Systematics and distribution of decapod crustaceans associated with late Eocene coral buildups from the southern Pyrenees (Spain)

A new decapod crustacean assemblage associated with late Eocene coral reef deposits in northeast Spain (southern Pyrenees) is recorded; it includes Gemmellarocarcinus riglosensis sp. nov., Daira corallina sp. nov., Lobogalenopsis joei sp. nov., Liopsalis cf. anodon (Bittner, 1875) and Galenopsis crassifrons A. Milne- Edwards, 1865. The genera Gemmellarocarcinus, Daira and Lobogalenopsis are here recorded for the first time from Eocene strata of the Iberian Peninsula, extending their palaeobiogeographical distribution. Detailed sampling from three different coral reef facies within the La Peña buildup, here referred to as branching, tabular and massive, suggest that the core of the reef, which was dominated by branching corals, hosted the highest diversity and abundance of decapod crustaceans. Daira corallina sp. nov. predominated in the branching corals facies, while G. crassiforns was the most abundant taxon within the tabular coral facies and carpiliids showed preferences for environments with massive corals. Thus, this constitutes a good example of primary ecological zonation among decapod crustaceans within a discrete reef.

Longitudinal ecological zonation in four Algerian streams

This hydro-biological survey on benthic invertebrates was carried out in the most important hydrographic network of the Mitidja plain,Oued El Harrachbasin, Algeria. Results revealedecological zonation taking into account the taxonomic richness and the relative abundance of different zoological groups, and allowed distinguishing abundant, ubiquitous and permanent taxa as well as the existence of a spatiotemporal faunistic gradient. These preliminary results allowed highlightingtaxonomically the “upstream invertebrate fauna”, the “ubiquitous invertebrate fauna” and the “downstream invertebrate fauna”. Consequently, it appearedthat Plecoptera, Hemiptera, Coleoptera are characteristic to the upstream area during the whole year in most of the sampling sites, whereas Diptera, Oligochaeta and Hydracarina are more abundant in the downstream area but in less density in the middle stream. On the other hand, the longitudinal evolution approach was considered in order to evaluate the inter-site distribution. According to the trophic levels, the classification between the various communities was investigated taking into account the concepts of the "Food Functional Group" and "The River Continuum Concept".