Eurostocepheus (Eurostocepheus) sinutus, Zheng & Chen, 2021

Zheng, Lihao & Chen, Jun, 2021, Two new species and new records of Otocepheidae (Acari, Oribatida) from Yunnan, Southwest China, ZooKeys 1073, pp. 177-199 : 177

Eurostocepheus (Eurostocepheus) sinutus sp. nov.

Figures 6 , 7 , 8

Diagnosis.

Body size: 1500 × 850. Body ratio (length/width): 1.8. Body surface relatively smooth. Costula strong, a little “S” shaped curved, largest width of mutual distance anteriorly, curved inward around setae le. Pedotecta II disproportionately dilated, with smaller anterior parts and larger posterior parts projecting lateroposteriad. Eight pairs of notogastral setae, c, la, lm, lp setiform and slightly barbed distally, p 1, p 2, p 3, h 3 short and ciliform. Epimeral setal formula 3-1-3-3. A pair of ventral grooves between genital aperture and ventral ridge present.

Description.

Measurements (holotype, female). Body length: 1500, body width: 850. Setae length and mutual distance: ro 230, le 230, bs 150, ex 20; c, la, lm, lp range 210-250; p 1, p 2, p 3, h 3 range 40-60; c - c 370, la - la 430, lm - lm 470, lp - lp 470.

Integument. Body color dark brownish. Body surface relatively smooth.

Prodorsum. Rostrum broadly rounded. Rostral setae curved inward, densely barbed outside. Lamellar setae inserted behind tip of costula, curved inward, roughened externally. Interlamellar setae slightly barbed. Bothridial setae with a long fusiform head and a curved peduncle in dorsal view. Exobothridial setae short, hardly visible in dorsal view. Costula strong, weakly “S” shaped, largest width of mutual distance anteriorly, curved inward around setae le. Bothridium opening laterally, dorsal bothridial plate nearly straight, ventral bothridial plate invisible in dorsal view. Tutorium developed weakly. Lamelliform expansion curved and pointing to base of seta ro in lateral view. Two pairs of prodorsal condyles present, lateral prodorsal condyles broadly flattened and wide, median prodorsal condyles drop-shaped. Notogaster. L/W of notogaster about 1.1. Surface of notogaster relatively smooth in dorsal view, without visible foveola or granules. Anterior margin of notogaster distinctly moved forward. Lateral notogastral condyles trapezoid, with triangular tip outside, which markedly anterior to medial prodorsal condyles. Median notogastral condyles absent. Eight pairs of notogastral setae, c, la, lm, lp longer than others distinctly, setiform and slightly barbed distally, p 1, p 2, p 3, h 3 short and ciliform. All lyrifissures well visible, ip located between p 1 and p 2 on left side while it between p 2 and p 3 on right side, ips between h 3 and p 3. Opisthonotal gland openings located close to lyrifissure im. Vitta marginalis distinct. Lyrifissures im and setae lm almost located at same level.

Epimeral and lateral podosomal regions. Pedotecta II disproportionately dilated, with smaller anterior parts and larger posterior parts projecting lateroposteriad. Epimeral border I well visible. Apodemes I, II and sejugal apodeme well developed, epimeral foramen present. Sternal apodeme well developed. Epimeral setal formula 3-1-3-3. Epimeral setae slightly barbed, seta 4a inserted between 4b and 4c, and closer to 4c. Postpodosomal ornamentation present.

Anogenital region. Genital plates relatively smooth. Four pairs of genital setae (mutual distances g 1- g 1≈ g 2- g 2≈ g 4- g 4<g 3- g 3, g 2 longer than the rest). Aggenital lyrifissures located close and anterolateral to genital aperture. A pair of ventral groove present between genital aperture and ventral ridge. One pair of aggenital, two pairs of anal (mutual distances an 1- an 1<an 2- an 2) and three pairs of adanal setae short, similar in length. Setae ad 3- ad 3 below level of anterior margin of anal opening. Adanal lyrifissures located in diagonal position and close to anal aperture, below level of anterior margin of anal opening.

Gnathosoma. Subcapitular setae barbed. Rutellum pantelobasic, with typical dentation and rutellar brush. Chelicera chelate-dentate; with a minute denticle proximal to seta cha; cha longer than chb; Trägårdh’s organ narrowly triangular. Palp with usual setal formula: 0-2-1-3-8 (+ ω); setae of trochanter to tibia barbed. Tarsus with four short, blunt distal eupathidia- acm, su, (ul); base of solenidion ω constrainted by surface of tarsus, and thus adjacent to setae ul ', ul " medioanteriorly. Postpalpal setae erect, smooth.

Legs. Monodactylous. Claw of each leg strong and smooth. Formulae of leg setation and solenidia (Table 3 ): I (1-4-3-4-16) [1-2-2], II (1-4-3-3-15) [1-1-2], III (1-2-1-2-15) [1-1-0], IV (1-2-2-2-12) [0-1-0]. Leg setae u setiform (L-type) on tarsi I, thorn-like (S-type) on tarsi II-IV.

Material examined.

Holotype: female (in alcohol, ZLH-12-276): China, Yunnan Province, Yingjiang County, Taiping Town, Huilonghe Reservoir , 24°40'20"N, 97°45'28"E, 1769 m a. s. l., litter and soil under moss, 24 October 2012, collected by Lihao Zheng.

Type deposition.

Type specimen is deposited in the collection of the IZAS.

Etymology.

The specific name " Eurostocepheus sinutus " is from Latin for “sinus” refers to the ventral groove between genital aperture and ventral ridge.

Remarks.

As possessing the conspicuously developed costula and the distinctly dilated posterior pedotecta II, which are diagnostic characters of the genus, this new species should be placed into the genus Eurostocepheus . The new species can be easily distinguished from other known species of this genus by its huge body size, eight pairs of notogastral setae and its ventral groove between the genital aperture and the ventral ridge.

Figures

Figure 6. Eurostocepheus (Eurostocepheus) sinutus sp. nov., adult: a dorsal aspect (legs removed) b bothridial seta c epimeron IV (left, part), showing ventral groove (arrow) d ventral aspect (legs and mouthparts removed). Abbreviations and notations explained in text. Scale bars: 200 µm (a, d); 100 µm (b).

Figure 7. Eurostocepheus (Eurostocepheus) sinutus sp. nov., adult, microscope images: a dorsal view b ventral view c lateral view. Abbreviations and notations explained in text. Scale bars: 200 µm.

Figure 8. Eurostocepheus (Eurostocepheus) sinutus sp. nov., adult: a subcapitulum, ventral view b right palp, abaxial view c left chelicera, adaxial view. Abbreviations and notations explained in text. Scale bars: 50 μm.