Body in life usually greenish or white, females of some species show black coloration after being placed in ethanol or potash. Body of adult female on slide oval to elongate oval. Antennae seven- or eight- segmented. Circulus present or absent. Legs well developed, claw without a denticle. Both pairs of ostioles well developed. Anal ring usually situated at apex of abdomen, bearing six setae. Anal lobes moderately developed, each bearing a normal apical seta. Cerarii numbering 1–17 pairs, each cerarius usually bearing two conical setae. Trilocular pores numerous, evenly scattered on all body surface. Multilocular disc pores usually present on venter, more rarely present on dorsum. Oral rim ducts present, forming transverse rows on dorsum and sometimes present on venter. Oral collar tubular ducts present, at least on venter, sometimes present on dorsum. Most species have group of oral collar tubular ducts on prothorax in front of anterior spiracles, often accompanied by a group of multilocular disc pores. Flagellate setae of different sizes present on both body surfaces (adapted from Tang 1992, Danzig and Gavrilov-Zimin 2015).

Holotype. ♀ (mounted singly on a slide), China, Jiangxi Province, Fuzhou City, Rushui Forest Park [27°58'N, 116°22'E], under the leaf sheath of Sporobolus fertilis (Poaceae), 2.x.2019, coll. Jiang-Tao Zhang. Paratypes. 8 ♀♀ (mounted on 8 slides), same data as holotype.

The species name is based on the collection locality, Rushui Forest Park.

Alive: body elongate, dark reddish, with thin covering of white mealy wax, and only caudal filaments present (Fig. 1).

Figure 1. 

Habitus photograph of Atrococcus rushuiensis sp. nov. under the leaf sheath of Sporobolus fertilis (Poaceae).

Slide-mounted specimens (N = 6): body of adult female (Fig. 2) elongate, 2.5–3.1 mm long, 0.9–1.4 mm wide. Anal lobes moderately developed, ventral surface of each lobe bearing an apical seta, each 100–122.5 μm long. Antennae eight-segmented, 267.5–289 μm long, lengths of each segment: I 42.5–52.5, II 37.5–38.8, III 23.8–27.5, IV 18.8–22.5, V 17.5–23.8, VI 20–26.3, VII 28.8–32.5 and VIII 65–76.3 μm. Eye spot located at body margin lateral to antennal base. Legs well developed; hind coxa 52.5–65 μm long, hind trochanter + femur 185–215 μm long, hind tibia + tarsus 198.8–240 μm long; claw 17.5–22.5 μm long, both tarsal digitules and claw digitules knobbed, longer than claw. Ratio of lengths of hind tibia + tarsus to hind trochanter + femur 1.07–1.14:1. Ratio of lengths of hind tibia to tarsus 1.49–1.69:1. Translucent pores present, minute duct-like, present on anterior and posterior surface of hind coxa. Circulus absent. Clypeolabral shield 125–145 μm long. Labium with three segments, 62.5–70 μm long. Ostioles moderately developed, each lip with 4–13 trilocular pores and 0–2 short setae. Anal ring normal, 61.3–70 μm in diameter, bearing six long setae, each seta 82.5–103.8 μm long. Cerarii numbering a single pair on anal lobes only. Anal lobe cerarii (C₁₈) each containing two slender conical setae, each seta 18–21 μm long, with 2–3 auxiliary setae, and 4–5 trilocular pores near conical setae base, all situated on a membranous area.

Figure 2. 

Adult female of Atrococcus rushuiensis sp. nov. Venter (A–I) A flagellate seta B large type of oral collar tubular duct C disc pore D trilocular pore E oral rim duct F hind coxa G claw H small type of oral collar tubular duct I multilocular disc pore. Dorsum (J–P) J anal lobe cerarius K anal ring L multilocular disc pore M oral rim duct N trilocular pore O disc pore P dorsal seta.

Dorsum. Setae short and slender, each 15–25 μm long. Trilocular pores each 3.5 μm in diameter, evenly distributed. Oral rim ducts each 9–10 μm long, 6 μm wide, in more or less single transverse rows on most segments. Oral collar tubular ducts absent or present, if present, each 6–7 μm long, 3 μm wide, having fewer numbers marginally on abdominal segments VI or VII. Multilocular disc pores each 7–8 μm in diameter, forming transverse rows or scattered on medial abdominal segments V–VII (V has 0–7 pores, VI has 1–7 pores, VII has 3–12 pores), occasionally few present on margin of abdominal segments V–VII. Discoidal pores minute, scattered.

Venter. Setae slender, longer than those on dorsum, each 36.3–80 μm long. Trilocular pores similar to those on dorsum, evenly distributed. Oral rim ducts same as those on dorsum, present on margin and submargin areas of thoracic and abdominal segments. Oral collar tubular ducts of two types: a large type, similar to those on dorsum, present in transverse rows across abdominal segments III–VIII or IV–VIII, also in marginal groups on abdominal segments V–VIII or VI–VIII, and a small group (together with multilocular disc pores) present on prothorax in front of anterior spiracles (4–11 ducts and 6–17 pores); a small type, each 5 μm long, 2 μm wide, mainly distributed across middle areas of abdominal segments III–VIII or IV–VIII, a few also present on margin with large ducts. Multilocular disc pores same as those on dorsum, numerous, present posterior to vulva, in transverse rows at posterior edges of abdominal segments IV–VII, in transverse rows at anterior edges of abdominal segments VI–VII, a few occurring on submargin areas of abdominal segments II–IV near oral rim ducts, also forming groups along margin of abdominal segments V–VIII or VI–VIII. Discoidal pores minute, scattered.

Poaceae: Sporobolus fertilis.

China: Jiangxi (Fuzhou).

Living under the leaf sheath of its host plant.

Atrococcus rushuiensis sp. nov. is very similar to A. luffi (Newstead) in the number of cerarii and multilocular disc pores present on both body sides, but it differs from the latter by the following features (condition of A. luffi given in parenthesis): (i) dorsal margin oral collar tubular ducts absent or few (numerous, with multilocular disc pores in submarginal groups up to segment III); (ii) ventral oral rim ducts absent in median areas of prothorax and mesothorax (present in these areas); (iii) translucent pores duct-like (normal, not duct-like) [The morphology of A. luffi is mainly based on Williams (1962)].

The new species also resembles A. paludinus in possessing fewer than 20 oral rim ducts on each segment, which is different from A. luffi in having about 20 oral rim ducts on each segment, but differs from the latter by the following features (condition of A. paludinus given in parentheses): (i) cerarii numbering one pair only (cerarii numbering 6–7 pairs); (ii) Translucent pores duct-like (normal, not duct-like) [The morphology of A. paludinus is also mainly based on Williams (1962)].

In A. rushuiensis sp. nov., the number of ducts and pores vary among individuals, which belong to intraspecific variation. Some specimens have only a small number of ducts and pores, but in other specimens those ducts and pores are much more numerous.