Niphargus molnari Mehely , 1927

Angyal, Dorottya, Balazs, Gergely, Zaksek, Valerija, Krizsik, Virag & Fiser, Cene, 2015, Redescription of two subterranean amphipods Niphargusmolnari Mehely, 1927 and Niphargusgebhardti Schellenberg, 1934 (Amphipoda, Niphargidae) and their phylogenetic position, ZooKeys 509, pp. 53-85 : 57-64

Taxon classification Animalia Amphipoda Niphargidae

Niphargus molnari Mehely, 1927

Niphargus molnari sp. n.: Méhely 1927 type locality: Mánfai-kőlyuk Cave; Data from the original description is available in Suppl. material 3.

Niphargus leopoliensis molnari: Schellenberg 1933, samples from the Abaligeti Cave, morphological data.

Niphargus molnari : Schellenberg 1935, morphological data.

Niphargus leopoliensis molnari, Niphargus molnari : Gebhardt 1933, 1934, 1963, 1967 distributional data

Niphargus molnari : Méhely 1941 additional morphological data.

Niphargus molnari : Angyal and Balázs 2013 morphological and distributional data.

Material examined for redescription.

7 females and 3 males from the stream of the Western 2. collateral of the Abaligeti Cave (Cadastre number: 4120-1, Hungarian Cave Cadastre), collected in 23 March 2013 (leg. D. Angyal and A. Illés), dissected and mounted on slides; additional 4 specimens not dissected. Slides were deposited in the Collection of Crustaceans of the Hungarian Natural History Museum with the following codes: N.MOL-02, N.MOL-03, N.MOL-04, N.MOL-06, N.MOL-07, N.MOL-08, N.MOL-09, N.MOL-10, N.MOL-11, N.MOL-12. Diagnostic voucher number of specimen used for molecular studies: NB555 ( Niphargus molnari , coll. data: Abaligeti Cave, Western 2. collateral, stream, 23 March 2013, leg. D. Angyal & A. Illés).

COI Gen Bank Accession Number: KP967552

Diagnosis.

Small to medium-sized niphargid; epimeral plate III postero-ventral corner sharply inclined. Telson with 3-4 apical spines, 1-3 lateral spines, 0-2 lateral plumose setae, 0-2 spines in cleft, dorsal surface with 1-3 spines in mediobasal position. Maxilla I outer lobe with 7 spines, 1.-3. pluri-toothed, 4.-7. variable (uni-, bi-, pluri-toothed). Gnathopod I and gnathopod II dactyli with single seta on outer margin. Gills II-VI ovoid, approximately same size as pereopod VI coxa, posterior margin slightly concave. Pleopods I-III with 2 retinacles on each. Uropod I lenght of endopodite: length of exopodite ratio as 1.00: (1.00-1.20) on males and 1.00: (1.15-1.18) on females. Uropod III sexually dimorphic, exopodite rod-shaped, distal article of exopodite on males 83-115% of proximal article length and 18-73% on females.

Description.

Body and telson. Small to medium-sized species, females are 6.4 mm to 9.0 mm, males are 7.8 mm to 10.6 mm. Head length up to 13% of body length; rostrum absent. Pereonites I–VI without setae; pereonite V, VI, VII with 1 postero-ventral seta each. Pleonites I–III with 3-6 setae along dorso-posterior margin (Fig. 3). Epimeral plate II ventral and posterior margins straight or sinusoid, ventro-postero-distal corner approximately perpendicular and pointed; along ventral margin 1-3 spiniform setae; along posterior margin 4-6 thin setae (Figs 3, 4). Epimeral plate III ventral margin convex and posterior margin straight, ventropostero-distal corner sharply inclined, strongly produced; along ventral margin 2-3 spiniform setae; along posterior margin 4-6 thin setae (Figs 3, 4). Urosomite I postero-dorso-laterally with 1-2 spiniform seta; urosomite II postero-dorso-laterally with 2-3 spiniform setae; urosomite III without setae. Near insertion of uropod I 1 spiniform seta (Fig. 3).

Telson length: width as 1.0: 0.6-0.8; cleft 71-87% of length; lobes apically rounded. Telson spines (per lobe): 3-4 apical spines; lateral margins with 1-3 spine, 0-2 plumose setae; 0-2 in cleft spines, dorsal surface with 1-3 basal spines in mediobasal position (Figs 4, 9). Length of apical spines 20-25% of telson length.

Antennae and mouthparts. Antenna I 35-48% of body length. Flagellum with up to 19 articles; each article with 1 long aesthetasc. Peduncle article 1: 2: 3 proportions 1.0: 0,78 (0.72-0.88): 0,4 (0.36-0.46). Proximal article of peduncle dorso-distally slightly produced. Accessory flagellum biarticulated; distal article shorter than one-half of the proximal article. Lengths of antennae I: II as 1.0: 0.50. Flagellum of antenna II with 6-8 articles. Lengths of peduncle articles 4: 5 as 1.0: (0.84-0.95); flagellum 54-70% of peduncle length (articles 4 + 5) (Fig. 5).

Inner lobes of labium longer than half of outer lobes (Fig. 5).

Left mandible: incisor with 5 teeth, lacinia mobilis with 4 teeth; between lacinia and molar 6-9 thick, serrated setae, long seta at base of molar absent (Fig. 5).

Right mandible: incisor processus with 4-5 teeth, lacinia mobilis with several small denticles (more then 12), between lacinia and molar 6-7 thick, serrated setae, long seta at base of molar present. Proportions of mandibular palp articles 2: 3 (distal) as 1.0: 1,20 (1.17-1.32). Proximal palp article without setae; second article with 9-11 seta in 5-6 groups; distal article with 1 group of 3-5 'A setae’; 3 groups of 'B setae’; 16-24 'D setae’; 3-5 'E setae’ (Fig. 5).

Maxilla I distal palp article with 2-3 apical and subapical setae. Outer lobe of maxilla I with 7 spines, 1-3 spines are always pluri-toothed with 3-6 lateral tooth while 4-6 spines are uni-, or bitoothed. Inner lobe with 1-2 setae (Fig. 5).

Maxilla II inner lobe slightly smaller than outer lobe; both of them setose apically and subapically, number of setae is approximately 13-23 per lobe (Fig. 5).

Maxilliped palp article 2 with 11-17 rows of setae along inner margin; distal article with dorsal seta and group of small setae at base of nail. Maxilliped outer lobe with 6-12 flattened, thick setae and 3-8 serrated setae; inner lobe with 2-3 flattened, thick setae apically and 5-9 serrated setae (Fig. 5).

Coxal plates. Coxal plate I width: depth as 1.00: 1.03 (0.89-1.16), of flattened rhomboid shape, antero-ventral corner subrounded; anterior and ventral margin of coxa I with 3-6 setae (Fig. 6). Coxal plate II width: depth as 1.00: 0.84 (0.76-0.95); anterior and ventral margin with 5-8 setae. Coxal plate III width: depth as 1.00: 0.82 (0.71-1.00); along antero-ventral margin 4-7 setae (Fig. 7). Coxal plate IV width: depth as 1.00: 1.03 (1.26-0.88); posteriorly concave; along antero-ventral margin 5-7 setae (Fig. 7). Coxal plates V-VI: anterior lobe well developed; along posterior margin 1 seta (Fig. 7). Coxal plate VII half-egg shaped, along posterior margin 1 seta (Fig. 7). Gills II-VI ovoid, with approximately same size as coxa VI (Fig. 7).

Gnathopods. Basis width is 38 (33-45)% of basis length. Gnathopod I ischium with 4-8 posterodistal setae in 1 row. Carpus length 62 (57-75)% of basis length and 87 (80-100)% of propodus length. Anterior margin of carpus only with distal group of setae; carpus posteriorly with transverse rows of setae proximally and a row of lateral setae, posterior enlargment small. Propodus subquadrate, palm convex. Along posterior margin 6-8 rows of denticulated setae. Anterior margin with 10-17 setae in 2-3 groups, antero-distal group with 6-12 setae. Group of 2-4 facial setae below (proximal of) palmar spine; 2-4 single surface setae present. Palmar corner with palmar spine, single supporting spine on inner surface, and 3 (rarely 4) denticulated, thick spiniform setae on outer side. Nail length 36 (34-37)% of total dactylus length; along anterior margin single seta; along inner margin 4-5 setae (Fig. 6).

Gnathopod II basis width: length as 1.0: 0.26 (0.21-0.29). Ischium with 2-6 postero-distal setae. Carpus length 56 (50-61)% of basis length and 86 (71-94)% of propodus lenght. Anterior margin of carpus only with distal row of setae; carpus posteriorly with transverse rows of setae proximally, a row of lateral setae; postero-proximal bulge small, positioned proximally. Propodus medium-sized (sum of length, diagonal and palm length measures up to 19 (15-21)% of body length) and larger than propodus of gnathopod I (1.0: 0.57 (0.65-0.85)). Propodus rectangular, palm convex. Posterior margin convex with 6-9 rows of denticulated setae. Anterior margin with 10-20 setae in 3-5 groups; antero-distal group with 7-9 setae. 1 group of 2-3 facial setae below (distal of) palmar spine; 1-4 individual surface setae present. Palmar corner with strong palmar spine, single supporting spine on inner surface, and 1 denticulated, thick spiniform seta on outer side. Nail length 31 (22-36)% of total dactylus length. Along anterior margin single seta; along inner margin 4-6 short setae (Figs 4, 6).

Pereopods III-IV. Proportions of pereopods III: IV as 1: 0.95 (0.93-0.97). Dactylus IV 45 (39-51)% of propodus IV; nail length 47 (39-52)% of total dactylus length. Dactyli III–IV with one dorsal plumose seta, one spine-like seta at the base of the nail, and tiny seta near the spine-like seta (sometimes not visible or absent). Additional spiniform setae on posterior margin are absent (Fig. 7).

Pereopods V-VII. Proportions of pereopods V: VI: VII as 1.00: 1.4 (1.37-1.54): 1.5 (1.42-1.61). Pereopod VII length 47 (42-52)% of body length. Basis V-VII narrow with convex posterior margins. Basis V width is 70 (60-78)% of length, basis VI is 67 (59-76)% of length and basis VII is 66 (56-76)% of length. Basis V with small posterodistal lobe, posterior margin with 8-13 setae, anterior margin with 6 -8 groups of setae. Dactylus V with one dorsal plumose seta, one spine-like seta at the base of the nail, and tiny seta near the spine-like seta (sometimes not visible or absent). Additional spiniform setae on posterior margin are absent (Fig. 7). Basis VI with small posteriodistal lobe, posterior margin with 9-14 setae, anterior margin with 6-10 setae. Dactylus VI with one dorsal plumose seta (sometimes not visible or absent), one spine-like seta at the base of the nail, and tiny seta near the spine-like seta (sometimes not visible or absent). Additional spiniform setae on posterior margin are absent (Fig. 8).

Basis VII posterior margin with 6-13 setae, anterior margin with 6-11 groups of setae. Total number of basis setae is 15-21. Dactylus VII length 26 (24-29)% of propodus VII length; nail length 26 (16-33)% of total dactylus length. Dactylus VII with one spine-like seta at the base of the nail. Additional spiniform setae on posterior margin are absent (Fig. 8).

Pleopods. Pleopods I-III with 2-hooked retinacles. Pleopod II rami of 16-20 articles each (Figs 4, 8).

Uropods. Uropod I basipodite with 6 dorso-lateral and 6 dorsomedial spinifom setae. Length ratio endopodite: exopodite as 1.00: 0.89 (0.83-1.0); rami slightly curved. Endopodite total setae number 2-4 in 2-3 groups, apically 5 spinifom setae. Exopodite with 2-7 spines; apically 5 spinifom setae (Fig. 9).

Uropod II endopodite: exopodite length as 1.00: 0.81 (0.77-0.9) (Fig. 9).

Uropod III up to 38-46% (males) and 12-42% (females) of body length. Basipodite with no lateral seta and 3-6 apical spiniform and thin setae. Endopodite 58-61% (males) and 48-70% (females) of basipodite length, endopodite apically with 1-2 thin-flexible and spiniform setae; laterally 0-1 seta. Exopodite of uropod III rod-shaped, distal article of exopodite 83-115% (males) and 18-73% (females) of proximal exopodite article length. Proximal article with 4-5 groups of plumose, thin-flexible and spiniform setae along inner margin and 4 groups of thin-flexible and spiniform setae along outer margin. Distal article with 3-6 apical setae; lateral setae only in males (Fig. 9).