The magnitude of global marine species diversity.

BACKGROUND: The question of how many marine species exist is important because it provides a metric for how much we do and do not know about life in the oceans. We have compiled the first register of the marine species of the world and used this baseline to estimate how many more species, partitioned among all major eukaryotic groups, may be discovered. RESULTS: There are ∼226,000 eukaryotic marine species described. More species were described in the past decade (∼20,000) than in any previous one. The number of authors describing new species has been increasing at a faster rate than the number of new species described in the past six decades. We report that there are ∼170,000 synonyms, that 58,000-72,000 species are collected but not yet described, and that 482,000-741,000 more species have yet to be sampled. Molecular methods may add tens of thousands of cryptic species. Thus, there may be 0.7-1.0 million marine species. Past rates of description of new species indicate there may be 0.5 ± 0.2 million marine species. On average 37% (median 31%) of species in over 100 recent field studies around the world might be new to science. CONCLUSIONS: Currently, between one-third and two-thirds of marine species may be undescribed, and previous estimates of there being well over one million marine species appear highly unlikely. More species than ever before are being described annually by an increasing number of authors. If the current trend continues, most species will be discovered this century.

Epibionts on the lingulate brachiopod Diandongia from the Early Cambrian Chengjiang Lagerstatte, South China.

The classic Chengjiang Lagerstätte (Lower Cambrian, Atdabanian stage: Yu'anshan Formation) Yunnan, southwestern China, has yielded, besides the exceptional and often controversial soft-bodied fossils, a fauna of primitive/early lingulid brachiopods. Diandongia pista (Rong 1974) is one of the commonest and most strongly mineralized of the phosphatic brachiopods from the Lagerstätte. The shells of this species have been found to commonly serve as a basibiont host. Epibionts comprise the coeval brachiopod Longtancunella chengjiangensis and the cone-shaped cnidarian-related Archotuba conoidalis, as well as rounded smaller-sized epizoans (lesser than 2 mm). A principle morphological analysis demonstrates that the ovoid and rounded organisms that often occur along the commissure of D. pista resemble small juvenile or immature brachiopods. Epibiont-bearing shells of D. pista with soft-tissue preservation demonstrate that the host brachiopods were overgrown while alive, and provide an argument for D. pista having a semi-infaunal life style with only the slim pedicle embedded in sediment. The epibiotic association sheds direct light on the ecology of Cambrian brachiopods in soft-substrate marine environments. The Chengjiang fossils demonstrate that the Early Cambrian brachiopods, as compared with recent lingulids, occupied different and a wider spectrum of ecological niches and tiers of space.

Evidence of lophophore diversity in early Cambrian brachiopoda.

The lophophore, an essential organ of the Brachiopoda, has been used widely in evolutionary and advanced phylogenetic studies, but is hitherto unknown in the fossil record. Here, the extraordinarily well-preserved lophophores of two inarticulated brachiopods Lingulella chengjiangensis and Heliomedusa orienta, from the Lower Cambrian Chengjiang fauna (Yunnan, China) are described. These primitive lophophores, respectively, trocholophous and schizolophous, have some key characters that may be plesiomorphies inherited by their recent descendants. This discovery provides direct evidence regarding the taxonomy, ecosystems and early evolution of inarticulated brachiopods.

[Regenerating histogenesis in Phoronida]. / L'histogenèse régénératrice chez les phoronidiens.

The regeneration (organogenesis was studied by Emig, 1972 a, b) of Phoronida can be divided into three phases: the first one, cicatrisation, is characterized by a provisional mesodermal scar-tissue, later the old epidermis cover this scar-tissue. The regenerating blastema, second phase, takes place by cellular dedifferentiation processes; each germ layer (ectoderm, mesoderm, endoderm) regenerates itself from its own elements. One exception only seems to be oesophagel regeneration by "metaplasia" of the prestomacal cells during the asexual reproduction. The differentiation of the amputated structures (third phase) appears submitted to the inductive influence of the mesoderm and to the trophic action of the nervous system (especially the epithelial plexus). The polarity in regeneration sets a problem in Phoronida.