Family MESOVELIIDAE

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Family MESOVELIIDAE

Compiler and date details

October 2010 - Dr G. Cassis, University of New South Wales, Sydney, NSW

Introduction

The gerromorphan family Mesoveliidae is a cosmopolitan group of semiaquatic bugs. They are commonly called water-treaders or pondweed bugs. The family contains 12 genera and 46 species (Andersen & Polhemus 1980; Slater 1982; Polhemus & Polhemus 1989; Zoological Record 1980–1994; Andersen & Weir 2004a; Henry 2009; Polhemus, J.T., pers. comm.).

Mesoveliids are mostly greenish to brown, long-legged bugs, with an elongate-ovoid body. They are small, ranging in length from 1.2 to 4.5 mm. The head is large and elongate, projecting well beyond the eyes. Ocelli are present, except in apterous adults. The antennae are 4-segmented. The labium is 3-segmented, with the maxillae strongly serrated. The winged morphs have an exposed, enlarged, bipartite scutellum (undeveloped in apterous species and morphs). The adults have an omphalium metathoracic scent gland. The tarsi are 3-segmented with the first segment very small and the claws apical. Wing polymorphism is common. The forewings are homogeneous with the clavus and membrane of similar texture, the latter lacking veins. The corium has two to three closed cells. The ovipositor is well-developed, serrate and laciniate. The larvae have reduced dorsal scent glands on terga III and IV (Andersen & Polhemus 1980; Andersen 1982; Slater 1982; Dolling 1991).

The Mesoveliidae are found mostly in lentic waters, commonly associated with the edges of water bodies, and floating debris and plants. Carver et al. (1991) reported that Australian Mesovelia Mulsant & Rey species are associated with freshwater and brackish estuarine waters. Smith (1988) stated that a few mesoveliid species live on water-soaked moss or seeping rock faces. Gagné & Howarth (1975) described cavernicolous mesoveliids, which are found on moist slime fungi on the walls of lava tubes. Yuasa (1929) reported mesoveliids from the moist walls of coastal caves. Slater (1982) reported that plesiomorphic mesoveliids are found away from water bodies. The Australasian species Austrovelia queenslandica Malipatil & Monteith and Phrynovelia papua Malipatil & Monteith are secondarily terrestrial, and are found in leaf litter. Andersen (1982) concluded that the ancestral habitats of mesoveliids were either moist litter or soil, moss or seeping rock faces.

Mesoveliids are predators and scavengers, feeding on other arthropods, including ostracods (Hungerford 1917), and mosquito larvae and pupae (Brooks & Kelton 1967). Polhemus & Chapman (1979) report that North American species feed on dead or disabled insects on the water surface or on floating vegetation. Hoffmann (1932) gave a detailed account of the life histories of North American Mesovelia species. Ekblom (1928) reviewed the biology of European mesoveliid species. Southwood & Leston (1959) and Dolling (1991) reported that mesoveliids oviposit in aquatic plants. Cobben (1968) described the egg structure, embryology and eclosion of mesoveliids.

Reuter (1912) placed the Mesoveliidae close to the Nabidae and Reuviidae. Sahlberg (1920) included the mesoveliids within the Gerromorpha on the basis of labial and pretarsal structure. Scudder (1959) proposed a novel arrangement of the mesoveliids with the Saldidae because of similarities of the female genitalia. Cobben (1968, 1978) and Andersen (1982) provided the most conclusive evidence for the inclusion of the Mesoveliidae within the Gerromorpha. Andersen & Polhemus (1980) reviewed the world fauna, and included a generic key and descriptions, and a checklist of species. They recognised two subfamilies: the cosmopolitan Mesoveliinae (seven genera) and the Madeoveliinae (two genera from the Neotropical and Afrotropical regions). Other works of importance include Horváth's taxonomic revision of the family (Horváth 1915) and world catalogue (Horváth 1929). Jaczewski (1930) gave a key to the American species and Drake (1949) provided a checklist of the Western Hemisphere species. Froeschner (1981) gave an account of the mesoveliids of Ecuador. Bennett & Cook (1981) reviewed the mesoveliids of Minnesota, including a summary of their biology and morphology. Smith (1988) catalogued the North American and included three Mesovelia species. Spangler (1990) described a new Mesovelia species from Belize and gave a checklist of the New World species. Polhemus & Polhemus (2000) revised the genus Mesovelia with the descripton of two new species and new synonymy.

The Australian mesoveliid fauna comprises six Mesovelia species and one Austrovelia Malipatil & Monteith species. The most commonly encountered Mesovelia species, M. vittigera Horváth, is known from northern Australia, and is also widely distributed in the Eastern Hemisphere (Horváth 1915; Polhemus 1993). The Mesovelia species from Norfolk Island, often identified as M. hackeri Drake in museum collections, is an undescribed species (Polhemus, J.T., pers. comm.). Andersen & Polhemus (1993) listed three Australian mesoveliid species in their world checklist. Inclusion of Mesovelia horvathi Lundblad in the Catalogue is a new Australian record and is based on identifications of specimens from Queensland and the Northern Territory. Malipatil & Monteith (1983) described Austrovelia queenslandica from northern Queensland. Andersen & Weir (2004a) revised the Australian Mesoveliidae as well as a phylogenetic analysis of the infraorder Gerromorpha. They also published a key and biological notes to all Australian water bugs, including mesoveliids (Andersen & Weir 2004b).