Kenji Torigoe

Four species of the genus Stephonyx (Crustacea: Amphipoda: Uristidae) from Japan, with description of a new species

Four species including one new species of the genus Stephonyx are described from Japan: Stephonyx perexcavatus sp. nov., Stephonyx biscayensis (Chevreux, 1908), Stephonyx laqueus (Barnard, 1967) and Stephonyx mytilus (Barnard and Ingram, 1990). Stephonyx perexcavatus sp. nov. is distinguished from the congeners by the combination of the following features: dorsal margin of body smooth, posteroventral corner of epimeral plate 1 not pointed, lateral cephalic lobe rounded, article 1 of mandibular palp shorter than 0.5 times article 2, length of carpus of gnathopod 1 longer than 0.75 times propodus, and palm of gnathopod 2 deeply concave. This is the first record of S. biscayensis and S. mytilus from Japan. A key to the species of Stephonyx is provided.

A new genus and species of the family Mantridae (Copepoda: Cyclopoida) infesting the bivalve Pseudochama retroversa from the Seto Inland Sea, western Japan

Chamicola nagasawai n. gen., n. sp., belonging to the bivalve-infesting cyclopoid family Mantridae, is described from the Seto Inland Sea, western Japan. This is the first recorded occurrence in the Pacific Ocean of the family, which previously accommodated only two genera, Mantra and Nearchinotodelphys. The parasite was found in the mantle cavity of Pseudochama retroversa (Lischke) (Family Chamidae), but did not infect Chama japonica (Lamarck). The prevalence and intensity of C. nagasawai in P. retroversa ranged from 11.3 to 25.0%, and from 1.0 to 2.6, respectively. Considering the host affinity and distribution of ancestral and derived character states, the new genus seems to be more closely related to Mantra than to Nearchinotodelphys.

日本産ケンミジンコ科(甲殻亜門: カイアシ亜綱: ケンミジンコ目)の属の同定法

Two methods are introduced for identifying Japanese freshwater copepods of the family Cyclopidae. The following 14 features, which are all visible without or with minimal dissection, prove to be useful for generic-level identification: (1) segment number of antenna 1, (2) relative length of antenna 1, (3) segment number of exopodites of legs 2 and 3, (4) segment number of exopodite of leg 4, (5) width of coupler of leg 4, (6) segment number of leg 5, (7) number of setae on terminal segment of leg 5, (8) relative lengths of terminal segment of leg 5 and its inner seta, (9) precise location of this inner seta on the segment, (10) relative lengths of inner and outer setae on terminal segment of leg 5, (11) condition of spinule row on outer margin of caudal ramus, (12) condition of dorsal spinule row or setal row on caudal ramus, (13) condition of dorsal chitinous ridge on caudal ramus, and (14) relative length of caudal ramus. Based on these characters, two kinds of key to the genera of Cyclopidae in Japan are provided, a dichotomous branching key and a matrix key. The manner of use of these keys for identification is explained, and the utility of cyclopoids in school education is discussed.

食卓で学ぶ甲殻類のからだのつくり : エビ・カニ・シャコ類の教材化に関する研究

External morphologies of three major edible crustaceans, prawns, crabs, and squillas, are described and compared. Additionally, an example of summary of observation results is shown. The possible availability of crustaceans in education is discussed.