Chrysomelidae of the Lesser Sunda Islands: Wallace’S Line and the Crossing of Worlds

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Chrysomelidae of the Lesser Sunda Islands: Wallace’s Line and the crossing of worlds

Plate 3–26 Mohamed S. Mohamedsaid1 Abstract. Th e Lesser Sunda Islands (LSI) is a chain of islands consisting of Lombok, Sumbawa, Sumba, Flores, and Timor. Based on published records combined with results from present survey, Chrysomelidae from LSI are represented by 144 species, including 59 new records and 63 endemics (44%). Th e new records represent an increase of 69% from the previous 85 recorded species. LSI has strong affi nity with the Oriental biogeographic Region with 41% of its fauna are derived from the Region. Although LSI is part of the Australasian biogeographic Region, the representation from Australia and New Guinea is very small, about 3%. Th e fi ve major subfamilies present in LSI are the Galerucinae (30%), followed by Alticinae (24%), Eumolpinae (15%), Cassidinae (15%) and Hispinae (6%). Species richness of the islands in LSI de- clines from west to east and further from the mainland (Sundaland). Th e same is true with the Oriental Region representatives; they decline in abundance from west to east further away from Wallace’s Line, a biogeographic demarcation between the Oriental and Australasian Regions. But decline of the Oriental elements is compensated by an increase in species endemism. Th e Wallace’s Line appears to be a faunal barrier, where a large number of genera and species, particularly from the Galerucinae are restricted to Sundaland, a subregion of the Oriental Region. Th e following six genera are not represented in Sundaland: Cleoporus and Dematochroma ( Eumolpinae), Paropsis and Paropsisterna ( Chrysomelinae), and Calomicrus and Paraplotes ( Galerucinae).

Keywords. Diversity, distribution, species list, endemics, new records, origins, Lesser Sunda Islands, Wallace’s Line, faunal barrier, Sundaland, Wallacea, Oriental Region, Australasian Region.

1. Introduction Th e Lesser Sunda Islands (LSI) is a chain of islands that lies to the east of Bali and extends eastwards from Lombok, Sumbawa, Sumba, Flores, and Timor. It forms the

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Research on Chrysomelidae, Volume 2, pp. 57–104, © Koninklijke Brill, Leiden, 2009 58 Mohamed S. Mohamedsaid southern arc of central Indonesia forming a link between Java and Timor (Fig. 1), stretching for about 1000 kilometer west to east. Th e famous Wallace’s Line runs along the deep Lombok Straits, that span between Bali and Lombok, is separating Sundaland, a subregion of the Oriental Region, and Wallacea, a subregion of the Australasian Region. Wallacea, which include LSI, Sulawesi, and Maluku contain a mix of fl ora and fauna from Asian and Australian elements. For about 150 years, LSI, Sulawesi and Maluku have attracted great interest from botanists, zoologists, including entomologists, biogeographers, geologists, and anthropologists. Th e geological history of LSI is complex. In the Late Mesozoic about 70 million years ago, the region was created by subduction and partial melting of the Austral- ian tectonic plate below the Eurasian Plate (Monk et al. 1997). Lombok, Sumbawa and Flores are volcanic in origin, whereas Sumba and Timor are non-volcanic consisting of raised coral reefs and deposits (Plate 26). In 1815, the island of Sumbawa saw the eruption of Mount Tambora with the force of an explosion much bigger than the Krakatau in 1883. Recently, in April 2008, Mount Egon in Flores erupted causing the evacuation of hundreds of people from villages around the volcano. Th e LSI has an average annual rainfall of 1350 mm, the driest in the Malay Ar- chipelago. Th e dry climate has led to distinct vegetation types, primarily monsoon forests, and savanna woodlands (Plate 25). Monsoon forests contain a mix of moist deciduous forest and dry deciduous forest, dry thorn forest, and dry evergreen forest (Plate 24). Th e fl oristic composition between islands of volcanic and non volcanic origin do not diff er signifi cantly (Van Steenis 1979). Th e Chrysomelidae of LSI, a subset of Wallacea, had been neglected for more than one hundred years since their original descriptions. From published records, LSI is represented by 85 species in 45 genera and 11 subfamilies (Monrós 1958; Kim- oto 1984a, 1984b, 1985a, 1985b, 1990a, 1990b, 1998, 2000, 2001; Borowiec 1990, 1995, 2006; Swietojanska & Borowiec 1999; Swietojanska 2001; Medvedev 2008). Th e fi rst chrysomelid species recorded from LSI was Rhypharida vittipennis Jacoby, 1864, a eumolpine beetle described from Flores. Hemipyxis sulphurea Jacoby, 1894 was the fi rst species described from Lombok; Oides fl avipes Duvivier, 1884 from Sum- bawa; Luperomorpha sumbaensis Jacoby, 1899 from Sumba; and Clytra bella (Baly, 1865) from Timor. Aft er a lapse of more than fi ft y years, a cassidine was described from Sumba, Laccoptera sutteri Hincks, 1953. Towards the end of the last century two cassidines were described from the region, Cassida timorensis Borowiec, 1995 from Timor and Notosacantha sumbawaensis Swietojanska & Borowiec, 1999 from Sumbawa. At the beginning of this century a cassidine was described from Timor, Aspidimorpha timorensis Swietojanska, 2001. Five years later, Borowiec (2006) described another tortoise beetle from Sumba, Basiprionota sumba Borowiec. Th en in 2008, saw four new species were described from Lombok: Paraplotes granulata Medvedev (Galerucinae), Hespera foveipennis Medvedev, H. lombokana Medvedev, and Nisotra insulana Medvedev ( Alticinae).