Niphargus sahandensis, Mamaghani-Shishvan & Akmali & Fišer & Esmaeili-Rineh, 2024

Order Amphipoda Latreille, 1816 Suborder Senticaudata Lowry and Myers, 2013 Family Niphargidae Bousfield, 1977 Genus Niphargus Schiödte, 1849

Niphargus sahandensis sp. nov. ( Figs. 3–6 View Fig View Fig View Fig View Fig ) urn:lsid:zoobank.org:act:B233ED2D-3CC8-47C6-AFD0-B88950D19464

Type locality and Material examined: Holotype, Male specimen (7 mm) from Hargalan Spring, Ajabshir City, East Azerbaijan Province, Iran, coordinates (N 37°37'35", E46°09'50"). Specimens collected by M. Mamaghani-Shishvan; 11 Aug 2022 GoogleMaps . Holotype with two paratypes are stored under catalogue number ZCRU Amph.1604 .

Etymology: The name “sahandensis ” refers to Sahand Mountain in East Azerbaijan ( Iran). Hargalan Spring is located on its slope.

Diagnosis: Peduncle of pleopods I to III with 3–4 hooked retinacles at distal part of inner margin. At the base of uropod I peduncle with two spines. Maxilla I palp long, reaching beyond the tip of the outer lobe. A relatively equal size of coxae of gnathopods I–II. The propodi of gnathopod I with two supporting spines in palmar corner. Ventro-posterial corner in epimeral plates I to III not produced. Rectangular shape of propodi in both gnathopods. Outer ramus of uropod I slightly shorter than inner ramus.

Description of holotype: Measurements: The total length of the holotype is 7 mm. Head represents 12% of the total body length ( Fig. 3A View Fig ).

Antennae: Antenna I is 0.40 times body length. Peduncular articles 1–3 progressively shorter; length of peduncular article 3 exceeds half of peduncular article 2 (ratio 1.00: 1.32). Main flagellum with 14 articles (most with short setae). Accessory flagellum bi-articulated and reaching 0.5 of article 4 of main flagellum; both articles with two and three setae, respectively ( Fig. 3B View Fig ). Antenna II with flagellum formed of 9 articles, approximately 0.80 times as long as antenna I. Flagellum length is 0.84 times the length of peduncle articles 4 + 5. Peduncular article 4 of antenna II is longer than article 5 (1.12: 1.00), peduncle articles 4 and 5 with seven and eight groups of setae, respectively ( Fig. 3C View Fig ).

Mouth parts: Labium ( Fig. 4D View Fig ) bi-lobate; with fine setae on tip of outer lobes. Inner plate of maxilla I with one long apical seta, outer plate with seven long spines with 3-1-1-2-1-1-1 lateral projections; palp bi-articulated, long and reach the tip of outer lobe, with three apical setae ( Fig. 3E–F View Fig ). Both plates of maxilla II with numerous long distal setae ( Fig. 4E View Fig ). Mandibles: left mandible with five teeth on incisor process, lacinia mobilis with four teeth, between lacinia and molar a row of seven setae with lateral projections ( Fig. 3F View Fig ). Right mandible with four teeth on incisor process, lacinia mobilis pluritooth, between lacinia and molar a row of five setae with lateral projections ( Fig. 3G View Fig ). Mandibular palp articles 1:2:3 represent 21%, 38% and 41% of total palp length, respectively. Proximal article without setae; second article with five setae along inner margin and third article with one group of one A-seta, two groups of B-setae, no C-setae, 12 D-setae and five E-setae ( Fig. 3D View Fig ). Maxilliped with short inner plate bearing four distal spines intermixed with six distal setae; outer plate less than half of palp article 2, with 9 spines along inner margin and 4 setae distally; maxilliped palp article 3 at outer margin with one proximal and one distal group of long setae; palp terminal article with one seta at outer margin and two setae at base of nail, nail shorter than pedestal ( Fig. 4C View Fig ).

Gnathopods: Coxal plates of gnathopods I–II almost equal in size. Coxa of gnathopod I trapezoid, antero-ventral margins with four marginal setae. Basis with setae on anterior and posterior margins; ischium and merus with posterior group of setae. Carpus with one group of four setae antero-distally, bulge with long setae; carpus 0.61 times basis length and 0.65 times propodus length. Propodus of gnathopod I rectangular in shape and longer than broad; anterior margin with four 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 two L-setae with lateral projections, on inner surface by two short sub-corner R-setae. Dactylus reaches posterior margin of propodus, outer and inner margins of dactylus with one and three simple setae, respectively. Nail length 0.25 times total dactylus length ( Fig. 4A View Fig ).

Coxal plate of gnathopod II with square, ventral margins with four setae. Basis with setae on anterior and posterior margins; ischium and merus with posterior group of setae. Carpus with one group of two setae antero-distally, bulge with long setae; carpus 0.61 times basis length and 0.85 times propodus length. Propodus longer than broad; anterior margin with two setae in one group in addition to antero-distal group of three setae. Palm slightly convex, defined on outer surface by one strong, long corner S-seta accompanied laterally by two L-setae with lateral projections, on inner surface by one short sub-corner R-seta. Dactylus reaching posterior margin of propodus, outer and inner margins of dactylus with one and four simple setae, respectively; nail short, 0.28 times total dactylus length ( Fig. 5B View Fig ).

Pereopods: Coxal plate III rectangular, length to width ratio is 1.13: 1; anterio-ventral margin with four setae. Coxal plate IV quadrate, anterio-ventral margin with four setae ( Fig. 5A–B View Fig ). Coxal plate V with posterior lobe, with two setae each on anterior and posterior lobes. Coxal plate VI with anterior lobe, with two simple setae on anterior lobe and one simple seta on posterior lobe. Coxal plate VII with one simple seta on posterior lobe ( Fig. 5E View Fig ).

Pereopod III: IV length ratio is 1.06: 1. Dactylus IV short, dactylus length 0.32 times propodus length, nail shorter than pedestal ( Fig. 5A–B View Fig ). Pereopods V: VI: VII length ratios 1: 1.37: 1.49, respectively. Pereopod VII is 0.61 times the total body length. Pereopod bases V and VII each with four groups of spines along the anterior margins and five and six groups of setae along the posterior margins, respectively. Pereopod basis VI with five groups of spines and seven groups of setae along the posterior and anterior margins, respectively ( Fig. 5C–E View Fig ). 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 the anterior and posterior margins, dactyli of pereopods V – VII with one spine at base of nail on inner margin and one short seta on outer margin in pereopods V – VI. Nail length of pereopod VII 0.40 times the total dactylus length ( Fig. 5C–E View Fig ).

Epimeral Plates: With angular postero-ventral corner, postero-ventral corners of plates I–III posteriorly with three, four and three setae and spines, respectively. Epimeral plates II–III each have two spines along the ventral margins ( Fig. 6H View Fig ).

Pleopoda: Peduncle of pleopods I have three hooked retinacles at distal part of inner margins; peduncles of pleopods II-III each have four hooked retinacles at distal part of inner margins. Peduncle of pleopod III with one seta along outer margin. Rami of pleopods I-III with five to nine articles ( Fig. 6A–C View Fig ).

Urosomites: Urosomites I–II with two and three setae on dorso-lateral margins, respectively. Urosomite III lacks setae. Urosomite I with two spines at base of uropod I.

Uropods: Peduncle of uropod I with seven and one large spines along dorso-lateral and dorso-medial margins, respectively. Outer ramus of uropod I slightly shorter than inner ramus (ratio 1: 1.02); inner ramus with two groups of two spines laterally and five spines distally; outer ramus with two groups of spines laterally and five spines distally ( Fig. 6D View Fig ). Inner ramus in uropod II longer than outer, both rami with lateral and distal long spines ( Fig. 6E View Fig ). Uropod III long, almost 0.31 times body length. Peduncle of uropod III with five spines, outer ramus bi-articulated, distal article 0.17 times proximal article. Proximal article of outer ramus bearing four and five groups of spines along outer and inner margins, respectively ( Fig. 6F View Fig ); distal article has lateral and distal setae. Inner ramus short, with one distal spine.

Telson: Longer than broad, lobes slightly narrowing; each lobe with three spines distally, with one plumose seta laterally ( Fig. 6G View Fig ).