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| Lefua nishimurai Katayama, in Katayama et Sawada, 2024. |
Abstract
Eight-barbel loaches belonging to the genus Lefua have diverged into seven species in freshwaters of East Asia. Recent studies have discovered a new population in the Kuzuryu River drainage system of Fukui Prefecture, central Japan. Based on the results of the genetic analyses and morphological comparisons, we describe this population as a new species, Lefua nishimurai sp. nov. Body width, interorbital width, orbit diameter, preanal length, snout length, and the newly examined head width greatly contributed to the discrimination between L. torrentis, L. tokaiensis and L. nishimurai sp. nov. The new species can be distinguished from other congeners by combining the following characteristics: 1) eyes positioned dorsally on the head; 2) a narrow conspicuous longitudinal mark between the base of the outer rostral barbel and the eye; 3) small dark spots on the body, dorsal, and caudal fins; 4) a small dorsal fin and eye diameter; and 5) black spots above and below the base of the caudal fin. Based on the phylogenetic relationships of the genus, L. nishimurai sp. nov. is estimated to have diverged early from its common ancestor in central Japan. Understanding the natural history of this new species and implementing conservation measures are crucial because of its narrow, fragmented distribution and presence in vulnerable habitats.
Key Words: endangered species, freshwater fish, inland water, nemacheilid loach, nuclear phylogeny, species richness
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| 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. |
Lefua nishimurai Katayama, sp. nov.
New Standard Japanese name: Reihoku-nagare-hotoke-dojyô
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).
Etymology: The specific name is dedicated to Toshiaki Nishimura, who first morphologically distinguished this new species.
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| 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. Lefua nishimurai sp. nov. (LBM 1210059189). Scale bar: 10 mm. |
Yuta Katayama and Naoto Sawada. 2024. Integrative Taxonomy revealed A New Species of Lefua (Teleostei, Nemacheilidae) from Fukui Prefecture, Japan. Evolutionary Systematics. 8(2): 247-260. DOI: doi.org/10.3897/evolsyst.8.131002
