Niphargus lorestanensis, Esmaeili-Rineh, 2018

Esmaeili-Rineh, Somayeh, 2018, A new data of freshwater amphipod of genus Niphargus Schiödte, 1849 from Lorestan Province in Iran, Zootaxa 4531 (2), pp. 242-250 : 243-246

Niphargus lorestanensis sp. nov.

Type material and material examined. Holotype: male specimen (10 mm) from Shol-Abad Spring , Lorestan Province, Iran . Holotype and two juvenile paratypes are stored under catalogue number ZCRU Amph. 1029 in the Zoological Collection , Razi University, Iran ( ZCRU) .

Type locality. Shol-Abad Spring , 80 km to Aligudarz City, Lorestan Province, Iran (33°09′N 49°5′E) .

Diagnosis. Niphargus lorestanensis is diagnosed by multiple supporting robust setae on the gnathopods I–II propodi, rectangular propodi of gnathopods I–II. Also, maxillar I palpus is normal and reach to the tip of the outer lobe and dactyli of both gnathopods I–II are not reaches to the posterior margin of propodus.

Description of holotype. Total length of specimen 10 mm. Head length 9% of body length. Antennae I ( Figure 1A ) 0.45 of body length. Peduncular articles 1–3 progressively shorter; peduncular articles 2: 3 in ratio 1.8: 1; main flagellum with 22 articles; accessory flagellum bi-articulated, reaching 1/3 of article 4 of main flagellum, with one and three simple setae, respectively ( Figure 1A ). Peduncular article 4 of antennae II as long as article 5, with five and four groups of simple setae, respectively; flagellum with nine articles. Length of flagellum: length of peduncle articles 4 + 5 as 0.5: 1( Figure 1B ).

Labium ( Figure 2A ) with inner lobes and setae on the tip of the lobes. Inner plate of maxilla I with two long simple setae; outer plate with seven robust setae with 4-5-5 and more than 5 lateral projections; palp bi-articulated, as long as outer lobe, with two distal simple setae ( Figure 2B ). Both plates of maxilla II with numerous distal simple setae and three lateral simple setae ( Figure 2C ). Maxilliped with short inner plate bearing three distal robust setae intermixed with six distal simple setae and three simple long lateral setae subdistally; outer plate exceeding half of the palp article 2, with nine robust setae along inner margin and five 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 and two setae at the base of nail, nail shorter than pedestal ( Figure 2D ).

Mandibular palp articles 1: 2: 3 ratios as 1: 2.1: 2.35. The proximal article with no setae, the second article with 12 setae along inner margin and the third article with one group of two A-setae, three groups of B-setae, no Csetae, 18 D-setae and four E-setae ( Figure 2E ). Left mandible having pars incisive with five teeth, lacinia mobilis with four teeth and nine setae with lateral projections between lacinia and triturative molar ( Figure 2F ). Right mandible having pars incisiva with four teeth, lacinia mobilis pluritoothed and six setae with lateral projections between lacinia and triturative molar ( Figure 2G ).

Coxa of gnathopod I rectangular, slightly rounded, with six setae along ventro-posterior margins. Basis with setae in groups and single setae along anterior and posterior margins; posterior margins of ischium and merus with one posterior group of setae each. Carpus 0.58 of basis length and 0.9 propodus length. Carpus with one group of four setae antero-distally, and rows of setae on the posterior bulb. Propodus of gnathopod I, trapezoid shape and broader than long; anterior margin with nine setae in two groups in addition to antero-distal group of seven simple setae. Palm convex, with one strong palmar robust seta, two supporting robust setae without lateral projections on inner surface, and two robust setae with lateral projections on outer surface; two setae under supporting robust setae in palmar corner. Dactylus not reaching posterior margin of propodus, outer and inner margins of dactylus with three simple setae. Nail length 0.3 of total dactylus length ( Figure 1C ).

Coxa of gnathopod II rectangular, longer than broad, antero-ventro-posterior margins with eight simple 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, a bulge with long simple setae; carpus 0.6 of basis length and 0.88 of propodus length. Propodus broader than long; anterior margin with seven setae in two groups in addition to anterodistal group of five simple setae. Palm slightly convex, with one strong long palmar robust seta, two short supporting robust setae on inner surface. Dactylus not reaching posterior margin of propodus, outer and inner dactylar margins with four and five simple setae, respectively; nail short, 0.28 of total dactylus length ( Figure 1D ).

Coxa III rectangular, length to width ratio as 1.42: 1; antero-ventro-posterior margin with six simple setae. Coxa IV rectangular, ventro-posterior margin with five simple setae, posterior concavity shallow and approximately 0.1 of coxa width ( Figure 3 A-B). Coxa V with anterior lobe, with two and one simple setae on anterior and posterior lobes, respectively. Coxa VI with anterior lobe, with one simple seta on anterior lobe. Coxa VII half-ovoid, with one simple posterior seta ( Figure 3 C-E).

Pereopod III: IV lengths in ratio as 1.06: 1 ( Figure 3 A-B). Dactylus IV short, length of dactylus 0.33 of propodus, nail shorter than pedestal ( Figure 3B ). Pereopods V: VI: VII length ratios as 1: 1.14: 1.17. Pereopod VII 0.5 of body length. Pereopod bases VI-VII with five and six groups of robust setae along posterior margins and each with seven simple setae along anterior margins, respectively ( Figure 3 C-E). Pereopod base V with six groups of robust setae along anterior margin and with seven simple setae along posterior margin, respectively ( Figure 3 C- E). Postero-ventral lobe of ischium in pereopods V–VII 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 0.16 of total dactylus length ( Figure 3 C–E).

Pereonites I–VII without setae. Pleonites I–III each with 1-3 simple setae along dorsal surface. Epimeral plates I–III ( Figure 4D ) with angular postero-ventral corners, anterior and ventral margins convex; postero-ventral margins of plates I–III with three, four and four setae posteriorly, respectively. Epimeral plates II–III with two and three robust setae along of ventral margins, respectively. Peduncle of pleopods I–III with two-hooked retinacles. Peduncle of pleopod I with two simple setae along of outer margin. Peduncle of pleopod II with two simple setae along of inner margin ( Figure 4 A–C); rami of pleopods I–III each with eight to 15 articles ( Figure 4 A-C).

Urosomites I–III with two, two and without robust setae dorso-laterally, respectively. Urosomite I with one robust seta at the base of uropod I. Peduncle of uropod I with eight and three large robust setae along dorsolateral and dorsomedial margins, respectively. Inner ramus of uropod I longer than outer ramus (ratio 1.11: 1); inner ramus with four groups of robust setae laterally and five robust setae distally; outer ramus with two groups of six robust and one simple setae laterally and five robust setae distally ( Figure 4E ). Inner ramus in uropod II longer than outer, both rami with lateral and distal long robust setae ( Figure 4F ). Uropod III long, almost 0.4 of body length. Peduncle of uropod III with six robust setae. Outer ramus bi-articulated, distal article measures 0.13 of the proximal article. The proximal article of outer ramus bearing six groups of robust setae along each inner and outer margins ( Figure 4G ); distal article with simple setae laterally and four simple setae distally. Inner ramus short, with two robust distal setae. Telson two times longer than broad slightly; each lobe with three robust setae distally, with two plumose setae laterally ( Figure 4H ).

Etymology. The name “lorestanensis” refers to Lorestan Province ( Iran), where the species was found.

Remarks and affinities. According to Esmaeili-Rineh et al. (2015b), the Shol-Abad and Abrahmeh populations form a single species based on 28s rDNA, CO1 and H3 sequences. Unfortunately, due to the lack of sample, there is no information about morphological characters of Abrahmeh population. It seems N. lorestanensis sp. nov. has a sister relationship with N. darvishi and N. persicus ( Esmaeili-Rineh et al. 2015a) . Niphargus persicus differs from N. lorestanensis in the ratio of maxillar palpus to outer lobe, the shape of gnathopod I propodi, the status of dactyli in gnathopods I to II.

The survey of diagnostic characters suggests that several Iranian species ( N. bisitunicus , N. sharifii and N. ilamensis ) bear multiple supporting robust setae on both of gnathopods propodi ( Esmaeili-Rineh et al. 2015a), however, the first two species have rectangular shaped propodi. Niphargus lorestanensis is diagnosed from N. bisitunicus in equal length of maxillar palpus to outer lobe, pluritooth robust setae on the outer lobe of maxilla I, the lack of lateral robust setae on each telson lobe and the situation of dactyli in gnathopods I and II. Niphargus sharifii has many similarities to the new species; however, N. lorestanensis is different in the number of robust seta in dorsal margin of urosomites I–III, the status of the dactyli to the posterior margin of the propodus in both gnathopods and the number of robust seta in outer margin of the propodi in gnathopods I–II ( Esmaeili-Rineh et al. 2015a).

Third diagnostic character is observed only in N. sharifii and N. alisadri between the Iranian species. The new species is distinguished from N. alisadri by the shape of propodus in gnathopod II, the number of robust setae in dorsal margin of urosomites I–II, the number of lateral robust seta on each telson lobe and the ratio of distal to proximal articles in the outer ramus of uropod III ( Esmaeili-Rineh & Sari 2013, Esmaeili-Rineh et al. 2015a).

The last diagnostic character, in addition to the new species, is also seen in N. sarii , N. hosseiniei and N. ilamensis ( Esmaeili-Rineh et al. 2017b; Esmaeili-Rineh et al. 2018). But in all of them except, N. ilamensis , the dactyli of gnathopod I are reaching to the posterior margin of the propodus. Therefore, N. lorestanensis is similar to (this character) only N. ilamensis . The new species shares traits with N. ilamensis , including the number of distal robust setae on each telson lobe, the ratio of inner to outer ramus of uropod I and the ratio of distal to proximal article in outer ramus of uropod III. However, N. lorestanensis is separated from N. ilamensis by the lack of robust setae on dorsal margin of urosomite III, the shape of gnathopod II propodi and the ratio of maxillar palpus to outer lobe.

Figures

FIGURE 1. N. lorestanensis sp. nov., Holotype, male, 10 mm. Shol-Abad. Scale for AI, AII, GNI and GNII represents 1 mm.

FIGURE 2. N. lorestanensis sp. nov., Holotype, male, 10 mm. Shol-Abad. Scale for LMND and RMND represents 0.25 mm; MNDP, MX I, MX II, MXP and LB represents 0.5 mm.

FIGURE 3. N. lorestanensis sp. nov., Holotype, male, 10 mm. Shol-Abad. Scale for P III, P IV, P V, P VI and P VII represents 1 mm.

FIGURE 4. N. lorestanensis sp. nov., Holotype, male, 10 mm. Shol-Abad. Scale for EP I-III and T represents 0.5 mm. Scale for PL I–III and UI–UII represents 1 mm; Scale for UIII represents 2 mm.