Neocaridina davidi (Bouvier, 1904)

Shih, Hsi-Te, Cai, Yixiong, Niwa, Nobuaki, Yoshigou, Hidenori & Nakahara, Yasuhiko, 2024, Fig. 4. A in Positive association between PTN polymorphisms and schizophrenia in Northeast Chinese Han population., Zoological Studies 63 (18), pp. 141-149 : 14-17

Neocaridina davidi (Bouvier, 1904) ( Figs. 6 , 7 )

Specimens examined: Japan: 6 males, cl 3.9–5.6 mm, ZRC 2023.0214, Sugo R., Yumesaki River system, Himeji City, Hyogo Prefecture, N34°56'31.9", E134°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, N34°01'08", E131°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 ND2-tRNATrp + ND5, 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.

Figures

Fig. 6. Neocaridina davidi (Bouvier, 1904). (A) cephalothorax and cephalic appendages, lateral view; (B) telson; (C) distal portion of telson; (D) preanal carina; (E) scaphocerite; (F, G) male 1st pleopod; (H, I) male 2nd pleopod; (J) uropodal diaeresis. Scale bars: A = 2 mm; B, D, F–J = 0.5 mm; C = 0.2 mm; E = 1 mm (A–H, J, male, cl 5.6 mm; I, male, cl 5.3 mm, ZRC 2023.0214, Sugo R., Yumesaki River system, Himeji City, Hyogo Prefecture, N34°56'31.9", E134°38'19.0'', coll. N. Niwa, 14 Aug. 2015).

Fig. 7. Neocaridina davidi (Bouvier, 1904). (A) 1st pereiopod; (B) 2nd pereiopod; (C) 3rd pereiopod; (D) the same, dactylus; (E) 5th pereiopod; (F) the same, dactylus. Scale bars: A, B, C, E = 0.5 mm; D, F = 0.2 mm (male, cl 5.6 mm, ZRC 2023.0214, Sugo R., Yumesaki River system, Himeji City, Hyogo Prefecture, N34°56'31.9", E134°38'19.0'', coll. N. Niwa, 14 Aug. 2015).

Fig. 3. Bayesian inference (BI) tree for species of the genus Neocaridina from the East Asia Arc and the related taxa from East Asia, based on the cytochrome c oxidase subunit I (COI) gene. Probability values at the nodes represent support values for BI and maximum likelihood (ML). Only support values> 50% are shown on the nodes. For haplotype names, see table 1. *, sequences downloaded from GenBank.