Botryocladius Cranston & Edward

Description

Introduction

Medium-sized larvae, to 6 mm long.

Dorsal Head

Dorsal surface of head single sclerite.

Antenna

Antenna either 5 or 6-segmented, with 6th, when present, very fine filament, segment 3 subequal to or more usually shorter than segment 4. Antennal Ratio 0.72-1.7. Ring organ near base of segment 1; antennal blade simple, extending to apex of segment 3, in one species to apex of 5th; Lauterborn organs varying from distinct and subequal in length to antennal segment 3, to somewhat weaker; style very short, perhaps sometimes absent.

Labrum

Labrum with SI bifid, SII-IV simple, SII thickened and retracted posteriorly to lie external to fine SIII, with SIVa externally on similar alignment; one chaeta serrate, remainder simple; spinulae strong. Premandible with one or 2 apical teeth and moderately developed premandibular brush. Pecten epipharyngis of 3 separate scales. Ungula short and squat with few short and simple or pectinate chaetae. Basal sclerite spatulate

Mandible

Mandible with outer and inner margins smooth. Length of apical tooth either shorter than 1st inner tooth and displaced onto different plane, subequal to combined width of 4 inner teeth, or on same plane and slightly shorter than combined width of 3 inner teeth. Seta subdentalis present, more or less rounded. Seta interna with 5-7 simple branches.

Mentum

Mentum with median tooth either apparently simple and broad, or weakly to strongly paired with variably developed nipple on each median tooth; 5 pairs of lateral teeth either decreasing on even slope, or with outermost tooth more aligned with its inner neighbour. Ventromental plate narrow or may extend to outermost mental tooth (extent depends on degree of compression); beard of sparse to strong setae which may be quite broad and apically bifurcate.

Maxilla

Palp squat, bearing few simple setae.

Body

Body without any evidence of lateral setae. Anterior parapods separate, with crown of elongate, simple, pale spines and yellow, pectinate claws, merging into more basal area of fine, pale, straight spines almost linking 2 parapods at base. Posterior parapods separate, with apical group of simple claws. Procercus as wide as high, sometimes partly pigmented, bearing 2 very proximate median setae and 4 medium-length anal setae. Two pairs of elongate-globular anal tubules.

Notes

Ecological Notes

Larval Botryocladius occur in a range of mostly temperate habitats, ranging from glacial-fed lakes (Patagonia), to moderate elevation lakes (Patagonia, Tasmania, s.e. Australia), to rivers and creeks (Patagonia and s.e. Australia) to ephemeral streams (southern and western Australia) (Cranston and Edward, 1999).

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