ON TWO PARTIALLY KNOWN SPECIES OF THE GENUS GAMMARUS LEACH 1813/14 (FAM. GAMMARIDAE) FROM ASIA MINOR (TURKEY) (CONTRIBUTION TO THE KNOWLEDGE OF THE AMPHIPODA 304)

Two only partially known species of the family Gammaridae (Crustacea Amphipoda), Gammarus werneri (S. Karaman 1934) and Gammarus paraorientalis G. Kar. (new comb.) are treated. Rivulogammarus kesslerianus werneri ssp. n. has been shortly described by S. Karaman (1934) from Iznik (Asia Minor, NE Turkey) and later considered synonym of Gammarus balcanicus Schäferna 1922 (G. Karaman, 2003).Based on detailed study of holotype and one more recent sample of the same species from Iznik, this species is redescribed, figured and elevated to the species rank, Gammarus werneri (S. Karaman, 1934), belonging to Gammarus balcanicus Complex,Rivulogammarus balcanicus orientalis ssp. n. has been described by S. Karaman (1934) from Derbend [eastern site of Erdschias- dag (=Erciyas-dagi), Asia Minor (Turkey)]. Recently this species was redescribed and figured as distinct species, Gammarus orientalis (S. Karaman, 1934) from type locality and adjacent localities (G. Karaman, 2017). The new study showed that the name Gammarus orientalis is “nomen preoccupatum”, because the species under the same name has been described by Dana (1852) from Sundai, and new name for G. orientalis from Iznik is proposed, Gammarus paraorientalis G. Kar. (new name).


Introduction
The fauna of Amphipoda in Turkey has been investigated remarkably by various scientists during last century (S. Karaman, Schellenberg, Pinkster, G. Karaman, Ruffo, Ozbek etc.) and many new taxa of subterranean and epigean species have been discovered and described, especially of the genera Niphargus and Gammarus. Most of these descriptions are based on classical morphological, ecological and zoogeographical data. Among all these taxa, some of them were described very shortly and with scarce number of figured, making the recognition of these taxa very hard, and sometimes overlooked. Some other described taxa have been neither redescribed more in detail nor collected again, and by this way removed superficially as synonyms of already known species.
Gammarus kesslerianus werneri has been never redescribed nor collected again, and this taxon is here redescribed based on holotype and new sample from the same locality, and elevated to the specific rank, Gammarus werneri (new comb).
Gammarus balcanicus orientalis has been considered synonym of Gammarus balcanicus (Karaman & Pinkster 1987), but later G. Karaman (2017) redescribed this taxon and elevated it to the specific rank, Gammarus orientalis (S. Karaman 1934). Recently it was observed that Dana (1852) has described one new species of Amphipoda under the same name, Gammarus orientalis n. sp. By this way, G. orientalis from Turkey became "nomen preocc.", as we now proposed a new name for it, Gammarus paraorientalis G. Kar. (new name).

Material and Methods
The samples were preserved in 70% ethanol. The specimens were examined from slides and specimens dissected in the mixture of glycerin and water, using a Wild M 20 stereomicroscope. The body length of examined specimens was measured by tracing individual's mid-trunk lengths (tip of the rostrum to end of the telson) and drawings were made using a camera lucida attachment and manually inked. Later, the dissected specimens were transferred on to slides with Faure liquid for final preservation. Some morphological terminology and setae formulae follow G. Karaman's terminology (Karaman, G., 1969) regarding the last mandibular palpus article [A = setae on outer face; B = setae on inner face; C = additional setae on outer face; D = lateral marginal setae; E = distal long setae].Terms "setae" and "spines" are used based on its shape, not origin.

Diagnosis
Metasomal segments smooth, with row of dorsoposterior marginal setae; urosomal segments low, with median and dorsolateral groups of spines and short setae. Urosomal segment 1 at ventroposterior margin with 2 single spines and one bunch of setae. Epimeral plates pointed, with ventral spines. Antenna 1 scarcely setose, antenna 2 with short setae, flagellum moderately slender, calceola usually present in male.
Mouthparts Gammarus balcanicus like. Coxa 1 poorly dilated ventrally, coxa 4 with well developed lobe. Gnathopods 1 and 2 with propodus of the same size but different shape. Pereopods 3-4 with relatively short straight setae. Pereopods 5-7 spinose, with dilated but unlobed article 2, dactylus short and strong. Pleopods with 2 retinacula. Uropods 1-2 with spines. Uropod 3 moderately setose, inner ramus slightly shorter than first article of outer ramus, outer margin of outer ramus with spines and simple setae, inner margin and both margins of inner ramus with plumose setae mixed with short spines; distal article of outer ramus exceeding the spines. Lobes of telson with 2-3 distal spines mixed with single setae, 1-2 setae appear on dorsal face of lobes.     Mouthparts well developed, like these in Gammarus balcanicus. Mandibular palpus 3-articulate, like that in holotype; first article naked; second article with 12 strong setae; article 3 subfalciform, slightly shorter than article 2, provided with nearly 28 D-setae, 3-4 distal E-setae, on outer face is attached one bunch of 5 setae, on inner face appear one bunch of 5 B-setae ( fig. 4E).
Coxae are scarcely setose marginally. Coxa 1 longer than broad (ratio: 58:43), slightly dilated ventrally ( Gnathopods 1 and 2 are subequally long. Gnathopod 1: article 2 along both margins with long setae in proximal part, and shorter setae in distal part ( fig. 2A). Article 3 with one bunch of distoposterior marginal setae; article 5 short, triangular (ratio: 36:23), along anterior margin with one median and one distal bunch of short setae, along posterior margin with 4-5 transverse rows of short setae. Propodus is longer than article 5 and longer than broad (ratio: 51:36), pyriform, along posterior margin with 4 transverse rows of straight setae mixed with single short spines; palm long, slightly concave, with median strong spine accompanied by bunch of long straight setae; anterior margin with scarce number of short setae ( fig. 2B). Dactylus along outer margin with one median seta, along inner margin naked. Propodus of holotype like that of male 8 mm ( fig. 4G).
Gnathopod 2: article 2 along both margins with long setae in proximal part and shorter setae in distal part; article 3 with one bunch of posterior marginal setae ( fig. 2C). Article 5 triangular and longer than broad (ratio: 36:24), along anterior margin with one median and one distal bunch of setae, along posterior margin with nearly 6 transverse rows of short setae. Propodus is longer than article 5 (ratio: 47:36), longer than broad (ratio: 100:55), along posterior margin with nearly 7 transverse rows of straight setae, along anterior margin with 3-4 bunches of straight setae. Palm concave, with one strong median spine accompanied by bunch of long strait setae ( fig. 2D). Dactylus with one median seta at outer margin, inner margin naked. Propodus of holotype like that of male 8.0 mm ( fig. 4H).
Pereopods 3 and 4 moderately slender, with pilosity like Gammarus balcanicus. Pereopod 3: article 2 with long setae at both margins. Articles 4-6 of unequal length (ratio: 52:31:37). Article 4 at posterior margin with nearly 5 bunches of straight setae as long as or slightly longer than diameter of article itself, along anterior margin with 3 bunches of short setae accompanied by single spine. Article 5 at posterior margin with 4 groups of short spines accompanied by single very short setae; article 6 along posterior margin with 5 groups of short spines and single short setae; dactylus short, with spine at inner margin ( fig. 1E).
Pereopod 4 is rather shorter than pereopod 3, article 2 along both margins with long setae; articles 4-6 of unequal length (ratio: 40:33:35); article 4 at posterior margin with several groups of short setae up to as long as diameter of article itself ( fig. 1F), along anterior margin with 2 groups of short spines accompanied by single short setae; article 5 at posterior margin 3 groups of short spines, along anterior margin with distal bunch of spines. Article 6 along posterior margin with 4 groups of short spines mixed with single short setae; dactylus short and strong, at inner margin with spine-like seta near basis of nail.
Pereopod 7: article 2 is longer than broad (ratio: 78:51), along anterior poorly convex margin appear nearly 6 spines and one proximal group of setae; along posterior convex margin appear a row of nearly 11 short setae; on inner face of article 2 appear one submarginal ventral spine and one proximal group of 5 short setae ( fig. 3E); ventroposterior corner short. Articles 4-6 of unequal length (ratio: 47:57:60), along both margins with bunches of short spines, sometimes with single short seta. Article 6 is shorter than article 2 (ratio:60:78); dactylus much shorter than article 6 (ratio: 21:60), at inner margin with one spine-like seta near basis of the nail, along outer margin with one median plumose seta ( fig. 3F); nail shorter than pedestal (ratio: 22:50). Article 2 of holotype like that of male 8.0 mm, along posterior margin with 13 short setae, on inner face with one proximal facial bunch of 4 short setae and one distal facial spine and 1 short seta ( fig. 5A).
Uropod 2: inner ramus is distinctly longer than outer one, both rami with lateral and 4 distal spines. Uropod 3 moderately slender: peduncle longer than broad (50:29), with one lateral group of 2 spines and several distal spines; inner ramus is slightly shorter than first article of outer ramus, provided at outer and inner (mesial) margin with single long plumose setae, accompanied along outer margin with 4 single spines, at tip appear 2 spines and several setae ( fig. 2F). Outer ramus 2-articulated, first article along inner margin with row of long plumose setae, along outer margin appear a row of 5 bunches of short spines mixed with longer simple setae; second article much short, but longer than distal spines of first article and bearing 3 distal simple setae. Pilosity of holotype on slide like that of male 8.0 mm; inner ramus of one uropod 3 is slightly shorter, like that of male 8.0 mm ( fig. 5C), other uropod 3 is slightly more elongated (figured also by S. Karaman (1934), here figured with omitted setae and spines ( fig. 5B).
Telson poorly longer than broad, lobes with 2 distal short spines mixed with 3 unequal simple setae shorter or longer than spines ( fig. 1G) and by one group of 2 submarginal setae in distal part of lobe; a pair of very short plumose setae appear in distal half of each lobe. Telson in holotype like that in male 8.0 mm, right lobe distally with 2 spines accompanied by 2 setae attached very close to each other (right lobe with 3 spines figured on S. Karaman figure, some setae probably broken).
Antenna 2 moderately slender; peduncular articles 4 and 5 of nearly same length; article 4 at ventral margin with 3 bunches of setae (the longest setae exceeding diameter of article itself) ( fig. 7A), at dorsal side setae are rather shorter; article 5 along ventral margin with several bunches of setae longer than diameter of article itself, setae at dorsal side are rather shorter; flagellum moderately slender, consisting of 8 articles with setae slightly longer than these in male. Antennal gland cone slightly longer than that in males ( fig. 7A).
Gnathopod 2 scarcely longer than gnathopod 1: article 2 along anterior and posterior margin with long setae, several short setae appear at the ventral tip of article only; article 3 at posterior margin with one bunch of setae; article 5 narrowed, longer than broad (ratio: 35:20) at anterior margin with 2 bunches of setae, at posterior margin with nearly 5 transverse rows of setae ( fig. 6C). Propodus longer than broad (ratio: 67:34), linear, along anterior margin with 3 bunches of long setae, at posterior margin with nearly 4 transverse rows of setae; palm inclined, without median palmar spine, at distal corner with one spine (fig. 6D); dactylus reaching posterior margin of propodus, with one median seta at outer margin, inner margin almost naked.
Pereopods 3 and 4 slightly shorter than these in male. Pereopod 3: article 2 along both margins with long setae, in distal part of article setae are rather shorter. Articles 4-6 of different length (ratio: 42:28:31); article 4 at posterior margin with 4-5 bunches of long simple setae (the longest setae exceeding diameter of article itself), along anterior margin appear 3 groups of short spines and short single setae (fig. 7B); article 5 at posterior margin with 4 short spines, along anterior margin with distal bunch of short setae and spines; article 6 at posterior margin with 4 groups of short spines, at anterior margin with distal group of setae. Dactylus short, like that in male, at inner margin with one spine-like seta, at outer margin with one median seta.
Pereopod 4 is slightly shorter than pereopod 3; article 2 at both margins with long proximal and shorter distal setae ( fig. 7C). Articles 4-6 of different length (ratio: 36:28:30); article 4 at posterior margin with 5 bunches of long setae (the longest setae slightly exceeding diameter of article itself), at anterior margin with 2 groups of setae ( fig. 7C); article 5 at posterior margin with 3 single or paired short spines, at anterior margin with distal group of spines and setae. Article 6 along posterior margin with 3 groups of short spines, at anterior margin with distal group of setae. Dactylus like that in pereopod 3.
Pereopods 5-7 like these in males but slightly shorter, with article 2 slightly broader than these in males. Pereopod 5 article 2 slightly longer than broad (ratio: 65:60), anterior convex margin provided with row of nearly 8 short spines and one proximal longer seta, at posterior margin with 7-8 short setae, ventroposterior dilatation well developed, but not lobed ( fig. 6F).
Uropod 2: inner ramus is distinctly longer than outer one, both rami with single lateral and 4 distal unequal spines.
Uropod 3 missing. Telson is poorly longer than broad (ratio: 70:68), each lobe is provided with 2-3 distal spines accompanied by single setae in distal part of each lobe and by one facial seta and one pair of short plumose setae ( fig. 5F).
Coxal gills like these in male. Oostegites lacking marginal setae. Description of S. Karaman is very short, with 2 figures (uropod 3 and telson). He mentioned that Rivulogammarus kesslerianus werneri is mainly similar to Rivulogammarus kesslerianus Martynov 1931 by longer inner ramus of uropod 3, and that body is with very scarce pilosity, especially pereopods, antenna 2 and uropod 3. He mentioned that by all specimens telson is with 2-3 distal spines, and that apical article of uropod 3 outer ramus is longer than spines near it. He mentioned that werneri differs from Rivulogammarus pulex danubialis S. Kar. 1931b (= G. fossarum complex) by constant presence of 2 spines on tip of telson lobes as well as by longer apical article of uropod 3 outer ramus.