Taxonomic revision of the Mediterranean Plakina Schulze (Porifera, Demospongiae, Homoscleromorpha)

Only three species of the sponge genus Plakina Schulze have been described from the Mediterranean since 1880, in spite of a large amount of allegedly intraspecific variability in morphological characters. However, recent genetic studies based on electrophoretic techniques have revealed extensive cryptic speciation in north-western Mediterranean Plakina , demonstrating that most of this variation was interspecific rather than intraspecific. We describe in detail the morphology and anatomy of four new species of Plakina from the Mediterranean– P. crypta, P. weinbergi, P. endoumensis and P. jani –of which the latter two were discovered through allozyme electrophoresis. Plakina monolopha Schulze and P. trilopha Schulze are redescribed, and their morphological and geographical limits are discussed along with those of P. dilopha Schulze. Accurate analysis of the internal anatomy and of the shape and ramification pattern of lophose spicules in scanning electron microscopy provides new, powerful morphological criteria for species discrimination in Plakina. More widespread use of such new taxonomic characters should provide evidence against the alleged cosmopolitanism of some Plakina species, thus generating an increase in estimates of the biodiversity of plakinids.     

Cryptic speciation and phylogeographic relationships in the elephant ear sponge Ianthella basta (Porifera,Ianthellidae) from northern Australia

Morphological delineation of sponge species is hindered by the narrow range of fixed diagnostic characters and our limited knowledge of how much phenotypic plasticity the sponge body plan assumes in response to environmental conditions. Here, we make use of the partial mitochondrial cytochrome c oxidase subunit I (COI) gene and the second internal transcribed spacer (ITS2) region to assess the taxonomic validity of colour morphotypes observed in the elephant ear sponge Ianthella basta (Pallas, 1776) across its distribution range in northern Australia, and explore levels and patterns of genetic diversity among populations of the species collected from both sides of the Torres Strait. Molecular phylogenetic analyses revealed congruent topologies consistent with three evolutionarily significant units (ESUs) that were independent of the morphology of the sponge. ESU I includes previously morphologically and genetically delineated western Pacific specimens of I. basta (Guam), and probably corresponds to the type specimen originally described from Indonesia. ESU I occurs in almost all sampling sites across northern Australia, suggesting considerable levels of connectivity among reefs throughout the Torres Strait. ESUs II and III are each exclusively associated with a geographic region of high sponge species richness separated by Torres Strait, and probably represent the result of historical population fragmentation. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 225–235.     

The histidine kinase CpHK2 has impact on spore germination, oxidative stress and fungicide resistance, and virulence of the ergot fungus Claviceps purpurea

Histidine kinases are important mediators for adaptation of bacteria and plants to environmental signals. Genome analyses of filamentous fungi have revealed the presence of a high number of potential hybrid histidine kinase (HK)-encoding genes; the role of most of these potential sensors is so far unclear, though some members of the class III histidine kinases were shown to be involved in osmostress responses. Here we present a functional analysis of cphk2 , a histidine kinase-encoding gene in the biotrophic grass pathogen Claviceps purpurea . The putative product of cphk2 (CpHK2) was shown to group within family X of fungal HKs and it had high homology to the oxidative stress sensors SpMAK2/3 of Schizosaccharomyces pombe . Analysis of a cphk2 deletion mutant indicated that this histidine kinase is involved in spore germination, sensitivity to oxidative stress and fungicide resistance. In addition, virulence of the D cphk2 mutant on rye was significantly reduced compared with the wild-type strain, even if the conidial titre was adjusted to the lower germination rate. This is the first report of a role for a class X histidine kinase in a filamentous fungus.     

Swimming medusoid gonophores in two species of Sertularella (Cnidaria,Hydrozoa, Sertulariidae) from Réunion Island,Indian Ocean

Summary

Two life cycle patterns predominate in thecate hydroids, those with alternating polyp and medusa stages, and those with fixed gonophores. Relatively few species release short-lived medusoids, also called swimming gonophores, that carry the gametes. In the family Sertulariidae, with its large number of taxa, this mode of metagenesis has been documented previously for only two species. It is described here for two others, Sertularella diaphana (Allman, 1885) and Sertularella n. sp., from the coastal waters of Reunion Island. Freshly collected fertile male and female colonies released medusoids near dawn, one per gonotheca. Strong contractions of the bell in the swimming movements induced the shedding of gametes. Once gametes were shed, medusoids quickly degenerated and died. The medusoids were similar morphologically in these two related species, and no obvious sexual dimorphism was noted. They were ovoid in shape, the spadix was eccentric, and a velum was present; but they lacked a mouth, tentacles, sense organs, and radial and circular canals as described earlier in Amphisbetia operculata (Linneus, 1758) and Sertularia marginata Kirchenpauer, 1864. However, the medusoids described here lacked exumbrellar nematocysts. Moreover, the spadix with its dense mass of gametes was different from all other described in being stuck from base to top on one side of the subumbrella in spite of hanging freely in the subumbrellar cavity. The hypothesis that this unusual reproductive mode in sertulariids has been underestimated is confirmed by these findings.     

A molecular phylogeny of the checkered beetles and a description of Epiclininae a new subfamily (Coleoptera: Cleroidea: Cleridae)

We provide the first molecular phylogeny of the clerid lineage (Coleoptera: Cleridae, Thanerocleridae) within the superfamily Cleroidea to examine the two most recently proposed hypotheses of higher level classification. Phylogenetic relationships of checkered beetles were inferred from approximately ～5000 nt of both nuclear and mitochondrial rDNA (28S, 16S and 12S) and the mitochondrial protein‐coding gene COI. A worldwide sample of ～70 genera representing almost a quarter of generic diversity of the clerid lineage was included and phylogenies were reconstructed using Bayesian and Maximum Likelihood approaches. Results support the monophyly of many proposed subfamilies but were not entirely congruent with either current classification system. The subfamilial relationships within the Cleridae are resolved with support for three main lineages. Tillinae are supported as the sister group to all other subfamilies within the Cleridae, whereas Thaneroclerinae, Korynetinae and a new subfamily formally described here, Epiclininae subf.n ., form a sister group to Clerinae + Hydnocerinae.     

Relationship between starch degradation and carbon demand for maintenance and growth in Arabidopsis thaliana in different irradiance and temperature regimes

Experiments were designed to compare the relationship between starch degradation and the use of carbon for maintenance and growth in Arabidopsis in source‐limited and sink‐limited conditions. It is known that starch degradation is regulated by the clock in source‐limited plants, which degrade their starch in a linear manner such that it is almost but not completely exhausted at dawn. We asked whether this response is maintained under an extreme carbon deficit. Arabidopsis was subjected to a sudden combination of a day of low irradiance, to decrease starch at dusk, and a warm night. Starch was degraded in a linear manner through the night, even though the plants became acutely carbon starved. We conclude that starch degradation is not increased to meet demand in carbon‐limited plants. This network property will allow stringent control of starch turnover in a fluctuating environment. In contrast, in sink‐limited plants, which do not completely mobilize their starch during the night, starch degradation was accelerated in warm nights to meet the increased demand for maintenance and growth. Across all conditions, the rate of growth at night depends on the rate of starch degradation, whereas the rate of maintenance respiration decreases only when starch degradation is very slow.     

Trophic ecology of adult male Odonata. II. Dietary contributions of aquatic food sources

1. Insects that emerge from rivers provide nutritional subsidies to local riparian predators. Adult damselflies and dragonflies often benefit from aquatic resources, but their high mobility and evasiveness have made it difficult to monitor their diets. 2. A dual fatty acid and stable isotope analysis approach was used to investigate the links between Odonata size and behaviour with proportions of their aquatically derived nutritional sources. Additionally, the study investigated the variation in dietary contributions of aquatic food sources to Odonata between two sections of a river, each with different aquatic productivity rates. 3. Variations in body size and foraging method of Odonata in the Kowie River (South Africa) contributed to differences in the contributions of aquatic food sources to their diets. Large Odonata that consumed prey in flight had smaller proportions of aquatic indicator fatty acids and stable isotope‐generated proportions of aquatic food sources than did the smaller Odonata that consumed prey from perches. 4. There was a considerable amount of interspecific variation in indicators of aquatic feeding, but Odonata at an upstream site had smaller proportions of aquatic indicators than those at a downstream site which had higher insect emergence rates. 5. The findings of this study contribute information on the dynamics of feeding ecology among adult Odonata, and the substantial contributions of aquatic prey (>80% of total diet in some cases) indicated that cross‐boundary trophic linkages via odonates are strong in the Kowie River.