Niphargus palatinensis Weber & Brad, 2025

Niphargus palatinensis Weber & Brad sp. nov.

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Figs 12–20 View Fig View Fig View Fig View Fig View Fig View Fig View Fig View Fig View Fig

Diagnosis

Medium-sized Niphargus species, poorly setose. Right postero-ventral angle of epimeral plates. Six spines of maxilla I outer lobe with 1–3 teeth each; 1 spine with several smaller teeth. Mandibular palp with small number (1–2) of B setae. Gnathopods with 1 seta along outer margin of dactylopodites. Pereiopod VII, the longest leg, almost half of total body length. Pleopods retinaculum with 3 hooks. Uropod I, longer exopodite. Uropod II, longer endopodite. Uropod III sexually dimorphic, exopodite elongated in males. Telson with 4 apical spines on each lobe. The COI marker shows six pure diagnostic sites at positions 31 (C), 184 (C), 223 (G), 353 (G), 358 (G) and 391 (A). A single 28S rDNA allele is diagnostic as well as 21 COI barcodes.

Etymology

The species name derives from the German Federal State of Rhineland-Palatinate, where the type locality is located. In Weber et al. (2023), this species was treated as N. aquilex A.

Material examined

Holotype

GERMANY • ♂; Rhineland-Palatinate, Waldleiningen, Felsenbrunnen in the Palatinate Forest in the Middle Buntsandstein; rheocrene spring ; 49.2881° N, 7.8467° E; 14 Dec. 2016; Dieter Weber leg.; kept intact in 96% ethanol; 161214-02; MNHNL130574 . GoogleMaps

Paratypes

GERMANY • 1 ♂; same collection data as for holotype; 14 Dec. 2016; dissected and appendages drawn; 161214-01; ISER microscope slide DW161214-01 • 1 ♀; same collection data as for holotype; 8 Aug. 2017; dissected and appendages drawn; 170808-13; ISER microscope slide DW170808-13 .

Molecular data

COI and 28S rDNA sequences of specimens belonging to Niphargus palatinensis sp. nov. were deposited in GenBank. COI and 28S rRNA accession numbers are present in Supp. file 6 and Supp. file 9, respectively.

Description (male paratype ISER DW 161214-01)

Measurements

Total body length 6.92 mm ( Fig. 12 View Fig ).

Head

Head ( Fig. 12 View Fig ) 8% of total body length. Eyes and rostrum absent.

Antennae

Antenna I ( Fig. 13A View Fig ): with main flagellum formed of 20 articles, representing 50% of total body length. Peduncle length 35% of total length of antenna I. The accessory flagellum ( Fig. 13B View Fig ). Biarticulated; proximal article shorter than first article of main flagellum; distal article 27% of total length of accessory flagellum, with 4 apical setae of different lengths and 1 aesthetasc. Aesthetascs ¾ of respective main flagellum articles ( Fig. 13C View Fig ).

Antenna II ( Fig. 13D View Fig ): flagellum formed of 10 articles and representing 50% of total length of antenna II. Most flagellum articles bear 1 aesthetasc, longer than half of respective flagellum articles.

Mouthparts

Labrum ( Fig. 14A View Fig ): typical, subovoid shape. Labium ( Fig. 14B View Fig ). Large inner lobes with 1 row of fine setae on inner sides. Outer lobes with 2 rows of fine setae subapically on inner sides.

Maxilla I ( Fig. 14C View Fig ): with 3 apical setae on distal article of palp. 6 spines of outer lobe with 1–3 teeth each and 1 spine with several small teeth. Inner lobe with 1 apical seta.

Maxilla II ( Fig. 14D View Fig ): with inner lobe slightly shorter than outer lobe. 1 apical row of setae and 4 setae on inner margin of each lobe.

Left mandible ( Fig. 14E View Fig ): 6 teeth on incisor process. 5 teeth on lacinia mobilis. 8 serrated setae intercalated with 4 trifid setae, between lacinia mobilis and molar process.

Right mandible ( Fig. 14F View Fig ): 5 teeth on incisor process. Lacinia mobilis with several smaller teeth. 7 serrated and 2 trifid setae between lacinia mobilis and molar process. A long seta on molar process.

Mandibular palps ( Fig. 14E–F View Fig ): highly similar and of same length. 3 articles account for 17% (article 1), 39% (article 2) and 44% (article 3) of total length of palp. Proximal article without setae, median article with 8 ventral setae. Distal article of palp with one group of 3 A setae, three groups with 1 B setae, 17 D setae and 5–6 E setae.

Maxilliped ( Fig. 15A View Fig ): with palp formed of 4 articles. Article 1 with 2 setae on inner margin. Article 2 with 23 setae aligned along inner margin. Article 3 with 4 apical setae, one group of 6 dorsal setae and one group of 7 setae on inner margin. Article 4 with 1 seta located on outer margin and 2 fine setae at nail insertion. Outer lobe with 5 apical setae and 9 flattened setae on inner margin. Inner lobe provided apically with 3 setae, 1 flattened seta and 2 dorsal setae.

Gnathopods

Gnathopod I ( Fig. 15B View Fig ): coxal plate in shape of rectangular trapezoid, with depth larger than width (ratio depth: width 1.0: 0.64). Basis length: width ratio 1.0: 0.44. Ischiopodite with one posteroventral group of 3 setae. Basis: carpus length ratio 1.0: 0.58. Carpus with row of 7 setae along ventral margin, group of 5 setae located anterodorsally and one group of 8 setae on carpus surface close to ventral margin. Propodite as long as wide, three groups of 3–4 setae on ventral margin, one group of 4 setae on dorsal margin, one group of 10 anteroapical setae, 3 mesial setae on lateral surface, and one group of 3 setae close to palmar corner. 1 strong palmar spine, 1 supporting spine and 2 denticulate spines present in palmar corner. Dactylopodite with claw 26% of te total dactylopodite length and 1 seta along outer margin.

Gnathopod II ( Fig. 15C View Fig ): slightly larger than gnathopod I, with coxal plate in shape of trapezoid; coxal plate width larger than depth (ratio width:depth 1.0: 0.7). Basis length: width ratio 1.0:0.31. Ischiopodite with one posteroventral group of 4 setae. Basis: carpus length ratio 1.0:0.54. Carpus with row of 6 setae along ventral margin, group of 4 setae located anterodorsally and 1 row of 4 setae on carpus surface close to ventral margin. Propodite as long as wide, with 5 groups of 3 setae on ventral margin, 4 setae on dorsal margin, 1 mesial seta on lateral surface, 8 anteroapical setae, one group of 5 setae on lateral surface close to ventral margin, and 3 setae close to palmar corner. 1 strong palmar spine, 1 supporting spine and 2 denticulate spines present in palmar corner. Dactylopodite with claw 28% of total dactylopodite length and 1 seta along outer margin.

Pereopods

Pereopod III ( Fig. 16A View Fig ): coxal plate in shape of rectangular, with width larger than depth, width: depth ratio 0.7. Propodite: dactylus length ratio 1.0: 0.45. Dactylus, with nail measuring half of total length of dactylus, 1 dorsal seta with plumose tip, and 1 seta at nail base. Pereopod III nearly equal to pereopod IV (pereopod III: pereopod IV length ratio 1.0: 0.98).

Pereopod IV ( Fig. 16B View Fig ): relatively rectangular coxal plate, with concavity on posterior margin, width: depth ratio 1.0: 0.7. Propodite: dactylus length ratio 1.0: 0.54. Robust dactylus, with nail half of total length of dactylus; 1 dorsal seta with plumose tip and 1 seta at nail base.

Pereopod V ( Fig. 17A View Fig ): coxal plate of irregular shape, with deep concavity on ventral side, 4 anterior setae and 1 posterior seta. Basis rectangular, length: width ratio 1.0: 0.57, 4 setae on anterior margin, 9 setae on posterior margin, 3 anteroapical setae of different lengths. Dactylus with 1 dorsal seta with plumose tip, 1 seta at nail base, which represents 45% of total dactylus length. Propodite length: dactylus length ratio 1.0:0.36.

Pereopod VI ( Fig. 17B View Fig ): coxal plate smaller than that of pereopod V, with concavity on ventral side less deep than that of pereopod V, and 1 posterior seta. Basis rectangular, length:width ratio 1.0: 0.55, 4 setae on anterior margin, 8 setae on posterior margin, 2 anteroapical setae. Dactylus with 1 plumose seta on outer margin and 2 setae of different lengths near nail base. Nail 36% of total dactylus length. Ratio propodite: dactylus length 1.0: 0.33.

Pereopod VII ( Fig. 17C View Fig ): longest leg ( 3.22 mm) of inspected paratype male. Coxal plate trapezoidal, with 1 seta on posterior margin. Basis rectangular, ratio length: width 1.0: 0.5, 3 setae on anterior margin, 14 setae on posterior margin and 2 small anteroapical setae. Dactylus with 1 plumose seta on outer margin and 2 setae near nail base. Nail length 31% of total dactylus length. Ratio propodite: dactylus length 1.0: 0.3.

Pereopods V: VI: VII ratio 1.0: 1.35: 1.42.

Pleopods

Pleopods. Similar (pleopod III depicted in Fig. 18A View Fig ), with unequal rami and 3 hooks on retinaculum.

Epimeral plates ( Fig. 18B View Fig )

Epimeral plate I with right postero-ventral angle, relatively straight ventral margin, convex posterior margin with 6 setae. Epimeral plate II with right postero-ventral angle, convex ventral margin with 3 spines, convex posterior margin with 6 setae. Epimeral plate III with right posteroventral angle, convex ventral margin with 3 spines, convex posterior margin with 6 setae.

Uropods

Uropod I ( Fig. 19A View Fig ): with two dorso-lateral rows of 6–8 spines on peduncle. Exopodite slightly longer than endopodite, ratio exopodite: endopodite lengths>plural correct? 1.0: 0.82. 1 strong spine at base of uropod I.

Uropod II ( Fig. 19B View Fig ): with 5 dorsal spines and 1 apical spine on peduncle. Endopodite slightly longer than exopodite, endopodite: exopodite length ratio 1.0: 0.88, both rami provided with 4–6 dorsal and 4 apical spines.

Uropod III ( Fig. 19C View Fig ): sexually differentiated, longer in males. Peduncle with 5 apical, 3 anterior and 1 posterior setae. Endopodite 62% of length of peduncle, with 3 apical setae, 1 subapical and 1 lateral seta on ventral margin. Proximal segment of exopodite shorter than distal segment. Distal: proximal articles length ratio 1.0: 0.93. Anterior margin of proximal segment of exopodite with 6 groups of 1–3 setae (including plumose setae); posterior margin of exopodite with 5 groups of 1–2 setae; 3 antero- and 3 posteroapical setae. Distal segment of exopodite with 4 groups of 2 setae on anterior margin, 4 setae on posterior margin, and 7 apical setae of different lengths.

Telson

Telson ( Fig. 19E View Fig ). Nearly as wide as long (length:width ratio 0.95), with 2 subapical and 4 apical spines of different lengths on each lobe. Longest spine 60% of telson length. 2 thin setae of different lengths and plumose tip on each lobe, 1 seta medially on 1 lobe.

Sexual dimorphism

The examined male and female are highly similar. Besides the usual sexual dimorphism (e.g., slightly smaller gnathopods, presence of oostegites, and slightly deeper coxal plates I– VI in females), in N. palatinensis sp. nov., female uropod III ( Fig. 19D View Fig ) is shorter comparted to that of male. The telson of the inspected female paratype is provided apically with 4 setae on each lobe, and 2 subapical setae on one lobe only ( Fig. 19F View Fig ).

Type locality, ecology and distribution

The species is mainly distributed in the United Kingdom and Western Germany, although two sites from France and one from the Channel Islands ( Guernsey) are known ( Fig. 20 View Fig ). The type locality is the Felsenbrunnen in the Palatinate Forest (community of Waldleiningen, Rhineland-Palatinate, Germany) in the Middle Buntsandstein at 49.2881° N, 7.8467° E (Supp. file 3.4). It is a natural rheocrene with a permanent moderate flow.

The bottom of the spring is covered with sand and rotting foliage above (Supp. file 3.5). With a hardness of 4°GH, the water is very soft. Other species of neither Niphargus nor gammarids were found in this spring. We confirm the permanent presence of this species in the type locality as it was found on 14 December 2016 and 14 June 2019. The species was regularly found in all types of biotopes. Due to the small number of sampling sites, we withstand in providing a more detailed ecological interpretation (Supp. file 4.4).