Oliveridia Sæther

Description

Introduction

Medium-sized larvae.

Antenna

Antenna with 6 segments; segments consecutively smaller; segment 6 vestigial. Ring organ in basal 1/4 of segment 1. Blade shorter than flagellum. Lauterborn organs distinct.

Labrum

Labrum with SI finely plumose. Labral lamella simple, triangular. Chaeta media broad, serrate. Pecten epipharyngis consisting of 3 simple, sclerotized, smooth spines. 8 pairs of chaetulae laterales present; 2-3 shorter and strongly serrated. Premandible with 2 apical and 1 distinct accessory teeth; brush absent.

Mandible

Apical tooth much shorter than combined width of 3 inner teeth. Seta subdentalis thin and long. Seta interna with 5-6 smooth branches.

Mentum

Mentum with 1 median and 6 pairs of lateral teeth; 3-7 central teeth slightly paler than most other teeth. Ventromental plate prominent; beard absent.

Maxilla

Maxilla with anterior lacinial chaeta longitudinally curled, forming about half a cylinder. At most one lamella of galea serrated. Pecten galearis well developed.

Body

Body with well developed procercus, sclerotized caudally; with 6-7 anal setae. Anal tubules shorter than posterior parapods, tapered to point. Body setae inconspicuous.

Notes

Ecological Notes

The first described species, doubtfully distinct from Hydrobaenus, is a typical unltraoligotrophic lake dweller, known from Canadian Arctic islands, Greenland, Spitzbergen and Iceland. Another species is known from a river in Kansas, a quite different habitat to the previous reports.

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