Niphargus sarii, Esmaeili-Rineh, Mohammad-Niakan & Akmali, 2018

Esmaeili-Rineh, Somayeh, Mohammad-Niakan, Ali & Akmali, Vahid, 2018, Niphargus Sarii Sp. N., A New Subterranean Niphargid (Crustacea: Amphipoda) From Iran Based On Molecular And Morphological Characters, Acta Zoologica Academiae Scientiarum Hungaricae 64 (2), pp. 113-132 : 118-124

Niphargus sarii sp. n.

( Figs 2–5)

URN:lsid:zoobank.org:pub: F0FCBA2D-3B44-46C0-9A71-2D529B13B26F

Holotype: male specimen (11.5 mm) from Jo-Khanem Spring , Chardavol City, Ilam Province, Iran; (33 ◦ 19’N, 46 ◦ 40’E). Specimens were collected by A.M. Niakan in May 2014 . Holotype with two paratypes is stored under catalogue number ZCRU Amph. 1001 in the Zoological Collection of Razi University , Iran ( ZCRU) .

Diagnosis – The rami in uropod I have equal length. The urosomites I to II bear dorso-laterally one and two robust setae accompanied with one simple seta, respectively. The propods of gnathopods I to II are broader than long. The dactylus of gnathopod II is not reaching to the posterior margin of propodus.

Description of holotype – Total length of specimen 11.5 mm. Body strong and stout. Head length 13% of body length ( Fig. 2). Antennae I ( Fig. 2) 0.47 of body length. Peduncular articles 1–3 progressively shorter; peduncular articles 2: 3 ratio 2: 1; main flagellum with 37 articles (most of which with short setae); accessory flagellum biarticulated and reaching 1/2 of article 4 of main flagellum, flagellar articles 1 and 2 with two and three simple setae, respectively ( Fig. 2). Length ratio of antenna I: II as 1: 0.45. Peduncular article 4 as long as article 5, with nine and eight groups of simple setae, respectively; flagellum with 13 articles. Length of flagellum: length of peduncle article 4 + 5 as 0.56: 1 ( Fig. 2).

Labium ( Fig. 3) with inner lobes and setae on tip of lobes. Inner plate of maxilla I with four long simple setae; outer plate with seven long robust setae with 1-0-2-0-2-5-0 apical lateral projections; palp biarticulated, longer than outer lobe, with three long distal simple setae ( Fig. 2). Both plates of maxilla II with numerous distal simple setae, with four lateral simple setae ( Fig. 3). Incisor in left mandible with five teeth, lacinia mobilis with four teeth; six setae with lateral projections between lacinia and triturative molar ( Fig. 2). Incisor in right mandible with four teeth, lacinia mobilis pluritooth; seven setae with lateral projections between lacinia and triturative molar ( Fig. 2). Mandibular palp articles ratios 1: 2: 3 as 1: 1.58: 2.41. The proximal article has no setae, the second article with 16 setae along inner margin and the third article with one group of four A-setae, two groups of B-setae, no C-setae, 25 D-setae and four E-setae ( Fig. 2).

Maxilliped with short inner plate on which are three distal robust setae intermixed with six distal simple setae; outer plate exceeding the proximal half of the posterior margin of palp article 2, with 12 robust setae along inner margin and four simple setae distally. Palp article 3 of maxilliped with one proximal, inner and outer group of long simple setae at outer margin; terminal article of palp with one simple seta at outer margin, nail shorter than pedestal ( Fig. 3).

Coxa of gnathopod I shorter than coxa of gnathopod II. Coxa I rectangular, longer than broad, ventral to anterior margin each with three simple setae. Basis with setae along anterior and posterior margins; ischium and merus with posterior group of setae. Carpus with one group of four setae anterodistally, a bulge with long simple setae; carpus 0.54 of basis length and 0.71 of propodus length. Propodus slightly broader than long; anterior margin with nine setae in two groups in addition to anterio-distal group of nine simple setae. Palm slightly convex, with one strong long palmar robust seta, one short supporting robust seta on inner surface, with three robust setae with lateral projections on outer surface; two simple setae under supporting robust seta in palmar corner. Dactylus reaching posterior margin of propodus, outer and inner margins with a row of three and five simple setae, respectively; nail short, 0.23 of total dactylus length ( Fig. 3).

Coxa of gnathopod II rectangular, with 12 setae along anterio-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 of basis length and 0.69 propodus length. Carpus with one group of four setae antero-distally. Propodus in gnathopod II larger than gnathopod I, trapezoid shape and broader than long; anterior margin

(P III–P VII)

with totally four setae in two groups in addition to antero-distal group of eight simple setae. Palm nearly convex, with one strong palmar robust seta, one supporting robust seta without lateral projections on inner surface, with two robust setae with lateral projections on outer surface; two setae under supporting robust seta in palmar corner. Dactylus is not reaching posterior margin of propodus, outer and inner margins of dactylus each with five simple setae. Nail length 0.25 of total dactylus length ( Fig. 3).

Coxa III rectangular, length to width ratio as 1.24: 1; antero-ventro-posterior margin with 10 simple setae. Coxa IV rectangular, length to width ratio as 1.36: 1, antero-ventroposterior margin with eight simple setae, posterior concavity shallow and approximately 0.1 of coxa width ( Fig. 4). Coxa V with anterior lobe, with four and one simple setae on anterior and posterior lobes, respectively. Coxa VI with anterior lobe, with one simple seta on anterior and posterior lobes each. Coxa VII with one simple seta ( Fig. 4).

Pereonites I–VI without setae. Pereonite VII with one simple seta along dorsal surface. Pereopod III: IV lengths ratio as 1.08: 1 ( Fig. 4). Dactylus IV short, length of dactylus 0.36 of propodus, nail shorter than pedestal ( Fig. 4). Pereopods V: VI: VII length ratios as 1: 1.26: 1.17, respectively. Pereopod VII 0.52 of body length. Pereopod bases V-VI each with eight groups of robust setae and pereopod basis VII with 12 simple setae along anterior margin, respectively. Pereopod bases V-VI with 13 and 14 simple setae and pereopod basis VII with eight groups of robust setae along posterior margin, respectively ( Fig. 4). Posteroventral lobe of ischium in pereopods V–VII weakly developed. Ischium, merus and carpus in pereopods V–VII with several groups of robust and simple setae along anterior and posterior margins; propodus of pereopod VII longer than these in V-VI, dactyli of pereopods V–VII with one robust and one short simple seta at the base of nail on inner margin, nail length of pereopod VII 0.29 of total dactylus length ( Fig. 4).

Epimeral plates I–III ( Fig. 5) with angular postero-ventral corner, anterior and ventral margins convex; postero-ventral corners of plates I-III with one robust seta each, and with one, two and two simple setae posteriorly, respectively. Epimeral plates II-III with three and two robust setae along of ventral margins, respectively.

Pleonites I–III each with one to two simple setae along dorsal surface. Peduncle of pleopod I with two simple setae and two-hooked retinacles along of inner margin ( Fig. 5); peduncle of pleopod II with two-hooked retinacles at distal part of inner margin; peduncle of pleopod III with two-hooked retinacles and with one simple seta at distal part of inner margin; rami of pleopods I–III each with 10 to 14 articles ( Fig. 5).

Laterally, urosomites I-III with one robust seta, two robust setae and one simple seta and without setae, respectively. Peduncle of uropod I with five and two large robust setae along dorso-lateral and dorso-medial margins, respectively. Outer ramus as long as inner ramus; inner ramus with three groups of robust setae laterally and five robust setae distally; outer ramus with four groups of seven robust setae laterally and five robust setae distally ( Fig. 5). Inner ramus in uropod II longer than outer, both rami with lateral and distal long robust setae ( Fig. 5). Uropod III long, almost 0.5 of body length. Peduncle of uropod III with five robust setae. Outer ramus biarticulated, distal article 0.19 proximal article. Proximal article of outer ramus bearing seven and eight groups of robust setae along inner and outer margins ( Fig. 5); distal article with simple setae laterally and four simple setae distally. Inner ramus short, with two robust and one simple distal setae. Telson longer than broad, lobes slightly narrowing; each lobe with three robust setae distally and with two plumose setae laterally ( Fig. 5).

Etymology – The species is named in honour of Professor Alireza Sari, University of Tehran, Iran, to acknowledge his many years of contribution to the zoology of Iran, especially his work on crustaceans.

Phylogenetic relationships and molecular divergence

We analysed 53 Niphargus species (63 individuals) based on 810 base pairs of the first fragment of the 28S ribosomal DNA gene. Two phylogenetic analyses (Bayesian inference and maximum likelihood) yielded similar topologies. The topology resulting from Bayesian inference analysis is presented in Figure 6. The newly described N. sarii sp. n. is nested within the main Iranian clade plus the specimen from Lebanon (which is juvenile and its identity could not be determined). This species shares an ancestor with N. hosseiniei , N. khayyami and N. sohrevardensis ( Fig. 6). Pairwise uncorrected Kimura 2-parameter genetic distances and patristic distances on a 28s maximum likelihood tree between all Iranian species and the Lebanon sample are presented in Table 2. The K2P genetic distances between the N. sarii and other species ranged between 0.60% and 10.80%, and the patristic distance is between 0.90% and 28.60%. The new species is genetically most similar to N. sohrevardensis (0.60% K2P and 0.90% patristic divergence in the studied 28 rDNA gene fragment) and the most divergent species from N. daniali , (10.08% K2P and 28.60% patristic divergence). Minimum interspecific distance was observed between two previously known species N. persicus and N. darvishi with the least divergence of 0.30% in both K2P and patristic divergence.