Chironomus Greiner Lake species,

Known from 2 larvae from Greiner Lake (sample #17), Victoria Island, Nunavut.
Available DNA sequence does not match anything in GenBank or the BOLD database, closest is C. salinarius with about 92% similarity.

Adult and Pupa not known.

Fourth instar larva:  A halophilus-type larva, length about 14.2-15.8 mm; no LP; posterior VT about 0.48-0.56 µm.  Anal tubules a single lobe, dorsal (len. about 280 µm and about 2-2.2X longer than wide), shorter than ventral (len. about 320-360 µm and 2.3-3.2X longer than wide).  Gula dark on posterior 1/3-1/2; Frontoclypeus slightly dark with a streak, and outside a slightly dark line.
Mentum (Fig. d) quite wide compared to VHL (about 0.74 VHL length) with 4th laterals reduced to at least the level of the 5th laterals (type III), center tooth probably type III, with c1 quite wide on one larva.
Ventromental plates (Fig. e) separated by about 0.34-0.38 of mentum width, with about 38-40 striae; VMR about 0.28-0.36.  Pecten epipharyngis (Fig. a) with about 13-14 somewhat irregular teeth and smaller teeth at the outside edges (type C).
Premandible (Fig. c) possibly with outer tooth longer and inner tooth about 3 times wider.
Distance between the antennal bases larger than that between the S4 setae, which are separated from each other by 80% of frontoclpeus width.
Antenna (Fig. b) has A1 about 3.5 times longer than wide and equivalent to about 45% of VHL, DRO about 0.4-0.5 up from base of segment; AR abt 2.14-2.33; antennal proportions (micron) 154-158 ; 37-40 : 8 : 15-17 : 7-8.
Mandible (Fig. f)with third inner tooth partly or completely separated and partly colored (II-IIIB); 15-19 furrows on the outer surface at the base; 11 setae in Pecten mandibularis.

Cytology:  Cytology of available specimen relatively poor, but some information was obtained:
4 polytene chromosomes with the thummi-cytocomplex arm combination AB, CD, EF, G.
Nucleolus terminal or subterminal on arm G; there could be a BR about a third from the other end.  A second nucleolus is between the centromere and the "olive" of arm A.
End of arm B unpaired, possibly due to inversion heterozygosity but the sequence is not clear enough to be certain.

Found: Nunavut - Greiner Lake, Victoria Island (69.19°N, 104.93°W).

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Created: 13 October 2018
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Copyright © 2018, Jon Martin.