Salaria fluviatilis (Asso, 1801)

Alexander, Timothy & Seehausen, Ole, 2021, Diversity, distribution and community composition of fish in perialpine lakes – “ Projet Lac ” synthesis report, Eawag: Swiss Federal Institute of Aquatic Science and Technology : 147

The freshwater blenny

Salaria fluviatilis

is native to the lakes and streams south of the Alps. Salaria were recorded by Projet Lac in lakes Garda, Maggiore, Lugano and Como. Salaria were also recorded in the northern perialpine lakes Geneva and Annecy.The population in Lake Geneva is phenotypically distinct from the southern perialpine populations in several key traits, including features that are used to distinguish between the species in this genus [191] ( Figure 58 ). For instance, males of the populations of the southern perialpine lakes have blue cephalic pores on the lower part of the cheek, while those from Lake Geneva lack these pores. Barcoding of Salaria from all Projet Lac sampling sites revealed that the Lake Geneva population is genetically distinct from the populations of the southern perialpine lakes.This indicates that Lake Geneva was not colonised from southern Swiss or northern Italian populations of Salaria , but most likely from populations further down the Rhone in France. Following the identification key of Doadrio et al [191], the Lake Geneva population would be diagnosed as typical Salaria fluviatilis , whereas the populations from the lakes south of the Alps would not (given the presence of blue cephalic pores on the lower cheek, which they share with S. atlantica ).

Projet Lac sampling in Lake Maggiore revealed, besides the common phenotype of Salaria , a rare and previously unknown phenotype that is highly distinct in its colour pattern.Three individuals were documented by underwater photography and one of these was collected by hand net.The new phenotype has marbling on the head instead of the diagnostic head stripes of S. fluviatilis and has a broad, dark midlateral band instead of vertical bars on the flank ( Figure 59 ). S. economidisi from LakeTrichonis in Greece has a similar midlateral stripe pattern. Further work with additional collections is required to understand this situation.

Figures

Figure 58: Salaria in Lake Geneva were phenotypically and genetically distinct from those in the southern perialpine lakes. Males of the populations of the southern perialpine lakes, such as Lake Maggiore, have blue cephalic pores on the lower part of the cheek, while those from Lake Geneva (and Annecy) lack the blue iridescence of these pores.

Figure 59. Comparison between common phenotype of subadult Salaria fluviatilis and the new, rare phenotype in Lake Maggiore.The upper four photos were taken with the fish in cuvettes with (left) and without (right) gravel. Lower two photos are of additional individuals of the rare phenotype in their natural habitat. Note the marble pattern on the cheek on the rare phenotype, instead of the diagonal face stripes in the common phenotype. Also the broad, dark midlateral band running along the flank instead of paired vertical bars.