• Animal Systematics, Evolution and Diversity
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• v.16 no.2
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• pp.159-163
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• 2000

The gudgeon, Microphysogobio tungtingensis uchidai, originally described by Banarescu and Nalbant in 1973 is reduced to a junior synonym of M. yaluensis based on the 5 type specimens in the USNM. Confusion on the taxonomic position of Microphysogovbio t. uchidai seems to have resulted from the inadequate description of the papillae of the upper lip and the reference to the small specimens.

• Applied Microscopy
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• v.39 no.3
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• pp.245-252
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• 2009

The reproductive cells in testes of Microphysogobio yaluensis were investigated using light and electron microscopes. The testis of Microphysogobio yaluensis consisted of numerous testicular cysts contained synchronized cells. Sperms were full in testicular sacs of mature testes. Leydig cells were located among testicular cysts. The nucleus of primary spermatocytes was round and mitochondria were congregated in cytoplasm. The size of secondary spermatocyte was smaller than that of primary spermatocyte and the nucleus of a secondary spermatocyte was round or oval. In spermatids, the nucleus was round and electron-dense. In spermiogenesis, the nucleus was condensed and a flagellum started to be formed. The mitochondria were rearranged along the flagellum. The sperm had a round head, the acrosome was not found and a motile flagellum consisted of an axoneme with a typical 9+2 pattern of microtubule.

• Korean Journal of Ichthyology
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• v.11 no.1
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• pp.1-11
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• 1999

The five species of the genus Microphysogobio in Korea are reviewed with the keys to species and their illustrations: M. longidorsalis, M. jeoni sp. nov., M. koreeneis, M. yaluensis, and M. rapidus. Microphysogobio tungtingensis uchidai was treated as a junior synonym of M. yaluensis based on having the distinct papillae of upper lip and the color pattern on body sides by the examination of the type specimens. Microphysogobio jeoni is described as a new species from the specimens collected in the Naktong River, Han River and Keum River, Korea. it is well distinguished from the related species by the slender body, undeveloped papillae of upper lip and unspotted fins. Microphysogobio yaluensis was showed the clinal variations in the number of lateral line scales and vertebrae among the populations in the western drainages of Korea. It is remarked biogeographically that the five species of Microphysogobio are all endemics to Korea with the restricted ranges.

• Animal cells and systems
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• v.3 no.1
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• pp.17-21
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• 1999

A new species of gudgeon, Microphysogobio rapidus is described from 25 specimens collected from the Naktong River system, Korea. The new species is similar to Microphysogobio yaluensis but is distinguished from the latter and congeners by the combination of the following characteristics: number of papilla on the upper lip, 4.5 scales above the lateral line, short distance from the anus to the origin of the anal fin, wide scaleless area of the abdomen, nuptial colour consisting of a longitudinal green stripe on the lateral side of the body and bright blue colour of the suborbital region and operculum. A key to the species of Microphysogobio from Korea is also included.

• Korean Journal of Ichthyology
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• v.30 no.3
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• pp.161-166
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• 2018

The olfactory organ of Korean endemic fish Microphysogobio yaluensis are described anatomically and histologically, focused on relationship to its habitat and ecology. The paired olfactory organs are located at the dorsal snout, and externally consist of two semicircular nostrils and single nasal flap. They internally have rosette structure with 22 to 24 units of lamellae and the raphe inside the olfactory chamber. The lamella is made up of the sensory and the non-sensory epitheliums. The sensory epithelium has olfactory receptor neurons, supporting cells and basal cells whereas the nonsensory epithelium has stratified epithelial cells, ciliated non-sensory cells and mucous cells with acidic and neutral mucins. These structures might be considered that M. yaluensis has the olfactory organ which corresponds to the high sensitivity for its habitat and ecology, and is usable as a taxonomic key.

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.80.2-80
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• 1999

No Abstract, See Full Text

• Korean Journal of Ichthyology
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• v.29 no.4
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• pp.252-257
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• 2017

The oogenesis of the Microphysogobio yaluensis was investigated using light microscopy. Various developmental oocytes appeared in the ovary of the M. yaluensis. The oogenesis is largely divided into four stages: nuclear-chromatin stage, peri-nucleoli stage, vitellogenesis (yolk vesicle and yolk granule stages), and mature stage. The nuclear-chromatin is distributed in a large germinal vesicle as threads. The peri-nucleoli stage has many acidic nucleoli lining at the inner side of the nuclear membrane and an egg envelope just weakly starts. As the oogenesis gradually proceeds, they change to the vitellogenesis stage. The oocyte become to drastically increase and the marginal area of the ooplasm is covered with many vacuoles showing no negative reactions with hematoxylin and eosin staining, called the yolk vesicle stage. Many yolk vesicles-owned oocyte largely increase and as the development continues, its ooplasm is changed from the yolk vesicles to the yolk granules of eosinophilic. At the mature stage, lots of granules merged into a big yolk mass, acidophilic. Even at the mature stage, the egg envelope was still thin between the ooplasm and the follicular layer of the oocyte.

• Korean Journal of Ichthyology
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• v.20 no.1
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• pp.7-12
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• 2008

Study on spermatid and spermatozoon of a Korean endemic freshwater fish, Microphysogobio yaluensis, has been carried out by transmission electron microscope. Spermiogenesis involves conspicuous modifications intercelluar movement such as centrioles and mitochondria migration, nuclear depression and structural changes for instance chroatin condensation, excess of cytoplasm. The mature spermatozoa are similar to those of other cyprinids as follows: a spherical nucleus with a shallow nuclear fossa, a short midpiece containing several mitochondria and encircling the basal body of the flagellum. However there are some differences in the orientation of the centrioles,the number of the mitochondria and distribution of vesicles from other cyprinids. It could be concluded that the M. yaluensis spermiogenesis belongs to type 2, and its mature spermatozoon is charaterized by a unique feature which may provide a useful systematic character.

• Korean Journal of Ichthyology
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• v.4 no.1
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• pp.80-86
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• 1992

The ichthyofauna at the Dongchang Stream(a second tributary of the Naktong River) was surveyed from autumn to winter 1991. The fishes collected were 21 species, 18 genera belong to 7 families, and 9 species of them were found to be endemic species to Korea ; Squalidus gracilis majimae, Coreoleuciscus splendidus, Microphysogobio yaluensis, Cobitis longicorpus, Cobitis rotundicaudata, Niwaella multifasciata, Liobagrus mediadiposalis, Coreoperca herzi and Odontobutis platycephala. The dominat species were Zacco temmincki(37.3%)and Odontobutis platycephala(16.9%). and rare species were Pseudorasbora parva, Hemibarbus longirostris, Acheilognathus limbatus, Microphysogobio yaluensis, Cobitis rotundicaudata, Misgurnus mizolepis and Anguilla japonica. The indices of species diversity, eveness and dominant were 0.934, 0.707 and 0.293, respectively.

• Korean Journal of Environment and Ecology
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• v.36 no.4
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• pp.381-389
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• 2022

This study investigated the ecological characteristics of Microphysogobio yaluensis at Dugye Stream of Geum River basin from January to December 2021. The river bed structure of this species' habitat was rich in pebbles and gravel. The water depth ranged from 12 to 85 cm with an average of 23 cm, which was shallow. The stream velocity was rapid at 1.03±0.34(0.72-1.47) m/sec. The ratio of females to males was 1:0.86. The age according to the total length-frequency distribution as of summer (June, July) indicated that the group with less than 50 mm (30.4-49 mm) in total length was one year old, the group with 50-69 mm was two years old, and the group over 70-92 mm was three years old. Both male and female fish sexually matured at 50 mm long and two years old in June and July. The spawning season was from July to August, and the water temperature was between 25.8℃ and 28.2℃ during the period. The prosperous spawning season was July. The matured eggs were yellowish and spherical with a mean diameter of 0.52±0.16 (0.33-0.77) mm, and the average number of eggs found in the ovaries of mature female fish was 2,593 (1,343-4,672). As for the food of M. yaluensis, only attached algae, which grow by attaching to stones and gravel of the stream rapids, were identified. The feeding habit of M. yaluensis was reported to be herbivorous, ingesting Cyanophyta, Chlorophyta and Bacillariophya. Also, the species belonging to Bacillariophya and Chlorophyta were abundant in Dugye Stream.