identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
03E1B6517039706459CAFD4EFCB9FAA2.text	03E1B6517039706459CAFD4EFCB9FAA2.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Gammarus ariegiensis Piscart & Blanchet 2026	<div><p>Gammarus ariegiensis sp. nov.</p><p>Piscart (Figs 3–7)</p><p>Diagnosis</p><p>A rather small species of the Gammarus pulex -group of species with long setae on anterior margin of merus and carpus of pereopods 5–7, a relatively short endopod of uropod 3 which never overreach 50% of the exopod. A2 with short setae as long as or shorter than the diameter of the article, without calceoli.</p><p>Etymology</p><p>The name ariegiensis refers to the name of the French department of Ariège corresponding to the distribution area of the species (see Fig. 1).</p><p>Material examined.</p><p>Holotype</p><p>FRANCE • ♂ (12.8 mm); Moulis, 42°57'17.4"N 1°06'51.4"E; 15 VI 2012; <a href="https://tb.plazi.org/GgServer/search?materialsCitation.longitude=1.1142778&amp;materialsCitation.latitude=42.954834" title="Search Plazi for locations around (long 1.1142778/lat 42.954834)">Ruisseau de la Coumasse</a>; small stream, alt. 630 m; collected from leaf litter by a handnet; MNHN-IU-2023-505 (Muséum national d’Histoire naturelle, Paris, France).</p><p>Paratypes</p><p>FRANCE • 5 ♂♂; same data as for holotype; MNHN-IU-2023-506; • 5 ♀♀; same data as for holotype; MNHNIU-2023-507 .</p><p>Other material examined</p><p>Around 200 specimens from more than 20 locations, France, alt. 200–500m sampled between 15-I-2012 and 15-II-2013.</p><p>Description</p><p>Male: Habitus slender up to 13 mm length. Head with a rounded lateral cephalic lobe (Fig. 3), eyes relatively small, always less than twice as long as wide and widely separated from the mid-dorsal line. The first antenna (Fig. 4A) is slightly longer than the half of the animal body with few setae. The first article of the peduncle is longer than the second article itself two times longer than the third article. The flagellum is more than two times longer than the peduncle with between 25 to 28 articles relatively long. The accessory flagellum has 3–4 articles. The second antenna (Fig. 4B) is always shorter than 2/3 of the first antenna. The gland cone is relatively long and is generally longer the half of the third article of the peduncle. The peduncle article 4 is armed with 3 or 4 groups of setae on all sides as long as or shorter than the diameter of the article. The peduncle article 5 is longer than the peduncle article 4 and armed with five groups of setae as long as or slightly longer than the diameter of the article. The flagellum is relatively short with 9–12 articles and armed with transverse rows of setae slightly longer than articles and decreasing in length on the last articles. Calceoli are always absent.</p><p>The mouthparts are similar to other species from the Gammarus pulex -group (Fig. 4). Right and left maxilla 1 are asymmetric (Fig. 4C), the right palp is wider and has stouter terminal setae than the left one. The inner lobe of the maxilla 1 bears simple setae, and the outer lobe bearing 9 pectinate setae. Palp two articulate, longer than the outer lobe with relatively stout apical setae. Maxilla 2 (Fig. 4D), inner and outer lobes with one row of apical and subapical simple setae. The lateral row of setae is finished on the external face of the inner lobe. The upper and lower lips (Fig. 4E and 4F) are similar to those of the Gammarus with setose inner surface and without inner lobe. The three articles of the mandibular palp are well developed (Fig. 4G). The first article is unarmed and the second is armed with 8–12 long ventral setae. The third article has one row of A-setae, one row of B-setae, an irregular row of 18–22 regular D-setae, and 4–5 long apical E-setae. Mandible incisor 4-touthed (Fig. 4H), lacinia mobilis 2-toothed, followed by a tuft of plumose setae. Molar robust, triturative, with a brush of plumose setae. Maxilliped (Fig. 4I) inner plate ~4x longer than wide, with three tooth-like spines, a spine in the distal corner and long simple setae along the inner margin; distalmost part covered by fine setae in the apical corner. Outer lobe naked on the outer margin. Inner lateral margin bordered by a long row of ~10 knife-like teeth, with the size of teeth increasing progressively towards the apex. Slight variations in the form of the teeth are observed between left and right exopods, the left bearing more spatula-like teeth. First article of palp short, bearing few simple setae at the outer margin. Article 2 long and bearing numerous simple setae (&gt;20) in at the inner margin. Article 3 slightly thinner in proximal part with numerous distalmost setae. Few simple setae on dactylus; the claw is shorter than dactylus.</p><p>Gnathopod 1 carpus is similar in length than the propodus (Fig. 5A), without lateral setae and 4 groups of lateral setae on the ventral margin. The propodus is pyriform with several groups of dorsal and ventral setae, 5 rows of short lateral setae and a sixth group of long setae distally on the outer face. The palm has also a rounded medial palmar spine and several strong and small spines toward the palmar angle, dactylus as long as palm.</p><p>Gnathopod 2 as long as gnathopods 1 but stronger, subchelate (Fig 5B); carpus similar in length than the propodus, with generally 2–3 lateral rows of setae on the outer face. The propodus is pyriform, with 4–5 groups of simple dorsal setae, many ventral setae, and 4 groups of setae on the outer face. The palm is more transverse and stronger than for the first gnathopod and armed with a strong medial palmar spine, a various number of palmar angle spines, dactylus longer than palm width.</p><p>Coxal plates 1–4 have rounded ventral corners, set with sometimes short ventral and lateral setules (Figs. 5A, B and 6A, B). The pereopod 3 (Fig. 6A) slightly longer than pereopod 4 (Fig. 6B). Basis with few but relatively long setae. The carpus, merus and propodus are armed with many groups of setae on posterior margin longer than the diameter of the leg and few spines on the posterior margin of the carpus only. Propodus with 4–5 spines on anterior margin. The dactylus is relatively short with one single seta. The pereopod 4 (Fig. 6B) is similar than pereopod 3 but the setation is reduced both in density and in size.</p><p>Pereopod 5–7 (Fig. 6 C-E) bases expanded with posterior margin convex and minutely serrate, with short setae, posterodistal corner subquadrate on pereopods 5 and 7 but not in pereopod 6; the meri and carpi harbour one of the main characteristics of the species with the presence of setae as long as or longer than spines along the anterior margin. The dactylus and the propodus don’t have setae except at their distal ends with a tuff of relatively long setae and a single long spine. Pereopod 5 (Fig. 6C) has a short subrectangular basis, less than 1.5 times as long as wide without setae on the postero-distal lobe. Pereopod 6 (Fig. 6D) is slightly longer than other pereopods, the basis is two times as long as wide but does not have a backward protruding lobe observed on pereopods 5 and 7. Pereopod 7 (Fig. 6E) is similar to pereopod 6 but basis tapers near the distal half.</p><p>Uropod 1 basis with three long marginal and one terminal spines (Fig. 7A). Endopodite as long as exopodite and armed with 2 lateral spines. Uropod 2 (Fig. 7B) similar to uropod 1 but much shorter. Uropod 3 (Fig. 7C) short, basis with long distal spines; endopodite between 0.4 and 0.5 times the exopodite with simple setae along both margins and plumose setae apically. The exopodite is well developed and armed with few spines and many long simple setae along the outer margin and plumose setae mainly along the inner margin. Pleopods 1–3 (Fig. 7D) are similar in shape with two coupling spines on the basis and very long plumose setae on the flagellum.</p><p>Telson lobes are elongate (Fig. 7E), about twice as long as wide, and as long as the basis of the uropod 3. The armature of lobes consists of 2–3 apical spines and some short dorsal and lateral simple setae.</p><p>The dorsal surface of metasome is unarmed and the urosome segments (Fig. 7F) are flat and armed with 1–2 dorso-distal spines on each side of segments 2 and 3. Sometimes, rare setae are dorsally present on the urosome segments, but always shorter than spines. Epimeral plates (Fig. 7G) with a postero-inferior corner rounded on plate 1 and sub-rectangular on plates 2 and 3. Epimeral plate 1 with relatively long setae along the ventral margin, especially in the antero-distal corner. Epimeral plates 2 and 3 with 3 small spines and few setae on the ventral margin.</p><p>Female: Females slightly shorter than males, maximum size observed 9 mm. The characteristic setation of pereopods 5–7 are also present in females although less developed. Additionally, antenna 2 of females have slightly longer setae than in males. Gnathopod medial palmar spine absent. Uropods 3 similar to those of males.</p><p>Differential diagnosis</p><p>Gammarus ariegiensis sp. nov. is characterized by the presence of long setae on anterior margin of merus, carpus of pereopods 5–7 and the small relative size of the endopod of uropod 3 which never overreach 50% of the exopodite. Among members of the Gammarus pulex -group, only few species share these two characteristics (i.e. G. birsteini, G. orinos, G. rouxi, G. stupendus). However, these species differ from G. ariegiensis sp. nov. by several characteristics (Table 2). The new species differs from all others by the setation pattern of the peduncular flagellum of the second antenna (Table 2), which is less dense and as long as or slightly longer than the width of articles 4 and 5. In addition, G. ariegiensis sp. nov. differs from the two species present in France, G. orinos and G. stupendus, by the presence of plumose setae on the outer margin of uropod 3. Moreover, G. ariegiensis sp. nov. differs from G. orinos by the absence of calceoli on the flagellum of antenna 2 and by the greater length of pereopod 6, which is longer than pereopod 7. Furthermore, it differs from G. birsteini and G. rouxi by the number of apical spines on the telson, and from G. rouxi by the shape and setation of the basal article of pereopod 7.</p><p>Ecology and distribution</p><p>The large-scale sample revealed that the species range is limited to a small fraction of the French Pyrenees between the Hers and the Garonne Rivers (Fig. 1). This covers most of the Ariège administrative department. At the eastern part of its range, another species associated to the G. pulex group is identified, and it seems that the two species may co-occur in a few rivers at the range limits (Fig. 1). In the range area of the species, G. ariegiensis was found in all but one prospected site, indicating a broad tolerance to abiotic conditions. In particular, in these sites (black dots in Fig. 1), pH varied from 7.1 to 8.8, conductivity varied from 56 to 486 µSm. cm-1 and O 2 concentration varied from 8.34 to 11.18 mg.L- 1. It is noteworthy that this sampling was made to optimize the collection of Gammarus specimens, meaning that non-optimal rivers (e.g. high-altitude or acidic rivers) were not considered, which limits the exact definition of the abiotic niche of G. ariegiensis .</p></div>	https://treatment.plazi.org/id/03E1B6517039706459CAFD4EFCB9FAA2	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	Piscart, Christophe;Blanchet, Simon	Piscart, Christophe, Blanchet, Simon (2026): Morphological and genetic differentiations revealed a new freshwater species of Gammarus from the French Pyrenees. Zootaxa 5757 (3): 279-293, DOI: 10.11646/zootaxa.5757.3.5, URL: http://dx.doi.org/10.7717/peerj.20736
