NORTH AMERICAN MILLIPEDS OF THE GENUS EURYURUS (POLYDESMIDA: PLATYRHACIDAE)

A considerable area of the two American continents, extending from the Amazon Basin north as far as the Great Lakes, is occupied by representatives of a relatively small but distinctive group of polydesmoid millipeds characterized, in part, by the unusually broad and distally truncated epiproct. Previous authorities have recognized this assemblage either as a distinct family Euryuridae, as a subfamily within the Platyrhacidae, or merely as an innominate group of genera in the latter family. The structural character traditionally relied upon to separate euryurid and platyrhacid species, the configuration of the ozopores and their surrounding peritremata, is both variable and somewhat subjective. After examining numerous forms in both groups, I have concluded that it is neither constant or significant enough to distinguish categories at the family level. In addition, there are no important differences in other aspects of external sculpture or in gonopod form, and I am therefore now inclined to follow the arrangement of Pocock (1909) and of Brolemann (1916) in regard ing the euryurid millipeds as comprising a subfamily equivalent to the somewhat larger and apparently derivative group Platyrhacinae. In 1954, I published a provisional classification of the euryurids in which several subfamilies were recognized. My arrangement was subsequently questioned, in some of its parts, by my colleague C. A. W. Jeekel and obviously some refinements are in order. With the present reduction of the group to subfamily status, the two previous subfamilies Euryurinae and Amplininae now assume tribal rank, as Euryurini for the genera of North America, and Amplinini for various taxa extending from Mexico to Peru and Brazil. The status of the somewhat divergent genus Aphelidesmus has not been settled. Jeekel has, quite correctly, divested my sub family Aphelidesminae of the genera Varyomus and Prota