taxonID	type	description	language	source
C9395B008B5FFFD3F91A1258D7034F18.taxon	description	Native distribution: Western part of the main islands of Japan (Toyota et al. 2014; Mitsugi et al. 2017; Mitsugi and Suzuki 2018). Remarks: Neocaridina denticulata, the type species of this genus, was considered the only native species of the genus in the main islands of Japan (Cai 1996; Liang 2004) until the publication of the name N. ikiensis for specimens from Iki Island, off the northern coast of Kyushu (Shih et al. 2017). Key characters of N. denticulata include its relatively long rostrum, which generally reaches beyond the end of the antennular peduncle; the third and fifth pereiopods do not display sexual dimorphism; the endopods of the male first pleopods are distinctly broad, about 1.2 times as long as wide, and the appendix interna of the male second pleopods is short, not reaching the end of the endopod (Cai 1996; Liang 2004). Our specimens agree well with these characters (Figs. 4, 5). Based on our study supported by molecular evidence, the species is confirmed to be distributed in the main islands of Japan, as well as the Jiangsu (Taihu Lake and Nanjing City) and Yunnan Provinces of China (Fig. 3). Due to the limited samples across China used for genetic comparison, we are unable to comment if these populations in China are native. When describing two new Neocaridina species from Taiwan, Shih and Cai (2007) presented genetic relationships by examination of COI sequences of their new species with a few known species from Taiwan, China and Japan. In their study, Neocaridina denticulata was represented by specimens from Lake Biwa (AB 300191). Nishino (2017) and Fuke et al. (2021) questioned the validity of the species name used for the genetic material, as N. denticulata was presumed to be extinct from Lake Biwa before the incidental introduction of N. davidi in the 2000 s, and N. davidi has since spread widely in and beyond the lake (Nishino and Niwa 2004). Based on molecular and morphological evidence, however, Onuki and Fuke (2022) recently confirmed that both species are found in Lake Biwa. With more samples available, our current study shows that the Lake Biwa specimen (AB 300191) is genetically closely clustered with many N. denticulata specimens from western Japan and China (Jiangsu and Yunnan) (Fig. 3). The attribution of the name N. denticulata to this specimen by Shih and Cai (2007) was therefore correct. Nagai and Imai (2021) reported a species of Neocaridina from Kakinohana spring, Nanjo City, Okinawa Island, the Ryukyus. They tentatively assigned their specimens to “ N. davidi Type II (N. davidi koreana?) ” based on COI sequences. These sequences shared only one haplotype and genetically clustered together with our N. denticulata specimens collected from Shiga (Lake Biwa), Gifu, Hyogo, Okayama, Shimane, Hiroshima, and Yamaguchi (Fig. 3), as well as one of Fuke et al. (2021) ’ s Oita specimens (LC 612373) (Nagai and Imai 2021: fig. 3). This result suggests that the Okinawa specimens should be assigned to N. denticulata, and this species also occurs in Oita. The Chinese material (from Henan Province) named as N. davidi koreana (MW 069609 – MW 069622) in Zhou et al. (2021) should also be assigned to N. denticulata. Levitt-Barmats et al. (2019) reported the occurrence of “ N. denticulata ” in Israel. According to the authors, the Israeli specimens are most probably N. denticulata, as they showed no sexual dimorphism in the third pereiopods. However, their COI sequences of 15 specimens (MN 336485 – MN 336499) from Japan (Okayama), cluster into two distinct clades, with three specimens belonging to N. denticulata and 12 belonging to N. aff. denticulata (results not shown). In our study, these two species have also been identified from Okayama (Table 3). By including the longer Israeli COI sequences of Neocaridina (Table 2) into our phylogenetic tree (Fig. 3), all samples clustered well within the clade of N. davidi, except for one (MN 336458) from HaHula Nature Reserve, which belonged to N. denticulata. While this specimen may represent the first recorded introduction of N. denticulata outside its natural range (Japan and possibly China), we cannot exclude the possibility of mislabelling.	en	Shih, Hsi-Te, Cai, Yixiong, Niwa, Nobuaki, Yoshigou, Hidenori, Nakahara, Yasuhiko (2024): Integrative Taxonomy Reveals Freshwater Shrimp Diversity (Decapoda: Atyidae: Neocaridina) from Kyushu and Southern Honshu of Japan, with a Discussion on Introduced Species. Zoological Studies 63 (18): 1-30, DOI: 10.6620/ZS.2024.63-18, URL: http://dx.doi.org/10.5281/zenodo.14702283
C9395B008B55FFCEFA9D1338D40E4F38.taxon	description	Specimens examined: Japan: 6 males, cl 3.9 – 5.6 mm, ZRC 2023.0214, Sugo R., Yumesaki River system, Himeji City, Hyogo Prefecture, N 34 ° 56 ' 31.9 ", E 134 ° 38 ' 19.0 '', coll. N. Niwa, 14 Aug. 2015; 1 female, cl 4.0 mm, 1 female, cl 4.4 mm, NCHUZOOL 14952, Koto R., Tanai, Ube City, Yamaguchi Prefecture, N 34 ° 01 ' 08 ", E 131 ° 14 ' 46 ", coll. H. Yoshigou, 23 Jan. 2016. Mainland China: 2 males, cl 4.7 – 5.3 mm, 1 female, cl 4.8 mm, 1 damaged, cl 4.7 mm, NCHUZOOL 13342, Putian, Fujian, coll. H. - T. Shih, 7 Jul. 2004. Taiwan: 1 ovig. female, cl 5.4 mm, NCHUZOOL 13108, Sinshe, Taichung, coll. H. - T. Shih, 17 Apr. 2003; 1 female, cl 5.3 mm, NCHUZOOL 13109, Dounan, Yunlin, coll. H. - T. Shih, 28 Jul. 2006; 1 ovig. female, NCHUZOOL 13323, Guangfu, Hualien, coll. 7 Mar. 2009; 1 female, cl 3.3 mm, 1 damaged, cl 4.2 mm, NCHUZOOL 15178, Zuoying, Kaohsiung, coll. Oct. 2006; 2 damaged, NCHUZOOL 15177, Siaoliouciou, Pingtung, coll. 13 Nov. 2010. Native distribution: Mainland China and Taiwan (Cai 1996; Liang 2004). Remarks: Cai (1996) transferred C. davidi to the genus Neocaridina and treated it as a subspecies of N. denticulata. In the same publication, Cai (1996) redescribed Neocaridina denticulata sinensis based on specimens from Taihu, Jiangsu Province, China, the type locality, and highlighted that the characters separating N. d. sinensis from N. d. denticulata are the sexual dimorphism of the third pereiopods; the distinctly shorter appendix interna of the male second pleopods, and the relatively shorter rostrum. Liang (2002) described a new species, N. heteropoda, from Zhejiang Province, China and referred some of Cai’s (1996) N. d. sinensis to his new species. Liang (2002 2004) also considered that the characters separating N. d. denticulata (De Haan) and N. d. sinensis (Kemp) are not reliable, and treated N. d. sinensis from mainland China and Taiwan as a synonym of N. d. denticulata, referring the form introduced to Hawaii as N. heteropoda heteropoda. In response to this taxonomic action, Shih and Cai (2007) commented, “ … The validity of N. heteropoda Liang, 2002 is also doubtful as Liang (2004: 91) listed Caridina davidi Bouvier, 1904 as a synonym of N. heteropoda, which in turn, should make H. [sic. N.] heteropoda a junior synonym, if Liang’s (2004) conclusion is correct. ” Klotz et al. (2013) examined the co-type material of Caridina davidi Bouvier 1904 and tentatively assumed that N. heteropteran [sic. heteropoda] heteroptera [sic. heteropoda] Liang, 2002 and N. denticulata sinensis (Kemp, 1913 [sic. 1918]) are synonyms of N. davidi. Based on our current examination, N. davidi is closely related to N. denticulata, sharing a similar pear-shaped endopod of the male first pleopods, but it can be distinguished by the sexual dimorphism in the third pereiopods and the distinctly shorter appendix interna of the male second pleopods (Figs. 6, 7). The species is widely distributed in mainland China and Taiwan and has been introduced to Hawaii (Englund and Cai 1999), the main islands of Japan (see below), Germany (Klotz et al. 2013), Poland (Jabłońska et al. 2018), Hungary (Weiperth et al. 2019), Israel (Levitt-Barmats et al. 2019), and Canada (Toronto, based on GenBank sequence) (cf. Fig. 3). Nishino and Niwa (2004) first reported the occurrence of N. davidi (under the name Neocaridina denticulata sinensis) in Japan (Lake Biwa). Although N. denticulata was firstly recorded from Lake Biwa in 1915 (Kemp 1918), this indigenous shrimp had never been reported since then. In 2001, many individuals of another congeneric shrimp Neocaridina sp. were found in the lake (Nishino and Niwa 2004). Neocaridina davidi (as N. denticulata sinensis), presumed to be introduced from China or Korea as live bait for game fishing, has rapidly spread throughout Japan (Nishino 2017). Onuki and Fuke (2022) recently rediscovered the native species N. denticulata in Lake Biwa but found that in 11 of the 19 surveyed sites, the introduced species was dominant. Their results suggest that the native species has largely been replaced by the invasive species, and the native populations around Lake Biwa are in a critically threatened state. Fujita et al. (2011) also reported the occurrence of N. davidi (as N. d. sinensis) at Gono R. (Shimane) and Kako R. (Kakogawa, Hyogo). Fujita et al. (2011) found that N. denticulata has high genetic diversity in the sequences of ND 2 - tRNATrp + ND 5, with four distinct clades that roughly correspond to local populations of N. denticulata, but one clade was confirmed as N. davidi, and it is sympatric with N. denticulata in three rivers in western Japan. Neocaridina davidi has also been found in eastern Japan (Chiba) where no populations of N. denticulata were found (Toyota et al. 2014; Mitsugi et al. 2017; Mitsugi and Suzuki 2018). Mitsugi et al. (2017) reported the occurrence of N. davidi at Tomoe R., in Boso Peninsula, Chiba, eastern Japan. They found that their specimens are conspecific genetically with samples collected from Gono R. in Shimane Prefecture, Kako R. in Hyogo Prefecture, and Saba R. in Yamaguchi Prefecture. Mitsugi and Suzuki (2018) studied the life history of that population. Onuki (2021) investigated the distribution of N. davidi in relation to environmental parameters at Mama-shita Springs Park at Kunitachi, Tokyo.	en	Shih, Hsi-Te, Cai, Yixiong, Niwa, Nobuaki, Yoshigou, Hidenori, Nakahara, Yasuhiko (2024): Integrative Taxonomy Reveals Freshwater Shrimp Diversity (Decapoda: Atyidae: Neocaridina) from Kyushu and Southern Honshu of Japan, with a Discussion on Introduced Species. Zoological Studies 63 (18): 1-30, DOI: 10.6620/ZS.2024.63-18, URL: http://dx.doi.org/10.5281/zenodo.14702283
C9395B008B48FFCAF9A31458D2EE4E9B.taxon	description	Specimens examined: Japan: 1 male, cl 4.2 mm, NCHUZOOL 14940, 1 female, cl 5.5 mm, 1 ovig. female, cl 5.1 mm, non-eyed eggs 1.0 × 0.7 mm, NCHUZOOL 14941, Sugo R., Yumesaki River system, Himeji City, Hyogo Prefecture, N 34 ° 56 ' 31.9 ", E 134 ° 38 ' 19.0 '', coll. N. Niwa, 14 Aug. 2015; 1 female, cl 4.1 mm, NCHUZOOL 14954, Takahamagawa R., Takahamagawa system, Izumo City, Shimane Prefecture, N 35 ° 23 ' 33.3 ", E 132 ° 43 ' 37.1 ", coll. Y. Nakahara, 10 Mar. 2015; 1 female, cl 6.1 mm, NCHUZOOL 14965; Basen-gawa R., Go-no-gawa system, Miyoshi City, Hiroshima Prefecture, N 34 ° 46 ' 51 ", E 132 ° 54 ' 39 ", coll. H. Yoshigou, 28 Feb. 2016. 1 female, cl 4.7 mm, ZRC 2023.0217; Basen-gawa R., Go-no-gawa system, Miyoshi City, Hiroshima Prefecture, N 34 ° 46 ' 51 ", E 132 ° 54 ' 39 ", coll. H. Yoshigou, 28 Feb. 2016. Korea: 1 female, cl 5.0 mm, NCHUZOOL 14972, aquarium, coll. Jul. 2005. Mainland China: 1 female, cl 3.9 mm, NCHUZOOL 15169, Jiangle, Fujian, coll. H. - T. Shih, 5 Jul. 2004; 1 female, cl 4.3 mm, NCHUZOOL 15172, Nanping, Fujian, coll. H. - T. Shih, 5 Jul. 2004; 1 male, cl 4.1 mm, NCHUZOOL 15170, Yunnan, coll. H. - T. Shih, 5 Nov. 2002; 1 ovig. female, cl 6.2 mm, non-eyed eggs 0.9 × 0.7 mm, ZRC 2023.0218, Shilin, Yunnan, coll. Y. Cai, 11 Apr. 2005; 1 female, cl 6.0 mm, NCHUZOOL 15171, Kunming, Yunnan, coll. H. - T. Shih, 5 Nov. 2002. Native distribution: Korea and mainland China. Remarks: This species is morphologically very close to N. palmata, and currently we can only separate them based on subtle differences displayed by the available specimens (Fig. 10), e. g., the position of the appendix interna located at 0.35 times the length of the endopod (vs. 0.30 in N. palmata); the telson terminating in a prominent projection (vs. hardly discernible in N. palmata) and a broader scaphocerite (2.8 times as long as wide vs. 3.4 in N. palmata) (cf. Figs. 8, 9). Shih et al. (2017) assigned a specimen that they obtained from South Korea (aquarium dealer) to “ N. koreana ”. The specimen (NCHUZOOL 14972) was reexamined morphologically in the current study, but we are unable to confirm its identity morphologically as it is a female specimen. However, COI sequence data (Figs. 2, 3) firmly indicated that it should be re-assigned to N. aff. palmata instead. Kakui and Komai (2022) reported the first occurrence of the freshwater ectoparasitic platyhelminth Scutariella japonica from Yasuharu River, Sapporo, Hokkaido, Japan and discussed the identity of the host shrimps, a species of Neocaridina. Phylogenetic analyses using COI (Kakui and Komai 2022: fig. 5) showed that the host species is clustered with “ N. koreana ” identified by Shih et al. (2017) (see above), sister to N. palmata, and also close to two clades, “ N. davidi ” (types I and II, after Nagai and Imai 2021). The authors thus tentatively referred their shrimps to “ N. sp. aff. davidi ”. The Hokkaido COI sequences (LC 664097, LC 664098, LC 664099) were re-analyzed in our study and the results show that genetically they are conspecific with our material of “ N. aff. palmata ” (Fig. 3). The specimens from the same clade in Kakui and Komai (2022: fig. 5) would also be assigned to the same species, including specimens from Hyogo (AB 524970), Shimane (AB 524966, AB 524968), and Chiba (LC 664096), and Chinese material from Henan Province (MW 069628, MW 069631, MW 069644, MW 069650, MW 069652, MW 069653, MW 069657, MW 069661, MW 069670). Notably, based on one of the specimens, the drawings of the endopod of the male first pleopods, the appendix masculina of the male second pleopods, and the form of the dactylus and propodus of the male third pereiopods provided by Kakui and Komai (2022: fig. 3 E, F, H) clearly exhibit morphological characteristics consistent with N. davidi, despite the authors initially believing this specimen to be a young male. It is worth noting that our current study observed both N. aff. palmata and N. davidi living sympatrically in the streams at Hyogo, Himeji City and Shimane, Izumo City. The conflict between genetic and morphological findings suggests the possibility of interspecific hybridization (see “ DISCUSSION ”). Further investigation with both morphology and DNA testing would facilitate a taxonomic decision. The species is found in Fujian (Jiangle and Nanping) and Yunnan (Shilin and Kunming) in southern China, as well as the Korean Peninsula, so we presume that China and Korea are likely its native range. We have recorded its presence in several Japanese localities, including Hyogo, Shimane, Hiroshima, Chiba, and Hokkaido (Fig. 3). These localities are considered to represent one or more introductions, especially since the sites (Sites 2, 8 and 10 in Fig. 1) are also associated with other introduced species (Table 3).	en	Shih, Hsi-Te, Cai, Yixiong, Niwa, Nobuaki, Yoshigou, Hidenori, Nakahara, Yasuhiko (2024): Integrative Taxonomy Reveals Freshwater Shrimp Diversity (Decapoda: Atyidae: Neocaridina) from Kyushu and Southern Honshu of Japan, with a Discussion on Introduced Species. Zoological Studies 63 (18): 1-30, DOI: 10.6620/ZS.2024.63-18, URL: http://dx.doi.org/10.5281/zenodo.14702283
C9395B008B4CFFCBF9CB12B8D44D4DD8.taxon	description	Native distribution: This species is only distributed in Iki Island, Nagasaki Prefecture, western Japan (Shih et al. 2017). Remarks: This species was the second native species of Neocaridina discovered in the main islands of Japan; and its distribution is restricted to Iki Island, an offshore island in northern Kyushu (Shih et al. 2017). Fuke et al. (2021) questioned the validity of N. ikiensis, commenting that Shih et al. (2017) may not have adequately considered the genetic and morphological variations between their new species and the populations of N. denticulata in nearby regions, including what they referred to as “ N. denticulata ” from Fukue-jima Island, Goto, Nagasaki; Ishiki River, Kawatana, Nagasaki; Kuro River, Aso, Kumamota; and Machida R., Kokoneo, Oita. Their COI tree showed that N. ikiensis clustered together with several populations of their “ N. denticulata ”. By re-analyzing their sequences using longer lengths (Table 3), along with ours, the results (Fig. 3) indicate that N. ikiensis forms a sister clade with the Machida population. The samples collected from Kuro River and Ishiki River form one clade, which is sister to a clade composed of samples from the Goto Islands. The supported values of these two clades suggest that each clade may represent a separate species not previously recognized, here assigned as N. sp. 1 and N. sp. 2, from the Kuro / Ishiki River and from the Goto Islands, respectively. These two clades are distinctly differentiated from the taxa N. denticulata and N. aff. denticulata that our study recognizes based on both genetic and morphological data (cf. Fig. 3). The group formed by N. sp. 1, N. sp. 2, and N. aff. fukiensis is sister to another group comprising N. ikiensis and the previously mentioned Machida population (Fig. 3). Neocaridina aff. fukiensis is morphologically very distinct from N. denticulata (see Remarks under N. aff. fukiensis), and the Machida specimens may represent another separate species, named here as N. sp. 3, that is genetically similar to N. ikiensis. Since Fuke et al. (2021) did not provide morphological characters for the species they identified, we cannot compare these three potential unknown species to any of the known ones.	en	Shih, Hsi-Te, Cai, Yixiong, Niwa, Nobuaki, Yoshigou, Hidenori, Nakahara, Yasuhiko (2024): Integrative Taxonomy Reveals Freshwater Shrimp Diversity (Decapoda: Atyidae: Neocaridina) from Kyushu and Southern Honshu of Japan, with a Discussion on Introduced Species. Zoological Studies 63 (18): 1-30, DOI: 10.6620/ZS.2024.63-18, URL: http://dx.doi.org/10.5281/zenodo.14702283
C9395B008B4DFFCBFB551278D7774B5C.taxon	description	Specimens examined: Japan: 1 male, cl 6.6 mm, 1 male, cl 5.7 mm, 1 male, cl 6.0 mm, 10 males, cl 3.7 – 5.8 mm, NCHUZOOL 14946, 1 female, cl 7.7 mm, 1 female, cl 4.5 mm, NCHUZOOL 14947, Kaya R., Ashida River system, Fukuyama City, Hiroshima Prefecture, N 34 ° 36 ' 43 ", E 133 ° 15 ' 33 '', coll. H. Yoshigou, 17 Oct. 2015; 1 male, cl 4.5 mm, 1 male, cl 4.2 mm, 14 males, cl 3.8 – 5.7 mm, ZRC 2023.0219, Kaya R., Ashida River system, Fukuyama City, Hiroshima Prefecture, N 34 ° 36 ' 43 ", E 133 ° 15 ' 33 '', coll. H. Yoshigou, 1 Dec. 2016. Remarks: This species morphologically resembles Neocaridina fukiensis (Liang & Yan, 1978) including the form of its rostrum, which is elongated, reaching beyond the end of the antennular peduncle and with a slight upward curve distally; the telson terminates in a prominent projection; no sexual dimorphism in the third pereiopods; and the form of the appendix interna and the appendix masculina of the male second pleopods, with the appendix interna projecting out distinctly from the appendix masculina (Fig. 11). However, the endopod of the male first pleopods does not possess a distinct projection at its base (vs. with a distinct projection in N. fukiensis) and the fewer spines on the flexor margin of dactylus of the third pereiopods (6 – 7 vs. 9 – 10 in N. fukiensis) can be used to separate the two species easily. Fuke et al. (2021) assigned specimens collected from Miya River, Yufuin, Oita to “ Neocaridina sp. ” based on both morphological and molecular analyses. Upon re-analysis of their COI sequence data (LC 612372, LC 612374, LC 612376, LC 612378, LC 612379) in conjunction with our own data, the findings revealed that the Miya material clusters in a clade with our Fukuyama specimens, suggesting they are conspecific (Fig. 3). Despite these findings, a pending detailed morphological examination is necessary to confirm the identity of this clade, as it may represent an undescribed native species endemic to Japan. Additional geographic data are requisite to accurately establish its distributional range.	en	Shih, Hsi-Te, Cai, Yixiong, Niwa, Nobuaki, Yoshigou, Hidenori, Nakahara, Yasuhiko (2024): Integrative Taxonomy Reveals Freshwater Shrimp Diversity (Decapoda: Atyidae: Neocaridina) from Kyushu and Southern Honshu of Japan, with a Discussion on Introduced Species. Zoological Studies 63 (18): 1-30, DOI: 10.6620/ZS.2024.63-18, URL: http://dx.doi.org/10.5281/zenodo.14702283
C9395B008B4DFFC6F9ED169DD4EA4878.taxon	description	Specimens examined: Japan: 3 males, cl 3.5 – 4.6 mm, ZRC 2023.0221, Sugo R., Yumesaki R i v e r s y s t e m, H i m e j i C i t y, H y o g o P r e f e c t u r e, N 34 ° 56 ' 31.9 ", E 134 ° 38 ' 19.0 '', coll. N. Niwa, 14 Aug. 2015; 8 males, cl 4.6 – 5.5 mm, 15 females, cl 5.5 – 5.9 mm, ZRC 2023.0222, Oura upstream way (on Oura Dam), Izuharamachi-koura, Tsushima City, Nagasaki Prefecture, N 34 ° 14 ' 1.9 '', E 129 ° 17 ' 45.7 '', coll. H. Yoshigou, 15 Dec. 2016; 7 males, cl 5.2 – 6.0 mm, 10 females, cl 4.5 – 7.4 mm, ZRC 2023.0223, Takahama R., Mitsushimamachi-kechikou, Tsushima-shi, Tsushima City, Nagasaki Prefecture, N 34 ° 15 ' 32.4 '', E 129 ° 18 ' 47.5 '', coll. H. Yoshigou, 16 Dec. 2016. Remarks: Neocaridina aff. denticulata is similar to N. denticulata in the general appearance of the rostrum, the absence of sexual dimorphism in the third pereiopods, and the appendix masculina of the male second pleopods. However, it can be distinguished by its relatively shorter rostrum which reaches to or near to the end of the antennular peduncle (vs. mostly reaching beyond the antennular peduncle in N. denticulata); the exopod of the male first pleopods is 1.5 times as long as wide (vs. 1.2 times in N. denticulata); and the carpus of the first pereiopods is stouter (Fig. 13) (vs. slender in N. denticulata). Its distribution is confined to western Japan, encompassing western Honshu and Kyushu. The phylogenetic relationship with other species (Fig. 3) suggests that it is most probably a cryptic native species, which may have long been mistaken for N. denticulata.	en	Shih, Hsi-Te, Cai, Yixiong, Niwa, Nobuaki, Yoshigou, Hidenori, Nakahara, Yasuhiko (2024): Integrative Taxonomy Reveals Freshwater Shrimp Diversity (Decapoda: Atyidae: Neocaridina) from Kyushu and Southern Honshu of Japan, with a Discussion on Introduced Species. Zoological Studies 63 (18): 1-30, DOI: 10.6620/ZS.2024.63-18, URL: http://dx.doi.org/10.5281/zenodo.14702283
