North American Chironomus: C. (Loboch.) austini

Species 4h. Chironomus (Lobochironomus) austini (Beck & Beck), 1970

Einfeldia austini - transferred to Chironomus (Lobochironomus) by Epler (2001, p.1.03).

Descriptions based on Beck and Beck (1970)

Adult

Male

Male terminalia and frontal tubercles of C. (Lobochironomus) austini (Photos courtesy of J.E. Sublette).

A brownish, ochraceous species.  Frontal tubercles twice as long as basal width.
Thorax light brown, mesonotal vittae, scutellum and sternum medium brown to ochraceous, postnotum almost black.
Thoracic setae: dorsocentral - about 10; prealar - 3.
AR - 2.76, wing length 1.95 mm.
Legs - darker at apices of tibae and of tarsal segments brown.  Fore tarsus apparently without beard, fore LR 1.9-2.0.
Setae on TIX in several pale areas (appear diamond shaped in above photograph).
Hypopygium as in figure.  Superior volsella closest to an E-type, but not really as any of Strenzke's illustrations.  Anal point narrow but broadens at distal end. Inferior volsella reaching to end of anal point and midpoint of gonostylus, with setae only at tip.  Gonostylus moderately swollen and narrows markedly from just after midpoint.

Pupa: About 5.7 mm long, brown in color. Cephalic tubercles (e, below) fairly large, with preapical bristle.
Tergite I bare, II with median longitudinal band of shagreen and posterior row of approximately 60 hooks. Tergites III-V with broad median longitudinal shagreen band; VI with antero-lateral patches of shagreen, and VIII with an area of fine shagreen on either side of midline; lateral filaments on V-VIII: 4-4-4-4.
Caudolateral spur of segment VIII with a single spine (f, below).
Anal fins with 44 lateral filaments, plus a small filament near outer margin, about half way from base of fin.

Cephalic tubercle (e), and spur of segment VIII (f), of C. (Lobochironomus) austini. (From Beck & Beck, 1970)

Fourth instar larva with pale head capsule. 2nd laterals of mentum almost fused to 1st laterals (more so than in C. longipes (=(Lobochironomus) dorsalis), 4th lateral teeth reduced about to level of 5th lateral (type II).
Pecten epipharyngis with some thinner teeth interspersed between normal teeth. Premandible with two broad lobes, about equal in length and coming to broad points, but inner tooth perhaps twice as wide as the outer.
Antenna with basal segment about three times longer than wide, Ring organ about half way up the segment; AR about 1.2; ratio of antennal segments 50 : 24 : 6 : 8 : 3.
Mandible with 3rd inner tooth not separated, but possibly darkened to some extent (type IB); furrows on outer surface at base not mentioned; P.mandibularis illustrated with 15 taeniae; MTR about 0.28-0.31.

Larval mouthparts of C. (Lobochironomus) austini
a. Mentum and ventromentum, b. Antenna, c. Premandible, d. Mandible. (From Beck & Beck, 1970)

Cytology: Not known.

Found: Florida – Duval Co. (Type); Morrison Field, West Palm Beach, Palm Beach Co.
North Carolina – Juniper Swamp, Onslow Co. (Epler 2001)
A very similar species, C. antonioi, has been described from Brazil (Correia & Trivinho-Strixino 2007).

Streams associated with swamps, possibly acidic.

All life stages briefly described by Beck & Beck (1970)and some larval characters in Epler (2001).

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