Island systems are important models for evolutionary biology because they provide convenient, discrete biogeographic units of study. Continental islands with a history of intermittent dry land connections confound the discrete definitions of islands and have led zoologists to predict (1) little differentiation of terrestrial organisms among continental shelf islands and (2) extinction, rather than speciation, to be the main cause of differences in community composition among islands. However, few continental island systems have been subjected to well-sampled phylogeographic studies, leaving these biogeographic assumptions of connectivity largely untested. We analyzed nine unlinked loci from shrews of the genus Crocidura from seven mountains and two lowland localities on the Sundaic continental shelf islands of Sumatra and Java. Coalescent species delimitation strongly supported all currently recognized Crocidura species from Sumatra (six species) and Java (five species), as well as one undescribed species endemic to each island. We find that nearly all species of Crocidura in the region are endemic to a single island and several of these have their closest relative(s) on the same island. Intra-island genetic divergence among allopatric, conspecific populations is often substantial, perhaps indicating species-level diversity remains underestimated. One recent (Pleistocene) speciation event generated two morphologically distinct, syntopic species on Java, further highlighting the prevalence of within-island diversification. Our results suggest that both between- and within-island speciation processes generated local endemism in Sundaland, supplementing the traditional view that the region's fauna is relictual and primarily governed by extinction. This article is protected by copyright. All rights reserved.

We describe a new species of Crocidura (Soricidae) from Sulawesi Island, Indonesia, documenting its novelty with both genetic and morphological characters. The new species is widespread on the island, with vouchered records from nine general localities distributed among five of the island’s areas of endemism. Morphologically, the new species is readily distinguished from all other described Sulawesi Crocidura by its intermediate body size, gray pelage, and long, hairy tail. The new species was mainly captured in pitfalls placed in the ground, but we also obtained evidence that it readily climbs trees and may be scansorial in its locomotor habits. Populations of the new species sampled from across the island are closely related, separated by < 0.02 uncorrected mitochondrial p-distances. The new species is one member of an endemic radiation of shrews on Sulawesi now known to contain six valid species and several undescribed species, all within the genus Crocidura. Resolution of species limits and phylogenetic relationships in this radiation is hindered by habitat loss at type localities, historical designation of new species using very small sample sizes, and a lack of genetic data from type specimens. Kami mendeskripsikan spesies baru Crocidura (Soricidae) dari Pulau Sulawesi, Indonesia, sekaligus mendokumentasikan keunikan karakter secara genetik maupun morfologi dari spesies tersebut. Spesies baru ini tersebar luas di Pulau Sulawesi, diketahui berdasarkan spesimen yang berasal dari sembilan lokasi umum yang tersebar di lima kawasan endemik di pulau tersebut. Secara morfologi, spesies baru ini dapat dibedakan dari spesies Crocidura lainnya dari Sulawesi berdasarkan ukuran tubuh yang sedang, rambut tubuh berwarna abu-abu, dan ekor yang panjang dan berambut. Spesies baru ini sebagian besar diperoleh dari perangkap sumuran yang ditanam didalam tanah, selain itu kami juga mendapatkan bukti bahwa spesies ini mampu memanjat pohon dan kemungkinan memiliki perilaku sebagai pemanjat. Beberapa populasi spesies yang dikoleksi dari Sulawesi ini mempunyai kekerabatan yang dekat, hanya dipisahkan oleh jarak proporsi DNA mitokondria (tidak terkoreksi) sebesar < 0.02. Spesies baru ini merupakan salah satu anggota dari suatu kelompok radiasi endemik cecurut di Sulawesi yang sampai saat ini diketahui terdiri atas enam spesies yang valid, dan beberapa spesies yang belum dideskripsikan, semuanya termasuk didalam genus Crocidura. Kepastian dalam menetapkan batasan jarak antar spesies dan hubungan kekerabatan genetik dari radiasi kelompok cecurut di Sulawesi terkendala oleh kerusakan habitat pada lokasi spesimen tipe, sejarah penamaan spesies yang hanya berdasarkan sampel yang sedikit, dan keterbatasan data molekuler dari spesimen tipe.