A New Genus Of Ghost Shrimp From Japan (Crustacea : Decapoda : Callianassidae)

—A new genus, Nihonotrypaea, is recognized for three species from Japan formerly assigned to Callianassa sensu lato: TV. japonica (Ortmann, 1891), the type species; Â . harmandi (Bouvier, 1901); and TV. petalura (Stimpson, 1860). One of us (A.T.) has carried out studies on the biology and development of the shallow water species, Callianassa japonica Ortmann, 1891, in an estuarine system on western Kyushu Island, Japan since 1989 (Tamaki et al. 1996, Tamaki et al. 1997). These studies revealed consistent differences in biology, development, habitat, and morphology in populations from different areas within the estuary, which extends from Ariake Sound through Tachibana Bay to the East China Sea (Tamaki et al. 1997: fig. 1). One of us (R.B.M.) examined samples from different localities within the study area and found that not only were there two species involved, but also that morphological characters warranted their separation into a new genus of Callianassinae. That two similar species occurred in Japan had been recognized by De Man (1928), who identified them as C japonica and C. harmandi Bouvier, 1901, and clearly figured their diagnostic features; De Man's material all came from Bingo, Japan. De Man's findings generally have been ignored by subsequent students of the group. Sakai (1969) synonymized C. harmandi with C. japonica and recognized C. petalura Stimpson, 1860 as a distinct species. As numerous studies on the biology of these species are in preparation by Tamaki and his colleagues and students, we decided to prepare this preliminary account to correct the specific names and make the generic name available. A more detailed account of the new genus and all three species assigned to it is in preparation by us. Family Callianassidae Dana, 1854 Subfamily Callianassinae Dana, 1854 Nihonotrypaea, new genus Diagnosis. —Carapace lacking rostral spine, minute median spinule present or absent. Cornea dorsal, subterminal, discshaped (Fig. la, b). Antennular and antennal peduncles similar. Third maxilliped (Fig. Ic, d) lacking exopod, ischium-mems suboperculiform, merus projecting beyond articulation with carpus; latter, propodus and dactylus slender. Chelipeds unequal, both with meral hook. First pleopod slender, uniramous in both sexes (Fig. le,f). Second pleopod absent in male, slender, biramous in female (Fig. Ig). Third to fifth pleopods with stubby, projecting appendices internae (Fig. Ih) in both sexes. Type species. —Callianassa japonica Ortmann, 1891, by present designation. Included species. —Nihonotrypaea japonica (Ortmann, 1891), new combination; TV. petalura (Stimpson, 1860), new combination; and TV. harmandi (Bouvier, 1901), new combination. Etymology. —The generic name is formed by combining the Japanese name 890 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Fig. 1. Nihonotrypaea harmandi (Bouvier, 1901). a. Front and eyes; c. Third maxilliped, outer surface; d. Third maxilliped, inner surface; e. First pleopod of female; / , First pleopod of male; g. Second pleopod of female; h, Appendix interna of third pleopod of male {a;e,f, h, from De Man 1928: pi. 5, fig. 10, as Callianassa (Trypaea) japonica). b, N. japonica (Ortmann, 1891), from De Man 1928:pl. 3, fig. 6, as Callianassa (Trypaea) harmandi); c, d, g, female from Tomioka (National Museum of Natural History, Smithsonian Institution, Washington, D.C.). Scale = 1 mm, c, d; 0.5 mm, g. for Japan, Nihon, with the generic name Trypaea. The gender is feminine. Remarks. —With the addition of Nihonotrypaea, nine genera are now recognized in the callianassid subfamily Callianassinae. Nihonotrypaea can be distinguished from those with projecting appendices intemae on pleopods 3-5 as follows: from Biffarius Manning & Felder, 1991 in that the size of adults is larger, the antennal and antennular peduncles are similar in size and shape, and the third maxilliped is much narrower; from Calliapagurops de Saint Laurent, 1973 by its sub terminal corneas; from Notiax Manning & Felder, 1991 in lacking a strong median spine on the carapace and in having the merus of the third maxilliped projecting beyond its articulation with the carpus; from Poti Rodrigues & Manning, 1992, by the presence of a complete linea thalassinica on the carapace; from Trypaea Dana, 1852 in having a much smaller and shorter antennular peduncle. In the three other genera in the subfamily {Callianassa Leach, 1814; Gilvossius Manning & Felder, 1992; and Neotrypaea Manning & Felder, 1991), the appendices internae of pleopods 3-5 are embedded in the margin of the endopod. That feature alone distinguishes members of these three genera from Nihonotrypaea, in which the appendices intemae are projecting from the margin of the endopod. One of the three species assigned to Mhonotrypaea, N. petalura, lives among boulders in the intertidal zone of oceanVOLUME 111, NUMBER • 891 front beaches. The two other species, N. japonica and Â . harmandi, live on protected flats in estuaries. The range of N. petalura is identical to that of A' . harmandi. Although De Man (1928) was correct in recognizing C. japonica and C. harmandi as distinct species, he assigned the wrong name to each of them, for he did not have access to their types and the original accounts were quite short. The two species can be distinguished by the size of their cornea alone, as shown by De Man (1928). In Â . harmandi (Fig. la) the cornea is relatively large, at least half the width of the stalk, whereas in Â . japonica (Fig. \b) the cornea is much smaller, one-third to onefifth the width of the stalk. In A' . harmandi, the front often is ornamented with a minute spinule, which is lacking in N. japonica. All members of the genus are relatively small, total lengths up to about 65 mm. The two species also differ in aspects of biology, habitat, and their parasites (Manning & Tamaki, in preparation). The original citations of the two species