Species r.  C. 'tigris' Butler and Kiknadze

Adult:

Male hypopygium (left) and superior volsella (right) of C. ‘tigris’.

Pupa caudolateral spur of segment VIII with about 5 or 6 spines.

Pupa of C. ‘tigris’
Cephalic tubules (above), spur (below)

Larva a large plumosus-type (length, female: 17.6 - 20.4 mm) with anterior ventral tubule longer (female: Ant. 1.5 - 2.4 mm; post. 1.3 - 2.1 mm).  Gular region completely darkened (see Proulx et al. 2013) and frontoclypeus darkened.
Mentum (Fig. c) with a relatively shallow curve, teeth pointed, 4th laterals reduced (type II); c1 tooth broad with short parallel sides, c2 teeth well developed (type IIA-III).
Pecten epipharyngis (Fig. a) with about 18-19 sharp teeth.  Ventromentum (Fig. d) with about 35 - 39 striae, which extend essentially to outer margin; VMR abt 0.06-0.27 depending whether a faint outer ridge can be seen or whether only the edge where the striae end is visible; anterior margin relatively smooth.
Premandible with teeth about equal in length, inner tooth 2.2 - 3.2 times wider than the outer tooth.
Antenna (Fig. b) with relatively short, broad segment 1, about 2.6 - 2.75 times as long as wide; AR about 2.18; antannal segments (micron) 152 : 31 : 10 : 15 : 8.
Distance between antennal bases greater than that between the S4 setae
Mandible (Fig. e) with third inner tooth separated but still relatively pale (type II - IIIB), about 15-18 furrows on outer surface.

The larva can be most easily separated from the other members of the staegeri group by the smooth anterior margin of the ventromentum and by the lower number of striae 34-46 cf. 60-80, and the shorter PLT.  The FA is also generally darker.  The relatively shallow curve and sharp teeth of the mentum will also help to distinguish it from many species.

Cytology:  2 long polytene chromosomes, banding pattern often unclear.  Arm combination GAB, FEDC.
Nucleoli in the region of arm G and arm D, i.e. one in each chromosome.  Balbiani rings distal to nucleolus in arm G.  Centromere of arm E, along with adjacent proximal bands, translocated to distal end of arm E at junction with arm D, where it presumably forms the functional centromere of this arm.

tigA1:     1 - 2c, 10 - 12, 3 - 2d, 9 - 4, 13 - 19                                                                                   as holA1 and staA1
tigB1:   Puff (group 7) with some distal dark bands near end of chromosome
tigC1:     1 - 6c, 11c - 8, 15 - 11d, 6gh, 17a - 16, 7d-a, 6f-c, 17b - 22                                               as abeC1 and staC1
tigD1:     18?, 19 - 17f, 23ba - 20, E13fg, 1 - 3, 11 - 17c, 8c - 0, 4 - 8b, 23c - 24
tigE1:     D13fg, 1 - 3e, 5 - 10b, 4 - 3f, 10c - 13e, F23f                                                                    i.e. transposition of 13fg to arm D
tigF1:     1a-f, 5c - 1g, 5d - 10, 17 - 11, 18 - 23                                                                                 from pigF1 by Inv 1g-5c and 11-17
tigG1:    similar to staG1, but attaches at nucleolar end and with an extra BR.
(Band numbers in bold indicate the bands to which the the ends of an arm attaches if not a telomeric band)

Molecular data.  There is mtCOI sequence in GenBank (KF278239-53), as well as specimens in BOLD, as Chironomus sp.  Also sequence for gb2β.
This molecular data suggests that C. 'tigris' should be included in the staegeri-group, although it lacks the crenulated margin of the ventromentum seen in the other members of the group.

Found: Ontario - Clarke Lake (45.53°N, -78.27°W), Algonquin Provincial Park
            Quebec - Lake St. Joseph (46.92°N, -71.67°W) (Isabelle Proulx)
            Minnesota - Spearhead Lake, Beltrami Co.; Turtle Lake (46.78°N, -96.17°W), Becker Co.
            Wisconsin - Friedbauer Lake (46.27°N, -91.06°W), Bayfield Co.

            In thick mud at depths around 6 m in lakes.

Proulx et al. (2013) give some key features of the larval morphology, notes on the cytology and relationships of the mtCOI to that of other species.  Cytology is also mentioned in Martin et al. (1974) and Martin (1979), described by Kiknadze et al. (1993) as C. sp. Am1), and by Kiknadze et al. (2016) as C. tigris, attributed to Butler & Kiknadze 2003 (which is only an abstract and so has no valid status).