Niphargus gebhardti Schellenberg, 1934

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 : 65-71

Taxon classification Animalia Amphipoda Niphargidae

Niphargus gebhardti Schellenberg, 1934

Niphargus foreli gebhardti n. subsp.: Schellenberg 1934; Type locality: Abaligeti Cave. Data from the original description is available in Suppl. material 3.

Niphargus foreli gebhardti: Schellenberg 1935, additional morphological data

Niphargus foreli gebhardti, Niphargus gebhardti : Gebhardt 1934, 1963, 1967, distributional data

Niphargus gebhardti : Méhely 1941, morphological data

Niphargus foreli gebhardti: Dudich 1941, distributional data

Niphargus gebhardti : Angyal and Balázs 2013, morphological and distributional data

Material examined for redescription.

7 females and 4 males from a permanent pool in the main passage near 'Karthago romjai’ hall of the Abaligeti Cave (Cadastre number: 4120-1, Hungarian Cave Cadastre), collected on 23 March 2013 (leg. D. Angyal & 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.GEB-02, N.GEB-03, N.GEB-04, N.GEB-05, N.GEB-08, N.GEB-10, N.GEB-14, N.GEB-15, N.GEB-17, N:GEB-18, N.GEB-20. Diagnostic voucher numbers of specimens used for molecular studies: NB 550 ( Niphargus gebgardti , coll. data: Abaligeti Cave, main passage, pool, 23 March 2013, leg. D. Angyal & A. Illés), NB 551 ( Niphargus gebgardti , coll. data: Szajha-felső Sinkhole (Cadastre number: 4120-16), small pool, 2 April 2013, leg. D. Angyal & Z. Tegzes).

COI Gen Bank Accession Numbers: KP967553 (Abaligeti Cave), KP967554 ( Szajha-felső Sinkhole)

Diagnosis.

Small-sized niphargid; epimeral plate III postero-ventral corner subrounded. Telson with 3-6 apical spines, 0-2 lateral spines, 0-1 lateral plumose setae, 0-1 spines in cleft and 0-1 dorsal surface spines. Maxilla I outer lobe with 7 spines, pluri-, uni-, bi-toothed spines alternating. Gnathopod I and gnathopod II dactyli with single seta on outer margin. Gills II-VI ovoid. Pleopods I-III with 3, rarely 4 retinacles on each. Uropod I lenght of endopodite: length of exopodite ratio as 1.00: (1.09-1.11) on males and 1.00: (1.03-1.17) on females. Uropod II sexually dimorphic, exopodite rod-shaped, distal article of exopodite on males 95-155% of proximal article length and 52-72% on females.

Description.

Body and telson. Small-sized niphargid species, females 4.9-5.9 mm, males 5.9-7.0 mm. Head length up to 9% of body length; rostrum absent. Pereonites I-VI without setae; pereonite V, VI, VII with 1 postero-ventral seta each. Pleonites I-III with 1-2 setae along dorso-posterior margin. Epimeral plate II posterior and ventral margins convex, ventro-postero-distal corner rounded. Along ventral margin 1-3 spiniform setae; along posterior margin 3-4 thin setae. Epimeral plate III ventral and posterior margins convex, ventro-postero-distal corner rounded; along ventral margin 2-3 spiniform setae; along posterior margin 4 thin setae. Urosomite I postero-dorso-laterally with 1 seta; urosomite II postero-dorso-laterally with 1 spiniform seta; urosomite III without setae. Near insertion of uropod I 1 spiniform seta (Figs 10, 11).

Telson length: width as 1.0: 0.88; cleft 74 (70-79)% of length; lobes apically widely rounded. Telson spines (per lobe): 2-4 apical spines, 33.5 (28-39)% of telson length; lateral margins with 0-2 spine and 0-1 plumose setae; 0-1 in cleft spines, 0 or 1 dorsal surface spines, 1 basal spine (Figs 11, 16).

Antennae and mouthparts. Antenna I 37 (34-41)% of body length. Flagellum with up to 13-16 articles; each article with 1 long aesthetasc (Fig. 11). Peduncle article 1: 2: 3 as 1.0: 0.69 (0.60-0.76): 0.37 (0.30-0.4). Proximal article of peduncle dorso-distally slightly produced. Accessory flagellum biarticulated; distal article 52 (38-67)% of proximal article. Lengths of antennae I: II as 1.0: 0.48 (0.42-0.52). Flagellum of antenna II with 6-8 articles. Lengths of peduncle articles 4: 5 as 1.0: 0.85 (0.81-0.91); flagellum 73 (57-81)% of peduncle length (articles 4+5) (Fig. 12).

Inner lobes of labium longer than half of outer lobes (Fig. 12).

Left mandible: incisor with 5 teeth, lacinia mobilis with 4 teeth; between lacinia and molar 5-7 thick, serrated setae, long seta at base of molar absent (Fig. 12).

Right mandible: incisor processus with 4 teeth, lacinia mobilis with 5-6 denticles, between lacinia and molar 6-8 thick, serrated setae, 1 long seta at base of molar present. Proportions of mandibular palp articles 2: 3 (middle: distal) as 1.0: 1.1 (1.00-1.21). Proximal palp article without setae; second article with 4-6 seta in 3-4 groups; distal article with 1 group of 3-4 'A setae’; 2-4 of 'B setae’ (single or in groups); 9-13 'D setae’ and 3-5 'E setae’ (Fig. 12).

Maxilla I distal palp article with 3-6 apical and subapical setae. Outer lobe of maxilla I with 7 spines, pluri-, uni-, bi-toothed spines alternating. Inner lobe with 1 seta (Fig. 12).

Maxilla II inner lobe slightly smaller than outer lobe; both of them setose apically and subapically, number of setae is approximately 6-11 on inner lobe and 8-12 on outer lobe (Fig. 12).

Maxilliped palp article 2 with 8-11 rows of setae along inner margin; distal article with dorsal seta and group of small setae at base of nail. Maxilliped outer lobe with 6-8 flattened, thick setae and 3-5 serrated setae; inner lobe with 2-3 flattened, thick setae apically and 2-4 serrated setae (Fig. 12).

Coxal plates. Coxal plate I width: depth as 1.00: 0.76 (0.6-0.9) of flattened rhomboid shape, antero-ventral corner subrounded; anterior and ventral margin of coxa I with 4-6 setae (Fig. 13). Coxal plate II width: depth as 1.00: 0.97 (0.83-1.21); anterior and ventral margin with 3-6 setae (Fig. 13). Coxal plate III width: depth as 1.00: 1.12 (1.05-1.2); along antero-ventral margin 4-6 setae. Coxal plate IV width: depth as 1.00: 1.04 (0.97-1.12); posteriorly concave; along antero-ventral margin 4-5 setae (Fig. 14). Coxal plates V-VI with well developed anterior lobe, and smaller posterior lobe with usually 2 setae (occasionally with 1 or 3) in postero-ventral corner. Coxal plate VII half-egg shaped, along posterior margin 2 setae. Gills II-VI ovoid, of approximately similar size as coxa VI (Fig. 15).

Gnathopods. Gnathopod I basis width 42 (38-47)% of basis length. Ischium with 3-4 posterodistal setae in 1 row. Carpus length 61 (52-82)% of basis length and 98 (87-110)% 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 and posterior margin convex. Along posterior margin 3-4 rows of denticulated setae. Anterior margin with 6-11 setae in 2-3 groups, antero-distal group with 4-8 setae. Group of 2-3 facial setae below (proximal of) palmar spine; 1-4 surface setae in 1-2 groups present. Palmar corner with palmar spine, single supporting spine on inner surface, and 2-3 denticulated, thick spiniform setae on outer side. Nail length 33 (30-39)% of total dactylus length; along anterior margin single seta; along inner margin 3-4 setae (Fig. 13).

Gnathopod II basis width: length as 1.0: 0.34 (0.27-0.45). Ischium with 3-4 postero-distal setae in 1 row. Carpus length 59 (48-69)% of basis length and 106 (96-111)% of propodus length. 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 and positioned proximally. Propodus small to medium-sized (sum of length, diagonal and palm length measures up to 12-15% of body length) and larger than propodus of gnathopod I (1.0: 0.87 (0.78-0.96)). Propodus rectangular, palm convex. Posterior margin straight or convex with 4-5 rows of denticulated setae. Anterior margin with 3-9 setae in 1-2 groups; antero-distal group with 4-8 setae. Group of 2-4 facial setae below (proximal of) palmar spine; 2-3 surface setae in 1-2 groups present. Palmar corner with strong palmar spine, single supporting spine on inner surface, and 2-3 denticulated, thick spiniform setae on outer side. Nail length 34 (29-42)% of total dactylus length. Along anterior margin single seta; along inner margin 3 short setae (Fig. 13).

Pereopods III–IV. Proportions of pereopods III: IV as 1: 0.96 (0.89-1). Dactylus IV 51 (46-57)% of propodus IV lenght; nail length 53 (44-61)% of total dactylus length. Dactyli III-IV with 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. 14).

Pereopods V–VII. Proportions of pereopods V: VI: VII as 1.00: 1.3 (1.27-1.49): 1.5 (1.46-1.58). Pereopod VII length 42-45% of body length. Basis V-VII with convex posterior margins. Basis V width is 71 (66-80)% of length, basis VI is 68 (64-73)% of length, and basis VII is 66 (63-69)% of length. Basis V with small posterodistal lobe, posterior margin with 4-6 setae, anterior margin with 4-9 setae in 3+1 groups (Fig. 14). Pereopod dactylus V with one dorsal plumose seta (sometimes not visible or absent), and one spine-like seta at the base of the nail (Fig. 14). Basis VI with small posterodistal lobe, posterior margin with 6-7 setae, anterior margin with 5-8 setae in 3-4 groups. Dactylus VI with 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. 15). Basis VII posterior margin with 5-8 setae, anterior margin with 3-5 groups of setae. Total number of basis setae is 11-15. Dactylus VII length 26 (23-35)% of propodus VII length; nail length 28.5 (25-38)% of total dactylus length. Dactyli 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. 15).

Pleopods. Pleopods I-III with 3, rarely 4 hooked retinacles. Pleopod II rami of 11-13 articles each (Figs 11, 15).

Uropods. Uropod I basipododite with 4-5 dorso-lateral and 1-3 dorsomedial spiniform setae including spiniform setae in distal position. Length ratio endopodite: exopodite as 1.00: 0.91 (0.87-0.97); rami slightly curved. Endopodite with 1-2 setae, apically 5 spinifom setae. Exopodite with 1-4 setae or spines in 1-2 groups; apically 5 spinifom setae (Figs 11, 16).

Uropod II endopodite: exopodite length as 1.00: 0.84 (0.77-0.95) (Figs 11, 16).

Uropod III 38 (37-39)% (males) and 26 (24-30)% (females) of body length. Basipodite with 0-1 lateral setae and 5-6 apical spiniform and thin setae. Endopodite 41 (39-44)% (males) and 48 (41-54)% (females) of basipodite length; endopodite apically with 0-2 thin-flexible and spiniform setae; laterally with 0-1 seta. Exopodite of uropod III rod-shaped, distal article of exopodite 100 (95-105)% (males) or 60 (52-78)% (females) of proximal article length. Proximal article with 3-4 groups of plumose, thin-flexible and spiniform setae along inner margin and 2-4 groups of thin-flexible and spiniform setae along outer margin. Distal article without lateral seta (males) or with 3 setae in 1 group (females); apically 4-7 setae (Figs 11, 16).