Niphargus fiseri sp. nov.

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Figs 1, 7–10

Diagnosis (based on male only)

Antenna I is shorter than half of the total body length. The palpus of maxilla I is as long as the outer lobe. The palmar corner of gnathopods I–II has two short supporting spines. Gnathopods I–II bear trapezoidal shape of propodi. Gnathopods I–II dactyli have a single seta on the outer margin. Pereopod VI is longer than pereopod VII. Urosomite I bears one simple seta and urosomite II bears two spines on dorso-lateral margin. The outer ramus in uropod I is shorter than the inner ramus. Epimeral plates I–II are partly pointed. The lobes of the telson bear three distal and one marginal spines. The telson cleft is more than half of the telson length.

Etymology

The species is named in honor of Dr. Cene Fišer, University of Ljubljana, Slovenia who dedicated his research to the examination and exploration of subterranean amphipod diversity.

Material examined

Holotype

IRAN • ♂; West Azerbaijan Province, Piranshahr City, Badin Abad Spring; 36°34′55″ N, 45°10′34″ E; 24 Aug. 2016; M. Mamaghani-Shishvan leg.; ZCRU Amph. 1073.

Paratypes

IRAN • 2 ♀♀ (body length between 6.8 and 7.5 mm); same data as for holotype; ZCRU Amph.1073 .

Description of holotype

MEASUREMENTS. Total male body length is 8 mm. Head reperesents 18% of total body length (Fig. 7C). Antenna I is 0.39 times body length. Peduncular articles 1–3 progressively shorter; length of peduncular articles 3 exceeds half of peduncular article 2 (ratio 1.21:1); main flagellum with 16 articles (most with short setae), articles with up to one aesthetasc. Accessory flagellum bi-articulated and reaching ½ of article 4 of main flagellum, with one and two setae, respectively (Fig. 7A).

ANTENNAE. Antenna II with flagellum formed of seven articles, approximately half as long as antenna I. Flagellum length is 0.90 of length of peduncle article 4+ 5. Peduncular article 4 slightly longer than article 5, with seven and five groups of setae, respectively (Fig. 7B).

MOUTH PARTS. Labium (Fig. 8D) bi-lobate; with setae on the tip of lobes. Inner plate of maxilla I with two long apical setae; outer plate with seven spines with 3-2-2-1-0-1-0 lateral projections; palp bi-articulated, as long as outer lobe, with three long apical setae (Fig. 7 D–E). Both plates of maxilla II with numerous distal setae and two lateral setae (Fig. 8E). Left mandible with five teeth on incisor process, lacinia mobilis with four teeth and a row of seven setae with lateral projections (Fig. 7F). Right mandible with four teeth on incisor process, lacinia mobilis pluritoothed and row of five setae with lateral projections (Fig. 7G). Mandibular palp articles 1: 2:3 represent 22%, 35% and 43% of total palp length. Proximal article without setae, second article with five setae along inner margin and third article with one group of two A-setae, two groups of B-setae, no C-setae, 17 D-setae and five E-setae (Fig. 7H). Maxilliped with normal inner plate on which four distal spines intermixed with five distal and one simple long lateral setae subdistally; outer plate exceeding half of posterior margin of palp article 2, with nine spines along inner margin and three simple setae distally. Maxilliped palp article 3 with one proximal, inner and outer group of long simple setae at outer margin; palp terminal article with one simple seta at outer margin, nail shorter than pedestal (Fig. 8C).

GNATHOPODS. Gnathopod II larger than gnathopod I. Coxal plate of gnathopod I rounded, broader than long. Coxa I ventral margin with four setae. Basis with setae on anterior and posterior margins; ischium and merus with posterior group of setae. Carpus with one group of three setae antero-distally, bulge with long setae; carpus 0.53 times basis length and 0.88 times propodus length. Propodus longer than broad; anterior margin with three setae in one group in addition to antero-distal group of five setae. Palm slightly convex, defined on outer surface by one strong long corner S-seta accompanied laterally by one L-seta with lateral projections and row of three facial M-setae and by two short sub-corner R-setae on inner surface. Dactylus reaching posterior margin of propodus, outer and inner margins with row of one and two setae, respectively; nail short, 0.45 times total dactylus length (Fig. 8A). Coxal plate of gnathopod II slightly rounded, with five setae along antero-ventro-posterior margins. Basis with setae along anterior and posterior margins; posterior margins of ischium and merus with one posterior group of setae each. Carpus 0.64 times basis length and 0.90 times propodus length. Carpus with one group of two setae antero-distally. Propodus in gnathopod II larger than gnathopod I, rectangular and longer than broad; anterior margin with two setae in one group in addition to antero-distal group of four setae. Palm convex, defined on outer surface by one strong long corner S-seta accompanied laterally by one L-seta with lateral projections and row of three facial M-setae, on inner surface by two short sub-corner R-setae. Dactylus reaching posterior margin of propodus, outer and inner margins of dactylus with one and three setae, respectively. Nail length 0.45 of total dactylus length (Fig. 8B). Coxal plate III with rectangular shape, length to width ratio is 1.42: 1; antero-ventral margin with five setae. Coxal plate IV with rectangular shape, ventral margin with four setae, posterior concavity shallow and approximately 0.1 of coxa width (Fig. 9 A–B). Coxal plates V–VI with two and one setae on anterior and posterior lobes, respectively. Coxal plate VII with one seta (Fig. 9 C–E).

PEREOPODS. Pereopod III: IV length ratio1.03: 1 (Fig. 9 A–B).Dactylus IV short, dactylus length 0.43 times propodus length, nail shorter than pedestal (Fig. 9B). Pereopods V:VI: VII length ratios 1: 1.27: 1.15, respectively. Pereopod VII 0.45 times body length. Pereopod bases V and VII each with five groups of spines along anterior margins and with eight setae along posterior margins, respectively (Fig. 9C, E). Pereopod base VI with six groups of spines along posterior margin and with eight setae along anterior margin (Fig. 9D). Postero-ventral lobe of ischium in pereopods V–VII developed. Ischium, merus and carpus in pereopods V–VII with several groups of spines and setae along anterior and posterior margins; propodus of pereopod VII longer than these in V–VI, dactyli of pereopods V–VII with one spine and one short seta at base of nail on inner margin, nail length of pereopod VII 0.50 times of total dactylus length (Fig. 9 C–E).

EPIMERAL PLATES I–III (Fig. 10G). With angular postero-ventral corner, anterior and ventral margins convex; postero-ventral corners of plates I–III posteriorly with two, two and three spines and setae, respectively. Epimeral plates II–III each with two spines along of ventral margins. Peduncle of pleopods I–III with two-hooked retinacles at distal part of inner margins. Peduncle of pleopods II–III with one and two setae along of inner margin (Fig. 10 A–C); rami of pleopods I–III each with five to nine articles (Fig. 10 A–C).

PEREONITES. Pereonites I–VII without setae. Pleonites I–III each with one seta in middle of article on dorsal margin. Urosomites I–II with one seta and two spines dorso-laterally, respectively. Urosomite III without setae. Urosomite I with one spine at base of uropod I.

UROPODS. Peduncle of uropod I with four and three large spines along dorso-lateral and dorso-medial margins, respectively. Inner ramus of uropod I longer than outer ramus (ratio 1: 1.04); inner ramus with two groups of three spines laterally and five spines distally; outer ramus with two groups of three spines laterally and five spines distally (Fig. 10D). Inner ramus in uropod II longer than outer, both rami with lateral and distal long spines (Fig. 10E). Uropod III normal, almost 0.40 times body length. Peduncle of uropod III with five spines, outer ramus bi-articulated, distal 0.17 proximal articles. The proximal article of outer ramus bearing five and four groups of spines along inner and outer margins, respectively (Fig. 10F); distal article with four setae distally. Inner ramus short, with one distal spine and one lateral seta. Telson two times as long as broad, lobes slightly narrowing; each lobe with three spines distally, with one long spine and two plumose setae laterally (Fig. 10H).

Female

Unknown.

Remarks

Niphargus fiseri sp. nov. is diagnozed mainly by two characters. The first one is the presence of two supporting spines (R-setae sensu Karaman 2018) in both gnathopods, so far observed only in one species from Europe ( N. kenki Karaman, 1952), but it seems to be more common in Iran. This character has been reported in N. bisitunicus Esmaeili-Rineh, Sari & Fišer, 2015 and N. lorestanensis Esmaeili-Rineh, 2018 . However, in the latter two species, the propodi in gnathopod I are more rectangular and more elongated. The second character is the length of the nail to pedestal ratio in the dactyli of gnathopods I to II that includes more than ½ of the dactyli in N. fiseri sp. nov. So far, this character has not been described in Iranian species.