臺灣狹肩褐蛉屬 (脈翅目：褐蛉科) 分類修訂與使用翅幾何形態測量方法開發新形態特徵

Abstract

褐蛉科 (Hemerobiidae) 為脈翅目(Neuroptera) 下第三大科，全世界約有600種。其中狹肩褐蛉屬 (Micromus)為其中一個世界廣布的大屬，但由於屬內變異極大，又缺乏明確定義的自衍徵，其單系性長期存有爭議。在臺灣，狹肩褐蛉屬除了同樣是最常見的褐蛉類群之外，亦是開發作為生物防治資材的目標。然而，最近一次的褐蛉物種的記錄整理已是25年前。本研究旨在回顧臺灣狹肩褐蛉屬物種的分類現況，除了以翅脈和生殖器的形態特徵鑑定物種外，也使用分子特徵進行物種界定。此外，本研究亦首次使用幾何形態測量學，針對過去較少可分析特徵的後翅為目標嘗試開發新特徵區分過去僅能用生殖器鑑定的物種。根據博物館標本及野外採集，共檢視臺灣7種狹肩褐蛉屬物種，包括M. numerosus、M. igorotus、M. yunnanus、M. calidus、M. linearis、M. timidus及2種新記錄種M. ramosus和M. tianmuanus，且在名錄中加入其他文獻記錄在臺灣的M. mirimaculatus。除此之外，也發現了1種新種M. sp.，中文暫命名為「網點斑狹肩褐蛉」。分子分析方面，定序粒線體基因COI及18S rRNA，利用貝氏推論及最大概似法重建親緣關係樹，並使用自動分組物種組裝 (ASAP) 方法進行物種界定。結果顯示大部分臺灣狹肩褐蛉屬物種可被區分，分子證據支持形態鑑定結果。另外也釐清M. ramosus雄蟲形態的疑慮。在幾何形態測量學分析中，標記後翅16個地標點並進行排序分析，結果發現物種間在翅膀形狀上存在顯著差異。若以典型變數分析後經留一法交叉驗證，得到分類模型的整體正確率達64.1%，其中M. igorotus及M. calidus正確率最高，超過80%。以主成分分析結果去除變異較小的地標點，重新篩選8個地標點再分析後，留一法交叉驗證的結果準確率達80.4%，且除M. timidus和M. numerosus外物種的正確率皆100%。從兩次分析皆發現後翅M脈分岔的位置有明顯的變異，可作為分類特徵的參考。綜合形態學及分子證據，本研究釐清了臺灣狹肩褐蛉屬物種的分類現況，同時，幾何形態測量學的應用也展現了其在其他昆蟲分類上的潛力，後續可朝向更精細的研究設計，提供高解析度的分類線索。

The Hemerobiidae family is the third largest family of the order Neuroptera, comprising approximately 600 species worldwide. Even though Micromus is the largest genus; however, the absence of solid synapomorphies cast doubt on its monophyly. In Taiwan, Micromus species are the most common brown lacewings, also potential biological control agents. However, the last comprehensive record of Hemerobiidae species in Taiwan was made 25 years ago. This study aims to review the current taxonomic status of Micromus species in Taiwan. In addition to identifying species using traditional morphological traits, this study is the first to delimit brown lacewings species with molecular data. Furthermore, we attempt to use wing geometric morphometrics to increase the analyzable morphological traits and aid in the identification of morphologically similar species. A total of seven Micromus species in Taiwan were examined from museum specimens and field collections, including M. numerosus, M. igorotus, M. yunnanus, M. calidus, M. linearis, M. timidus, and two newly recorded species M. ramosus and M. tianmuanus. The species list also includes M. mirimaculatus, previously recorded in Taiwan from other literature. Additionally, a new species was also described, temporarily named M. sp., or "Net-spotted brown lacewing" in Chinese. For molecular analysis, mitochondrial gene COI and 18S rRNA were sequenced. Phylogenetic trees were reconstructed using Bayesian inference and maximum likelihood methods, and species delimitation was performed using the Assemble Species by Automatic Partitioning (ASAP) analysis. Results showed that most Taiwanese Micromus species could be differentiated, with molecular evidence supporting morphological identification. Also, the doubted morphology of male terminalia of M. ramosus is comfirmed. In geometric morphometrics analysis, 16 landmarks on the hindwing were marked, revealing significant differences in wing shape between species. Leave-one-out cross-validation of canonical variate analysis showed an overall model accuracy of 64.1%, with M. igorotus and M. calidus having the highest accuracy rates, exceeding 80%. A re-analysis using eight selected landmarks from principal component analysis results yielded an accuracy of 80.4%, with 100% correct identification for all species except M. timidus and M. numerosus. Both analyses indicated significant variability at the fork of the M vein, suggesting its potential as a taxonomic feature. Combining morphological and molecular evidence, this study clarifies the taxonomic status of Taiwanese Micromus species, laying the groundwork for future research on this group in Taiwan. The application of geometric morphometrics also demonstrates its potential in more insects, encouraging further detailed studies to provide high-resolution classification clues.