A taxonomic review of the platycephalid genus Kumococius Matsubara and Ochiai 1955, previously regarded as monotypic and represented solely by Kumococius rodericensis (Cuvier in Cuvier and Valenciennes 1829), resulted in the recognition of three species: Kumococius fenestra n. sp., K. rodericensis, and Kumococius timoriensis (Cuvier in Cuvier and Valenciennes 1829), the last-mentioned resurrected from the synonymy of K. rodericensis. Kumococius fenestra n. sp. is distinguished from its congeners by the absence of a long tentacular flap on the anterior nostril (present in the other two species) and a relatively broad semitranslucent (whitish) area on the pectoral fin (narrow in K. rodericensis). Kumococius timoriensis differs from its congeners in having a relatively short pectoral fin and relatively long uppermost preopercular spine, whereas K. rodericensis is characterized by a dark blotch anteriorly on the second dorsal fin. Mitochondrial COI sequences supported the recognition of the three species, with a minimum interspecific genetic distance of 10.3
The highest diversity of the family Uranoscopidae (commonly known as stargazers) is in the Indo-Pacific. Many guidebooks and studies from the region have found the number and identification of species to be difficult to determine, especially in the genus Uranoscopus. Herein we redescribe Uranoscopus bicinctus Temminck and Schlegel 1843 to address new information on the morphological variation across the species’ range that has contributed to taxonomic confusion. We use museum specimens and genetic data from across their distribution from Japan to Australia to explain differences in the body colouration (e.g., presence/absence of black spots) and the oral luring organ (e.g., complexity of cirri, tendrils). We then discuss taxonomic confusion in Uranoscopus bicinctus and compare to other uranoscopids to aid in future identification of this species.
Hybridization between closely related species provides insights into reproductive isolation and speciation. Here, we investigated hybridization between two minnow species, Rhynchocypris lagowskii and Rhynchocypris oxycephala, in the Seri River, Shiga Prefecture, central Japan, within their natural sympatric range. Mitochondrial DNA phylogeny confirmed that both species in this river represent native populations. Genome-wide SNP analyses using MIG-seq revealed clear genetic differentiation between the two species, with R. lagowskii predominating downstream and R. oxycephala upstream. Triangle plot analysis identified F1 hybrids (1.1
Lethenteron satoi is a species of brook lamprey recently described from a single river in the Ishikari River system, Hokkaido, Japan. To date, the species had been known only from the six specimens used in the original description, and its basic biological information remained extremely limited. Herein, we examined genetic and morphological variation in L. satoi based on 38 individuals collected from four rivers. Mitochondrial DNA analyses revealed that genetic diversity is highest in the lowland areas of the Ishikari River system and that populations are genetically differentiated from one another. Morphological analyses showed that a population from the upper reaches exhibits partially distinct characters and allow us to update the known ranges of metric traits for the species. We also provide new information on the distribution, ecology, and sexual dimorphisms of L. satoi. These findings provide a foundation for future conservation of this recently described species.
It is thought that sex change rarely occurs in high-density populations because small males are able to participate in spawning. We investigated sexual pattern of two wrasses, Halichoeres tenuispinis and Stethojulis interrupta terina, which inhabit Tateyama, Chiba, Japan at high densities, by histological observations on gonads. There were four types of sexual phases: female, IPPM (initial phase-colored primary male), TPPM (terminal phase-colored primary male), and TPSM (terminal phase-colored secondary male). In both species, the number of females and IPPMs was high, but the number of TPPMs and TPSMs was low, indicating that sex change seldom occurred and most IPPM did not change to TPPM. In conclusion, the results show that protogyny and gonochorism coexist and large IPPMs appear in the same population in both species.
