FURTHER DATA ON PECULIAR SUBTERRANEAN FAUNA OF NIPHARGIDAE FAMILY IN GREECE (CONTRIBUTION TO THE KNOWLEDGE OF THE AMPHIPODA 306)

The subterranean species Niphargus karkabounasi Ntakis et al., 2015 (Amphipoda, fam. Niphargidae) was known from type-locality only (AgioiTheodoroi, Korinthos, Peloponnese, Greece). This species is established now in some other localities in Greece, partially redescribed, figured and variability of some of its taxonomical characters are presented. The new peculiar species, Niphargus pararhodi, sp. n. is described from the spring-brook along Gadouras River (Apolona region, Greece) based on one adult male and its taxonomical position regarding other species from Greece is discussed.


INTRODUCTION
The fauna of the subterranean family Niphargidae in Greece has been studied by various scientists and numerous new taxa were discovered and described. Our recent study of this family in Greece show the astonishing variety of taxa: 3 genera and over 20 species and subspecies, despite only partially investigated this fauna in Greece. During present investigation of the material collected in Greece by several scientists from Italy and Holland, new localities and variability of one known endemic species are presented and description of one peculiar new species of the genus Niphargus Schiödte, 1849 is described and figured.

MATERIAL AND METHODS
The collected specimens were preserved in 70℅ ethanol and sent us for determination. The specimens were dissected using a WILD M20 microscope and drawn using camera lucida attachment. All appendages were temporarily submersed in the mixture of glycerin and water for study and drawing. The appendages were transferred to Liquid of Faure on permanent slides. All illustrations were inked manually. Some morphological terminology and setal formulae follow G. Karaman's terminology (Karaman, G., 1969;2012) regarding the last mandibular palpus article [A= setae on outer face; B= setae on inner face; D= lateral marginal setae; E= distal long setae] and propodus of gnathopods 1 and 2 [S= corner S-spine; L= lateral slender serrate L-spines; M= facial M-setae; R= subcorner R-spine on inner face]. Terms "setae" and "spines" are used based on its shape, not origin. Some ecological data of samples-localities of Greece have been published by Pesce & Maggi (1983).
The research in this work is based on the classic morphological, ecological and zoogeographical studies.
Antenna 2 flagellum slender, longer than last peduncular article and consisting of 5 articles.
Labrum broader than long, convex distally (  Gnathopods 1-2 of moderate size, with propodus slightly larger than corresponding coxa. Gnathopod 1: article 3 at posterior margin with one bunch of setae; article 5 much shorter than propodus (ratio: 50:85), with 3 distal setae (fig. 1 I). Propodus trapezoid, longer than broad (ratio: 86:66), along posterior margin with 2 transverse rows of setae ( fig. 1 I). Palm slightly convex, inclined nearly half of propodus-length, defined on outer face by one corer S-spine accompanied laterally by 2 L-spines and 2 facial M-setae, on inner face by one subcorner Rspine. Palm provided with setae of unequal length sitting mainly in distal part of palm. Dactylus reaching posterior margin of propodus and provided with one median seta at outer margin and several setae at inner margin ( fig.1 I).
Gnathopod 2: article 3 at posterior margin with one bunch of setae; article 5 shorter than propodus (ratio: 50:82), with 4 distal setae ( fig. 1J). Propodus trapezoid, almost of the same size of that in gnathopod 1, trapezoid, poorly longer than broad (ratio: 82:72), along posterior margin with 3 transverse rows of setae. Palm convex, inclined nearly to the half of propodus-length, defined on outer face by one S-spine accompanied laterally by one L-spine and one facial M-seta, on inner face by one subcorner R-spine. Palm provided with scarce number of setae. Dactylus reaching posterior margin of propodus and provided with one median seta at outer margin and several setae at inner margin ( fig. 1J).
Pereopods 3-4 relatively slender; dactylus slender, at inner margin with one slender spine neat basis of the nail.
Pereopod 5 shorter than pereopod 6, both moderately slender, article 2 dilated but without ventroposterior lobe, along posterior margin appear several setae only; articles 4-6 along both margins with spines and setae; dactylus slender, at inner margin with slender spine near basis of the nail.
Uropod 2: peduncle with lateral and distal spines; inner ramus with one lateral and 5 distal short spines (fig. 2E); outer ramus remarkably shorter than inner one, with 5 distal short spines.
Uropod 3 long and slender: peduncle rather longer than broad, with 3-4 distal spines; inner ramus very short, scale-like, much shorter than peduncle and provided with 0-1 lateral seta and one distal spine. Outer ramus 2-articulated: first article at outer margin with 3 groups of short spines, at inner margin with 4 bunches of spines, setae absent (fig. 2F); second article slender, reaching up to half of first article and provided with 2-3 lateral and 4 short distal simple setae.
Telson slightly longer than broad (ratio: 80:74), deeply incised, each lobe with 3 distal spines much shorter than half of telson-length, lateral and facial spines absent; a pair of plumose setae attached near the middle of outer margin of lobes ( fig. 3K).
Coxal gills ovoid, relatively short. Oostegites broad, with setae at margins. The males of locality G-93: similar to females, including uropods 1-3. Ntakis et al (2015) mentoned that males differs from females by elongated distal article of uropod 3 outer ramus, but on the figured uropod 3 of male and female it seems to be similar to each other. We observed also large variability of length of distal article of uropod 3 in females and males (reaching 30-50% of first article).
The male of G-94 (3.9 mm) from Korinthos, Agioi Theodoroi: uropod 3 second article of outer ramus elongated, reaching nearly 70 percent of first article ( fig. 3L). Uropod 3 in all other specimens of this locality like that in typical specimens (distal article reaching 1/3 to ½ of first article). Outer ramus of uropod 1 with 0-1 lateral simple seta. Uropod 2 outer ramus of variable length, but always distinctly shorter than inner one. Telson with 3-4 distal spines on each lobe, facial and lateral spines absent ( fig. 3M).

AFFINITY
Niphargus karkabounasi is relatively small species, belonging to the group of Greek species with one seta on gnathopod`s dactylus. Within this group, partially reduced number of D-setae on mandible palpus is present in Niphargus lakusici G. Karaman 2017a, known from Crete Island.
N. lakusici is similar to N. karkabounasi also by shortened outer ramus of uropods 1 and 2, by similar shape of gnathopods and epimeral plates, pleopods, dactylus of pereopods 3-7, but differs from N. karkabounasi by short second article of uropod 3 outer ramus in males, by short inner plate of maxilliped provided with reduced number of distal spines, by short outer ramus of maxilliped, by lobed article 2 of pereopods 5-7, by presence of dorsointernal row of spine-like setae on uropod 1 peduncle, presence of lateral spines on lobes of telson.
As N. lakusici was described based on one male only, more detailed comparison with N. karkabounasi is not reasonable. Both taxa seems to be close to each other despite the geographical distances, and further study on new material of both taxa will show their real taxonomical relation.
Labium broader than long, with well developed subrounded outer lobes and small inner lobes ( fig. 4B).
Maxilliped: inner plate very short, with 2 distal spines accompanied by several setae (fig. 8B); outer plate short, not reaching half of palpus article 2 and provided with 6-7 distolateral teeth and single setae; palpus article 3 at outer margin with one median and one distal bunch of setae; palpus article 4 at inner margin with 2 setae near basis of nail ( fig. 8B).
Pereopods 3-4 moderately slender.Pereopod 3: article 2 along anterior margin with 3 proximal long setae and 4 distal short spine-like setae, along posterior margin are attached 4 long proximal setae and 3-4 setae in distal part. Articles 4-6 of unequal length (ratio: 57:38:40); article 4 at posterior margin with several setae (the longest setae exceeding diameter of article itself), along anterior margin with 4 short spine-like setae ( fig. 6C); article 5 along posterior margin with 4 strong slender spines accompanied by 2 setae; article 6 along posterior margin with 5 groups of single or paired short spines and setae. Dactylus short and strong, much shorter than article 6 (ratio: 19:40), at inner margin with one spine near basis of the nail, along outer margin with one median longer plumose seta ( fig. 6D), nail is much shorter than pedestal (ratio: 17:32).
Pereopod 4: article 2 along anterior margin with 2 long proximal setae and 4 short spine-like setae in distal part of article, along posterior margin are attached 4 long setae in proximal part and 4 strong spine-like setae in distal part of article. Articles 4-6 of unequal length (ratio: 46:38:40); article 2 at posterior margin with 3 groups of setae (the longest setae nearly reaching diameter of article). Article 5 along posterior margin with 3 spines mixed with single short setae; article 6 along posterior margin with 5 bunches of short spines and single setae ( fig. 6E). Dactylus strong, much shorter than article 6 (ratio: 17:40), at inner margin with one spine near basis of the nail ( fig. 6F), along outer margin with one median plumose seta; nail is shorter than pedestal (ratio: 18:30).
Pereopod 5 distinctly shorter than pereopods 6 and 7, with article 2 elongated, much longer than broad (ratio: 82:45), along anterior margin with row of 6 groups of spine-like setae, along posterior almost straight margin with nearly 11 setae, ventroposterior lobe not developed ( fig. 7A). Articles 4-6 of unequal length (ratio: 40:53:56); article 5 along posterior margin with 2 groups of short spines; article 6 along posterior margin with 3 groups of short spines, along anterior margin with 3 groups of setae; article 6 along both margins with 4 bunches of spines mixed with single short setae and with distal bunch of longer spine and setae. Article 2 remarkably longer than article 6 (ratio: 82:56).
Uropod 2: peduncle provided with lateral and distal strong spines; inner ramus is slightly longer than peduncle, provided with 2 lateral spines accompanied by 2 long plumose setae ( fig. 8D), with distal bunch of 5 spines and one plumose seta. Outer ramus slightly shorter than inner ramus, bearing 2 bunches of lateral spines and 2 plumose setae, at tip with bunch of 5 spines ( fig.  8D).
Uropod 3 slender: peduncle much longer than broad (ratio: 56:26); inner ramus very short, scale-like, provided with one distal spine and short seta, and with one long plumose seta ( fig. 4K). Outer ramus 2-articulated: first article along inner (mesial) margin with 6 groups of spines shorter or longer than diameter of the article itself, accompanied by short simple and long plumose seta each; along outer margin of article 1 are attached 6 groups of unequally long spines accompanied sometimes with single simple seta. Second article is much shorter than first one (ratio: 38:150), along both margins with 2-3 bunches of simple setae, at tip appear 2 short simple setae.
Telson slightly longer than broad (ratio: 85:71), slightly gaping, incised almost ¾ of telson length; each lobe with 3 distal spines and one small spine at mesial margin (fig. 6G); a pair of longer plumose setae is attached rather above half of telson-length.
In general, the significant character of the subgenus Orniphargus is the absence or remarkable sexual dimorphic differences (between males and females), short distal article of uropod 3 outer ramus and short spiniferous uropod 3 and spiniferous peduncle of uropod 1. Absence of significant morphological differences between males and females is present also within the members of the subgenus Jovaniphargus S. Karaman 1960 (typus subgeneris: Niphargus jovanovici S. Karaman 1931) and Protoniphargopsis Sket 1957 (typus subgeneris: Niphargus kochianus Bate 1859), although these subgenera are created based on external morphological taxonomic characters.
N. pararhodi differs from N. lindbergi also by different number of ventroposterior spines on urosomite 1, by lower number of retinacula on pleopods 1-3, lower number of setae on inner plate of maxilla 1, etc.
N. lourensis differs from N. pararhodi also by higher number of setae on maxilla 1 inner plate, by different armature of telson, by presence of dorsointernal row of spines on uropod 1-peduncle, etc. But, despite some similarities, N. pararhodi probably don`t belong to Orniphargus group.
The adult females and juv. males of N. rhodi of Rhodos island (G. Karaman, 2017b) differ distinctly from N. pararhodi by absence of plumose setae on uropods 1 and 2, by higher number of distal setae on maxilla 1 palpus, by subequal plates of maxilla 2, by angular epimeral plates, by different shape of gnathopods 1-2 bearing higher number of transverse rows of setae on propodus, gnathopod 2 propodus with 2 L-spines sitting laterally from S-spine.
It remains theoretical possibility that N. pararhodi should be the unknown male of N. rhodi, but we have not enough data to consider N. pararhodi as conspecific with N. rhodi. Further research on new material from Rhodos Island will put more light on the taxonomic status of both species.

ACKNOWLEDGEMENTS.
I am thankful to Prof. Dr. Giuseppe Pesce from Aquilla (Italy) for the part of material used in this study.