Niphargus frasassianus, Karaman, Gordan S., Borowsky, Betty & Dattagupta, Sharmishtha, 2010

Karaman, Gordan S., Borowsky, Betty & Dattagupta, Sharmishtha, 2010, Two new species of the genus Niphargus Schiödte, 1849 (Amphipoda, fam. Niphargidae) from the Frasassi cave system in Central Italy, Zootaxa 2439, pp. 35-52 : 44-51

Niphargus frasassianus , n.sp.

( Figs 7–12 )

Material examined. ITALY: “Pozzo dei Cristalli”, in Frasassi cave system (Genga region, central Italy), May 27, 2008, 2 specimens (leg. Dattagupta, S.) — holotype and paratype.

–Tunnel of the sulfide spring (“Sorgente sulfurea del tunnel”), Frasassi cave system [Genga region, central Italy), 14 September, 2009, many specimens [leg. Karaman, G. & Karaman, B.].

– ibid., 15. September, 2009, many specimens [leg. Borowsky, B. & Borowsky, R.].

– “Grotto sulfureo, ramo sulfureo” (Frasassi cave system), 2008 and 2009, 5 specimens (leg. Dattagupta, S.).

Holotype and paratype are deposited in the Museum of Natural History in Verona, Italy.

Diagnosis. Body stout. Epimeral plates 1–3 with slightly rounded ventroposterior corners in males. Gnathopods 1–2 relatively small, only slightly unequal in size and shape, with dactyl reaching posterior margin of segment 6 and provided with a row of long setae along outer margin. Pereopods 3–7 short and stout, their dactyl short, with one spine along inner margin. Segment 2 of pereopods 5–7 less than twice as long as broad, Pleopods with 2 retinacula each. Uropods 1–2 with inner ramus much longer than the outer one. Second segment of uropod 3 in males exceeding half of first segment, in females is much shorter. Telson short, bearing short distal, marginal and facial spines. Outer plate of maxilla 1 with 7 spines; some of these spines with 2 or 3 lateral teeth sitting in the opposite sides of the spine itself.

Description. Male 15 mm, mature (holotype):

Body strong and stout, metasomal segments 1–3 with 3 or 4 dorsoposterior short marginal setae each. Epimeral plates 1–3 with slightly rounded ventroposterior corner; plates 2–3 with 3 or 4 short subventral spines each (fig. 9H). Urosomite 1 on each side with one spine-like seta, urosomite 2 with 2 dorsolateral spines on each side, urosomite 3 smooth (fig. 7G). Urosomite 1 with ventroposterior short spine near the basis of peduncle of uropod 1 (fig. 7G).

Head with short rostrum and short slightly rounded lateral cephalic lobes (fig. 7A), eyes absent.

Antenna 1 reaching one third of the body-length; peduncular segments 1–3 progressively shorter; peduncular segment 3 slightly exceeding half of peduncular segment 2 (fig. 7B), all sparsely setose; main flagellum consisting of 19 articles (most of them with one short aesthetasc each); accessory flagellum short, 2- segmented (fig. 7D).

Antenna 2: peduncular segment 5 shorter than 4, each with bunches of longer setae (fig. 7C); flagellum longer than last peduncular segment, consisting of 11 articles; antennal gland cone short (fig. 7C).

Coxae 1–4 short, coxae 1–3 nearly as long as broad (figs 8B–D, 9A), coxa 4 slightly broader than long (high), all with short marginal setae (fig. 9C). Coxa 1 with slightly rounded ventroanterior corner. (fig. 8B). Coxae 5–7 short (fig. 10B, D, F).

Labrum entire, similar to that of N. montanarius . Labium without inner lobes, similar to that of N. montanarius . Maxilla 1: inner plate with 2 setae, outer plate with 7 spines: inner spine with 3–5 lateral strong setae, 6 spines with 2 lateral strong teeth sitting at opposite sides of spines (fig. 7E, F); palp 2-segmented, short, with 6 long distal setae slightly shorter than last segment (fig. 7E).

Maxilla 2: both plates with numerous marginal setae only (fig. 8A).

Maxilliped: inner plate short, with 3 distal spines intermixed with single setae (fig. 10A); outer plate not exceeding half of posterior margin of palp segment 2, with row of marginal spines; palp segment 3 at outer margin with one medial and one distal bunch of setae (fig. 10A); palp segment 4 with nail shorter than pedestal.

Left mandible: incisor with 5 teeth and 9 rakers, lacinia mobilis with 4 teeth (fig. 11B). Right mandible: incisor with 4 teeth and 8 rakers, lacinia mobilis pluridentate (fig. 11A).

Palp of both mandibles 3-segmented: first segment smooth; second segment with 13–15 setae; palp segment 3 short, almost a long as palp segment 2, bearing at posterior margin 26 D-setae and 7 long distal Esetae (fig. 11C); there are 5 single B-setae on the inner face (fig. 11C), and one group of 7 A-setae on the outer face (fig. 11D).

Gnathopods 1–2 relatively small, stout, their segment 6 is not larger than corresponding coxae (fig. 8B, D). Gnathopod 1 slightly smaller than gnathopod 2, segments 3–4 of both gnathopods along posterior margin with one group of setae (fig. 8B, D), segment 5 is slightly shorter than segment 6.

Gnathopod 1: segment 6 slightly longer than broad, with almost parallel lateral margins, and along posterior margin with 6 groups of setae (fig. 8C). Palm convex, oblique almost to half of segment 6 length, defined on outer face by one strong corner spine accompanied laterally by 3 slender toothed spines and 5 long setae on the face (fig. 8C), one short subcorner spine on the inner face (fig. 8C); dactyl reaching posterior margin of segment 6, strong, bearing row of 6 long marginal setae along outer margin (fig. 8C).

Gnathopod 2: segment 6 slightly longer than broad, trapezoidal shape, with 8 groups of setae along posterior margin (fig. 8E), palm slightly convex, oblique to nearly 2/5 of segment 6 length, defined on outer face by one strong corner spine accompanied laterally by 3 slender toothed spines and 5 long setae (fig. 8E), on inner face by one short subcorner spine (fig. 8F); dactyl reaching posterior margin of segment 6, with 8 strong setae along outer margin (fig. 8E).

Pereopods 3–4 nearly equal, stout, with strong articles (fig. 9A, C); dactyls short and stout, with one spine at inner margin, nail nearly as long as pedestal (fig. 9B, D).

Pereopods 5–7 short and stout, progressively longer towards pereopod 7, segment 2 less than twice as long as broad, with straight or slightly concave posterior margin bearing very short marginal setae (fig. 10B, D, F), ventroanterior lobe not developed, ventroposterior area enlarged, but without distinct lobe; segments 3–6 short and broad, segments 4–6 with bunches of strong spines and single setae on both margins; dactyl short and stout, with one spine on inner margin and one median seta on outer margin. Nail of dactyl on pereopod 5 nearly as long as pedestal (fig. 10C), those of pereopods 6–7 shorter than pedestal (fig. 10E, G).

Pleopods 1–3 with 2 retinacula each. Peduncle of pleopod 1 with 3 anterior marginal setae (fig. 9E); peduncle of pleopod 2 with one anterior marginal seta (fig. 9F); peduncle of pleopod 3 with 2 short posterior marginal setae (fig. 9G).

Uropod 1: peduncle with dorsoexternal row of spines and dorsointernal row of setae (except distal spine) (fig. 7G). Outer ramus reaching nearly 3/5 of inner ramus, both with lateral and distal spines, inner ramus with 2 bunches of long setae also (fig. 7G).

Uropod 2: outer ramus slightly shorter than inner one, both rami with lateral and distal spines (fig. 7G). Uropod 3 elongated, inner ramus short, scale-like, with 2 lateral and distal short spines; outer ramus long, 2-segmented, first segment with bunches of short spines and single setae along both margins; second segment exceeding half of first segment, bearing short setae at both margins (fig. 11E).

Telson slightly broader than long, with gaping lobes, each lobe with 4 distal spines (fig. 7H); several single spines appear at both margins and face of each lobe; a pair of short plumose setae appears near the middle of each lobe.

Coxal gills not reaching distal tip of corresponding segment 2 (fig. 9A).

Female 10.0 mm, mature (paratype, with setose oostegites): Antenna 1 reaching one third of the bodylength; main flagellum consisting of 18 articles; flagellum of antenna 2 is with 7 articles. Urosomal segment 1 with one dorsolateral seta on each side (fig. 12 I); urosomite 2 with 2 spines on each dorsolateral side (fig. 12I). Coxa 1 broader than long, coxae 2–3 slightly longer than broad, coxa 4 nearly as long as broad (fig. 12A–D).

Mouthparts as in male. Outer plate of maxilla 1 as in male, 6 spines provided with 2 opposite lateral strong teeth (fig. 11F). Inner plate of maxilliped with 3 distal spines.

Mandibular palp segment 2 with 11 setae; palp segment 3 with 23 D-setae and 6 long distal E-setae; on outer face on group of 5 A-setae, on inner face 5 single B-setae.

Gnathopods 1–2 have slightly different size, their segment 6 trapezoid, slightly longer than broad, with palm oblique slightly less than half of posterior margin of segment 6, almost straight. Gnathopod 1: posterior margin of segment 6 with 5 groups of setae (fig. 11G), 5 facial setae are present near corner spine. Gnathopod 2: posterior margin of segment 6 with 6 groups of setae, 4 setae present near corner spine (fig. 11H).

Pereopods as in males, but segment 2 of pereopods 5–7 slightly shorter, with poorly developed ventroposterior lobe (fig. 12E–G).

Epimeral plates 1–2 broadly angular, with convex posterior margin (fig. 12H) and subventral spines, epimeral plate 3 with produced almost subrounded ventroposterior corner (fig. 12H). Oostegites broad, setose. Uropod 1: peduncle with dorsoexternal row of spines and dorsointernal row of setae (except distal spine), inner ramus only slightly longer than outer one, both with lateral and distal strong spines (fig. 12I).

Uropod 2: inner ramus slightly longer than outer one, both rami with lateral and distal spines (fig. 12I). Uropod 3 short, first segment of outer ramus with bunches of spines along both margins, and with single plumose setae along inner margin (fig. 11I); second segment of outer ramus short, with marginal setae. Telson slightly broader than long, lobes slightly gaping, each with 3 distal single marginal and facial spines (fig. 12J).

Variability. The stable characters are the specific shape of the spines on the outer plate of maxilla 1, the presence of one spine along the inner margin of the dactyl of pereopods 3–7, and a short segment 2 of pereopods 5–7 with a marked enlarged ventroposterior corner (not distinct lobe).

Etymology. This species is based on the name of the Frasassi cave system in central Italy, where it is found.

Remarks. Niphargus frasassianus differs from all other known Niphargus species of Italy by the shape of the spines on the outer plate of maxilla 1: some spines have 2 or 3 lateral teeth on the opposite side of the spine, a modification that may permit specialized feeding, especially sediment straining.

A robust body with short strong gnathopods and pereopods is present in some other species in the Adriatic region, including Niphargus spinulifemur S. Kar., 1954 known from Zazid (= Sassetto) in Istria, Croatia. But this species differs significantly from N. frasassianus in its strongly pointed epimeral plates, its substantially greater number of setae on the gnathopods, the different shape of spines on maxilla 1, etc.

N. frasassianus may be close to the Niphargus puteanus complex of species which also have strong bodies and pereopods (some with and some without more numerous spines on pereopod dactyls and pointed to subangular epimeral plates), but it differs from all of them in the shape of maxilla 1.

Figures

FIGURE 7. Niphargus frasassianus, n. sp., Pozzo dei Cristalli, male 15 mm (holotype): A = head; B = antenna 1; C = antenna 2; D = accessory flagellum; E, F = maxilla 1; G = urosome with uropods 1 – 2; H = telson. Scale bars: 1 = 0.17 mm (D); 2 = 0.25 mm (E); 3 = 0.25 mm (H); 4 = 0.25 mm (A, C); 5 = 1.0 mm (B); 6 = 1.0 mm (G).

FIGURE 8. Niphargus frasassianus, n. sp., Pozzo dei Cristalli, male 15 mm (holotype): A = maxilla 2; B, C = gnathopod 1; D – F = gnathopod 2. Scale bars: 1 = 0.25 mm (A); 2 = 0.5 mm (C, E); 3 = 1.0 mm (B, D).

FIGURE 9. Niphargus frasassianus, n. sp., Pozzo dei Cristalli, male 15 mm (holotype): A, B = pereopod 3; C, D = pereopod 4; E – G = peduncle of pleopods 1 – 3; H = epimeral plates 1 – 3. Scale bars: 1 = 0.5 mm (E – G); 2 = 1.0 mm (H); 3 = 1.0 mm (A, C).

FIGURE 10. Niphargus frasassianus, n. sp., Pozzo dei Cristalli, male 15 mm (holotype): A = maxilliped; B, C = pereopod 5; D, E = pereopod 6; F, G = pereopod 7. Scale bars: 1 = 0.5 mm (A); 2 = 1.0 mm (B, D, F).

FIGURE 11. Niphargus frasassianus, n. sp., Pozzo dei Cristalli, male 15 mm (holotype): A = right mandible; B = left mandible; C = mandibular palp, inner face; D = tip of mandibular palp, outer face; E = uropod 3. Female 10 mm (paratype): F = maxilla 1, tip of outer plate; G = propodus and dactylus of gnathopod 1; H = propodus and dactylus of gnathopod 2; I = uropod 3.

FIGURE 12. Niphargus frasassianus, n. sp., Pozzo dei Cristalli, female 10 mm (paratype): A – D = coxae 1 – 4; E – G = segment 2 of pereopods 5 – 7; H = epimeral plates 1 – 3; I = urosome with uropods 1 – 2; J = telson. Scale bars: 1 = 0.25 mm (J); 2 = 0.5 mm (I); 3 = 0.5 mm (A – D); 4 = 0.5 mm (H); 5 = 1.0 mm (E – G).