Talarico Federica, Brandmayr Pietro, Giglio Anita, Massolo Alessandro, Brandmayr Tullia Zetto
Department of Ecology, University of Calabria, I-87036.
Zookeys. 2011(100):203-14. doi: 10.3897/zookeys.100.1528. Epub 2011 May 20.
In carabid beetles, physiological and behavioural characteristics reflect specific habitat demands and there is a strong correlation between body form and habit in species with different life style. In this study, we compared the morphometry and compound eye characteristics of three species of the genus Siagona: Siagona jenissoni, Siagona dejeani and Siagona europaea. These carabids have a stenotopic lifestyle in Mediterranean clayey soils, inhabiting the ground fissure system formed during the dry season. All species have a Mediterranean distribution and are nocturnal olfactory hunters, and are strict ant predators. For morphometric measurements, we considered body length (mm), wing length (mm), antenna length (mm), head width (mm), trochanter length (mm), number of ommatidia, eye surface area (mm2), ommatidia density (number of ommatidia/mm2 of eye surface area), head height (mm), thorax height (mm) and abdomen height (mm). The data revealed intersexual and interspecific differences. The three species differ in relative length of the antennae, density and number of ommatidia and relative trochanter length. Significant differences occurred in wing sizes, which are well developed in Siagona europaea, the only species capable of flight. When eye size is compared with other ground beetles of various lifestyles, Siagona shows pronounced "microphthalmy" an adaptation to subterranean life in clayey crevices of tropical and subtropical climates with a marked dry season.
在步甲科甲虫中，生理和行为特征反映了特定的栖息地需求，并且在具有不同生活方式的物种中，身体形态与习性之间存在很强的相关性。在本研究中，我们比较了西阿戈纳属（Siagona）的三个物种：詹氏西阿戈纳（Siagona jenissoni）、德氏西阿戈纳（Siagona dejeani）和欧洲西阿戈纳（Siagona europaea）的形态测量学特征和复眼特征。这些步甲科甲虫在地中海粘性土壤中具有狭域性的生活方式，栖息于旱季形成的地面裂缝系统中。所有物种都分布于地中海地区，是夜行性嗅觉猎手，并且是严格的蚂蚁捕食者。对于形态测量，我们考虑了体长（毫米）、翅长（毫米）、触角长（毫米）、头宽（毫米）、转节长（毫米）、小眼数量、眼表面积（平方毫米）、小眼密度（每平方毫米眼表面积的小眼数量）、头高（毫米）、胸高（毫米）和腹高（毫米）。数据揭示了两性间和种间差异。这三个物种在触角的相对长度、小眼的密度和数量以及转节的相对长度方面存在差异。翅的大小存在显著差异，欧洲西阿戈纳的翅发育良好，它是唯一能够飞行的物种。当将眼睛大小与各种生活方式的其他地甲虫进行比较时，西阿戈纳表现出明显的“小眼症”，这是对热带和亚热带气候且旱季明显的粘性裂缝中地下生活的一种适应。
