PROC. BIOL. SOC. WASH. 103(3), 1990, pp. 624-632 THE JAPANESE AMPHIPOD GENUS EONIPHARGUS, REDISCOVERED IN A SOUTH KOREAN CAVE Jan H. Stock and Young Won Jo Abstract.— Eoniphargus, a monotypic genus, known only from the Tokyo area, Japan, has been rediscovered in cave waters of South Korea. The Korean animals are a new species, E. glandulatus, which bridges to a certain extent the gap between Eoniphargus and the Indian genus Indoniphargus. Their mor-phology indicates that these genera are more closely related to the Gammaridae than to the Crangonyctidae. Among a number of stygobiont amphi-pods collected by the junior author in cave waters of South Korea, a representative of a new species was discovered belonging to a small group of two monotypic genera, Eoniphargus Ueno, 1955 {Eoniphargus was originally described as a subgenus of Neoni-phargus, but was elevated to generic rank by Straskraba 1964), and Indoniphargus Straskraba, 1967. The former is known from a single locality near Tokyo (Japan), where-as the latter is known from the states of West Bengal and Orissa (India). The Korean tax-on bridges to a certain extent the gap be-tween Eoniphargus and Indoniphargus: of the ten discriminating characters, three agree better with Indoniphargus, whereas seven correspond with Eoniphargus (Table 1). The resemblance to Eoniphargus bears amongst others on the shape of the gnathopods 1 and 2, and the armature of the inner and outer lobes of maxilla 1 , both considered of prime importance in amphipod taxonomy. The resemblance to Indoniphargus bears on "weak" characters (urosome spination, number of segments in the accessory fla-gellum, absence of calceoli), known to be variable, sometimes even at infraspecific level. Therefore, the Korean form has been attributed to Eoniphargus rather than to In-doniphargus. Eoniphargus and Indoniphargus have often been thought related to the crango-nyctids or crangonyctoids (e.g., Bousfield 1977:table VI, Bousfield 1982:262, Stras-kraba 1964:table I, Straskraba 1967). Bar-nard & Barnard (1 983) classify Eoniphargus near the gammarids, but Indoniphargus near the melitids. Clearly enough, and contrary to what the generic names suggest, these genera are not closely related to the Ni-phargidae. In our opinion, several points in their morphology prohibit inclusion in the crangonyctids s.l. (= superfamily Crango-nyctoidea Bousfield), e.g., the asymmetrical palps of left and right maxillae, the occur-rence of spines on the urosome, the 'eulim-nogammarid' shape of the gnathopods of Eoniphargus, the absence of sternal gills, the absence of a coxal gill on pereiopod 7, the absence of a double row of distally-notched spine teeth on the palm of the two gnatho-pods, the rather elongate third uropod, the occasional presence of calceoli described as shoe-shaped by Ueno (1955:fig. 1) on an-tenna 2 of the male. None of these char-acters alone is sufficient proof of a non-cran-gonyctid relationship, but in combination they probably show that Eoniphargus forms a subgroup of the gammarids (or gamma-roids, if one believes in superfamilies in this group). Eoniphargus glandulatus, new species Material. — 1 9 (holotype), 1 $ (allotype), 4 paratypes. South Korea, Ondal-gul (gul = cave), Prov. Choongbuk, Danyang-gun,
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