Cryptochironomus curryi Mason

Saether, Ole A., 2009, Cryptochironomus Kieffer from Lake Winnipeg, Canada, with a review of Nearctic species (Diptera: Chironomidae), Zootaxa 2208, pp. 1-24 : 19-21

Cryptochironomus curryi Mason

( Fig. 6 A, B; 8)

Cryptochironomus curryi Mason 1986: 404 .

Cryptochironomus fulvus Curry 1958: 435 , Darby 1962:162, nec Johannsen 1905: 224.

Material examined. CANADA: Manitoba, Heming Lake, female reared from larva, 2.viii. 1967, A.P. Wiens. Lake Winnipeg record: Beaver Creek, 1 male, 19.viii. 1971.

The previously undescribed female is characterized by a wing length of about 2.4 mm, LR l of about 1.7, and absence of frontal tubercles.

Male imago

The hypopygium is illustrated by Darby (1962, fig. 49) and Mason (1986 fig. 2).

Female imago (n = 1)

Total length 4.93 mm. Wing length 2.42 mm. Total length/Wing length 2.03. Wing length/length of profemur 2.40.

Head. AR 0.48. Temporals 21. Clypeus with 22 setae. Frontal tubercles absent. Palp lengths (microns): 37, 73, 267, 143, 240.

Thorax. Antepronotum with 9 setae. Dorsocentrals 33, acrostichals 21, prealars 6. Scutellum with 29 setae.

Wing. VR 1.11. Brachiolum with 2 setae, R with 27, R1 with 23, R4+5 with 55 setae. Squama with 24 setae.

Legs. Sensilla chaeticae 25 on mid leg, 11 on hind leg. Lengths and proportions of legs as in Table 4.

fe ti ta1 ta2 ta3 ta4 ta5 LR BV SV BR p1 1009 714 1227 558 469 394 170 1.72 1.85 1.40 2.20 p2 874 832 503 252 190 120 83 0.60 3.42 3.39 2.64 p3 925 1126 748 340 286 167 110 0.66 3.10 2.74 4.58 Genitalia ( Fig. 8 A). Cercus 113 µm long. Gonocoxite IX bare. T IX with 58 setae. Segment X with 4 setae on each side. Notum 210 µm long. Seminal capsules 110 µm long, 67 µm wide.

Pupa (n = 1)

Total length 6.5 mm (7.0 mm in Curry 1958:435, table 4).

Cephalothorax. Cephalic tubercles ( Fig. 6 B) fused at base, 418 µm long (500 µm in Curry, 590–648 µm in Mason), 350 µm wide at base; main branch 124 µm long, 68 µm wide below lateral branch, 25 µm wide below frontal seta; lateral branch 95 µm long; frontal seta 70 µm long.

Abdomen ( Fig. 6 A). Tergites and sternites not reticulated. Shagreen and chaetotaxy as illustrated. Caudal margin of T II with 38–41 hooklets to each side of 90 µm (Curry) – 200 µm wide mesal interruption. Pedes spurii A present on S IV–VI, longest spinules 23 µm on IV, 6–7 µm on V–VI. Caudal margins of T III–VII (VIII in male according to Curry) respectively with the following numbers of spines (lengths in parentheses): 41(9 µm), 49 (9 µm), 48 (12 µm), 37 (16 µm), 32 (14 µm). Caudal margins of S II with 24, up to 7 µm long spines; of S III with 10, up to 4 µm long; of VII with 20, up to 14 µm long spines; other sternites without caudal spines. Caudomedian projection of anal lobe 240 µm long, 240 µm wide at base; with 56 µm long, 18 µm wide branches. Genital sac with 30 µm long, 30 µm wide apical point. Fringe of anal lobe with 73 filaments (64–82 in Mason).

Fourth instar larva (n = 1)

Head capsule length 0.49 mm.

Head. Antenna as in Fig. 8 B. Lengths of antennal segments (in µm): 72, 36, 30, 4, 4. AR 0.97 (0.95–1.15 in Mason, 0.95 in Curry 1958: 435, table 3). Basal antennal segment 27 µm wide, 2.00 times as long as second segment, ring organ 40 µm from base. Preapical blade of second segment 46 µm long, apical style 9 µm long. Labrum ( Fig. 8 C) with 33 µm long labral sensilla, S I 30 µm, S II 58 µm long. Premandible 106 µm long (110 in Curry). Mandible ( Fig. 8 D) 148 µm long (144 in Mason, 140 µm in Curry), with 36 µm long apical tooth which is 0.24 times as long as mandible. Basal segment of maxillary palp 56 µm long, 21 µm wide. Median tooth of mentum ( Fig. 8 E), including darker lateral accessory teeth, 48 µm wide. Ventromental plates 156 µm wide, 42 µm long, 3.71 times as wide as long (170 µm wide, 40 µm long in Curry). Postmentum 188 µm long. Abdomen. Procercus 34 µm wide, with 555 µm long anal setae.

Distribution and ecology. Curry (1958, table 2) mentions the species (as C. fulvus ) from the silty littoral and sublittoral of a lake and from a pond in Michigan. Darby (1962:162) found the species (as Tendipes fulvus ) in rice fields in California where most of the larvae occurred in deep standing or slowly flowing water. Mason (1983: 406) collected the species from sandy substrates in Saskatchewan River and Tobin Lake. Thus the only certain records for C. curryi are Saskatchewan, Manitoba, Michigan, and California. However, the males almost certainly are included in previous records of C. fulvus .

Figures

FIGURE 6. Cryptochironomus spp., pupae. A - tergites of C. curryi Mason; B – D cephalic tubercles of (B) C. curryi, (C) C. fulvus (Johannsen), (D) C. ponderosus (Sublette), (E) C. eminentia Mason.

FIGURE 8. Cryptochironomus curryi Mason, female and larva; A— female genitalia; B — antenna; C — labrum and epipharynx; D — mandible; E — mentum.