BioFormosa（2013）48: 13-16

Prosotas gracilis gracilis Röber, 1886, a New Record of Blue Found in Lanyu, Taiwan (, , Lycaeninae, )

Yu-Feng Hsu1*, Hang-Chi Huang2 1Department of Life Science, National Taiwan Normal University Taipei, Taiwan 2Butterfly Conservation Society of Taiwan Taipei, Taiwan

(Received: 21 February 2013, accepted: 15 April 2013)

ABSTRACT

One individual of female Prosotas gracilis Röber, 1886 was collected from canopy of tropical forest in Lanyu, representing a lycaenid butterfly species unrecorded in Taiwan. This Prosotas species is widespread but uncommon throughout the Indo- Australian Region. The individual found in Lanyu may be a straying one from the Philippines, or P. gracilis may actually inhabit Lanyu, but seldom sighted as it may be a canopy-dweller.

Key words: canopy, straying butterfly, the Philippines

Introduction distributional range also known to include Sulawesi (Vane-Wright and de Jong, 2003) and the As lycaenid belonging to the Philippines (Takanami and Seki 2001; Treadaway Prosotas are small in size and similar among and Schroeder 2012). species (Eliot, 1992), some of them were discovered comparatively recent. For instance, Material and Methods Tennet (2003) described two new species of Prosotas from New Hebrides archipelago as recent The collected Prosotas specimen was as just a decade ago. In Taiwan, where the inventory compared with all the described species of the of butterflies was generally believed near genus using specimens deposited in the Natural completion decades ago, the presence of P. dubiosa History Museum, London, as well as literature to was not aware until 1990s. A specimen of Prosotas determine the taxonomic affinity of the material. previously unrecorded in Taiwan was recently Terminology follows Nijhout (1991) for wing collected from Lanyu, an island lies some 60 km patterns. east to the main island of Taiwan. The specimen was subsequently identified as a female individual Taxonomic note of P. gracilis as its diagnostic characters (provided by Seki et al., 1991 and Eliot, 1992) are conformed Prosotas gracilis gracilis Röber, 1886 to this taxon. Prosotas gracilis is a species (Figs A, B) widespread in the Indo-Australian Region but Plebeius gracilis Röber, 1886: 67. Type locality: uncommon or rare almost anywhere it is found Ceram. (Seki et al., 1991; Treadaway and Schroeder 2012; gerydomaculata Rothschild, 1915: 139. Parsons 1999). According to Tite (1963), four Type localty: Central Ceram. subspecies are recognized for P. gracilis. The Prosotas gracilis gracilis; Tite, 1963, Bull. Br. Mus. specimen collected from Lanyu appears to be nat. Hist. 13 (4): 96. conformed with the nominotypical subspecies, which was described from Ceram, but with Diagnosis.

*Corresponding author: Yu-Feng Hsu; FAX: 886-2-29312904; E-mail: [email protected]

Yu-Feng Hsu, Hang-Chi Huang

Figure A. Upperside of Prosotas gracilis gracilis ♀ collected from Lanyu; Figure B. Underside of Prosotas gracilis gracilis ♀ collected from Lanyu. Arrow indicates the diagnostic feature of the nominotypical subspecies of Prosotas gracilis.

A species with no tail on the hindwing. Wing Specimens examined. undersides with ground color tinged with ocher, 1 ♀ , TAIWAN: TAIDONG Co., Lanyu, bases darkened. The nominotypical subspecies of P. Sidaogou, III. 18/20. 2006. Coll. Y. F. Hsu & H. C. gracilis is distinguishable by the element “g” Huang. defined by Nijhout (1991) forming a prominent white band edged distally by a dark band (BMNH Discussion specimens, 5♂4♀). After the single individual of P. gracilis was Description. collected, efforts to obtain additional samples of the Measurements of sample found from Lanyu: species from Lanyu have been unsuccessful, that female: forewing length 20.0 mm (n = 1). included a 3-year butterfly monitoring practice Compound eyes hairy. Clubs of antenna flattened performed on monthly basis from 2008 through laterally. Wing uppersides: Ground color brown. A 2010. Usually butterfly and other vagile prominent, dark brown spot present at distal end in found in such a low frequency in southern part of cell CuA1. Metallic purple scalings present Taiwan are usually considered as straying species proximally on both forewing and hindwing, with from further south territories like the Philippines or former more extensive than latter. Wing undersides: Indochina. However, P. gracilis is rare throughout Ground color ochreous brown, darkened near bases. its distributing range (Seki et al., 1991; Treadaway Central symmetry system forming darker bands and Schroeder 2012; Parsons 1999), and rare edged by white. Distal bands of central symmetry species does not usually become straying species. system slightly bent inwards anteriorly on forewing, Moreover, it is known that many organisms strongly curved outwards medially and edged with inhabiting Lanyu are shared with the Philippines. prominent white bands on hindwing. Proximal Cheng and Lu (2000) pointed out that some 110 out bands of central symmetry system present, obscure of 800 or so vascular plants growing on Lanyu are on forewing, prominent on hindwing. Discal spots also found in the Philippines but not in Taiwan, as short, dark bars edged with white. Marginal although some 650 species are shared with Taiwan ocelli as a series of brown spot at distal end of each (of them some 500 species also grow in the cell, but in CuA1 cell as a prominent, dark brown Philippines). Lue et al. (1999) listed 19 species of spot crowned with orange. terrestrial reptiles (12 species of lizards and geckos and 7 species of snakes) inhabiting Lanyu, of them Bionomics. two species are found in the Philippines but not in The single individual was found on the wing Taiwan. Another fact worthy to be mentioned is that over canopy 16.2 m above the ground in a deep, most Philippine-originated straying butterflies are humid canyon covered by tropical forest. recorded in the autumn, when southwest seasonal

14 a New Record of Blue Butterfly Found in Lanyu, Taiwan

wind prevails. The possibility that P. gracilis Lue KY, Tu MC and Hsiang KS. 1999. The Reptiles actually inhabits Lanyu may not be ruled out. and Amphibians of Taiwan. [in Chinese] The larval hostplant of P. gracilis is unknown, Nijhout HF. 1991. The Development and Evolution not listed in the most comprehensive hostplant of Butterfly Wing Patterns. Smithsonian database established for butterflies in the Oriental Institution Press, Washington. Region by Robinson et al. (2001). Hsu and Yen Parsons M. 1999. The Butterflies of Papua New (2006) have demonstrated that both P. nora and P. Guinea, Their Systematics and Biology. dubiosa conceal ova among flower buds of larval Academic Press. hostplants, with larvae as exclusive flower-feeders. Robinson GS, Ackery PR, Kitching IJ, Beccaloni Both species may utilize several plant families as GW and Hernández LM. 2001. Hostplants of larval hosts, but trees in Fabaceae (legumes) appear the Moth and Butterfly Caterpillars of the to be favored hosts. P. gracilis may share the Oriental Region. The Natural History Museum, flower-feeding habit with these Prosotas species. London. Seki Y, Takanami Y and Otsuka K. 1991. Butterflies Acknowledgements of Borneo, Vol. 2. No. 1. Lycaenidae. Tobishima Corp., Tokyo. We thank Jim Reynold (the Natural History Takanami Y and Seki Y. 2001. A synonymic list of Museum, London) for allowing us to examine the Lycaenidae (Lepidoptera) from the Philippines, collection under his attendance when the senior edition 12. Available from author visited the museum in 2006. We also thank [http://www.asahi-net.or.jp/ Kazuhiro Morishita (Yokohama City Museum, ~EY4Y-TKNM/philframe.html] (accessed 2 Japan) for providing literature relevant to the September 2006) present article. Tennet WJ. 2003. Two elusive new Prosotas Druce, 1981 (Lepidoptera, Lycaenidae) References from the New Hebrides archipelago (Solomon Islands and Vanuatu). Butterflies 36: 39-44. Cheng HW and Lu SY. 2000. Botel Tabaco, Yami & Tite GE. 1963. A synonmic list of the genus Plants. Lamper Enterprises Co., Ltd., 268 pp. Nacaduba and allied genera (Lepidoptera: [in Chinese] Lycaenidae). Bull. Br. Mus. (nat. Hist.) Eliot JN. 1992. The Butterflies of the Malay Entomol. 13: 69-116. Peninsula, 4th edition. Malayan Nature Treadaway CG and Schroeder HZ. 2012. Revised Society, Kuala Lumpur. checklist of the butterflies of the Philippine Hsu YF and Yen SH. 2006. Immature biology of Islands (Lepidoptera: Rhopalocera). Prosotas reveals an ovipositing strategy Nachrichten des Etomologischen Vereins unusual in polyommatine lycaenids Apollo Supplementum 20: 1-64. (Lepidoptera, Lycaenidae, ) Vane-Wright RI and de Jong R. 2003. The with a description of a new subspecies of P. butterflies of Sulawesi: annotated checklist for dubiosa from Taiwan. Zoological Studies 45: a critical island fauna. Zool. Verh. Leiden 343: 308-321. 3-267, 14 figs, 16 pls.

15 生物學報（ 2013）48：13-16

從蘭嶼發現之臺灣新記錄種灰蝶：窄翅波灰蝶 Prosotas gracilis gracilis Röber, 1886 (鱗翅目：灰蝶科：灰蝶亞科：藍灰蝶族)

徐堉峰 1* 黃行七 2 1 國立臺灣師範大學生命科學系 2 臺灣蝴蝶保育學會

（收稿日期：2013.2.21，接受日期：2013.4.15）

摘 要

本文報告由蘭嶼樹冠層採獲之臺灣過去未曾記錄之波灰蝶屬種類雌蝶個體，經檢視結果標本特 徵符合 Prosotas gracilis gracilis Röber, 1886，該物種種小名 gracilis 為拉丁文苗條 、纖細之意，用以 說明這種灰蝶的雄蝶與其他波灰蝶相較，翅形格外狹窄縱長的特性，據此在本文將之稱為窄翅波灰 蝶。窄翅波灰蝶於印度澳太地區分布廣泛，但在各地均頗為罕見。牠在蘭嶼出現可能代表源自菲律 賓的偶產個體，但也有可能牠原本便棲息在蘭嶼，只是因棲息於樹冠層，因此難以觀察。

關鍵詞：樹冠層、偶產蝶、菲律賓

＊通信作者：徐堉峰（ Yu-Feng Hsu）；FAX：886-2-29312904；E-mail：[email protected]