Key for the Major Taxonomic Groups*

Walker, I.R. (1988). Late-Quaternary Palaeoecology of Chironomidae (Insecta: Diptera) in Lake Sediments from British Columbia. Ph.D. thesis, Simon Fraser University, Burnaby, B.C.

1. • a) Ligula and retracted 1st antennal segment retained in most fossil head capsules; mentum small, inconspicuous, and weakly pigmented (Fig. 1, 2)
     .............................................................................SUBFAMILY TANYPODINAE
     
     
   • b) Head capsule without ligula; antennae non-retractile; mentum conspicuous and, in most taxa, darkly pigmented (Fig. 3, 4, 5, )
     .............................................................................2.
   
   
   
   
2. • a) Mentum concave; ventromental plates vestigial (Fig. 3)
     .............................................................................Stenochironomus
     
     
   • b) Mentum convex (Fig. 5); or if concave, then ventromental plates conspicuous (Fig. 4).
     .............................................................................3.
   
   
   
   
3. • a) Ventromental plates very broad, always extending laterally far beyond the outermost mental teeth; ventromental plates striated (Fig. 4).
     .............................................................................SUBFAMILY CHIRONOMINAE
     
     
   • b) Ventromental plates much smaller, not extending far beyond the outermost mental teeth (except in Nanocladius and Stilocladius); ventromental plates never striated (Fig. 5)
     .............................................................................SUBFAMILIES DIAMESINAE, PRODIAMESINAE, ORTHOCLADIINAE AND PODONOMINAE
   
   
   
   

Fig. 1. Procladius (Subfamily Tanypodinae).

Note the retracted first antennal segments, and the fork-shaped ligula. Both features occur only in members of the subfamily Tanypodinae. The head capsules of the Tanypodinae are weakly-pigmented, being only very weakly sclerotised.

Fig. 2. Tribe Pentaneurini (Subfamily Tanypodinae).

Note the retracted first antennal segments, and the fork-shaped ligula. Both features occur only in members of the subfamily Tanypodinae. The head capsules of the Tanypodinae are weakly-pigmented, being only very weakly sclerotised.

Fig. 3. Stenochironomus (Subfamily Chironominae).

Note that Stenochironomus differs from all other representatives of the subfamily Chironominae in having very poorly developed (vestigial) ventromental plates. The concave mentum is another unusual feature, occurring only in a few other genera of chironomids (e.g., Cryptochironomus). Like most chironomids, apart from the Tanypodinae, the mentum is the most strongly pigmented, and thus, the most conspicuous feature on the head capsule.

Stenochironomus larvae burrow in submerged wood.

Fig. 4. Dicrotendipes (Subfamily Chironominae).

Like all members of the subfamily Chironominae (apart from Stenochironomus), Dicrotendipes has very prominent ventromental plates. The ventromental plates of the Chironominae are also striated, although the striations are often less conspicuous than those apparent in the photograph shown below.

Like most chironomids, apart from the Tanypodinae, the mentum is the most strongly pigmented, and thus, the most conspicuous feature on the head capsule.

Fig. 5. Heterotrissocladius marcidus (Subfamily Orthocladiinae).

In Heterotrissocladius, like most members of the subfamilies Orthocladiinae, Podonominae, Diamesinae, and Prodiamesinae, the ventromental plates are smaller, less conspicuous than those of the Chironominae. The ventromental plates are never striated.

Like most chironomids, apart from the Tanypodinae, the mentum is the most strongly pigmented, and thus, the most conspicuous feature on the head capsule.