Niphargus plurispinosus sp . n . ( Crustacea , Amphipoda ) , a stygophile and hypotelminorheic representative from Central Europe

The detailed description of the morphology of Niphargus plurispinosus sp. n. from Slovakia is presented. Over 300 specimens were collected from a permanent seepage spring on repeated visits between May 2011 and May 2013. The type locality is located in the foothills of the Zemplínske vrchy mountains in the East Slovakian Lowland (NE part of Pannonian Lowland) small, low and isolated hills formed during Neogene volcanic activity. Volcanic rocks draw together fragments of massives of Palaezoic and Mesozoic age as same as Neogene sediments. The new species can be classified as stygophile, living in the shallow subterranean habitat. The species has small subequal gnathopods, sexually dimorphic uropod III, sexually non-dimorphic uropod I in juveniles, dimorphic uropod 1 in adults. They are extremely different in the post-reproductive stage, when they have 2-4 dorsal spines (arranged in a transverse row) on the telson and supporting dorsal spines.


Introduction
There are over 300 species and subspecies described in the genus Niphargus Schiödte, 1849, distributed mainly in ground waters of Europe (Boxhall andFišer 2004, Väinöla et al. 2008, http://niphargus.info).Most species have a poor ability to disperse (Trontelj et al. 2009) and many of the taxa are known only from their type locality.The identification of large number of species remains problematic (Fišer et al. 2008b(Fišer et al. , 2009a(Fišer et al. , 2009b)), and species descriptions are of varying quality.The taxonomy of Niphargus has been complicated by regional differences in practice, which are nearly as diverse as the genus itself (Fišer et al. 2009b).
The situation in Slovakia is no different.Eight species of the genus Niphargus are currently known from Slovakia (Košel 2012).Four of them are relatively common, with rather large and well defined distribution areas, and can be relatively easily identified (N.tatrensis Wrześniowski, 1888, N. aggtelekiensis Dudich, 1932, N. hrabei S. Karaman, 1932 andN. valachicus (Dobreanu &Manolache, 1933).Two species, N. bajuvaricus Schellenberg, 1932 andN. inopinatus Schellenberg, 1932, are found in areas of tectonic dislocations with numerous mineral springs (Hudec and Mock 2012).The remaining species are the enigmatic N. carsicus Straškraba, 1956 (sole type sample from the Zádiel Gorge in Slovak Karst) and N. dudichi Hankó, 1924, known from groundwater of SW Slovakia.
Three years of intensive study of superficial subterranean habitats (sensu Meštrov 1962, Culver et al. 2006, Culver and Pipan 2009a, 2009b) of various volcanic regions in eastern Slovakia resulted in the discovery of an undescribed species that was, in early analysis, misidentified as N. baloghi Dudich, 1940 (Hudec and Mock 2012).In contrast to previously described species, characterized with the most one dorsal spine, the species described here possess several dorsal spines on the telson.More detailed analysis revealed this is a new species.
The aim of this paper is to present detailed morphology of this species and to provide some data on its autoecology.

Material and methods
All material was collected at the same locality: South-east Slovakia, south-east foothill of the Zemplínske vrchy Mts.(different to nearby Zemplén Mts. in Hungary), in Hatfa in the village Viničky (48°25'11"N, 21°44'59"E).The mountain chain Zemplínske vrchy Mts. is a small part of the Carpathians (covering an area of about 6 × 15 km, with the highest top at 465,3 m.a.s.l.).The complicated geology includes Paleozoic (non-carbonate), Mesozoic (carbonate) and Tertiary (Sarmatian volcanism, sediments) deposits (Karniš and Kvitkovič 1970).The mountains are close to the eastern slopes of the volcanic Slanské vrchy Mts. which have different Niphargus fauna (unpublished).
The locality Hatfa near the village Viničky is situated on the boundary of areas with different history and bedrock (limestone and volcanic pyroclastics), on the south-east foothills of the hills, close to the limestone area.The type locality is a small, permanent spring close to a private reservoir of groundwater (164 m.a.s.l.), with artificial drainage to the meadow at the east foothill (Fig. 1).Water temperature in the spring is relatively high all year round (10-13°C).Chemical parameters were pH = 7.08, conductivity = 1310 µS, concentration of Ca ions 18.6 mg.L-1 and concentration of Mg ions 32.1 mg.L-1.The stream bed varies from 5-10 cm in width and 1-3 cm in depth.All specimens were collected from a drainage ditch under the stones, leaf litter and grass using a tea-strainer (leg. A. Mock).
Most specimens were preserved in 75% ethanol, with a few samples preserved in 96% ethanol for future DNA-analysis.One to three specimens from numerous samples were morphologically studied.
From all samples we took the smallest and the largest specimens.Adult females were distinguished by the presence of eggs whereas adult males were identified on the basis of having elongated exopodites of uropods III.All other stages were assumed to be correlated with body size (see in Variability chapter).
Specimens were boiled in KOH and chlorophenol; later they were dissected and mounted on slides using SWANN-medium.Fine details were examined using a Leica microscope with magnifications 100-400× using black field or phase contrast.All pendrawing were made using camera lucida.Digital photos were taken with an Olympus DP10 camera mounted on a Leica microscope or stereomicroscope.Etymology.The species name was derived from the Latin words: plus, pluris (= more) spina (=spine, thorn); Niphargus with more then 1 dorsal spine (thorns) on the telson.
Paratypes.More than a dozen specimens deposited in Ljubljana, Slovenia (Collection of C. Fišer), the remaining samples in the authors collection.
All remaining material is retained in the authors´ collection.
Description of adults (paratypes).If it is not specified the characters are the same for both sexes.
Head (Fig. 2: 1; hc).Short angular, without rostrum; anterior margin deep sinusoid (deep incision at the joint of AI and long, lobe); ventral (cheek) margin expressive vaulted.Surface of head capsule is smooth.Minute yellow spot on each side of head between AI and AII present in living specimens, but these quickly fade on preservation.
Labium (Fig. 2: vela; Fig. 3: 4).Larger inner lobes trapezoid-like with sub-triangular flat posterior protruding on each portion; its outer distal () and anterior-inner carries fine feather-like setae.Smaller outer lobes compact and of subovoid shape are fine serrated on distal portion.
Maxillipeds (Fig. 2: mxp; Fig. 3: 5).Inner lobe short with 7 long setae, (6 marginal-plus 1 submarginal seta) and 3 flattened spine-like setae on apical part (); outer lobe reach up to ½ of 2nd segment of maxilliped palp, with 4 isolated longer setae near base and crest of 9-11 flattened spine-like setae which increase distally along inner margin and are followed by 5 longer denticulated setae along distal arc.Outer surface finely setuled.Palp 4-segmented: 1st basal, subtriangular segment with one bunch of 4-5 setae on inner side; 2nd segment, (the longest one) with 14 transversally oriented rows of setae along inner margin and bunch of 7-10 setae close to distal end (outer side) and one bunch of setae near base of inner margin; 3rd segment small sub-oval with two long setae in the middle of dorsal margin and two rows of numerous setae around dactylus; 4th -dactylus with 1 short, bent denticle and 1 short spiniform seta on 2/3 length of ventral margin and one seta in 1/3 of dorsal margin; terminal nail about 1/3 of whole dactylus.
Pereon appendages (Figs 3,5,6).Gnathopods I (Fig. 5: gp-I; Fig. 6: G).Basis -trapezoid broad (L/W ±50%), laterally flattened; a group of longer setae close to anterior ventral angle; two groups of setae.Ischium -sub-quadrangular, bears 7-9 setae on posterior-distal angle.Merus -sub-angular (almost identical with ischium) bears transverse row of setae and a short row of submarginal setae near anterior-distal corner.Carpus -elongate sub-trapezoid with the longest dorsal margin; dorsal margin with 1 group of long setae almost on anterior-distal corner; ventral margin with expressive bulb in ventral base covered with expressive large setae on surface; a submarginal row of setae follows posterior margin; carpus length 60-65% of basis length and 110% of propodit length.Propodus -subquadrate; anterior margin with 3 transverse oriented rows of long setae (two rows along margin and third one almost on anterior-distal corner); distal margin (palm) is convex or almost even with 4 long setae each interrupted with 2-4 minute (thorn-like) setae.Palmar corner with the bunch of 4-5 longer setae close to strong palmar spine; one long, blunt pointed, thick seta; it is followed by 3 shorter, stronger and serrated, spiniform setae on outer side and one supporting minute stout spine on inner surface.Along posterior margin 6-7 transversal rows of numerous setae are present.Two groups of tiny, setae are present on outer surface (close to ventral corner).Dactylus -long (as maximal height of propodit); along anterior margin 6-7 longer, single setae (); along inner margin a row of sparse minute setae.
Gnathopods II (Fig. 3: 10; Fig. 5: gp-II).Basis -trapezoid narrow (L/W ±30%), sub-oval in transsection; sparse row of long, sub-equal setae along anterior margin and three bunches of setae on posterior margin: a) numerous, long setae on basal angle; b) few setae almost in middle position; c) few setae near posterior-distal angle.Ischium -sub-quadrangular, bears 7-9 setae on posterior-distal angle.Merus -sub-angular (almost identical with ischium), bears transverse row of setae and a short row of submarginal setae near anterior-distal corner.Carpus -elongate sub-trapezoid, its dorsal margin the longest; dorsal margin with 2 groups of setae near anterior-distal corner; ventral margin with expressive bulge in ventral base covered with expressive large setae on surface; a submarginal row of setae follows posterior margin; carpus length 70-75% of basis and 120% of propodit.Propodit-subquadrate; anterior margin with 3 transversely oriented rows of long setae (two rows along margin and the third one almost on anterior-distal corner); distal margin (palm) convex with 3-4 longer setae each interrupted with two to four minute (thorn-like) setae.Palmar corner with the bunch of 4-5 longer setae close to base of strong palmar spine; one long, blunt pointed and thick seta and 3 stronger-spiniform serrated setae on palmar corner; one supporting minute stout spine on inner surface.Along posterior margin 6 -7 transversal rows of numerous setae are present.Four groups of doubled or triplet, tiny, spiniform setae are present on outer surface.Dactylus -long (as maximal height of propodit); along anterior margin 6-7 longer, single setae (); along inner margin a row of sparse minute setae.
Propodits of both gnathopods sub-equal in size, the second one slightly larger.Compared to body size, gnathopods are small.
Pereopods III-IV (Fig. 3: 11; Fig. 5: ppIII, ppIV).Both subequal in morphology and size.Secondary spines of each segment have unknown taxonomic value.Distal ends of each propodus with 2 expressive long and 4 shorter seta-like thorns on anterior corner; 2 shorter seta-like thorns and 2 stout thorns on ventral corner correspond with pereopods V. Dactyli III-IV each with long nails (up to 30-40% of dactylus length) with dorsal plumose seta in the proximal third of anterior margin of the article, and one tiny spiniform thorn near the nail base.Spiniform spine is slightly bent to dactylus.
Pereopods V-VII (Fig. 3: 12-13; Fig. 5: ppV -ppVII).Sub-equal in morphology but different in length.Ratio of pereopod V-VII length = 1.0/1.4/1.5, where length of 5th pereopod is almost equal to that one of ppIII and ppIV.Bases V-VII elongateoval (), with convex anterior margins and almost straight posterior margins (), all almost without ventro-distal lobes; length/width ratio = 1.00/0.55-0.65;L-ratio of bases = 1.0/1.2/1.25.Along anterior margins 4-5 slender spiniform setae and one bunch of setae-like thorns on antero-ventral corner; along posterior margins 8-11 small setae.Distal ends of propodit V-VII with characteristic combination of long setae-like thorns and stout thorns on each pereopod: V-equal to pereopods III-IV; 6th VI-with 2 slender setae-like thorns and 2-3 stout thorns on anterior angle and 2 stout thorns on ventral corner; 7th with 2 slender setae-like thorns and 2-3 stout thorns on anterior angle and 2 stout thorns on ventral corner.Morphology and setal patterns of dactyli V-VII are identical to those in dactyli III-IV, however the length of each nail can be variable, probably it is the result of their break or mechanical wear out.
Pleosome section (Figs 2, 5) Pleonites I-III (Fig. 2: epI-epIII).Each composes from two different parts: dorsal and ventral part with epimeral plates on each side.Dorsal part of all pleonites with distinct anterior margin (minute hump on anterior part of distal angle); 6-8 fine setae along dorsal margin (under cover glass it is a part close to the posterior-dorsal corner).Sub-rounded, ventral epimeral plates are clearly distinguished from dorsal part.Epimeral plate I (epI) anterior-ventral corner narrow vaulted forms blunt angle with ventral margin; ventral margin convex, broadly vaulted (without thorns); posteriorventral corner convex and broadly vaulted.Along posterior margin 5-7 setae (the first one is the longest).Epimeral plate II (epII): anterior-ventral corner broadly vaulted; ventral margin slightly convex with 2 submarginal stout thorns; posterior-ventral corner broadly vaulted.Along posterior margin 5-7 seta-like thorns (the fist one is stouter and the longest).Epimeral plate III (epIII): anterior-ventral corner broadly vaulted; ventral margin slightly convex with 3 submarginal thorns; posterior-ventral corner angular or perpendicular () with blunt tip.Along posterior margin 5-7 seta-like thorns (the first one is slightly longer).
Pleopods I-III (Fig. 5: plp).Uniform: each with smooth tubular protopod and two retinacules on distal end; two rami (longer one with 13 articles; shorter one with 15 articles).Each segment bilaterally setuled on distal end, except for the proximal segment.First basal segments 3 to 4-times longer than next segment with row of 4 to 5-times shorter setae on outer margin on shorter arm and smooth on longer segment.The most distal segment is minute and conic.
Uropods I-III: UpI and upII are morphologically similar but the first one is almost twice as long as upII; upIII is sexually dimorphic.
Uropod III -male (Fig. 5: upIII-m; Fig. 7: 4).Up to 35-40% of body length (all following measures are valid for adults).Base sub-oval, short (= 1/4 L of basal segment of exopodite) with numerous, grouped spines along distal margin (around base of exopodite) and 2 stout spines in the middle of ventral margin ().Short endopodite (up to 35-40% of base L ()) bears 2-3 short thorns on distal end and 1-2 minute spines on outer lateral margin.Two-segmented exopodite rod-shaped; basal segment slightly shorter (90-95%) to distal segment; basal segment with 4 groups of spines along ventral margin and 5 groups of spines along dorsal margin; distal segment with 4 groups of longer setae along ventral margin and 3 tiny setae along dorsal margin; distal portion with 4-6 clusters of long setae.
Variability.The main problem when identifying N. plurispinosus (and probably in all species of the Niphargus genus) is to distinguish principal characters sensu International Code of Zoological Nomenclature (International Commission on Zoological Nomenclature 1999) from "characters" which are the result of individual variability based on: a) ontogenesis and expressive heterochrony (Fišer et al. 2008a); b) individual condition, especially by subadults and adults; c) partial predation (or cannibalism?Fig. 7: 4-2) and following regeneration of body appendages; d) influence of environmental variables.
a) Ontogenesis and heterochrony.We identified expressive differences in external morphology among neonates (L up to 4 mm), first developing stage (L up to 6 mm), subadults (about 12 mm by both sexes), adults (L < 15 mm in females, 16 mm in males) and the absolutely largest specimens (L >17 mm in females, 20 mm in males).Without knowledge of the comparative morphology at least of first stages, adults (described above) and the largest (postreproductive?) specimens of N. plurispinosus it is quite easy to identify them as 2-3 separate co-existing subspecies.
Basic difference for the neonate and (or) the first stages of N. plurispinosus are: 1. Head is large relative to BL (Fig. 6: A-B).It bears shorter A1 (25-30 % of BL -because of lower number (8-10) of flagellar segments); A2 reach up to 60 % of A1 and bears 4-5 longer segments in flagellum.2. Gnathopods: both gnathopods with modified subquadrangular propodits with 2-3 transverse rows of few setae along ventral margin (Fig. 6: G); number of transverse rows increase with the individual size of specimens (both as the number of setae in rows).Dactylus with only 2-3 setae along outer margin.() 3. Pereopods V-VII: Bases V-VII oval with expressive ventro-distal lobes, with 2 slender setae along anterior margin and 4-5 relative long setae along posterior margin (Fig. 6: D).Size of all three bases elongated but ventro-posterior lobe decrease with age; setae along anterior and posterior margins increase in number with size.4. Telson bears only 3 apical spines, 2 dorsal spines, and one outer lateral spine more-less in mediate distance between apical-and dorsal spines on one lobe (Fig. 8:  A-B). 5. Pleopods I -III: protopods without retinacules and 4-5 elongate articles in both rami (Fig. 6E).6. Uropod I: exopod and endopod are equal or subeqaul in size; both with small number of spine-like setae (Fig. 6: C; Fig. 7: 6).6. Uropod III: no sexual dimorphism at this size; () all specimens resemble females with reduced number of spines (Fig. 6: F; Fig. 7: 1).The sexual dimorphism is expressed in later (juveniles stages and preadults) as a continuous elongation of distal segment of exopodite (Fig. 7: 2-3) up to same length to basal segment by adults (Fig. 7: 4).
Similar patterns of postembryonic differentiation were noted also in N. aggtelekiensis and N. tatrensis (Hudec and Mock 2011).Neonates and small juveniles are often the only specimens found in sublittoral of different types of streams.This is the reason why it is important to know the morphology of juveniles.
Specimens in probably postreproductive stage were recorded only once (11 May 2013).b) Individual condition.The number of setae on all appendages changes with ontogenesis (Fišer et al. 2008a).However the number of setae (e.g.pleopods, pereopods, upI, upII), or of setal groups (e.g., on up III), evidently correspond to the individual fitness.Therefore they can be variable in specimens of same size (stadium).Also varying number of lateral setae on telson can account to the individual condition.c) Regeneration or degeneration.We found that damaged extremities and body parts form blackish calluses within 12 hours of being damaged.The calluses persist after preservation and their colour is stable after the lightening process in different media (Fig. 7: 4-2, 7).An expressive case of regeneration was observed in a single specimen (subadult male) on the 5th pereopod (Fig. 3: 14): base normally developed, but the rest of the limb was extremely reduced.Specimens with different number of segments on AI-and AII-flagellum and males with different upIII might be probably considered as different stages of regeneration.
On the other hand the largest males (over 20 mm) were commonly found with different asymmetric gnathopods (Fig. 4:1, 1a, 1b, 2), different up III (Fig. 4: 3) damaged AI-and AII-flagellum (reduced number of segments very often without aesthetascs on AI, Fig 8: 4).However we are not sure if these damages are caused by attack, or age, or any kind of degeneration.Predatory behaviour and cannibalism were already observed in some niphargid amphipods (Fišer et al. 2010c, Luštrik et al. 2011).
Remarks on biology.The abundance (=number of animals per visit, when we collected all specimens) of N. plurispinosus in the surface water near the spring ranged from 6 to 68 specimens in 2012 (227 ex. for the whole year).However, less than 8 % of all specimens were adults (12 males, 2 females with eggs and one female with embryos).Ovigerous females were recorded only in spring (March -May).Neonates were reported in June (15 inds.) and July (1 ind.).Juveniles and subadults prevailed in all samples and they were recorded throughout the year (Fig. 9: A).It looks as they leave subsurface actively to search for food in surface water.They were permanently found in the surface water throughout the year without sign of disfunction in mobility or presence of dead specimens.The only exception was in May 2013 of accumulated dead and dying animals.This may have resulted from water fauna poisoning when the owner of the reservoir disinfected the drinkable water by using chemicals with chlorine.Such events seriously endangered the stygophile fauna (Fišer et al. 2010b).
Light-yellow eye spots were seen in a few living adults, but we found no rudimentary eyes.These spots were smaller than those in Synurella ambulans (Müller, 1846).The yellow pigment disappeared within 2 days of preservation in alcohol.
All specimens of N. plurispinosus were found in the shallow ditch low flow volume, up to 15 m away from the source; depending on age.Only juveniles (up to 8 mm of length) were found at the maximum distance (adults up to 5 m; subadults up to 10 m).Water temperature of the spring varied from 10.5°C (January 2012) to 13.8°C (September 2012) (Fig. 9: B).The distribution of specimens along the channel correlates with the water temperate gradient along the channel (Fig. 9: B), suggesting that water temperature over 17°C (July) may be a limiting factor for juveniles.This is in agreement with the known biology of hypotelminorheic habitats (Culver et al. 2006).
N. plurispinosus was the only amphipod species found in the locality.It was collected only from a narrow (width = ± 10 cm) artificial drainage ditch, which originates from the small seep spring in the meadow (Fig. 2) and after 200 m it flows through the underground tube into a small stream with dense population of Gammarus balcanicus Schäferna, 1922.Such a semi-artificial locality can be considered as a unique natural laboratory for the study of biology of subterranean species that penetrate the surface.

Comparison to morphologically similar species
The high number of dorsal spines on the telson lobes is typical for the new described species.But in the determination of the species from the genus Niphargus at least three additional characters need to be checked.In N. plurispinosus these three additional characters are: small gnathopods, sexually dimorphic uropod III (adults and postreproductive stages) and sexually non-dimorphic uropod I in juveniles, but different in adults, and extremely different in postreproductive stage.For comparative purposes, we list three groups of species that share at least two out of the three traits mentioned above.
The first group consists of species with small subequal gnathopods and sexually dimorphic uropod III, but also sexually dimorphic uropod I. Several species sharing this combination have all or some of dactyls of pereopods III-VII armed with at least two spines (e.g.Karaman 1973), but there are also some species without such dactyls N. krameri Schellenberg, 1935(Karaman 1984), N. spinulifemur S. Karaman, 1954(Karaman 1984), N. hadzii Rejic, 1958(Rejic 1958), N. spoeckeri Schellenberg, 1933(Schellenberg 1933, Karaman 1993), N. vinodolensis Fišer, Sket & Stoch, 2006(Fišer et al. 2006) or N. timavi (Karaman 1985), differing in sexually dimorphic uropod I.The presence of a single large individual with sexually dimorphic uropod I indicates some similarity with this group of species.The additional difference between these species and N. plurispinosus is the setal pattern on the dactylus of gnathopods I-II (single seta in N. plurispinosus, several setae in the above listed species).
Finally, a species that share all three aforementioned traits is N. sphagnicolus Rejic, 1958.The difference between N. sphagnicolus and N. plurispinosus includes the setal pattern on gnathopod dactyli I-II (single seta in N. plurispinosus, several setae in groups in N. sphagnicolus); number of spines at the base of uropod I (1-2 in N. sphagnicolus, only one in N. plurispinosus), lower number of submarginal ventral spines at epimeral plate III (3 in N. plurispinosus, 4-5 in N. sphagnicolus) and higher number of setae in maxilla I palpus (up to 9 in N. sphagnicolus and 14 in N. plurispinosus).

Final remarks
A detailed morphological description of Niphargus plurispinosus sp.n. based on large annual samples is presented.This is the first new species from Central Europe for several decades, showing that even this long-investigated territory has higher diversity potential than was supposed; similar situation is also in some other Carpathian regions (Meleg et al. 2013).The precise systematic position of the species is unclear.
There is a very low probability (less than 10%) that all stages will be obtained in one sample.It seems that for the description of a new Niphargus is necessary to obtain: 1.One abundant sample (dozens specimens of different size -including juveniles and adults); such abundant and heterogenous sample is almost impossible to obtain except spring, in such cases as studied in N. plurispinosus.2. One long series of samples (1 year) from one locality, collected monthly.
When describing new species it is very important beside the adult to describe also neonate and if possible also largest specimens in post-reproductive (senior) stages.The principal problem is expressive heterochrony (Fišer et al. 2008a) and how to identify adults.It seems that the key-stone in identification are the females with eggs or embryos.The presence of pleopod retinacules is typical also for subadult that can be found throughout the year.Also the length of distal exopodite segment is enlarged with age.The ratio of both exopodite segments (basal to distal) rise from 0.4 (juveniles) to 1 (adults and seniors).It is necessary to be careful especially at communities with two or more co-existing species of the same genus (cf.Angyal andBalász 2013, Karaman et al. 2010).Maybe for the better understanding of the phenology and life cycle of Niphargus spp. it will be useful to distinguish adult stage of females by the presence of oostegites and adultery of males by the presence of genital papillae.

Figure 1 .
Figure 1.Locality (Viničky-Hatfa) of N. plurispinosus sp.n. in Slovakia: A general view B detail of location where the specimens were collected (Photo: A. Mock).

Figure 6 .
Figure 6.N. plurispinosus sp.n. neonate: A general view B head and anterior part C 1 st and 2 nd uropods D basal segment of 7 th pereopod E 2 nd pleopod F 3 rd uropod G 2 nd gnathopod (Photo: I. Hudec).Not drawn to scale.

Figure 8 .
Figure 8. Variability of telson setae of N. plurispinosus sp.n.: A-E, H juveniles (males and females) F adult male G adult female I postreproductive male J postreproductive female K 3 rd uropod of female (Photo: I. Hudec).Not scaled.

Figure 9 .
Figure 9. Relative abundance (A) and moving activity (B) of N. plurispinosus sp.n. in relation to temperature gradient in the artificial channel of type locality in 2012.Air and water temperatures were measured during collecting of amphipods (around 2.00pm).Notes: F-eggs = females with eggs, F-embryos = females with embryos.Source, 5 m, 10 m = water temperature at various distances from the spring (source).