225 wide at the level of setae c2.

Gnathosoma: 135 long from the rostral apex to posterior margin of subcapitulum from ventral side and 90 wide at the level of supracoxal setae (elc). Peritremes arch-like, with five or six pairs of segments. Protegmen densely ornamented with tubercles. Tegmen (rostral shield) strongly punctate. Comblike eupathidia acm and sul each with numerous teeth (>15). Palpal claw with four teeth. Setae of palp tibia: dTi smooth, thickened; l′′Ti thickened serrate, l′ Ti filiform. Setae of palp genu: dG fan-like, 18 long and maximum 7 wide; l′′G displaced on femur, lanceolate, 20 long. Palpal femur 30 long and maximum 28 wide, covered by tubercles in the anterior half. Setae of palp femur: dF fan-like, 24 long and maximum 16 wide; setae v′ F and v′′F filiform.

Idiosoma: 315 long. Lateral setae of the idiosoma fan-like, subequal in size, about 25 long and maximum 23 wide; median setae of the idiosoma aberrant, bush-like. Length of propodonotal shield 135 along midline and 175 wide at level of the posterior margin; bearing four pairs of lateral setae and five pairs of median setae. Setae c2 fan-like, 45 long. Hysteronotal shield well developed, length 125 along midline, 170 wide at the level of the anterior margin, and 65 wide at level of the posterior margin; bearing five pairs of lateral setae, including d2 and h1, and five pairs of median setae. Setae h1 situated posterior to the level of setal bases h2. Distance between propodonotal and hysteronotal shields 10. Setae h3 fan-like, 35 long, situated terminally off the hysteronotal shield. Setae ps1 fan-like, 12 long, other pseudoanal setae filiform.

Legs: Solenidion ω1 22 long, companion seta ft present, 12 long. Tibia I with five setae and solenidion φ (three fan-like setae, d, l′, l′′ and two smooth filiform setae, v′, v′′); tibia II with two lanceolate setae, two smooth filiform setae and solenidion φ; tibiae III and IV each with two fan-like setae, one lanceolate seta, and one smooth filiform seta. Genua I–IV with two fan-like setae each (genu I with solenidion σ). Femur I with one fan-like seta and one smooth filiform seta; femora II and III with one fan-like seta and one barbed seta each; femur IV with one fan-like seta. Coxal seta 3b strongly barbed. Legs I 220 long; legs IV 155 long.

Geographic and stratigraphic range.— Type locality and horizon only.

Figures

Fig. 1. Cheyletid mite Cheletomimus crinitus sp. nov., female holotype (SMF Be 2537, ex. CCHH 448-1) from Baltic amber (Baltic Sea coast, most likely Sambian Peninsula, middle to upper Eocene, 37–54.5 Mya), reconstruction (leg positions altered for clarity). Dorsal (B) and ventral (C) views, right palp A) and left tibia and tarsus I (D) in dorsal views, left tarsus I in ventral view (E). Abbreviations: 1a–c, 2c, 3a–c, 4a–c, coxal setae of coxae 1–4, respectively; c2, d2, e2, f2, h1–h3, dorsal setae, associated with body segments C, D, E, F, H, respectively; ′ and ′′ refer to position of seta in pseudosymmetrical pair on appendage: anterior or posterior, respectively.

Fig. 2. Cheyletid mite Cheletomimus crinitus sp. nov., female holotype (SMF Be 2537, ex. CCHH 448-1) from Baltic amber (Baltic Sea coast, most likely Sambian Peninsula, middle to upper Eocene, 37–54.5 Mya), brightfield layered micropanaramas, each combined from ca. 170 focal planes. Dorsal (A) and ventral (B) views. Abbreviations: 1a–c, 2c, 3a–c, 4a–c, coxal setae of coxae 1–4, respectively; ag1, anterior aggenital seta; c2, d2, e2, f2, h1–h3, dorsal setae, associated with body segments C, D, E, F, H, respectively; oc, ocellus; se, scapular external prodorsal seta; si, scapular internal prodorsal seta; ve, vertical external prodorsal seta; vi, vertical internal prodorsal seta.

Fig. 3. Cheyletid mite Cheletomimus crinitus sp. nov., female holotype (SMF Be 2537, ex. CCHH 448-1) from Baltic amber (Baltic Sea coast, most likely Sambian Peninsula, middle to upper Eocene, 37–54.5 Mya). A. Dorsal view of gnathosoma and anterior opisthosoma (micropanorama assembled from ca 80 images). B. Detail of left palp in ventral view (assembled from 18 images). C. Posterior of ano-genital area in lateral antiaxial view in lateral antiaxial view (assembled from ca. 40 images). D. Left leg I tarsus in lateral antiaxial view (from 22 focal planes). Note extremely poor visibility of seta p′′ against the background of the leg. Abbreviations: a, antelateral seta; acm, anteroculminal palpal eupathidia; ag1–3, aggenital setae, b.s., bush-like seta; d, dorsal seta; elc, supracoxal seta; emp, empodium; F, femur; ft, fastigial seta; G, genu; g1–2, genital setae; h3, seta of segment H; l, lateral seta; oc, ocellus; p , proral seta; per, peritreme; ps1–3, pseudanal setae; tc, tectal seta; Ti, tibia; ti.cl, tibial claw; u, unguinal seta; ul, ultimal palpal eupathidium; ve, vertical external prodorsal s4eta; vi, vertical internal prodorsal seta; vs, ventrosagittal seta; ω, tarsal solenidion; ′ and ′′ refer to position of seta in pseudosymmetrical pair on appendage: anterior or posterior, respectively.