Medium-sized, up to 11 mm long. Red larvae.
Frontal apotome separated from slightly narrower clypeus (without seta SIII on the sclerite); anterior margin of frontal apotome straight; labrum present, remaining labral area variably fragmentary.
Antenna with 5 segments, diminishing in size distally Lauterborn organs about half as long as segment 3, opposite on apex of 2nd segment, with style. Ring organ in proximal 1/3 of segment 1, seta absent. Blade somewhat shorter than flagellum, accessory blade 1/3 length of segment 2.
SI plumose on both sides; SII simple; SIII short, slender; SIV normally developed. Seta praemandibularis simple. Labral lamellae normally pectinate. Pecten epipharyngis simple with numerous teeth of variable lengths, none on surface. Premandible with 2-3 teeth and beard.
Mandible with dorsal tooth; apical tooth followed by 3 inner teeth, many with inner row of 1-2 teeth. Pecten mandibularis modestly developed, lamellae simple. Seta subdentalis inserted on ventral surface, large, sickle-shaped. Seta interna inserted on dorsal surface, simple, 4-branched.
Mentum with trifid median tooth, of if simple with lateral crenations, 6 pairs of lateral teeth on each side, in a few species with up to 11 teeth. 1st and 2nd may be approximated, 4th lower than line of even decrease in size laterally in C. pictus group. Ventromental plates as wide as mentum, close medially, with smooth anterior margin; striae continuous. Setae submenti simple - long and slender or short and thick.
Lateral tubules absent, 2 pairs of ventral tubules in most species.
The species described by Townes (1945a) as Chironomus carus is hereby transferred to Goeldichironomus on the basis of individually reared larvae from Florida. Features of all 3 developmental stages place G. carus in the pictus group. Nilodorum devineyae, described from Florida, also belongs in Goeldichironomus. The larva of G. devineyae is very similar to that of G. holoprasinus except in having 2 pairs of short, simple ventral tubules and in lacking the fourth inner tooth of the mandible.
Goeldichironomus larvae possess a unique character amongst the Chironomini: a large, sickle-shaped seta subdentalis which is toothed along its inner margin. Two pairs of ventral tubules occur only in the larvae of Goeldichironomus and Chironomus. At low magnifications these two genera may be separated by the presence of labral sclerite 1 in Goeldichironomus.
Species groups of Goeldichironomus
- 1. Premandible with 3 teeth. Mentum with > 6 pairs of lateral teeth; 4th lateral tooth lower than neighbouring teeth ... pictus group
- -- Premandible bifid. Mentum with 6 pairs of lateral teeth; 4th lateral tooth taller than 5th ... 2
- 2. Anterior pair of ventral tubules forked or simple. Labral sclerite 3 disrupted into droplet-shaped flecks ... holoprasinus group
- -- Anterior pair of ventral tubules simple or absent. Labral sclerite 3 not divided ... natans group
Larvae of Goeldichironomus favour floating and drifting vegetation of small standing water bodies. Some species also occur in sediment.
The genus has its main occurrence in the tropics and subtropics of Central and South America. Goeldichironomus holoprasinus, G. carus, G. devineyae and G. amazonicus, are known from southern North America.