Species e.  C. melanescens Keyl, 1962

Keyl attributes the species to Strenzke, but Strenzke did not publish any description.
Chironomus melanescens Keyl, 1961 – nomen nudum with no description.

This species is in BOLD BIN: BOLDAAI4303

Adult:

Male:
Comparison to characters of Palearctic specimens (in brackets) where these are available from Wülker et al. (1981):
Wing length 3.74 (3.42-4.66) mm, width 0.99 mm.  AR 3.7 (3.20-4.58).  LR 1.52 (1.42-1.58), Fe1/Ti1 1.05 (1.00-1.11); BR 2.0-2.2 (1.5-3.0).

Additional data from Nearctic male:
Length/width of frontal tubercles 22 x 10 µm; palpal proportions (micron) 50 :53 : 230 : 255 : 355.  43 clypeal setae.
Thoracic setae: acrostichals at least 13; dorsolaterals 21-43; prealar 5-6; supraalar 1-2, scutellars in approximately three rows, posterior row with 19 setae, other two rows less clear and with 25 setae between them.
Three SCf on branchiolum of wing, 26 setae in squamal fringe.
Leg proportions (microns):

 
Fe
Ti
Ta1
Ta2
Ta3
PI
1400
1330
2025
995
835
PII
1455
1405
880
500
365
PIII
1710
1745
1335
735
580
 
Ta4
Ta5
LR
F/T
BR
PI
755
380
1.52
1.05
2.0-2.2
PII
255
175
0.63
1.04
-
PIII
335
195
0.76
0.76
-

               

Male terminalia of C. melanescens (left) and whole adult (from BOLD Database)(right).  Abdomen showing the pattern of coloration (below).

   

Abdominal tergites with basal brown bands, but extending further along the tergite in the more posterior segments.  Nine (4-16) setae in center of tergite IX, 1 or 2 to a pale patch (see above).
Terminalia similar to that of C. riparius, i.e. superior volsella of the S-type of Strenzke (1959).  Inferior volsella reaching about to midpoint of the gonostylus, with simple setae.  Gonostylus tapers relatively gradually from about two thirds along its length.

Female - no information available.

Pupa typical of the genus, lightish brown in color.  Length about 8.3 mm, posterior margin of wing case 3.5 mm. Cephalic tubercles about 55 µm in length, slightly longer than their basal diameter.
Basal ring of respiratory organ abt 56 x 48 µm, prealar tubercle weakly developed, about 50 µm in length.
About 51 recurved hooks on posterior margin of segment II, hook row approximately half of width of the segment.  Light shagreen pattern particularly near the centerline towards the rear of the segments, small muscle marks on segments I-III; obvious pedes spurii B on segment III and large pedes spurii A on segment IV; posterolateral spurs of segment VIII with 1-2 spines.  Hair fringe with about 75 taeniae on each side of the anal lobe.

Larva a medium sized (length, female abt 13.-16.5 mm, male 10.3 mm) bathophilus-type with ventral tubules of equal length (ant. 0.8-2.75 mm; post. 0.8-2.73 mm), anal tubules (Fig. g) long, about 6 times longer than wide.
Gular region pale to slightly dark, frontoclypeus pale to slightly darkened.
Mentum (Fig. c) with pointed teeth; 4th laterals hardly reduced (type I); c1 tooth long and narrow with c2 teeth well separated (type III).
Ventromentum (Fig. d) with about 37 - 43 not very obvious striae, VMR about 0.35-0.41.  Pecten epipharyngis (Fig. a) with about 13 - 16 sharp teeth, although those of the Clarence Creek sample were distorted and irregular.
Premandible (Fig. b) with teeth about equally long, unless outer more worn, inner tooth about 1.6-2.0 times the width of outer tooth.
Antenna (Fig. e) with relatively long, narrow basal segment, about 4 (3.9 - 4.3) times as long as wide; ring organ between a third and half way from base of A1; AR about 1.88 - 2.4; ratio of segments (in microns) about 183 ; 43 : 13 : 15 : 9.
Distance between antennal bases greater than that between the S4 setae.
Mandible (Fig. f) with 3rd inner tooth only slightly darkened and hardly separated (type II-IIIB), and with about 11 - 14 furrows on the outer surface at the base.
Ventral tubules of Wisconsin specimens were much longer than those from Omtario.

Cytology:  4 polytene chromosomes with pseudothummi arm combination AE, BF, CD, G.
Arm G generally paired unless heterozygous, with a subterminal nucleolus and 2 Balbiani rings which vary in position depending on the sequence.  No nucleoli in other arms.
Polymorphic at least in arms A, C, and G - these inversions also occur in European populations.  Arm B of North American specimens is inverted compared to the Palearctic sequence.

melA1:    1 - 2c, 10 - 12, 3i - 2d, 9 - 4, 13 - 19;    ie. as holomelas
melA2:    1 - 2c, 10 - 12, 3i - 2d, 16 - 13, 4 - 9, 17 - 19
melB1:    Typical puff (BR) approximately medial                (Palearctic)
melB2:    Typical puff (group 7) near centromere                (Nearctic)
melC1:    1 - 2f, 11c - 10, 16 - 17a, 7d-a, 13 - 11d, 2g - 6, 14 - 15, 8 - 9, 17b - 22. (Palearctic)
melC2:    1 - 2f, 11c - 10, 16 - 17a, 9 - 8, 15 - 14, 6 - 2g, 11d - 13, 7a-d, 17b - 22 (Palearctic)
melD1:    1a-e, 9 - 7, 13c - 10, 1f - 6, 13d - 16, 19e - 23, 19h - 17, 24. (NB. bands 19fg not listed)
melE1:    1a-d, 3f - 11, 1e - 3e, 12 - 13
melF1:    1 - 4b, 15f - 4c, 15g - 23
melG1:    Subterminal nucleolus and 2 nearby BRs.
melG2:    simple inversion near distal end of arm.
melG3:    simple inversion of medial section of arm.

Molecular Data: Sequence for mitochondrial COI and CytB of Palearctic material are available in GenBank (accession numbers AF192204, AF192173) and COI of four NA specimens is also available (accession numbers KT608863, KT608904, KT609554, KT611186), as well as further sequences in the BOLD database.

Found: Ontario – Clarence Creek (45.50°N, 75.22°W), Russell Co.; Dunrobin (45.45°N, 76.00°W), Carleton Co.; Blair Rd Public School,
            Cambridge (43.3718°N, 80.327°W) (BOLD BIOUG13119-C10); rare Charitable Research Reserve (43.3705°N, 80.3641°W),
            Cambridge. (Telfer et al. 2015); Howick Central Public School, Gorrie (43.884°N, 81.053°W) (BOLD BIOUG13107-G1); Saunders
            Secondary School, London (42.947°N, 81.289°W) (BOLD BIOUG13007-E01); Notre Dame Catholic School, Orillia (44.61°N,
           79.461°W) (BOLD BIOUG13120-A02); Thousand Islands Natl. Park (44.453°N, 75.865°W) (BOLD BIOUG20486-E04); Toronto Zoo,
           Rouge National Urban Park (43.822°N, 79.19°W), Toronto (BOLD BIOUG20014-G11).
            Prince Edward Island - Cavendish Grove, Prince Edward Island Natl. Park (46.493°N, 63.394°W) (BOLD BIOUG20330-B12).
            Wisconsin – Arboretum, Madison (43.03°N, 89.42°W), Dane Co.; Trout Lake Limnol. Stn. 41.02°N, 89.67°W), Vilas Co.
            Germany: Clausthal (Zellerfeld)(locality of type ) and Duemmer Lake.
            Switzerland and Russia.

Adults and larvae partly described by Wülker et al. (1981), who also described the cytology, and Kiknadze et al. (1991) also redescribed the larva and cytology (with minor errors in arm E); Kiknadze & Broshkov (2009) redescribe the cytology of European and Asian specimens.  Martin (2015) describes morphology, karyotype and Barcode of North American specimens.

            Temporary pools, especially snow melt pools.

See also  C. sp. z,  C. sp. 2t,  C. sp. 3l.

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Modified: 24 March 2021
Access: Unrestricted
Copyright © 2000-2021, Jon Martin.