Niphargus lourensis, Fišer & Trontelj & Sket, 2006

Fišer, Cene, Trontelj, Peter & Sket, Boris, 2006, Phylogenetic analysis of the Niphargus orcinus species- aggregate (Crustacea: Amphipoda: Niphargidae) with description of new taxa, Journal of Natural History (J. Nat. Hist.) 40 (41 - 43), pp. 2265-2315 : 2288-2294

Niphargus lourensis n. sp. ( Figures 7 , 16–19 )

Type locality. Spring of Louros River , Vouliasta , Ionannina , Greece.

Material examined. Spring of Louros River , Vouliasta, Ionannina, Greece; 25 April 2004; coll. C. Fišer and R. Verovnik.

Holotype: female, 15 mm; slide no. 4.

Another specimen found is preserved in 96% ethanol for molecular analyses and is deposited in the collection of Oddelek za biologijo, Biotehniška fakulteta, Univerza v Ljubljani (Department of Biology, Biotechnical Faculty, University of Ljubljana).

Etymology. The epithet lourensis is derived from the type locality.

Diagnosis

Pleonites I–III with setae along dorso-posterior margin. Telson with apical spines only; these are very long (0.61 telson length). Carpus I–II with postero-proximal bulge large (1/3 of carpus length); gnathopod II propodus large ([length+width+diagonal] 0.29 body length); much larger than propodus of gnathopod I (1:0.75). Denticulated spines in palmar corner of gnathopod II hidden behind the palmar spine. Coxae V–VII with single posterior setae. Pereopods V–VII with numerous strong spines. Uropod III very spiny and very short (0.19 of body length); exopodite flattened, distal article with setae along one margin only.

Description

Head and trunk ( Figures 7 , 18 ). Body length up to 15 mm. Head length 11% of body length; rostrum absent. Pereonites I–VI without setae; pereonite VII with 2 postero-ventral setae.

Pleonites I–III with 6 setae along dorso-posterior margin. Epimeral plate II: angle of postero-ventral corner sub-rectangular; posterior margin concave; ventral margin convex; at the ventral margin 1 spine, along posterior margin 6 setae. Epimeral plate III: angle of postero-ventral corner acute; posterior margin concave; ventral margin convex. Along ventral margin 2 spines; along posterior margin 6 setae.

Urosomite I postero-dorso-laterally with 2 spines; urosomite II postero-dorso-laterally with 4 spines; urosomite III postero-dorso-laterally without setae and/or spines. At the base of uropod I 1 spine.

Telson length:width is 1:0.85; cleft 0.65 of length. Only 3–4 apical telson spines per lobe, they are very long, 0.6 of telson length. Plumose setae inserted laterally in the middle part of telson.

Antennae ( Figure 16 ). Antenna I 0.5–0.55 of body length. Flagellum with 33 articles; each article with 1 aesthetasc. Peduncle articles lengths in ratio 1:0.85:0.55. Proximal article of peduncle dorso-distally slightly produced. Accessory flagellum biarticulated; distal article shorter than half of proximal article length.

Length ratio antenna I:II as 1:0.55. Flagellum of antenna II with 12 articles; aesthetascs absent. Peduncle articles lengths 4:5 is 1:1.05; flagellum 0.65–0.7 of peduncle length (articles 4+5). Article 4 of antenna II peduncle proximally with ventral row of fine setae.

Mouth parts ( Figure 16 ). Inner lobes of labium longer than half of the outer lobes.

Left mandible: incisor with 5 teeth, lacinia mobilis with 4 teeth; a row of serrated spines between lacinia and molar and a long seta at the base of molar. Right mandible: incisor process with 4 teeth, lacinia mobilis with several small denticles, a row of serrated setae and molar process with a long basal seta. Mandibular palp article 2:article 3 (distal) is 1:1.4. Proximal palp article without setae; the second article with 8 setae groups and single setae; distal article with 2 A groups of 1+7 setae; 4 B groups; 41 D single setae; 6 E single setae.

Maxilla I distal palp article with 4 setae apically. Outer lobe of maxilla I with 7 uni-, bi- or pluri-toothed spines; inner lobe with 4 setae.

Maxilla II inner lobe slightly smaller than outer lobe; both of them with numerous apical setae.

Maxilliped palp article 2 with 9 rows of setae along inner margin; distal article with a dorsal seta and a group of small setae at the base of the nail. Outer lobe with 10 flattened spines and 7 serrated setae. Inner lobe with 4 flattened spines and 10 serrated setae apically.

Coxal plates, gills ( Figures 7 , 17–19 ). Coxal plate I of irregularly trapezoid shape; anterior and ventral margin of coxa I with 6 setae. Coxal plate II width:depth is 1:0.88; anterior and ventral margin with 9 setae. Coxal plate III width:depth is 1:0.8; antero-ventral margin with 10 setae. Coxal plate IV width:depth is 1:0.9; posterior concavity slightly developed (concavity depth between 0.1–0.2 coxa width); antero-ventral margin with 10 setae. Coxal plates V–VI with anterior lobe; posterior margin with 1 spine. Coxal plate VII ‘‘half-egg’’ shaped; posterior margin with 1 seta. Gills II–VI large, irregularly ovoid.

Gnathopod I ( Figure 17 ). Ischium with single postero-distal row of setae. Carpus 0.5 of basis length and 0.65 of propodus length. Anterior margin of carpus with distal group of setae only; carpus posteriorly with transverse rows of setae proximally and a row of lateral setae; postero-proximal bulge large (1/3 of carpus length), positioned proximally. Propodus ‘‘hoof’’-shaped, palm long, oblique and convex. Posterior margin with 10 rows of denticulated setae. Anterior margin with 25 setae in 6 groups; antero-distal group with 10 setae. Group of 3 facial setae proximally of palmar spine; small groups of surface setae present. Palmar corner with strong palmar spine, single supporting spine on inner surface and 4 denticulated spines on outer side. Nail length 0.3 of total dactylus length; along anterior margin 3 single setae and a group of 2 setae; short setae along inner margin present.

Gnathopod II ( Figure 17 ). Basis width:length is 1:0.3. Ischium with single postero-distal row of setae. Carpus 0.5 of basis length and 0.6 of propodus length. Anterior margin of carpus with distal group of setae; carpus posteriorly with transverse rows of setae proximally, a row of lateral setae, and a short row of setae at the base medially; posteroproximal bulge large (1/3 of carpus length), positioned proximally. Propodus much larger than propodus I, ‘‘hoof’’-shaped, palm long, oblique and convex. Posterior margin with 12 rows of denticulated setae. Anterior margin with 10 setae in 5 groups; antero-distal group with 12 setae. Group of 3 facial setae proximally of palmar spine; small groups of surface setae present. Palmar corner with strong palmar spine, single supporting spine and 2 denticulated spines on inner surface. Nail length 0.25 of total dactylus length. Along anterior margin 6 single setae; short setae along inner margin present.

Pereopods III–IV ( Figure 18 ). Lengths of pereopods III:IV is 1:0.95. Dactylus IV 0.3 of propodus IV length; nail length 0.5 of total dactylus length. Dactyli III–IV with dorsal plumose seta; at the base of nail a spine and a seta.

Pereopods V–VII ( Figure 19 ). Lengths of pereopods V:VI:VII is 1:1.25:1.25. Pereopod VII length 0.55 of body length.

Bases V–VII length:width is 1:0.65–0. 7; posterior margin convex to straight; posterodistal lobe small; posteriorly 13 (basis V), 12 (basis VI) or 9 (basis VII) setae; anteriorly 8– 9 single and/or groups of slender spines and/or setae. Spines on articles 4–6 of peropods V– VII, numerous, long and strong. Propodus VII:dactylus of pereopod VII is 1:0.2. Dactylus VII with dorsal plumose seta; at the base of nail a strong spine and a seta.

Pleopods and uropods ( Figure 18 ). Pleopods I–III with 2-hooked retinacles each and few setae. Pleopod II rami of 12–14 articles each.

Uropod I protopodite with 7 dorso-lateral spines and 4 dorso-medial spines. Exopodite:endopodite lengths is 1:1; rami straight. Uropod I rami with groups of spines and/or setae along medial and lateral surfaces. Endopodite with 7 setae and/or spines in 5 groups; apically 5 spines. Exopodite with 7 setae and/or spines in 6 groups; apically 5 spines.

Uropod II exopodite:endopodite length is 1:1.1.

Uropod III length is 0.2 of body length. Protopodite with 2 lateral spines and 8 apical spines and/or setae. Endopodite 0.4 of protopodite length; apically with 1 spine and 1 plumose seta; laterally 1 seta. Exopodite of uropod III flattened; distal article 0.15 of proximal article length. Proximal article with 6 groups of setae, plumose setae and very long and strong spines along inner margin; 5 groups of very long and strong spines and setae along outer margin. Distal article of exopodite with 3 lateral groups of setae; groups set along one margin; apically 3 setae.

Variability. Only one female was studied.

Remarks and affinities. The most remarkable features of the species are extremely strong and long spines on telson and appendages as well as setae along the dorso-posterior margins of the pleonites. These characters can be found also in N. podgoricensis , which can be distinguished by the presence of spines on urosomite III and plumose setae on uropod I. Another important distinguishing feature between N. podgoricensis and N. lourensis are proportions of gnathopods and the position of spines on the palmar corner of gnathopod II, which in the new species resembles N. arbiter , N. salonitanus , N. rejici and N. dabarensis . However, none of these taxa has such long telson spines or setae along the dorso-posterior margins of the pleonites.

Figures

Figure 7. N. lourensis sp. n. (above) and N. polymorphus sp. n. (below). Holotypes, lateral view.

Figure 16. Niphargus lourensis sp. n., holotype. Mouthparts.

Figure 17. Niphargus lourensis sp. n., holotype. Gnathopod I (above) and gnathopod II (below).

Figure 18. Niphargus lourensis sp. n., holotype. Pereopods III–IV, detail of pereopod IV dactylus. Uropods I–III. Telson.

Figure 19. Niphargus lourensis sp. n., holotype. Pereopods V–VII. Details of pereopod VII.