The Juan Fernández diving beetle, Anisomeria Bistriata (Brullé 1835): habitats, communities and conservation

El archipiélago de Juan Fernández se sitúa en el océano Pacífico, aproximadamente a 600 km de la costa de Chile. Se ha sugerido que de no revertirse la degradación ambiental, la biota de estas islas pronto se verá severamente amenazada. Solamente se conocen tres especies de escarabajos buceadores (Dytiscidae) en Juan Fernández: Anisomeria bistriata (Brullé, 1835), la especie más notable dada su morfología particular, Rhantus signatus kuscheli Guignot, 1952, ambas endémicas de la isla Robinson Crusoe, y Lancetes backstromi Zimmermann, 1924, endémica de la isla Alejandro Selkirk. Con el fin de estudiar la abundancia y los hábitats de A. bistriata y R. s. kuscheli, hemos visitado la isla Robinson Crusoe. Los muestreos comprendieron pequeños esteros y algunos contenedores artificiales. Anisomeria bistriata fue recolectada en Bahía Cumberland y Plazoleta El Yunque, a altitudes de 80- 235 msnm, principalmente en contenedores artificiales, lo que posiblemente indique cierta afinidad por los hábitats lénticos. Hacia fines del verano, aproximadamente 95% de las larvas estaban en el tercer estadio, lo que podría indicar una marcada estacionalidad en el ciclo de vida de esta especie. Rhantus signatus kuscheli fue recolectado en Bahía Cumberland y Puerto Francés, a altitudes de 34-99 msnm. Contrariamente a A. bistriata, fue más frecuente en los esteros. Las larvas (la mayoría de primer estadio) fueron capturadas en el mismo estero que los adultos, en los sectores más vegetados. A pesar de la considerable degradación ambiental que ha sufrido la isla Robinson Crusoe, ambas especies no parecen severamente amenazadas.The Juan Fernández archipelago is situated in the Pacifi c Ocean, about 600 km of the coast of Chile. It has been suggested that if environmental degradation is not reversed, the biota of these islands will soon be severely threatened. Only three species of diving beetles (Dytiscidae) are known from Juan Fernández: Anisomeria bistriata (Brullé, 1835), the most remarkable species given its particular morphology, Rhantus signatus kuscheli Guignot, 1952, both endemic to Robinson Crusoe island, and Lancetes backstromi Zimmermann, 1924, endemic to Alejandro Selkirk island. In order to study the abundance and habitats of A. bistriata and R. s. kuscheli, we visited Robinson Crusoe Island. The samplings involved small creeks and some artifi cial containers. Anisomeria bistriata was collected in Bahía Cumberland and Plazoleta El Yunque, at altitudes 80-235 m asl, mainly in artifi cial containers, maybe refl ecting certain affi nity for lentic habitats. By late summer, about 95% of the larvae were third instars, which would argue in favour of a marked seasonality in the life cycle of the species. Rhantus signatus kuscheli was collected in Bahía Cumberland and Puerto Francés, at altitudes 34-99 m asl. Contrary to A. bistriata, it was more frequent in creeks. The larvae (most of them fi rst instars) were captured in the same creek as the adults, in the most vegetated portions. Despite the signifi cant environmental degradation than Robinson Crusoe island has supported, both species do not seem severely threatened.Fil: Michat, Mariano Cruz. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental. Laboratorio de Entomologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Balke, Michael. Ludwig Maximilians Universitat; Alemania. Zoologische Staatssammlung München; Alemani

Description of two new species of the Exocelina broschii-group from Papua New Guinea, with revision and key to all representatives of this species group (Coleoptera, Dytiscidae, Copelatinae)

Two new species of Exocelina Broun, 1886 from Papua New Guinea are described herein: E. mondmillensis sp. n. and E. pseudomarinae sp. n. They are placed into the E. broschii-group based on the shovel/fork-like ventral sclerites of their median lobe. While the former has rather distinct combination of the morphological characters (inconspicuous dorsal punctation, thin apex of the median lobe and ventral sclerite of the median lobe with two tips of different length), the latter is very similar to already described species E. marinae (Shaverdo, Sagata & Balke, 2005). All described species of the group are revised and a key to their identification is provided. Important diagnostic characters (habitus, color, protarsomeres 4-5, median lobes, and parameres) are illustrated. Data on the distribution of all species of the group are given showing that its representatives occur only in Papua New Guinea and most of them are widely distributed in it central part

A new, widely distributed species of the Exocelina ekari-group from West Papua (Coleoptera, Dytiscidae, Copelatinae)

Exocelina manokwariensis sp. n. from West Papua is placed into the E. ekari-group based on the structure of its male genitalia. The new species is described, including its three subspecies, from the mainland of West Papua, Waigeo Island, Batanta and Salawati Islands, and Bomberai peninsula. An identification key to the subspecies as well as data on species distribution are provided

Taxonomic revision of New Guinea diving beetles of the Exocelina danae group, with the description of ten new species (Coleoptera, Dytiscidae, Copelatinae)

Ten new species of Exocelina Broun, 1886 from New Guinea are described: E. andakombensis sp. n., E. garaina sp. n., E. injiensis sp. n., E. kabwumensis sp. n., E. marawaga sp. n., E. posmani sp. n., E. tekadu sp. n., E. varirata sp. n., E. wareaga sp. n., and E. woitapensis sp. n. All of them together with five already described species are united into the newly defined E. danae-group (with E. miriae-subgroup), a polyphyletic complex of related species with lateral setation on the median lobe. In the light of newly available material, all previously described species of the E. rivulus-group are considered to belong to a single species, E. damantiensis (Balke, 1998), which is now placed into the E. danae-group, and three new synonyms are therefore proposed: E. madangensis (Balke, 2001) syn. n., E. patepensis (Balke, 1998) syn. n., and E. rivulus (Balke, 1998) syn. n. Exocelina tarmluensis (Balke, 1998) syn. n. is a junior synonym of E. danae (Balke, 1998). Redescription of E. atratus (Balfour-Browne, 1939) is provided based on its type material. An identification key to all known species of the group is provided, and important diagnostic characters are illustrated. Data on the species distribution are given, showing that whilst most species are local endemics, E. damantiensis is extremely widely distributed

A Molecular phylogeny of Alpine subterranean <i>Trechini</i> (Coleoptera: Carabidae)

Background: The Alpine region harbours one of the most diverse subterranean faunas in the world, with many species showing extreme morphological modifications. The ground beetles of tribe Trechini (Coleoptera, Carabidae) are among the best studied and widespread groups with abundance of troglobionts, but their origin and evolution is largely unknown. Results: We sequenced 3.4 Kb of mitochondrial (cox1, rrnL, trnL, nad1) and nuclear (SSU, LSU) genes of 207 specimens of 173 mostly Alpine species, including examples of all subterranean genera but two plus a representation of epigean taxa. We applied Bayesian methods and maximum likelihood to reconstruct the topology and to estimate divergence times using a priori rates obtained for a related ground beetle genus. We found three main clades of late Eocene-early Oligocene origin: (1) the genus Doderotrechus and relatives; (2) the genus Trechus sensu lato, with most anisotopic subterranean genera, including the Pyrenean lineage and taxa from the Dinaric Alps; and (3) the genus Duvalius sensu lato, diversifying during the late Miocene and including all subterranean isotopic taxa. Most of the subterranean genera had an independent origin and were related to epigean taxa of the same geographical area, but there were three large monophyletic clades of exclusively subterranean species: the Pyrenean lineage, a lineage including subterranean taxa from the eastern Alps and the Dinarides, and the genus Anophthalmus from the northeastern Alps. Many lineages have developed similar phenotypes independently, showing extensive morphological convergence or parallelism. Conclusions: The Alpine Trechini do not form a homogeneous fauna, in contrast with the Pyrenees, and show a complex scenario of multiple colonisations of the subterranean environment at different geological periods and through different processes. Examples go from populations of an epigean widespread species going underground with little morphological modifications to ancient, geographically widespread lineages of exclusively subterranean species likely to have diversified once fully adapted to the subterranean environment

Experimental salt marsh islands: a model system for novel metacommunity experiments

Shallow tidal coasts are characterised by shifting tidal flats and emerging or eroding islands above the high tide line. Salt marsh vegetation colonising new habitats distant from existing marshes are an ideal model to investigate metacommunity theory. We installed a set of 12 experimental salt marsh islands made from metal cages on a tidal flat in the German Wadden Sea to study the assembly of salt marsh communities in a metacommunity context. Experimental plots at the same elevation were established within the adjacent salt marsh on the island of Spiekeroog. For both, experimental islands and salt marsh enclosed plots, the same three elevational levels were realised while creating bare patches open for colonisation and vegetated patches with a defined transplanted community. One year into the experiment, the bare islands were colonised by plant species with high fecundity although with a lower frequency compared to the salt marsh enclosed bare plots. Initial plant community variations due to species sorting along the inundation gradient were evident in the transplanted vegetation. Competitive exclusion was not observed and is only expected to unfold in the coming years. Our study highlights that spatially and temporally explicit metacommunity dynamics should be considered in salt marsh plant community assembly and disassembly

A new species of Agaporomorphus Zimmermann, 1921 from Peru (Coleoptera, Dytiscidae, Copelatinae)

Agaporomorphus julianeae sp. n. is described from the Biological Field Station Panguana, in Huanuco province of central Peru. The new species belongs to the A. knischi-group sensu Miller 2005. Together with A. knischi Zimmermann, 1921 and A. colberti Miller & Wheeler, 2008 this is the third species of the genus with broadly enlarged male antennomeres. The new species can be separated from A. colberti and A. knischi by the smaller please expanded male antennomere VIII, and the form of the median lobe. Important species characters (median lobe, male antennae, metafemur, colour pattern) of the new species and A. knischi are figured, and the habitat, a temporary blackwater forest pond, and its species rich water beetle coenosis are illustrated and described in detail. The Brazilian A. mecolobus Miller, 2001, only known from the type material from Sao Paulo, is here recorded for Minas Gerais. Habitus photos of four additional Agaporomorphus species and Hydrodytes opalinus (Zimmermann, 1921) are provided. Altogether ten species of Agaporomorphus are now known

Mosaic patterns of diversification dynamics following the colonization of Melanesian islands

The fate of newly settled dispersers on freshly colonized oceanic islands is a central theme of island biogeography. The emergence of increasingly sophisticated methods of macroevolutionary pattern inference paves the way for a deeper understanding of the mechanisms governing these diversification patterns on lineages following their colonization of oceanic islands. Here we infer a comprehensive molecular phylogeny for Melanesian Exocelina diving beetles. Recent methods in historical biogeography and diversification rate inference were then used to investigate the evolution of these insects in space and time. An Australian origin in the mid-Miocene was followed by independent colonization events towards New Guinea and New Caledonia in the late Miocene. One colonization of New Guinea led to a large radiation of >150 species and 3 independent colonizations of New Caledonia gave rise to about 40 species. The comparably late colonizations of Vanuatu, Hawaii and China left only one or two species in each region. The contrasting diversification trajectories of these insects on Melanesian islands are likely accounted for by island size, age and availability of ecological opportunities during the colonization stage

Description of 23 new species of the Exocelina ekari-group from New Guinea, with a key to all representatives of the group (Coleoptera, Dytiscidae, Copelatinae)

Twenty three new species of Exocelina Broun, 1886 from New Guinea are described herein: E. bewaniensis sp. n.,E. bismarckensis sp. n.,E. craterensis sp. n.,E. gorokaensis sp. n.,E. herowana sp. n.,E. jimiensis sp. n.,E. kisli sp. n.,E. ksionseki sp. n.,E. lembena sp. n.,E. mantembu sp. n.,E. michaelensis sp. n.,E. pinocchio sp. n.,E. pseudoastrophallus sp. n.,E. pseudobifida sp. n.,E. pseudoedeltraudae sp. n.,E. pseudoeme sp. n.,E. sandaunensis sp. n.,E. simbaiarea sp. n.,E. skalei sp. n.,E. tabubilensis sp. n.,E. tariensis sp. n.,E. vovai sp. n.,and E. wannangensis sp. n. All of them have been found to belong to the E. ekari-group. An identification key to all known species of the group is provided, and important diagnostic characters (habitus, color, male antennae, protarsomeres 4-5, median lobes, and parameres) are illustrated. Data on the distribution of the new species and some already described species are given