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Until recently all the Alburnoides populations of the Macedonia-Thessaly and Western Aegean ecoregions were considered as Alburnoides bipunctatus thessalicus Stephanidis, 1950. Here a new species of spirlin, Alburnoides economoui, is described from the Spercheios River (Fthiotida Prefecture). It is distinguished from all other congeners in Greek river basins and the Danube and Elbe drainages by the combination of the following characters: a very sharp ventral keel, scaleless or with 1–2 scales; 12½ - 14½ branched anal-fin rays; 42–47 + 1–3 pored lateral line scales; 19–25 pre-dorsal scales; snout conical, slightly pointed; snout length shorter than eye diameter; pelvic-fin origin about midway between pectoral-fin and anal-fin origins or slightly closer to anal-fin origin. The name Alburnoides thessalicus is now restricted to the populations from the Pinios, Aliakmon and Axios/Vardar rivers. A redescription and designation of neotype for Alburnoides thessalicus is provided. The species can be distinguished from all other congeners in Greek river basins and the Danube and Elbe basins by the presence of a sharp ventral keel in only 2/3 of its length, variably scaled with modally 4–6 scales; usually 12½ branched anal-fin rays; 44–50 + 1–2 pored lateral line scales; 24–31 pre-dorsal scales; snout stout, slightly to clearly rounded; snout length about equivalent to the eye diameter; pelvic-fin origin closer to anal-fin origin than to pectoral-fin. Despite similar morphological characters when compared to other European Alburnoides species, A. economoui differs remarkably genetically from all other studied Alburnoides species. The interspecific genetic divergence based on cytochrome b nucleotide sequences ranges from 7.3 to 8.8% (uncorrected p-distance).

This contribution aims in enhancing knowledge of the zoogeography of the freshwater shrimp fauna of Greece, based on field collections carried out from 2002–2016. A total of 167 specimens were collected from 25 locations in rivers, streams and lakes of the Greek peninsula and islands. Our study adds more localities with exclusive records of A. acheronensis/A. desmarestii in central- western Greece, where it was previously presumed that A. stankoi occurred. Furthermore, A. stankoi is now recorded for the first time in two rivers of eastern central Greece, as well as in a spring system of western Greece, being thus its westernmost record so far.

A wide-ranging river fish survey was executed in the summer of 2009 as part of the preparatory actions for the establishment of a monitoring programme for the EU Water Framework Directive (WFD). This was the first extensive electrofishing campaign for WFD standardized bioassessment in Greece and the experience and insights gained are used here to provide a review of fish-based assessment conditions and requirements in this country. The survey sampled 85 sites on 25 rivers throughout mainland Greece, collecting 70 species of freshwater fish. Quantitative site-based assemblage data is used for taxonomic and ordination analyses revealing a strong biogeographic regionalization in the distribution of the ichthyofauna. The structural and spatial organisation of the fish fauna through the use of species-level and community-level data analyses is explored in three ecoregions where data was deemed sufficient. Transitions in community taxonomic composition among ecoregions were abrupt and concordant with geographical barriers and reflect the influence of historical biogeographic processes. Community-based analysis revealed a substantial degree of variation in quantitative attributes of the fish assemblages among ecoregions. Key conclusions of this work are: (a) the fish-based bioassessment system must be regionalised to reflect biogeographic variation, (b) high faunal heterogeneity among ecoregions (taxonomic, structural), and to a lower degree among basins, constrain the transferability of bioassessment metrics and indices created for explicit regions to other regional frameworks; (c) faunal depauperation in most of the study areas reduce the utility of functional bioassessment metrics and also limits the utilization of rare species and the applicability of the classical form of the “Index of Biotic Integrity” concept. Recommendations to cope with these problems are discussed.