Niphargus absconditus, Stoch & Knüsel & Zakšek & Alther & Salussolia & Altermatt & Fišer & Flot, 2024

Niphargus absconditus View in CoL n. sp. Fišer, Stoch &

Salussolia

h t t p s:/ / z o o b a n k.o r g/N o m e n c l a t u r a l Acts/ 3167505F-7C27-441F-8709-5A23A56EE867

Type series. Vadu Crişului Cave , Apuseni Mountains (Western Carpathians), Bihor County, Romania, 29/09/2011, leg. I. Meleg, 2 males, 3 females. Holotype (male) and paratypes (1 male, 3 females) deposited in the amphipod collections of the University of Ljubliana, code n. NA797 (holotype), NA798 (male paratype) and NA794-NA796 (female paratypes).

Type locality. Vadu Crişului cave ( WGS84 coordinates: longitude: 22.511003° E, latitude 46.962406° N), Romania GoogleMaps .

Derivatio nominis. The adjective ‘ absconditus ’ in Latin means ‘hidden’, ‘cryptic’.

Description and remarks. Being the morphological characters very similar to those of N. bihorensis , a complete description is not given, focusing on few relevant aspects.

Holotype male, body length 6.0 mm. Antenna I ( fig. 7a View FIGURE 7 ), flagellum of 20 articles; distal article shorter than in the type of N. bihorensis . Antenna II ( fig. 7b View FIGURE 7 ), flagellum of 7 articles.Mouthparts as in N.bihorensis .Maxilla 1 ( fig. 7c View FIGURE 7 ) with palp articles ratio 1:2, distal article bearing 5 apical setae. Gnathopod I ( fig. 7d View FIGURE 7 ) as in N. bihorensis .

Gnathopod ii with elongated basipodite. 3 times longer than wide. Pereopods III ( fig. 8a View FIGURE 8 ), IV ( fig. 8b View FIGURE 8 ) and V ( fig. 8c View FIGURE 8 ) as in N. bihorensis . Pereopod VI ( fig. 8d View FIGURE 8 ) and VII ( fig. 8e View FIGURE 8 ) slender than in N. bihorensis ; basipodites with straight posterior margins, without distal lobes, approximately 2 times longer than wide.

Pleopods as in N. bihorensis . Uropods 1 and 2 ( fig. 7f View FIGURE 7 ) with rami more elongated than in the type of N. bihorensis ; distal spines longer and more gracile, but in equal numbers than in the previous species. Endopod of uropod 3 more elongated than in the type of N. bihorensis , about 2 times longer than wide. Epimeral plates ( fig. 7g View FIGURE 7 ) and telson as in N. bihorensis .

Apart from the slightly more elongated pereopods and uropodal rami, no sound morphological differences could be found between the population from Vadu Crişului Cave and the population from Meziad Cave (typical N. bihorensis ); thus, the new species can be considered cryptic with regards to N. bihorensis . All the morphological traits studied showed a considerable degree of overlap between the two populations ( table 1). The most promising characters appeared to be the dorsal spine on the telson lobes, found only in males. Most males from the Meziad Cave had this spine, but only one male from the Vadu Crişului Cave had it; however, the N. bihorensis holotype in Schellenber’s collection lacked this spine. Even this trait, polymorphic in both populations, cannot be used for a diagnosis. It is possible that other diagnostic traits or diagnostic combinations of traits were overlooked; however, with our current knowledge of morphology, we were unable to discriminate between these two populations.

Up to now, the new species is known only from Vadu Crişului Cave; details of its ecology are reported in Meleg et al. (2013).

Diagnostic molecular characters. The species can be distinguished from N. bihorensis and from all other niphargid species on the basis of COI and 28S DNA sequences (supplementary table S1). COI: KF218667-679; 28S: KF218731-732 (GenBank Accession Numbers).

Molecular diagnosis. ‘G’ at site 292, ‘G’ at site 325, ‘G’ at site 502; support 100%.