Habitat selection of the spined loach yamato complex (Cobitidae) was investigated at the River Saigo, Fukuoka Prefecture, Kyushu Island, Japan, during both the non-spawning (from January to March) and spawning (from April to June) seasons. The study site had one pool, two riffles, and one flood region during the spawning season and is 140 m long, located 4 km stream from the river mouth. The number of yamato complex individuals was checked, and 10 physical environmental parameters were measured to assess the microhabitat in 45 quadrates. The number of individuals was counted each month, and environmental measurements were conducted four times from January to June 2010. Akaike’s Information Criterion (AICc) and Generalized Linear Model (GLM) were utilized for analysis to verify the effect of the important environmental variables on the habitat of the yamato complex. A total of 184 individuals were captured during the non-spawning and spawning seasons. The populations of yamato complex correlated positively with the water depth during the non-spawning season and with short emergent hydrophytes during the spawning season. Individuals of the yamato complex were observed in the riffle part of the river with depth during the non-spawning season and in the temporary water area with vegetation during the spawning season.
Although the Onga River system is relatively small, it is home to three spined loach species, Cobitis takatsuensis, C . sp. ‘yamato’ complex, and C. striata (the Onga form of the middle race). The aim of the present study is to examine the relationship between the distribution pattern of the species and the physical parameters of the habitat. We mapped the distribution of these three species and measured six environmental factors at 86 points in this river system. Model selection was performed with a generalized linear model (GLM) using the AIC (Akaike’s Information Criterion) to find the best model for the distribution pattern of each species. The dependent variable was the presence/absence of each species, and the independent variables were six environmental factors. The environmental factors that had a positive effect were turbidity for C. takatsuensis, turbidity and river gradient for C. sp. ‘yamato’ complex, and turbidity, river gradient and width of dry riverbed for C. striata. In addition, the coexisting fish species also differ among the three loaches. These results revealed that the three spined loach species select particularly different habitats and can therefore coexist in this small river system.
A revisionary study revealed two species of monogeneans, Dactylogyrus crucis Rogers, 1967 and Dactylogyrus lythruri sp. n., parasitising Lythrurus Jordan (formerly a subgenus of Notropis Rafinesque, 1818). New records and updated taxonomy of seven of 12 known minnows of the genus of Lythrurus are provided for D. crucis. A record of Dactylogyrus attenuatus Mizelle et Klucka, 1953 (syn. Dactylogyrus umbratilus [Kimpel, 1939], nomen nudum) on Lythrurus umbratilis (Girard) is referrable to D. crucis. Dactylogyrus lythruri is described from eight species of Lythrurus. It most closely resembles Dactylogyrus beckeri Cloutman, 1987, but is distinguished by having a smaller base of the male copulatory organ (MCO) and lacking a ventral enlargement of the distal end of the basal process. Previous reports of Dactylogyrus banghami Mizelle et Donahue, 1944 and Dactylogyrus cf. beckeri Cloutman, 1987 from Lythrurus atrapiculus (Snelson) and Lythrurus bellus (Hay) from Alabama, and Dactylogyrus confusus Mueller, 1938 from L. umbratilis in Illinois are herein relegated to D. lythruri. Four species of Lythrurus appeared not to be infected with Dactylogyrus., Donald G. Cloutman, Andrew B. Adrian, Chris T. McAllister, Bruce W. Stallsmith, Thomas J. Fayton and Henry W. Robison., and Obsahuje bibliografii