Paratanytarsus Thienemann & Bause

Description

Introduction

Small to medium-sized larvae, to 7 mm long.

Dorsal Head

Not described.

Antenna

Antenna with 5 segments on a tall pedestal lacking any basal tooth or spur. Antennal ratio > 1. Ring organ basal on 1st antennal segment. Seta weakly developed. Lauterborn organs modest, either sessile or on short stems, opposite on apex of elongate 2nd segment. 3rd segment shorter than 2nd. Antennal blade usually as long as 2nd segment, accessory blade short. Style on apex of 2nd segment, shorter than segment 3.

Labrum

SI seta comb-like, fused at bases, SII on large pedestal, distally plumose, perhaps sometimes simple, SIII short, simple, SIVa present. Labral lamellae well developed. Pecten epipharyngis 3-5 separate, finger-like lobes. Premandible bifid, brush strong; seta premandibularis simple.

Mandible

Mandible with brown dorsal tooth, apical tooth and 2-3 pointed inner teeth. Seta subdentalis long, curved, reaching to tip of apical tooth. Seta interna of 4 plumose branches. Pecten mandibularis well developed with many branched lamellae.

Mentum

Mentum with rounded or laterally notched median tooth, 5 pair of laterals, regularly decreasing in size or 2nd lateral much smaller than remainder. Ventromental plates close together medially, subequal in width to mentum, with moderately fine striae.

Body

Without tubules. Claws of posterior parapod simple, few.

Notes

Taxonomic Notes

Thienemann (1951a) divided what he called "Die Subsectio Paratanytarsus" into a number of genera and species groups on the basis of pupal morphology. Regrettably, there is still insufficient reared material available for a similar exercise to be performed for larvae. Although adapted to a wide range of ecological conditions, the larvae nevertheless form a well-defined, homogeneous group morphologically.

The most characteristic feature of this genus is the pecten epipharyngis which consists of 3-5 separate finger-like lobes. A similar form of pecten epipharyngis occurs in Lithotanytarsus and Sublettea. However Lithotanytarsus has characteristic conical projections mesally on the antennal pedestal and in Sublettea the Lauterborn organs are borne on pedicels which reach almost to the antennal apex, whereas in Paratanytarsus the Lauterborn organs are sessile or on very short pedicels.

Ecological Notes

Paratanytarsus is a eurytopic genus. It includes a parthenogenetic species (P. grimmi) which can be troublesome and persistent pests in water-supply systems.

The distribution of the genus is probably worldwide, with many species; 20 are listed from Europe along (Reiss and Sawedal, 1981a), most of which are inadequately described as larvae.

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