Cryptotendipes casuarius (Townes)

Saether, Ole A., 2010, Cryptotendipes Lenz from Manitoba, Canada, with keys to known immatures of the genus (Diptera: Chironomidae), Zootaxa 2412, pp. 1-20 : 10-12

Cryptotendipes casuarius (Townes)

Harnischia casuria Townes, 1945: 162 . ( Fig. 5 )

Material examined. USA: South Dakota, Lake Francis Case, 5 miles north of Pickstown, 2 males reared from pupae, no date, P.L. Hudson. CANADA: Manitoba, South Indian Lake, Long Bay, female reared from larva, 15.vi. 1976, E. Phillips. Lake Winnipeg records: Victoria Beach, 736 males, 9. & 25.vii. 1969; Pine Dock, 279 males, 10.vii. –2.ix. 1969; 0.5 km off George Island, 2 males, 12.vii. 1969; 3 km off Grand Rapids, 4 males, 13.vii. & 4.ix. 1969; 10 km off Sturgeonskin (Long) Point, 4 males, 14.vii. 1969; Gull Harbour, 319 males, 16.vii. 1969; Gimli Government Warf, 24 males, 24.vii. 1969; Matheson Island Government Warf, 8 males, 26.vii. 1969; 3 km off George Island, 38 males, 27.vii. 1969; Grand Rapids Government Warf, 37 males, 28.vii. 1969; 5 km of Selkirk (Horse) Island, 182 males, 29.vii. 1969; East of Selkirk Island, 1 male, 29.vii. 1969; North-northeast off Reindeer Island, 1 male, 30.vii. 1969; McBeth Harbour, 48 males, 7.ix. 1969; Hnausa Government Wharf, 1 male, 8.ix. 1969; Hecla Island, 312 males, 3.vi. –13.ix. 1971; Beaver Point, 42 males, 18.vi. –8.viii. 1971; 20 Mile Creek, 1 male, 1.ix. 1971; Old Fishing Dock, 301 males, 29.vi. – 27.viii. 1971; Calder’s Dock, 168 males, 6.vii. –31.viii. 1971; South Basin, 13 pupae, 241 larvae, 9.vii. –31.x. 1969; Narrows, 12 larvae, 4.vi. –31.x. 1969; North Basin, 62 pupae, 473 larvae, 4.vi. –31.x. 1969.

The male imagines have 3–11, 7 (10) setae on squama; 3–6, 5 (10) sensilla chaetica on p2, none on p3. The hypopygium is illustrated by Saether (1977a fig. 34 B–D). The female genitalia are illustrated by Saether (1977b, fig. 85 A–C). A female from South Indian Lake, Man., has 11 sensilla chaetica on each ta l of p2 and p3.

Pupa (n = 5–6, except when otherwise stated)

Total length 4.49-5.16, 4.86 mm. Exuviae nearly transparent with pale yellowish grey thorax.

Cephalothorax. Thoracic horn 3.74–4.73 mm (3) long, main stem 2.03–2.47 mm (3) long. Cephalic tubercle 26–40 µm (2) high, 22–30 µm (2) wide, with 26–36 µm (2) long frontal seta.

Abdomen ( Figs 5 A, B). Shagreen and chaetotaxy as illustrated. Caudal margin of T II with 16–27, 21 hooklets. Numbers of caudal spines on T II–VII: 16–27, 21; 6–26, 15; 28–42, 37; 27–37, 34; 38–41, 40; 50– 85, 68. Lengths of caudal spines on T II–VII (in µm): 8–12, 10; 6–10, 8; 16 16–20, 18; 11–20, 17; 16–24, 19; 20–26, 22. S I with groups of 13–23 µm (3) long spinules. Numbers of caudal spines on S II–IV: 0–5, 3; 0–9, 5; 0–8, 2. Lengths of caudal spines on S II–IV (in µm): 0–10, 4; 0–12, 6; 0–4, 1. VIII with 146–180, 161 µm long spur; 16–28, 21µm wide at base; located 50–-110, 90 µm from caudolateral corner. Segments V–VIII each with 4 taeniate L-setae. Genital sac of male with 20–24 µm (2) long apical point, overreaching anal lobe by 108–110 µm (2); genital sac of female with 50-60 µm (3) long apical point, overreaching anal lobe by 0–?201, (2). Anal lobe with 26–29, 27 taeniae becoming gradually wider (to 12 µm) and slightly darker towards apex.

Fourth instar larva (n = 10, except when otherwise stated)

Total length 2.76–8.10, 5.86 mm (160). Head capsule length 0.26–-0.36, 0.31 (618). Head capsule brownish yellow with about 70–110, 85 µm long, 130–190, 150µm wide brownish black ventral spot.

Head. Antenna as in Fig. 5 C. Lengths of antennal segments (in µm): 49–53, 52; 10–14, 13; 4–7, 5; 3–5, 4; 4–6, 5. AR 1.70–2.17, 1.91. Basal antennal segment 16–21, 18µm wide; ring organ 16–23, 19 µm from base; blade 16–26, 21 µm; accessory blade 14–20, 16 µm long. Apical style of second segment 6–9, 7 µm long. Labrum ( Fig. 5 D) with S I 16–22, 19 µm long; S II 30–41, 33 µm long. Premandible ( Fig. 5 D) 66–88, 73µm long. Mandible 105–136, 125 µm long. Median tooth of mentum ( Fig. 5 E) 13–15, 14 µm wide; three median teeth combined 30–38, 32 µm wide; mentum when flattened 94–124, 112 µm wide. Ventromental plate 84– 110, 92 µm wide; 31–50, 38 µm long. Postmentum 159–180, 171 µm long.

Abdomen. Procercus 16–30, 24 µm high; 20–28, 26 µm wide; with 510–613, 594 µm long anal setae. Supraanal seta 280–405, 331µm; supraanal seta/anal setae 0.51–0.66, 0.56. Anal tubules triangular, 84–102, 91 µm long; 38–56, 46 µm wide at base. Posterior parapods 160–205, 201µm long.

Third instar larva

Total length 2.41–3.70, 3.30 mm (11) long. Head capsule length 0.17–0.21, 0.19 mm (93) long.

Second instar larva

Head capsule length 0.12–0.13, 0.12 mm (3). For distribution of head capsule length between instars see also Fig. 8 .

Distribution and ecology. The species is known from lakes, streams, rivers and ditches in Alberta, Manitoba, Ontario, New York, Kansas, Kentucky, North Carolina and south to Florida ( Townes 1945: 162, Beck and Beck 1969: 296, Oliver et al. 1990: 44, Epler 2009).

Figures

FIGURE 5. Cryptotendipes casuarius (Townes), immatures. A – pupal tergites; B – pupal sternites; C – larval antenna; D – labrum and epipharynx; E – mentum.

FIGURE 8. Head capsule lengths of different instars of Cryptotendipes darbyi (Sublette) and Cryptotendipes casuarius (Townes) in Lake Winnipeg.