尾蜆蝶於臺灣的系統分類問題

Abstract

依照現行分類處理，蜆蝶科之銀紋尾蜆蝶(Dodona eugenes)有七個亞種，其中兩個亞種分布於臺灣：分別為北部的 ssp. formosana 以及中南部的 ssp. esakii，兩者僅在體型、翅紋以及寄主植物利用有少許不穩定的差異。除臺灣的亞種級的分類問題外，銀紋尾蜆蝶複合群(D. eugenes species complex)亦存在許多分類疑問。本種過去缺乏亞種間及近緣種間的比較，對於兩亞種如何共存於臺灣以及臺灣族群的分類地位皆尚未釐清。本研究以寄主植物利用、生殖器形態及粒線體DNA、核DNA序列等特徵檢視銀紋尾蜆蝶於臺灣的兩亞種是否存在分化，並取樣尾蜆蝶屬12種17個分類群，藉粒線體DNA、核DNA序列建構譜系關係及比較其生殖器形態特徵以釐清本屬各分類群之親緣關係。結果顯示銀紋尾蜆蝶於臺灣的兩亞種在寄主植物利用、生殖器形態及序列特徵皆無差異，ssp. esakii應為ssp. formosana之同物異名。尾蜆蝶屬成員之親緣關係樹與生殖器形態高度一致，銀紋尾蜆蝶呈一多系群，臺灣族群的姊妹群應為大斑尾蜆蝶(D. egeon)。基於粒線體DNA、核DNA序列及生殖器形態等特徵之差異，臺灣的尾蜆蝶應當視為一異於銀紋尾蜆蝶之獨立物種，並應提升為種級階層：Dodona formosana stat. rev.。

The Tailed Punch, Dodona eugenes, contains seven subspecies currently recognized. Two of them, namely ssp. formosana in northern Taiwan and ssp. esakii in central and southern Taiwan, are hard to distinguish due to their ambiguous diagnostic characters on body size, wing pattern, and host plant utilization. Other than these taxonomic status of subspecies of D. eugenes in Taiwan, systematic problems are also found in D. eugenes species complex. In the first part of this study, we clarify the taxonomic status of the two subspecies of D. eugenes in Taiwan using evidences provided by host plant utilization, genital characters, and molecular sequences (cox1, cox2 and Ef-1α). Secondly, by using molecular sequences (cox1, cox2 and Ef-1α) for each of 3 outgroup and 17 taxa of genus Dodona, we constructed phylogenetic tree of this genus and checked the congruence between phylogenetic tree and genital character of each taxon. Our results showed that there is no significant difference between the two previously recognized subspecies in Taiwan on host plant utilization, morphology of genitalia and molecular data, therefore, ssp. esakii probably should be regarded as a junior synonym of ssp. formosana. The phylogenetic tree and genital character showed considerable congruence, but D. eugenes under present usage emerged as a polyphyletic assemblage in the phylogenetic tree, and population in Taiwan is sister to D. egeon. Based upon the proposed phylogeny, the following nomenclatural change are made: Dodona eugenes formosana is raised to specific status as Dodona formosana Matsumura, stat. rev.