Shangomyia Sæther & Wang

Description

Introduction

Large, pale red of uncertain length.

Dorsal Head

With SIII on sclerotized anterior margin of frontoclypeal apotome, deeply divided by apparently flexible area from separate anterior sclerites.

Antenna

Antenna 5-segmented, with 3 short apical segments, 3rd subequal to 5th, both shorter than 4th; basal segment with basal Ring organ, strong seta arising from mid-segment; style slightly longer than Lauterborn organs, which are subequal to length of 3rd segment; blade extending far beyond antennal apex

Labrum

Labrum narrowed and tapering anteriorly. SI simple, stout, SII and SIII simple, long and thin, SIVa, b quite well developed. No evidence of labral lamellae. Pecten epipharyngis of 3 broad rounded scales, 3 chaetulae laterales, weakly serrate apically. Premandible with one apical tooth and fine, stubble brush.

Mandible

Mandible without dorsal tooth, with apical tooth and four inner teeth, decreasing in size from outer to inner, with 4th (innermost) larger, bulging from swollen mola with narrow seta subdentalis curving around its margin; mola bearing 4 strong spines; seta interna absent.

Mentum

Mentum with prominent extended saggitate median tooth, with four pairs of retracted lateral teeth, with outermost teeth fused basally, separated by notch, ventromental plate small and short, without beard, with bifid seta submentum.

Body

Body setae short. Procercus strong, darkened, 4-6 times as long as wide, with 2 strong lateral setae and 6 relatively short apical setae. Anterior parapods apparently scarcely separated, crowned with simple yellow claws. Posterior parapods claws large curved, simple, dark yellow. Anal papillae undeterminable.

Notes

Taxonomic Notes

Shangomyia is distinctive amongst Chironomini by the shape of the mentum. The reduced ventromental plates are shared by Harrisius and Stenochironomus: in this they resemble Orthocladiinae, where they are also keyed.

Ecological Notes

Only one complete larva of Shangomyia has been collected, from a fast-flowing, essentially pristine river in northern Borneo (Temburong, Brunei) exposed by fragmenting immersed wood from a major log jam. The wood quality was unrecorded since many pieces of variable decomposition were harvested and assessed for mining taxa; however, the larva was distinctively red coloured and active when its tunnel was exposed. The gut contents comprises fragmented wood fibres typical of wood mining chironomids examined from elsewhere.

A larval exuviae was collected from drift in the same river, and a third larva also was collected as an exuviae, associated with (attached to) a drifting pupa, from the Kelian River in Kalimantan (Indonesian Borneo), at a site where both mine and human disturbance were evident, but downstream of a semi-pristine section. All other evidence pertaining to habitat preference comes from interception of drifting pupal exuviae, from a wide geographical range of running waters from south India to Thailand. Thai sites appear representative of the wider range: flowing waters in unregulated rivers, with riffles and pools, naturally wooded riparian zones, and flowing, sometimes at elevations up to 1,000m asl, with temperature regimes less than extremes of air temperature. Water temperatures in Sungai Belalong in August 1995 varied little from 25°C, with air temperatures ranging from 23 to 31°C.

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