Lefua nishimurai Katayama, 2024

Katayama, Yuta & Sawada, Naoto, 2024, Integrative taxonomy revealed a new species of Lefua (Teleostei, Nemacheilidae) from Fukui Prefecture, Japan, Evolutionary Systematics 8 (2), pp. 247-260 : 247-260

Lefua nishimurai Katayama sp. nov.

Table 4 , Figs 5 E , 6 E , 7 , 8 , 9 New Standard Japanese name: Reihoku-nagare-hotoke-dojyô

Lefua torrentis : Natural Environment Division, Department of Safety and Environment, Fukui Prefecture 2016: 110 (part); Nakajima et al. 2021: 35, fig. 1; Katayama 2021: 54, fig. 5.

Material examined.

Holotype. • LBM 1210059189 ; 51.2 mm SL; collected from Kuzuryu River system , Fukui, Fukui Prefecture, Japan; 36.0621 ° N, 136.1304 ° E; on 6 Sep. 2021 by Yuta Katayama.

Paratypes. Eighteen specimens collected from Kuzuryu River system in Fukui Prefecture, Japan by Y. Katayama. • LBM 1210059177 ; 44.4 mm SL from Echizen on 17 Jul. 2021 ; • LBM 1210059178 , 58.8 mm SL ; • LBM 1210059179 , 44.4 mm SL ; • LBM 1210059180 , 40.0 mm SL from Fukui on 18 Jul. 2021 ; • LBM 1210059181 , 61.5 mm SL ; • LBM 1210059182 , 52.8 mm SL ; • LBM 1210059183 , 44.2 mm SL ; • LBM 1210059184 , 49.6 mm SL from Echizen on 17 Jul. 2021 ; • LBM 1210059185 , 59.9 mm SL ; • LBM 1210059186 , 43.0 mm SL ; • LBM 1210059187 , 44.5 mm SL from Echizen on 6 Sep. 2021 ; • LBM 1210059188 , 55.0 mm SL ; • LBM 1210059190 , 57.0 mm SL ; • LBM 1210059191 , 44.5 mm SL ; • LBM 1210059192 , 63.2 mm SL ; • LBM 1210059193 , 48.7 mm SL ; • LBM 1210059194 , 62.9 mm SL from Fukui on 6 Sep. 2021 ; • LBM 1210059195 , 57.4 mm SL from Echizen on 13 Nov. 2021 .

Additional specimens.

Six specimens collected from Kuzuryu River system in Fukui Prefecture, Japan by Y. Katayama. • FAKU 211455 , 41.5 mm SL ; • FAKU 211456 , 61.3 mm SL ; • FAKU 211457 , 56.1 mm SL from Echizen on 1 Oct. 2023 ; • FAKU 211458 , 51.9 mm SL ; • FAKU 211459 , 47.3 mm SL ; • FAKU 211460 , 44.5 mm SL from Fukui on 1 Oct. 2023 .

Diagnosis.

Lefua nishimurai sp. nov. can distinguished from all other species of Lefua by combing following features: absence of rhomboid or triangular dark blotches on middle of caudal fin base; absence of black longitudinal stripe on both body sides in mature males; absence of dusky cross bars on dorsal area of body; absence of dusky bar beside dorsal fin base; eyes located dorsally on head; narrow conspicuous longitudinal mark between base of outer rostral barbel and eye; small dorsal fin; small orbit diameter (6.3–11.2 % of head length); small value of interorbital width relative to body width (28.1–39.4 %); dark spots dorsally and ventrally on caudal fin base; small dark brown spots from snout to caudal peduncle; small dark spots on dorsal and caudal fins (approximately same size as eyes).

Description.

Measurements and counts listed in Table 4 . Body elongated and cylindrical, slightly longitudinally flattened, and caudal peduncle laterally flattened. Dorsal and ventral sides of caudal peduncle keeled, and depth of caudal peduncle, including keel, about same as body depth. Head small (less than one-fourth of SL), slightly dorsoventrally compressed. Snout relatively long, comprising 38.7 % in holotype (32.3–46.4 % in paratypes and additional specimens) of head length, with tip rounded in dorsal view. Eyes positioned on dorsolateral surface of head (Figs 6 – 8 ), very small. Interorbital width comprises 51.5 % (42.9–59.0 %) of body width, and orbit diameter comprises 6.6 % (6.3–11.2 %) of head length (Figs 6 – 8 ). Mouth subterminal; small and inferior, slightly arched. Upper and lower lips fleshly and smooth (Figs 7 , 8 ). No median incision in upper lip. One median notch in lower lip. Three pairs of barbels, two pairs of rostral barbels, and one pair of maxillary barbels. Inner rostral barbel relatively short, reaching to or slightly past vertical through anterior margin of eye when extended horizontally, outer rostral barbel longest, slightly past vertical through posterior margin of eye when extended horizontally, maxillary barbel past vertical through posterior margin of eye when extended horizontally. Nostrils separated from each other, anterior nostril formed as 1 long nasal barbel, posterior nostril larger than anterior nostril, anterior nostril at anterior side of 1 nasal barbel, close to base. Nasal barbel extended horizontally past posterior border of eye. Dorsal and ventral keels on caudal peduncle; dorsal keel starting slightly posterior to extremity of dorsal fin base, ventral keel starting posterior to extremity of anal fin base. Length of caudal peduncle 1.0 (1.0–1.3) times depth of caudal peduncle (depth including keel). Scales embedded on body. Lateral line absent. Dorsal fin rounded. Origins of dorsal fin nearer to caudal fin base than to tip of snout. Pectoral fin horizontal. Pelvic fin anterior to dorsal fin. Anal fin rounded. Anus positioned slightly anterior to anal fin. Caudal fin rounded. Dorsal fin with 4 (3–4) simple and 5 (5–6) branched rays. Second branched ray longest. Anal fin with 4 (3–4) simple and 5 (5–6) branched rays. Pectoral fin with 1 simple and 11 (10–11) branched rays. Second branched ray longest. Pelvic fin with 1 simple and 5 branched rays. No pelvic axillary lobe. Caudal fin with 2 (1–2) simple, 6 (5–7) branched, 7 (6–7) branched and 1 (1–2) simple principal rays. Total vertebrae 41 (39–43); abdominal vertebrae 23 (21–23), caudal vertebrae 18 (16–21).

Coloration.

Live specimens, body and head light brown with strong yellowish tinge except for whitish gray ventral surface (Fig. 7 ). One narrow conspicuous black stripe between base of outer rostral barbel and eye (Fig. 8 ). Entire body from snout to caudal peduncle scattered dark brown spots. Largest of spots slightly larger than orbit diameter. Both lips white, with one pair of small brown spots inside lower lip tissue (Fig. 8 ). All fins pale to translucent. Pectoral fin yellowish brown, with dark spots at the base and anterior half. Dorsal fin yellowish brown with dark spots from base to middle. Anal fin with a few dark spots on basal half (sometimes absent). No spots on pelvic fin. Caudal fin yellowish brown with dark spots from base to a little closer to tip of middle, but translucent and without spots on margins. Dorsal and ventral surfaces of caudal fin base with dark brown spots (rarely absent) (Figs 8 , 9 ). No obscure dark band in skin of caudal fin base (rarely present) (Figs 5 , 7 , 9 ).

Etymology.

The specific name is dedicated to Toshiaki Nishimura, who first morphologically distinguished this new species.

Distribution.

This new species was recorded in the Kuzuryu River drainage system of the Reihoku Region in Fukui Prefecture, central Japan ( Katayama 2021; Fig. 1 ).

Habitat and biology.

Lefua nishimurai sp. nov. inhabits small mountain streams surrounded by natural or planted forests, and prefers sandy or gravelly bottoms (Fig. 10 ). The new species usually hides under rocks and stones at the river edge or under sediments, such as fallen leaves. It has been estimated that spawning of this species occurs from late April to mid-June ( Katayama 2021).

Remarks.

The new species is similar to L. torrentis and L. tokaiensis with a narrow conspicuous longitudinal mark between the base of the outer rostral barbel and eye. However, L. nishimurai sp. nov. can be distinguished from L. torrentis based on the following characteristics: eyes located dorsally on head (more lateral in L. torrentis ), small orbit diameter (larger in L. torrentis ), dark spots on the caudal fin base (rarely absent in the new species; usually absent in L. torrentis ), small dark spots on dorsal and caudal fins, and distinct dark brown spots scattered over the body (rarely absent in the new species; entirely absent in L. torrentis ). The new species and L. tokaiensis can also be discriminated by eyes located dorsally on the head (more lateral in L. tokaiensis ), small orbit diameter (larger in L. tokaiensis ), dark spots dorsally and ventrally on the caudal fin base (rarely absent in the new species; entirely absent in L. tokaiensis ), distinct dark brown spots scattered over the body (rarely absent in the new species; entirely absent in L. tokaiensis ), and fan-shaped caudal fin of L. nishimurai (squared-off apex in L. tokaiensis ). Both the new species and L. torrentis inhabiting Wakayama Prefecture, and Shikoku and Awaji Islands possess dark brown spots of varying sizes on the body, dorsal side, and caudal peduncle ( Hosoya et al. 2018). However, L. nishimurai sp. nov. represents smaller spots than the other species on the entire body and dorsal surfaces as well as on the dorsal and caudal fins (approximately the same size as the eyes) (Fig. 5 ).

Comparative material examined.

Lefua torrentis , 46 specimens (33.2–66.9 mm SL). Holotype: • KUN-P 45408; 44.9 mm SL collected from Yura River system, Kasuga, Tanba , Hyogo; • FAKU 211461–211464 , 4 specimens, 33.2–49.4 mm SL from Arida River system, Aridagawa , Wakayama; • FAKU 211465–211468 , 4 specimens, 43.4–55.5 mm SL, from Hidaka River system, Hidaka , Wakayama; • FAKU 211469–211477 , 9 specimens, 38.4–49.9 mm SL from Orino River system, Kitanada , Tokushima; • FAKU 211478–211480 , 3 specimens, 42.9–55.5 mm SL from Yoshino River system, Gomyo , Kagawa; • FAKU 211481–211484 , 4 specimens, 40.4–63.6 mm SL from Sumoto River system, Ayuya , Hyogo; • FAKU 211485–211490 , 6 specimens, 44.2–69.9 mm SL from Dainichi River system, Jindaiurakabe , Hyogo; • FAKU 211491 , 1 specimen, 49.6 mm SL from Muko River system, Dojyo , Hyogo; • FAKU 211492 , 1 specimen, 40.0 mm SL from Yoshii River system, Nagi , Okayama; • FAKU 211493–211499 , 7 specimens, 39.0–60.0 mm SL from Maruyama River system, Santo , Hyogo; • FAKU 211500 , 1 specimen, 44.9 mm SL from Saburi River system, Yamada , Fukui; • FAKU 211501–211506 , 6 specimens, 35.6–57.4 mm SL from Onyu River system, Taneji , Kyoto.

L. tokaiensis , 22 specimens (32.8–60.9 mm SL). Holotype: • NSMT-P 132821 , 44.2 mm SL from Toyo River, Kadoya, Aichi; • FAKU 211507–211511 , 5 specimens, 32.8–51.3 mm SL from Yahagi River system, Myoken , Aichi; • FAKU 211512–211518 , 7 specimens, 33.8–54.4 mm SL from Toyo River system, Kadoya , Aichi; • FAKU 211519–211526 , 8 specimens, 40.7–60.0 mm SL from Miyakoda River system, Hosoe , Shizuoka; • FAKU 211527 , 1 specimen, 36.8 mm SL from Ota River system, Ota , Shizuoka.

Figures

Figure 1. Map of central Japan showing the distribution of three Lefua species. Orange, L. torrentis; red, L. tokaiensis; purple, L. nishimurai sp. nov. The distribution of L. torrentis and L. tokaiensis were in accordance with Yamada (2015) and Nakajima and Uchiyama (2017).

Figure 5. Comparison of body morphology and coloration of three Lefua species. A. Kii-Shikoku Population of L. torrentis (FAKU 211486); B. Sanyo Population of L. torrentis (FAKU 211492); C. Nihonkai Population of L. torrentis (FAKU 211504); D. L. tokaiensis (FAKU 211510); E. L. nishimurai sp. nov. (LBM 1210059189). Scale bar: 10 mm.

Figure 6. Comparison of dorsal view of the head of three Lefua species. A. Kii-Shikoku Population of L. torrentis (FAKU 211486); B. Sanyo Population of L. torrentis (FAKU 211492); C. Nihonkai Population of L. torrentis (FAKU 211504); D L. tokaiensis (FAKU 211510); E. L. nishimurai sp. nov. (LBM 1210059179). Scale bars: 5 mm.

Figure 7. Body coloration of the holotype of Lefua nishimurai sp. nov (LBM 1210059189). A. Lateral view; B. Dorsal view; C. Ventral view. Scale bar: 10 mm.

Figure 8. Detailed morphology of the holotype of Lefua nishimurai sp. nov (LBM 1210059189). A. Head; B. Lateral view of head; C. Mouth; D. Caudal fin base. An arrow in the lateral view of head (B) indicates narrow conspicuous black stripe between base of outer rostral barbel and eye. Arrows in the caudal fin base (D) indicate black spots on ventral and dorsal surfaces. Scale bars: 5 mm.

Figure 9. Body coloration of atypical specimen of Lefua nishimurai sp. nov. (LBM 1210059188), showing no distinct dark brown spots scattered over the body and obscure dark band in the skin of the caudal fin base. Scale bar: 10 mm.

Figure 10. Typical habitat of Lefua nishimurai sp. nov. in the Kuzuryu River drainage system in Fukui Prefecture, Japan.