Eoniphargus, (UENO, 1955)

Tomikawa, Ko, Kobayashi, Norio, Morino, Hiroshi & Mawatari, Shunsuke F., 2007, New gammaroid family, genera and species from subterranean waters of Japan, and their phylogenetic relationships (Crustacea: Amphipoda), Zoological Journal of the Linnean Society 149 (4), pp. 643-670 : 646-647

EONIPHARGUS ( UÉNO, 1955)

Neoniphargus (Eoniphargus) Uéno, 1955: 148 .

Eoniphargus: Straškraba, 1964: 136 , 138; Straškraba, 1967: 127; Bousfield, 1977: 301; Barnard & Barnard, 1983: 581–582.

Diagnosis: Eyes absent; dorsal margin of urosomite 3 lacking robust setae; inner plate of maxilla 2 with facial setae in oblique row; carpus of gnathopods 1 and 2 not lobate; propodus of gnathopods 1 and 2 elongate; peduncles of pleopods with few setae; epimeral plates lacking ventromarginal setae; uropod 3 parviramous (length of inner ramus up to 0.3 × length of outer ramus).

Type species: Neoniphargus (Eoniphargus) kojimai Uéno, 1955 , original designation.

Remarks: As mentioned in the remarks on Mesogammaridae , Eoniphargus is morphologically similar to Indoniphargus in having the absence of eyes, the pedunculate coxal gills and the small inner ramus of the uropod 3. However, Eoniphargus differs from Indoniphargus by the following characters ( Indoniphargus in parentheses): the dorsal margin of the urosomite 3 is bare (with robust setae); the outer plate of the maxilla 1 bears 10 or 11 robust serrate setae (8 setae); the inner plate of the maxilla 2 bears facial setae in a oblique row (lacking); the carpus of the gnathopods is not lobate (lobate); and the propodus of the gnathopods is elongate (mittenform).

KEY TO THE GENERA OF MESOGAMMARIDAE AND INDONIPHARGUS 1 Propodus of gnathopods stout, coxal gills unstalked ......................................................................................................... 2

– Propodus of gnathopods feeble, coxal gills pedunculate .................................................................................................... 3

2 Pleonites 1–3 strongly toothed posterodorsally ......................................................................................... Mesogammarus

– Pleonites 1–3 untoothed dorsally ........................................................................................................ Paramesogammarus

3 Uropod 3 magniramous...................................................................................................................................... Octopupilla

– Uropod 3 parviramous ......................................................................................................................................................... 4

4 Inner plate of maxilla 2 with facial setae in oblique row, propodus of gnathopods 1 and 2 elongate....... Eoniphargus

– Inner plate of maxilla 2 without facial setae in oblique row, propodus of gnathopods 1 and 2 mittenform .................. ........................................................................................................................................................................ Indoniphargus

Two species are included in this genus at present: Eoniphargus kojimai ( Uéno, 1955) and E. glandulatus Stock & Jo, 1990 . They inhabit subterranean waters in Japan and Korea.