Kribiodorum Kieffer

Description

Introduction

Medium-sized, red, up to 6 mm long. Head slender and rectangular, with mandibles set far forwards.

Dorsal Head

Frontal apotome without frontal pit, with weakly concave anterior margin, posteriorly drawn out into narrow point; clypeus and labrum appearing fused - SII on clypeo-labral apotome, SIII lying anterior to suture; lateral labral sclerites fragmentary.

Antenna

Antenna with 5 segments. Lauterborn organs minute, opposite, style apical on segment 2, almost as long as segment 3. Ring organ large in basal half of segment 1, seta absent. Blade extending to near or beyond apex of antenna, accessory blade short.

Labrum

SI and SII plumose apically; SIII short, slender, and simple; SIV a strikingly large. Seta premandibularis simple. Labral lamellae in one piece. Pecten epipharyngis of three distally toothed plates. Premandible with 3 teeth and strong brush.

Mandible

Brown, inner teeth blackish-brown; dorsal tooth absent, well developed, long apical tooth and 4 distally-flattened, inner teeth. Pecten mandibularis absent. Seta subdentalis inserted on ventral surface, simple, slender, long, extending to outermost of inner mandibular teeth. Seta interna absent.

Mentum

Mentum with deeply sunken, simple median tooth, and 6 pairs of convexly arranged lateral teeth such that mentum appears biconvex. Ventromental plates separated medially by 2x breadth of median mental teeth, strongly curved posteriorly, and only little wider than mentum; strongly striated medially and beneath oral margin, with spinules increasing in size laterally. Setae submenti unusually long, extending well beyond mentum, simple.

Body

Lateral and ventral tubules absent. Claws of anterior and posterior parapods partially serrated. Posterior parapods, basal to claws, with circle of minute spinules.

Notes

Taxonomic Notes

Kribiodorum larvae can be recognized by their slender, rectangular head and by the fact that the mandibles are set very far forward. The mentum is biconvex with a deeply recessed, simple median tooth. The setae submenti are very long and extend well beyond the mentum, a character which otherwise amongst Holarctic Chironomini occurs only in Fissimentum.

The North American species K. perpulchra (Mitchell), was placed previously in Lauterborniella, and then in Stelechomyia Reiss, an objective junior synonym of Kribiodorum.

Ecological Notes

The type of the genus, K. pulchra, was described from adults alone, from Kribi in Cameroon, but the immature stages remain unknown. The known larvae of Kribiodorum [K. perpulchra (Mitchell)] live on or in dead wood in flowing water in southern and eastern North America. A third species is known from pupae and adults from south-east Asia.

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