MYSIDACEA FROM THE CENTRAL AND WESTERN PACIFIC -I. GENUS PSEUDOMMA (TRIBE ERYTHROPINI)-

Abstract

In Ocean Research Institute, University of Tokyo, there are collections of Mysidacea being composed of over 120 species including a number of new and rare species. These collections were mostly obtained by two methods, using a large-sized conical plankton net with its mouth diameter of 160 cm (ORI-net) and a net with a runner in its lower part (bottom-net). I have the intention of publishing in series the reports on the taxonomy and distribution of these mysids. As the first paper, 18 species belonging to genus Pseud omma, 11 of which proved to be new, are discussed. Since genus Pseudomma was established in 1870 by G. O. Sars, 24 species have been known throughout the world oceans and seas. (Recently Pseudomma oculospinum W. Tattersall was transferred to Scolamblyops by Murano.) Five species already known, P. calloplura, P. multispina, P. matsuei, P. izuensis and P. japonicum, from the adjacent seas of Japan are represented as parts of the present collections. However, P. sp. which was reported in 1964 by Ii from Sagami Bay has the peculiarly hispidulous character of the integument of the appendages and still remains an indefinite species. Generally, the genus Pseud omma seems to live on or close to the sea-floor, but not in the mid-layers of the sea, so that 14 species were caught by the bottom-net, 3 by the plankton net attached to the mouth of a beam trawl, 3 by the ORI-net which accidentally touched the sea-floor, and 2 from the stomachs of benthic fishes. (Among these, 4 species were taken by two methods.) The sampling date, time, position and depth are listed in appendix-tables. The type specimens in the collections are stored in Ocean Research Institute, University of Tokyo.