Niphargus quimperensis Citoleux, Flot & Stoch, 2024

Niphargus quimperensis Citoleux, Flot & Stoch sp. nov.

ZooBank LSID: https://zoobank.org/ urn:lsid:zoobank.org:pub:EF22E055-A6B9-4630-A5EE-E0D191A0815B Etymology: The species is dedicated to the town of Quimper ( Finistère , Brittany, France), in the vicinity of the two peat bogs where it was first found.

Type locality: Tourbière de Creac’h Guen , Quimper, Brittany, France (WGS 84 coordinates: 4.0903473° W, 47.9669393° N) GoogleMaps .

Type material: Holotype (male 2.5 mm), 13.06.2013, leg. J. Citoleaux . Paratypes, four females, same locality and collection date. Appendages of holotype and a female paratype were dissected and mounted on microscopic slides in glycerine, coverslips sealed with epoxy resin, and other paratypes preserved in 75% EtOH with 10% glycerine added. Type material is deposited in the Muséum national d’Histoire naturelle in Paris.

Other materials examined (all coordinates reported in Supporting information, Table S1): Finistère , Brittany, France (leg. J.Citoleaux): Tourbiére de Toulven, Quimper, 26/03/14; Puits Toulalan, Ouessant, 19/05/14; Tourbière de Mougau, Commana, 13/03/17; well of Sainte-Marie du Ménez Hom, Ménez Hom, 17/03/17. Other sites in Brittany, France (leg. D. Weber): Sainte Apolline, Campénéac, Morbihan, 05/07/19, 1 spec.; FontaineLavoir Saint-Brieuc, Cruguel, Morbihan, 07/07/19, 1 spec.; Fontaine de la Trinité, Calan, Morbihan, 09/07/19; Fontaine Saint Julien, Kerloquet , Finistère, 10/07/19, 1 spec.; Fontaine Lavoir Hent Sant Kaourintin, Saint-Connan, Côtes-d’Armor, 11/07/19, 1 spec.; Lavoir Kergrist-Moelou, Kergrist-Molelou, Côtes-d’Armor, 13/07/19, 1 spec.; Source 1 Saint Victor, Kerguinen, Finistère, 13/07/19, 1 spec.; Source à Ty Meur, Traou Don, Finistère, 15/07/19, 3 spec.; Source 1 Saint Victor, Kerguinen, Côtes-d’Armor, 16/07/19, 1 spec.; Source 2 Saint Victor, Kerguinen, Côtes-d’Armor, 16/07/19, 1 spec.; Feunteun ar zant, Saint Rivoal, Finistère, 17/07/19, 1 spec.

Diagnosis: Small niphargid (body length up to 2.5–2.6 mm). First article of mandibulary palp without setae; second article with 2 setae; distal article bearing a single A seta located on outer margin and 5–7 E setae; comb-like D setae absent; a notsclerotized pouch bearing several small setules is present instead of A and B setae. Gnathopod propodites with convex, slightly inclined palm; palmar corner with a single elongated strong spine. Dactylopodite bearing 1 seta along anterior margin. Telson lobes bearing 4 apical spines; lateral margin with 2 plumose setae; dorsal surface smooth. Epimeral plate I with 1 ventral and 2 posterior spiniform setae; plate III with postero-ventral corner not produced. One short spine present near insertion of uropod I. Uropod I rami subequal in female, exopodite length 85% than endopodite length in male. Uropod III short in both sexes; endopodite stout, as long as wide; exopodite 2-articulated, distal article very short.

Description of male holotype and female paratype: Habitus in Figure 7 View Figure 7 > (for comparison habitus of Niphargellus glenniei and Niphargus irlandicus reported in Fig. 12A, B View Figure 12 , field emission scanning electron microscope photographs). Body length 2.5 mm (male) and 2.6 mm (female). Head length 10% of body length; rostrum absent. Pereonites I–VI with 2–3 small dorso-medial sensorial setae, pereonite VII with 4 small dorso-medial sensorial setae. Pleonites I–III with 1–3 small dorsal sensorial setae ( Fig. 11A View Figure 11 ).

Antenna I ( Fig. 8A View Figure 8 ). 46% of body length. Flagellum of 12 articles; articles bearing 1 aesthetasc, its length more than one half of article length; aesthetascs accompanied by 4–6 setae. Distal article shorter than the aesthetasc of penultimate article, bearing 6 distal setae and a short aesthetasc. Peduncle article triarticulated ( Fig. 8A View Figure 8 ), proportions of articles length 1:2:3 as 1.0:0.8:0.5. Accessory flagellum biarticulated ( Fig. 8B View Figure 8 ); proximal article bearing 3 distal setae; distal article as long as one third of proximal article, bearing 2 setae and a short aesthetasc.

Antenna II ( Fig. 8C View Figure 8 ) as long as one third of antenna I. Flagellum of antenna II with 5 articles; each article with 5–7 setae and one sensillum; distal article bearing 4 distal setae accompanied by 1 aesthetasc. Peduncle with proportions of articles length 1:2:3 as 1.0:4.0:4.0; articles 2 and 3 slender; flagellum 70% of peduncle length.

Labium ( Fig. 8D View Figure 8 ) with short inner lobes, without setae. Outer lobes bearing one subapical row of fine setae on inner sides.

Labrum ( Fig. 8E View Figure 8 ) typical of the genus, sub-ovoid in shape.

Mandible ( Fig. 8F, G View Figure 8 ). Right mandible ( Fig. 8F View Figure 8 ): incisor process with 4 teeth, lacinia mobilis with 2 teeth; between lacinia mobilis and pars molaris a row of 5 setae is present; long seta accompanying pars molaris present (truncated in figure); 3 small spines accompanying pars molaris present. Left mandible ( Fig. 8G View Figure 8 ): incisor process with 4 teeth, lacinia mobilis with 2 teeth, one of them pluritoothed; between lacinia mobilis and pars molaris a row of 3 setae is present. Proportions of mandibular palp articles ( Fig. 8G View Figure 8 ) 1:2:3 as 1.0:3.0:2.4. Proximal palp article without setae; second article with 2 setae; distal article with 5–7 E setae ( Fig. 8G, H View Figure 8 ); comb-like D setae absent; a single A seta is present, shifted to the outer margin. An unsclerotized pouch bearing several small setules is present, instead of A and B setae ( Fig. 8H View Figure 8 ). This unusual feature is present in Niphargellus glenniei and Niphargus irlandicus as well ( Fig. 12C, D View Figure 12 ; FESEM photographs), and it was never described in other niphargids. Unfortunately, the material at our disposition did not allow the examination of the setule pouch of Niphargus quimperensis using FESEM because the cuticle shrank during dehydration, but the structure is well evident in the observation using the compound microscope equipped with DIC.

Maxilla I ( Fig. 8I View Figure 8 ). Palp articles 1 and 2 ratio 1:3, with distal article bearing 6 thicker apical setae and several outer setae on the surface. Outer lobe with 6 spines with 1–2 small teeth and one spine with several, small teeth; a group of 6 facial setae is present. Inner lobe elongated (3 times longer than wide), with 4 inner setae and a single, long distal seta.

Maxilla II ( Fig. 8J View Figure 8 ) inner lobe 0.8 times as long as outer lobe; both of them with the apical and subapical setae as usual in the genus, accompanied by several, sparse facial setae.

Maxilliped ( Fig. 8K View Figure 8 ). Palp distal article with 2 very welldeveloped setae close to the insertion of nail. Outer lobe with 2 strong setae and 7 flattened, thick spines. Inner lobe bearing 5 apical setae. Numerous sparse setae are present on the lobes, as in Figure 8K View Figure 8 .

Gnathopod I ( Fig. 9A View Figure 9 ). Coxa 1.75 times wider than long, with 1 long marginal seta. Basipodite 2.3 times longer than wide, bearing 3 long setae on posterior margin; ischiopodite with 2 posterior setae, meropodite bearing a postero-distal group of 7 setae; carpopodite with a continuous row of setae of variable length on posterior margin, and only one seta on anterior margin. Propodite smaller and narrower than in gnathopod 2, with convex, only slightly inclined palm, bearing along anterior margin 3 small groups of 2–3 setae each; posterior margin usually with a single seta; a row of 5 facial setae close to the insertion of palmar spine present both on inner and outer face; antero-distal group of 4 setae close to the insertion of dactylopodite. Palmar corner with a single strong elongated spine. Dactylopodite bearing 1 seta along anterior margin; distal nail as long as one half of dactylopodite, bearing a subungueal seta.

Gnathopod II ( Fig. 9B, C View Figure 9 ). Coxa suboval, with three slender posterior setae. Gill (epipodite) as long as basipodite. Oostegite in females as long as gill. Basipodite elongated, 2.5 times longer than wide; ischiopodite, meropodite, and carpopodite shape and setation similar to gnathopod 1 ( Fig. 9B View Figure 9 ). Propodite 1.2 times longer than wide; palm convex ( Fig. 9B, C View Figure 9 ) identical in both sexes, bearing along posterior margin 4 dense rows of setae; anterior margin with a single row of 3 setae, and a row of 4 setae close to the insertion of palmar spine; antero-distal group of 3–4 setae close to the insertion of dactylopodite. Palmar corner with a strong spine not accompanied by smaller spines. Dactylopodite bearing 1 seta along dorsal margin; distal nail as long as one third of dactylopodite; distal nail accompanied by a subungueal seta.

Pereopods III–IV ( Fig. 9D, E View Figure 9 ). Pereopods III and IV approximately subequal, shape and setation as in Figure 9 View Figure 9 . Gills as long as basipodite, elongated. Dactylopodites III–IV with a single dorsal plumose seta, and one short seta on ventral side, close to the insertion of nail.

Pereopods V–VII ( Fig. 10 View Figure 10 ). Proportions of pereopods V:VI:VII as 1.0:1.2:1.2, shape and setation as in Figure 10 View Figure 10 . Coxae narrow and elongate; coxa VII small, 3 times wider than long, with 2 marginal setae. Gills (epipodites) on pereopod V and VI as long as coxal width. Basipodites V–VII, with slightly concave posterior margins, without distal lobes; posterior margins with 4–7 short setae; anterior margins with setae only. Ischiopodites V–VII with a marked notch. Dactylopodites V–VII with nails length about one third of total dactylus length; dorsal margins with a single plumose seta; ventral margin bearing a distal spine inserted near nail insertion.

Pleopods ( Fig.11B View Figure 11 ). PleopodsI–IIIprotopodites (peduncles) with 2 hooked retinacles. Rami (exopods and endopods) of 6 articles with 2 long setae each.

Uropods ( Fig. 11D–G View Figure 11 ). Uropod I ( Fig. 11D View Figure 11 ) protopodite with no dorsal spines and 1 distal spine close to the insertion of exopodite; length ratio endopodite:exopodite as 1.00: 0.85 in male, subequal in female; rami quite straight; endopodite with 5 terminal spines, exopodite with 5 terminal spines. Uropod II ( Fig. 11E View Figure 11 ) protopodite with 1 dorsal spine; endopodite: exopodite length as 1.0:0.8, both rami bearing 5 stout terminal spines. Uropod III ( Fig. 11F, G View Figure 11 ) short; protopodite without lateral setae or spines, 7–8 apical spines close to the insertion of exopodite; endopodite stout (as long as wide), with 1 lateral seta and 1 apical spine; exopodite 2-articulated, distal article very short; proximal article with 5 groups of stout spines; distal article with 1 stout spine and 1 tiny seta apically.

Telson ( Fig. 11H View Figure 11 ). Telson 1.5 times longer than wide, cleft 75% of length; lobes bearing 4 apical spines; lateral margin with 2 plumose setae; dorsal surface with no setae.

Epimeral plates ( Fig. 11C View Figure 11 ). Epimeral plate I with 1 ventral and 2 posterior spiniform setae; plate II and III with 2 strong setae along ventral margin and 2 posterior setae; plate III with posterior ventral corner not produced.

Urosomites II and III ( Fig. 11A View Figure 11 ) with 2–3 dorso-lateral setae. One short spine present near insertion of uropod I.

A single ovigerous female was found; habitus in Figure 7B View Figure 7 . Brood pouch containing 4 eggs.