First Records of Butterflies (Lepidoptera)
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First Records of Butterflies (Lepidoptera) from the Republic of Nauru1 Donald W. Buden2,3 and W. John Tennent4 Abstract: Four species of butterflies are reported from Nauru for the first time and as first records of butterflies from the island republic. None is endemic. Three of the four species are widespread in Oceania: Badamia exclamationis (Fabricius), Danaeus plexippus (Linnaeus), and Hypolimnas bolina (Linnaeus). The other, Petrelaea tombugensis (Ro¨ber), belongs to a genus that also is wide- spread in the Pacific. The small number of widespread species found on Nauru is comparable with the situation encountered on other small, remote, low-lying Pacific islands. In the most recent checklist of butterflies Study Area of Pacific Ocean islands, Tennent (2006) re- The Republic of Nauru (0 30 0 S, 166 56 0 E) marked on the absence of records from Na- consists of a single, small (21 km2), raised uru, Midway, and Johnston Atoll among the atoll island in the west-central Pacific Ocean, numerous states, countries, and isolated is- approximately 2,100 km northeast of New lands and island groups within this vast area. Guinea (Figure 1). The nearest island is Ba- Froggatt (1910:407) remarked that ‘‘butter- naba (¼ Ocean) Island, 300 km to the east. A flies were rare’’ on Nauru based on informa- roughly 100 to 300 m wide coastal belt abuts tion provided by F. W. Steel, who collected a scarp that rises about 30 to 40 m (maximum insects on Nauru on some earlier but un- specified date. Butterflies seen by Steel were elevation 72 m at Command Ridge) to form the edge of a central plateau. Approximately apparently neither identified nor collected. 10,000 islanders reside on the coastal belt Hambruch (1915) included butterflies (using the German word schmetterling and the and in a small settlement centered around a brackish lake (Buada Lagoon) in a low-lying Nauruan word ijojimena) in a list of the fauna area on the southwestern part of the plateau. of Nauru; his accompanying illustration Coastal vegetation consists largely of strand, (Hambruch 1915:202, fig. 296) is a poorly scrub, scattered coconut trees, and a variety rendered generalized diagram of a butterfly of ornamentals and fruit trees. Much of the unidentifiable as to species. A collection of original vegetation of the central plateau was 41 butterflies recently made by D.W.B. is stripped away during a century of opencast the basis for this report and the first records phosphate mining, but many of the previ- of butterflies from the Republic of Nauru. ously mined areas have since regenerated to scrubland and have small pockets of residual forest dominated by Calophyllum inophyllum (Clusiaceae) and Ficus prolixa (Moraceae). The most extensive remnant forest areas are 1 Manuscript accepted 10 October 2007. 2 Corresponding author. on the slopes of the scarp and at its base. 3 Division of Natural Sciences and Mathematics, More detailed descriptions of the physiog- College of Micronesia-FSM, P.O. Box 159, Kolonia, nomy and vegetation of Nauru are provided Pohnpei, Federated States of Micronesia 96941 (e-mail: by Manner et al. (1984), Thaman (1992), and [email protected]). 4 Department of Entomology, The Natural His- Thaman et al. (1994). tory Museum, London SW7 5BD, England (e-mail: [email protected]). materials and methods Pacific Science (2008), vol. 62, no. 4:495–498 One of us (D.W.B.) visited Nauru during : 2008 by University of Hawai‘i Press 12–25 December 2006 and 30 March–5 April All rights reserved 2007 to conduct surveys of butterflies, drag- 495 496 PACIFIC SCIENCE . October 2008 Figure 1. Location map for Nauru and surrounding islands: B, Banaba (¼ Ocean Island); C, Chuuk; K, Kosrae; Kir, Kiribati; Mar, Marshall Islands; P, Pohnpei; PNG, Papua New Guinea; Van, Vanuatu. onflies, reptiles, and birds. The 41 specimens terfly glimpsed briefly in scrubland on the of butterflies collected during these visits central plateau during early evening on 23 were deposited in The Natural History Mu- December probably was this species. seum, London, and, together with personal observations, form the basis for this report. Family Lycaenidae Petrelaea tombugensis (Ro¨ber, 1886). 25 speci- results mens. Although field surveys began on 12 De- Family Hesperiidae cember, this species was not encountered un- Badamia exclamationis (Fabricius, 1775). one til 16 December, when only one was observed specimen. and collected. Others were seen with increas- A solitary female B. exclamationis was ing frequency (up to dozens per day) during collected at the edge of a small grove of Cal- the remainder of the December visit, mainly ophyllum inophyllum trees surrounded by in scrubland on the central plateau. They scrubland on the plateau, 31 March 2007; were often observed two or more in close two to three others seen during the March– proximity to each other and usually on or April visit eluded capture. A fast-flying but- near Premna serratifolia (Verbenaceae) and Butterflies of Nauru . Buden and Tennent 497 Calophyllum inophyllum. During early April, Hypolimnas bolina) are widely distributed this species was especially common among throughout Oceania and well beyond. shrubs and small trees on the ridgeline at the Although the genus Petrelaea is distributed edge of the central plateau and seemingly widely in the Indo-Pacific region, it is often attracted to Morinda citrifolia (Rubiaceae), overlooked, due in part no doubt to small Premna serratifolia, and Colubrina asiatica size, inconspicuous appearance, and a gen- (Rhamnaceae); several ‘‘pairs’’ were observed eral wariness (Tennent 2002:83). Corbet in close proximity to each other, flying in and Pendlebury (1978:270) reported P. dana tight circles for several seconds before sepa- ‘‘males . not uncommon . the female is rating and disappearing from view (probably rarely taken’’ in Malaysia, and Parsons males exhibiting territorial behavior). This (1998:420) reported P. tombugensis as ‘‘gener- species and its congener, P. dana (de Nice´- ally and locally rare’’ in Papua New Guinea. ville, 1883), are indistinguishable based on ex- Tennent collected P. tombugensis from several ternal characters. Identity has been confirmed of the Solomon Islands in 1996 and 1997 but in this case by genitalic examination (cf. Fu- only saw a small number of males (and no jioka and Chiba 1998). females) during many months in the field (Tennent 2002:83). Several male P. tombugen- Family Nymphalidae sis collected on islands of Vanuatu in 2002 Subfamily Danainae represented the first records of this species from that island group and a substantial east- Danaus plexippus (Linnaeus, 1758). six speci- ward extension of the genus (Tennent 2004); mens. the Nauru records represent the northeastern- Monarch butterflies were regularly ob- most limit of its range. It is interesting that served along the coastal belt, almost always P. tombugensis was the only lycaenid species in close proximity to ornamental shrubs of found on Nauru during this survey, that it Calotropis gigantea (Asclepiadaceae), a known was encountered in some numbers, and that host plant, in yards and along roadsides. specimens included five females. Taking ac- Three to six D. plexippus were often observed count of a historical extension of taxa from together at a single plant or small group of the west, one might expect to find other ly- plants. Solitary specimens were seen infre- caenid genera (e.g., Jamides Hu¨bner, Naca- quently on the central plateau where C. duba Moore, or the tiny ‘‘grass’’ blues Zizina gigantea was absent, and they were more Chapman and Zizula Chapman) that occur common in December than in March/April, farther east in the Pacific. when no more than five were observed over The nine specimens of Hypolimnas bolina a period of a week. collected on Nauru include three males and six females. Females of this species are highly Subfamily Nymphalinae polymorphic (the males much less so), and many female ‘‘forms’’ in the Pacific have Hypolimnas bolina (Linnaeus, 1758). nine been given individual names: see Tennent specimens. (2006:181) for additional remarks on these This species was observed in small num- forms. In coloration and pattern, two of the bers (three to four per day) throughout the is- males from Nauru are typical of H. bolina land during both the December and March/ throughout its Pacific range, but the third is April visits, and usually in shrubby, weedy, an unusual form with greatly reduced white grassy areas. markings on the upper surface and an almost unmarked undersurface (i.e., lacking the usual discussion white bands). Of the females from Nauru, all but one are fundamentally f. nerina Fabricius, Only four species of butterflies are re- 1775, with some minor variation. However, corded from Nauru; none is endemic. Three one is of a rather unusual form (except on (Badamia exclamationis, Danaus plexippus, and the Fiji Islands, where it appears to occur fre- 498 PACIFIC SCIENCE . October 2008 quently [see Poulton 1924]), in which both Hambruch, P. 1915. Nauru. Ergebnisse der surfaces are almost uniformly dark brown, Su¨dsee-Expedition 1908–1910. II. Ethno- with hardly any trace of the orange or white geographie: B. Mikronesien, Band 1, 2 markings typical of f. nerina. Without excep- Halbband. L. Friederichsen and Co., tion, the specimens of H. bolina collected have Hamburg. torn wings, suggestive of attacks by potential Manner, H. I., R. R. Thaman, and D. C. predators, such as birds and lizards. Hassall. 1984. Phosphate mining induced Additional surveys, particularly at different vegetation changes on Nauru Island. Ecol- times of the year, may add to the list of spe- ogy 65:1454–1465. cies. However, a meager butterfly fauna such Parsons, M. J. 1998. The butterflies of Papua as apparently occurs on Nauru is typical of New Guinea: Their systematics and biol- small, remote, and ecologically impoverished ogy.