Species 3o. C. entis Shobanov, 1989

as is Chironomus plumosus.

Adult essentially similar to C. plumosus.  Shobanov claims differences exist in Palearctic specimens, but these have not been confirmed in the Nearctic.  No description of the adults or pupae of the Nearctic specimens appears to have been published, so the data for Palearctic specimens from Shobanov (2005) will be used.

Male: Body length generally larger than C. plumosus, but ranges overlap; AR 5.52 (5.09-6.29).
Clypeal setae 75.9 (61-92).  Palp segs (3-5) µm: 339 : 375 : 534.Thoracic setae: Dorsolaeral 90.3 (77-115); Scutellar 101.4 (79-130).
Selected leg measures (mm) and ratios:


About 9-13 setae on TIX, mostly in individual clear spots; Superior volsella possibly closest to E(g) of Strenzke (1959); Inferior volsella relatively long, extending just beyond the end of the anal point and about two thirds of the length of the gonostylus, which narrows relatively sharply over posterior third.

From Shobanov (2005)

Fourth instar larva a large (female: 21.3-22.8 mm; male 18.3-23.4 mm), generally semireductus-type, anterior ventral tubules straight and tapering only near the tip (Butler, unpubl.).  The ventral tubules are generally shorter (ant. 0.26-0.8 mm; post 0.17-0.68 mm) than those of C. plumosus, with anterior pair longer.  The ventral tubules also seem to be quite variable in length between localities, with those from Lake Waskesiu, Saskatchewan much shorter (ant. 0.26 mm; post. 0.17 mm) than those of other localities for which measurements are available. Lateral projections relatively short (90-220 µm).

Anal tubules of C. entis

Anal tubules well developed, about 2.5-2.75 times longer than wide.

Photos courtesy of M.G.Butler and I. Proulx.

Gula dark-very dark on basal 2/3 and up to ventromentum, with a rough edge; fronyoclypeus pale.
Mentum (Fig. c) with 4th laterals hardly reduced (type I) and the central tooth with separated c2 teeth, either type IIA or possibly a worn type III.
Ventromentum (Fig. d) about 3.9-4.7 times wider than deep with a slightly jagged edge Fig. f); VMR about 0.24 (0.20-0.26); separated by about 0.33-0.41 of mentum width and 1.06 (1.02-1.15) times the mentum width.
Pecten epipharyngis (Fig. a)with about 14 (10-17) teeth of type B; epipharyngeal opening apparently wider (sometimes arched) than that of C. plumosus, about 4 (3.56-5.6) times longer than wide.
Premandible (Fig. b) with relatively narrow teeth, inner tooth about 1.5-3 times wider than the outer tooth.
Antenna (Fig. g) with basal segment slightly longer than that of C. plumosus 3.82 times longer than wide but with considerable overlap in range; RO slightly above the middle of the segment (0.54-0.78 up from base); AR 2.82 (2.43-3.25); relative length of segments (micron): 216 : 41 : 11 : 15 : 9, A3 longer than A5 in all studied specimens.
Distance between antennal bases generally greater (288µm) than that between the S4 setae (261 µm) which are separated by about 0.81 (0.79-0.82) of the FC width.Mandible (Fig. e) with third inner tooth well developed and and darkened (Type IIIC), with about 29 (24-35) furrows on outer surface near the base; and 15.2 (13-18) taeniae in the Pecten mandibularis.
Anal tubules well developed, about 2.5-2.75 times longer than wide.

Cytology:  4 relatively short polytene chromosomes with thummi arm combination AB, CD, EF,G.  Very similar to C. plumosus.
Arm G more commonly partly paired, with a large virtually terminal nucleolus; Balbiani ring near middle of arm below the nucleolus.
Arm A most commonly with the Holarctic sequence A4.    Polymorphism in arms A, B, D, E and F.
h'entA4:    1-2c, 10-12a, 13ba, 4a-c, 2g-d, 9-4d, 2h-3, 12cb, 13c-19
n'entA11:  1-2c, 10-12, 14f-13, 3-2h, 4d-9, 2d-g, 4c-a, 14g-19                        from h'ent A1
n'entA12:  1-2b, 12a-10, 2c, 12bc, 14f-13, 3-2h, 4d-9, 2d-g, 4c-a, 14g-19            from A11
n'entA13:  1-2c, 10-12, 14f-13, 3-2h, 4d-9, 2d-g, 4c-a, 14g-i, 17d-15, 17e-19        from A11
n'entA14:  1-2c, 10-12, 14f-13, 3-2h, 4d-9, 2d-g, 4c-a, 14g-i, 17-15, 18-19            from A11
n'entA15:  1-2c, 10ab, 7d-9, 2d-g, 4c-a, 13ab, 12a, 11-10c, 7c-4d, 2h-3, 12cb, 13c-14, 17-15, 18-19        from A4 & recomb with A14.
h'entB1:    Balbiani ring near distal end of the arm. Differs by simple inversion from h'pluB2
n'entB5:    Larger inversion moving BR to middle of arm
n'entB6:    Small submedian inversion
n'entB7:    Small proximal inversion
n'entB8:    Slightly larger proximal inversion
n'entC3:    1a, 11h-d, 6gh, 17a, 16h-a, 7-6c, 2c, 5-6b, 11c-8, 15-12, 1b-2b, 4-2d, 17b-22
h'entD1:    1-2d, 15e-16c, 18cd, 8-10a, 13a-12, 18ba, 7-4, 10e-b, 13b-15d, 2e-3, 11a-c, 16d-17, 18e-24
n'entD4:    1-2d, 15e-16c, 18cd, 8, 19-18e, 17-16d, 11c-a, 3-2e, 15d-13b, 10b-e, 4-7, 18ab, 12-13a, 10a-9, 20-24
h'entE1:    1-2b, 11b-10c, 3f-4, 10b-5, 3e-2c, 11c-13;            i.e. as muratensis
(alt. E1):    1-2b, 11b-10c, 3f-4b, 3b-e, 10b-4c, 3a, 2e-c, 11c-13        (see Kiknadze et al. 2000)
n'entE5:    1a-g, 10c-11b, 2b-1h, 3f-4, 10b-5, 3e-2c, 11c-13 (from alt E1)
n'entEF(E6+F5):  simple pericentric invsion of about Egp6 - Fgp7
Arm F1:    1a-d, 6-1e, 7-10, 17-11, 18-23
Arm F4:    1a-d, 6-1e, 19-18, 11-17, 10-7, 20-23;            i.e. as plumosus F3
h'entG1:n'entG3:    differs by small distal inversion.

Found: British Columbia - Near Opposite Crescent, Bechers Prairie, Cariboo and Chilcotin Parklands (Canning);
            Manitoba - Winnipeg (P. Chang); Lake Winnipeg (Sæther 2012).
            Ontario - Bay of Quinte, Belleville )(O. Johannsen); White Lake, Three Mile Bay (48.70°N, 85.67°W) (D.R. Oliver);
            Quebec - Lake D'Alembert (48.38°N, 79.03°W), Lake Dasserat (48.28°N, 79.42°W), Lake Marlon (48.27°N, 79.07°W),
            Lake Opasatica (48.17°N, 79.33°W) and Lake Pelletier (48.22°N, 79.05°W).
            Saskatchewan - Lake Waskesiu (53.92°N, 106.08°W), Prince Albert National Park; Crooked Lake, Pasqua Lake, and Round Lake,
            Qu'Appelle River (all W. Warwick).
            Indiana - Crooked Lake (41.40°N, 85.02°W), Angola Co.; Manitou Lake (41.0353.92°N, 86.1153.92°W), Fulton Co.
            Michigan - Saginaw Bay, Lake Michigan (43.45°N, 83.67°W), Bay Co.
            Minnesota - Lake Itasca; Lake Christina (46.08°N, 95.75°W), Douglas Co., (46.79°N, 96.28°W) Kiknadze et al. 2000).
            North Dakota - Blacktail Dam (48.26°N, 103.44°W), Williams Co.; Brewer Lake (47.25°N, 97.77°W); Fuller Slough
            (47.32°N, 97.77°W), and South Golden Lake (47.31°N, 97.50°W), both Steele Co.; Crooked Lake (47.39°N, 100.54°W), McLean Co.;
            Dead Colt Creek Dam (46.43°N, 97.68°W), Ransom Co.; McVille Dam (47.77°N, 98.17°W), Nelson Co.; Lake Elsie
            (46.04°N, 96.53°W), Richland Co.; Lake Isabel (46.49°N, 99.40°W), and Lake Williams (47.06°N, 90.17°W), both Kidder Co.;
            Lake Metigoshe (48.57°N, 100.22°W), Bottineau Co.; Red Willow Lake (47.88°N, 98.40°W), Griggs Co.; Silver Lake
            (46.05°N, 97.95°W), Sargent Co.; Warsing Dam (47.83°N, 99.12°W), Eddy Co.; Wilson Dam (47.06°N, 99.40°W), Dickey Co.
            Oklahoma - Buncombe Creek, Marshall Co.
            South Dakota - Lake Alice (44.53°N, 96.38°W), Deuel Co.
            Wisconsin - East Horsehead Lake (45.42°N, 89.37°W), and Pine Lake (45.49°N, 89.55°W), both Onieda Co.; Grand Portage Lake
            (46.10°N, 90.80°W), Iron Co.; Green Lake (43.72°N, 89.00°W), and Little Green Lake (43.44°N, 80.59°W), both Green Lake Co.;
            Lake Kengonsa (42.977°N, 89.205°W), Dane Co.; Pepin Lake (44.26°N, 92.09°W), Pepin Co.; Pleasant Lake, (42.47°N, 88.33°W),
            Walworth Co.; Winnebago Lake 44.01°N, 88.27°W), Calumet Co. (W. Hilsenhoff); Yellow Lake (45.55°N, 92.24°W), Burnett Co.

            Found in lakes, often with C. plumosus.

Cytology described by Kiknadze et al. (2000a, & b) and arm A revised by Golygina and Kiknadze (2008);    larva described by Shobanov (1989a, & b).
Kiknadze et al. (1991) describe the outer hooks on the anterior margin of the ventromentum as being longer and sharper than those of C. plumosus in Palearctic populations, but does not seem to apply for North America - besides being very difficult to see.  Although the ventral tubules are generally shorter than those of C. plumosus, and where the two species occurred together at Lake Itasca, MN, the two species could be accurately separated on this character, in general there is considerable overlap, and could only be used with confidence if less than 0.4 mm in length.   Shobanov (1989b) notes that the basal antennal segment of C. entis (abt 210 µm) is longer than that of C. plumosus (abt 167µm), making the other segments appear relatively shorter than those of C. plumosus (100:18.5:5:7:4 cf. 100:23:7:9:5), while C. vancouveri has relatively shorter segments III, IV and V (100:21:4:6:3).
C. entis and C. plumosus cannot be separated on the basis of the DNA "barcode" sequence of COI, or CytB (Guryev et al. 2001) but can be separated by the sequence of the globin gene gb2Β (Guryev and Blinov 2002).

See also C. plumosus, C. balatonicus,C. muratensis, and C. vancouveri

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Modified: 7 June 2021
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