Neocaridina koreana Kubo, 1938

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 : 22

Neocaridina koreana Kubo, 1938 ( Fig. 12 )

Specimens examined: Japan: 1 male, cl 4.1 mm, 3 males, cl 4.1–5.3 mm, NCHUZOOL 14964, 1 female, cl 4.1 mm, NCHUZOOL 14965, Go-no-gawa River system, Basen-gawa R., Miyoshi City, Hiroshima Prefecture, N34°46'51", E132°54'39", coll. H. Yoshigou, 28 Feb. 2016; 2 males, cl 5.0– 6.5 mm, ZRC 2023.0220, Basen-gawa R., Go-no-gawa system, Miyoshi City, Hiroshima Prefecture, N34°46'51", E132°54'39", coll. H. Yoshigou, 28 Feb. 2016.

Native distribution: Korea and probably China ( Cai 1996; Liang 2004).

Remarks: The original description of Neocaridina denticulata koreana Kubo, 1938 mentioned that “first cheliped rather short, with proportions against finger: palm 0.9, carpus 1.2, merus 1.4…” and “Second cheliped much longer than first, with proportions against finger: palm 0.9, merus 2.0.” “Endopodite of first pleopod pear-shaped, length about 1.7 times as long as breadth in male…” ( Kubo 1938: 81). Our specimens agree well with this description ( Fig. 12 ), but with a slightly more elongated endopod of the male first pleopods (1.85 times as long as wide) in adult males, which could be within the range of individual variation if a larger sample size were available.

Liang (2004) redescribed the species as having characteristic sexual dimorphism of the third pereiopods and transferred the taxon to the subspecies status under Neocaridina heteropoda (= N. davidi ), based on specimens from Zhejiang Province (Jinhua, Quxian). However, this reassignment could not be confirmed, as Kubo’s (1938) original description did not mention this character, and no topo-type specimens are available for comparison. Notably, our specimens do not exhibit any sexual dimorphism in the third pereiopods ( Fig. 12 ).

Park et al. (2019) reported the complete mitochondrial genome of Neocaridina koreana (as Neocaridina heteropoda koreana ) based on specimens collected from Geojedo, which is close to the type locality Huzan (Busan). Comparison of the available sequences shows that our specimens are conspecific with those from Geojedo ( Fig. 3 ). The Japanese record in our study represents the first confirmed record of the species to be introduced outside its natural range, Korea, and probably China ( Cai 1996; Liang 2004).

Figures

Fig. 12. Neocaridina koreana Kubo, 1938. (A) cephalothorax and cephalic appendages, lateral view; (B) 1st pereiopod; (C) 2nd pereiopod; (D) 3rd pereiopod; (E) the same, dactylus; (F) 5th pereiopod; (G) the same, dactylus; (H, I) male 1st pleopod. Scale bars: A = 2 mm; B–D, F = 0.5 mm; E, G–I = 0.2 mm (male, cl 4.1 mm, NCHUZOOL 14964, Basen-gawa R., Go-no-gawa system, Miyoshi City, Hiroshima Prefecture, N34°46'51", E132°54'39", coll. H. Yoshigou, 28 Feb. 2016).

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.