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ABOUT NIPHARGIDS

With over 300 described taxa, the niphargid group of amphipods (Amphipoda: Niphargidae) is the largest genus of European freshwater amphipods. Most of the species are inhabitants of subterranean waters and constitute a substantial part of the European groundwater biodiversity.

The niphargids are distributed across Europe, mainly (but not only) south of the Pleistocene ice sheet boundary extending eastward to the Arabian Peninsula, Turkey and Iran. The genus Niphargus inhabits most of the area, except for most of the Iberian Peninsula, where the seemingly closely related genus Haploginglymus can be found. Most of the taxa exhibit small distributional ranges. Almost 30 % of them are known only from their type localities.

Niphargus presumably differentiated during the upper Tertiary in the basins of the Paratethys and from that region subsequently colonized European freshwaters. Although this opinion is supported by the fact that the highest number of taxa, as well as the highest degree of ecological and morphological differentiation, can be found in the northern parts of Balkan peninsula and in the Danubian-Carpathic region, much older, Eocene fossils shed some doubt on it.

Different species inhabit virtually all types of subterranean waters like interstitial waters, subterranean flows, different types of cave waters, fissure systems (including epikarst), wells and springs, as well as brackish, mineral and thermal waters. In addition, a dozen of species live in surface waters such as forest ditches, Sphagnum moss or small streams.

All Niphargus species, including epigean ones, are eyless. Otherwise, their diverse morphology reflects a diverse ecology. The differences in body size are remarkable: the smallest interstitial species measure two millimeters, while some species reach up to three and a half centimeters. However, most of the variability can be attributed to numerous highly variable body parts combined in a mosaic manner.

 

 

Niphargus hadzii; springs of Ljubljanica, Slovenia. Photo: B. Sket.

Diverse allometric growth patterns contribute substantially to the overall morphological diversity. Allometric growth is differently pronounced and present in various body parts in different taxa. In the shape of certain articles juveniles of a species can resemble some other species, whereas as adults they resemble completely different species.

Recently molecular studies are consistently offering arguments that niphargids are a sister group to crangonyctids. However, the phylogenetic relationships between and within genera remain enigmatic. A small number of markedly aberrant niphargid species was separated into the genera Martynovia, Carinurella, Haploginglymus, Niphargobates, Niphargopsis, Niphargellus, Foroniphargus and Pontoniphargus, with only one to three species per genus. By accepting these genera, Niphargus turns paraphyletic without much profit for taxonomic practice.

A revision of the group is urgently needed. There are numerous topics in the fields of taxonomy, phylogeny, development, functional morphology, biogeography and ecology with unanswered questions.

 

 

 
   
 

A BRIEF HISTORY OF TAXONOMY

The description of “ Gammarus puteanus Koch” published by Panzer in " Faunae Insectorum Germanicae Initia " in 1836 is the first unambiguous record of a Niphargus . A year later Koch (the author of the species!!) published the identical description and drawings in "Deutschlands Crustaceen, Myriapoden und Arachniden”. The genus Niphargus was established 13 years later when Schiödte re-examined his own description of Gammarus stygius from the cave Postojnska jama in Slovenia.

Till 1900 all together 13 taxa were described. The most fruitful period for taxonomy was 1930-1960 when approximately 170 taxa (more than 1 today known taxa) were described. The number of newly described taxa significantly decreased in past years.

Remarkable is contribution of the family Karaman. Father Stanko and his son Gordan described 118 taxa (Stanko 63, Gordan 50, they are co-authors in five descriptions); apart from those Gordan in co-authorship described another 9 taxa. Other important workers are Birštejn (17 taxa), Dobreanu & Manolache (12), Ruffo (10 and 6 in coauthorship), Schellenberg (33) and Sket (20 and 6 in coauthorship).

 

 

 

 

Niphargus shows an extremely diverse morphology with some distinct morphotypes. Not surprisingly, several classifications on these morphotypes were proposed. However, none of these proposals was based on a strict phylogenetic approach. Furthermore, several taxa showing transitional morphology could not be assigned to any of the proposed groups; until now none of these groupings has been widely accepted.

The family Niphargidae was designated by S. Karaman in 1962 and later accepted by Bousfield (1978, 1983). The family consists of genus Niphargus and some smaller genera: Carinurella Sket 1964 (1 species), Foroniphargus Karaman G. 1985 (1 species), Haploginglymus Mateus in Mateus 1958 (3 species), Martynovia Deržavin 1945 (1 species), Niphargobates Sket 1981 (2 species), Niphargopsis Pratz 1866 (1 species), Niphargellus Schellenberg 1933 (2-3(?) species) and Pontoniphargus Dancău 1970 (2 species). The usefulness of these genera is questionable.

In order to get progress in the field of Niphargus taxonomy, five international meetings were organised. The first, known as "I er Colloque International sur le genre Niphargus " was in 1969 in Verona and was followed by the meetings in Lyon (1973), Schiltz (1975), Blacksburg (1978) and Lodz (1980).