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Paederinae Fleming 1821 |
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Fig. 1.18.1 Palaminus Erichson sp., abdomen. 1.18.2 Palaminus sp., anterovental view of forebody showing maxillary palpus. 1.18.3 Homaeotarsus bicolor (Gravenhorst), lateral view of thorax. 1.18.4 Lobrathium grande (LeConte), dorsal head with maxillary palpus. 1.18.5 Lathrobium Gravenhorst sp., dorsal view of thorax. 2.2.2 Staphylininae: Philonthus cognatus Stephens, dorsal view of head. 9.11.1 H. bicolor, from under stones in a dry streambed. 9.11.2 Paederus Fabricius sp. 9.11.3 Astenus discopunctatus (Say). 9.11.4 Achenomorphus corticinus (Gravenhorst), sifted from leaf litter. 9.11.5 Sunius confluentus (Say), from under bark. |
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The species of Paederinae in ECAS can be recognized by the following combination of characters: a well-sclerotized postcoxal process (Fig. 1.18.3), an apical maxillary palpomere that is 1/3 the length of the previous segment or shorter (Fig. 1.18.4), or distinctively flattened and broadened (Fig. 1.18.2), a well-defined neck (Fig. 2.2.2), and the pronotal base distant from the humeral angles of the elytra (Fig. 1.18.5). One paederine genus, Palaminus, does not key out with the rest because it lacks sutures on the abdominal tergites. However, the characteristically shaped apical maxillary palpomere (Fig. 1.18.2) and the fish scale-like sculpturing of the abdomen (Fig. 1.18.1) will distinguish it from all others. |
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Paederinae are widely distributed in North America in a variety of habitats, with a large number of species living at the margins of or near water. Two of the most conspicuous riparian genera are Homaeotarsus Hotchhuth (Fig. 9.11.1) and Paederus Fabricius (Fig. 9.11.2). Endosymbionts in the haemolymph of the latter genus produce the toxin pederin (Kellner 2001), with females of some species normally possessing up to ten times that of males (Kellner and Dettner 1995). Pederin can cause severe dermatitis if the beetle is crushed against the skin (Gelmetti and Grimalt 1993). Astenus Dejean is a distinctive genus normally found in wetlands and along shoreline habitat although some species prefer drier, open areas (Fig. 9.11.3). Occurring in a variety of litter and decaying organic matter, Achenomorphus corticinus Gravenhorst is a common species in southern Canada and eastern United States (Fig. 9.11.4); it is also attracted to lights. One of the most common staphylinids under bark in ECAS is Sunius confluentus (Say), a species sometimes brought indoors with recently cut firewood (Fig. 9.11.5). As far as known, all paederines are predaceous.
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