Gammarus zagrosensis, Zamanpoore, Mehrdad, Poeckl, Manfred, Grabowski, Michal & Schiemer, Friedrich, 2009

Zamanpoore, Mehrdad, Poeckl, Manfred, Grabowski, Michal & Schiemer, Friedrich, 2009, Two new sympatric species of freshwater Gammarus (Crustacea: Amphipoda) from Southern Zagros Region, Iran, Zootaxa 2136, pp. 21-39 : 23-31

Gammarus zagrosensis n. sp.

( Figs. 2–5 )

Material examined. Many males and females. Male holotype, body length 17.4 mm, February & August 2007, coll. M. Zamanpoore. Locus typicus: Vezge-Morad spring (locality 2), 2 km S of Sepidan, Fars Province, Iran (30°13´N, 51°58´E), Altitude 2190 m. Paratypes, many males and females; same date and locality. Additional samples: Khani Varg spring (locality 3), 4 km S of Sepidan (30°12´N, 51°59´E), Altitude 2053 m; Baraghan spring (locality 4), 5 km SE of Sepidan (30°15´N, 51°59´E), Altitude 2212 m; Shesh-Peer (spring brook) (locality 5), 10 km SE of Sepidan (30°15´N, 52°03´E), Altitude 2350 m. All specimens including type series are kept in the amphipod collection of the Museum of Fars Research Centre of Agriculture and Natural Resources (FARSAGRES), Shiraz, Iran. Holotype is deposited in the Zoological Museum of Amsterdam ( ZMA, Amph. 206052, 2009). Descriptions were based on the holotype, and compared to 5 winter and 5 summer paratypes from the type locality for variations. Paratypes were completely dissected for staining with Lignin Pink and mounted with Euparal (Carl Roth GmbH & Co) on microscope slides.

Diagnosis. Medium-sized to large species. In general, this species can be distinguished from other adjacent species by a combination of the following characters: (1) extra-ordinary long setae on inferior margin of EP2 and 3, (2) endopodite of U3 about 3/4th of exopodite, (3) existence of some setae on postero-distal corner of P6 and P7, and (4) antenna 2 with short setae on flagellum and bearing calceoli.

Etymology. The specific name zagrosensis is an adjective made from the name of the Zagros Mountain Chains, located along the eastern edge of the Iranian Plateau, an area with a high biodiversity. The type locality is in its southern part.

Description. Male. Maximum body length (based on 100 individuals) 22 mm. Body robust; lateral cephalic lobes more or less rounded, anterior lower part of head extended forward; eyes elliptical to slightly reniform, short (less than diameter of first segment of antenna 1), less than twice as long as wide ( Fig. 2 A).

Antenna 1: About one-third of total body length, third peduncle segment shorter than first and second, about half length of first. Main and accessory flagellums with 28–32 and 3–4 segments, respectively, with very short simple setae in groups of 5 on each side ( Fig. 2 B).

Antenna 2: Gland cones rather slender, not reaching distal end of third peduncle segment; peduncle segments 4 and 5 of almost equal length, armed with tufts of setae of the same length or slightly longer than diameter of segments; flagellum with 11–17 segments which are not swollen or compressed; groups of setae near to the end of each flagellar segment at both outer and inner surfaces. A row of setae implanted submarginal to the distal end of each segment at the inner surface, never forming a flag-like brush; calceoli present ( Fig. 2 C).

Mandible: Incisor processes, lacinia mobilis and ridged molar process well developed, a plumose long spine row present ( Fig. 2 D).

Mandible palp: First segment not armed; second segment with ventral setae, 4–5 proximal setae shorter than the width of the segment and 7–10 closely placed distal setae longer than the width of the segment; inferior margin of the third segment armed with a comb-like row of 25–29 D-setae, 3–4 long E-setae, two groups of B-setae and one group of A-setae ( Fig. 2 E).

Labium: Simple, with a group of short setae on the apices of the inner lobe, and a group of very fine bristles on inner and outer lobe.

Maxilla 1: Inner basal lobe with long finely plumose setae; outer lobe with stout serrate spines; left palp at its end has an armature of 4 median spines accompanied by a short seta, one longer separate subapical spine on its outer margin and 3 smaller spines on distal inner angle ( Fig. 2 G), right palp with five robust tooth-like spines at its end, one longer separate subapical spine on its outer margin opposed by one smaller spine, anterodistally ( Fig. 2 H).

Maxillipedes: Exopodite with a row of three distal strong teeth, accompanied by three short thick setae; a row of setae on distal margin becomes plumose from the middle towards the inferior side, where it joins about 10 very long regularly placed plumose setae at the inferior edge ( Fig. 2 F); endopodite with a row of long distal plumose setae which gradually shorten and lose plumosity towards the interior, joining to a row of inferior strong spine-teeth gradually shorten proximally and finally merging to a row of long setae. The palp is well developed.

Gnathopod 1: Coxal plate distally not or slightly wider than proximally, rounded corners with a setae at the postero-ventral corner and three to four setae at antero-ventral corner, one fine setae at 1/4th of the postero-ventral surface of the plate; basis is expanded at 1/3rd, gradually becomes narrower toward the base of the segment; carpus and merus with groups of setae which are plumose at posterior margin of carpus; propodus pyriform, palm oblique with one medial palmar spine and several palmar angle spines, five groups of small spines at posterior palmar margin, a group of four setae very close to medial palmar spine, two groups of setae at the propodal anterior margin, a row of five groups of short setae on propodal surface, a row of three groups of small spines (2 each) on posterior sab-margin, dactylus long ( Fig. 3 A).

Gnathopod 2: Distal end of coxal plate finely narrower than proximal; propodus is less elongated than propodus of GP1; posterior propodal margin is convex; a group of setae close to the medial palmar spine, two groups of setae at propodal anterior margin; palm is oblique having a robust medial palmar spine and palmar angle spines (3) ( Fig. 3 B).

Pereopod 3: Coxal plate rounded distally, concave posteriorly, convex at anterior margin, with 3–4 very short setae implanted at antero-distal corner, one at postero-distal corner, and a longer setae on outer surface of the plate. Basis-carpus bear groups of setae at posterior margin, about 1 to 1.5 times as long as the diameter of the segments in basis and ischium; those of merus and carpus are in dense groups and 2–3 times longer than the diameter of the segments; anterior margin of merus with two groups of few short setae and a shorter spine, and another group of long setae and a spine at anterior tip; carpus has one spine among each of its first three groups of setae, and a long spine and a group of longer setae are implanted on both its anterior and posterior tip; posterior margin of propodus with 5 groups of one small spine and some long setae ( Fig. 3 C).

Pereopod 4: Coxal plate with five small setae implanted at antero-distal margin and eight at postero-distal margin; segments similar to pereopod 3, but setae are shorter and the number of setae and groups is lower. Anterior margin of merus with just one group of short setae and one spine, one long spine implanted at anterior tip among a group of setae; carpus has two spines among most groups of setae ( Fig. 3 D).

Pereopod 5: Basis with a sub-rectangular shape, posterior margin slightly concave (variation: straight to slightly convex in some individuals), postero-distal lobe well developed, posterior margin with 14 very short setae, anterior basis with one to two groups of 3 marginal setae, 3-4 spines mixed with a fine seta, one seta at sub-margin of antero-proximal part of basis; merus and carpus with small spines and setae (as long as spines), propodus having 6 transverse rows of spines (2–3–3–3–3–2) ( Fig. 4 A).

Pereopod 6: Similar to pereopod 5, but longer (1.2 times longer than P5); basis more slender and more concave at postero-distal, 1–3 setae at the inner surface of the postero-distal corner of protruding lobe ( Fig. 4 B).

Pereopod 7: Basis wider proximally; postero-distal protruding lobe less developed than P6, set with few long setae at postero-inferior corner, 18 very short setae on posterior margin, starting from the base of the basis; anterior margin of merus and carpus with spines and longer setae; merus with a long spine and some short setae at the middle of posterior margin; carpus with one long and one smaller spine at two-third of posterior margin; propodus with spines and setae which are as long as spines, 7 transverse rows of spines on anterior margin of propodus (3–3–3–3–3–3–2); 2 longer spines at posterior tip of propodus intermixed with a group of longer setae ( Fig. 4 C).

Uropod 3: Endopodite more than two-thirds (0.71) of the exopodite; setae on both rami are more than twice as long as the width of the part of the segment they are implanted on, many setae on outer margin of both exopodite and endopodite are plumose, a group of 1 spine and 5 setae on two-thirds of the basis and a number of setae and short to long robust spines implanted on the apex; long spines at intervals on outer margins of endopodite and exopodite ( Fig. 3 E).

Epimeres: Posterior-inferior corner of the first epimeral plate rounded with a small pointed node, 6–8 long setae on antero-distal corner; EP2 sub-rectangular with rounded anterior margin, EP3 moderately pointed; 4–7 extraordinary long setae on distal sub-marginal area of 2nd and 3rd plate rarely mixed with spine; a row of setules on posterior margin of all 3 plates; dorsal surface of metasomites posteriorly covered with very short setules ( Fig. 4 E).

Telson: Rather elongated, length of the lobes about twice their widest width; two to three long and robust spines and some 5–7 long setae on distal margin; four groups of 2–6 setae at the dorsal surface of the lobes ( Fig. 2 I).

Urosomites: Moderate elevations on postero-dorsal of urosome segments, dorsal armature consists of 1–2 lateral spines and 2 mid-dorsal spines, all combined with some short setae ( Fig. 4 D).

Female.

Female is:

- Smaller than male (12 mm.).

- Palm in propodus of gnathopod 1 is less oblique; medial palmar spine absent, one long palmar angle

spine, with 2–3 spines at posterior palmar margin, a group of setae at the medial palmar region. - Propodus of gnathopod 2 sub-rectangular in shape, and lack the medial palmar spine; 2 palmar angle

spines, a group of setae at medial palmar region, no spines on posterior palmar margin. - Propodus of gnathopod 1 and 2 is smaller in respect to the other segments, and the whole appendage

smaller than in males.

- Proximal 3/4th of gnathopod 1 and 2 bases are not wider than their distal part.

- Basis of pereopods 5–7 less elongated than in males, rather distinct convex angles at the middle of

posterior edges ( Fig. 5 A–C).

- Epimeral plates of the females do not show any significant variation in respect to those of the males ( Fig.

5D). Oostegite 1 is illustrated in figure 5E.

Cuticular ultrastructure: HC cuticular polygons with both linear and scattered types of pore arrangements ( Fig. 6 , left); lines with a distance of 0.56–1.48 (Mean = 0.97, SD = 0.20); density of pores in line-type (L-type) polygons 62–80 pores per 25 µm2 (Mean = 71, SD = 5), while scattered-type (S-type) polygons with higher density of 75–244 pores per 25 m 2 (Mean = 163, SD = 52).

Discussion. Gammarus zagrosensis shows minute similarities with some of the well known taxa. Comparisons with these morphologically closest species, and species from adjacent regions are given here.

This species has some similarities with G. lacustris G. O. Sars, 1863 , a widely distributed species, e.g. the relatively short A1, shape and armature of U3, and of telson. On the other hand, the new species differs from G. lacustris by its elliptical eye, much denser and longer setae on P3–4; existence of setae on merus and carpus of P7 (as long as/longer than twice the length of spines) and the posterior-inferior corner setae of P7 basis, having dorsal elevation on epimeres, non-sharp EP2, long setae on EP2 and EP3, in addition to long setae on the tip of telson, which can clearly differentiate these two species.

G. ro u x i Pinkster & Goedmakers, 1975 is the only species having long setae on EP 2 and 3, in addition to possession of setules on metasomites' dorsal surfaces, but has many other features which separate it strongly from this species, among them are: much shorter A1 and A2, short and very few setae on U3 and telson, less pointed EP3, longer setae on A2, longer setae on P5–7 segments, very different shape of P6 and P7 basis and having many setae on their interior surface. It is also worthy to add the point that G. ro u x i has been reported from North Africa, far distant from Iran.

G. pseudosyriacus Karaman & Pinkster, 1977, which has been reported by Stock et al. (1998) in the adjacent western province, has larger eyes, less setose A1, shorter setae on A2, a longer antennal gland cone (reaches to the tip of the third peduncle segment), less spines on posterior propodus margin of GP1, no setae on P5–7 merus and carpus, and the posterior-inferior corner setae, shorter setae on both endo- and exopodite of U3, and more pointed EP2 without long setae on inferior margin of EP1 and EP2.

G. crinicaudatus Stock et al., 1998 , which was firstly reported and described from inside Fars Province, has a shorter antennal gland cone, longer and more groups of setae on A2, merus and carpus of P5–7, and also on dorsal of epimeres, fewer groups of setae on GP1 propodus surface, additional accessory spines near the palmar angle spine, more numerous long setae on telson, and no long setae on EP2 and EP3.

G. bakhteyaricus Khalaji-Pirbalouty & Sari, 2004 reported and described from the neighbouring province at North-West of the location has shorter setae on A2, and shorter setae and spines on telson. It has two rows of setae and a row of small spines on the palm face of GP1 and two rows of setae, in addition of small accessory spines, near the palmar angle spine in GP2, and a much sharper EP2. P5–7 without setae on merus and carpus, P7 basis has a higher length/width ratio.

G. lordeganensis Khalaji-Pirbalouty & Sari, 2004 reported and described from the same province as G. bakhteyaricus has a higher number and length of setae on A2, shorter setae on both endo- and exopodite of U3 and no plumose setae on exopodite external margin, and shorter setae and spines on telson. Coxal plate of GP1 is much wider at distal than proximal; it has two rows of setae and a row of small spines on the palm face of GP1 and two rows of setae in addition of small accessory spines close to the palmar angle spine in GP2, sharper EP2 and EP3 and a specifically characteristic lobate shape of EP 3 in male and female; P5–7 bear no setae on merus and carpus, and P7 basis has a lower length/width ratio.

G. balutchi ( Khalaji-Pirbalouty & Sari, 2006 reported and described from Lorestan province (North to Sepidan County) show long setae on peduncles of A2, much shorter endopodite of U3, and not elevated epimere dorsal; it has two rows of setae and a row of small spines on the palm face of GP1 and two rows of setae in addition of small accessory spines near the palmar angle spine in GP2, P7 basis has a higher length/ width ratio, and no posterior-inferior corner setae.

G. lobifer Stock et al., 1998 , firstly reported and described from the western adjacent province, has a shorter endopodite of U3, and dorsal of epimere is not elevated; the armature of GP1 and GP2 are similar to G. balutchi ; basis of P7 with lower length/width ratio, and only one short posterior-inferior corner setae in contrast to 1–4 longer in G. zagrosensis .

G. subequalis ( Martynov, 1935) (Figs. 30-39) described from Karatau Mountains (Southern Kazakhstan) shares with G. zagrosensis similar setation of peduncle and flagellum of A2, armature of merus to propodus of P7 and richly setose U3 with similar ratio of endo-/exopodite. However, in contrast to G. zagrosensis it possesses less setose and longer (ca. 1/2 of total body length) A1, P7 basis with spine accompanied by few equally long setae at postero-interior corner, different shape of epimeral plates armed with spines and short setae only, and much shorter setae around apical spines on telson. Also, Martynov (1935) does not mention presence of setules on dorsal surface of metasomites in this species.

G. suifunensis Martynov, 1925 , reported from Ural Mountains, Russia ( Karaman 1991; Figs. I–VI), has a similar weak setation of P6–7, very short U3 endopodite, but endopodite is much shorter (one-third of exopodite), gland cone is shorter than the segment, A2, P3–4, and U3 (exo- and endopodite) are poorly setose, and eyes are smaller compared to G. zagrosensis .

G. koreanus Ueno, 1940 , originally described from NE Korea which is also reported from Khabarovsk, Far East Russia ( Karaman, 1991, Figs. VII–X), shares the poor setation of P5–7, highly setose U3 (exo- and endopodite) and long endopodite, and setose P3–4 with G. zagrosensis . On the other hand, G. koreanus shows poorly setose A1 and A2 peduncles and flagellum, shorter gland cone, longer U3 endopodite, and seate on posterodorsal corner of P7 basis.

G. paucispinus Hou & Li, 2002 , distributed in Yunnan Province, South China, show similarities with G. zagrosensis in its non-setose P5–7, having long setae on telson, non-pointed EP with small spines, and U3 endopodite 1/2 the exopodite. However, it has a poorly setose A1, less setose A2, shorter antennal gland cone, less setose P3–4, and poorely spinous urosomites ( Hou & Li, 2002; Figs. 1–4 ).

Additionally, some shared features can be distinguished between G. zagrosensis and G. m a d i d u s Hou & Li, 2005 (from around Beijing, China), including long setae on P4, bared P5–7, and short U3 endopodite, but G. madidus can be easily recognized from the new species by its small eye, poorly setose A1, moderately setose A2, shorter gland cone, short setae on P3, postero-distal corner setae on P7 basis, non-pointed EP, U3 endopodite still shorter than 1/2 the length of exdopodite, and less seate on the U3 endopodite ( Hou & Li, 2005; Figs. 1–5 ).

Comparison of cuticular ultra-structures shows strict differences between G. zagrosensis and the three studied species. Previous studies have exclusively reported L-type pore arrangement for G. bakhteyaricus, Stype for G. lordeganensis ( Khalaji-Pirbalouty & Sari, 2004) , and also S-type for G. balutchi (Khalaji- Pirbalouty & Sari, 2006), while the new species shows both types of pore arrangements on head capsule. On the other hand, the densities of pore distribution in G. lordeganensis and G. bakhteyaricus have been reported to be 18–20 and 45–50 per 25 µm2, while they are found in much higher densities (62–80 in L-type and 75–244 in S-type) in G. zagrosensis .

Figures

FIGURE 1. Map of sampling area of the western part of Zohre River catchments area, Sepidan County, Fars Province. Sampling sites (all springs): Cheshme Owsip (1); Vezge-Morad (2); Khani Varg (3); Baraghan (4); Shesh-Peer (5).

FIGURE 2. Gammarus zagrosensis n. sp., 3, 17.4 mm. A (HC), B (A 1), and C (A 2) on scale i; D (Mn) and E (MnPl) on scale ii, F (exopodite of Maxilipede), G (left palp of maxilla 1), and H (right palp of maxilla 1) on scale iii, and I (T) on scale iv.

FIGURE 3. Gammarus zagrosensis n. sp., 3, 17.4 mm. A (G 1) and B (G 2) on scale i, C (P 3) and D (P 4) on scale ii.

FIGURE 4. Gammarus zagrosensis n. sp., 3, 17.4 mm. A (P 5), B (P 6), and C (P 7), Ci and Cii (bases of P 7 in two paratypes) on scale i; D (US) and E (EP) on scale ii; F (U 3) on scale iii.

FIGURE 5. Gammarus zagrosensis n. sp., Ƥ, 12 mm. A (basis of P 5), B (basis of P 6), C (basis of P 7) and E (oostegite 1) on scale i; D (EP) on scale ii.

FIGURE 6. SEM photographs of head region in Gammarus zagrosensis n. sp. (Right), and G. sepidannus n. sp. (Left).