Abstract
Ostrinia ovalipennis has been recorded only in Shigakogen, a highland area in Honshu. Here, we report the occurrence of the species in Hokkaido. Since Ostrinia latipennis, a close relative of O. ovalipennis, is distributed widely in northeastern Japan, these two species occur sympatrically at some localities. The two species can be diagnosed based on the wing morphology. Another diagnostic character useful for distinguishing the Shigakogen population of O. ovalipennis from O. latipennis, i.e., the sacculus length (SL) of male genitalia, could not distinguish some individuals of the Hokkaido population of O. ovalipennis from O. latipennis. To revise the species diagnosis of the two species in terms of male morphometric traits, and to compare the degree of geographic differentiation in morphology between the two species, we analyzed 10 morphological traits. A linear discriminant analysis showed that O. ovalipennis could be distinguished from O. latipennis by a combination of two traits, SL and mid femur length. Morphological differentiation was greater between the Shigakogen and Hokkaido populations of O. ovalipennis than between the same local populations of O. latipennis. We suggest that the difference in the degree of geographic differentiation between the two species has been caused by the difference in their distribution patterns.
