On two new or interesting species of the family Niphargidae from Greece and Croatia ( Contribution to the knowledge of the Amphipoda 286 )

New species of the family Niphargidae (Amphipoda Gammaridea), Niphargus impexus, sp. n. is described and figured from the well in Iraklion on Crete Island, Greece, and its taxonomical position within the genus Niphargus is discussed. The species Niphargus salonitanus S. Karaman, 1950 is discovered at the first time on the Lastovo Island (spring Lokanj in Uble village) in the Adriatic Sea, and distribution of this species is mentioned.


Introduction
The numerous discoveries of members of the family Niphargidae (Amphipoda: Gammaridea) in the subterranean waters over central and southern Europe during last 50 years indicated the presence of much higher number of species of this family in these waters as we supposed previously.The recognition of various species remains difficult because of the high morphological similarity of distinct taxa at one side, and high variability of some external morphological characters, at other side.Recently we described a new species Niphargus spasenijae G. Kar., 2015 from brackish waters of Tasos Island (Greece), a taxon similar to Niphargus rhodi S. Kar., 1950b known from Rhodes Island and close to Niphargus longicaudatus-Complex of taxa, where various species differs to each other by very small, distinct morphological characters.
During our recent study of material in hands from the subterranean waters of Croatia and Greece, one new species of the family Niphargidae, Niphargus impexus, sp.n. is discovered and new locality of Niphargus salonitanus S. Kar., 1950a is cited.This is the first citation of genus Niphargus on Crete Island.

Material and Methods
The material of amphipods has been collected by hand-net in the wells and springs.Collected material was preserved in the 70% ethanol.The specimens were dissected using a WILD M20 microscope and drawn using camera lucida attachment.All appendages were temporarily submersed in the mixture of glycerine and

Research Article
water for study and drawing.The body-length of examined specimens was measured from tip of head to end of telson using camera lucida.All illustrations were inked manually.After the end of the study, the dissected body-parts were submerged in Liquid of Faure and covered by cover glass for final preservation.Some morphological terminology and seta formulae follows Karaman`s terminology (G.Karaman, 1969Karaman, , 1993) ) for the last mandibular palpus [A= setae on outer face; B = setae on inner face; C = additional setae on outer face; D = lateral marginal setae; E = distal long setae] and for propodus of gnathopods 1 and 2 (G.Karaman, 2012) [S = corner spine; L = lateral slender serrate spines; M = facial setae; R = subcorner spine on inner face].Terms "setae" and "spines" are used based on shape, not origin.
The advantage of use of Liquid of Faure is the possibility to remove the dissected body-parts from Liquid of Faure by water, and study it again in the various positions under the microscope.The new species is established based on provided morphological and ecological investigations and data.

Diagnosis
Maxilla 1 with 2-3 setae, 6 spines of outer plate with 1 lateral tooth each.Mandible palpus on inner face with several bunches of B-setae.
Pleopods with 2 retinacula, peduncle of pleopods scarcely setose or naked.Urosomal segment 1 in male and female with 1 seta on each dorsolateral side, 1-2 spines on each dorsolateral side of urosomal segment 2.
Uropod 1 in male and female with equally long rami, peduncle with dorsointernal row of setae (only 1 median seta).Uropod 2 with inner ramus slightly longer than outer one.Uropod 3 elongated in males, with long second article of outer ramus.Uropod 3 in females narrowed, with second article of outer ramus exceeding ¼ of first article.Telson short, with marginal and distal spines.
Head with short rostrum and short subrounded lateral cephalic lobes and ventroanterior sinus (fig.4B), eyes absent.
Maxilla 2: inner plate is rather smaller than outer one, both plates with marginal setae only (fig.1E).Maxilliped: inner plate not reaching outer distal margin of palpus article 1 and bearing 3 distal smooth spines mixed with single setae (fig.2E); outer plate not exceeding half of palpus article 2, with row of distomarginal smooth spines; palpus article 2 at inner margin with numerous setae; article 3 at outer margin with one median and one distal bunch of setae (fig.2E); article 4 (dactylus) along inner margin with 2 setae near basis of the nail, along outer margin with one median seta, nail is shorter than pedestal (fig.2E).
Gnathopod 2: article 2 along anterior margin with shorter setae, along posterior margin with row of long setae in proximal part (fig.3D); article 3 at posterior margin with one bunch of setae; article 5 poorly shorter than propodus: (ratio: 45:48).Propodus trapezoid, slightly longer than broad (ratio: 102:95), along posterior margin with 8 transverse rows of setae (fig.3E).Palm slightly convex, inclined nearly half of propodus-length, defined on outer face by one corner S-spine accompanied laterally by 2 L-spines and 4 facial M-setae (fig.3F), on inner face by one short subcorner R-spine (fig.3F).Dactylus reaching or almost exceeding posterior margin of propodus, along outer margin with row of 6 single setae, on inner margin with row of 5-6 short setae (fig.3E).
Pereopods 3 and 4 similar to each other, moderately slender.Pereopod 3: article 2 along posterior proximal margin with row of long setae, along anterior margin with row of short distal setae.Articles 4-6 of different length (ratio: 57:35:43), scarcely setose; article 4 along posterior margin with several single or bunches of setae (fig.4C); article 5 at posterior margin with 2 groups of strong spine-like setae; article 6 along posterior margin with 5 bunches of short spines; dactylus much shorter than pedestal (ratio: 17:43), at inner margin with one spine and seta near basis of the nail (fig.4D), at outer margin with one median plumose seta; nail shorter than pedestal (ratio: 25:30) (fig.4D).
Uropod 1: peduncle longer than rami, with dorsoexternal row of spines, along dorsointernal margin appears only one median seta and distal spine (fig.4G); rami nearly of equal length, outer ramus with 2 median and one distal bunch of moderately long spines, as well as with 2 lateral bunches of simple setae longer than spines (fig.4G).
Uropod 2: peduncle with dorsal median and distal strong spines.Rami nearly of equal length; outer ramus with 2 lateral single strong spines and one bunch of 4 distal strong spines (fig.4G); inner ramus with 2 lateral and 4 distal strong spines, spines remarkably shorter than half of rami-length (fig.4G).
Uropod 3 long, peduncle nearly twice longer than broad, with 2-3 distal short spines.Inner ramus scale-like, much shorter than peduncle, bearing 3 distal spines and one long plumose seta (fig. 2 I).Outer ramus 2-articulated: first article along outer margin with 4 bunches of short spines (fig. 2 I), along inner margin with 5 bunches of spines accompanied by single plumose setae longer than spines themselves; second article slightly shorter than first article (ratio: 103:133), along both margins and tip with bunches of setae as long as or longer than diameter of article itself (fig. 2 I).
Telson slightly broader than long (ratio: 80:73), deeply incised over 2/3 of telson-length (fig.1G); each lobe with 3 long distal spines (the longest spines reaching or almost exceeding half of telson-length) (fig.1G); one distolateral spine is attaches at inner margin of each lobe; a pair of short plumose setae is attached near the middle of each lobe (fig.1G).
Antenna 2: peduncular article 4 slightly longer than article 5 (ratio: 47:39), along ventral margin with one median and one distal bunch of setae (the longest setae are longer than diameter of the article itself); article 5 along ventral margin with 3 bunches of setae longer than diameter of the article itself; flagellum consisting of 8 articles.
Maxilla 1 inner plate with 3 setae (fig.7A), outer plate with 7 spines (one spine with 3 lateral teeth, 6 spines with one lateral tooth), palpus with 7 distal setae.Maxilliped: inner plate with 3 distal spines accompanied by several setae, palpus article 4 at inner margin with 2 setae near basis of the nail.
Pereopods 3-4 rather similar to each other.Pereopod 3: article 2 at anterior margin with row of several proximal long setae and distal short setae, along posterior margin with numerous long setae.Articles 4-6 of unequal length (ratio: 45:33:40), article 4 along both margins with setae (the longest setae are longer than diameter of article itself); article 5 at posterior margin with single spines and setae (fig.7B); article 6 at posterior margin with 5 bunches of short spines and single short setae.Dactylus much shorter than article 6 (ratio: 14:40), along inner margin with one spine and short seta near basis of the nail, along outer margin with one median plumose seta.
As the male of N. rhodi is unknown, and known description of female is not very detailed, further comparison between these two taxa was not possible, although based on zoogeographical history, the taxa in these two very distant islands have rather different origin.

Remarks:
The specimens in hands (3 juv.exp. up to 9.3 mm) have all taxonomical characteristics of N. salonitanus: elongated third peduncular article of antenna 2, flagellum of antenna 2 slender, longer than last peduncular article.Inner plate of maxilla 1 with 3 setae (juvenile exp.).Coxa 1 with subrounded ventroanterior corner.Propodus of gnathopods 1-2 large, with remarkably inclined palm; L-spines on palm of gnathopod 1 propodus sitting laterally of the S-spine; L-spines on palm of gnathopod 2 propodus sitting behind the S-spine; dactylus of gnathopods 1-2 along outer margin with row of single setae.Dactylus of pereopods 3-7 at inner margin with one slender spine or spine-like seta; epimeral plates 1-3 with pointed ventroposterior corner.Article 2 of pereopod 7 broad, with short ventroposterior lobe.Uropod 1 peduncle with dorsointernal row of spines, rami nearly equal, without plumose setae.Uropod 2 inner ramus slightly longer than outer one, both rami without plumose setae.Uropod 3 short.Telson longer than broad, lobes with 3 distal short spines each and a pair of longer lateral plumose setae.
Discovery of this species in another Adriatic island more far from the Dalmatian coast, Lastovo Island, extends known area of distribution of this species on other southern Adriatic islands, and probably this species settled also some other adjacent southern Adriatic islands.