North American Chironomus: Benthalia(?) natchitocheae

Species 4n. Benthalia(?) natchitocheae (Sublette 1964).

Chironomus (Einfeldia group) natchitocheae - Sublette 1964.
Einfeldia (s.l.) Oliver 1981, Epler 2001

Adult:

Head with frontal tubercle, hypopygium, and Superior volsella (on right).
(Photos courtesy of J.E. Sublette)

Male:
Wing length 2.39-2.70. AR 2.82-3.10. No beard.
Head brownish; frontal tubercles developed; palp segments (2-5): 5 : 12 : 20 : 27; P5/P4 1.35, P5/P3 2.25.
Thorax yellowish brown, vittae, postnotum and sternopleuron blackish brown, mesonotum with a slight central hump. Abdomen entirely blackish brown.
Legs darkened on distal third of femur and on tarsi.
Leg proportions (units):

	Fe	Ti	Ta1	Ta2	Ta3	Ta4	Ta5	LR	F/T	Ta5/Ti
PI	57	40	88	44	34	28	11	1.8-2.2	1.42	0.28
PII	58	50	30	15	10	5	4	0.60	1.16
PIII	60	65	48	23	17	10	6	0.74	0.92

Tergite IX with setae from anterior to distal: about 5 setae almost linear on anterior part, and smaller setae flanking the anal point. Superior volsella with chitinous hook on a pedicel covered with small setae and some longer setae (as above); Inferior volsella with a terminal knob covered in setae and reaching just beyond end of the anal point and to about 1/3 along the gonostylus, which hardly narrows distally; anal point broadening towards the tip.

Female: (Allotype)
Wing length 3.15 mm.
Coloration essentially as in male.
Leg proportions (units):

	Fe	Ti	Ta1	Ta2	Ta3	Ta4	Ta5	LR	F/T	Ta4/Ti
PI	60	45	98	38	33	27	12	2.18	1.33	0.60
PII	65	55	32	16	12	6	5	0.60	1.18	0.11
PIII	68	70	50	23	18	11	8	0.71	0.97	0.16

Pupa Length about 8 mm; almost entirely blackish.
Cephalic tubercle long and pointed with a conspicuous preapical bristle.
Tergite II with posterior row of about 81 upturned hooks.
Postero-laterasl comb on segment VIII with about three spines; caudal fin with about 116 setae in an approximate double row.

Larva One pair of ventral tubules. Gula darkened, apotome without fenestra; dark spot at base of antenna.
Median tooth of mentum, with small notches, projecting far beyond first lateral teeth; 5th lateral tooth of mentum larger than 4th and 6th. Frontoclypeus without fenestra; mandible with 2 inner teeth and wide radial grooves near base;
Pecten epipharyngis composed of three small scales (Epler 2001).
Mandible with 2 inner teeth and wide radial grooves near base;

Epipharyngeal region of paratype larva (above) and SVo of paratype male (below).

Cytology: Not known.

Found: Louisiana – U.S. Fish Hatchery, Natchitoches (Type locality).
South Carolina – Lower 3-runs Creek, Aiken Co.

Common in eutrophic lakes and ponds on the Coastal Plain of the Carolinas, but also occurs in rivers and streams.

Has been included in Einfeldia (sens. lat.) (Epler 2001), and also suggested to be Chironomus (Lobochironomus), but appears to fit into that section of Einfeldia (sens. lat.) for which the name Benthalia has been suggested (which the linear arrangement of the setae on TIX could support), although Cranston suggests it fits best with Fleuria.
All life stages described by (Sublette (1964), partial description and some figures of larva in Epler (2001).