Niphargus chaldoranensis, 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 chaldoranensis sp. nov. ( Figs. 7–10 View Fig View Fig View Fig View Fig ) urn:lsid:zoobank.org:act:6FC80139-410C-418D-B5C3-929A95A3F70C

Type locality and Material examined: Holotype,

Male specimen (8 mm) from Shoan Spring, Chaldoran City, West Azerbaijan Province, Iran, coordinates (N39°04'13", E44°09'28"). Specimens collected by M. Mamaghani-Shishvan; 6 Aug 2022. Holotype with three paratypes are stored under catalogue number ZCRU Amph.1602. GoogleMaps

Material examined: One male specimen (holotype) and two paratypes from Shoan Spring. Three male specimens were examined from Salmas Spring, close to Salmas City, West Azerbaijan Province, Iran, (38°12'48"N, 44°47'32"E); materials were collected by M. Mamaghani in 8 Aug 2022; Salmas materials are stored under catalogue number ZCRU Amph.1605.

Etymology: The name ‘ chaldoranensis ’ refers to the type locality (Chaldoran City) where the species was found.

Diagnosis: At the base of uropod I peduncle with only one spine. Trapezoid shape of propodi in both gnathopods. Maxilla I palp long, reaching beyond the tip of the outer lobe. Dactylus does not reach posterior margin of gnathopod I propodi. Pereopods V and VI with equal length. Pereopod VII propodi 1.5 times the pereopod VI propodi. Pereopod VII 60% of total body length.

Description of holotype: MEASUREMENTS. The total length of the holotype is 8 mm. Head represents 10% of the total body length ( Fig. 7C View Fig ).

Antennae: Antenna I ( Fig. 7B View Fig ) is 0.34 times body length. Peduncular articles 1–3 progressively shorter; length of peduncular article 3 exceeds half of peduncular article 2 (ratio 1.00: 1.58). Main flagellum with 12 articles (most with short setae). Accessory flagellum bi-articulated and 0.5 times the length of article 4 of main flagellum; both articles with two and one setae, respectively. Antenna II ( Fig. 7C View Fig ) with flagellum formed of 7 articles, approximately 0.63 times as long as antenna I. Flagellum length is 0.86 times length of peduncle articles 4+5. Peduncular article 5 of antenna II is longer than article 4 (1.13: 1.00), peduncle articles 4 and 5 each with five groups of setae.

Mouth parts: Labium ( Fig. 8C View Fig ) bi-lobate; with fine setae on tip of outer lobes. Inner plate of maxilla I with two apical setae, outer plate with seven long spines with 3-2-0-2-3-2-0 lateral projections; palp bi-articulated, long and reaching tip of outer lobe, with four apical setae ( Fig. 7D View Fig ). Both plates of maxilla II with numerous long distal and lateral setae ( Fig. 8D View Fig ). Mandible: Left mandible with five teeth on incisor process, between lacinia and molar a row of seven setae with lateral projections ( Fig. 7F View Fig ). Right mandible with five teeth on incisor process, between lacinia and molar a row of six setae with lateral projections ( Fig. 7G View Fig ). Mandibular palp articles 1:2:3 represent 24%, 36% and 39% of total palp length, respectively. 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, 9 D-setae and five E-setae ( Fig. 7E View Fig ). Maxilliped with short inner plate bearing three distal spines intermixed with seven distal setae; outer plate exceeds half of palp article 2, with 8 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 three setae at base of nail, nail shorter than pedestal ( Fig. 8E View Fig ).

Gnathopods: Coxal plates of gnathopod I slightly greater than those of gnathopod II. 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 two setae antero-distally, bulge with long setae; carpus 0.45 times basis length and 0.70 times propodus length. Propodus of gnathopod I trapezoidal in shape and longer than broad; anterior margin with four setae in one group in addition to an 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 one short sub-corner R-seta. Dactylus does not reach posterior margin of propodus, outer and inner margins of dactylus with two and three simple setae, respectively. Nail length 0.44 times total dactylus length ( Fig. 8A View Fig ).

Coxal plate of gnathopod II with trapezoid; anterior margins with five setae. Basis with setae on anterior and posterior margins; ischium and merus with posterior groups of setae. Carpus with one group of three setae antero-distally, bulge with long setae; carpus 0.63 times basis length and 0.77 times propodus length. Propodus longer than broad; anterior margin with two setae in one group in addition to an 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 reaches posterior margin of propodus, outer and inner margins of dactylus with two and four simple setae, respectively; nail long and 0.47 times total dactylus length ( Fig. 8B View Fig ).

Pereopods: Coxal plate III square, length to width equal; antero-ventral margin with four setae. Coxal plate IV rectangular, anterio-ventral margin with four setae ( Fig. 9A–B View Fig ). Coxal plate V with anterior lobe, with one and two setae on posterior and anterior lobes, respectively. Coxal plate VI with anterior lobe, with one simple seta on posterior lobe. Coxal plate VII with one simple seta on posterior lobe ( Fig. 9C–E View Fig ).

Pereopod III: IV length ratio is 1.04: 1 ( Fig. 9A–B View Fig ). Dactylus IV short, dactylus length 0.28 times propodus length, nail shorter than pedestal ( Fig. 9B View Fig ). Pereopods V: VI: VII length ratio 1: 1.007: 1.39. Pereopod VII is 60% total body length. Pereopod bases V – VII each with four groups of spines along anterior margins and six groups of setae along posterior margins, respectively ( Fig. 9C– 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 anterior and posterior margins, dactyli of pereopods V – VII with one spine seta at base of nail on inner margin, and one short seta on outer margin. Nail length of pereopod VII 0.33 times total dactylus length ( Fig. 9D– E View Fig ).

Epimeral Plates I–III ( Fig. 10H View Fig ). Angular postero-ventral corner, postero-ventral corners of plates I–III posteriorly with two, three and three setae and spines, respectively; ventral margin in plates II–III each with two spines.

Pleopods: Peduncles of pleopods I–III with two-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. 10A–B View Fig ).

Uropods: Urosomite I with one spine at base of uropod I. Peduncle of uropod I with seven and one large spines along dorso-lateral and dorso-medial margins, respectively. Outer ramus of uropod I shorter than inner ramus; inner ramus with one group of spines laterally and five spines distally; outer ramus with two groups of three spines laterally and five spines distally ( Fig. 10D View Fig ). Inner ramus in uropod II longer than outer, both rami with lateral and distal long spines ( Fig. 10E View Fig ). Uropod III long, almost 0.36 times body length. Peduncle of uropod III with four spines, outer ramus bi-articulated, distal article 0.76 times proximal article. Proximal article of outer ramus bear four and five groups of setae and spines along inner and outer margins, respectively ( Fig. 10F View Fig ); distal article with four setae distally. Inner ramus short, with one distal spine and one distal seta.

Telson: Longer than broad, lobes slightly narrowing; each lobe with three spines distally and two plumose setae laterally ( Fig. 10G View Fig ).

Interpopulational variation

Although differences between species, however small, can be important, differences between populations of the same species are also significant. A total of six individuals from the two populations of Shoan and Salmas were examined and compared. Many taxonomic traits seem to be stable; however, we observed some differences that may be taxonomically important. In particular, there are notable differences in the number of supporting spines in the palmar corner of gnathopod propodi II (between 1–2), the number of spines with lateral projections on the outer surface in the palmar corner of gnathopod propodi II (between 1–2), the shapes of gnathopod II propodi (rectangular to trapezoid), and the ratio of inner to outer ramus of uropod I (similar size to longer).