Oriental Chironomus: C. brevistylus

Chironomus brevistylus Guha et al. 1985.

Adult:

Male:
Body length 4.73 mm, wing length 2.1 mm), wing width 0.57 mm.  Antenna missing.
Head yellow; vertex with 11 setae; 20 clypeal setae, clypeal ratio 1.2.  Maxillary palp brown, ratio of segments: 10 : 11 : 40 ; 50 : 64; P5/P4 1.28; P5/P3 1.63.  Frontal tubercles well developed.  CA 0.68, CP 1.15.
Frontal tubercles well developed, about twice as long as wide.  Lateral pronotal setae absent.
Thorax yellow, antepronotum collar-like without v-shaped emargination; postnotum yellow and bare.
Setae: 2 Acrostichal; 9 Dorsocentral; 4 Prealar; 10 Scutellar.
Wing: 2 Scf on brachiolum, 13 setae in squamal fringe.  Dark spot on fCu.  CR 0.97, VR 1.05.
Femur and tibia of all legs yellow, tarsomeres of fore and hind legs missing from type, TI-III of midleg with apical brown band, rest brown, LR1 2.1; LR2 0.68; LR3 0.64.
Ta4 of anterior legs noted as unusually long (from paratypes).
Abdomen yellow and terga uniformly setaceous.  Anal point slender with apex blunt.  Gonocoxite with 16-18 setae; gonostylus short and stout, coming to a narrow point (hence name).
Superior volsella closest to E-type of Strenzke (1959); Inferior volsella short and wide, extending barely past the base ot the anal point and the gonostylus, shown with simple setae.
Ground color of scutum yellow, scutal stripes reddish brown, scutellum yellow, postnotum dark brown, halteres yellow; wings unmarked, r-m dark brown.
In all legs, femur and tibia are entirely yellow, tarsi I, II and III largely yellow and each with an apical dark ring, tarsi IV and V largely dark brown; ground color of abdominal tergites greenish yellow, tergites I to VII each with a large central dark patch which is almost triangular in tergites II to IV (Fig. below); tergites VIII and hypopygium dark brown.    Hypopygium (see Fig. 1, below). Ninth tergite with 12-16 long setae in the middle.  Anal point slender and slightly expanded apically.  Superior Volsella (Fig. I below) composed of a relatively high, triangular base bearing several long setae, and a hook-like apical process.  Inferior Volsella (Fig. 1, below) relatively short, stout and almost parallel-sided, with 14 long and recurved setae arising from apical 1/5.  Gonostylus abruptly narrowed at about apical 1/3.

Male hypopygium (left) of C. brevistylus
From Guha et al. 1985.

Female:
Body length 4.07 mm, wing length 2.07 mm, width 0.66 mm.
Femur and tibia brown, TI-III with brown aical band, rest of all legs brown.
Antenna pale, seg. V longest and brown, ratio of flagellomeres I-V 9 : 7 : 7 : 8 : 12. AR 0.26; A5/A1 1.33.
Genitalia: Notum 0.15 mm. Coxosternapodeme incurved. Gonapophysis VIII divided into a broad posteriorly directed dorsomesal lobe, hooked ventral lobe and needle-like apodeme lobe. Gonocoxite IX with 4 setae on each side. Postgenital plate protruded and pointed at apex. Seminal capsules oval, measuring 0.06 mm by 0.039 mm, ducts bent and open separately.

Notes some similarity to C. javanus and C. vitellinus.

Holotype male (no. 129, B.U. Ent.), India, Andaman Island, old wandor, 17.v.1982. Coll. Dr. R. Sharma.
Allotypes: 9, data as holotype, paratypes 2 males, 2 females, collected same locality.

[ Return to Index |