Dicrotendipes Kieffer, 1913

Cranston, Peter S., 2007, The Chironomidae Larvae Associated With The Tsunami-Impacted Waterbodies Of The Coastal Plain Of Southwestern Thailand, Raffles Bulletin of Zoology 55 (2), pp. 231-244 : 239

Dicrotendipes Kieffer

( Figs. 37–42 )

Dicrotendipes is one of the few genera to have been studied adequately in the region, thanks to the work of Epler (1988). Three widely-distributed species are recognised that can be distinguished using the keys of Epler (1988) and Cranston (2000). Dicrotendipes pelochloris (Kieffer) , whose immature stages were described as Cladotendipes inferior (Johannsen) by Lenz (1937), occurs in several post-tsunami impacted ponds. All larval occurrences were in recovering or minimally-impacted ponds, of conductivity 169–897 µS. cm−1 and dissolved solids of 84–449 ppm.

The immature stages of D. septemmaculatus (Becker) have been described by Epler (1988) and Cranston (2000). The species has been reported regionally from Lake Toba, Sumatra (Kikuchi & Sasa 1990). Larvae of D. septemmaculatus were found in three dilute pools (104–192 µS. cm−1 conductivity, dissolved solids 92–96 ppm).

One larva apparently conspecific with those identified as D. ‘ sarinae /K4’ from northern Australia ( Cranston, 2000) was found in a moderately impacted pool recovering 18 months post-tsunami (440 µS. cm−1 conductivity, dissolved solids 222 ppm).

These three species can be distinguished as larvae as follows:

1. Frontal apotome of dorsal head with ovoid fenestra ( Fig. 37 ). Outermost mental teeth composite and fused ( Fig. 40 ) ......... .......................................................................... D. pelochloris

– Frontal apotome of dorsal head without such ovoid fenestra ( Figs. 38, 39 ). Outermost mental teeth separate apically ( Figs. 41, 42 ) .................................................................................. 2

2. Frontal apotome with narrow, elongate process ( Fig. 38 ) ...... ................................................................. D. septemmaculatus

– Frontal apotome without indication of fenestra or process ( Fig. 39 ) ............................................................................... D. ‘K4’

Dicrotendipes larvae are collector-gatherers: larvae of some species will tolerate quite high nutrient and salinity levels.

Figures

Figs. 37–47. Thai post-tsunami Chironomidae. Dicrotendipes spp.: dorsal heads: 37, D. pelechloris; 38, D. septemmaculatus; 39, D. sarinae. Mentum and ventromental plate: 40, D. pelechloris; 41, D. septemmaculatus; 42; D. sarinae. Kiefferulus spp., dorsal head sclerites: 43, K. longilobus; 44, K. calligaster; 45, K. barbatitarsis. Mentum, ventromental plate, anterior cardo: 46, K. calligaster, 47, K. barbatitarsis. Abbreviations: cly, clypeus; fen, fenestra; sc1–4, labral sclerites 1–4; vmp, ventromental plate.