Systematics, phylogeny, and biogeography of New Guinean Exocelina

The project examines the taxonomic and phylogenetic structure and biogeography of the genus Exocelina Broun, 1886 in New Guinea. The island is attractive for scientific research not only because it is one of only three remaining major tropical wilderness areas with a very rich biodiversity, but also because of the complexity of its geological origin and colonization history in combination with the scarcity of information on all of them. Although numerous papers on different insect groups of New Guinea have been published to date, no data on water beetles of the island were available until a study on diving beetles (Dytiscidae) was initiated by Dr M. Balke in 1995. The genus Exocelina (91 described species) is a recently discovered water beetle group with high levels of diversification and endemism throughout the Australian and Pacific Regions. The genus was first described as subgenus Papuadytes Balke, 1998 of the genus Copelatus Erichson, 1832 for more than 30 New Guinean species. As a result of transferring the Australian Exocelina advena Broun, 1886 into Papuadytes, the latter name became a synonym of the older genus name. New Guinea is the core of diversity of the genus, but it remains least studied. There is no key to identify the already described species and extensive recent fieldwork in New Guinea revealed the existence of more than 100 additional new species. No morphological and taxonomic work was carried out since the genus had been described, except for descriptions of several new species, whereas a number of phylogenetic examinations on Exocelina were conducted by Dr M.Balke using molecular data (DNA sequences). However, only 24 species were used in his phylogenetic analyses and only eight of them carried valid scientific names, the others were only classified using voucher numbers. Absence of described and named species acts as a brake on further molecular study of the genus, as it is crucial now to delimit species based on morphology, to understand where DNA sequence data fail to reveal recently diverged morphospecies and how many species there are in total. Adding formal descriptions and morphological data will also allow more detailed studies of patterns and processes involved in the species delineation of the New Guinean Exocelina, to test the hypothesis of the monophyletic nature of the group and its clades, and to study the phylogeny and evolution of the genus with a complex approach. The main project goal is to investigate the evolution of Exocelina in the complex geological and ecological environment of New Guinea. To fulfill this goal we will 1) carry out a taxonomic revision of the genus, with descriptions of the new species; 2) test species limits based on morphological characters and molecular data; 3) analyze relationships within the genus based on morphological characters and on molecular data separately; 5) carry out combined phylogenetic analysis, based on morphological characters and molecular data, including biogeographical and ecological aspects. The project will be carried out at the Naturhistorisches Museum Wien and is planned as an international cooperation with Dr M. Balke, Zoologische Staatssammlung München. We believe that our project is of great importance since it will bring new data in two aspects. First, its results will test/support several general theoretical and methodological hypotheses in biogeography, e.g. a long-distance dispersal might play a prominent role in the formation of the Southern hemisphere distributional patterns, and in systematics, e.g. a) success of an integrate approach for species delimitation; b) more than 100 species new to science will be described. Here, the most innovative aspect is the creation of a cybertaxonomy infrastructure for scientific publications: descriptions, keys, and digital imaging linked to Wiki-online resources. The second aspect is important for the group: a) for the first time, phylogenetic analyses of Exocelina will be performed based on morphological and molecular data, combined to the largest dataset for this region and invertebrates available to date, to reconstruct the biogeographical evolution of this group; b) a new supraspecific classification of Exocelina will be proposed; c) a first key, illustrated with drawings and digital images, will be created. Results of our project will have an implication not only for other biological disciplines (e.g. ecology, and nature inventory and conservation) but also for popularization of nature study and conservation and training of local people as parataxonomists.

Ever since Darwin and Wallace, island biodiversity and evolution of faunal diversity on islands have intrigued biologists. Our project examined the species magnitude, phylogenetic structure, and evolutionary origin of predacious diving beetles of the genus Exocelina Broun, 1886 in New Guinea.With an area of 800.000 km2, it is the second largest island in the world and ranked as one of only three remaining major tropical wilderness areas with a very rich biodiversity. Insects are tremendously diverse in New Guinea and play vital roles in providing ecosystem services, but remain poorly known, especially beetles. Predacious diving beetles (Dytiscidae) are carnivorous insects which can be found in almost all aquatic habitats and count over 4300 described species worldwide. At present, only slightly more than 170 species are recorded from New Guinea, however, their total number is steadily rising due to ongoing extensive survey work. The genus Exocelina was discovered less than 20 years ago and includes species, which occur in habitats associated with mountain streams, throughout the Australian and Pacific Regions. New Guinea is the core of biodiversity of the genus, with its representatives compiling more than 60% of the dytiscid fauna of the island. Therefore, our research focused on this insect group.During our project, we revealed and described 121 species and four subspecies new to science bringing the total number of New Guinea Exocelina to 157 species and four subspecies, created species-group structure of the genus that includes 26 species groups, made keys for species identification, studied their phylogenetic relationships and evolution of their morphology, examined important biogeographical events, and tested some general biogeographical and phylogeographical hypotheses. We found out that the genus originated in Australia 20-15 million years ago and colonized New Guinea twice, approximately 10-5 million years ago. However, only one of the colonization events was very successful resulting in a radiation of more than 150 species. We also showed that the main reason for this amazing species diversity is the geological evolution of the island. New Guinea, with its intensive volcanic activity, rapid rising of new masses, and other complex geological processes, was a cradle of biodiversity for the genus providing a species richness and establishing a high local endemism that is not older than the present-day landmass. The results of our study brought the knowledge on the genus to a completely new level and influenced general fields of science. They, especially identification tables and distributional maps, can be widely used in ecological research and for nature conservation purposes. Our results are essential for any scientific discipline dealing with biological objects and which uses species names as labels for organisms illustrating their practical importance. For that, we increased availability of our data not only by publishing them traditionally in scientific papers, but also by disseminating species descriptions, illustrations, maps, digital images through cybersources. These data are aiming not only at professional entomologists but also at all who are interested in nature. We also think that information about our research will stimulate other entomologists to study the insect fauna of New Guinea, as well as arouse interest of common people in nature examination and conservation.