以形態特徵探討臺灣產紋胸大蕈蟲族之親緣關係

Abstract

中文摘要 紋胸大蕈蟲族 (Encaustini) 是屬於鞘翅目 (Coleoptera) 大蕈蟲科 (Erotylidae) 大蕈蟲亞科 (Erotylinae)。大蕈蟲亞科的種類大多取食真菌，具棍棒狀觸角且末端三到五節膨大。紋胸大蕈蟲族下有兩個亞族，分別是紋胸大蕈蟲亞族 (Encaustina) 和肩紋大蕈蟲亞族 (Megalodacnina)，這兩個亞族可以藉由前胸腹板的突起、小顎內葉齒鉤數以及跗節延展程度來做區分。往昔研究中，此兩個亞族皆曾被視為獨立的單系群，但各分類群間之親緣關係並不明確，特別是肩紋大蕈蟲亞族與各族間之親緣關係變異甚大，且有部分類群如黃紋大蕈蟲屬 (Episcapha) 未曾被研究過。因此，本研究使用22個紋胸大蕈蟲族之屬級成員，以及出尾蟲科 (Nitidulidae) 與大蕈蟲科擬叩頭蟲亞科 (Languriinae) 等其他類群做為外群，並使用 59 種不同外部形態特徵來進行親緣關係研究，資料分析係利用 MrBayes 3.1.2 以及 PAUP beta 4.0 來重建親緣關係樹。研究結果顯示紋胸大蕈蟲亞族 (Encaustina) 為單系群，但黃腹大蕈蟲屬 Hornerotylus 依據親緣關係樹、頭後側的發音鑢以及小顎內葉上的齒鉤等特徵，較為接近迷你大蕈蟲族 (Tritomoni) ；而紋胸大蕈蟲亞族、迷你大蕈蟲族及細身大蕈蟲族關係較近；肩紋大蕈蟲亞族並非單系群，且此亞族的分類及親緣關係，仍有許多不清楚的地方，需要更多的研究來加以探討。

The beetles of the tribe Encaustini belong to the subfamily Erotylinae (Coleoptera: Erotylidae), so called the pleasing fungus beetles. These beetles usually feed on many kinds of fungi, with 3-5 segmented clubs on the apex of the antennae. The tribe Encaustini is usually separated into two subtribes, Encaustina and Megalodacnina. The characteristics to distinguish these two subribes are the keel-like process on the prosternum, the hook number on the laciniae of maxillae and the transverse tarsi. Although both two subtribes are considered as monophyletic groups in the previous studies, the relationship between these two groups is still unclear, especially the relationships of the Megalodacnina: relationships of some genera like genus Episcapha haven’t been studied. In this study, 8 genera belong to Encaustini are included. Other materials like Nitidulidae and Languriinae are treated as outgroups, and 59 morphological characteristics are used in this study, and the data is analyzed by Mrbayes 3.1.2 and PAUP beta 4.0. The results show that Encaustina is a well-supported monophyletic group except for the genus Hornerotylus, but Megalodacnina might be a paraphyletic group. The Encaustina is much closer to the other two tribes, Tritomini and Dacnini. The genus Hornerotylus, which was placed into Encaustina, is a member of Tritomini in the study, probably because of the stridulatory organs behind head and the reduce number of the hooks on the lacninae. The results also presented some controversies in the phylogenetic relationship and the taxonomic characters of the subtribe Megalodacnina, and it might need to study more other species of this subribe to solve these problems.