Fourth instar larval types of Chironomus

Nine larval types are recognised, based on the presence or absence of posterolateral (PLT) and ventral tubules (VT) of the 10th and 11th body segments. The following classifications are based on Proulx et al. (2013).

The categories are:
                Lacking PLT and VT:
                    salinarius (Fig. 9)

                Lacking PLT on segment 10:
                    halophilus - anterior VT very short or absent, posterior VT short (Fig. 8).
                    bathophilus - moderate to long, essentially straight VT.
                    fluviatilis - VT slightly curved and coming to a point at ends.
                    thummi - long, anterior VT with 'elbows', posterior VT coiled (Figs. 6 & 7).

                Possessing PLT on segment 10:
                    reductus - lacking ventral tubules.
                    semireductus - short straight or slightly curved VT.
                    melanotus - moderate to long, essentially straight VT.
                    plumosus - long, anterior VT with 'elbows', posterior VT coiled (Figs. 4 & 5).

From Andersen (1949)