The Bornean members of the genus Leptogomphus Selys are revised. Two new species are described: Leptogomphus schieli sp. nov. (holotype ♂, Gunung Penrissen, Kuching Division, Sarawak, Malaysia, to be deposited in BMNH) and Leptogomphus sii sp. nov. (holotype ♂, Sungai Sii, upper Baram, Miri Division, Sarawak, Malaysia, in RMNH). Leptogomphus mariae Lieftinck, 1948 is considered to be a junior synonym of L. coomansi Laidlaw, 1936. The true male of L. pasia van Tol, 1990 is described for the first time; male specimens previously treated as L. pasia or L. cf pasia actually belong to a taxon closely allied to, and possibly merely a form of, L. coomansi. A description is given of the female of another new species, but the species is not named in the absence of the male. Female specimens from south-western Sarawak, similar to L. williamsoni Laidlaw, 1912, are considered likely to also represent a distinct species. The female of L. pendleburyi Laidlaw, 1934 is described for the first time and fresh descriptions of the males of L. coomansi, L. pendleburyi and L. williamsoni, and the female of L. coomansi are given. Keys to both sexes, and distribution maps are given. A molecular analysis of the Bornean species (except L. schieli) using the COI and ITS markers is presented.
Tropical mountains are hot spots of biodiversity and endemism, but the evolutionary origins of their unique biotas are poorly understood. In varying degrees, local and regional extinction, long-distance colonization, and local recruitment may all contribute to the exceptional character of these communities. Also, it is debated whether mountain endemics mostly originate from local lowland taxa, or from lineages that reach the mountain by long-range dispersal from cool localities elsewhere. Here we investigate the evolutionary routes to endemism by sampling an entire tropical mountain biota on the 4,095-metre-high Mount Kinabalu in Sabah, East Malaysia. We discover that most of its unique biodiversity is younger than the mountain itself (6 million years), and comprises a mix of immigrant pre-adapted lineages and descendants from local lowland ancestors, although substantial shifts from lower to higher vegetation zones in this latter group were rare. These insights could improve forecasts of the likelihood of extinction and 'evolutionary rescue' in montane biodiversity hot spots under climate change scenarios.