A revision of Afrotropical Agabus Leach (Coleoptera, Dytiscidae), and the evolution of tropicoalpine super specialists

Abstract. The thirteen species of Agabus Leach, 1817, of the Afrotropical Region are revised and classified into four species groups: the dibasic ambulator -group endemic to Ethiopia, ragazzii -group with five species in Ethiopia, raffrayi -group with five species in East and South Africa, and A.discicollis Ancey, 1882, endemic to Ethiopia, is placed in the Nearctic cordatus -group. Agabus perssoni sp.n. and Agabus galamensis sp.n. are described from the highlands of Ethiopia. Agabus ruwenzoricus Guignot, 1936, stat.n. is given specific rank. Agabus ferrugatus Régimbart, 1905, is synonymized with Agabus ragazzii Régimbart, 1887, and Agabus limbicollis Régimbart, 1905, is synonymized with Agabus raffrayi Sharp, 1882, syn.n. Lectotypes are designated for the following nominal species: Agabus discicollis Ancey, 1882, Agabus raffrayi Sharp, 1882, Agabus limbicollis Régimbart, 1905, Agabus pallidus Omer-Cooper, 1931, Agabus ruwenzoricus Guignot, 1936, Agabus sjostedti Régimbart, 1908, Agabus dytiscoides Régimbart, 1908, Agabus ragazzii Régimbart, 1887, Agabus ferrugatus Régimbart, 1905, and Gaurodytes abessinicus Zimmermann, 1928. Reconstructed phylogenies are presented for the raffrayi -and ragazzii -groups. The following adaptations to tropicoalpine habitats are suggested: (1) body and especially pronotum narrow, (2) head broad anteriorly, (3) hindwing small, and (4) hind leg long and slender. Biogeography and evolution of the studied species are discussed. Four different invasions of Holarctic lineages to the East African mountains are suggested. Recurrent periods of cold and dry climate are considered the chief driving force in the evolution of high altitude super specialists.     

Ontogenetic changes in the trochoidean (Archaeogastropoda) radula, with some phylogenetic interpretations

Radulae have been examined of juvenile specimens of 18 species belonging to the Turbinidae, the Tricoliidae. and 6 subfamilies of Trochidae. The investigations show that all species pass through profound changes, usually finishing at a size of 1.5–3 teleoconch whorls. Most species have an identical, shared morphology at a size of up to 1.5–2 teleoconch whorls, except the species of Calliostomatinac and Solariellinae. The evolutionary consequences are discussed and it is suggested that such an unspecialized starting point means a high potential for specializations and future evolution. For the taxonomist this means a reduction in the reliability of radular differences as a systematic tool.     

Conflicting demands on wetland ecosystem services: nutrient retention,biodiversity or both?

1. Wetland ecosystems may, besides having considerable economical value, increase landscape biodiversity and function as traps for nutrients from land to freshwater‐ and marine systems. As a result of these features, wetlands are nowadays often protected and restored, and many countries have even initiated wetland construction programmes. 2. In the present study, we aim at increasing the knowledge on how to improve the design of a wetland with respect to both biodiversity and nutrient retention, by analysing physical, chemical and biological features of a large set of constructed wetlands. 3. Our results show that a combination of the wetland features, namely shallow depth, large surface area and high shoreline complexity are likely to provide a high biodiversity of birds, benthic invertebrates and macrophytes and to have high nitrogen retention, whereas a small, deep wetland is likely to be more efficient in phosphorus retention, but less valuable in terms of biodiversity. 4. Hence, among the features used to design new wetlands, area, depth and shoreline complexity have fundamental, and sometimes conflicting, effects on nutrient retention and biodiversity. This means that there are, within limits, possibilities to direct the ecosystem function of a specific wetland in desired directions.     

Marginal regression analysis of a multivariate binary response

We propose the use of the mean parameter for regression analysisof a multivariate binary response. We model the associationusing dependence ratios defined in terms of the mean parameter,the components of which are the joint success probabilitiesof all orders. This permits flexible modelling of higher-orderassociations, using maximum likelihood estimation. We reanalysetwo data sets, one with variable cluster size and the othera longitudinal data set with constant cluster size.     

Long pollinia on eyes: hawk-moth pollination of Cynorkis uniflora Lindley (Orchidaceae) in Madagascar

NILSSON, L. A., RABAKONANDRIANINA, E., RAZANANAIVO, R. & RANDRIAMANINDRY, J.J., 1992. Long pollinia on eyes: hawk-moth pollination of Cynorkis uniflora Lindley (Orchidaceae) in Madagascar. The pollination biology of Cynorkis uniflora Lindley (Orchidaceae) was studied on a rocky outcrop in a fragment of montane rain forest in central Madagascar. The plant was obligately pollinated by hawk-moths. Nectar was produced in a floral spur and was accessible to hawk-moths with medium-long and long tongues. All observed visits took place during the 80 min following dusk. Floral traits and visits indicated pollination association with endemic hawk-moths of the genera Nephete and Hippotion with medium tongue length and early-evening habits. The orchid pollinia had extraordinarily long caudicles (c. 16 mm) and were carried attached to the hawk-moths' eyes, thus protruding far in front of the face of the pollinator. The ratio between components of floral female and male functions within the orchid population suggested that the much elongated operative male floral parts result from strong and progressively extreme sex-specific selection for acquiring mates via hawk-moths. By far the most frequent flower-visitors of C. uniflora at the study site were long-tongued nectar thieving hawk-moths whose relative abundance probably reflected faunal imbalance caused by the destruction of nearby moth foraging habitats through deforestation.