Zavreliella Kieffer

Description

Introduction

Small to medium-sized larvae, 4-7 mm long. Pale red larvae. Transportable case laterally flattened, narrowed at each end, opening circular.

Dorsal Head

Frontoclypeal apotome with slightly concave anterior margin, separate labrum present, remaining labral area fragmentary.

Antenna

Antenna with 6 segments segments 3 and 4 long. Lauterborn organs large, alternate on apex of 2nd, and on short pedestal subapically on 3rd segment, with long style. Ring organ near base of segment 1, seta present. Blade extending beyond flagellum, accessory blade very short.

Labrum

SI with bases fused, plumose on one side; SII lamelliform, plumose on one side only; SIII short, slender; SIV normally developed. Seta premandibularis simple, longer and thicker than in Lauterborniella. Labral lamellae undivided, relatively broad, short. Pecten epipharyngis tripartite, each plate with several finger-like teeth distally. Premandible with 3 distal teeth, 1 short, blunt inner tooth, with beard.

Mandible

Mandible with very strong dorsal tooth; apical tooth no stronger than 2 inner teeth, all teeth pale brown. Pecten mandibularis with apical lamellae stronger than basal, extending beyond apex of mandible. Seta subdentalis very long and broad, almost reaching tip of apical tooth, distal margin smooth. Seta interna inserted on dorsal surface, 4-branched.

Mentum

Mentum with all teeth brown with double, protruding median teeth, 6 pairs of lateral teeth on each side, 1st very small. 2nd high, remainder diminishing in size laterally. Ventromental plates 80% as wide as mentum, almost triangular in shape, very narrowly separated medially, with smooth anterior margin, striae restricted to basal and extreme lateral part. Setae submenti simple.

Body

Lateral tubules on segment X long, broad filamentous, extending beneath segment XI. Segment 11 dorsomedially with large, orally-directed hump. Procercus on conical tubercle, with short and some very long anal setae.

Notes

Taxonomic Notes

Amongst Holarctic Chironomini only Zavreliella and Lauterborniella larvae have transportable cases and a dorsal hump on segment l. Zavreliella has a circular opening to its case, long lateral tubules and a frontoclypeal apotome as well as simple seta subdentalis and setae submenti, which in Lauterborniella are respectively toothed and distally divided.

Three very similar Zavreliella species are known from the Holarctic, the status of which require verification.

Ecological Notes

Larvae of Zavreliella are mobile case-bearers amongst submerged vegetation in small bodies of standing water (Holarctic). Z. marmorata is widespread from the Holarctic, Afrotropical, Oriental and Australian regions. In central Europe it is obligately parthenogenetic but is bisexual in southern Europe and perhaps throughout the Nearctic. Neotropical species occur on drifting and floating vegetation but also in sediments in standing and flowing waters.

The genus is worldwide in distribution, with the greatest number of species in tropical South America. Three species occur in the Holarctic; 9 undescribed species have been found in the Neotropics. One species is known from the Afrotropical region, 3 from the Oriental region and 1 from Australia.

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