Echinocladius Cranston

Description

Introduction

Medium-sized larvae, to 6 mm long.

Dorsal Head

Dorsal surface of head with single frontoclypeal sclerite, partially fragmentary posteriorly, smooth anteriorly.

Antenna

Antenna 6-segmented, with 3rd subequal to 2nd, 4th and 5th short, 6th minute. AR c. 1. Ring organ at base of segment 1; antennal blade simple, extending to sub-apex. Lauterborn organs well developed, dilate, subequal in length to segment 3, style half length of 3rd segment.

Labrum

Labrum with SI simple, broadly lanceolate, SII long, slender, SIII and IVa,b simple and short, one chaeta lanceolate, remainder simple; spinulae strong. Premandible with one apical and one small but broad inner tooth, with weak premandibular brush. Pecten epipharyngis of 3 unfused rounded scales, the median one apparently either serrate, or notched, or both. Ungula short and squat with few short and simple and pectinate chaetae.

Mandible

Mandible with outer and inner margins smooth, apical tooth shorter than combined width of 4 inner teeth. Seta subdentalis present, more or less rounded. Seta interna with 2 simple branches.

Mentum

Mentum with median tooth simple and broad with median nipple; 5 pairs of lateral teeth decreasing on even slope. Ventromental plate narrow, basally overlying bulbous to ledge-shaped projection ventral to outermost mental teeth and extending nearly to outermost mental tooth (extent depends on degree of compression); beard absent.

Maxilla

Palp with squat palpiger, few galear lamellae, without pecten galearis, with one large triangular lacinial chaeta.

Body

Body with no evidence of lateral setae. Anterior parapods separate, with crown of elongate, simple, spines and small pectinate claws. Posterior parapods separate, with apical group of simple claws. Procercus as wide as high, dark pigmented posteriorly bearing 3 (perhaps 4) shortish anal setae. Anal tubules scarcely developed.

Notes

Ecological Notes

The sole species, Echinocladius martini is quite abundant in eastern Australian flowing waters, predominantly where shaded from elevated temperatures, from north Queensland, to s.e. Australia and Tasmania, especially at middle to high elevations. In s.e. Australian subalpine streams larval E. martini (as "MO5") were amongst the most abundant chironomids living as gatherers on immersed wood in streams with riparian native vegetation, with abundances little reduced in streams with riparian pine plantation, but almost absent from otherwise comparable unshaded grassland streams (McKie and Cranston, 1998). In the Australian tropics, E. martini larvae are abundant at the water/surface interface, where they form translucent silken tubes, which are also used for pupation (B. McKie pers. comm.). As with several other cool stenothermic Orthocladiinae, this predominantly lotic species occurs in standing waters at high elevations in Tasmania, where lower temperatures and aerating effects of wave action probably ensure favourable conditions.

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