Niphargus khayyami, Hekmatara & Zakšek & Baladehi & Fišer, 2013

Hekmatara, M., Zakšek, V., Baladehi, M. Heidari & Fišer, C., 2013, Two new species of Niphargus (Crustacea: Amphipoda) from Iran, Journal of Natural History 47 (21 - 22), pp. 1421-1449 : 1423-1434

Niphargus khayyami sp. nov.

( Figures 3–6 )

Type locality

Ghoori-Ghaleh cave, Ravansar-Paveh road, Kermanshah Province, Iran. Coordinates: 34 ◦ 53, N, 46 ◦ 30, E ( Figure 1 ).

Material examined

Holotype is a 12.2-mm-long female, partially damaged. Paratypes include two partially damaged and smaller specimens.

Etymology

The species is named in honour of Omar Khayyám (1048–1131), Persian mathematician, astronomer, philosopher and poet. He is the author of one of the most important treatises on algebra written before modern times and he contributed to calendar reform. Outside Iran and Persian-speaking countries, Khayyám has had an impact on literature and societies through the translation of his works and their popularization by other scholars.

Diagnosis

(Part, based on females only.) Mid-sized niphargids with stout body. Pleonites I–III with up to three setae along the entire dorsoposterior margin. Epimeral plate II–III slightly inclined, posterior and ventral margins concave and convex, respectively; ventro-posterodistal corner distinct but not produced. Urosomite I posterodorsolaterally with one or two weak setae; urosomite II postero-dorsolaterally with two or three setae. Mouth parts common, maxilla I with two setae on inner lobe; on outer lobe are six multidenticulated and one unidenticulated spine. Telson deeply cleft, each lobe with three apical spines and up to one dorsal spine. Coxal I–IV plates deep. Gnathopods I–II ischium with distal setal group and with posterofacial setal group; propodi small and trapezoidal and rectangular, respectively. Dactyli of pereopods III–VI with one weak and two spiniform setae at the base of nail, dactylus VII with one weak and single spiniform seta at the base of nail. Pleopods with two retinacles.

Description of holotype

Head and trunk ( Figure 2 ). Body length up to 12.2 mm. Head length up to 9% of body length; rostrum absent. Pereonites I-VII without setae.

Pleonites I–III with up to three setae along the entire dorsoposterior margin. Epimeral plate II slightly inclined, posterior and ventral margins concave and convex, respectively; ventro-posterodistal corner distinct but not produced; along ventral margin three spiniform setae; along posterior margin four thin setae. Epimeral plate III inclined, posterior and ventral margin straight and slightly convex, respectively; ventro-posterodistal corner distinct but not produced; along ventral margin on one side four and on the other side five spiniform setae; along posterior margin four thin setae.

Urosomite I postero-dorsolaterally with one or two weak setae (left–right asymmetry); urosomite II postero-dorsolaterally with two or three setae (left–right asymmetry); urosomite III without setae. At the base of uropod I single strong spiniform seta.

Telson length: width ratio is 1: 0.80; cleft is 0.70 of length; telson margins straight and narrow apically. Telson spiniform setae (per lobe): three apical spiniform setae of up to 0.30 telson length; mesial and lateral margins without setae; dorsal surface with single spiniform setae. Pairs of plumose setae inserted mid-laterally.

Antennae ( Figure 3 ). Antenna I 0.45 of body length. Flagellum with up to 21 articles; each article with one aesthetasc. Peduncle articles in ratio 1: 0.80: 0.50. Proximal article of peduncle dorsodistally slightly produced. Accessory flagellum biarticulated; distal article shorter than one half of proximal article length.

Length ratio antenna I: antenna II as 1: 0.45. Flagellum of antenna II with nine articles; each article with setae and elongate sensilla of unknown function. Peduncle articles lengths 4: 5 is 1: 1; flagellum 0.70 of peduncle articles 4+5.

Mouthparts ( Figure 3 ). Labrum typical; inner lobes of labium longer than half of the outer lobes.

Left mandible: incisor with five teeth, lacinia mobilis with four teeth; between lacinia and molar a row of thick serrated setae, long seta at the base of molar. Right mandible: incisor processus with four teeth, lacinia mobilis with several small denticles, between lacinia and molar a row of thick serrated setae. Ratio of mandibular palp article 2: article 3 (distal) is 1: 1.25–1.30. Proximal palp article without setae; the second article with up to 10–12 setae; distal article with a group of five A setae; three groups of B setae; 21 D setae and four E setae.

Maxilla I distal palp article with six apical setae. Outer lobe of maxilla I with six pluri-toothed and one uni-toothed stout seta apically; inner lobe with two setae.

Maxilla II inner lobe slightly smaller than outer lobe; both of them setose apically and subapically.

Maxilliped palp article 2 with 10 rows of setae along inner margin; distal article with a dorsal seta and a group of small setae at the base of the nail. Maxilliped outer lobe with 11 flattened thick setae mesially and six serrated setae apically and subapically; inner lobe with four flattened thick setae apically and five serrated setae.

Coxal plates, gills and oostegites ( Figures 4 , 5 ). Coxal plate I deep and a parallelogram shape, anteroventral corner subrounded; anterior and ventral margin of coxa I with seven setae. Coxal plates II–III width: depth is 1: 0.70; anterior and ventral margin with 11 setae. Coxal plate IV width: depth ratio is 1: 0.80; posteriorly slightly concave (approximately 0.10 of coxa width); along anteroventral margin 14 setae. Coxal plates V–VI: anteriorly developed lobe; posterior margin with two or three setae. Coxal plate VII shaped like a half-egg with one posterior seta. Gills II–VI ovoid and reach up to the mid of basis, oostegites large ovoid, with long setae.

Gnathopod I ( Figure 4 ). Ischium with one submarginal seta and five or six posterodistal setae. Carpus 0.55 of basis length and 0.95 of propodus length. Anterior margin of carpus with the distal group of setae and additional seta; carpus posteriorly with transverse rows of setae proximally, a row of lateral setae; posteroproximal bulge large (one-third of carpus length), positioned proximally. Propodus trapezoid, palm convex and slightly inclined. Along posterior margin six rows of denticulated setae. Anterior margin with 12 setae in two groups in addition to anterodistal group with 13 setae. Group of three facial setae proximally of palmar spiniform seta; several groups of short setae on the inner surface present. Palmar corner slightly produced and with strong palmar spiniform seta, single supporting spiniform seta on inner surface and three denticulated thick spiniform setae on outer side. Nail length 0.33 of total dactylus length; along anterior margin one seta; along inner margin a row of short setae.

Gnathopod II ( Figure 4 ). Basis width: length is 1: 0.30. Ischium with two submarginal setae and four posterodistal setae. Carpus 0.60 of basis length and 1.10 of propodus length. Anterior margin of carpus with distal row of setae; carpus posteriorly with transverse rows of setae proximally and a row of lateral setae; posteroproximal bulge large (one-third of carpus length), positioned proximally. Propodus small (circumference measures up to 0.16 of body length) and larger than propodus of gnathopod I (1: 0.80). Propodus rectangular, palm convex and slightly inclined. Posterior margin with 12 rows of denticulated setae. Anterior margin with seven setae in three groups in addition to 11 anterodistal setae. Group of four facial setae proximally of palmar spiniform seta; individual surface setae present. Palmar corner with strong palmar spiniform seta, single supporting spiniform seta on inner surface and three denticulated thick spiniform setae on outer side. Nail length 0.25–0.30 of total dactylus length. Along anterior margin one seta; along inner margin few short setae.

Pereopods III–IV ( Figure 5 ). Lengths of pereopods III: IV equal to ratio 1: 0.95. Dactylus IV 0.40 of propodus IV; nail length 0.45 of total dactylus length. Dactyli III–IV with dorsal plumose seta; at the base of nail tiny seta and two spiniform setae. Pereopods V–VII ( Figure 5 ). Lengths of pereopods V: VI: VII is 1: 1.25: 1.25. Pereopod VII length 0.45–0.50 of body length.

Bases V–VII length: width ratios are 1: 0.78, 1: 0.73 and 1: 0.73, respectively; posterior margins straight to convex, with small distal lobes; posteriorly 14, 11 and 10 thin flexible setae respectively; anteriorly 8, 7 and 8 groups of slender spiniform setae respectively. Dactylus VII length 0.25 of propodus VII length; nail length 0.35 of total dactylus length. Dactyli V–VI dorsal plumose seta; at the base of nail a tiny seta and two spiniform setae; dactylus VII with dorsal plumose seta; at the base of nail a tiny seta and one spiniform setae.

Pleopods and uropods ( Figure 6 ). Pleopods I–III with two hooked retinacles. Bases of pleopods II–III with distinct stout setae. Pleopod II rami of 10–13 articles each.

Uropod I protopodite with four dorsolateral spiniform setae and two dorsomedial spiniform setae. Exopodite: endopodite lengths is 1: 1.08; rami straight. Endopodite with four individual stout setae and five apical spiniform setae. Exopodite with four spiniform setae in three groups; apically four spiniform setae.

Uropod II exopodite: endopodite lengths is 1: 1.05.

Uropod III up to 0.25 of body length. Protopodite with one lateral seta and six apical spiniform setae. Endopodite 0.50 of protopodite length, apically with three spiniform setae; laterally without setae. Exopodite of uropod III rod-shaped, distal article 0.10 of the proximal article length. Proximal article with six groups of plumose, thin flexible and spiniform setae along inner margin and five groups of thin flexible and spiniform setae along outer margin. Distal article with two setae groups along inner margin; apically four setae.

1mm

Variability

Males unknown. Smaller specimens have fewer spines. Some of diagnostic characters (below) are rare among niphargids.

Remarks and affinities

In subterranean amphipods, males can be rare and in such cases females are used for description (e.g. Culver et al. 2010). Even though we have no information on male morphology and possible sexual dimorphism, N. khayyami can be unambiguously defined by the combination of few characters: multidentate spines on outer lobe of maxilla I, posterofacial setae on ischium of both gnathopods, single seta on dactylus of both gnathopods, deep coxal plates, inclined epimeral plates with straight to slightly concave margins, number of retinacula and pattern of spines on telson. The shape of coxal plates and gnathopods coupled with single dactylar seta on gnathopods aligns N. khayyami with a morphological group of species that have been traditionally treated as the carpathicus species group ( Straškraba 1972). More detailed comparison with other species sharing these three morphological characteristics is presented in Table 1. Unfortunately, some characters are not discussed in original descriptions (e.g. number of retinacles) and sometimes the appendages bearing traits of interest are not illustrated (e.g. ischium of gnathopods). Despite all missing data, an exclusive diagnosis can be made.

We focus our discussion on some diagnostic traits. A rare trait in Niphargus worth emphasizing is the posterofacial group of setae on ischium of both gnathopods. The character was first mentioned by Karaman (1984a). Since then many species presented in Table 1 have been redescribed and only a few cases remain ambiguous. With the exception of N. galvagnii , the posterofacial setae on ischium of both gnathopods have not been reported. This trait is the most frequent among distinct, large-bodied species with long appendages and large gnathopods (see data on web-base http://niphargus. info/morpho-database/). All the species are remarkably different from N. khayyami in body size and setal patterns of gnathopods and pleon. In addition, this trait was found also in N. spinulifemur and N. hvarensis ; both species differ from N. khayyami by being more slender, by having many more spiniform setae on the telson as well as by having more numerous dactylar setae on gnathopods.

The telson is important in niphargid taxonomy. Our observations indicate that numbers and position of spiniform setae on the telson are rather stable. Molecular analyses confirmed several taxonomic conclusions that had been based on minor differences in position and number of spiniform setae on telson ( Karaman 1952; Fišer et al. 2010). Niphargus khayyami has a rather unique distribution of telson spines, not found among species included in the comparison ( Table 1).

Apart from species treated in Table 1, N. khayyami resembles N. ictus Karaman 1986 from Israel in several aspects. Similarities include multidentate spiniform setae on outer lobe of maxilla I, shape of gnathopods, coxal and epimeral plates, more than one spiniform seta along inner margin of dactyli V–VI. Nevertheless there are several differences: antenna I measures 0.75 of body length (0.45 in N. khayyami ); dactyls of gnathopods I–II in N. ictus have more than single seta (only one in N. khayyami ); dactyli III–IV have single spiniform seta along inner margin (two in N. khayyami ) and telson has only apical spines (also dorsal spines in N. khayyami ). Geographically close N. nadarini found from Iraq resembles N. khayyami by armature of pereopod

N. romanicus Dobreanu Romania 0 0 0+1 4 A+L+M 0 1

and Manolache, 1942

N. similis Karaman and Italy 0 0 0 3 A+L 0 1 Ruffo, 1989

N. strouhali Schellenberg , Austria 1 0 1 3 A+L 0 1

1933

N. variabilis Dobreanu , Romania 0 0 0 3–4 A+L+M 0 1 Manolache and Puscariu,

1953

N. khayyami sp. nov. Iran 1 1 0 3 A+D 1 0 Note : the most evident discriminating characters are indicated in bold type .

∗ In comparison are included species that share deep coxal plates (dorsoventral length equal to or longer than anteroposterior length), similarly shaped grnathopods I–II and single seta on dactylus of gnathopod I–II. Comparison with N. itus is discussed in text.

† Source of information on species morphology is original description of species. Other relevant sources include monographs of Karaman, 1993 and Cărăuşu et al., 1955 for Italian and Romanian species, respectively.

1 Inner multi-denticulate, other bi- or tri-denticulate = 0, all multi-denticulate = 1.

2 Absent = 0, present = 1.

3 Inclined, distoposterior margin well defined = 0, subrounded = 1.

4 A, apical; D, dorsal; M, mesial; L, lateral; terminology by Fišer, Trontelj et al. (2009).

5 Single spiniform seta along inner margin = 0, at least two spiniform setae along inner margin = 1.

6 Two = 0, more than two = 1.

7 cited in Motas, Dobreanu and Manolache 1939.

dactyls III–IV, but differs in the setal pattern of dactylus of gnathopods I–II (several setae in N. nadarini versus single seta in N. khayyami ) and type of spines on outer lobes on maxilla I (only inner spine multidenticulate in N. nadarini ) ( Karaman 1986).

Niphargus khayyami is currently defined solely by its morphological characteristics (i.e. morpho-species), which remarkably exceed the amount of morphological differentiation of many species (e.g. Fišer et al. 2006). Additional individuals, however, would be welcome to prove that diagnostic traits are not polymorphic (e.g. Wiens and Servedio 2000). Implicit evidence for its taxonomic status provides spatial isolation. The distance to the nearest morphologically similar species ( N. ablaskiri and N. inermis ) is approximately 600 km north ( Georgia), which exceeds the expected maximum range size ( Trontelj et al. 2009; Zagmajster et al. 2010).

Figures

Figure 1. Distribution of Niphargus species in the Middle East and Iran.

Figure 2. Niphargus khayyami sp. nov., holotype, lateral view. The appendages indicated with dashed lines are reconstructed from the other side of the animal.

Figure 3. Niphargus khayyami sp. nov., holotype: antennae and mouthparts.

Figure 4. Niphargus khayyami sp. nov., holotype: gnathopods I–II and epimeral plates.

Figure 5. Niphargus khayyami sp. nov., holotype: pereopods III–VII.

Figure 6. Niphargus khayyami sp. nov., holotype: pleopod, uropods and telson.