Major Group: Insecta Order: Hemiptera Family: Gelastocoridae Genus: Nerthra This family is represented in Australia by a single genus, Nerthra Say. |
Descriptive Features: antennae 4-segmented, short, not visible from above
eyes large, protruding and reniform
ocelli usually present
head subtriangular and somewhat depressed
rostrum 4-segmented, short, does not extend beyond forecoxae
pronotum large, transverse, wider than the head
scutellum triangular, large
ovoid body with a dull, roughened surface, often with a warty appearance
wing polymorphism common, with flight rare
in some species the hemelytra are fused along the midline
mid- and hindlegs slender, forefemora incrassate
fore tarsus cylindrical, with 1 or more segments
hind tarsi 3-segmented
Total length: 5.1 - 10.8mm |
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Nerthra sp. |
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Taxonomic Checklist: Species Nerthra adspersa Stal Nerthra alaticollis Stal Nerthra annulipes Horvath Nerthra appha Cassis & Silveira Nerthra elongata Montandon Nerthra falcatus Cassis & Silveira Nerthra femoralis Montandon Nerthra grandis Montandon Nerthra hirsuta Todd Nerthra hylaea Todd Nerthra luteovaria Distant Nerthra macrothorax Montrouzier Nerthra nudata Todd Nerthra monteithi Cassis & Silveira Nerthra plauta Todd Nerthra polhemi Cassis & Silveira Nerthra probolostyla Todd Nerthra sinuosa Todd Nerthra stali Montandon Nerthra suberosa Erichson Nerthra soliquetra Todd Nerthra tasmaniensis Todd Nerthra tuberculata Montandon Nerthra walkeri Todd |
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Distribution: Australia wide
Sensitivity Rating: SIGNAL grade 5
Functional Feeding Group: predators |
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Mitta Mitta River, Eskdale Vic |
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Ecology: Instream habitat: Commonly known as ‘toad bugs’ Gelastocoridae species occur on the ground and in the leaf litter in a variety of habitats, from both wet and dry sclerophyll forests to open heathland habitats. They are considers to be semi-aquatic species occurring in riparian and littoral areas of lentic water bodies or from very slow flowing areas of rivers. They are found under stones and plant debris or burrowing into wet sand or mud. Feeding ecology:Toad bugs are opportunistic predators and scavengers feeding on a variety of small aquatic and semi-aquatic insects. The roughened and mottled nature of the body provides a good camouflage (cryptozoic). Gelastocorid bugs manage a staggered run to seize prey, killing it with their needle-like mouthparts. Habit: Very little is known about the biology of Australian Nerthra species. Northern Hemisphere species seem to be nocturnal, hiding and resting during the day then crawling across wet or damp substrata at night to forage and hunt. Australian Gelastocoridae species are usually flightless with the wings either absent or greatly reduced. Life history: The life cycle is poorly known. Eggs are broadly oval, flattened on one side and the shell has a rough hexagonal sculpture. Some Northern Hemisphere species deposit eggs in small holes in mud under stones near the water. The female guards the eggs until they hatch. Males stridulate by rubbing the sclerotized posterior margin of the proctiger on a roughened area on the genital capsule. |
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Information Sources: Andersen & Weir 2004, Cassis & Gross 1995, Lansbury & Lake 2002, Todd 1960, Gooderham & Tsyrlin 2002, Cassis & Silveira 2001 Key to species: Andersen & Weir 2004 |
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