CRUSTACEAN RESEARCH ，NO. 22 : 55 -64 ， 1993

Distribution Distribution of freshwater caridean and prawns (Atyidae (Atyidae and ) from Southern Kyushu and adjacent islands ，Kagoshima Prefecture ，Japan

Hiroshi Hiroshi Suzuki ，Noboru Tanigawa ， Takayuki Nagatomo and E討i Tsuda Tsuda

Abstract. Abstract. - Seventeen of fresh- biogeographical line s， the Miyake and water caridean shrimps and prawns Watase lines ， have been drawn in the north- (Atyidae (Atyidae and Palaemonidae) are recorded ern area of the archipelago (Tokuda ，1969) . from mainland Kagoshima ， Uji Gunto ， This region also has an interesting oceano ・ Ohsumi Shoto and Tokara Retto ，Southern graphical character; the warm Kuroshio Japan. Japan. Distribution of three Macrobra- Current from the tropics flows northward to chium prawns: 凡1. equidens ， M. the Kyushu mainland along the Ryukyu latimanus latimanus and M. grac i/i rostre ， are newly Islands and divides into two substreams in recorded recorded in the surveyed areas by the the northeast part of the archipelago present present study. Though the fauna of the (Ekman ， 1953; Kawai ， 199 1). Thus ， the surveyed surveyed areas has many tropical and northern area of the Ryukyu Island s and the subtropical subtropical species ，it is characterized as southernmost part of Kyushu mainland ， a complex mixture of southern and north- which together form Kagoshima Prefecture ， ern ern species. In the Sendai ，恥 fanose and are thought to be interesting areas for 区imotsuki Rivers ， the longitudinal distri- biogeographical studies . bution bution of shrimps was also surveyed. The Many scientists have done researches on distribution distribution is affected by a dam or a the islands in the area . Kamita (1963 . 円1970 的) natural natural vertical wall as mentioned in reported 出tha 剖t the faunas of freshwater previous previous papers. The amphidromous shrimps on Tan 巴ga-shima 丸，Yaku ト-寸. species ， Caridina leucosticta ， C. serrati- Amami Ohs 凶shima are similar to those of rostris ， C. typus ，M. formosense ，and M. Middle and Southern Honshu . Shokita japonicum ， inhabited slow flowing reaches (1 975 . 1979) studied the fauna ，distribu- near the river mouth ， while the landlocked tions ， and life histories of freshwater Neocaridina Neocaridina denticu/ata and Pa/aemon shrimps in the Ryukyu Islands ，and discus- () paucidens were distributed sed their speciation and the formative proc- upstream from the dam or the steep ess of the fauna. The faunas in the islands reaches. reaches. of Tokara Retto and mainland Kagoshima are ，however ， not yet accurately surveyed . Knowledge of the fauna in these areas Introduction Introduction should provide important information on In In the region between Okinawa and the the biogeography of freshwater shrimps. main island of Kyushu ，many small islands are are sporadically located forming an arcuate archipel ago called the Ryukyu Island s Material and Method s This This reg ion has attr a cted the attent ion of Surveys were conducted at Uji-jima on biogeographers biogeographers for a long time ，and two May 14 ， 1986 ; at Shimokoshiki-jima on 56 56 H. SUZUKI ET A L.

June 4， 1987; and occasionally on mainland Pαrα ty αcompress αcompress α Kagoshima ， Ohsumi Shoto and Tokara (De Haan ， 1844) Retto Retto from 1990 to 199 1. Samples were Ohsumi Peninsula: 152 (1 2); 153 (4); 155 taken taken from inland waters such as rivers ， (5); 157 (17); 159 (3); 160 (60); 163 ponds ，and springs. In the Sendai ，Manose ， (20); 164 (7); 165 (I) . and Kimotsuki Rivers ， surveys on longitudi- Yaku-shima: 212 (l). nal nal distribution were also conducted. These Takara-jima: 226 (6). sample sites are indicated by solid circles in Fig. Fig. 1. Caridina typus H. Milne Edwards ， 1837 Shrimps were mainly collected by a nylon Satsuma Peninsula: 38 (1 7); 60 (1); 63 2 (8); 67 (4); 76 (10); 77 (9); 84 (1); 85 scoop net (mesh Icm ) with a mouth size of 100 100 x 65 cm. Additional samples were (2); s9 (l l) ; 91 (5); 92 (l); 95 (l 5). taken taken by a nylon landing net (mesh 0.025 Ohsumi Peninsula: 136 (7); 137 (2); 144 2 (5); 151 (I); 152 (3); 154 (6); 155 (3); cm ) with a mouth size of 30 x 20 cm Because Because atyid shrimps and palaemonid 157 (1 2); 160 (3); 163 (1); 164 (1); 171 prawns were found in aquatic grass beds ， (1) ; 181 (1); 182 (1). under stones ，between crevices ，and among Shimokoshiki-jima: 188 (6). fallen fallen leaves ， a sweeping method was Tanega-shima: 192 (3). applied applied for quantitative sampling. A total Kuchinoerabu-jima: 196 (6). of of ten net sweeps were made at each site. Yaku-shima: 198 (21); 199 (I); 200 (1) ; Sampling was not done at Suwanose-jima 202 (26); 203 (33); 205 (1); 206 (61) ; and Kodakara-jima of Tokara Retto since 208 (4); 209 (2); 210 (1 3); 212 (20); there there are no natural rivers ， lakes or ponds 213 (2). on these islands. On Akuseki-jima ， the only Nakano-shima: 217 (22); 219 (3); 220 small small river has been modified to serve as the (7); 222 (13); 223 (2). domestic domestic water supply so likewise ，speci- Takara-jima: 225 (18); 226 (32). mens could not be collected. Caridina longirostris H. Milne Edwards ， 1837 1837 Results Results Satsuma Peninsu1a: 34 (I). Tanega-shima: Tanega-shima: 192 (2); 193 (l). In In the surveyed areas ，a tota1 of seventeen Yaku-shima: 205 (1). species species of freshwater caridean shrimps and prawns were collected ， belonging to four Caridina leucosticta Stimpson ， 1860 genera genera of Atyidae and two genera of Satsuma Peninsula: 8 (1 0); 13 (4); 14 (2); Pa1aemonidae 20 (I 0); 32 (3); 33 (I 6); 34 (2); 35 (2) ; The collected shrimps and prawns are 36 (82); 38 (1); 39 (9); 43 (45); 44 (3); 1isted 1isted be10w. The Arabic numerals shown 45 (29); 47 (25); 48 (1 0); 51 (1 1); 53 in in parentheses indicate the total number of (48); 58 (130); 59 (55); 60 (20); 64 (1); collected collected shrimps ， preceded by another 67 (17); 74 (22); 77 (29); 85 (4); 89 Arabic numeral indicating samp1ing sites. (33) ; 95 (5); 101 (6) ; 105 (1 5); 110 (I 19); 113 (13). Ohsumi Peninsu1a : 115 (20); 120 (56); Family Atyidae 122 (9); 125 (5); 129 (36); 132 (2); 134 A tyopsis spinipes (Newport ， 1847) (30); 135 (6); 137 (1 2); 139 (2); 141 Ohsumi Peninsula: 164 (1). (21); 151 (15); 157 (I 5); 159 (7); 164 Yaku-shima: 211 (2). (287); 166 (1); 167 (! 12) ; 168 (! 30); Kuchino-shima : 216 (1) . 169 (51); 171 (38); 172 (46); 173 (l); Nakano-shima: 217 (I 8); 218 (I) 175 (I I); 176 (18); 178 (2); 181 (1 1). FRESHWA TER SHRIMPS AND PRA WNS IN KAGOSHIMA 57

MAINLAND 1129 ・E KAGOSHIMA (Satsumo (Satsumo Pen. ond ond Ohsum Pen.)

'・，・. OHSUMI SHOTO !!'す Kuchinoerabu Kuchinoerabu -'b""... (q JImo ~ rn:'，}:.~~主臨t '(;'，:， ;"y Tan 旬。 --- shimo Yaku Yaku -shirr 四 .0 へ ・・ Kuchino- shlma 30 ・N 寸・ Q Nakano -shim 。 • Tai _r Q - jlmo " Suwano.. -jlma Aku..ki • Aku..ki -jlma Kodakara • Kodakara - jlma ・Takara - jlma 29 ・N ，

ぷml て1m 28 ・N

UJI UJI GUNTO Yoku Yoku - shimo Tonego - shimo 制Ujl. jlma MH 94

Nokono - shimo Kuchi no ・ shimo

5km ト司

Ikm Ikm ト寸 Kuchinoerobu - jlmo

Tokoro - jlm 。 Toiro ・jimo

L 225・~ J 22 匂 Ikm Ikm 226- 、、 L ト吋

Fig 目1. Map showing the sample sites (solid circles) in mainland Kagoshima ，Shimokoshiki-jima ，Uji-jima ， Ohsumi Shoto ，and Tok a ra Retto. Arabic numerals show the site number. I; the Sendai river ， II; the Manose river ，and III ; the Kimotsuki river. Note: “gunto" ，“ shoto" ，and “ retto" mean an insular group. “shima" and “jima" mean island. 58 H .SUZUKI ET AL

Tanega 寸uma: 192 (1 2); 193 (5) . 210 (2); 211 (38); 212 (1 3) ; 213 (7). Yaku-shima: 203 (13) ; 204 (2). Kuchino- shima : 214 (3); 216 (5) Nakano- shima : 217 (4); 219 (3) Caridina Caridina serratirostris De M an， 1892 Ohsumi Peninsula : 137 (1) ; 151 (2) ; 157 Macrobrachium australe (Guerin (1) ; 164 (4); 168 (1) . Meneville ， 1838) Shimokoshiki-jima: Shimokoshiki-jima: 188 (3) . Satsuma Peninsula: 45 (1). Yaku-shima : 203 (6); 204 (1); 205 (3) . Tanega-shima: 193 (5) . Nakano-shima : 217 (1); 219 (3) . Caridina Caridina japonica De Man ， 1892 Satsuma Peninsula : 12 (2) ; 65 (4) . Macrobrachium nipponense (De Ha an， Oh sumi Peninsula : 136 (1) ; 140 (6); 144 1849) (1 2); 145 (1 2); 146 (4) ; 150 (2) ; 152 Satsuma Peninsula: 13 (1); 14 (1); 45 (1) . (22); (22); 154 (4); 156 (1 7) ; 157 (1); 158 Macrobrachium japonicum (De Haan ， (1 3); 162 (7); 164 (7); 183 (9) . 1849) 1849) Sh imokoshiki-jima : 188 (30) . Satsum a Peninsula : 12 (1) ; 33 (5) ; 34 (1) ; Uji サima: 189 (2) . 64 64 (2) . Kuchinoerabu-jima : 197 (1) . Ohsumi Peninsula: 129 (7); 136 (1 2); 139 Yaku-shima: 199 (3); 200 (8) ; 202 (1) ; (9) ; 146 (1 1) ; 148 (2) ; 154 (10) ; 155 205 205 (8); 207 (1 6) ; 209 (4); 213 (1) . (3) ; 156 (4) ; 160 (1); 161 (2) ; 163 (2); Nakano-shima: 222 (2) . 164 164 (4) ; 165 (7); 176 (4); 17 8 (24) ; 182 Takara-jima: Takara-jima: 226 (20) . (9) . Neocaridina Neocaridina denticulata (De Haan ， 1849) Shimokoshiki ・jima: 187 (1 0) ; 188 (5) . Satsuma Peninsula : 20 (27) ; 54 (10); 55 Kuchinoerabu-jima: 195 (3) . (3); (3); 76 (3); 82 (4) ; 97 (52); 98 (225); Yaku ト.寸 1山lma 凶a広: 200 (1). 99 99 (8). Nakano-shima: 222 (2) . Oh sumi Peninsula : 116 (39) ; 117 (5) ; 118 Macrobrachium equidens (Dana ，1 8 52) 40); (40); 172 (2) ; 173 (4) ; 177 (57) . Tanega-shima : 190 (1) ; 193 (12) . Macrobrachium latimanus (Von Marten s， Family Palaemonidae 1868) Palaemon (Palaemon) paucidens Oh sumi Peninsula: 146 (6) De Haan ， 1844 Kuchinoerabu-jima: 197 (4) Satsuma Peninsula : 22 (57) ; 67 (1); 76 Yaku -s him a: 200 (1); 208 (9). (1 4) ; 79 (1 5); 80 (7) ; 81 (5) ; 83 (13) Ma c robrachium formosense Bate ， 1868 Ohsumi Peninsula: 155 (67); 157 (1 26); Sat suma Peninsula: 8 (3); 12 (1 4) ; 13 (8); 159 159 (23) ; 160 (2) ; 164 (1); 170 (34) ; 14 (3) ; 16(4) ; 19 (1) ; 30(5) ; 32(2) ; 33 178 178 (2) ; 182 (1) . (4) ; 34 (9) ; 35 (34) ; 36 (1 4) ; 37 (1 6) ; Tanega-shima : 191 (27) ; 192 (1) ; 194 38 38 (I 6); 39 (3); 40 (1); 43 (I 6); 45 (38) ; (10) (10) 46 46 (7) ; 47 (3) ; 48 (5) ; 49 (3) ; 50 (5) ; 51 Yaku- shima : 198 (46) ; 201 (11) ; 202 (5); (1 09) ; 53 (5); 58 (17) ; 59 (56) ; 60 (10) ; 203 203 (1 4); 204 (1 3) ; 205 (22) ; 213 (1). 61 61 (1) ; 62 (1 1); 63 (5); 64 (9) ; 65 (5); Macrobrachium lar (Fabricius ， 1798) 66 (2) ; 67 (34); 68 (5); 69 (1 1) ; 71 (1) ; Satsuma Peninsula : 76 (2) . 72 (1) ; 73 (4) ; 77 (5); 86 (21); 89 (4) ; Ohsumi Peninsula : 146 (4) . 90 (5) ; 95 (I I); 1 10 (3) . Kuchinoerabu サim a: 195 (7); 197 (3) Ohsumi Peninsula : 125 (7) ; 12 8 (4) ; 129 Yaku- shima : 202 (5) ; 203 (3) ; 205 (2); (1 7) ; 131 (4) ; 132 (3) ; 133 (30) ; 134 2 06 (42) ; 207 (4) ; 208 (1 0) ; 209 (9); (28) ; 136 (1); 137 (3) ; 138 (1); 139 FRESHW A TER SHRIMPS AND PRA WNS IN KAGOSHIMA 59

Table Table 1. A summary of the distribution of freshwater shrimps and prawns in mainland Kagoshima ， Shimokoshiki-jima ，Uji-jima ， Ohsumi Shoto ， and Tokar a Retto . No wa s collected at Taira-jima . oz 032 O EE4vazg。 手 吉 。 OEωSEE Locality Locality name oEE?EE?228x3a522ω・EEoEasω s?EO。 E2"'。一宮， OE--'O』ちト。 cov-oz。 O0官吉担ε-?き 話。↑コ話。〉・8 E2ω 歪 δ 一ヲ Famlly Famlly name Species name ↑ Atyidae Atyidae •• • • • • ••• ••• • • ••• ••• • • • ••• ••• ••• Palaemonidae Palaemonidae •• • •• • ••••• • • • • •• • •• • ••• ••• • •

(10); (10); 141 (9); 147 (1 0); 149 (52); 151 P. paucidens ，M. lar ，M. japonicum ，and M . (20); (20); 155 (6); 157 (1 2) ; 159 (7); 160 formosense . On the basis oftheir geographi- (5); (5); 163 (1 6); 164 (53); 166 (1); 167 cal distribution these nine species could be (269); (269); 168 (1 16); 169 (44); 171 (1 1); divided into four groups as follows (Table 172 172 (1 20); 173 (36); 174 (2) ; 175 (1 8); 1); 1) species distributed from mainland 176 176 (67); 178 (2); 181 (9); 182 (9) . Kagoshima (Satsuma and Ohsumi Penin- Tanega-shima : 191 (1); 192 (4); 193 (1 2); sula) to the Tokara Retto ， that is C. typus ， 194 194 (3) . C. japonica ，M. lar ，and M. japonicum ， 2) Yaku-shima: 203 (1); 204 (3) . species distributed from mainland Kago- shima to the Ohsumi Shoto ， that is C. Macrobrachium gracilirostre (Miers ， 1875) leucosticta ， P. paucidens ，and M. formosen- Kuchinoerabu サima: 197 (2) . se ， 3) species distributed from the Ohsumi Nine out of seventeen speci 巴s were abun - Peninsula to the Tokara Retto ， that is P . dant (n >> 23); P. compressa ， C. typus ， compressa ，and 4) species distributed only C. C. leucosticta ， C. japonica ， N. denticulata ， on mainland Kagoshima ， that is N. 60 60 H .SUZUKI ET A L.

300 24y' ，， ，， で/ J E} ，， 2OQ 円以ハ 凶白コト一ト」《 21 ~~・ 4守 l'; ~ l';

V 28 。 M. nlPpommse 0 長 ・・・ M. formos fJ nS fJ ω EI 園田 • c. Itlucosflcfa dEo-- 圃 N. N. denflcul σfa

• P. paucld fJ ns 茎 0 1: .1 。 50 ' 100 FROM TH E R IVER -M OUTH• (km) DISTANCE

Fig .2. Longitudinal di stribution and abundance of inl a nd water shrimps and prawns in the Sendai Rive r. Arabic Arabic numerals show the site number denticulata. denticulata. 28 in Fig.2 and 170 in Fig.4). The other eight sp 巴cies were less abun- dant (n < 23); A. spinipes ， C. longirostris ， C. C. serratirostris ，M. αustrale ，M. niJ フ'ponense ， Discussion M. equidens ，M. latimanus ，and M . gracili - Geographical distribution: The number rostre. rostre. Most of them may be rare in the of species of shrimps varied in the surveyed surveyed surveyed area ， while M. nipponense may be islands and peninsula (Table 1). The num- under represented because of the sampling ber of species of birds or butterflies is technique technique used. known to be affected by island size (= the Longitudinal Longitudinal distributions in the Sendai ， area of an island); large islands have many Manose and Kimotsuki Rivers : Caridina species of (MacArthur & Wilson ， leucosticta leucosticta and M. formosense showed wide 1967 ; Kimoto ，1979) . In the case of fresh- longitudinal longitudinal distributions upstream from water shrimps ， the whole area of inland the the river mouth in the three surveyed rivers water must be used as the index of island (Figs .2-4) . Landlocked N. denticulata size for our analysis . However an accurate were found in the middle or upper reaches. estimate of the area of inland water is not No shrimps or only landlocked P. yet available for each island ， but the area of paucidens paucidens are found at the sites in the steep inland water should be related to the area of reaches reaches (sites 15 in Fig.2 and 56 in Fig. 3) an island . Therefore the area of an island or and upstream from a dam (sites 17 -18 ，21 - a peninsula may be used as the index of FRESHW A TER SHRIMPS AND PRA WNS IN KAGOSHIMA 61

300

{E)

内 ハnv r V 凶 』 O コト一ト

11ハハ Jd V V 。 号~~ 1. C. Isucostlcta M. formossnss . ;ta i;ta • N. dsntlculata 。 10 20 • • 30 DISTANCE FROM THE RIVER- MOUTH (km)

Fig .3 . Longitudinal distribution and abundance of inland water shrimps and pr a wns in the Mano se River Ar abic numerals show the site number island island size in the case of these freshwater Strait between mainland Kagoshima and shrimps. shrimps. The number of species of shrimp Ohsumi Shoto ， while P. paucidens was dis- showed a positive correlation with area ， tributed northward from the Watase line ， having a high coefficient of correlation (r = drawn at the Tokara Stra It between the 0. 92) (Fig .5). Thus ， in the case of fresh- Ohsumi Shoto and Tokara Retto . These water water shrimps ， the number of species in- two species are thought to extend their habiting habiting an island is thought to be affected distribution southward by means of the by island size in the same way as for birds land bridge. Therefore ， the extension of the and butter f1 ies . distribution of N. denticulata and P. The shrimps obtained in this survey were paucidens may be affected by the formation mainly tropical and subtropical species. of the Ohsumi and Tokara Straits. The occurrences of temperate or continental In the present study three Macrobrachium species ， such as N. denticulata ， P. paucidens prawns ，M. equidens ，M. latimanus and M. and M. nipponense ， suggest that the fauna is gracilirostre ，were confirmed to inhabit the a complex mixture of southern and northern Ohsumi Shoto (Tanega-shima ，Yaku-shima species species as mentioned by Shokita (1975 ， and Kuchinoerabu-jima) (Table 1) . Previ- 1979). 1979). The present study made it cI ear that ous reports clarified the distribution of these N. N. denticulata was distributed northward species southward from Okinawa jima from the Miyake line ，drawn at the Ohsumi (Kamita ， 1963; Shokita ， 1975 ， 1979; Sho- 62 62 H. SUZUKI ET A L. ，! ，， l 300 ''』 ''fi 11'! i i'' ，' ，， ，， 5200 w 凸 コ ト ~ 100 」 <(

C. C. loucostlcto -.1. -.1. a・ M. formosons (J E E 」阻 L. ・・ C. sorrotlrostrls N. N. dontlculot σ E ー自白・--田ー」 • c. typus M JnF，gσpuoc nAka -ce un ms A • p. 且 --nvEE J2Rlov ow RO M FPHM O HU T' uH DISTANCE THE 』

Fig.4. Fig.4. Longitudinal distribution and abundance of inland water shrimps and prawns in the Kimotsuki Rive r. Arabic numerals show the site number .

kita kita & Nishijima ，1976 ，1977) . Female M. prawns could extend their distributions to equidens equidens produce some thousands of small the Ohsumi Shoto by larval dispersal eggs eggs (average diameter = 0.79 mm) ，and through the Kuroshio Curren t. release release pelagic larvae which develop in Though seven southern species were waters waters with 24 .5-35 .0 % 0 salinity (Ngoc ， found to be common to the Satsuma Penin- 1976; 1976; Shokita ，1979) ，however ， the environ- sula of mainland Kagoshima and Yaku- mental mental factors affecting larval development shima ， ten were found to be common to the of M. latimanus and M. gracilirostre are still Ohsumi Peninsula of mainland Kagoshima unknown. Shokita (1 979) reported that the and Yaku-shima. These results suggest that females females ofthese species produce two to three Ohsumi Peninsula is influenced more thousand small eggs (average diameter = O. strongly by the Kuroshio Current ，and that 69 69 mm). Therefore ， the larvae of these the climatic conditions of this area are more shrimps shrimps are inferred to develop in sea water tropical than those of the Satsuma Penin- with with similar qualities as those for M. sula. equidens. equidens. The three Macrobrachium Although the distributions of C. japon- FRESHW A TER SHRIMPS AND PRA WNS IN KAGOSHIMA 63

100 100

Ohsumi Ohsumi ~ 内n.~ ω nv 凶 -υ 50ts • 四no Nokono-shlmo_ _Kuchinoerobu Pen. 凶仏 ・・ Jimo ω 5himokoshiki- -• jlma LL 。 Kuchino- • shimo 区凶 mE コ Z

O.I~ 0.1 10 100 1000 10000 THE ISLAND AND PENINSULA AREA ( km 2 )

Fig .5. Relationship between the number of species of shrimp and the area of surveyed islands and peninsula . 80th axes are expressed as the common logarithmic scales.

ica ，M. lar ，and M. formosense overlapped faunal composition in the surveyed areas in in the east Asian region (Holthuis ， 1950; may be affected by island size ， the Kuroshio Shokita ，1975 ，1979) ， the two species ， C. Current ， the form of the river ，and the japonica japonica and M . lar ， are also distributed in migratory ability of each species. the the islands of Tokara Retto but M. for- Longitudinal In distribution: the three mosense mosense was not found in these islands surveyed rivers ， the amphidromous species ， (Table (Table 1). Similar results were reported in C. leucosticta ，M. formosense ， C. serratiros- previous previous studies (Shokita ，1975 ， 1979; Sho- tris ， C. typus ， and M .japonicum ， were kita kita & Nishijima ， 1977). Hamano & Haya- found to inhabit slow flowing reaches near shi shi (1 992) reported that the juveniles of C. the river mouth (Figs. 2 -4). On the con- japonica japonica climbed a vertical wall in the trary ，only landlocked N. denticulata and P. Shiwagi Rivulet ，Tokushima. Lee & Fielder paucidens were distributed upstream from (1 979) also observed the vertical climb of the dam or in the steep reaches. The longi- M. australiense on a6 m high weir. The tudinal distribution in these three rivers different different distributions found among the would be also affected by a dam or a natural three three species ， C. japonica ， M. lar and M. V 巴rtical wall as reported by previous studies formosense ，may have resulted from the (Kamita ， 1970; Shokita ，1979 ，1982 ，1990 ; different 巴cological characteristics found in Miya & Hamano ， 1988; Hamano & Haya - each species such as the process of larval shi ， 1992). recruitment ，c1 imbing ability of juveniles In the Sendai and Kimotsuki Rivers ， P. and survival of juveniles after settlement paucidens ， instead of N. denticulata ，was These hypotheses require future study. distributed in the artificial lake or in the As mentioned above ， the geographical areas upstream from the dam (Figs.2 ，4) . distributions distributions of freshwater shrimps and the Palaemon paucidens was distributed further 64 64 H. SUZUKI ET AL. upstream in the surveyed rivers than N. Sonoyama Shoten ，Matsue . (In Japanese) Kawai ，H . ed. ，199 1. Nagare to seibututo - suisan denticulata. denticulata. However ， N. denticulata was kaiyohgaku tokuron -. 410 pp .，Kyoto Univer- found to inhabit more upstream locations sity Press ，Kyoto . (In Japanese) when P. paucidens was absent (Fig. 3). Kimoto ，S. ，1979 . Minami no shima no ikimonota- chi. chi. 203 pp .， Kyoritsu Shuppan ， Tokyo. (In Miya & Hamano (1988) reported that after Japanese) a dam has been bui 1t across the Yukinoura Lee ，C . L. & Fielder ， D. R. ，1979. A mass migration of of the freshwater prawn ，凡 1acrobrachium aus- River ，Nagasaki ， N. denticulata expanded traliense Holthuis ， 1950 ( ， its its distribution into the artificiallake on the Palaemonidae) . Crustaceana ， 37 (2): 219 -222 . MacArthur ，R .& Wilson ，E .0 . ，1967. The theory of rive ln the Yukinoura River P. paucidens r. r. island biogeography. 203 pp .， Princeton Uni- was absen t. These two landlocked species ， versity Pre ss ，Princeton ， N. J. therefore ，may compete with each other for Miya ， Y. & Hamano ，T .， 1988. The in t1 uence of a dam having no fishway on the distribution of habitat habitat in the upper reaches of the river. decapod in the Yukinoura River ， Lastly ，the longitudinal distribution of Nagasaki ， Japan. Nippon Sui sa n Gakkaishi ， 54 54 (3): 429 -435 . (In Japanese) shrimps in a river may be affected by the Ngoc-Ho ，N .，1976 . The larval development of the form of the river and the life history of each prawn Macrobrachium equidens and Macro- specles. specles. brachium sp. (Decapoda: Palaemonidae) ，rear- ed ed in the laboratory. Journal of Zoology ， London ，178 ; 15 - 55 Shokita ，S. ，1975 . The distribution and speciation Acknowledgments of the inland water shrimps and prawns from the the Ryukyu Islands- l. Bulltein of Science and We thank D r. C. L. McLay of the Univer- Engineering Division ， of University the Ryu- sity sity of Canterbury ， D r. S. Shokita of the kyus ，No. 18 : 115 -136 . (J n Jap ane se) 一一一一， 1979 . The distribution and speciation of University of the Ryukyus ， D r. R . B. Man- the inland water s hrimps and prawn s from the ning of the Smithsonian Institution ，and Ryukyu island s -I I. Bulltein of Science and Engineering Engineering Division ，Univer sity of the Ryu- M r. E. A. T. Floreto of Kagoshima Univer- kyus ，No .28: 193 -278. (In Japanese) sity ， for critically reading the manuscrip t. ー一一一， 1982 . Longitudinal di stribution of car- idean idean shrimps (Atyidae and Palaemonidae) in the the river s of the R yukyu Island s. Aquabiology ， No. No. 18: 57 -63. (J n Japanese) 一一一 一， 1990. Inland-water macrofauna and their Literature Literature Cited t1 uctuations in the northern oart of Okinawa lsland ， the Ryukyus. 8iological Magazine of Ekman ，S .，1953 . Zoogeography of the sea. xiii + Okinawa ， 27: 3 -13. (J n Japane se) 417pp. 417pp. Sidgwick and Jackson Limited ，Lon- 一一 一 & Nishijima ，S .， 1976. Faunallist of inland- don water malacostrac a of Amami group ， the Ryu- Hamano ，T .& Hayashi ，K. -l. ，1992 . Ecology of an kyu Islands . Ecological Studies of Nature atyid atyid shrimp Caridina japonica (De Man ， Conservation of the Ryukyu Islands ，2: 31 -38 . 1892) 1892) migrating to upstream habitats in the 一一一 一 & 1977. Land and inland-water Shiwagi Shiwagi Rivulet ， Tokushima Prefecture. crustaceans of northeastern Ryukyus ， the Ryu- Re sea rches on Crustacea ， 21: 1 - 13. (In kyu Islands . Ecological Studies of Nature Japanese) Japanese) Conservation of the Ryukyu Isl ands ， 3: 185 - Holthuis ， L. B.， 1950. The Decapoda of the Siboga 202. Expedition. Expedition. Part X . The Palaemonidae col- Tokuda ，M .，1969 . Biogeography . 199 pp . ，Tsukiji lected lected by the Sibog a and Snellius expeditions ， Shokan ，Tokyo . (In Japane se) with with remarks on other species . 1. Subfamily 9 Pal ae moninae . Siboga Expeditie ，39a : 1 -268. Kamita ，T. ， 1963. Fresh-water shrimps and prawns of of Amami-oshima ，Yaku-shima and Tanega- M arine 8iol og ic alL aboratory ， Faculty of Fish- s hima. 8ulletin of the Shimane Universitv eries ，Kagoshima University ，Shimo arata 4-50 -20 ， (Natural (Natural Science) ， No. 13 ・ト28 . (In Japanese) K agos hima 890 ，J a pan 一一一一， 1970. Studies on the 什esh-water shrimps ， prawns prawns and crawfishes of Japan. 213 pp. ，