Cryptotendipes pseudotener Goetghebuer

Cryptotendipes pseudotener (Goetghebuer)

(Fig. 7)

Cryptochironomus pseudotener Goetghebuer, 1922: 38.

Material examined. USA: Nebraska, Missouri River, 1 mile north of Niobrara, mature male pupa, 18.vii. 1965, P.L. Hudson; South Dakota, Yankton, Missouri River, male reared from pupa, 22.vi. 1972, P.L. Hudson; South Dakota, Missouri River, 2 miles east, 6 miles south of Gayville, male and female reared from larvae, male, 29.v. 1972, P.L. Hudson; South Dakota, Springfield, Missouri River, 2 males reared from larvae, 18.vii 1972, P. L. Hudson; South Dakota, Yankton, Missouri River, tailwaters, Gavins Pt. Dam, male reared from larva, pupa reared from larva, 25–29.v. 1972, P.L. Hudson; South Dakota, Yankton, 6 males, Yankton, S.D., Lewis and Clark Lake, Gavins Pt. Dam, smartweeds, and north shore, 21.v–9.ix. 1969, P.L. Hudson; South Dakota, Lake Francis Case, 5 miles north of Pickstown, male, no date, P.L. Hudson. CANADA: Manitoba, Pinawa, Winnipeg River, 4.v. 1967, J. Ireland.

L. Winnipeg record: Centre of South Basin, male reared from pupa, 31.x. 1969.

Only one larva was present in the bottom samples and no imagines were taken in light traps. The species is, however, present in Winnipeg River, one of the main tributaries to the lake. The male imagines have 4–6, 5(10) sensilla chaetica on p2; 0–2, 1 on p3. The hypopygium is illustrated by Saether (1977a, fig. 34 F). A female imago has 9 sensilla chaetica on p2, 6 on p3. Its genitalia are illustrated in Saether (1977b, fig. 85 F–G).

Pupa (n = 9–10, except when otherwise stated)

Total length 3.07–4.14, 3.80 mm. Exuviae almost transparent with thorax pale grayish yellow.

Cephalothorax. Thoracic horn 2.68–3.48, 3.17 mm (7) long; main stem 1.77–2.72, 2.18 mm long. Cephalic tubercle (Fig. 7 C) 39–66, 52 µm high; 22––50, 36 µm wide; with 32–54, 46 µm long frontal seta.

Abdomen (Fig. 7 A, B). Shagreen and chaetotaxy as illustrated. Caudal margin of T II with 25–37, 31 hooklets. Number of caudal spines on T II–VI: 15––40, 28; 19–37, 27; 19–25, 21; 28–37, 33; 35–54, 44. Lengths of caudal spines on T II–IV 6–18, 13 µm; on T V and VI 16–32, 23µm. S I with four groups of 11–31, 20 µm long spinules. S II and VI each with 0–18, 7 caudal spines; 0–14, 8 µm long. S III–V each with 8–29, 17 caudal spines, 8–19, 15 µm long. VIII with 81–136, 97 µm long spur; 12–26, 18 µm wide at base; located 40–80, 57µm from caudolateral corner. Segments V–VIII each with 4 taeniate L-setae. Genital sac with 26– 36, 32 µm long apical point; male sac overreaches anal lobe by 86–135, 107 µm; female sac by 40 µm (1). Anal lobe with 31–37, 35 taeniae of equal width.

Fourth instar larva (n = 3, except when otherwise stated)

Total length 4.43 mm (1). Head capsule length 0.21–- 0.23 mm. Head capsule brownish yellow with about 59–64 µm long, 140–153 µm wide brown ventral spot.

Head. Antenna as in Fig. 7 D. Lengths of antennal segments (in µm): 31–34, 6––8, 4–5, 4–5, 3–4. AR 1.48–1.55. Basal antennal segment 11–13µm wide, ring organ 10 µm (1) from base, blade 15–16µm (2) long. Labrum with S I 22–26 µm long, S II 26–32 µm long. Premandible 52–53 µm (2) long. Mandible 90–94 µm (2) long. Median tooth of mentum 14–22, 18 µm (4) wide; three median teeth combined (or median tooth with lateral notches) 27–36, 32 µm (4) wide; mentum (Fig. 7 E) 70–95 µm wide. Ventromental plate 60–68 µm wide, 30–34 µm long. Postmentum 108–110 µm long.

Abdomen. At least some abdominal segments with branched, featherlike setae. Procercus 20–26 µm (2) high, 24–28 µm (2) wide, with 548–-550 µm (2) long anal setae. Supraanal seta 300–?20 µm (2), supraanal seta/anal setae 0.55–0.58 (2). Anal tubules triangular, 78–80 µm (2) long, 46–52 µm (2) wide at base. Posterior parapods 160 µm (1) long.

Distribution and ecology. The species was previously known from northern and western Europe, and from District of Columbia, New York, Pennsylvania, Michigan, Ohio and South Dakota (Townes 1945: 164, Oliver et al. 1990: 44, Saether & Spies 2004). I have also seen specimens from Lake Sakakawa, North Dakota.

According to Roback (1957:102) C. pseudotener is a very common species. It occurs in streams, rivers, reservoirs and lakes.