identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
2E4787FF62080C68FF05FB59FCF69B16.text	2E4787FF62080C68FF05FB59FCF69B16.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Gammarus arasensis Baytaşoğlu & Özbek & Aksu 2025	<div><p>Gammarus arasensis sp. nov.</p><p>urn:lsid:zoobank.org:act: 744736DA-D19C-485A-B108-9B7DC43AE40B</p><p>(Figs. 2–7)</p><p>Holotype: <a href="https://tb.plazi.org/GgServer/search?materialsCitation.longitude=41.88369&amp;materialsCitation.latitude=39.96912" title="Search Plazi for locations around (long 41.88369/lat 39.96912)">Male</a>, 12, 5 mm. (RTEÜ-FFR20002) Erzurum Province, Türkiye (39.969121 N 41.883690 E); collected by H. Baytaşoğlu.</p><p>Paratypes: 24 males and 12 females, same data as the holotype</p><p>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)</p><p>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.</p><p>Description of male holotype</p><p>Head: Eyes kidney-shaped; slightly shorter than the diameter of the first peduncle segment of antenna 1 (Fig. 2).</p><p>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.</p><p>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.</p><p>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).</p><p>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.</p><p>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</p><p>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).</p><p>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).</p><p>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).</p><p>Pereopod 7: Basis has 10 setules along its concave posterior margin; its anterior margin with 5 small spines in addition to a group of anterodistal spines; inner surface without setae; posterodistal corner bears a seta in the inner part; Ischium, propodus and dactylus are similar to that of pereopod 6 in terms of shape and armament; Merus and Carpus have no setae on both margins; both of them have two groups of spines along their posterior margins while they bear three and four spine groups along their anterior margins, respectively (Fig. 6C).</p><p>Uropod 1: The peduncle is longer than the rami (the length ratio is about 1.0.66) and has 2 small spines at the base; two and five spines occur along the inner and outer margins, respectively; inner ramus with 2 spines on the outer margin and no spine on the inner margin; outer ramus bears two spines on both margins; both rami have 5 distal spines (Fig. 5C).</p><p>Uropod 2: Uropod 2 is smaller than the first one; the length ratio is about 1:0.7; the peduncle segment is as long as the outer ramus; it bears a spine in both distal corners in addition to a spine along the inner margin; the inner ramus is slightly shorter than the outer one; both rami have a just spine along their margins and bears 5 distal spines (Fig. 5D).</p><p>Uropod 3: The peduncle segment is much shorter than the two-articulated outer ramus and the length ratio is about 1:0.37; the length ratio of the inner/outer ramus is about 1:0.63; the inner ramus bears both simple and plumose setae on both margins while there are only simple setae in the distal tip; it bears two spines along the outer margin; outer ramus with plumose setae along the inner margin, its outer margin bears 4 groups of spines accompanying with longer simple setae groups; the second article is longer than the surrounding spines and has long simple setae (Fig. 5E).</p><p>Urosomites: Not elevated. Each segment bears one median and two dorsolateral groups of armaments; each consists of 1–2 spines and 1–3 accompanying short setae.</p><p>Epimeral plates and Pleopods: Epimeral plate 1 (Fig. 5F) is slightly pointed in the postero distal corner and bears 8–9 long setae along the anteroventral margin, no spine is present; pleopod 1–3 are similar to each other in terms of shape and setation; each one bears 2 retinacula (Figs. 5F, G, H); Epimeral plate 2 moderately pointed; the ventral margin is armed with 3 spines, and the posterior margin with 2–3 setae (Fig. 5G); Epimeral plate 3 slightly pointed at the posterior corner and bears 4 spines along the ventral side (Fig. 5H).</p><p>Telson: Telson lobes cleft, each lobe bears 2–3 groups of setae on its outer surfaces in addition to 2–3 spines accompanied by 2–3 setae in their distal part. The length/width ratio of each lobe is about 1:0.45 (Fig. 5I).</p><p>Molecular data analyses</p><p>The genetic distances based on COI ranged from 5.24% (between Gammarus stankokaramani Karaman, 1976 and Gammarus salemaai Karaman, 1985) to 28.10% (between Gammarus pljakici Karaman, 1964 and Gammarus komareki Schaferna, 1923 (Iranian population). The species most closely related to Gammarus arasensis sp. nov. is Gammarus kischineffensis Schellenberg, 1937, with a genetic distance of 16.23%. This value is approximately three times greater than the minimum genetic distance observed (5.24%). For the 28S, pairwise genetic distances ranged from 0.11% (between Gammarus halilicae Karaman, 1969 and Gammarus pljakici) to 7.21% (between Gammarus roeselii Gervais, 1835 and Gammarus stojicevici (Karaman, 1929)). Gammarus kischineffensis again appeared as the species most closely related to Gammarus arasensis sp. nov., with a genetic distance of 1.44%, which is approximately thirteen times greater than the minimum genetic distance observed (0.11%). All interspecific genetic distance values are provided in Table S1 (Supplementary Material).</p><p>Phylogenies constructed using ML and BI have largely been similar topologies. In both topologies, the closest taxon of Gammarus arasensis sp. nov., is Gammarus kischineffensis . Gammarus arasensis sp. nov. was resolved from the closest clade with strong support (0.92) in the BI analysis but remained unresolved with weak support (45%) in the ML analysis. The new species has high branch support (ML: 100%; BI: 1.0) in phylogenies constructed by both methods and is monophyletic (Figure 9). G. arasensis sp. nov. indicates a new lineage phylogenetically distinct from its congeners.According to the ASAP result, 22 MOTUs belonging to 22 species were determined. The best ASAP score was 1.5 (p = 0.01), with a threshold distance of 0.079053. Using the PTP method, 23 MOTUs were identified among the 22 species. The analysis yielded a p -value of 0.001, with a Null-model score of 51.953957. The best score under the single coalescent rate was 56.081402. Notably, Gammarus arasensis sp. nov. was identified as a distinct MOTU separate from other species in both methods.</p></div>	https://treatment.plazi.org/id/2E4787FF62080C68FF05FB59FCF69B16	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		MagnoliaPress via Plazi	Baytaşoğlu, Hazel;Özbek, Murat;Aksu, İsmail	Baytaşoğlu, Hazel, Özbek, Murat, Aksu, İsmail (2025): Morpho-molecular studies suggest a new species from a transboundary river of Turkiye: Gammarus arasensis sp. nov. (Amphipoda: Gammaridae). Zootaxa 5737 (2): 235-253, DOI: 10.11646/zootaxa.5737.2.4, URL: https://doi.org/10.11646/zootaxa.5737.2.4
