Biogeography 22. 9–15. Sep. 20, 2020

Morphological comparisons of Lefua costata (Teleostei: ), L. pleskei and L. nikkonis, with notes on morphological variations in L. costata introduced to Japan

Shotaro Ohgita 1 and Mizuki Matsunuma 2*

1 Graduate School of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan 2 Department of Environmental Management, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan

Abstract: Morphological comparisons of Lefua costata (Kessler, 1876) with related congeners, L. pleskei (Herzenstein in Warpachowski & Herzenstein, 1888) and L. nikkonis (Jordan & Fowler, 1903), resulted in a revision of diagnostic features for L. costata, including: a rhomboidal or triangular dark blotch in the middle of the caudal-fin base; a dark lateral stripe along the body in mature males; pre-dorsal vertebrae 16–18 (modally 17); abdominal vertebrae 18–22 (21); longitudinal scales 101–136; body depth 12.3–21.7% SL (mean 16.5% SL); body width 12.0–15.3% SL (13.8% SL); head depth 9.1–12.4% SL (10.9% SL); and interorbital width 7.3–9.6% SL (8.5% SL). Morphological differences between native populations of L. costata and introduced Japanese populations are also discussed.

Key words: Lefua nikkonis, Lefua pleskei, distribution, morphology, diagnosis

of pre-dorsal vertebrae (Naseka & Bogutskaya, 2004), and Introduction from L. nikkonis in having a greater number of longitudinal The Lefua Herzenstein, 1888 is characterized by scale rows and a smaller and narrower body (Nakajima & a rounded caudal fin, the anterior nostril with a long nasal Uchiyama, 2017). However, careful comparisons of L. costa- barbel, and the absence of a folding spine under the eyes and ta with the latter resulted in a revision of diagnostic postcleithrum and epural bones (Nichols, 1943; Sawada, 1982; features of the former. Since specimen-based description of L. Prokofiev, 2005; Ito et al., 2019). The genus is distributed costata was never given in the previous studies, a description throughout East Asia, including Mongolia, Russia, China, of L. costata is given, together with detailed comparisons with Korea and Japan (Kottelat, 2012; Hosoya, 2013). According congeners, and comments on intraspecific morphometric vari- to Kottelat (2013), Hosoya et al. (2018) and Ito et al. (2019), ations evident in introduced Japanese populations. the following seven nominal species are currently recognized Materials and Methods as valid: Lefua costata (Kessler, 1876), L. pleskei (Herzenstein in Warpachowski & Herzenstein, 1888), L. nikkonis (Jordan Counts and measurements followed Hubbs & Lagler (2004), & Fowler, 1903), L. echigonia Jordan & Richardson, 1907, L. except for vertebral counts which followed Hosoya (1983), sayu (Herre & Lin, 1936), L. torrentis Hosoya, Ito & Miyaza- with the following additions: pre-dorsal-fin trunk length - the ki, 2018 and L. tokaiensis Ito, Hosoya & Miyazaki, 2019. distance between the upper origin of the gill slit and the dor- Among the above species, L. costata is naturally distribut- sal-fin origin; and post-dorsal-fin length - the distance between ed (hereafter referred to as “native distribution”) in the Amur the dorsal-fin origin and mid-point of the caudal-fin base. River drainage, Korea [given the Japanese name “Hime-dojo” Barbel length was taken as the distance from the base to the by Mori (1928) in his checklist of Korean fishes] and north- extreme tip. Fin rays and vertebrae were counted from radio- eastern China, but is also known as an invasive species in graphs of the examined specimens (except for FAKU 51061, Japan (Naseka & Bogutskaya, 2004; Kottelat, 2012; Hosoya, FAKU 116365, FAKU 116366 and FKUN 31994–31998). The 2013; Nakajima & Uchiyama, 2017). Similar to L. pleskei and last two rays of the dorsal and anal fins were counted as a sin- L. nikkonis in having a rhomboidal or triangular dark blotch gle ray, each pair being associated with a single pterygiophore. in the middle of the caudal-fin base and a dark lateral stripe For morphometric comparisons, data from “narrow-body along the body in mature males (Ito et al., 2019; this study), form” L. costata specimens were excluded (see Table 1). L. costata can be distinguished from L. pleskei by the position Standard length is abbreviated SL. Institutional codes follow of the dorsal fin, snout length (or orbit diameter) and number Sabaj (2019). Identifications of L. costata, L. pleskei and L. −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− nikkonis are based on Naseka & Bogutskaya (2004), Shedko *Corresponding author: [email protected] et al. (2008), Hosoya (2013), Nakajima & Uchiyama (2017),

– 9 – Morphological comparisons of Lefua costata (Teleostei: Nemacheilidae), L. pleskei and L. nikkonis, with notes on morphological variations in L. costata introduced to Japan Hosoya et al. (2018) and Ito et al. (2019). male, KUN-P 52870 41.9 mm SL, female, KUN-P 52871 43.0 mm SL, male, Kurobe River, Hakanoki Nature Park, Nyuzen, Lefua costata (Kessler, 1876) Shimonikawa, Toyama Pref., 36°52’20”N, 137°32’35”E, 0.3 [Standard Japanese name: Hime-dojo] m depth, hand net, K. Mochizuki, 26 June 2019; robust-body (Figs. 1, 2, 4, 5, Tables 1, 2) form: KUN-P 48180, 67.3 mm SL, female, KUN-P 48181, Materials examined. Fifty eight specimens, 28.5–67.3 mm 62.5 mm SL, female, KUN-P 48182, 40.7 mm SL, male, SL. Japan: narrow-body form: HUMZ 228716, 34.8 mm SL, KUN-P 48183, 45.1 mm SL, male, Lake Midori, Hokuto, female, HUMZ 228717, 43.1 mm SL, male, HUMZ 228718, Yamanashi Pref., 35°51’29”N, 138°21’52”E, collection date 12 specimens, 28.5–52.8 mm SL, 2 males, 9 females and 1 unknown. North Korea: CAS-SU 25611, 3 specimens, 32.0– sex undetermined juvenile, Lake Midori, Hokuto, Yamanashi 43.8 mm SL, 2 males and 1 female, Seikoshin, J. Thompson, Prefecture (Pref.), 19 Mar. 2017; KUN-P 46649, 57.1 mm SL, 13 May 1911; CAS-SU 28151, 2 specimens, 37.5–39.3 mm female, KUN-P 46650, 47.0 mm SL, female, KUN-P 46651, SL, females, Nampo, Pyeongannam-do, D. Jordan, 1911; 49.2 mm SL, female, KUN-P 46652, 64.6 mm SL, female, CAS-SU 29531, 53.2 mm SL, female, Wonsan, J. Thompson; KUN-P 46653, 48.5 mm SL, female, KUN-P 46654, 39.5 CAS-SU 34741, 3 specimens, 42.8–48.8 mm SL, 2 males mm SL, female, KUN-P 46655, 42.8 mm SL, male, KUN-P and 1 female, Hoeryong, J. Thompson, 21 May 1911. South 48166, 41.3 mm SL, female, Kurobe River, Hakanoki Nature Korea: FAKU 51061, 41.0 mm SL, female, precise locality Park, Nyuzen, Shimonikawa, Toyama Pref., 3 Nov. 2011; unknown; FKUN 31994, 55.4 mm SL, female, FKUN 31995, KUN-P 46737, 53.6 mm SL, female, KUN-P 46738, 51.7 mm 48.1 mm SL, female, FKUN 31996, 42.8 mm SL, male, SL, female, KUN-P 46739, 46.6 mm SL, male, Lake Midori, FKUN 31997, 42.8 mm SL, male, FKUN 31998, 31.6 mm SL, Hokuto, Yamanashi Pref., 35°51’29”N, 138°21’52”E, 2018; male, Chodo, Goseng, Gangwon. China: FAKU 116365, 79.0 KUN-P 51148, 42.4 mm SL, male, Lake Midori, Hokuto, mm SL, female, FAKU 116366, 60.1 mm SL, female, precise Yamanashi Pref., 35°51’29”N, 138°21’52”E, hand net, K. locality unknown, 21 Jan. 1995. Mochizuki, 21 Aug. 2018; KUN-P 51153, 43.2 mm SL, male, Diagnosis. Lefua costata is distinguished from congeners KUN-P 51154, 38.2 mm SL, female, KUN-P 51164, 32.9 by the following combination of characters: rhomboidal or mm SL, female, KUN-P 51165, 36.8 mm SL, female, KUN-P triangular dark blotch in middle of caudal-fin base; dark lateral 51166, 31.6 mm SL, female, KUN-P 51167, 36.6 mm SL, stripe along body in mature males; pre-dorsal vertebrae 16–18 sex undetermined juvenile, KUN-P 51168, 32.1 mm SL, sex (modally 17); abdominal vertebrae 18–22 (21); longitudinal undetermined juvenile, KUN-P 51169, 29.3 mm SL, sex un- scales 101–136; body depth 12.3–21.7% SL (mean 16.5% SL); determined juvenile, Lake Midori, Hokuto, Yamanashi Pref., body width 12.0–15.3% SL (13.8% SL); head depth 9.1–12.4% 35°51’29”N, 138°21’52”E, 0.2 m depth, hand net, M. Fujita SL (10.9% SL); and interorbital width 7.3–9.6% SL (8.5% and Y. Yashima, 3 May 2019; KUN-P 52869, 45.3 mm SL, fe- SL).

Fig. 1. Fresh specimens of Lefua costata from Japan. (A) KUN-P 51153, 43.2 mm SL, male, Yamanashi; (B) KUN-P 52871, 43.0 mm SL, male, Toyama; (C) KUN-P 46737, 53.6 mm SL, female, Yamanashi; (D) KUN-P 52869, 45.3 mm SL, female, Toyama; (E) KUN-P 51168, 32.1 mm SL, sex unknown, Yamanashi; (F) KUN-P 51169, 29.3 mm SL, sex unknown, Yamanashi.

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Fig. 2. Preserved specimens of Lefua costata from native populations (A–D) and Japan, [“robust-body form” (E and F) and “narrow-body form” (G and H)]. (A) FAKU 116366, 60.1 mm SL, male, China; (B) FAKU 116365, 79.0 mm SL, female, China; (C) CAS-SU 29531, 53.2 mm SL, fe- male, North Korea; (D) FKUN 31998, 31.6 mm SL, male, South Korea; (E) KUN-P 48182, 40.7 mm SL, male, Yamanashi; (F) KUN-P 48181, 62.5 mm SL, female, Yamanashi; (G) KUN-P 51153, 43.2 mm SL, male, Yamanashi; (H) KUN-P 51165, 36.8 mm SL, female, Yamanashi.

Fig. 3. Preserved specimens of Lefua pleskei (A–D) and L. nikkonis (E–H) from Russia and Japan, respectively. (A) MCZ 32402, 1 of 5 speci- mens, 61.1 mm SL, male; (B) MCZ 32402, 1 of 5 specimens, 72.1 mm SL, female; (C) MCZ 34071, 1 of 3 specimens, 56.9 mm SL, female; (D) HUMZ 221085, 42.4 mm SL, female; (E) HUMZ 135688, 46.6 mm SL, male; (F) HUMZ 135691, 58.3 mm SL, female; (G) HUMZ 87793, 37.3 mm SL, female; (H) HUMZ 87796, 28.6 mm SL, female.

Description. Meristic and morphometric data shown in diameter 1.3–2.6 (mean 1.8) times snout length. Snout short, Tables 1 and 2. Body elongate, relatively slender, deepening rounded. Mouth small, inferior, cleft almost horizontal. Both slightly from occiput to dorsal-fin origin, slightly compressed lips fleshy, smooth; upper lip without median incision; lower laterally from posterior dorsal-fin base to anterior dorsal lip with median notch ventrally. Two pairs of rostral barbels keel (Figs. 1, 2). Head depressed. Eye moderately large, its and one pair of mandibular barbels; tip of inner rostral barbel

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Fig. 4. Relationships of (A) snout length/orbit diameter ratios and (B) Fig. 5. Relationships of (A) body width and (B) body depth (as % of pre-dorsal-fin trunk length/post-dorsal-fin length ratios to stand- standard length) to standard length (mm) in Lefua costata [native ard length (mm) in Lefua costata [native distribution (triangles) distribution (triangles), and “robust-body form” (squares) and and “robust-body form” from Japan (squares)], and L. pleskei “narrow-body form” (circles) from Japan]. (diamonds). reaching anterior nostril or slightly beyond posterior nostril distinct dark lateral stripe from snout to middle of caudal fin when depressed backwards; tip of outer rostral barbel reaching (Fig. 1A, B); females with a poorly defined dark lateral stripe to or slightly beyond middle of eye when depressed back- from behind opercle to caudal-fin base (Fig. 1C, D). All fins wards; mandibular barbel longest, its tip reaching posterior semi-translucent brown; dorsal and caudal-fin rays scattered margin of eye when depressed backwards. Nostrils separate; with poorly defined small dark blotches; caudal-fin base with anterior nostril with long nasal barbel reaching to or slightly small dark blotch in females and juveniles. Barbels light gray beyond anterior margin of eye when depressed backwards; or light brown. posterior nostril opening larger than that of anterior nostril. Coloration of preserved specimens. Based on all examined Dorsal and ventral keels present on caudal peduncle; dorsal specimens (Fig. 2). Head, body and fins generally pale gray keel originating just behind end of dorsal-fin base; ventral to brown. Longitudinal stripe along body present but obscure keel close to end of anal-fin base. Caudal peduncle short; its in both males and females. Caudal-fin base with small dark length 1.1–2.0 (1.6) times its depth (including dorsal and ven- blotch. tral keels). Scales cycloid, embedded under skin. Lateral line Distribution. The species is naturally distributed in Mon- absent. Dorsal fin small, rounded, originating closer to cau- golia, northeastern China and the Korean Peninsula (Naseka dal-fin base than to snout tip. Pectoral fin set horizontally, with & Bogutskaya, 2004; Shedko et al., 2008; Kottelat, 2012; this rounded contour. Pelvic fin small, rounded, its origin anterior study), and has also been introduced to Japan (recorded from to a vertical through dorsal-fin origin. Anal fin small, round- Toyama, Yamanashi, Nagano, Shizuoka and Wakayama pre- ed. Membranes between rays of all fins weakly incised. Anus fectures) (Hosoya, 2013, 2015; Nakajima & Uchiyama, 2017; slightly anterior to anal-fin origin. this study). The history of introductions, distribution and hab- Fresh coloration. Based on photographs of fresh spec- itats of Japanese populations have been reviewed in detail by imens from Japan (Fig. 1). Head and body generally light Nakajima & Uchiyama (2017). gray or light brown, whitish ventrally; mature males with a Remarks. Although Berg (1949) regarded L. pleskei as a

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Table 1. Meristics and morphometrics of Lefua costata, L. pleskei and L. nikkonis. L. costata L. pleskei L. nikkonis Locality Korea and Japan Russia Japan China Narrow-body form Robust-body form No. of specimens 37 4 17 Modes 6 Modes 10 Modes Dorsal-fin rays iii + 6 or 7 iii + 6 or 7 iii + 6 or 7 iii + 7 iii + 6 or 7 iii + 7 iii + 6 or 7 iii + 7 Pectoral-fin rays i + 10 or 11 i + 10 or 11 i + 10 or 11 i + 10 i + 10 i + 10 i + 10 or 11 i + 10 Anal-fin rays iii + 5 or 6 iii + 5 or 6 iii + 5 or 6 iii + 6 iii + 5 or 6 iii + 6 iii + 5 or 6 iii + 6 Pelvic-fin rays ii + 5–7 ii + 5–7 ii + 6 or 7 ii + 6 ii + 5–7 ii + 7 ii + 5–7 ii + 5 Longitudinal scales 101–136 102–131 101–127 112 100–114 114 60–92 71 Abdominal vertebrae 18–21 20–22 18–21 21 22–24 23 20–22 20 Caudal vertebrae 17–20 17–19 18–21 19 16–19 17 15–17 17 Pre-dorsal-fin vertebrae 17 or 18 16–18 16–18 17 18 or 19 18 16–18 16 Total vertebrae 37–40 37–40 35–40 39 39–41 40 35–39 37 SL (mm) 28.5–64.6 40.7–67.3 31.6–79.0 Means* 42.4–72.1 Means 28.6–58.3 Means Head length (% SL) 19.5–25.3 20.2–22.9 20.6–25.5 23.2 21.9–23.7 22.7 23.5–29.4 26.0 Head depth 9.0–11.9 10.4–10.8 9.1–12.4 10.9 10.1–12.0 10.8 10.8–15.7 13.2 Body width 9.5–12.8 13.9–14.9 12.0–15.3 13.8 12.4–14.5 13.8 14.9–19.6 16.9 Body depth 8.4–14.8 15.9–16.3 12.3–21.7 16.5 13.9–16.0 15.2 14.3–20.3 18.2 Caudal-peduncle length 13.1–17.8 15.5–17.2 13.6–16.9 15.6 13.4–17.3 12.8–16.8 15.0 Caudal-peduncle depth 7.1–11.3 10.0–12.3 9.7–13.4 11.4 8.7–11.6 10.4 10.8–15.1 13.2 Pre-dorsal-fin length 55.1–65.7 58.5–61.9 58.1–63.9 60.3 57.7–63.9 60.6 59.4–65.7 62.6 Pre-anal-fin length 74.8–81.7 75.0–79.8 72.4–83.5 77.2 77.3–81.1 78.7 77.3–81.1 78.7 Pre-pelvic-fin length 51.8–61.2 53.7–58.5 52.1–60.8 56.8 55.1–59.1 57.6 56.4–62.6 60.1 Lower origin of pectoral-fin 31.2–39.0 34.6–38.0 32.0–39.3 35.7 35.5–39.7 36.9 30.6–38.3 34.8 to pelvic-fin origin Dorsal-fin height 7.0–11.9 9.1–11.1 7.7–10.3 9.7 8.6–12.1 10.2 7.7–15.0 11.4 Dorsal-fin base length 6.9–10.3 9.0–11.1 8.1–11.6 9.8 8.5–9.9 9.5 9.4–12.6 10.6 Anal-fin height 6.3–11.2 8.2–9.5 6.6–12.8 9.2 7.8–11.1 9.3 7.0–11.0 9.5 Anal-fin base length 5.6–8.4 7.3–9.1 5.9–9.1 7.8 6.6–8.4 7.6 6.9–9.2 8.2 Pectoral-fin length 11.5–17.2 13.0–16.0 13.3–18.8 15.9 13.7–16.5 15.3 13.1–18.6 15.6 Pectoral-fin base length 2.1–4.4 2.9–3.9 3.1–4.5 3.7 3.2–4.1 3.6 3.5–4.4 4.0 Snout length 5.7–7.6 7.3–7.9 6.4–8.7 7.8 6.2–7.2 6.7 8.1–9.2 8.6 Upper-jaw length 3.6–5.2 4.8–5.4 4.0–5.0 4.7 4.3–4.7 4.5 3.3–5.6 4.0 Orbit diameter 2.8–5.0 3.3–4.0 3.3–5.0 3.9 2.9–4.2 3.7 3.2–5.1 4.0 Interorbital width 6.2–7.8 7.3–8.5 7.4–9.6 8.5 9.0–10.0 9.5 9.1–11.9 10.3 Nasal barbel length 3.4–7.3 4.5–5.3 3.7–5.9 4.7 4.1–6.1 5.3 4.4–7.9 5.9 Inner rostral barbel length 3.5–6.9 5.9–6.4 4.2–6.7 5.5 4.2–6.5 5.4 2.8–6.4 4.9 Outer rostral barbel length 4.6–7.3 6.2–7.0 4.9–8.9 6.2 5.3–7.5 6.5 5.0–7.4 6.3 Mandibular barbel length 5.6–9.0 6.1–7.1 5.3–9.6 6.6 6.8–8.5 7.6 6.5–8.7 7.7 Pre-dorsal-fin trunk length 37.8–45.6 41.2–44.7 40.2–49.7 42.3 42.1–45.8 44.2 38.1–44.8 41.4 Post-dorsal-fin length 36.2–44.5 41.8–45.6 39.5–45.3 43.0 38.0–42.1 40.9 38.6–44.0 41.1 *excluding "narrow-body form" specimens junior synonym of L. costata, the former is now regarded as Naseka & Bogutskaya (2004) considered that L. costata a valid species (see Naseka & Bogutskaya, 2004; Kottelat, could be distinguished from L. pleskei (co-occurring in the 2012), several studies referring to distinct genetic divergence Sungari River, China), due to a relatively shorter snout (or between L. pleskei and some congeners, including Sakai et al. larger eye) in the former (snout length/orbit diameter ratio ca. (2003), Mihara et al. (2005), Shedko et al. (2008) and Ooyagi 1.8, c.f. ca. 2.0–2.2 in the latter). However, such a difference et al. (2018). We tentatively regarded L. costata and L. pleskei between the two species was not found here (ratio 1.4–2.6 as valid species, following Naseka & Bogutskaya (2004), in L. costata vs. 1.5–2.2 in L. pleskei; Fig. 4A). The snout Shedko et al. (2008), Hosoya (2013), and Nakajima & Uchi- length/orbit diameter ratio probably changes with growth in yama (2017). Within the genus, L. costata is most similar cor- both species. Naseka & Bogutskaya (2004) also stated that L. rect to L. pleskei and L. nikkonis in overall body appearance costata differed from L. pleskei in pre-dorsal-fin trunk length and coloration, mature males sharing a dark lateral stripe on (slightly less than post-dorsal-fin length, with the dorsal-fin the body (Figs. 1, 3). situated slightly posterior to the trunk midpoint in L. costata;

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Table 2. Frequency of meristic values for selected characters of Lefua costata, L. pleskei and L. nikkonis. Abdominal vertebrae Caudal vertebrae 18 19 20 21 22 23 24 15 16 17 18 19 20 21 22 L. costata 2 12 14 21 1 1 9 16 16 6 1 L. pleskei 2 3 1 1 3 1 1 L. nikkonis 5 3 1 1 4 4 Pre-dorsal-fin vertebrae Total vertebrae 16 17 18 19 35 36 37 38 39 40 41 L. costata 4 36 10 1 4 18 23 4 L. pleskei 5 1 1 3 26 L. nikkonis 6 2 1 1 1 6 1 Longitudinal scales 60 61 62 — 65 — 70 71 — 77 — 88 — 91 — 100 101 102 103 104 105 106 107 L. costata 4 4 2 2 1 3 2 L. pleskei 1 L. nikkonis 1 1 1 1 2 3 1 1 Longitudinal scales (continued) 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 — 131 — 136 L. costata 1 1 3 4 1 2 1 2 3 4 1 1 1 1 2 3 1 2 1 1 L. pleskei 2 1 2 L. nikkonis pre-dorsal-fin length slightly longer than or subequal to post- fishing bait and the aquarium trade (Hosoya, 2013; Nakajima dorsal-fin length in L. pleskei). However, the pre-dorsal-fin & Uchiyama, 2017). Initially misidentified as L. nikkonis, L. trunk length/post-dorsal-fin length ratios of the two species costata was first reported from Toyama Prefecture (Inamura overlapped in the present comparison (Fig. 4B). et al., 1993). Sakai et al. (2003) also identified specimens of As stated by Naseka & Bogutskaya (2004), L. costata L. costata from Toyama, Yamanashi and Nagano prefectures can be distinguished from L. pleskei by the slightly fewer as L. nikkonis, but their Japanese samples were later correctly pre-dorsal vertebrae 16–18 (modally 17), compared with 18 identified as L. costata by Mihara et al. (2005). Currently, L. or 19 (18) in the latter (Table 2). In addition, L. costata is also costata is known from many localities in Japan (see Distribu- distinguished from L. pleskei by having slightly fewer ab- tion). dominal vertebrae 18–22 (modally 21), compared with 22–24 Distinct proportional differences were recognized between (23) in the latter (Table 2). Although Naseka & Bogutskaya the native populations (Fig. 2A–D) and introduced Japanese (2004) used only female specimens for comparisons of the populations (“narrow-body form”; Fig. 2G–H) of L. costa- two species to avoid problems of sexual dimorphism, sexual ta, including body width (12.0–15.3% SL in the former vs. differences in meristic or morphometric characters were not 9.5–12.8% SL in the latter) and body depth (12.3–21.7% SL apparent in either species (this study). in the former vs. 8.4–14.8% SL in the latter) (Fig. 5). In recent Lefua nikkonis has been described as having fewer longi- times, L. costata numbers have increased and the species is tudinal scales, and a slightly deeper robust body compared now dominant in Lake Midori (Ohama et al., 2013). Accord- with L. costata [Hosoya, 2013, 2015 (as L. c. nikkonis); ingly, such changes in body shape in introduced Japanese Nakajima & Uchiyama, 2017]. The present study confirmed populations may have resulted from high population densities such differences between the two species: longitudinal scales in limited habitats and resulting reduction in food resources, (60–92 in the former vs. 101–136 in the latter), body depth or from other environmental factors. In contrast, “robust-body [14.3–20.3% SL (mean 18.2% SL) vs. 12.3–21.7% SL (16.5% form” specimens from Lake Midori, Yamanashi Prefecture, SL)] and width [14.9–19.6% SL (16.9% SL) vs. 12.0–15.3% Japan had similar body proportions to the native populations SL (13.8% SL)], the body depth difference being obvious in (Table 1; Fig. 5). Although the collection dates of the former specimens

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1 female, Avvakumovka River, Russia, 20 July 1927. Lefua known to occur in freshwaters, mangroves and estuaries. nikkonis (10 specimens, 28.6–58.3 mm SL): FAKU 115888, Raffles Bull. Zool., 27: 1–663. 41.4 mm SL, female, Tarumae, Tomakomai, Hokkaido, Japan, Mihara, M., Sakai, T., Nakao, K., Martins, L. O., Hosoya, K. 6 or 7 Oct. 1979; HUMZ 87791, 43.1 mm SL, female, HUMZ & Miyazaki, J., 2005. Phylogeography of loaches of the 87792, 36.8 mm SL, male, HUMZ 87793, 37.8 mm SL, fe- genus Lefua (Balitoridae, ) inferred from mi- male, HUMZ 87794, 30.9 mm SL, female, HUMZ 87795, tochondrial DNA sequences. Zool. Sci., 22: 157–168. 30.5 mm SL, female, HUMZ 87796, 28.6 mm SL, female, Mori, T., 1928. A catalogue of the fishes of Korea. J. Pan-Pa- Rurumappu River, Chitose River system, near Eniwa-Isikari cific Res. Inst., 3: 3–8. Sub-Prefecture Office, Hokkaido, Japan, 24 July 1980; HUMZ Nakajima, J. & Uchiyama, R., 2017. Loaches of Japan—Nat- 135688, 46.6 mm SL, male, HUMZ 135691, 56.8 mm SL, ural History and Culture. Yama-Kei Publishers, Tokyo. (in female, creek at Ōno, Hokkaido, Japan, 2 May 1995; HUMZ Japanese) 204658, 49.2 mm SL, male, Nanbujinnya, Oshamambe, Hok- Naseka, A. M. & Bogutskaya, N. G., 2004. Contribution to kaido, Japan, 29 Apr. 2009. and nomenclature of freshwater fishes of the Amur drainage area and the Far East (Pisces, Osteichthyes). Acknowledgements Zoosyst. Ross., 12: 279–290. We are especially grateful to D. Catania (CAS), Y. Kai Nichols, J. T., 1943. The Fresh-water Fishes of China. Ameri- (FAKU), F. Tashiro (HUMZ) and A. Williston (MCZ) for can Museum of Natural History, New York. providing opportunities to examine specimens, and to T. Ito Ohama, H., Kaji, N. & Aoyagi, T., 2013. Distribution of Lefua (Tokushima Prefectural Museum) for advice with counts and costata in Yamanashi Prefecture, Japan. Rep. Yamanashi measurements. We also thank all students of KUN for cura- Pref. Fish. Tec. Cent., 40: 30–33. (in Japanese) torial assistance, and G. Hardy (Ngunguru, New Zealand) for Ooyagi, A., Mokodongan, D. F., Montenegro, J., Mandagi, I. reading the manuscript and providing help with English. F., Koizumi, N., Machida, Y., Inomata, N., Shedko, S. V., Hutama, A. A., Hadiaty, R. K. & Yamahira, K., 2018. Phy- References logeography of the eight-barbel loach Lefua nikkonis (Cyp- Hosoya, K., 1983. Geographic variation of number of verte- riniformes: Nemacheilidae): how important were straits in brae in Squalidus. Freshw. Fish., 9: 43–48. (in Japanese) northern Japan as biogeographical barriers?. Ichthyol. Res., Hosoya, K., 2013. Cobitidae. In: Nakabo, T. (Ed.), Fishes of 65: 115–126. Japan with Pictorial Keys to the Species, Third Edition: Prokofiev, A. M., 2005. Osteology of Oreonectes platyceph- 328–334, 1819–1822. Tokai University Press, Hadano (in alus Günther, 1868 (Balitoridae: Nemacheilinae) with Japanese) remarks on the genus composition and its phylogenetic re- Hosoya, K., 2015. Lefua costata nikkonis (Jordan and Fowler, lations. J. Ichthyol., 45: 429–443. 1903). In: Hosoya, K. (Ed.), Freshwater Fishes of Japan: Sakai, T., Mihara, M., Shitara, H., Yonekawa, H., Hosoya, 188–189 Yama-Kei Publishers, Tokyo. (in Japanese) K. & Miyazaki, J., 2003. Phylogenetic relationships and Hosoya, K., Ito, T. & Miyazaki, J., 2018. Lefua torrentis, intraspecific variations of loaches of the genus Lefua (Bali- a new species of loach from western Japan (Teleostei: toridae, Cypriniformes). Zool. Sci., 20: 501–514. Nemacheilidae). Ichthyol. Explor. Freshw., 28: 193–201. Sabaj, M. H., 2019. Standard symbolic codes for institutional Hubbs, C. L. & Lagler, K. F., 2004. Fishes of the Great Lakes resource collections in herpetology and ichthyology: Region. Revised Edition. University of Michigan Press, An Online Reference. Version 7.1 (21 March 2019). Bloomfield Hills. Electronically accessible at http://www.asih.org, American Inamura, O., Kitamura, N. & Arai, Y., 1999. The record of Society of Ichthyologists and Herpetologists, Washington, Lefua nikkonis at the Kurobe River in Toyama Prefecture. DC. Bull. Toyama Sci. Mus., 22: 147–148. (in Japanese) Sawada, Y., 1982. Phylogeny and zoogeography of the super- Ito, T., Hosoya, K. & Miyazaki, J., 2019. Lefua tokaiensis, a family Cobitoidea (Cyprinoidei, Cypriniformes). Mem. Fac. new species of nemacheilid loach from central Japan (Tele- Fish. Hokkaido Univ., 28: 65–223. ostei: Nemacheilidae). Ichthyol. Res., 66: 479–487. Shedko, S. V., Miroshnichenko, I. L. & Nemkova, G. A., 2008. Kottelat, M., 2012. Conspectus cobitidum: an inventory of the On the systematics and phylogeography of eight-barbel loaches of the world (Teleostei: Cypriniformes: Cobitoidei). loaches of the genus Lefua (Cobitoidea: Nemacheilidae): Raffles Bull. Zool., 26: 1–199. mtDNA typing of L. pleskei. Russ. J. Genet., 44: 817–825. Kottelat, M., 2013. The fishes of the inland waters of South- east Asia: a catalogue and core bibliography of the fishes (Received January 31, 2020; Accepted June 30, 2020)

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