A new species of calanoid copepod Pontella rostraticauda (family Pontellidae) is described based on specimens collected in surface waters of the Inland Sea of Japan. Due to its neustonic character, this species may have been overlooked by previous investigators. The gut content analysis revealed that this species feeds on a wide variety of foods, including both zooplankters and phytoplankters, and can be classified as an omnivorous copepod. The new species is closely allied to P. surrecta Wilson and P. alata Scott and is distinguished from them by the shape of the female urosome and the fifth legs of both sexes. Several derived characters shared by the three species and their geographical distributions provide the basis for proposing the Pontella alata species group as a unique radiation within the genus. Species of this lineage tend to occur in coastal waters around those oceanic islands comprising the western rim of the tropical Pacific. The group occurs north to southern Japan and south to the Great Barrier Reef. Until now, only four species of the family Pontellidae have been recorded from the central part of the Inland Sea of Japan (Setonaikai): Calanopia thompsoni Scott, Labidocera rotunda Mori, Pontellopsis tenuicauda (Giesbrecht), and Pontellopsis yamadae Mori (Hirota, 1961, 1964, 1968a, b, 1979; Kado, 1954, 1957; Ohtsuka, unpublished). In contrast to such a low species diversity in the Inland Sea, 21 species of the family Pontellidae have been collected in summer in the Kuroshio Current region, south of Shikoku, Japan (Matsuo and Marumo, 1982). During the course of our investigation on the neuston of the Inland Sea of Japan in the summer of 1985, a new species of the genus Pontella (family Pontellidae) was found. As far as we know, the present species appears to be the first new calanoid copepod from the Inland Sea of Japan. The new species feeds on a variety of organisms, and is apparently omnivorous. The present paper deals with the description of the new species of Pontella, its feeding habits, and its phylogenetic as well as biogeographic relationships. MATERIALS AND METHODS Neuston samples were collected at Station A-1 and Stations B-1 to B-5, respectively, on 21 June and 8, 9 August 1985, in Hiuchi-Nada, the central part of the Inland Sea of Japan (Fig. 1). The Ocean Research Institute (ORI) neuston net with a mesh size of 0.33 mm (Matsuo et al., 1976) was towed for 10 min at a speed of about 2 knots on board T/RV Toyoshio-maru, Hiroshima University. The samples were fixed with 10% neutralized Formalin-sea water immediately after capture. Prosome length was measured for intact specimens collected in August. Gut contents dissected out were examined with a scanning electron microscope (JSM T-20 SEM). Twenty intact specimens of each sex were randomly selected from the samples collected at Stations B-1, B-2, and B-3 to examine the frequency of occurrence of food items in the guts. The gut was removed from the body and immersed in gum-chloral medium on a thin glass slide, dissected, and, after adding a cover slip, examined under a differential interference microscope. Intact food organisms in the guts of the pontellids were measured with an ocular micrometer. We used the criterion of morphological similarity in derived sexual characters (synapomorphies) in both sexes to shed light on the phylogenetic relationships of the new species. Zooplankton sampling outside of the Inland Sea of Japan that yielded new geographic records of species closely related to the new species was based mostly on surface tows with standard conical nets