Eight species of Chironomidae (Diptera) which are new to Korea are described with illustrations. They are extremely rare species in Korea, as only one or two specimens have been collected since 1977 throughout the country. Microchironomus tener, Stictochironomus akizukii and Paratendipes nubilus belong to subfamily Chironominae, and the other five species: Diplocladius cultriger, Limnophyes minimus, Metriocnemus fulvofasciatus and Parametriocnemus stylatus belong to subfamily Orthocladiinae.

Two new species of the genus Doridicola are described as associates of opisthobranch mollusks from Korean intertidal waters: Doridicola virguatus n. sp. associated with the notaspidean Pleurobranchaea japonica Thiele and D. portincola n. sp. associated with the nudibranch Hoplodoris armata (Baba). This is the first record for the copepod associates of opisthobranch mollusks from Korea.

A new genus Goodingius is proposed to incorporate Hemicyclops adhaerens(Williams), H. arenicolae Gooding, H. elongatus Wilson and H. subadhaerens Gooding, all of which bear the six-segmented female urosome, three mandibular elements (or three elements plus one rudimentary setule), five setae on the first antennular segment, and no inner coxal seta of leg 4. The genus Giardella Canu, a sister taxon of Goodingius, is redefined as possessing eight elements on the third exopodal segment of leg 3, only a single inner seta on the second endopodal segment of leg 4, four spines on the third endopodal segment of leg 4. To the genus Giardella, Hemicyclops caissarum Kihara and Rocha and H. carinifer Humes are assigned, in addition to Giardella ricoensis n. sp., Giardella callianassae Canu, and G. thompsoni A. Scott. Keys to the species of both genera are provided.

Eight calanoid species of 4 genera in 4 families are reported from the various brackish waters such as estuaries, brackish-water lakes, and coastal marshes in South Korea. Among them, Eurytemora affinis (Poppe) and Acartia (Acanthacartia) tsuensis Ito are newly added to Korean copepod fauna. Collection data, brief descriptions, illustrations and distribution maps for the eight species are prepared. A key to the genera and species of the brackish-water calanoids from Korea is also presented.

As a result of the faunistic study on the subterranean cyclopoid copepods, four species of three genera in the family Cyclopidae are reported from nine limestone caves and a lava tube in South Korea: Megacyclops magnus (Marsh, 1920), Acanthocyclops orientalis Borutzky, 1966, A, robustus (Sars, 1863) and Diacyclops suoensis Ito, 1956, all of them new to Korean fauna. This paper deals with the taxonomic accounts and illustrations of the four species with the redescription of A. orientalis. This is the first taxonomic study on the cave-dwelling cyclopoid copepods from Korea.

Two new marine sponges in the family Chalinidae, Haliclona (Haliclona) uljinensis n. sp. and Haliclona (Reniera) hongdoensis n. sp., are collected from Uljin and Hongdo Island, Korea during 2004-2007. H. (H.) uljinensis n. sp. is closely related to H. (H.) oculata in type of spicules. However, ectosomal skeleton of H. (H.) uljinensis n. sp. is reticulated and isodictyal reticulated type but H. (H.) oculata has not any dermal specialization in skeleton. The growth form of H. (H.) uljinensis n. sp. is thin encrusting with numerous cylindrical tubes on the surface but H. (H.) oculata is solid branch form. Haliclona (R.) hongdoensis n. sp. is closely related to H. (R.) aquaeductus in skeletal structure and growth form. However, oxeas of H. (R.) hongdoensis n. sp. are larger than H. (R.) aquaeductus's.

Some hydromedusae were collected from Gijang (Busan), Yeounggwang, Munseom (Jejudo Is.) and Shinhangman with Issacc-Kidd Midwater trawl net or by SCUBA diving from 2001 to 2003. They were identified into five species of five families in three orders and are new to the Korean fauna. Bougainvillia ramosa (van Benenden, 1844) of the family Bougainvilliidae in the order Anthomedusae, Phialidium hemishaericum (Linne, 1767) of the family Campanulariidae and Aeguorea macrodactyla of the family Aequoreidae in the order Leptomedusae, Diphyes dispar (Chamisso and Eysenhardt, 1821) of the family Diphydae and Abylopsis tetragona (Otto, 1823) of the family Abylidae in the order Siphonophora. With a result of this work, the Korean hydromedusa fauna consists of 31 species of 18 families in six orders.

Three ichneumonid wasp species of the tribe Poemeniini (Ichneumonidae: Poemeniinae) are redescribed from Korea: Cnastis assimilis (Uchida) (new Korean record), Deuteroxorides orientalis (Uchida) and Eugalta ablimarginalis (Uchida) (new Korean record). A key to the Korean species of Poemeniini, photographs of diagnostic characters, distributional data and host records are provided.

We report four genera and species, Aoplus rufulus (Uchida, 1925), Bystra kusukusensis (Uchida, 1929), Setanta apicalis (Uchida, 1926), and Zanthojoppa speciosa (Uchida, 1926), of the subfamily Ichneumoninae for the first time in Korea. Photographs and descriptions are provided to aid their identification.

Two hippolytid shrimps, Spirontocaris spinus (Sowerby, 1805) and Lebbeus unalaskensis (Rathbun, 1902) are described on the basis of material collected from the deepwater of the East Sea, Korea at 310-810 m. The former has been incorrectly known as Spirontocaris arcuata Rathbun, 1902 in Korea and the latter is a new member of the Korean fauna. Morphological and distributional accounts of these species are presented with illustrations.

The first zoeal characters of plagusiine crab Plagusia dentipes De Haan, 1835, belonging to the family Grapsidae, is described and illustrated in detail based on laboratory-hatched material from an ovigerous female collected from Bomok, Seogwipo in the Jejudo Island. Morphological comparison is made with previous description of Plagusia dentipes from Japan. The first zoea of Plagusia dentipes can be readily distinguished from those of two species of Plagusia chabrus and Plagusia depressa by having 2 aesthetascs and 3 simple setae on the antennule, and 8 setae on the coxal endite of the maxilla.

A new marine sponge in the family Microcionidae, Ophlitaspongia yongjeongensis n. sp. is collected from Yongjeong-ri, Hyeongyeong-myeon, Muan-gun, Korea during 2005-2007. O. yongjeongensis n. sp. is closely related to O. reticulata in growth form (shape and color). However, the thick style and slender style of O. yongjeongensis n. sp. are larger than O. reticulata's (Bergquist and Fromont, 1988).

The kleptoparasitic spider subfamily Argyrodinae in Korea is reviewed with detailed illustrations and SEM photographs of male palpal organs. Five species belonging to four genera of Korean Argyrodinae spiders are redescribed and Argyrodes miltosus Zhu and Song, 1991 is synonymized with A. miniaceu. A key to the species of the Korean Argyrodinae spiders are also provided.

Two euplotid ciliates collected from the estuarine littorals in Korea were identified as Euplotes vannus ($M\ddot{u}ller$, 1786) and E. parawoodruffi Song and Bradbury, 1997. These species are reported taxonomically for the first time from Korea. These two species are redescribed with illustrations, photos and biometry based on live and silver impregnated specimens. Diagnostics of each species are as follows. E. vannus: size in vivo $94-111{\times}55-75{\mu}m$ (average $103{\times}60{\mu}m)$, adoral zone of membranelles (AZM) 70% of cell length with 57-74 adoral membranelles (AM) and terminating close to hook-shape, macronucleus (Ma) C-shaped with twisted foot-like, 10 frontoventral (FVC), 5 transverse (TC), 4-7 (average 5) caudal cirri (CC), 9-10 dorsal kineties (DK), mid dorsal kinety with 15-22 cilia; silver-line system single vannus type. E. parawoodruffi: size in vivo $125-163{\times}72-100{\mu}m$, (average $141{\times}87{\mu}m$), dorsally strongly arched, body shaped reserved triangular. AZM 67-83% of cell length with 60-85 AMs, 9 FVC, 5 TC, 4 CC, 9 DK; mid-dorsal kinety with 20-30 cilia, double-eurystomus type, T-shaped Ma with equal sized right and left arms or right arm shortened slightly.

Eschatarchia lineata Warren, the sole member of the genus, is reported for the first time in Korea. Diagnosis of the genus and species is provided with brief descriptions of adults including male genitalia.

The genus Dinothenarus Thomson, represented by D. chrysocomus (Mannerheim, 1830), is recorded for the first time from the Korean peninsula.

A corophiin species, Sinocorophium sinensis (Zhang, 1974) collected from oyster beds of Sacheon, southern coast of Korea is described and illustrated. Specimens of present study look more similar to those of China than those of Japan.

We here report Apocorophium acutum (Chevreux, 1908) with description and illustrations for the first time in Korea. Specimens of present study show morphological differences in ventral processes of peduncular segment 5 of antenna 2 with the same species from Europe and Atlantic coast of North America.

Some sea stars were collected from the coast of Seogwipo, Jejudo Island by using the fishing net at April 2003, and were identified on the basis of their morphological characteristics. Among them, Paragonaster ctenopes Sladen, 1889 belonging to family Goniasteridae, order Phanerozonia is newly recorded from Korea. Twenty two species of asteroids are reported to be distributed in the Jejudo Island of Korea.