The late Cenozoic Thiaridae (Mollusca, Gastropoda, Cerithioidea) of the Albertine Rift Valley (Uganda-Congo) and their bearing on the origin and evolution of the Tanganyikan thalassoid malacofauna

The recent cerithioid malacofauna of meromictic Lake Tanganyika is unique in its degree of thalassoid convergence with marine molluscs. This is generally considered the result of a long-lasting intensive escalation and cladogenesis caused by a coevolutionary prey–predator interaction in a freshwater ecosystem with sea-like characteristics, i.e. exceptional longevity (ca. 7–12 Ma) and vast dimensions (present surface area: 32900 km², present maximum depth: 1470 m). In the Albertine Basin, ca 300 km north of the Tanganyika Trough, Palaeolake Obweruka existed during Mio-Pliocene times. In many aspects, it can be considered as a 'sister lake' of Lake Tanganyika, being also long-lived (from ca 7.5 to 2.5 Ma), extensive (surface: 27000 km²) and meromictic. Like Lake Tanganyika it belonged to the Congo catchment. Although thalassoid molluscs have been known from the Albertine deposits since the beginning of the 20th Century, previous researchers recognised only four polymorphic thiarid species, two of which were thalassoid. Detailed in situ collecting shows that the perceived low species diversity and high variability of the Obwerukan thalassoids is a phenomenon of the museum drawer. In the field the thiarid species and other molluscs are not extremely polymorphic, as formerly thought, but tend to occur in discrete morphometric packages according to stratigraphic level and geographic area. The species richness of the Palaeolake Obweruka thiarids has thus been severely underestimated, as is also the case for the Recent Tanganyikan thiarids. The present authors discern 35 species and 7 genera in the Albertine deposits (2 of which are new to science), and consider this to be a conservative estimate. In their degree of diversification and morphological escalation, the Obwerukan thiarids are thus comparable to the Tanganyika thalassoids. Arguments are presented that the thalassoids of these lakes are polyphyletic, that they are derived from the same genera (mainly Potadoma, Potadomoides and Pseudocleopatra) and that the tempo and mode of their intralacustrine evolution must have been largely similar. As for the tempo of evolution, the Albertine fossil record shows that escalation in shell morphology and ornamentation in the Thiaridae was extremely rapid, as in the Ampullariidae and Viviparidae (Van Damme & Pickford, 1995, 1999). In the Thiaridae heavily ornate shells evolved from an unornamented ancestor in two consecutive bursts, each lasting less than 0.1 million years over a total period of ca. 1 million years. The punctuated escalation in the thiarids was initiated millions of years after the lake was formed. This implies that the degree of escalation is not related to age of a lake and that the Tanganyikan thalassoids or part of them may not be particularly old, even though Lake Tanganyika itself is. As to the mode of evolution, it appears that escalation is a coevolutionary reaction to predation but that this selective pressure only triggers a reaction under specific conditions and in synergy with other environmental factors. The Obwerukan thiarid fossil record also indicates that iterative evolution of molluscan shells may be of frequent occurrence. What is considered to be a single polymorphic chronospecies, static over a great length of time, may actually be a sequence of several species that branched at different moments from the same ancestral phenotype. Finally, there is the inference that bottle-necking may be, geologically speaking, so common that it forms an essential force in macroevolution.     

A new genus and species of monostiliferoidean nemertean (Nemertea: Enopla) found on an egg mass of the anomuran decapod Paralithodes camtschatica

A new genus and species of monostiliferoidean enoplan nemertean from Alaska is described and illustrated. The nemertean, Alaxinus oclairi gen. et sp. nov. , was found on the egg mass of a red king crab, Paralithodes camtschatica.     

A new Carboniferous bivalve from Gondwana

The dawning of the Late Palaeozoic glaciations affected faunas of Gondwana and induced endemism. Deposits of that epoch occur in Argentina and Australia, and they yield the oldest record of some endemic taxa. The new bivalve genusAmosius n. gen. described here comes from the lower strata of theLevipustula levis Zone (Serpukhovian) of central Patagonia, where it is associated with the oldest Carboniferous glacial deposits.      

A new Permian gnetalean cone as fossil evidence for supporting current molecular phylogeny

• Background and aims The order Gnetales has been the central focus of controversy in seed plant phylogeny. Traditional treatment of morphology supports the anthophyte hypothesis with Gnetales sister to angiosperms but current molecular data reject this hypothesis. A new fossil gnetalean cone, Palaeognetaleana auspicia gen. et sp. nov., is reported from the Upper Permian in North China, and its phylogenic implications are considered.• Methods Samples of cones from the upper part of the Upper Permian redbeds of Baode section, northwestern Shanxi Province, China, were examined.• Key results The cone is characterized by its unusual nature of reproduction that combines features of post-Triassic gnetaleans and some of the Palaeozoic conifers. It is made up of a number of imbricate axillary units, each simply formed by an ovule and a subtending bract, which may be comparable with the axillary seed-scale complex of some of the Palaeozoic conifer cones. The cone exhibits at least a partially bisexual character that appears to have pollen sacs with monosulcate ribbed pollen grains and sessile, asymmetric, and radiospermic ovules. The ovule has an integument of three envelopes: an outer one of pointed scales; a middle sclerified one; and an inner cuticle that extends upward into a micropyle with an oblique tip.• Conclusions The new Permian cone has unequivocal affinity with the Gnetales. The fossil has considerably extended the divergence time of the Gnetales from 140 (210?) back to 270 myr ago and, therefore, provides the first significant fossil evidence to support the current conclusion based on molecular data of seed plants, i.e. monophyletic gymnosperms, comprising the Gnetales are closely related to conifers.Key words: Palaeognetaleana auspicia (gen. et sp. nov.), Gnetales, bisexual fossil cone, phylogeny of seed plants, radiation of gymnosperms, molecular data, Late Permian, North China     

Sensitization of T cells to apoptosis—A role for ROS?

T cell homeostasis is achieved by balancing the production and proliferation of T cells with their apoptotic cell death. Activation of naïve T cells by antigen in the context of MHC results in the massive expansion of antigen-specific T cells and the production of reactive oxygen species (ROS). Following expansion, the majority of the T cells die via apoptosis, while a small number of them survive and differentiate into memory T cells. This cell fate decision is crucial to our understanding of how autoimmunity is avoided and how immunity is maintained. It has become increasingly clear that ROS can affect this cell fate decision by sensitizing T cells to apoptosis. Interestingly, ROS have effects on both intrinsic and extrinsic apoptosis pathways through modulation of expression of the major molecules in these pathways, Bcl-2 and FasL. In this review, we will focus on the pro-apoptotic effects of ROS and mechanisms by which they regulate the death of T cells.     

Phylogenic and phenotypic characterization of some Eubacterium-like isolates from human feces: description of Solobacterium moorei Gen. Nov., Sp. Nov

Three isolated strains from human feces were characterized by biochemical tests and 16S rDNA analysis. Phylogenetic analysis revealed that these isolated strains were members of the Clostridium subphylum of gram-positive bacteria. The phenotypic characters resembled those of the genus Eubacterium, but these strains were shown to be phylogenetically distant from the type species of the genus, Eubacterium limosum. The strains showed a specific phylogenetic association with Holdemania filiformis and Erysipelothrix rhusiopathiae. Based on a 16S rDNA sequence divergence of greater than 12% with H. filiformis and E. rhusiopathiae, a new genus, Solobacterium, is proposed for three strains, with one species, Solobacterium moorei. The type strain of Solobacterium moorei is JCM 10645T.     

Charipinae (Hymenoptera: Figitidae) from Australia: revision of the genus Thoreauana Girault, 1930 and description of Dilapothor n. gen.

Abstract  The Australian genus Thoreauana Girault is revised: the three known species are redescribed and Thoreauana giraulti sp. n. is described. A new genus of Charipinae from Australia, Dilapothor n. gen., is described. The diagnostic characters for the tribe Charipini are discussed and a key to the Charipini genera is provided.     

PROPOSAL OF THE EUPTILOTEAE HOMMERSAND ET FREDERICQ,TRIB. NOV. AND TRANSFER OF SOME SOUTHERN HEMISPHERE PTILOTEAE TO THE CALLITHAMNIEAE (CERAMIACEAE,RHODOPHYTA)1

Morphological and molecular studies demonstrate that the tribe Ptiloteae (Ceramiaceae, Ceramiales) is polyphyletic. The Ptiloteae, sensu stricto, occur only in the Northern Hemisphere and all Southern Hemisphere representatives belong in other tribes. Three genera (Euptilota, Seirospora, and Sciurothamnion) are transferred to the Euptiloteae Hommersand et Fredericq, trib. nov., and the Callithamnieae is revised to include three Ptilota‐like genera, Georgiella, Falklandiella, and Diapse, and two new genera. Heteroptilon Hommersand, gen. nov. is erected to receive Euptilota pappeana Kützing 1849 and Aglaothamnion rigidulum De Clerck, Bolton, Anderson et Coppejans 2004 from South Africa, and Aristoptilon Hommersand et W. A. Nelson, gen. nov. is established to receive Euptilota mooreana Lindauer 1949 from New Zealand. The principal difference between the Euptiloteae and the Callithamnieae is seen in the earliest stages after fertilization. The fertilized carpogonium enlarges and forms a pair of tube‐like protuberances directed toward the auxiliary cells that are cut off as connecting cells in the Euptiloteae, whereas in the Callithamnieae the carpogonium usually divides into two cells, each of which cuts off a small connecting cell that fuses with an adjacent enlarging auxiliary cell. Nuclei are terminal in spermatangia of the Euptiloteae, subtended by mucilaginous vesicles, and are medial in the Callithamnieae situated between apical and basal vesicles. The Euptiloteae and Callithamnieae (including the Ptilota‐like members) are each strongly supported in maximum‐likelihood tree topologies resulting from analyses of combined 18S rDNA, 28S rDNA, 16S rDNA, and rbcL data sets. Their sister relationship is also well supported.     

PHYLOGENY OF THE HYDRODICTYACEAE (CHLOROPHYCEAE): INFERENCES FROM rDNA DATA1

The hydrodictyacean green algal lineage has been the focus of much research due to the fossil record of at least some members, their ornamented cell walls, and their distinctive reproductive strategies. The phylogeny of the family was, until recently, exclusively morphology based. This investigation examines hydrodictyacean isolates from several culture collections, focusing on sequences from ribosomal data: 18S rDNA, 26S rDNA (partial), and internal transcribed spacer (ITS)‐2 data. Results from phylogenetic analyses of independent and combined data matrices support the Hydrodictyaceae as a monophyletic lineage that includes isolates of Chlorotetraedron, Hydrodictyon, Pediastrum, Sorastrum, and Tetraedron. Phylogenetic analyses of rDNA data indicate that the three‐dimensional coenobium of Hydrodictyon is evolutionarily distinct from the three‐dimensional coenobium of Sorastrum. The more robust aspects of the ITS‐2 data corroborate the 18S+26S rDNA topology and provide a structural autapomorphy for the Hydrodictyaceae and Neochloridaceae, that is, an abridgment of helix IV in the secondary structure. The rDNA data do not support monophyly of Pediastrum but rather suggest the existence of four additional hydrodictyacean genera: Monactinus, Parapediastrum, Pseudopediastrum, and Stauridium.     

Two new genera and twelve new species of Anthuridea (Crustacea: Isopoda) from off the West Coast of New Zealand

Abstract

From the shelf and upper slope off the West Coast of the South Island of New Zealand, the following new taxa of Isopoda Anthuridea (Crustacea) are described: Kupellonura proberti n. sp. (Hyssuridae); Quantanthura pacifica n. sp., Haliophasma platytelson n. sp. and H. novaezelandiae n. sp. (Anthuridae) Albanthura stenodactyla n. gen. et sp., A. rotunduropus n. sp., Bullowanthura crebrui n. sp., Leptanthura tmncatitelson n. sp., L. exilis n. sp., L. profundicola n. sp., Paranthura longa n. sp., and Psittanthura egregia n. gen. et sp. (Paranthuridae). Most of these are blind, unpigmented species, adapted to life in deep water. Albanthura n. gen. is blind, has a single telsonic statocyst, short flagella of the antennae, a maxilliped with 3 palpal articles, and a triangular carpus on pereopods 4 to 7. Psittanthura n. gen. is also blind, with very unusual, enlarged subchelae of pereopods 1 and 2, a large, rectangular telson with a single statocyst; the maxillipedal palp is composed of 1 large and 1 small, distal article; a mandibular palp is absent.