Yuriko Hirano

Three new species of Upogebiidae (Thalassinidea) from Iriomote Island, Ryukyus, Japan

Three new species of the genus Upogebia were recently collected in many specimens in the sandstone at the intertidal zone on Iriomote Island, Ryukyus, Japan. Upogebia saigusai sp. nov. is closely similar to U. snelliusi Ngoc-Ho, 1989; U. iriomotensis sp. nov. to U. baweana Tirmizi & Kazmi, 1979; and U. spinidactylus sp. nov. resembles U. carinicauda (Stimpson, 1860). Viele Exemplare dreier neuer Arten der Gattung Upogebia sind im Sandstein der Gezeitenzone von Iriomote Island, Ryukyu Inseln, Japan, gesammelt worden. Einander sehr ahnlich sind Upogebia saigusai sp. nov. und U. snelliusi Ngoc-Ho, 1989 sowie U. iriomotensis sp. nov. und U. baweana Tirmizi & Kazmi, 1979. U. spinidactylus sp. nov. hat Ahnlichkeit mit U. carinicauda (Stimpson, 1860).

A new record of Upogebia snelliusi Ngoc-Ho, 1989 (Thalassinoidea, Upogebiidae) from Iriomote Island, Ryukyus, Japan

[Upogebia snelliusi (Thalassinoidea, Upogebiidae) is recorded for the first time from Iriomote Island, Ryukyus, Japan. This species shows polymorphism in both males and females. Upogebia snelliusi (Thalassinoidea, Upogebiidae) wird erstmals von Iriomote-jima, einer der Ryukyu-Inseln (Japan) gemeldet. Sowohl Mannchen als auch Weibchen dieser Art sind polymorph., Upogebia snelliusi (Thalassinoidea, Upogebiidae) is recorded for the first time from Iriomote Island, Ryukyus, Japan. This species shows polymorphism in both males and females. Upogebia snelliusi (Thalassinoidea, Upogebiidae) wird erstmals von Iriomote-jima, einer der Ryukyu-Inseln (Japan) gemeldet. Sowohl Mannchen als auch Weibchen dieser Art sind polymorph.]

Classification of the Intertidal and Estuarine Upogebiid Shrimps (Crustacea: Thalassinidea), and Their Settlement in the Ryukyu Islands, Japan

Classification of the Intertidal and Estuarine Upogebiid Shrimps (Crustacea: Thalassinidea), and Their Settlement in the Ryukyu Islands, Japan Upogebiid shrimps (Crustacea: Thalassinidea) inhabit sandstones exposed on the intertidal zone of two of the islands of the Ryukyu Arc, Japan (islands located between 24°N, 123°E and 28°N, 129°E). The upogebiids here are morphologically similar; so, their classification is open to debate. In addition, when the upogebiids settled on the Ryukyu Arc has not been studied till date. Based on morphological features, we suspect that six stone upogebiid species are distributed in the Ryukyu Arc. This hypothesis was tested by molecular phylogenetic analysis of mitochondrial DNA markers. Furthermore, Bayesian evolutionary analysis, which was used to estimate TMRCA (time to most recent common ancestor) of each upogebiid, showed that stone upogebiids diverged 5-15 Ma (second half of the Miocene). Stone upogebiids may have occurred in the islands near the equator 5-15 Ma. On the contrary, Bayesian analysis indicated that the time of ‘intraspecific’ divergence varied from 1.15 Ma to 0 Ma, suggesting that stone upogebiids may have settled in the Ryukyu Arc from the Pleistocene to the present. In Iriomote Island, sedimentary layers suitable for burrowing occurred on the shores from the west to the northern half of the island, but not on the east. The Ryukyu Arc was a passive continental margin until the beginning of the Pleistocene, but the warm Kuroshio current completely separated the Ryukyu Arc from the Eurasian continent about 1.55 Ma. With subduction of the Ryukyu Arc northwestward, sedimentary layers for burrowing may have appeared on the ‘front’ of the island (i.e. on the shores from the west to the north), thereby providing suitable habitats for the stone upogebiids to settle, since 1.15 Ma.

Description of the male of Upogebia miyakei from Ryukyu Islands, Japan (Decapoda: Thalassinidea: Upogebiidae)

The small upogebiid shrimp, Upogebia miyakei, was originally described from a female collected from Ishigaki-jima Island, Ryukyu Islands, southern Japan. However, no male specimen has been reported since the discovery of the holotype. During surveys at Iriomote-jima Island and its type locality, both females and males of U. miyakei were collected from the intertidal zone. Based on this material a full description of the male is given, and comparison with the female reveals the sexual dimorphic characteristics. The palm of the first pereiopod of male specimens is about 1.5 times wider than that of females. In male specimens, one or two spines are present on the dorsal margin of the palm of the first pereiopod, while three to six sharp spines are found on female specimens. This species is compared here with Upogebia lincolni/from Java, Indonesia.