Major Group: Insecta Order: Coleoptera Family: Georissidae (formerly within Hydrophilidae) Genus: This family is represented by a single genus worldwide, Georissus. |
Descriptive Features: Adults
antennae 7- to 9-segmented with 3- or 4-segmented club
2nd segment of maxillary palpi slender
body broad, compact, round, black
abdomen with more than 3 ventrites
ventrite 1 divided into 2 or 3 parts by hind coxae
elytra highly sculptured, exposing less than 2 complete abdominal tergites
prothorax with pair of notopleural sutures separating notum from externally visible pleuron on each side
tarsi 5-segmented
basal segment of hind tarsi shorter than 2nd
size: <2mm Larvae
labrum completely fused to head capsule
legs 3-segmented
abdominal tergum 8 usually subterminal, not forming spiracular siphon or spiracular chamber
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Georissus adult |
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Taxonomic Checklist: Species Georissus australis King Georissus kingi Blackburn Georissus occidentalis Carter
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Distribution: N Aus, SW Aus, Vic
Sensitivity Rating: none; formerly within Hydrophilidae - SIGNAL grade 2
Functional Feeding Group: shredders (adults), predators (larvae) |
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Mitta Mitta River at Eskdale, Vic |
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Ecology: Little is known about Australian species, all of the ecological information below is from the Northern Hemisphere. Instream habitat: Georissidae is one of a group of beetle families commonly known as ‘shore beetles’. Adults and larvae are generally viewed as terrestrial beetles that are found almost exclusively very close to the edges of pools or rivers where they occur in moist mud or fine sand, especially in places with little vegetation. Feeding ecology: Adults feed on plant material and decaying organic matter. Larvae are predators. Habit: Life history: Eggs are enclosed within a densely woven silk cocoon.There are two larval instars.
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Information Sources: Watts 2002, Hansen 2000, Jach 1998, Bernhard et al. 2006, Calder 2004, Williams 1980 Key to Species: none |
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