Gammarus baysali, Özbek & Yurga & Külköylüoğlu, 2013

Özbek, Murat, Yurga, Levent & Külköylüoğlu, Okan, 2013, Gammarus baysali sp. nov., a new freshwater amphipod species from Turkey (Amphipoda: Gammaridae), Turkish Journal of Zoology 37 (2), pp. 163-171 : 164-171

Gammarus baysali sp. nov. ( Figures 2–7 )

Material. Holotype: Male , 18.1 mm (ESFM-MALI/10-01), collected with a fine-mesh hand-net from Cumayanı Cave, Zonguldak Province, Turkey ( Figure 1 ) (41°29′49″N, 31°53′80″E), 25.ix.2010; collected by Dr O. Külköylüoğlu. Paratypes: Allotype female, 13.2 mm (ESFM-MALI/10-02), same data as holotype. Five males and 3 females (ESFM-MALI/10-03); same data as holotype .

Diagnosis. A large species (max. length 18.1 mm). Very small eyes, long antenna 1 (31 to 44 segmented flagellum), fourth peduncle segment without long setae, fifth peduncle segment and flagellar segments of antenna 2 densely setose, anterior margins of pereopod 5 to 7 with many setae longer than the spines, posterior margins of merus and carpus of pereopod 3 densely setose, flat urosomites, inner ramus/outer ramus ratio of third uropod 0.9.

Description of holotype male. Head ( Figure 2 ): inferior antennal sinus deep. Eyes very small, neither reniform nor kidney-shaped.

Antenna 1 ( Figures 4F, 4 F’): longer than half the body length; setation weak, peduncular segments bear a few distal setae shorter than diameter of segment where they implanted; article 1 stout; primary flagellum with 41 articles; accessory flagellum with 6 articles.

Antenna 2 ( Figure 4C ): ventral margins of peduncular segments armed with 3–9 groups of setae. Setae on fourth peduncular segment are shorter than diameter of segment; setae on fifth peduncular segment are more than twice as long as diameter of segment; setae on dorsal side of both peduncular segments are much shorter; flagellum comprises up to 20 segments; ventral parts of segments with many long setae (more than 2 times longer than segment); flagellar segments not swollen; calceoli absent.

Left mandible (Figure 3H): incisor with 5 teeth; lacina mobilis with 4 dentitions; molar triturative; second article of palp bears 15 setae; third segment armed with 34 D-setae, 5–6 E-setae; 1 group of A-setae, 1 or 2 groups of B-setae; C-setae absent.

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Figure 3. Gammarus baysali sp. nov. Holotype male: A) maxilla 2; B) palp of left maxilla 1; C) right maxilla 1; D) maxilliped; E) upper lip; F) lower lip; G) part of right mandible; H) left mandible; I) telson.

Right mandible (Figure 3G): incisor 4-dentate, lacina mobilis bifurcate.

Maxilla 1 (Figures 3B, 3C): inner plate with 19 plumose setae, outer plate with 10 serrated spines, article 2 of palp with 10 sharp spines, 5 stiff setae; article 2 of right palp stout, with 6 blunt spines on distal part, inner margin with no stiff setae; 2 stiff setae and 4 simple setae on outer margin.

Lower lip (Figure 3F): inner lobe absent.

Upper lip (Figure 3E): convex, with minute setae on distal part.

Maxilla 2 (Figure 3A): inner plate with diagonal row of 21 plumose setae.

Maxilliped (Figure 3D): inner plate with 3 apical spines and 1 subapical spine; outer plate with row of 14–16 spines on medial margin and 5–8 pectinate apical setae.

Coxal plate 1 ( Figure 4D ): slightly dilated on distal margin, with 2 setae on anterodistal margin and 1 seta on posterodistal margin.

Coxal plates 2 and 3 ( Figures 4E , 5D ): subrectangular. Coxal plate 2 with 4 short setae on anterodistal corner, 1 seta on posterodistal corner. Coxal plate 3 with 4 short setae on anterodistal corner, 1 seta on posterodistal corner. Ventral margin of coxal plate 4 almost flat ( Figure 4B ), with 2 setae on anterodistal corner, 6 setae on posterior margin.

Coxal plates 5 and 6 ( Figures 5A, 5B ): bilobate. Anterior lobe of coxal plate 5 small with 1 seta, posterior lobe with 4 setae on posterodistal corner. Coxal plate 6 with 4 setae on posterodistal corner.

Coxal plate 7 ( Figure 5C ): with 18–20 small setae on anterior side, 6 setae on posterior margin. Coxal gills 2–7 present.

Gnathopod 1 ( Figures 4D, 4 D’): basis with long setae (up to 2.5 times longer than diameter of segment) on both anterior and posterior margins; carpus and propodus elongate; propodus with 1 and 2 groups of setae on outer and inner sides of anterior margin, respectively; palm oblique, bearing 1 blunt median spine and 4 (2 + 2) palmar angle spines in addition to some small spines on posterodistal margin of the segment; dactylus with 1 seta on its outer margin.

Gnathopod 2 ( Figures 4E, 4 E’): basis with long setae (up to 2 times longer than diameter of segment) on anterior and posterior margins; anterior margin of carpus with 1 group of setae; propodus subrectangular, with 1 and 4 groups of setae on outer and inner sides of anterior margin, respectively; many groups of setae on posterior margin; median spine present, with 3 spines on posterodistal margin; dactylus with 1 seta on outer margin.

Pereopod 3 ( Figure 5D ): slender; anterior and posterior margins of basis bear many long setae (up to 2 times longer than diameter of segment); merus and carpus densely setose along their posterior margins, setae on posterior margins long (up to 2 times longer than diameter of segment where they implanted); dactylus with 1 serrated seta on outer margin, 2 setae at joint of unguis.

Pereopod 4 ( Figure 5E ): slender; anterior and posterior margins of basis with many long setae; posterior margins of merus and carpus bear many groups of long setae (slightly shorter and sparser than those of pereopod 3); dactylus with 1 serrated seta on outer margin, 2 setae at joint of unguis.

Pereopods 5–7 ( Figures 5A–5C ): elongated; subequal in length; basis of pereopod 5 subrectangular; bases of pereopods 6 and 7 quadrangular and relatively elongated, anterior margins with 6–9 short spines, posterior margins with 20–25 short setae; articles 4–6 slim, with 2–6 groups of spines and/or long setae on anterior and posterior margin of each segment; anterior margin of segments 4 and 5 with many setae longer than spines; sixth segments of pereopods 6 and 7 with many long setae along their posterior margins, dactylus with 1 seta on outer margin, 2 setae at joint of unguis.

Epimeral plates 1–3 ( Figure 5F ): epimeral plate 1 with 1 seta on anterior corner; epimeral plate 2, posterodistal corner slightly pointed, with 5 spines and 3 setae on anteroventral margin; epimeral plate 3, posterodistal corner slightly pointed (never in the form of a sharp hook), with 6 spines and 1 seta on anteroventral margin.

Pleopods 1–3: subequal; peduncle with some setae, bearing 2 retinacula accompanied by a few setae; rami with 19–25 segments, fringed with plumose setae.

Urosomites 1–3 ( Figure 2 ): almost flat; each urosomite bears a dorsomedian and 2 dorsolateral groups of armaments on their posterior margins. Dorsolateral groups of first and second urosomites consist of 2 spines and 4–6 setae. The dorsomedian group of urosomite 1 consists of 1 spine and 3–4 setae, similar to urosomite 2. Third urosomite bears no spine (2–3 short setae only) in its dorsomedian group.

Uropod 1 ( Figure 4B ): peduncle longer than rami, with 1 spine on base and 5 spines on outer margin; inner margin with 2 marginal and 1 distal spines; outer ramus slightly shorter (about 0.9 times as long as inner ramus) than inner ramus, with 4 spines on inner margin; inner ramus with 3 + 3 spines on inner margin.

Uropod 2 ( Figure 4A ): peduncle with 3 and 2 marginal spines on outer and inner margin, respectively, in addition to 2 distal spines; outer ramus shorter than inner ramus (about 0.8 times as long as inner ramus); outer ramus with 3 spines on inner margin; inner ramus with 2 and 3 spines on inner and outer margin, respectively.

Uropod 3 ( Figures 4G, 4 G’): peduncle with 4–6 distal spines; innerramusslightlyshorterthanouterramus (about 0.9 times as long as outer ramus), with many plumose setae and some shorter simple setae on both margins; article 1 of outer ramus with 4 groups of spines on outer margin together with many simple setae; inner margin with many simple setae, first segment of outer ramus bears 3–4 distal spines, article 2 longer than adjacent spines.

Telson (Figure 3I): deeply cleft; each lobe with 2 distal spines together with 4–5 longer distal setae, 3 groups of lateral setae on outer margins and 2 groups of setae on inner margins; the length of distal and lateral setae about 0.6 and 0.4 times as long as the length of telson, respectively.

Description of allotype female. Antenna 1 ( Figure 7D ): peduncle segments with few short setae shorter than diameter of the segment where they implanted; primary flagellum with 37 segments; accessory flagellum with 5 segments. Antenna 2 (Figure 6A): peduncle segments

1 mm

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Figure 6. Gammarus baysali sp. nov. Allotype female: A) antenna 2; B) gnathopod 1; C) gnathopod 2 (inner view); D) pereopod 4; E) pereopod 3.

bear 3–4 groups of short setae on dorsal margin; setae on ventral margin of fifth peduncle segment almost twice as long as the diameter of the segment; flagellum with 17 segments; the setation of flagellar segments is rich and the segments are not swollen; calceoli absent. Gnathopod 1 (Figure 6B): basis with 9 and 13 long setae on both anterior and posterior margins, respectively; setae can be up to 2 times longer than the diameter of basal segment on both margins; propodus ovate with 3 groups of setae on anterior margin, palm not as oblique as that of male, with 2 spines on posterior corner in addition to 2 smaller spines, dactylus with 1 seta on outer margin. Gnathopod 2 (Figure 6C): carpus and propodus elongate, propodus subrectangular, medial palmar spine absent, bearing 2–3 spines on posterior corner and some small spines on inner margin. Pereopods 3–7 (Figures 6D, 6E, 7A–7C): similar setation to those of the male. Uropod 3 ( Figure 7F ): inner ramus shorter than outer ramus (about 0.75 times as long as outer ramus); inner ramus with many plumose setae on both margins and 2 spines on outer margin; article 2 of outer ramus longer than the spines on distal part of first article; inner margin of outer ramus with many plumose setae; outer margin of outer ramus with 3 groups of spines accompanying some simple setae longer than the spines. Oostegites are broad, ovate, and occur on pereopods 2 to 5.

Etymology. This new species is named in honor of İzzet Baysal, the founder of Abant İzzet Baysal University, for his significant philanthropic contributions to life in Bolu, Turkey.

Habitat. Specimens were sampled from the dark zone of Cumayanı Cave. The new species is known from the type locality only. Some of the measured physicochemical features are as follows. Elevation: 147 m; water temperature: 12.7 °C; salinity: 0.5 ppt; pH: 7.51; dissolved oxygen: 2.09; electrical conductivity: 1003 µS.

Remarks. At first glance, this species looks similar to Gammarus obruki Özbek, 2012 , mainly because of the long flagellum of antenna 1 and densely setose antenna 2. However, the absence of well-developed kidney-shaped eyes and the presence of long setae along the anterior margins of the fourth and fifth segments of P5–P7 are the most characteristic features of this new species. In addition, armaments of the palp of the right maxilla, setations of the posterior margin of the fourth and fifth segments of pereopod 4, and the outer margin of outer ramus and telson lobes show differences from those of G. obruki .

This new species also resembles G. syriacus Chevreux, 1895 ; G. rambouseki S. Karaman, 1931; G. ibericus Margalef, 1951 ; G. acalceolatus Pinkster, 1970 ; G. rouxi Pinkster & Goedmakers, 1975 ; G. birsteini Karaman & Pinkster, 1977; G. osellai Karaman & Pinkster, 1977; G.agrarius G. Karaman, 1973; G. crinicaudatus Stock et al., 1998 ; G. zagrosensis Zamanpoore et al., 2009 ; G. shirazinus Zamanpoore et al., 2010 ; and G. loeffleri Zamanpoore et al., 2010 in having a setose anterior margin of P7, but the new species differs from all of them in character combinations (see Table).

The new species also resembles G. monspeliensis Pinkster, 1972 , in having long antenna 1, but G. baysali differs from it by the setation of peduncular segments of antenna 2 and anterior margins of P5–P7, by the shape of epimeral plates, and by the absence of well-developed urosomites (see Table).

Variability. Variability can be found in the number of flagellum segments of antenna 1 in males. Bigger specimens have longer antenna 1, and this character seems

Gammarus syriacus Chevreux, 1895 : Well-developed eyes, telson lobes more elongated, epimeral plates comma-shaped, very sharp.

Gammarus rambouseki S. Karaman, 1931: Small species, small ovoid eyes, urosome segments with setae only.

Gammarus ibericus Margalef, 1951 : Small species, well-developed eyes

Gammarus acalceolatus Pinkster, 1970 : Peduncle segments of antenna 1 with some groups of setae along the dorsal surface.

Gammarus rouxi Pinkster & Goedmakers, 1975 : Small species, antenna 1 short, inner surface of the basis of P7 with setae.

Gammarus baysali sp. nov.: A Gammarus birsteini Karaman & Pinkster, 1977: Well-developed eyes. large species; very small eyes, long

Gammarus osellai Karaman & Pinkster, 1977: Inner lobe of the third uropod shorter, inner surface of the basis of P7 with setae. antenna 1, fifth peduncle segment and flagellar segments of antenna Gammarus agrarius G. Karaman, 1973: Well-developed eyes, very sharply pointed epimeral plates, urosome segments elevated. 2 densely setose, posterior margins of merus and carpus of pereopod Gammarus crinicaudatus Stock et al., 1998 : Well-developed eyes, shorter endopod of uropod 3. 3 densely setose, anterior margins of pereopod 5 to 7 with many Gammarus topkarai Özbek & Balık, 2009 : Well-developed eyes, shorter endopod of uropod 3. setae longer than the spines, flat

Gammarus zagrosensis Zamanpoore et al., 2009 : Well-developed eyes, epimeral plates with many long setae, urosome segments urosomites, inner ramus/outer

moderately elevated. ramus ratio of third uropod 0.9.

Gammarus kesanensis Özbek & Çamur-Elipek, 2010 : Eyeless, inner surface of basal segment of P7 with some setae, second epimeral plate with many long setae.

Gammarus shirazinus Zamanpoore et al., 2010 : Well-developed eyes, antenna 1 with 2 spines on the ventrodistal of first peduncle, peduncle segments of antenna 2 with many long setae.

Gammarus loeffleri Zamanpoore et al., 2010 : Well-developed eyes, small species,shorter endopod of uropod 3.

Gammarus obruki Özbek, 2012 : Well-developed eyes, anterior margins of P5–P7 without long setae.

to be age-dependent. Among the specimens, the number of flagellum segments of antenna 1 varies between 31 and 44 (31, 33, 35, 37, 40, 44). Additionally, bigger males have more setose extremities than the smaller ones. The shape of the eyes never shows variability. Calceoli absent.

Figures

Figure 1. Geographical location of Cumayanı Cave.

Figure 2. Gammarusbaysali sp. nov. Holotype male. Lateral view.

Figure 4. Gammarus baysali sp. nov. Holotype male: A) uropod 2; B) uropod 1; C) antenna 2; D) gnathopod 1 (inner view); D’) detail of gnathopod 1 (outer view); E) gnathopod 2 (inner view); E’) detail of gnathopod 2 (outer view); F) antenna 1; F’) accessory flagellum; G) uropod 3; G’) tip of uropod 3.

Figure 5. Gammarus baysali sp. nov. Holotype male: A) pereopod 5; B) pereopod 6; C) pereopod 7; D) pereopod 3; E) pereopod 4; F) epimeral plates.

Figure 7. Gammarus baysali sp. nov. Allotype female: A) pereopod 5; B) pereopod 7; C) pereopod 6; D) antenna 1; E) telson; F) uropod 3; G) uropod 2; H) uropod 1; I) pereopod 5; J) uropod 3; K) telson; L) pereopod 7; M) pereopod 6.