A newly recorded species of Philostephanus Distant, 1909 from Korea, P. ulmi (Kerzhner, 1979), is reported with brief taxonomic notes on the Korean Philostephanus species. Morphological keys of the Korean Philostephanus species are provided with the photos of adults and female genitalia for each species.

The small brown planthopper (SBPH), Laodelphax striatelleus (Fallén), is a insect vector of Rice stripe virus (RSV) in temperate countries such as Korea, Japan, China, and Taiwan. As SBPH is able to overwinter successfully in these areas, RSV disease in subsequent rice fields has been believed to be endemic. In Korea, however, the RSV disease outbreaks have been observed mainly but not continuously at some western regions since 2001, caused a severe damage to the rice production. Although many efforts are underway to explain the outbreak phenomenon, the exact related factors are not known yet. In the meantime of the study on SBPH population dynamics in 2009, we catched unusually large numbers of SBPH adults by aerial net traps, maximally over 900, in early June at western coastal counties such as Taean, Seocheon, Buan, Sinan, and Jindo in Korea. Age distribution changes of SBPH in winter and post-winter seasons at some selected fields shows that the adults might be not related to overwintering population. The adults of overwintering population emerged from early April. Newly hatched nymphs of first generation were found from mid-May. In late May, just before the unusual catch of adults, the developmental stages of SBPH were mostly below 5th instars. This means that the big adult populations would be results of mass migration of SBPH abroad. We present also spacial distribution and host relationship of overwintering population as well as viruliferous rate changes of immigratory population.

The genus Philostephanus Distant 1909 belongs to the family Miridae, including 23 species from the eastern Palearctic and the Oriental regions. They are characterized with a relatively large body, brown or fuscous coloration, rather symmetrical parameres of male genitalia, and unique structures of female genitalia. Especially, the respective structures of female genitalia exhibit distinct interspecific variation, which is uncommon in other genera of Miridae, so they are used as key characters in identification and phylogenetic study. Most of members are known to inhabit deciduous trees, and their feeding habits are considered predominantly predaceous although some species are known to use some deciduous trees as their breeding hosts (Yasunaga & Schwartz, 2007). Presently, two species are reported in the Korean fauna (Kwon et al., 2001). During our study, we found one newly recorded Philostephanus species from Korea, P. ulmi (Kerzhner 1979), which is distinguished from other Korean congeners by speckled hemelytra with pale portions. In this study, we provide taxonomic information on P. ulmi and review briefly the Korean Philostephanus species with morphological keys and photos of specimens.

Two species of Miridae, Pachylygus nigrescens (Kerzhner 1977) and Deraeocoris yasunagai Nakatani 1995, are reported for the first time from Korea. The brief information on them is presented with the photos of specimens.

Since Miyamoto & Lee (1966) first recorded three species of Miridae, many species including new species are added to the fauna of Korea by several Korean and foreign taxonomists (Josifov, 1992; Josifov & Kerzhner, 1972; Lee & Kwon, 1991; Lee et al., 1993; Lee et al., 1994). Kwon et al. (2001) collectively arranged the Korean fauna of Miridae into 7 subfamilies, 84 genera, and 209 species, but many species have been believed to remain unrecorded. During recent the recent study of Miridae, we found three unrecorded species, Apolygus roseofemoralis (Yasunaga 1992), Pachylygus nigrescens (Kerzhner 1977), Deraeocoris yasunagai Nakatani 1995. The brief information on them are presented with the photos of specimens. All specimens are deposited in NIAST.

Apolygus xanthomelas Yasunaga and Yasunaga 2000 is reported from Korea for the first time. It is larger than other congeneric species from Korea and has characteristic V-shaped pale parts on hemelytra surrounded by entirely black clavus and posterior triangular marks of corium. It is similar in overall appearance to the Chinese congeneric species, A. ornatus (Zheng and Wang 1983), but it can be distinguished by the vesica, which has a long needle-shaped spicule reaching the apex of median sclerite and ventral sclerite, a slender and weak wing-shaped sclerite and a small sublateral sclerite. This species also distributes in Japan, but the Japanese population is a little different from that of Korea in usually having a pair of dark spots on calli. In this study, the detailed information is given with some photos of the male and female genitalia.