Family HALIPLIDAE

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Family HALIPLIDAE

Compiler and date details

2002 - Updated by Andrew A. Calder, CSIRO Entomology, Canberra, Australia

1987 - J.F. Lawrence, T.A. Weir & J.E. Pyke

Introduction

This family includes five genera and about 200 species worldwide, but only 14 species in the genus Haliplus are known to occur in Australia. Haliplids appear to represent an early adephagan offfshoot and are usually placed near Dytiscidae in classifications. Beutel & Roughly (1988) maintain this position although they postulate an independent invasion of the aquatic habitat. Although true haliplids are not represented among the fossils of the Mesozoic, an apparently related group, the Triaplidae, occurs in Upper Triassic beds of Central Asia (Arnoldi et al. 1977). A number of primitive and unique features of the family suggests that it is an independent aquatic lineage representing an early offshoot from the ancestral Adephaga (Bell 1966; Lawrence & Newton 1982).

Haliplids occur among aquatic vegetation at the edges of ponds, lakes and slow-moving streams. Adults usually crawl along the bottom or swim rather poorly, using the middle and hind legs, the tarsi of which are provided with swimming hairs. They may also walk on land and are capable of flying, sometimes being attracted to lights at night. They obtain air from the surface and store it in both the subelytral cavity and the space beneath the large metacoxal plates. This enables them to spend considerable periods under water, where they may overwinter. Eggs are attached to host plants or embedded in the plant tissue. Larvae obtain air through the cuticle, aided by long, tracheated filaments or microtracheal gills (Seeger 1971). Functional spiracles are absent, except in the third instar which leaves the water to pupate in damp soil at the water's edge. Haliplids are algophagous in both adult and larval stages, although some have been reported feeding on insect larvae. Various Northern Hemisphere species are known to feed on filamentous algae such as Spirogyra or stoneworts such as Chara and Nitella. Larvae are capable of sucking algal cells or tissue through perforations in the mandibles. Adaptive modifications of the front legs and mandibles in larvae feeding on filamentous algae differ from those in stonewort-feeders. (Hickman 1930, 1931; Leech & Chandler 1956; Seeger 1971; Spangler 1991).

Larval Haliplidae are described and illustrated in Bertrand (1972), Leech & Chandler (1956) and Spangler (1991). The last world catalogue for the family is that of Zimmerman (1920). The Australian species were first revised by Watts (1988) of the South Australian Museum, Adelaide and subsequently by Vondel (1995) for the Australasian Region and the Moluccas. Worldwide, six subgenera are recognised for the genus Haliplus Latreille (Vondel 1995). The Australian species of Haliplus belong to three of these subgenera: Liaphlus Guignot (alastairi, australis, ferruginipes, signatipennis, sindus, stepheni, testudo, timmsi, wattsi), Neohaliplus Netolitzky (bistriatus, fuscatus, gibbus, hydei) and Phalilus Guignot (oberthuri, storeyi).