Chorizococcus altoarcticus Richards

CHORIZOCOCCUS ALTOARCTICUS (Richards) (Fig. 6) Pseudococcus (Trionymus) altoarcticus Richards, 1964: 1459. Chorizococcus altoarcticus (Richards): MacKenzie, 1967: 88; Ben­Dov, 1994: 83. This species has been recorded only from the Northwest Territories of Canada, on Ellesmere Island, collected in water traps and off Dryas integrifolia (Rosaceae). (Described mainly from 3 unstained paratype specimens, 1 in good condition, others slightly distorted.) Unmounted material: not known. Mounted material. Oval in outline, 1125–1500 µm long and 600–850 µm wide; anal lobes moderately developed; antennae 7 or 8 segmented; legs relatively short; circulus present; with only 3 pairs of cerarii; oral rim ducts present. Dorsum. Membranous, with frequent fine setae, each 10–20 µm long; setae absent medially on abdominal segment VIII. Trilocular pores relatively sparse and fairly evenly distributed. Simple (discoidal) pores scarce throughout, perhaps of two sizes; also with 1 or 2 small convex pores dorsad to each scape. Cerarii present on abdominal segments VI, VII and VIII, each with two stout spinose setae (stoutest on VIII), length of setae on VIII 18–21 µm; with 10 or 11 auxiliary setae, longest about 40 µm; setae in position of cerarius on segment V further apart and slightly stouter than normal setae but without associated trilocular pores. Ostioles membranous, each lip with few trilocular pores and no setae. Oral rim ducts each 6–7 µm wide, present as follows (totals across segment): VIII 0 or 1 on each anal lobe; VII 2–4; VI & V 2–5; IV–I 0–5; meta­ to prothorax 0–3; head 0 or 1. Oral collar ducts: only smaller ducts present, each about 4–5 µm long and 2.0µm wide on dorsum, with about 5–10 across middle of segments II–VI. Multilocular disc­pores absent. Anal ring 45–50 µm wide and about 55 µm long, with 6 setae, each about 70–86 µm long. Venter. Membranous, with frequent fine setae, each 11–30 µm long, some obviously longer than those on dorsum; suranal setae 28–40 µm long; long anal lobe setae each 90– 105 µm long. Trilocular pores relatively sparse and fairly evenly distributed. Simple (discoidal) pores as on dorsum. Oral rim ducts: with 0 or (generally) 1 on lateral margins of most segments. Oral collar ducts of 2 sizes: larger ducts located most abundantly near margin but also sparsely along posterior margin of segments III–VII; smaller ducts in a transverse line medially across each segment and near margins of all abdominal segments; also with a few on all thoracic segments. Multilocular disc­pores quite large, 6–7 µm wide, present on abdomen as follows (totals across segment): VIII 20–22 throughout segment; VII 14 or 15 along posterior margin and 7–12 along anterior margin; VI 15–19 post. + 7– 13 ant.; V 15–21 post. + 0–5 ant.; IV 8–13 post. + 0 ant.; III 1–3 post; II 0; absent more anteriorly. Circulus 33 µm long and 45–50 µm wide, with a transverse membrane medially. Eyespot about 25 µm wide. Antennae 7 or 8 segmented, 220–240 µm; segments II–VI each with usually 4 setae but preapical segment also with a fleshy seta; apical segment with 4 fleshy setae, 8 hair­like setae and about 5 stiff setae; apical seta about 16 µm long. Clypeolabral shield about 95 µm long; labrum about 85–90 µm long, with 11 pairs of setae. Spiracles: width of peritremes 16–20 µm. Metathoracic legs: lengths (µm): coxa 92–113; trochanter + femur 150–175; tibia 115–130; tarsus 70–77; claw 21–24; number of setae: coxa 7 or 8; trochanter 4 or 5 (longest 50–58 µm); femur 7; tibia 7 or 8 (tibia with two spurs, each 16–18 µm long); tarsus 8 or 9; translucent pores quite abundant on lateral half of each metacoxa, with a few occasionally on femur and usually some on distal dorsal margin of tibia. Both tarsal and claw digitules capitate; claw without a denticle. Vulva obvious, between segments VII and VIII. Material examined: PARATYPES Ψ: CANADA, Ellesmere Is., Lake Hazen, on Dryas integrifolia, 11.viii. 1962, R.B. Madge (CNC): 1 / 4 adΨΨ (2 good, 2 poor); as previous, 12.viii. 1962 (CNC): 3 / 2 adΨΨ (1 poor) + 1 imm. Comment. Richards (1964) considered this species to be closest to Trionymus thulensis. However, species in the genus Trionymus (as now defined) lack oral rim ducts and mostly have a small undivided circulus and so this species is easily separable. This description agrees quite closely with the fairly brief description given by Richards (1964) apart from the following (details from Richards in brackets): (i) only 2 spinose setae were noted in each cerarius (2 or 3); (ii) multilocular disc­pores present on abdominal segments VIII–III inclusive (VIII–V inclusive, although he illustrates them as also being present on segment IV); (iii) multilocular disc­pores absent from along anterior margins of abdominal segments V–III ("mainly arranged in an anterior and posterior row on each segment"), (iv) circulus divided across middle (circulus undivided), and (v) antennae 7 or 8 segmented rather than just 7 segmented. Richards did not mention the presence of translucent pores on the metafemur and metatibia.

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