Niphargus keeleri, Zamanpoore & Bakhshi & Sadeghi & Malek-Hosseini, 2020

Zamanpoore, Mehrdad, Bakhshi, Yaser, Sadeghi, Saber & Malek-Hosseini, Mohammad Javad, 2020, Niphargus keeleri n. sp., a new cave Amphipod (Arthropoda: Crustacea) from the Zagros Mountains, Iran, Journal of Natural History (J. Nat. Hist.) 53 (43 - 44), pp. 2621-2635 : 2622-2633

Niphargus keeleri sp. nov.

( Figures 1–6)

urn:lsid:zoobank.org:pub:14D5A709-FDDB-4D94-8AE8-F8AC0181D845

Material examined

Holotype. Male, body length 8 mm, October 2011, ZM-CBSU Amph 3418, coll. M.J. Malek- Hosseinie and Y. Bakhshi. Locus typicus: Keeler spring, Keeler Cave (31.283°N, 50.583°N), Keeler Valley , 140 km north-west of Yasuj (Kohgiluyeh and Boyerahmad Province); altitude 1610 m . Paratypes: two males and one female; same date and locality, FAIC 112001 , coll . M .J. Malek-Hosseinie and Y. Bakhshi. Allotypes: seven males and one female, July 2012, same locality, FAIC 112002 , coll . M .J. Malek-Hosseinie and Y. Bakhshi . All specimens including type series are kept in the Aquatic Invertebrate Collection of the Museum of Fars Research Centre of Agriculture and Natural Resources ( FAIC), Shiraz, Iran . The holotype is deposited in the Zoological Museum of the University of Shiraz ( ZM-CBSU) .

Diagnosis

This new species can be distinguished from other niphargid species by a combination of characters. These include long and slender pereopod III–VII, no spine on dorsal surface of telson, short second article of uropod III exopodite, distinct irregular trapezoid palm of gnathopod II, a row of 16 fine setae attached on inner margin of dactylus of gnathopods I and II, not sharply pointed epimeral plates I–III, one spine on distal end of urosomite I, long E-setae in third segment of mandible palp, pleopods I–III with long setae, palmar corner of gnathopod I and II with 1–2 and 1 small spiniform setae, respectively.

Etymology

The new species is named after the type locality: Keeler Cave , Yasuj, Iran .

Description

The description is based on examination of the holotype, and of two male and one female dissected paratypes.

Male

Head and trunk. Body slender, length up to 16 mm ( Figure 1). Head length up to ca 6% of body length; head with a short rostrum. Lateral cephalic lobes sub-rounded ( Figure 2 (e)).

Pleonites I–III. Smooth, epimeral plate I distal margin convex, epimeral plate II distal margin convex, with 2–3 short spines, antero-distal corner convex; epimeral plate III postero-distal corner moderately pointed, distal margin straight to moderately convex, anterior distal corner convex, 2–3 short spines along ventral margin of epimeral plate II and III ( Figure 2 (b)).

Urosomites. Urosomite I with 1–2 very short setae at dorsolateral posterior margin, urosomite II–III with combination of 2–4 small spines and 1–2 short setae on each side. A spine is seen ventrodistally on urosomite I ( Figure 2 (a)).

Telson. Laminar deep cleft, moderately elongated, distally narrower; length:width ratio 1.2; 3 apical spines in each lobe, of up to 0.35 of telson length ( Figure 2 (f)).

Antenna I. Long (0.5–0.65 of body length), main flagellum with 28–32 articles ( Figure 2 (c)); accessory flagellum biarticulate. Antennae I length is more than twice that of antenna II, ca. 2.2 times.

Antenna II. Articles 4 and 5 with a few bundles of short setae (as long as the width of the article) on lateral, and a few longer on distal margin (almost twice longer than the width of the article). Length of peduncle article 5 slightly longer than article 4 (1.1–1.2); flagellum short (as long as ca. 0.4 length of peduncle articles 4 and 5), having 6 articles; gland cone short (reaching to 1/2 the length of article 3) and blunt ( Figure 2 (d)).

Mouthparts. Labrum slightly longer than broad; labium inner lobes well developed, as long as 2/3 of outer lobe ( Figure 3 (h)).

Maxilla I (left and right). Inner plate with 2–3 distal setae; outer plate with 7 toothed spines each with 0–3 strong lateral teeth; palp distal article with 2 long apical setae, slightly shorter than or as long as the distal article ( Figure 3 (e,f)).

Maxilla II. Inner plate shorter and broader than outer; both with apical setae, inner plate with 1 subapical seta ( Figure 3 (g)).

Maxilliped. Outer lobe short, with 1–3 distal smooth-topped spines and 6 apical and 2 lateral setae, inner plate with a row of smooth spines along inner margin extended to the distal margin; palp well developed; 3 small setae at base of nail ( Figure 3 (d)).

Left mandible. Incisor with 6 teeth of increasing size, lacinia mobilis bifurcate; a row of 8 serrated spines of similar lengths between lacinia mobilis and molar process, a bundle of a few fine seta at inner base of molar process ( Figure 3 (a)).

Right mandible. Incisor with 3 teeth, lacinia mobilis bifurcate; a row of 8 serrated spines between lacinia mobilis and molar process ( Figure 3 (b)).

Mandible palp first article without seta, second article with 11 strong setae, almost as long as article 3; article 3 subfalciform, with 19 D-setae along inner margin and 5 long Esetae, 5 A-setae, and 4 rows of B-setae (2-2-2-2) ( Figure 3 (c)).

Gnathopod I. Coxal plate trapezoid, slightly longer than broad, antero-ventral corner subrounded with 3 setae, 1 seta at mid-ventral margin. Basis proximally narrower, dilated at posterior 1/3, with a row of 9 grouped long setae in anterior margin and 2 groups of 4 and 9 long setae at the dilation angle, 5 setae at postero-distal and 1 seta in antero-distal corner; carpus postero-proximally dilated with a bundle of setae, ischium with a group of 6 setae at postero-distal corner, merus posterior margin with a row of 11 setae with increasing length, and 2 long spines; carpus postero-distal and lateral margins with parallel rows of long setae, a few short setae on anterior distal corner; propodus slightly longer than broad, with a row of 9 transverse groups of setae along posterior margin, palm convex with 1 strong palmar robust seta and 1–2 small spiniform setae; posterior margin with 10 rows of setae; anterodistal corner with 5 setae; a row of very short setae on palmar surface; dactylus reaches posterior margin of propodus, with 3 single median setae along outer and 16 setae along inner margin ( Figure 4 (a)).

Gnathopod II. Coxal plate quadrilateral, longer than broad, antero-ventral corner subrounded, 8 very short setae along antero-distal and ventral margins, 1 single stouter seta at postero-ventral corner; basis 1.4 times longer than and more slender compared to gnathopod 1, 1 long seta in proximal anterior margin and a group of 9 long setae at the dilation angle; ischium with 7–8 postero-distal setae; merus with 3 posterior submarginal setae; carpus as long as or slightly shorter than propodus, 2 parallel rows of long setae on posterodistal and lateral margins, anterior distal corner with a few short setae; propodus irregular trapezoid quadrilateral, nearly as long as broad, with a row of 12 transverse groups of setae along posterior margin; palm convex with 1 strong palmar robust seta and 1 small spiniform seta; posterior margin with 12 rows of setae; antero-distal corner with 6–7 setae; groups of 1–3 setae on palmar surface; dactylus reaches posterior margin of propodus, with 2 single median setae along outer and 16 setae along inner margin ( Figure 4 (b)).

Pereopods III–IV. Pereopod III ( Figure 5 (a)) slightly shorter than IV ( Figure 5 (b)); dactyli III–IV short with a few dorsal simple setae and 1 tiny spine at nail base; ratios of the length of nail:dactylus and dactylus:propodus are 0.48 and 0.50 for pereopod III, and 0.49 and 0.51 for pereopod IV; basis long, the ratio of basis length to the whole appendage length is ca. 0.3 in pereopod III and IV; bases are subcircular in PIII and quadrilateral in PIV.

Pereopods V–VII. Length of pereopods V:VI:VII is 1:1.24:1.20; length of pereopod VII:body length: 0.6; bases length:width ratio of pereopods V–VII: 1:0.51, 1:0.47, 1:0.53; posterior margins in PV and PVI straight, slightly convex in pVII, with 8–10, 9–13 and 7–9 short simple setae, respectively; postero-distal corners with small lobes; anterior margin with 6– 7 short robust setae; ischium in pereopods V–VII with developed postero-ventral lobe; propodus of pereopod VII as long as in pereopod VI; dactylus: propodus length in pereopod VII is 0.28; nail:total dactylus length 0.37. Dactyli V–VII with a single dorsal seta; single tiny spine at the base of nail ( Figure 5 (c–e)).

Pleopods. Pleopods I–III distally with 2-hooked retinacles at inner margin; rami of pleopods I–III with 13–17 articles each ( Figure 6 (a–c)).

Uropods. Uropod I peduncle with 4 dorso-lateral spines; peduncle with 3 spines on distal margin; endopod:exopod length 1:1.01; endopod with 2 lateral and 4 apical slender spines; exopod with 3 lateral single spines, parallel, with 2 groups of 2 spines each; 4 apical spines ( Figure 6 (d). Uropod II endopod:exopod length 1:1.03; peduncle with 3 spines on distal margin; endopod with 2 lateral and 2–3 apical slender spines; exopod with 2 apical spines ( Figure 6 (e)).

Uropod III of moderate size, 0.2 of body length; peduncle with 1–3 apical spines and 1 seta, no lateral setae. Endopod short, 0.4 of the protopod length; exopod proximal article with 5 groups of 4 spines along inner margin and 4 groups of 4 spines along outer margin; distal article length 0.1 of the proximal, distal article with 3 lateral setae and 2 very short apical setae ( Figure 6 (f)).

Female

No significant sex differences were recognised and the female sample showed only a few dissimilarities with the male holotype and paratypes.

Antennae I main flagellum with 26 articles; antenna II article 4 has bundles of short setae (longer than the width of the article) on lateral, and still longer on distal, margin, length of peduncle article 5 slightly shorter than article 4, flagellum having 6 articles, longer than peduncle articles 4 and 5, gland cone longer (longer than 1/2 the length of article 3); gnathopod I propodus as long as broad; and gnathopod II carpus not dilated posteriorly and having few setae.

Ecology

This cave is almost straight, and about 1000 metres long. Its entrance is relatively large and contains no well inside. In rainy seasons, Keeler Cave is filled with a large amount of water and the water comes streaming out of the cave, but in dry seasons (e.g. at the end of spring, and in summer) there is only a small stream coming from a relatively large pool at the end of the cave, making several smaller pools of various sizes in some parts of the cave. The large pool at the end of the cave, with a maximum depth of about 150 cm, is a permanent pool, and the Niphargus specimens were collected from its edges. The floor and walls of the cave are always coated with a thin layer of mud. The air temperature inside the cave was 12.7°C; the humidity was measured at 90%. Water temperature was 12°C, pH was 7.2–7.7 and CO2 concentration was measured as 4 ppt. We found a few beetles, woodlice and spiders and some colonies of bats in the Keeler cave.

Remarks

Most of the more than 350 species of Niphargus are narrowly endemic. In accordance with common features of the genus, there are distinct differences separating populations in various geographic regions. A comparison of closely related species with the new species reveals these differences.

Compared to N. khayami , the new species has a longer antenna I and longer gland cone in antenna II, maxilla I inner plate with 2 distal setae while there are 6 in N. khayami , and distal palp with only 3 apical setae vs 6 in N. khayami ; gnathopod II propodus is trapezoid, vs rectangular in N. khayami ; pereopods V–VII are longer compared to body length; lacinia mobilis in mandible is bifurcate; maxilliped has 3 small setae at base of palp nail, and posterior margin of distal article has no setae.

Antenna I is longer compared to N. khwarizmi ; maxilla I inner plate has 2 distal setae, vs 6 in N. khwarizmi ; mandible Lacinia mobilis is bifurcate; and there are 5 E-setae on mandible palp article 3; maxilliped has 3 small setae at base of palp nail, and posterior margin of distal article without setae; pereopods V–VII are longer compared to body length; all segments of pleopods have long setae; distal article of uropod III exopod is short; no small spine is found on dorsal surface of telson.

The new species has also a longer antenna I and antenna II gland cone compared to N. alisadri . The other difference is in the maxilliped, with 3 small setae at base of palp nail, article 3 with no medial long seta in outer margin, and palp of terminal article with no seta in outer margin. Maxilla II inner plate has no lateral simple setae; gnathopods I and II have only 1 short supporting robust seta on inner surface of palmar corner; all segments of pleopods have long setae; distal article of uropod III exopodite is short. Telson has no spine on dorsal surface.

Niphargus keeleri is different from N. daniali in having a bifurcate mandible lacinia mobilis (pluriteeth in N. daniali ); mandibular palp first article has no setae; maxilla I inner plate has 2 distal setae (vs 8 in N. daniali ); palp distal article has 3 long apical setae (vs 5 in N. daniali ); inner plate of maxilla II has no lateral setae; maxilliped has 3 small setae at base of palp nail, and postero-distal margin of palp second article has no setae; palmar corner of gnathopods I and II have only 1 short supporting robust seta on inner surface; pereopods III–VI are generally much slenderer (vs strong in N. daniali ); pereopod III is slightly longer than IV (shorter in N. daniali ); dactyli of pereopods V–VII without seta in inner margin at the base of nail; all segments of pleopods have long setae; uropod III is generally longer and exopod distal article is short; telson has no spine on dorsal surface and 3 apical spines (vs 4 in N. daniali ); postero-distal corners of epimeral plates I–III are acuminated.

Compared to N. bisitunicus , in the new species second article of mandibular palp has 11 long setae (vs 7 in N. bisitunicus ), third article has 19 D-setae (vs 15 D-setae), 5 A-setae (vs 2 A-setae) and 4 rows of double B -(vs 2 single B-setae), and setae are generally much longer, especially the E-setae; maxilliped has 3 small setae at base of palp nail (vs 1 in N. bisitunicus ); propodi of gnathopod I and II are trapezoid (vs rectangular); gnathopod II has 1 long seta in proximal anterior margin (vs 3 short setae in N. bisitunicus ); pereopods V–VII bases are less slender, postero-distal corner is produced in P6 and there is no seta at the base of nail of dactyli inner margins; all segments of pleopods have long setae; rami of pleopods I–III have 13–15 articles (vs 7–10 in N. bisitunicus ), and are in total longer than peduncles; distal article of uropod III exopod is short; telson has no spine on dorsal surface; and postero-distal corners of epimeral plates I–III are slightly acuminated (vs sharply acuminated in N. bisitunicus ).

The following differences can be recognised in N. keeleri vs N. borisi , the geographically closest species. Second article of mandibular palp has 11 long setae (vs 4); third article with 19 D-setae (vs 10 D-setae), 5 A-setae (vs 2 A-setae), 4 rows of double B-setae (vs 2 single B-setae) and 5 E-setae (vs 4 E-setae). Setae are generally much longer, especially the E-setae. Inner plate of maxilla I has 2 long simple setae (vs 1 in N. borisi ); maxilliped has 3 small setae at base of palp nail (vs 1); dactylus of gnathopod I has 3 setae on outer margin (vs 4); propodus of gnathopod II is trapezoid (vs rectangular in N. borisi ); dactylus with 2–3 setae on outer margin (vs 1 in N. borisi ). Bases of pereopods V–VII are more slender; postero-distal corner is produced in pereopod 7, and there is no seta at base of nail of dactyli inner margin. All segments in pleopods shows long setae; peduncle of pleopod II has no long seta on distal surface, and rami of pleopod I–III have 13–15 articles (vs 7–9 in N. borisi ). Urosomite I has 1 robust setae at base of uropod I (vs 2 in N. borisi ); uropods I–III are long, so that peduncle of uropod I reaches the end of urosomite III (in N. borisi it reaches only to the end of urosomite II); peduncle of uropod III has 3 distal robust setae (vs 8 in N. borisi ); no spine can be seen on dorsal surface of telson.

Niphargus keeleri can be distinguished from N. darvishi by having no lateral seta on inner plate of maxilla II; 11 strong setae on second article of mandibular palp (vs 6), and no disto-lateral setae; no setae on outer margin of distal article in maxilliped palp; a propodus which is longer than broad in gnathopod I and II (vs much broader in N. darvishi ); less slender bases of perepod V–VII; longer setae on all segments of pleopods; long uropod I (so that peduncle reaches the end of urosomite III while it reaches only to the end of urosomite II in N. darvishi ); and slightly acuminated postero-distal corner of epimeral plates I–III (vs sharply in N. darvishi ).

Compared to N. shari fi, N. keeleri has a second article of mandibular palp with 11 long setae (vs 8), a third article with 19 D-setae (vs 25 D-setae), 5 A-setae (vs 3) and 4 groups of B-setae (vs 6 groups); its setae are generally much longer. Gnathopod I and II propodi are trapezoid (vs rectangular in N. shari fi), gnathopod I with 2 small supporting spines on palmar corner (vs 3 on outer and 4 on inner surface in N. shari fi); gnathopod II with 1 small supporting spine on palmar corner (vs 3). Distal article of maxilliped palp has no setae on outer margin; pereopods are longer in comparison with body length; postero-distal corner produced in P6 and P7; all segments of pleopods have long setae; uropod I is long, so that peduncle reaches the end of urosomite III (reaches to 2/3 of urosomite III in N. shari fi).

The new species can be distinguished from N. kermanshahi by these characters: second article of mandibular palp has 11 long setae (vs 8), third article has 19 D-setae (vs 15 Dsetae), 5 A-setae (vs 3 in N. kermanshahi ), 4 groups of B-setae (vs 3 groups in N. kermanshahi ). Gnathopod I has 2 small supporting spines on palmar corner (vs 5); Gnathopod II has 1 small supporting spine on palmar corner (vs 5 in N. kermanshahi ). Inner plate of maxilla II has no lateral seta; distal article of maxilliped palp has no setae on outer and inner margins; pereopods are longer in comparison with body length; basis of P7 is not rectangular, distal article of exopod in uropod III is short; telson has no spine on dorsal surface.

Niphargus keeleri is different from N. hakani in having a mandibular palp second article with 11 long setae (vs 6), third article with 19 D-setae (vs 15 D-setae), 5 A-setae (vs 2), 4 groups of B-setae (vs 2 groups) and 5 E-setae (vs 4 in N. hakani ). Distal article of maxilliped palp has no setae on outer margin. Gnathopod I and II palmar spines are shorter than nail (vs as long as or longer than nail in N. hakani ); gnathopod I with 2 small supporting spines on palmar corner (vs 3); gnathopod II with 1 small supporting spine on palmar corner (vs 2 in N. hakani ); all segments of pleopods have long setae; distal article of uropod III exopod is short; telson has no spine on dorsal surface.

The new species can be distinguished from N. kurdistanensis by these differences: robust setae on outer plate of maxilla I have 2 or 3 lateral projections vs 0 or 1 in N. kurdistanensis ; maxilla II has 1 subapical seta but N. kurdistanensis has 2 lateral simple setae instead; in gnathopods I and II robust setae in palmar corner of the propodus have no lateral projections, propodus of gnathopod I is slightly longer than broad, vs trapezoid and broader than long in N. kurdistanensis , with 1 strong palmar robust seta and 2 small spiniform seta, vs 1 strong palmar robust seta, 1 supporting robust seta, and 2 robust setae with lateral projections on outer surface in N. kurdistanensis . Propodus of gnathopod II is as long as broad, vs broader than long in N. kurdistanensis , palmar setae of gnathopods I and II are of moderate size (as long as or slightly longer than the width of the nail), while they are very long in N. kurdistanensis ; uropod III is of moderate size (0.2 of body length) without distal setae on inner ramus, while it is long (almost 0.45 of body length) in N. kurdistanensis and has 3 robust distal setae on inner ramus; telson has 3 robust apical setae (2 in N. kurdistanensis ); anterior margin of epimeral plates II–III are greatly rounded vs almost quadrilateral in N. kurdistanensis .

When compared to N. valachicus , N. keeleri has a maxilla I inner plate of about 2/3 the outer plate length (shorter, about 1/2 the outer plate, in N. valachicus ); palp distal article has 3 long apical setae (vs 4). Pereopods III–IV have long dactyli without spines on inner margin or plumose seta on outer margin (vs 4–5 spines along inner margin, and 1 plumose seta at outer margin in N. valachicus ). Pereopods V–VII are long (vs short and strong in N. valachicus ), with long dactylus having no spines on inner margin nor plumose seta on outer margin (vs 3–5 spines along inner margin, and 1–3 plumose setae at outer margin in N. valachicus ). Postero-distal corner of epimeral plates I–III is slightly acuminated (vs sharply acuminated in N. valachicus ). Distal article of uropod III exopod is short (reaching 1/3 of first segment in N. valachicus ). Telson has no spine on dorsal surface.

Niphargus tauri Schellenberg, 1933 , described from Turkey ( Karaman 1973, 2012), has a much longer distal article in exopod of uropod III, not acuminated postero-distal corner of epimeral plates I–III (slightly acuminated in N. keeleri ), 4 apical spines and 1 lateral spine on telson (vs 3 apical spines and no lateral spine in N. keeleri ), 5 apical setae on distal palp of maxilla I (vs 3 in N. keeleri ), 3 single B-setae on third article of mandibular palp (vs 4 rows of double B-setae in N. keeleri ), and lateral simple setae on inner plate of maxilla II (no setae on N. keeleri ).

Niphargus nadarini Alouf 1972 , reported in Syria and Iraq ( Karaman 2012), has a longer distal article of uropod III exopod and some long single plumose setae on the inner margin of its first article, 21 D-setae on mandible third article (19 in N. keeleri ), and a notacuminated postero-distal corner of epimeral plates I–III (vs slightly acuminated in N. keeleri ).

These comparisons, indicating distinct differences between close species of the region, shows that the newly described species N. keeleri can be quite easily distinguished from all other species, hence supporting our suggestion that it can be regarded as a good species.