Distribution of Four Narrowly Endemic Niphargus Species (Crustacea
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ARTICLE IN PRESS Zoologischer Anzeiger 245 (2006) 77–94 www.elsevier.de/jcz Distribution of four narrowly endemic Niphargus species (Crustacea: Amphipoda) in the western Dinaric region with description of a new species Cene Fisˇera,Ã, Boris Sketa, Fabio Stochb aDepartment of Biology, Biotechnical Faculty, University of Ljubljana, Vecˇna pot 111, 1000 Ljubljana, Slovenia bDipartimento di Scienze Ambientali, University of L’Aquila, L’Aquila, Italy Received 2 November 2005; received in revised form 6 April 2006; accepted 10 May 2006 Corresponding Editor: A. Parker Abstract The distribution of four morphologically similar and narrowly endemic Niphargus species living mainly in surface waters of the western Dinaric region was studied. The study area consists of limestone and marls-sandstone (flysch) patches. The variable chemical structure of the flysch affects water conductivity and carbonatic hardness. N. timavi inhabits surface and subterranean waters of low conductivity and carbonatic hardness, both on limestone and flysch. N. spinulifemur is restricted to surface waters with high conductivity and higher carbonatic hardness, exclusively on flysch areas. N. vinodolensis sp. n., described herein, lives both on karst and flysch, where waters exhibit intermediate values of conductivity and carbonatic hardness. N. krameri inhabits surface and subterranean waters with high conductivity and high carbonatic hardness, both on limestone and flysch. This species is in the course of morphological differentiation with three morphological races, probably due to low dispersal ability. The studied species probably do not constitute a monophylum. The easternmost species, N. vinodolensis shows (morphologically, molecularly) close relations with the northeast-Italian N. elegans and with middle-Dalmatian N. illidzensis dalmatinus. It is possible that they differentiated from a common ancestor which inhabited the dry bottom of the northern Adriatic, exposed during the last glacial. We assume that the reasons for the high degree of endemism are historical changes of hydrographical regimes and sea transgressions–regressions. Poor migratory abilities in a geologically diverse landscape restricted further dispersal. r 2006 Elsevier GmbH. All rights reserved. Keywords: Endemism; Dispersal; Distribution; Geological basement; Niphargus 1. Introduction (Fisˇer et al. 2002), distributed from the northern Iberian Peninsula to Iran (Karaman and Ruffo 1986; Karaman The genus Niphargus is the largest genus of European 1998). Most of the species inhabit subterranean waters freshwater amphipods, comprising over 300 taxa and constitute an important part of the European groundwater biodiversity (Sket 1999a). The degree of ÃCorresponding author. Tel.: +386 1 423 33 88; endemism is remarkable and can be well illustrated by fax: +386 1 257 33 90. the fact that almost 30% of taxa are known only from E-mail address: cene.fi[email protected] (C. Fisˇer). their type localities (Karaman and Ruffo 1986). The 0044-5231/$ - see front matter r 2006 Elsevier GmbH. All rights reserved. doi:10.1016/j.jcz.2006.05.003 ARTICLE IN PRESS 78 C. Fisˇer et al. / Zoologischer Anzeiger 245 (2006) 77–94 poor knowledge of their distribution cannot be attrib- the subterranean flow of the Reka/Timavo River uted only to the controversial taxonomy and rarity of between the Trebiciano cave (Labodnica–Grotta di some species, but also to sampling constraints due to Trebiciano) and the springs of Timavo in Duino/Devin limited access to subterranean waters. Not surprisingly, (Karaman 1954; Karaman 1984b) in eastern Italy. The ecological and distributional publications are limited fourth species was reported as ‘‘N. sp.-A [y] similar to (e.g. Ginet 1960a, b; Kureck 1967; Dhomps-Avenas and the Istrian N. spinulifemur’’ and was found in ‘‘springs Mathieu 1983; Gibert 1986) in contrast to the rich and their epigean outflows [y] of the N parts of the taxonomic literature available. The reasons for the high island Krk, as well as the Vinodol region in the opposite rate of endemism of the most diverse freshwater land’’ in the north-western Adriatic coast (Karaman and amphipod genus remain unknown. Sket 1989). It is often overlooked that some niphargid species In the present paper, we address the role played by occur predominantly or even exclusively in surface historical processes and geological patchiness in ex- waters (Sket 1981; Dhomps-Avenas and Mathieu plaining the narrow distribution areas of surface water 1983). Several of them, such as N. valachicus Dobreanu species using Niphargus species, both at the species and & Manolache, 1933 (Sket 1981; Karaman 1998, 2003)or the population level. The impact of some historical N. elegans Garbini, 1894 (see Karaman 1977), are widely processes on the present distribution patterns is postu- distributed. However, narrowly endemic epigean species lated. Finally, taxonomical description of N. vinodolen- are also known. The study of their distribution is much sis sp. n., is given. easier and could provide an insight into the causes that led to this pattern of narrow endemism. The present paper focuses on the distribution of four narrowly endemic Niphargus species that were regarded to be 2. Material and methods closely related from a morphological point of view in former literature (Karaman 1954; Karaman and Sket Samples of N. krameri, N. spinulifemur, N. timavi and 1989). These species live predominantly in surface N. vinodolensis sp. n. collected throughout the study waters of the Istra Peninsula and the surrounding area are deposited in the Department of Biology, regions along the northern Adriatic coast (Fig. 1). Biotechnical Faculty, University of Ljubljana, Slovenia N. krameri (Schellenberg, 1935) and N. spinulifemur and in the Museo Civico di Storia Naturale di Verona, (Karaman, 1954) are inhabitants of the Istra Peninsula Italy. Data from relevant publications (Karaman 1984a; and Italian Venezia Giulia (Karaman 1984a); the latter Stoch 1984; Sket 1988; Karaman and Sket 1989) is restricted to flysch areas (Stoch 1984). N. timavi supplemented data from collections. Species sampling (Karaman, 1954) has long been considered endemic to sites and published information are listed in Appendix. Fig. 1. Distribution of the four Niphargus species considered. ARTICLE IN PRESS C. Fisˇer et al. / Zoologischer Anzeiger 245 (2006) 77–94 79 Samples from collection in Ljubljana were used for the ‘‘Kvarner-Velebit area’’. It includes mainland, five large, morphological analysis. and numerous small islands (Fig. 1). Selected specimens were poured in a 10% hot solution The region is geologically highly heterogeneous, of KOH, briefly rinsed with diluted HCl and washed consisting of alternating limestone and marly sandstone with distilled water. Cleared exoskeletons were stained flysch areas, the latter one in facies of flysch (Mosetti with chlorazol black, partly dissected in glycerol and 1983). Jurassic-Cretaceous carbonatic layers folded mounted on slides in a glycerol-gelatine medium. during Palaeogene formed large synclinal depressions, Morphology was studied under the stereomicroscope viz.: Pazin, Trieste/Trst, Brkini with the Rijecˇina valley Olympus SZX9 (magnification 3.14–114 Â ) and a Zeiss and the Vinodol valley (Fig. 1). In the further text we microscope (magnifications 100–400 Â ). Juvenile speci- use the geological term ‘‘basin’’ for synclinal depres- mens (smaller than approximately 7 mm) that could not sions, where flysch sedimentation occurred. Flysch be identified unambiguously were excluded from the sedimentation started during marine transgressions in analysis. the Palaeocene, reached its climax in mid Eocene, and A distribution analysis at the infraspecific level was ended with the sea regression at the end of the middle possible in N. krameri, where gnathopod setation Eocene. Erosion partially eliminated flysch sediments patterns are characteristic for some races (here not from most anticlines; therefore its remnants can be defined as subspecies). Since the patterns are completely found today mainly in the synclinal basins (Plenicˇar developed only in mature specimens (i.e. females with et al. 1973a; Sˇikic´and Polsˇak 1973; Sˇikic´and Plenicˇar developed oostegites, males with developed genital 1975). The flysch sediments in the basins differ in their papillae) subadult specimens were not included in this chemical composition. In the Trieste and Pazin basins part of the study. flysch clays are mostly carbonatic, while silicate-clay The flysch sediments (details in ‘‘Study area’’) in the prevails in Brkini-Rijecˇina basin (Sˇikic´and Plenicˇar synclinal basins differ in their chemical composition 1975; Mihevc 1994; Babic´and Zupanicˇ1996). (Sˇikic´and Plenicˇar 1975; Mihevc 1994; Babic´and With respect to the geological basement, the study Zupanicˇ 1996). To test whether these differences area was split into seven subregions. Four flysch areas influence chemical properties of water, water tempera- ([1] Brkini with Rijecˇina, [2] Vinodol valley, [3] Trieste ture, pH and conductivity were measured in the field on and [4] Pazin basins) are rather well delimited by the 20th of June 2004. The carbonatic hardness was surrounding limestone territories (Fig. 1). Few small measured a day later in the laboratory. The sampling and isolated limestone patches emerging within these sites are located in the Trieste synclinal basin (stream areas (e.g. Izola near Koper and the area north from between the villages Gabrovica and Osp; stream in Pazin) are too small to be treated as separate regions.