Gammarus arasensis Baytaşoğlu, Özbek & Aksu, 2025, sp. nov.
Diğer yayınlar > Diğer · 2025
Yazarlar: Baytaşoğlu, Hazel, Murat ÖZBEK, Aksu, İsmail
Diğer, Uluslararası, 2025,
Özet
Gammarus arasensis sp. nov. urn:lsid:zoobank.org:act: 744736DA-D19C-485A-B108-9B7DC43AE40B (Figs. 2–7) Holotype: Male, 12, 5 mm. (RTEÜ-FFR20002) Erzurum Province, Türkiye (39.969121 N 41.883690 E); collected by H. Baytaşoğlu. Paratypes: 24 males and 12 females, same data as the holotype Genetic material: RTEÜ-FFR-DNA K254, K179, K165 same data as the holotype (GenBank accession numbers: PQ458061, PQ458062, PQ458063 for COI and PQ456280, PQ456281, PQ456282 for 28S, respectively) Diagnosis: Antenna 1 with 17–20 flagellar articles. Antennal gland cone reaching the distal end of peduncular article 3 of antenna 2. Coxae 1–4 with long setae on inner ventral margins. Pereopods 3–4 with short posterior setae. Uropod 3: endopod 0.64 times the length of exopod. Description of male holotype Head: Eyes kidney-shaped; slightly shorter than the diameter of the first peduncle segment of antenna 1 (Fig. 2). Antennae: Antenna 1 (Fig. 4A) is distinctly shorter than half the body length; peduncle segments do not bear long setae; several sets of setae present distally on all three segments; segments gradually decrease in length (ratio: 1:0.75:0.5); flagellum short, bearing 16–17 segments; each flagellum segment bearing a few thin setae distally and an aesthetasc from the second segment; accessory flagellum 3-segmented, the last segment 1/3 the length of the previous one. Antenna 2 (Fig. 4B) slightly shorter than antenna 1 (ratio 1:0.86); antennal gland cone straight, almost reaching the distal end of the third peduncle segment; the last peduncle segment is slightly longer than the previous one (ratio: 1.12:1); the fourth and fifth peduncle segments bear bundles of setae in 3–4 groups in three rows; setae are not longer than the diameter of the peduncle segment; the 10 non-inflated flagellar segments are not densely setose and each has calceoli. Mouthparts: Upper lip (Figure 3A) has many small setules in the distal part; left mandible has 5-toothed incisors and 4-toothed lacina mobilis; between triturative molar and lacina mobilis there are 6–7 finger-like structures; one long plumose seta is present in the base part of the molar; while there is no seta in the first segment of the mandibular palp, there are 8 setae gradually extending distally in the second segment; third segment bears 24 D-seta, 4–5 E-seta, one group A-seta and one group B-seta; C-seta is absent (Figure 3H, H’); right mandible has 4-toothed incisors and multi-toothed lacina mobilis; first and last palp segments, molar and surrounding structures are the same as those in the left mandible; 15 setae are present in the second segment of the palp (Figure 3G, G’); right and left maxilla have 1 asymmetric structure; right maxilla 1 (Figure 3F, F’) bears 13 plumose setae on the distal inner lobe; there are 11 serrated teeth on the distal outer lobe, of which the serrations of the inner lobe side are more numerous and finer; there is no setation on the first segment of the palp; the second segment of the palp is shovel-shaped and bears four thick spines and two setae (one thicker) on the distal side; left maxilla 1 (Figure 3D, D’) inner and outer lobes are similar to the right; the first segment of the palp bears no setae; the second segment is slightly elongated sickle-shaped and bears 8 spines on the distal end; there are no lateral setae on the palp segments of right and left maxilla 1. There is no inner lobe on the lower lip (Figure 3C); it bears numerous tiny distal and disto-lateral setae; maxilla 2 (Figure 3E) the outer lobe is slightly longer than the inner one (ratio: 1:1.1); the convex distal margins of both lobes bear 20–30 and 10–15 simple setae, respectively; similarly, the outer margins of both lobes contain numerous tiny setae; the inner margin of the inner lobe bears 14–15 plumose setae in a diagonal row. Coxal Plates: Coxal plates 1–4 bear one relatively long simple seta located near the anterodistal margin of their inner surfaces (Figs. 1; 4C, D; 5A, B). Coxal plate 1 is rectangular and slightly widened in distal part (length/ width ratio: 1:1.28); it bears 2 and 1 anteriorly and posteriorly positioned setae along the convex ventral margin, respectively (Fig. 4C); coxal plate 2 has a slightly convex margin that is slightly narrowed distally (length/width ratio: 1:1.6); in addition to one long seta on the anterodistal inner surface as in coxal plate 1, it bears 2 short setae anteriorly and 1 posteriorly on the ventral margin (Fig. 4D); coxal plate 3 is rectangular (length/width ratio: 1:1.76) and the ventral margin is convex and bears 2 anterior and 1 posterior distal setae, respectively; there is one long setae on the posterodistal side of the inner surface (Figure 5A); the ventral margin of coxal plate 4 is slightly convex with a length/width ratio of about 1:1.25; there is 1 long setae on the inner surface, located near the anterodistal side; in addition, there are 2 short setae on the anterodistal corner and 4 short setae on the posterior margin (Figure 5B); coxal plate 5 is bilobed and is wider than it is long (length/width ratio: 1:1.83); anterior lobe 1 with very convex margins; the posterior lobe bears 2 short setae (Figure 6A); coxal plate 6 is bilobed, with lobes slightly separated and without very convex margins; The posterior margin of the posterior lobe bears 2 short setae (Fig. 6B); coxal plate 7 is similar in structure to 6 and bears 6 short setae in the posterior part (Fig. 6C). Gnathopods: The basal segment of gnathopod 1 has 5 and 18–20 setae on the anterior and posterior margins, respectively (Fig. 4C); setae along the posterior margin are 1.8 times longer than the segment diameter, and those on the anterior margin are 1.5 times longer; in addition, there are 2 groups of setae on the posterodistal, some of which are more rigid; ischium and merus bear setae distoposteriorly; triangular carpus is slightly shorter than the propodus (ratio: 1:1.38); it has 3 groups of setae on the anterior margin in addition to numerous setae on the distoposterior part; the length/width ratio of the pyriform propodus is 1:0.55; there are two groups of setae on the anterior margin, bearing 2–3 groups of short setae on the inner and outer surfaces; medial palmar spine present; posterodistal angle surrounded by 7–8 small spines and 7–8 long simple setae; sickle-shaped dactylus bears 1 seta on outer margin and barely reaches posterodistal corner. Gnathopod 2 is stronger and more setose than 1; basal segment anterior and posterior margins have 7–8 and 28–30 long setae respectively and the length of the setae on the posterior margin reaches twice the segment diameter; ischium and merus are similar to those of gnathopod 1 in shape and setae; triangular carpus is shorter than propodus (ratio: 1:1.29) and bears two groups of setae along the anterior margin; there are 5 groups of setae in a transverse row on the posterior margin; propodus length/width ratio is around 1:1.65 and bears setae in 4 groups along the anterior margin; there are 7–8 transverse setae groups on the posterior margin and 3–4 setae groups on the inner and outer surfaces; medial palmar spines are present; there are 3 strong spines and a few small spines on the posterodistal corner; The sickle-shaped dactylus extends between the spines at the posterosdital corner and bears a single seta on its outer margin. Pereopod 3: Basal segment of pereopod 3 bears numerous long (up to 1.8 times the segment diameter) setae along its anterior and posterior margins; a group of setae is present on the posterodistal of the ischium; merus bears two groups of spines and setae (and a single short setae) on its anterior margin, while 7 groups of setae are carried along its posterior margin, and the length of these setae can reach 1.5 times the segment diameter; carpus is shorter than merus (ratio: 1:1.41) and has fewer setae; it bears 1 group of spines+seta anterodistally and 4–5 groups of setae along its posterior margin; the lengths of these setae are shorter than those on merus; propodus is almost the same length as carpus, with one group anterodistally and 5–6 groups of armament on its posterior margin; dactylus is about 3 times longer than wide, with 1 plumose seta on outer margin and 2 small setae on inner margin at base of nail (Fig. 5A Pereopod 4: Pereopod 4 is slightly shorter than 3; the shape and setation of basis, ischium, propodus, and dactylus are similar to pereopod 3; the setation on the posterior margins of merus and carpus is shorter and less than that of pereopod 3 (Fig. 5B). Pereopod 5: Basis in rectangular shape and bears 8–9 short setae along the posterior margin; anterior margin with 7–8 small spines in addition to two groups of setae in the proximal part; inner surface with no setae; no spine exists in the postero-ventral corner; Ischium anterodistal corner with 2 spines; merus has two groups of spines in addition to a group of short setae along the anterior margin, posterior margin with two groups of spines; Carpus has three groups of spines both on the anterior and posterior margins; anterior margin of the propodus with 5 pairs of spines while there are two groups of setae along its posterior margin; dactylus with a plumose setule and two simple setules along its outer and inner margins, respectively (Fig. 6A). Pereopod 6: Basis in an elongated rectangular shape; posterior margin of the basal segment is concave and bears 10 setules; anterior margin with 4 small spines in addition to an anterodistal spine group; inner surface without setae; Ischium is similar to that of pereopod 5 in terms of shape and armament; Merus bears two groups of spines in both distal corners in addition to three and a group of spines along the anterior and posterior margins, respectively; Carpus bears no setae on both margins but has four and two groups of spines along its anterior and posterior margins, respectively; Propodus and dactylus are similar to that of pereopod 5 in terms of the armament (Fig. 6B). Pereopod