Beckidia Sæther

Description

Introduction

Moderate-sized larvae, to 5 mm long.

Dorsal Head

Not described.

Antenna

Antenna with 7 weakly sclerotised segments, basal segment as long as flagellum (AR c 1.0), or shorter. Ring organ not visible. Blade arising proximally on 3rd segment, extending beyond apex of antenna. Lauterborn organs lacking. Antennal blade as long or longer than flagellum. Antennal seta absent. Style strong, on segment 4.

Labrum

SI seta short, slender, simple, blade-like; SII elongate, broad blade, flanked by a long blade-like chaeta; SIII short, seta-like; SIVa 3 segmented, with SIVb a blade arising from base of SIVa. Labral lamellae weakly developed, divided into 2 parts. Pecten epipharyngis a single rounded scale. Premandible with 5 teeth, brush absent.

Mandible

Mandible lacking dorsal tooth, apical and 2 inner teeth brown. Seta subdentalis long, slender, extending to apical tooth. Seta interna absent. Pecten mandibularis absent.

Mentum

Mentum straight to weakly concave, with broad trifid, or at least notched, median, flanked by 4 pairs of lateral teeth, brown as median. Ventromental plates 1.5-2.0 times as wide as high, with coarse striae.

Maxilla

Palp elongate, as long as first 2 antennal segments combined.

Body

Posterior parapods long, tapering with a few apical claws. Procercus absent. Two pairs of anal tubules, dorsal pair about as long as parapods, ventral pair short.

Notes

Taxonomic Notes

Only Beckidia, Demicryptochironomus and Robackia amongst the Chironominae have 7 segmented antennae. Beckidia is distinguished from Demicryptochironomus by the form of the mentum and from Robackia by the long blade-like S 11 as opposed to the weak seta-like S 11 of the latter.

Ecological Notes

Larvae of Beckidia occur in sandy deposits of large rivers.

Holarctic and Afrotropical in distribution. Two species occur within the Holarctic: B. zabolotskyi is Palaearctic in its distribution, B. tethys is Holarctic. Only the latter is known as a larva.

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