Family HYDROBIOSIDAE

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Family HYDROBIOSIDAE

Compiler and date details

Arturs Neboiss, Department of Entomology, National Museum of Victoria, Abbotsford, Victoria; updated (2002) by Alice Wells, Australian Biological Resources Study, Canberra, Australia

Introduction

Medium sized caddis-flies (wing span 10–30 mm), with dark brown to black, often mottled wings.

The family occurs predominantly in the Australian and Neotropical Regions, although a few species are found in the Oriental, Nearctic and Palaearctic Regions. Schmid (1989) discussed the the group in detail, considering it to be a 'primitive family of Gondwanian origin', and probably polyphyletic.

Originally, this group was regarded as a subfamily within the Rhyacophilidae. There are two subfamilies: Apsilochoreminae and Hydrobiosinae; they include 48 genera, placed by Schmid (1989) in 19 groups, and approximately 298 species. Both subfamilies, 15 genera and 67 species, are known from Australia. In recent works, Schmid (1989) decribed eight new species; Dean & Bunn (1989) described the larvae of south-western Australian species, giving notes on their biology; and Dean (1991) provided preliminary keys for identification of late instar larvae. Neboiss (2003) described three further species from Tasmania.

Diagnosis

Adult: ocelli present. Maxillary palpi 5-segmented in both sexes, with segments 1 and 2 cylindrical, shorter than others, terminal segment simple; antennae as long as or slightly shorter than forewing. Mesoscutum and scutellum without setal warts. Wings elongate, oval, venation complete, often differing in sexes; forewings with hyaline line along M and hyaline areas around cross-veins r-m, m-cu and at arculus; vestiture in some genera evenly pubescent, in others with tufts of thickened upright hairs on veins; males often with small areas of modified setae on ventral surface of hindwing; discoidal cell is closed or open in forewing, open in hindwing.

Tibial spurs 1: 4: 4 or 2: 4: 4.

Larva: body smooth with few scattered bristle-like hairs; colour variable from pale creamy white to greenish; only head and pronotum sclerotized. The free-living larvae of Hydrobiosidae are prognathous. They inhabit mainly cool, fast flowing mountain streams, few are adapted to slow flowing waters, some even tolerate stagnant pools. They are predatory, mainly on other aquatic insects. The larva constructs a crude pupal chamber of small stones; the pupa is enclosed within an amber coloured silken cocoon.