Niphargus normandiensis Weber & Brad sp. nov.

urn:lsid:zoobank.org:act: DA362C5F-406A-4759-B64C-318A1A9E823E

Figs 21–29

Diagnosis

Medium-sized Niphargus species, poorly setose. Right postero-ventral angle of epimeral plates. Six spines of maxilla I outer lobe with 1 tooth 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 dactylopodite. Pereiopod VII, the longest leg, slightly longer than half of total body length. Pleopods retinaculum with 5 hooks. Uropod I, longer exopodite. Uropod II, longer endopodite. Uropod III sexually dimorphic, exopodite elongated in males. Telson with 3 apical spines on each lobe. No pure diagnostic sites are present in the COI marker, but a single 28S rDNA allele as well as six COI barcodes are diagnostic.

Etymology

The species name derives from the French region of Normandy, where the type locality is located. In Weber et al. (2023), this species was treated as N. aquilex D, N.

Material examined

Holotype FRANCE • ♂; Calvados, Carrière souterrain de Saint-Vaast-en-Auge, small lake in a subterranean quarry in sandstone outside the village Saint-Vaast-en-Auge; 49.2910° N, 0.0009° W; 26 May 2018; Dieter Weber leg.; kept intact in 96% ethanol; 180526-43a; MNHNL 130577.

Paratypes

FRANCE • 1 ♂; same collection data as for holotype; 26 May 2018; dissected and appendages drawn; 180526-36; ISER microscope slide DW180526-36 • 1 ♀; same collection data as for holotype; 26 May 2018; dissected and appendages drawn; 180526-31; ISER microscope slide DW180526-31 • 1 ♀; same collection data as for holotype; 26 May 2018; ISER DW180526-32 • 1 ♀; same collection data as for holotype; 26 May 2018; ISER DW180526-33 .

Molecular data

COI and 28S rDNA sequences of specimens belonging to Niphargus normandiensis 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 180526-36)

Measurements

Total body length is 7.54 mm (Fig. 21).

Head

Head (Fig. 21) 7.3% of total body length. Eyes and rostrum absent.

Antennae

Antenna I (Fig. 22A): with main flagellum formed of 17 articles, representing 55% of total body length. Peduncle length 40% of total length of antenna I. Accessory flagellum (Fig. 22B) biarticulated; proximal article slightly longer than first article of main flagellum; distal article 28% of total length of accessory flagellum, with 3 apical setae of different lengths and 1 aesthetasc. Aesthetascs ⅓ of respective main flagellum articles (Fig. 22C).

Antenna II (Fig. 22D): flagellum formed of 8 articles and representing 42% of total length of antenna II. Most flagellum articles bear 1 aesthetasc, ¼ length of respective flagellum articles.

Mouthparts

Labrum (Fig. 23A): typical, subovoid shape. Labium (Fig. 23B). Large inner lobes with 1 row of fine setae on inner sides. Outer lobes with 1 row of fine setae subapically on inner sides.

Maxilla I (Fig. 23C): with 3 apical setae on distal article of palp. Six spines of outer lobe with 1 tooth each and 1 spine with several small teeth. Inner lobe with 1 apical seta.

Maxilla II (Fig. 23D): with inner lobe slightly shorter than outer lobe. 1 apical row of setae on each lobe.

Left mandible (Fig. 23E): 5 teeth on incisor process. 3 teeth on lacinia mobilis. 10 serrated setae between lacinia mobilis and molar process.

Right mandible (Fig. 23F): 4 teeth on incisor process. 2 teeth on lacinia mobilis. 5 serrated setae between lacinia mobilis and molar process. Long seta on molar process.

Mandibular palps (Fig. 23E–F): highly similar and of same length. 3 articles account for 18% (article 1), 36% (article 2) and 46% (article 3) of total length of palp. Proximal article without setae, median article with 6–7 ventral setae. Distal article of palp with one group of 5 A setae, four groups with 1 B setae each, 22–23D setae and 6 E setae.

Maxilliped (Fig. 24A): with palp formed of 4 articles. Article 1 asetose. Article 2 with 23 setae aligned along inner margin. Article 3 with 6 apical setae, one group of 6 dorsal setae and one group of 4 setae on inner margin. Article 4 with 1 seta located on outer margin and 2 setae at nail insertion. Outer lobe with 5 apical setae and 8 flattened setae on inner margin. Inner lobe provided apically with 5 setae and 1 flattened seta.

Gnathopods

Gnathopod I (Fig. 24B): coxal plate in shape of rectangular trapezoid, with depth larger than width (ratio depth:width 1.0:0.53). Basis length:width ratio 1.0: 0.64. Ischiopodite with one posteroventral group of 8 setae. Basis: carpus length ratio 1.0: 0.75. Carpus with row of 9 setae of various lengths along ventral margin, group of 3 setae located anterodorsally and one group of 2 setae on carpus surface close to ventral margin. Propodite nearly as long as wide, five groups of 3–4 setae on ventral margin, two groups of 2 setae each on dorsal margin, one group of 5 setae on propodite surface close to dorsal margin, one group of 10 anteroapical setae, 2 mesial setae on lateral surface, 2 setae on lateral surface close to ventral margin 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 30% of total dactylopodite length and 1 seta along outer margin.

Gnathopod II (Fig. 24C): slightly larger than gnathopod I, with coxal plate in shape of trapezoid; coxal plate wider than deep (ratio width:depth 1.0: 0.7). Ovoid gill and of same length as coxal plate width. Basis length: width ratio 1.0:0.38. Ischiopodite with one posteroventral group of 6 setae. Basis: carpus length ratio 1.0: 0.57. Carpus with row of 9 setae of various lengths along ventral margin, group of 6 setae located anterodorsally and 1 row of 5 setae on carpus surface close to ventral margin. Propodite width larger than length (ratio width: length 1.0: 0.94), with 7 groups of 3–5 setae on ventral margin, one group of 6 setae on dorsal margin, one group of 2 setae on lateral surface close to dorsal margin, 1 mesial seta on lateral surface, one anterodorsal group of 8 setae, and one group of 3 long setae in vicinity of palmar corner. 1 strong palmar spine, 1 supporting spine and 3 denticulate spines present in palmar corner. Dactylopodite with claw 30% of total dactylopodite length and 1 seta along outer margin.

Pereopods Pereopod III (Fig. 25A): coxal plate in shape of rectangular trapezoid, wider than deep (ratio width:depth 1.0:0.75). Propodite: dactylus length ratio 1.0: 0.4. Dactylus, with nail measuring half of total length of dactylus, 1 dorsal seta with plumose tip, and 2 setae at nail base. Pereopod III slightly longer than pereopod IV (pereopod III: pereopod IV length ratio 1.0:0.95).

Pereopod IV (Fig. 25B): coxal plate in shape of rectangular trapezoid, width: depth ratio 1.0: 0.68. Propodite:dactylus length ratio 1.0: 0.4. Robust dactylus, with nail measuring almost half of total length of dactylus; 1 dorsal seta with plumose tip and 2 setae of different lengths at nail base.

Pereopod V (Fig. 26A). Shortest leg (2.64 mm) of inspected male paratype. Coxal plate of irregular shape, with deep concavity on ventral side, and 2 anterior setae. Basis rectangular, length: width ratio 1.0: 0.62, 3 setae on anterior margin, 6 setae on posterior margin, 3 anteroapical setae of different lengths. Dactylus with 1 dorsal seta with plumose tip, 2 setae of different lengths at nail base, which representing 42% of total dactylus length. Propodite length: dactylus length ratio 1.0: 0.49.

Pereopod VI (Fig. 26B): coxal plate relatively similar to that of pereopod V, with 1 posterior seta. Basis rectangular, length: width ratio 1.0: 0.58, 4 setae on anterior margin, 10 setae on posterior margin, 3 anteroapical setae of different lengths. Dactylus with 1 plumose seta on outer margin and 2 setae of different lengths near nail base. Nail ⅓ of total dactylus length. Propodite: dactylus length ratio 1.0: 0.42.

Pereopod VII (Fig. 26C): longest leg (3.90 mm) of inspected paratype male. Coxal plate trapezoidal, with 1 seta on posterior margin. Basis rectangular, ratio length: width 1.0: 0.52, 5 setae on anterior margin, 11 setae on posterior margin and 2 anteroapical setae of different lengths. Dactylus with 1 plumose seta on outer margin and 1 seta near nail base. Nail length 35% of total dactylus length. Ratio propodite:dactylus length 1.0: 0.38.

Pereopods V: VI: VII ratio 1.0: 1.31: 1.47.

Pleopods

Pleopods similar (pleopod III depicted in Fig. 27A), with unequal rami and 5 hooks on retinaculum. One of pleopods III laterally with 2 additional hooks on retinaculum.

Epimeral plates (Fig. 27B)

Epimeral plate I with right postero-ventral angle, straight ventral margin, relatively straight posterior margin with 4 setae. Epimeral plate II with right postero-ventral angle, convex ventral margin with 2 spines, convex posterior margin with 3 spines. Epimeral plate III with right posteroventral angle, straight ventral margin with 2 spines, convex posterior margin with 5 spines.

Uropods

Uropod I (Fig. 28A): with two dorso-lateral rows of 3–4 spines on peduncle. Exopodite longer than endopodite, exopodite: endopodite length ratio 1.0: 0.66. 1 strong spine at base of uropod I.

Uropod II (Fig. 28B): with 4 dorsal and 2 apical spines on peduncle. Endopodite longer than exopodite, endopodite: exopodite length ratio 1.0: 0.84, both rami provided with 1–2 dorsal and 5 apical spines.

Uropod III (Fig. 28C) sexually differentiated, longer in males. Peduncle with 4 posteroapical setae. Endopodite 67% of length of peduncle, with 4 small apical setae. Distal segment of exopodite slightly longer than proximal segment (ratio 1.0: 0.95). Anterior margin of proximal segment of exopodite with 3 groups of 3–4 setae; posterior margin of exopodite with 4 groups of 2–4 setae; 1 antero- and 1 posteroapical seta. Distal segment of exopodite with 3 groups of 2 setae on anterior margin, 4 groups of 2 setae on posterior margin, and 8 apical setae of different lengths.

Telson

Telson (Fig. 28E) wide (width:length ratio 1.0: 0.76), with 3 long apical spines, 2 spines and 2 thin setae with plumose tip located medially on each lobe. Longest spine 78% of telson length.

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. normandiensis sp. nov., the female uropod III is shorter comparted to that of the male (Fig. 28D). The female telson is highly similar to that of the male, but smaller (Fig. 28F).

Type locality, ecology and distribution

The species comprises three distinct genetic clades (clade N, D and non-annotated) which are distributed in the Normandy (France), with further scattered records on the Channel Islands (Guernsey, Jersey), on two islands off the Brittany Coast of France and in more Central France (Fig. 29). Thereby, clade D is restricted to Normandy (France), whereas both other clades occur on islands in the Atlantic Ocean and in more Central France. The type locality is the Carrière souterrain de Saint-Vaast-en-Auge, Calvados, France at 49.2910° N, 0.00090° W, a subterranean quarry in sandstone outside the village (Supp. file 3.6). The 50 m long cavity is completely dry with a small lake with stagnant water at 40–45 m distance from the entrance, behind a collapsed mine gallery. The water level varies seasonally from 20–70 cm. Specimens of N. normandiensis sp. nov. were found swimming on the clayey bottom of this lake. We confirm the permanent presence of this species in the type locality as it was found on 26 May 2018 as well as on 20 May 2019. We found this species in several springs and in one subterranean quarry. Ecological details are not inferred due to the small number of sampling sites.