臺灣哺乳動物毛髮形態之光學顯微鏡與掃描式電子顯微鏡分析暨物種檢索表建置

Abstract

毛髮為哺乳動物綱（Mammalia）的特徵之一，具有隔熱保暖、物理性保護、偽裝與求偶等功能。由於不同物種間毛髮顯微形態的多型性（polymorphism）、毛髮對死後變化或化學傷害的良好抗性，加上檢體容易收集的特性，毛髮常作為協助辨識物種的研究載體。毛髮形態學（trichomorphology）亦被廣泛應用於多項領域，如：鑑識科學中的盜獵或動物虐待案件的物證鑑定、生態學中的食性與棲地調查，或考古學中古生物的鑑定與分類等等。而近年由於影像技術的進步，將掃描式電子顯微鏡（scanning electron microscope, SEM）應用於毛髮形態學的研究日益蓬勃，其相較一般光學顯微鏡更高的解析度與較大的景深（depth of field）有助於清晰呈現毛髮表面特徵，提升了以毛髮形態鑑定物種的潛能。現今世界各地已有多個針對不同地區的哺乳動物建立掃描式電子顯微鏡的毛髮辨識圖譜與檢索表（identification key）出版，惟臺灣目前仍未有系統性的哺乳動物毛髮分析，本研究之目的即為建立臺灣陸域哺乳動物之毛髮樣本資料庫，並結合分析毛髮角質層（cuticle）與髓質層（medulla）中量化與質化之顯微特徵，歸納出適用於臺灣哺乳動物的毛髮形態物種檢索表。本研究共囊括30種臺灣可見的陸生哺乳動物肩胛背側的覆毛，透過毛鱗片拓印玻片（cuticular cast）分析毛髮長度、最大寬度、毛鱗片間距與毛鱗片排列樣式等特徵，再經由全毛玻片（whole mount slide）分析毛髮長度、最大寬度、髓質指數（medullary index）與髓質細胞排列樣式等特徵。另針對5種蝙蝠的毛髮以掃描式電子顯微鏡輔助觀察。結果發現，表皮層之鱗片樣式於毛髮近端在不同物種間較具多樣性，為物種鑑別的理想觀察區段。而毛髮的長度、最大寬度、髓質指數、毛鱗片和髓質細胞的排列樣式皆具有不等程度的親緣相關性（phylogenetic relationship）並可作為協助物種鑑定的指標。另外，毛根、毛髮基部與毛尖之形態於部分目別或物種間亦具有特徵性。而蝙蝠的毛髮於掃描式電子顯微鏡下觀察到的形態有時可能因擺位差異而與光學顯微鏡下所見不同，但掃描式電子顯微鏡對於表面細節之呈像仍有助於對細小的蝙蝠毛髮的觀察。最後，透過整合物種間毛髮特徵所創建之毛髮形態檢索表，此30個物種可經量化與質化分析之差異被區分，其中亦囊括了過去文獻未有過相關毛髮形態紀錄的11個物種，包含：臺灣黑熊（Ursus thibetanus formosanus）、石虎（Prionailurus bengalensis chinensis）、鼬獾（Melogale moschata subaurantiaca）、臺灣小鼯鼠（Belomys pearsonii kaleensis）、白面鼯鼠（Petaurista lena）、大赤鼯鼠（Petaurista grandis）、臺灣野兔（Lepus sinensis formosus）、臺灣獼猴（Macaca cyclopis）、臺灣葉鼻蝠（Hipposideros armiger terasensis）、臺灣管鼻蝠（Murina puta）與東亞摺翅蝠（Miniopterus fuliginosus）。這是第一個針對臺灣陸域哺乳類毛髮形態較具系統性且成功統整出檢索表的研究，結果顯示此套簡易、快速的物種鑑定方法將來實務應用於輔助臺灣哺乳動物相關領域研究之潛力。

Hair is one of the characteristics of the class Mammalia, providing functions like thermoregulation, protection, camouflage, and social display. Due to the polymorphous microscopic morphology of hair among different species, its resistance to postmortem changes or chemical decomposition, and the accessibility of sample collection, hair is seen as an ideal research target to assist in species identification. Trichomorphology, the study of the morphology of hair, is widely applied in various fields, including forensic science for identifying evidence in cases of wildlife poaching or animal abuse, ecological studies with diet and habitat analysis, and the identification and classification of ancient mammals in archaeology. With the advancement of imaging technology, the application of scanning electron microscopes (SEM) in trichomorphology has flourished in recent years. SEM features higher resolution and greater depth of field compared to conventional optical microscopes, which helps clearly visualize the surface structures of hair and enhances the potential for species identification through hair morphology. Many hair identification atlases and keys targeting mammals from different regions worldwide have been published. However, systematic analysis of mammalian hair morphology in Taiwan is still lacking. Hence, this study aims to establish a hair sample database for terrestrial mammals of Taiwan, and to analyze quantitative and qualitative characteristics of the cuticle and medulla layers of hair using optical microscopy and SEM. The ultimate goal is to construct an identification key applicable to mammals of Taiwan with characteristic hair morphology. This study includes guard hairs collected from the dorsal scapular region in 30 terrestrial mammal species in Taiwan. Cuticular casts were made to analyze features such as hair length, maximum hair width, interscale distance, and scale patterns, while whole mount slides were prepared to analyze hair length, maximum hair width, medullary index, and medullary patterns. SEM was applied to assist in observing the hair of 5 bat species. The results showed that the scale patterns are more diverse among species in the proximal hair region, making it an ideal section for analyzing scale morphology. Besides, hair length, maximum hair width, medullary index, cuticular patterns and medullary patterns of hair all exhibited varying degrees of phylogenetic relationship among the analyzed species and could serve as indexes for species identification. The morphologies of the hair root, the hair base and the hair tip are also characteristic in some orders and species. As for the observation of bat hairs using SEM, although the results occasionally differ from those observed under the light microscope due to the positioning of the sample, SEM is still beneficial for analyzing fine bat hairs with its high resolution. Finally, a hair morphology identification key was established through the integration of hair characteristics among species, and the 30 species can be distinguished based on the quantitative and qualitative analyses. This study also covers hair morphology of 11 species without any previous documentation to the author’s knowledge, including Taiwanese black bear（Ursus thibetanus formosanus）, leopard cat（Prionailurus bengalensis chinensis）, Formosan ferret-badger（Melogale moschata subaurantiaca）, Formosan hairy-footed flying squirrel（Belomys pearsonii kaleensis）, Taiwan red-and-white giant flying squirrel（Petaurista lena）, Formosan giant flying squirrel（Petaurista grandis）, Formosan hare（Lepus sinensis formosus）, Formosan rock macaque（Macaca cyclopis）, Formosan leaf-nosed bat（Hipposideros armiger terasensis）, Taiwanese tube-nosed bat（Murina puta）and Eastern bent-wing bat（Miniopterus fuliginosus）. This is the first-ever research on the hair morphology of terrestrial mammals of Taiwan using a systemic method. The result suggests the potential of this simple and cost-efficient method of species identification to aid in future research on mammals of Taiwan.