北台灣細胸珈蟌之翅色多型性

Wing Color Polymorphism of the Damselfly Mnais tenuis in Northern Taiwan

在台灣已有報告指出細胸珈蟌（Mnais tenuis）翅色型為性內多型性，雄蟌具有翅色二型性，雌蟌則有一至三種翅色型的不同看法。因此本研究的目的是以定量的方法，檢視細胸珈蟌翅色性內多型性，以及初羽化期與成熟期的珈蟌在形態上的差異。於2012 年3 至4 月在台灣北部採樣286 隻成蟲個體，測量它們的翅翼透明度、翅翼面積與體型大小等三種形態特徵，並以翅翼透明度的分布不連續判斷翅色型。結果顯示雄蟌具有「橙翅型」與「透翅型」二型性，雌蟌僅具有「透翅型」單型性，雌雄總共三種翅型。以變異數分析及Mann-Whitney U test，分別比較此三種翅型及初羽化期與成熟期在這三種形態特徵上的差異，結果顯示透翅型雄蟌翅翼面積與體型皆顯著小於橙翅型雄蟌與透翅型雌蟌（p < 0.001），翅翼透明度則與雌蟌無顯著差異（p > 0.05）。就這三種翅型而言，成熟期的珈蟌在體型上皆顯著地大於初羽化期的珈蟌（p < 0.001）。而翅翼透明度與翅翼面積只有在成熟期橙翅型雄蟌與初羽化期橙翅型雄蟌之間有顯著差異（p < 0.001）。

The damselfly Mnais tenuis adults in Taiwan are reported to possess intra-sexual polymorphism in wing color. Male adults have two wing-color forms, but female adults have been indicated with doubt to have one to three wing-color forms. Therefore, this study was aimed to quantitatively examine wing-color polymorphisms of Mnais tenuis and to determine the differences in morphological features of adults between the teneral stage and mature stage. A total of 286 Mnais tenuis adult individuals were collected in northern Taiwan from March to April 2012. The features of these individuals, such as wing transparency, wing area, and body size, were measured, and the discrete distribution of wing-color morphs was examined according to wing transparency. A total of three morphs were identified from the discrete distribution where the males can be classified as the ”orange-winged form” or ”clear-winged form”, while the females classified as a single ”clear-winged form”. Furthermore, the analysis of variance (ANOVA) was used to compare these features among the three morphs, and Mann-Whitney U test between teneral stage and mature stage. The results indicate that the wing area and body size of clear-winged males were significantly lower than those of both orange-winged males and clear-winged females (p ＜ 0.001). But there was no significant difference in wing transparency between clear-winged males and females (p ＞ 0.05). The mature adults were heavier than teneral adults for all three morphs (p ＜ 0.001). However, the significant differences in wing transparency and wing area were found only between mature and teneral orange-winged males (p ＜ 0.001).