Cryptochironomus digitatus (Malloch) Malloch
- Dataset
- Cryptochironomus Kieffer from Lake Winnipeg, Canada, with a review of Nearctic species (Diptera: Chironomidae)
- Rank
- SPECIES
Classification
- kingdom
- Animalia
- phylum
- Arthropoda
- class
- Insecta
- order
- Diptera
- family
- Chironomidae
- genus
- Cryptochironomus
- species
- Cryptochironomus digitatus
description
Abdomen. T I – V, anterior portion of T VI, S I – V and margins of S VI – VIII with reticulation. Caudal margin of T II with 31 – 43 hooklets on each side of 90 – 1601, wide interruption. Pedes spurii A present on S IV – VII, spinules 36 – 40 µm long on IV, 14 – 18 µm long on V – VII. Caudal margin of 25 T I – VII respectively with following numbers of spines (lengths in parentheses): 32 – 56 (20 – 34 µm), 50 – 52 (24 – 30 µm), 17 – 26 (48 – 50 µm), 15 – 29 (32 – 50 µm), 18 – 25 (50 µm), 21 (42 – 52 µm), 17 – 43 (30 – 36 µm). Caudal margins of S I – VII respectively with following numbers of spines (lengths in parentheses): 27 – 60 (35 – 38 µm), 12 – 17 (20 – 30 µm), 21 – 28 (40 – 50 µm), 15 – 26 (20 – 38 µm), 7 – 30 (24 – 28 µm), 0 – 38 (0 – 34 µm), 0 – 26 (0 – 18 µm). Caudomedian projection of anal lobe 282 – 442 µm long, 276 – 313 µm wide; with 88 – 130 µm, long, 22 µm wide branches. Genital sac of male with 54 – 74 µm long, 44 – 54 µm wide apical point. Fringe of anal lobe with 99 – 106 filaments. Fourth instar larva (n = 9 – 10, except when otherwise stated, tentatively associated) Total length 7.99 – 12.67, 10.04 mm. Head capsule length 0.66 – 0.77, 0.71 mm (23). Head. Antenna as in Fig. 3 D. Lengths of antenna] segments (in µm): 82 – 98, 90; 28 – 35, 32; 16 – 20, 19; 2 – 4, 2; 2 – 4, 4. AR 1.41 – 1.72, 1.56. Basal antennal segment 35 – 39, 37 µm wide; 2.45 – 3.29, 2.80 times as long as second segment; ring organ 50 – 70, 62 µm from base. Style of second segment 10 – 12, 11 µm long. Labrum (Fig. 3 E) with 35 – 40, 38 µm (8) long labral sensilla; S I 26 – 42, 33 µm (6); S II 50 – 60, 54 µm (4) long. Premandible 148 – 180, 160 µm long. Mandible (Fig. 3 F) 190 – 220, 210 µm long; with 43 – 55, 50 µm apical tooth which is 0.20 – 0.26, 0.24 times as long as mandible. Basal segment of maxillary palp 58 – 76, 70 µm long; 26 – 30, 28 µm wide. Median tooth of mentum (Fig. 3 G) including darker lateral accessory teeth 62 – 68, 65 µm wide. Ventromental plate 190 – 220, 201 µm wide; 50 – 60, 57 µm long; 3.28 – 3.80, 3.51 times as wide as long. Postmentum 250 – 308, 267 µm long. Abdomen. Procercus 42 – 52, 49 µm high; 39 – 46, 43 µm wide; with 552 – 761, 677 µm long anal setae. Supraanal seta 330 – 435, 400 µm (7); supraanal seta / anal setae 0.57 – 0.70, 0.61 (7). Anal tubules triangular 192 – 250, 222 µm (5) long; 100 – 130, 112 µm (5) wide at base. Posterior parapods 368 – 515, 436 µm long. Third instar larva Head capsule length 0.40 – 0.48, 0.44 mm (44) (See Fig.) Second instar larva Head capsule length 0.26 – 0.29, 0.28 mm (5) (See Fig.)
distribution
Distribution and ecology. The species was previously known from Yukon to New Foundland and south to California, New Mexico, Texas and Florida (Townes 1945: 100, Sublette and Sublette 1965: 167, Oliver et al. 1990: 44, Epler 2009). Mozley (1975: 102, 104) found the species in the sandy littoral (down to 8 m) in Lake Michigan. This and other observations indicate that C. digitatus has an ecology conforming to that of other numbers of the Harnischia - complex living in the sandy littoral of large lakes and rivers.
materials_examined
Material examined. CANADA: British Columbia, Marion Lake, pupal exuviae, 1964, A. L. Hamilton. Lake Winnipeg records: Victoria Beach, 219 males, 9. & 25. vii. 1969; Pine Dock, 6 males, 10. & 31. vii. 1969; 0.5 km off George Island, 10 males, 11. vii. 1969; 3 km off Grand Rapids, 28 males, 13. vii & 4. x. 1969; 10 km off (Sturgeonskin) Long Point, 22 males, 14. vii. 1969; 3 km off McCreary Island, 14 males, 15. vii. 1969; Gull Harbour, 5 males, 1 female, 16. vii. 1969; Gimli Government Wharf, 3 males, 24. vii. 1969; Matheson Island Government Wharf, 1 male, 26. vii. 1969; 3 km off George Island, 46 males 27. vii. 1969; Grand Rapids Government Wharf, 16 males, 28. vii. 1969; 5 km of Selkirk (Horse) Island, 58 males, 29. vii. 1969; McBeth Harbour, 123 males, 7. ix. 1969; 15 km east of Long Point, 1 male, 6. ix. 1969; 20 Mile Creek, 1 male, 1. ix. 1971; Old Fishing Dock, 9 males, 21. vii. 1971; Calder’s Dock, 22 males, 6. & 14. vi. 1971; Hecla Island, 10 males, 27. vii. & 11. viii. 1971; Beaver Creek, 1 male, 13. vii. 1971; South Basin, 31 larvae, 4. vi. – 31. x. 1969; Narrows, 9 larvae, 4. vi. – 31. x. 1969; North Basin, 41 larvae, 1 pupa, 4. vi. – 31. x. 1969. The Lake Winnipeg males have an AR of 3.54 – 4.03, 3.80 (10); a LR 1 of 1.23 – 1.39, 1.30 (10); 9 – 24, 14 (10) sensilla chaeticae on mid leg, none on hind leg; and 24 – 40, 32 (10) setae on squama. A female has 75 sensilla chaeticae on mid leg, 34 on hind leg. Its genitalia are illustrated in Saether (1977 b fig. 90 A, B). Pupa (n = 1 – 2, tentatively associated and not reared) Total length 10.34 – 10.84 mm. Cephalothorax. Cephalic tubercle (Fig. 3 C) 270 – 285 µm long, 46 µm wide 1 / 3 from base, 40 µm wide 2 / 3 from base, with or without a 20 µm long frontal seta.