Several 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 from Proulx et al. (2013), who recognize nine categories. However, a number of these types are not known from New Zealand, in particular there are no forms with PLTs.
The categories are:
Lacking lateral and ventral tubules:
salinarius (Fig. 9)
Lacking lateral tubules 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 lateral tubules 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).
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From Andersen (1949)