Hunter–gatherer occupations of small islands are rare in world prehistory and it is widely accepted that island settlement is facilitated by agriculture. The Ryukyu Islands contradict that understanding on two counts: not only did they have a long history of hunter–gatherer settlement, but they also have a very late date for the onset of agriculture, which only reached the archipelago between the eighth and thirteenth centuries AD. Here, we combine archaeology and linguistics to propose a tripartite model for the spread of agriculture and Ryukyuan languages to the Ryukyu Islands. Employing demographic growth, trade/piracy and the political influence of neighbouring states, this model provides a synthetic yet flexible understanding of farming/language dispersals in the Ryukyus within the complex historical background of medieval East Asia.

Three new species of echinoderid kinorhynchs are described from Daidokutsu, a submarine cave in Ryukyu Islands, Japan. Echinoderes gama sp. nov. is characterized by the presence of middorsal acicular spines on segments 4–8; lateroventral acicular spines on segments 7–9; lateroventral tubes on segment 5; sublateral tubes on segment 8; laterodorsal tubes on segment 10; and type-2 gland cell outlets in subdorsal and lateroventral position on segment 2. Echinoderes kajiharai sp. nov. is defined by the presence of middorsal acicular spines on segments 4, 6, 8; lateral accessory acicular spines on segment 9; lateroventral acicular spines on segments 6–8; lateroventral tubes on segments 2 and 5; midlateral tubes on segment 10; and type-2 gland cell outlets in laterodorsal position on segments 2 and 5, and subdorsal position on segments 8 and 9. Echinoderes uozumii sp. nov. is characterized by the presence of middorsal acicular spines on segments 4 and 6; lateroventral acicular spines on segments 6–9; lateroventral tubes on segments 2 and 5; sublateral tubes on segment 8; laterodorsal tubes on segment 10; type-2 gland cell outlets in subdorsal and lateral accessory position on segment 2; and blunt, short pectinate fringe teeth of primary pectinate fringe on segment 1. In addition, the Echinoderes multiporus species group including E. kajiharai sp. nov., and the Echinoderes bispinosus species group including E. uozumii sp. nov. are established. Furthermore, the distribution of the two species groups and the origin of Echinoderes species in Daidokutsu are discussed.

The Ryukyu (Okinawa) Islands are situated in sub-tropical zone between the Japanese Archipelago and Taiwan. Although Okinawan people have a rich tradition of star lore, few studies have been undertaken on its relevance to subsistence, religion and the socio-political system. This paper is a first attempt to explore a systematic relationship between star lore (e.g. relating to the Pleiades) with agriculture, fishing, navigation and religious practice. This paper also considers the possibility of interpreting the nature of prehistoric and historical stone structures from the viewpoint of archaeoastronomy. This kind of analysis is likely to be fruitful, since the kingship of the Ryukyu Islands was strongly associated with sun worship.

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.

The estuarine hermit crab, Clibanarius ambonensis is reported from Iriomote Island, southern Ryukyu Islands, Japan. This is the first record of the species from outside Indonesian territory. Clibanarius ambonensis was found on prop roots or trunks of Rhizophora stylosa or on rocks adjacent to the trees, which were exposed to the air at low tide time. The habitat seems to distinguish C. ambonensis in the field from the other local congeners inhabiting estuarine and mangrove areas such as C. longitarsus and C. striolatus. The latter two species usually inhabit the sand or mud surface of the estuarine and mangrove areas.

Comparisons of corolla morphology were made between plants of Conandron ramondioides (Gesneriaceae) from 23 localities in Japan and Taiwan. Lobe-length to tube-length ratios were found to correlate with geographical distribution and support the recognition of two previously described varieties: var. ramondioides in mainland Japan (lobe length less than twice tube length) and var. taiwanensis from Iriomote Island (Japan) and Taiwan (lobe length more than three times tube length). Mitotic chromosomes were also observed but no differences were seen between accessions, all of which had 2n=32.