Cyphomella Sæther

Description

Introduction

Small to medium-sized larvae.

Dorsal Head

SIII seta arising from very obvious pits, backwardly directed, palmately divided.

Antenna

Antenna 5 segmented, weakly sclerotised beyond basal segment, basal segment subequal to flagellum, terminal segments very small. Blade arises on apex of segment 1, reaching apex of segment 2, 2nd blade (perhaps the displaced accessory blade) arises midway on segment 2. Lauterborn organs absent. Antennal seta absent. Style absent.

Labrum

SI seta slender, blade-like; SII similar to SI but twice as long, SIII very small, seta-like; SIVa moderate-lengthed, 3-segmented. Labral lamellae absent. Pecten epipharyngis broad divided into 3 triangular lobes. Premandible with 4 teeth, distal 2 longer than proximal, brush present.

Mandible

Mandible lacking dorsal tooth, with short apical tooth and 3 inner teeth. Seta subdentalis slender reaching subapical tooth. Seta interna with 4 branches, 1 plumose, 3 feathered on one side. Pecten mandibularis absent.

Mentum

Mentum with broad rounded or notched median tooth, flanked by 7 pairs of dark lateral teeth, median and first laterals paler than laterals. Ventromental plates 2-2.5 times as wide as high, finely striate, with crenulate anterior margin. Seti submenti simple.

Maxilla

Palp about as long as first antennal segment.

Body

Anterior parapods with long, very slender claws.

Notes

Taxonomic Notes

Only one larva is known (Sæther 1977b) which cannot however be associated with any of the named species. Characteristic features of this larva are the weakly sclerotized, 5 segmented antenna, small, scale-like pecten epipharyngis which is distally divided into 3 teeth, and the premandible which has 4 slender teeth of which the distal 2 are much longer than the basal pair.

Ecological Notes

Little information is available on Cyphomella. Most records are from large rivers. Known from the Nearctic, Palaearctic, Afrotropical and Australasian regions. Four named species are known from the Holarctic.

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