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HEMIPTERA, Gelastocoridae -- <Images> & <Juveniles>

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The Gelastocoridae or toad bugs contain about 105 species. They resemble toads by their warty appearance and movements. These riparian insects occur at the margins of streams and ponds, where they are predators of other insects. The family has a worldwide distribution, with most species occurring in the tropics.

The following discussion is derived primarily from Cassis et al. (2002):

Toad bugs average 6.1–11 mm long and have an ovoid body with roughened surface, frequently with a warty appearance. The eyes are large, and protruding with ocelli usually being present. The short antennae have four segments. The labium is 4-segmented and does not extend beyond the forecoxae. The pronotum is large, transverse and wider than the head. The scutellum is triangular and large. The metathoracic scent glands are well developed in the Gelastocorinae, and absent in the Nerthrinae. The larvae lack dorsal abdominal gland openings. The forewings are mostly divided into clavus, corium and membrane. Menke (1979) reported wing polymorphism as common, with flight rare, particularly in Nerthra Say species. In some species the hemelytra are fused along the midline (Todd 1960). Parsons (1960) records a reduction in hind wings and wing musculature in Gelastocoris Kirkaldy. The mid and hind legs are slenderand the forefemora are incrassate. The foretarsi are diagnostic at the subfamily level, the Gelastocorinae having a fully articulated, 1-segmented tarsus, with the foretarsus and tibiae fused and a single claw on the pretarsus. The pretarsi of the forelegs are asymmetrical, with the inner claw reduced. The hind tarsus is 3-segmented. The abdominal sternites are asymmetrical, particularly in the males. The male genitalia are asymmetrical with the left paramere reduced or absent. The females lack a laciniated ovipositor (Parsons 1959, 1960; Slater 1982).

Gelastocoris species are found on the muddy banks of streams, ponds, lakes, swamps and roadside ditches. Hungerford (1922) gave an account of the biology of the North American species, Gelastocoris oculatus (Fabricius). Nerthra species are found in a wide variety of habitats, including semiaquatic habitats, but are sometimes found far from water. Todd (1955) reported Nerthra species from leaf litter, under debris, in soil, and sometimes in decomposing plant material, or cow dung. He reported the Neotropical species, Nerthra nepaeformis (Fabricius), from banana plantations. Burrowing has been given as a common behaviour of toad bugs, in both wet and dry conditions (Bennett & Cook 1981). Both larvae and adults of the widespread species Nerthra macrothorax (Montrouzier) are found in and under decaying vegetation of Pandanus Parkinson and Erythrina indica Lam. (Todd 1960). The habitats of other Australian species are poorly known. Carver et al. (1991) report that most Australian species are found near water; a few species are collected away from water, particularly in rainforest habitats, and N. plauta Todd is found in association with spinifex. Toad bugs are considered to be opportunistic predators and scavengers (Bennett & Cook 1981). Hungerford (1922) recorded them feeding on a variety of arthropods including leafhoppers, various flies and a locust species.

Todd (1955) discussed the phylogeny of the gelastocorids and suggested a relationship with the Naucoridae. He proposed that toad bugs represent an intermediate taxon between terrestrial and truly aquatic bugs. Popov (1971) and Rieger (1976) provided phylogenetic schemes for the Nepomorpha and indicated a sister-group relationship between the Ochteridae and Gelastocoridae. Rieger (1976) indicated that the Ochteroidea are a plesiomorphic group in the Nepomorpha, with the Nepoidea being the only group which is more basal.

Stys & Jansson's (1988) classification of the Gelastocoridae recognised two subfamilies (Gelastocorinae and Nerthrinae), and three genera (Gelastocoris, Montandonius Melin and Nerthra). Todd (1955) revised the Gelastocoridae of the world, and described and keyed all the taxa, including many new species. Todd (1959) revised the Gelastocoridae of Melanesia, and recognised 23 Melanesian Nerthra species in two major species groups. Todd (1961) provided a

Checklist of the Gelastocoridae.

In Australia there are 21 Nerthra species. Todd (1960) revised the this fauna and recognised four species groups. Many are widely distributed in eastern Australian, a few are endemic to Western Australia, and one species is endemic to Tasmania. The elongata and alaticollis species groups are endemic to Australia. The laticollis species group also occurs in Melanesia and the rugosa-group is also found in the Oriental and Afrotropical regions, and in the Western Hemisphere. Only one species, N. macrothorax, is also found outside Australia (Cassis et al., 2002).

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References: Please refer to <biology.ref.htm>, [Additional references may be found at: MELVYL Library]

Bennett, D.V. & Cook, E.F. 1981. The semiaquatic Hemiptera of Minnesota (Hemiptera: Heteroptera). Technical Bulletin. Agricultural Experiment Station, University of Minnesota 332: 1-59

Carver, M., Gross, G.F. & Woodward, T.E. 1991. Hemiptera (bugs, leafhoppers, cicadas, aphids, scale insects, etc.) [with contributions by

Cassis, G., Evans, J.W., Fletcher, M.J., Hill, L., Lansbury, I., Malipatil, M.B., Monteith, G.B., Moulds, M.S., Polhemus, J.T., Slater, J.A., Štys, P., Taylor, K.L., Weir, T.A. & Williams, D.J.]. 2002. pp. 429-509 in CSIRO (ed.). The Insects of Australia. A textbook for

students and research workers. Melbourne : Melbourne University Press Vol. 1 xiii 542 pp.

Family Gelastocoridae in Australian Faunal Directory. Australian Government, Department of the Environment, Water, Heritage and the Arts. URL consultato il 04-03-2009.

Hungerford, H.B. 1922. The life history of the toad bug. University of Kansas Science Bulletin 24: 145-171

Menke, A.S. 1979. Family Gelastocoridae. pp. 126-130 in Menke, A.S. (ed.). The Semiaquatic and Aquatic Hemiptera of California (Heteroptera: Hemiptera). Berkeley : University of California Press

Moreira da Costa Lima, A. 1938. XXII. Ordem Hemiptera in Insetos do Brasil. Tomo 2°, (in (PT)) Escola Nacional de Agronomia, pp. 312-314

Parsons, M.C. 1959. Skeleton and musculature of the head of Gelastocoris oculatus (Fabricius). Bulletin of the Museum of Comparative Zoology, Harvard 122: 1-53

Parsons, M.C. 1960. Skeleton and musculature of the thorax of Gelastocoris oculatus (Fabricius). Bulletin of the Museum of Comparative Zoology, Harvard 122: 299-357

Popov, Y.A. 1971. [Historical development of the hemipterous infraorder Nepomorpha.]. Trudy Paleontologicheskogo Instituta. Akademiya Nauk SSSR 129: 1-228 [In Russian]

Rieger, C. 1976. Skelett und Muskulatur des Kopfes und Prothorax von Ochterus marginatus Latreille. Beitrag zur Klärung der phylogenetischen der Ochteridae (Insecta, Heteroptera). Zoomorphology (Berlin) 83: 109-191

Slater, J.A. 1982. Hemiptera. pp. 417-447 in Parker, S.P. (ed.). Synopsis and Classification of Living Organisms. New York : McGraw Hill Book Co

Štys, P. & Jansson, A. 1988. Check-list of recent family-group and genus-group names of Nepomorpha (Heteroptera) of the world. Acta Entomologica Fennica 50: 1-44

Todd, E.L. 1955. A taxonomic revision of the family Gelastocoridae (Hemiptera). Kansas University Science Bulletin 37: 277-475

Todd, E.L. 1959. The Gelastocoridae of Melanesia (Hemiptera). Results of the Archbold Expeditions. Nova Guinea ns 10: 61-94

Todd, E.L. 1960. The Gelastocoridae of Australia (Hemiptera). Pacific Insects 2: 171-194

Todd, E.L. 1961. A checklist of the Gelastocoridae (Hemiptera). Proceedings of the Hawaiian Entomological Society 17: 461-476