Species 3e. Chironomus (Chaetolabis) ochreatus Townes, 1945.

In BOLD Bin: BOLD:AAP5112

Adult:

Male terminalia of C. (Chaetolabis) ochreatus.
Note the club shaped superior volsella.

Antenna (left) and ventral abdomen (right) of C. (Chaetolabis) ochreatus female.

Pupa:  Length of exuvia about 10.3 mm (male), inner margin of wing case about 2.04 mm; color yellowish brown; with well developed narrow cephalic tubercles (70 x 20 µm) arising from a broad base, with subapical seta about 56-58 µm long; also a large secondary tubercle or frontal wart about 56-68 µm long and 43-48 µm wide at the base.
Basal ring kidney shaped, about 177 x 82 µm, i.e. l/w about 2.1-2.2; 2 vacuoles slightly anterior to it. Abdomen with a central patch of shagreen on segments II-V, grading from posterior 2/3 on seg. II, to whole length of segment on segment V; on segment VI the shagreen is restricted to the anterior third.
Pedes spurii B on segments II and III small; PsA on segment IV 243 µm long ((0.25 of segment length) and 134 µm wide.  Numbers of L-setae on segments II-IV also as usual, the posterior two on segment IV arising reasonably separated.
Hook row on segment II with about 93 hooks, occupying about 42% of width of segment.
Posterolateral spur of segment VIII with 1-2 large spines with 0-3 small spines at their base, all spines closely applied and main spines extended to a fine curved point.  About 142 taeniae in multiple rows on each side of anal lobe.

Fourth instar larva a medium sized thummi-type; length about 12.8-16.8 mm (Female 15.5 (14.8-16.8) mm; male 14.1 (12.8-15.3) mm); posterior pair of ventral tubules longer and coiled (ant. 1.34 (1.21-1.57) mm; post. 1.50 (1.41-1.81) mm), those of the Quebec specimens much shorter than those from Wisconsin.  Anal tubules very large, about 4.5-6.4 times longer than wide, with a constriction about one third from the base (dors: 1120 x 200 µm, vent: 1180 x 170 µm).
Gula region and frontoclypeus usually pale, but some specimens have very slight darkening of both.  Width of frontoclypeus between the antennal bases (ASA of Vallenduuk & Moller Pillot, 1997) about 186-190 µm, greater than the distance between the S4 setae (about 160-175 µm).  Oesophageal opening about 83.5 µm wide and 3.7 times wider than deep.
Mentum (Fig. d) with relatively pointed teeth;  c1 tooth moderately broad with short parallel sides, c2 teeth moderately well seperated (type IB).4th laterals hardly reduced (type I); 6th laterals arising at about the same level as other teeth.
Ventromental plates (Fig. e) about 248-250 µm wide and 3.06-3.38 times wider than deep and 1.08-1.09 times the mentum width; separated by about one third of the mentum width; with about 39-45 striae (Webb et al. 1987).
Premandible (Fig. b) with relatively sharp inner tooth, about 4-5 times wider than the narrow, sharp outer tooth (type 2B).  Pecten epipharyngis (Fig. c) with about 23.2 (21-25) irregular teeth, with small interstitial teeth (type D).
Antenna (Fig. a) with A1 about 35-44% of the VHL; A2 long, over 1/3 length of A1, which itself is about 3.3-4.3 times longer than wide; ring organ a third to almost half way up from the base; AR 1.95 (1.50-2.27; antennal segment proportions (micron) 154 : 44 : 11 : 18 : 8. i.e. A5 about same length as A3.
Mandible (Fig. f) with 3rd inner tooth partly separated and only moderately pigmented (type IIB); with about 19 (17-2) furrows on outer margin at base; Pecten mandibularis of 13.2 (12-15) taeniae; Mdt-Mat about 28, MTR 0.31-0.47.

Cytology:  3 polytene chromosomes which may have the modified thummi arm combination, AB, CD, GEF; but Keyl pattern very difficult to recognize.
Nucleolus near the junction of arm G with E, arm G generally unpaired;  2 Balbiani rings between nucleolus and end of arm, with another in arm E, found in some cells of one larva only.  No nucleolus in the long chromosomes.
Polymorphism in arms B and F.

Found:  Quebec – Lake Opasatica, Rouyn-Noranda (48.17; -79.33).
            Arkansas – Galloway (Townes); White River National Wildlife Refuge, Arkansas (Chordas et al. 2004.)
            Georgia - roadside pond (B. Caldwell, in Epler 2001)            Maine – Lincoln Co. (Townes)
            Massachusetts – Holliston (Townes)
            Michigan – Empire (Townes)
            New Jersey – Medford Lakes (Type locality); Chesilhurst; Glassboro (Townes)
            New York -– Lake Sebago, Bear Mountain State Park (Townes)
            Rhode Island – Westerly; Wickford (Townes)
            South Carolina – Greenville, Table Rock State Park, Pickens Co. (Townes)
            Virginia – Four-mile Run; Norfolk Co. (Townes)
            Wisconsin – Little John Jr Lake, Vilas Co. (46.00°N, 89.63°W); Mud Lake, Vilas Co. (46.02°N, 89.62°W).

            At depth of about 4 m amongst Drepandocladus exannulatus, and in pools.

Wiederholm (1979) considered Ch. ochreatus to be a synonym of Ch. atroviridis, but did note that this was subject to confirmation by further analysis.  The presence of the large secondary tubercles in the pupa (above) shows that it is clearly distinct.  Detailed features of the larval ventromental plates are given by Webb et al. (1987).

DNA analysis: Sequence for the mitochondrial CO1 and the nuclear gb2β genes are available.
CO1: Gene bank accession numbers KF278327; KF278328; KF2788351.  Also Barcode sequences in BOLD database.