A new species of torrent catfish, Liobagrusgeumgangensis (Teleostei, Siluriformes, Amblycipitidae), from Korea.

In a recent survey of populations of the Korean torrent catfish Liobagrus, a distinctive species was discovered from the Geum River and its tributaries flowing into the western coast of Korea, and here described as a new species, L.geumgangensissp. nov. It is distinguishable from other congeners by a combination of the following characters: I, 8 pectoral fin-rays; 52-56 caudal-fin rays; a relatively short occiput to dorsal-fin origin distance (6.9-9.8% SL); a short pelvic-fin insertion to anal-fin origin distance (11.9-17.3% SL); a long dorsal-fin base (10.6-13.5% SL); 8-9 gill rakers; 5-8 serrations on the pectoral fin; the body and fins are dark yellow, the margins of the dorsal, anal, and caudal fins are dark brown, but the outermost rim is faintly yellow. Analysis of the cytb gene also confirmed that L.geumgangensis is a monophyletic lineage distinct from other congeners.

Rationally Designed Bimetallic Co-Ni Sulfide Microspheres as High-Performance Battery-Type Electrode for Hybrid Supercapacitors.

Rational designing of electrode materials is of great interest for improving the performance of battery-type supercapacitors. The bimetallic NiCo2S4 (NCS) and CoNi2S4 (CNS) electrode materials have received much attention for supercapacitors due to their rich electrochemical characteristics. However, the comparative electrochemical performances of NCS and CNS electrodes were never studied for supercapacitor application. In this work, microsphere-like bimetallic NCS and CNS structures were synthesized via a facile one-step hydrothermal method by controlling the molar ratio of Ni and Co precursors. The physico-chemical results confirmed that microsphere-like structures with cubic spinel-type NCS and CNS materials were successfully fabricated by this method. When tested as the supercapacitor electrode materials, both NCS and CNS electrodes exhibited battery-type behavior in a three-electrode configuration with outstanding electrochemical performances such as specific capacity, rate performance and cycle stability. Impressively, the CNS electrode delivered a high specific capacity of 430.1 C g-1 at 1 A g-1, which is higher than 345.9 C g-1 of the NCS electrode. Furthermore, the NCS and CNS electrodes showed a decent cycling stability with 75.70 and 84.70% capacity retention after 10,000 cycles. Benefiting from the electrochemical advantage of CNS microspheres, we fabricated a hybrid supercapacitor (HSC) device based on CNS microspheres (positive electrode) and activated carbon (AC, negative electrode), which is named as CNS//AC. The assembled CNS//AC HSC device showed a large energy density of 41.98 Wh kg-1 at a power density of 800.04 W kg-1 and displayed a remarkable cycling stability with a capacity retention of 91.79% after 15,000 cycles. These excellent electrochemical performances demonstrate that both bimetallic NCS and CNS microspheres may provide potential electrode materials for high performance battery-type supercapacitors.

Fine structure of micropylar regions of Cobitis hankugensis, Iksookimia longicorpa and their unisexual natural hybrids.

Iksookimia longicorpa and Cobitis hankugensis are two species of fish distributed only on the Korean Peninsula. They have a unique reproductive ecology that naturally hybridizes into three widely known unisexual types, maintaining populations of almost all females. In this study, the fine structure of the micropyles of I. longicorpa, C. hankugensis and their hybrids was analyzed to find out how egg-sperm interaction, a common interspecies isolation mechanism, is possible between heterogeneous species. Analysis of 30 eggs from five females of each species revealed that all had one funnel-shaped micropylar region and a manhole-shaped micropyle canal. With the exception of C. hankugensis, which had no spiral grooves or ridges, the rest had counterclockwise spiral grooves and ridges on the micropylar region. All five species, however, showed identical groove patterns for the micropyle canal. The egg size was the largest in HL (one from the C. hankugensis locus with one from the I. longicorpa locus) and the smallest in C. hankugensis. In the hybrids, the HL type had the largest egg and HHL (two from the C. hankugensis locus with one from the I. longicorpa locus) type the smallest. For the diameter of the micropylar region and micropyle canal, the diploid I. longicorpa, C. hankugensis and HL were smaller than those of the triploid. In addition, as the ratio of the canal diameter to the eggs was lower in I. longicorpa than in C. hankugensis, it was confirmed that I. longicorpa has a relatively small micropyle canal compared with C. hankugensis.

Sperm motility analysis of Cobitis hankugensis, Iksookimia longicorpa (Teleostei, Cypriniformes, Cobitidae) and their unisexual natural hybrids.

Hybrid sterility is an inevitable phenomenon in the speciation process to avoid indiscriminate increases in species, but it is not always unconditional. We used computer assisted sperm analysis (CASA) to analyze sperm motility of Cobitis hankugensis, Iksookimia longicorpa, and their unisexual natural hybrids. In parental species, the sperm concentrations of C. hankugensis and I. longicorpa were 11.6 ± 4.8 × 109 and 16.5 ± 6.8 × 109 , respectively. For sperm motility, the total motility was higher in the parental species (C. hankugensis, 91.3%; I. longicorpa, 87.5%) than other hybrids. After 1 min, the motility duration was reduced to 14% in C. hankugensis and 3.3% in I. longicorpa. This result could indicate that the duration of sperm motility of C. hankugensis is longer than that of I. longicorpa up to 1 min after spermatozoa activation. All of the hybrids had a low concentration and it was distinct from their parent species. Total motility and other velocity parameters also showed significantly lower values except for the HHL (one from the C. hankugensis genome with two from the I. longicorpa genome) type motility measurement (13.6%). These results suggest that the hybrids derived from C. hankugensis and I. longicorpa, are not completely infertile, contrary to histological observations.

Morphology and histology of the olfactory organ of two African lungfishes, Protopterus amphibius and P. dolloi (Lepidosirenidae, Dipnoi).

The olfactory organs of two African lungfishes, Protopterus amphibius and P. dolloi, were investigated using a stereo microscope and a compound light microscope and were described anatomically, histologically, and histochemically. Like other lungfishes, these species present the following general features: i) elongated olfactory chamber (OC), ii) anterior nostril at the ventral tip of the upper lip, iii) posterior nostril on the palate of the oral cavity, iv) lamellae with multiple cell types such as olfactory receptor neurons, supporting cells, basal cells, lymphatic cells, and mucous cells (MC), and vi) vomero-like epithelial crypt (VEC) made of glandular epithelium (GE) and crypt sensory epithelium. Some of these features exhibit differences between species: MCs are abundant in both the lamellar and inner walls of the OC in P. amphibius but occur only in lamellae in P. dolloi. On the other hand, some between feature differences are consistent across species: the GE of both P. amphibius and P. dolloi is strongly positive for Alcian blue (pH 2.5)-periodic acid Schiff (deep violet coloration), and positive with hematoxylin and eosin and with Masson's trichrome (reddish-brown staining), unlike the MCs of the two species which stain dark red with both Alcian blue (pH 2.5)-periodic acid Schiff and Masson's trichrome but respond faintly to hematoxylin and eosin. The differing abundance of MCs in the two lungfishes might reflect different degrees in aerial exposure of the olfactory organ, while the neutral and acid mucopolysaccharide-containing VEC, as indicated by staining properties of the MCs, is evolutionary evidence that P. amphibius and P. dolloi are the closest living relatives to tetrapods, at least in the order Dipnoi.

Comparative Morphology and Morphometry of the Olfactory Organ in the Five Korean Torrent Catfishes, Genus Liobagrus, with a Taxonomic View.

The morphology and morphometry of the olfactory organ of Korean torrent catfishes, genus Liobagrus, consisting of only five endemic species, were investigated by stereo microscopy, scanning electron microscopy, and statistical analysis. They showed the same morphological structure, externally and internally, including a tubular anterior nostril, a slit posterior nostril, and a rosette structure with several linguiform lamellae. Interestingly, however, the lamellar number (LN) revealed specific characteristics useful to identify the five species anatomically: 16-19 in Liobagrus andersoni (with standard length, SL, 96.8 ± 5.5 mm, mean ± SD), 14-16 in Liobagrus obesus (86.9 ± 13.4 mm), 22-27 in Liobagrus mediadiposalis (99.8 ± 14.7 mm), 19-24 in Liobagrus somjinensis (90.1 ± 6.7 mm), and 14-18 in Liobagrus hyeongsanensis (74.0 ± 6.7 mm). Regarding SL, that of L. andersoni was longer than those of L. somjinensis and L. hyeongsanensis. As opposed to the SL, the LN to SL ratios of L. somjinensis (24.1 ± 2.1%) and L. hyeongsanensis (21.1 ± 1.4%) were greater than that of L. andersoni (18 ± 1.2%). These differences might be considered to reflect an interspecific morphological adaptation to micro-habitat according to olfactory importance and can be used as a taxonomic characteristic for this genus.

Microscopic research on the olfactory organ of the Far Eastern brook lamprey Lethenteron reissneri (Pisces, Petromyzontidae).

The olfactory anatomy and histology of Lethenteron reissneri were researched using a stereo microscope, a light microscope, and a scanning electron microscope. As in other lampreys, it shows same characters as follows: i) a single olfactory organ, ii) a single tubular nostril, iii) a single olfactory chamber with gourd-like form, iv) a nasal valve, v) a nasopharyngeal pouch, vi) a sensory epithelium (SE) of continuous distribution, vii) a supporting cells with numerous long cilia, viii) an accessory olfactory organ. However, the description of a pseudostratified columnar layer in the SE and Non SE is a first record, not reported in sea lamprey Petromyzon marinus. In particular, both 19 to 20 lamellae in number and olfactory receptor neuron's quarter ciliary length of the knob diameter differ from those of P. marinus. From these results, it might be considered that the olfactory organ of L. reissneri shows well adaptive structure of a primitive fish to slow flowing water with gravel, pebbles, and sand and a hiding habit into sand bottom at daytime. The lamellar number and neuron's ciliary length may be a meaningful taxonomic character for the class Petromyzonida.

Anatomy, ultrastructure and histology of the olfactory organ of the largemouth bass Micropterus salmoides, Centrarchidae.

The detailed anatomy, ultrastructure and histology of the olfactory organ of Micropterus salmoides were investigated by a stereo microscope, a light microscope, and a scanning electron microscope. Its external structure shows a tube-like anterior nostril to stick out and a posterior nostril flat to the skin surface. Meanwhile, its internal structure, the olfactory chamber, contains a fan-shaped rosette structure with 9 to 11 lamellae in adult fish over 35 cm in standard length (SL) and two accessory nasal sacs (ethmoidal and lacrimal sacs) were found. Interestingly, the rosette in young fish under 15 cm in SL was a longitudinal structure in parallel with each of 4-5 lamellae. Histologically, the sensory epithelium (SE) on the olfactory chamber consists of 5 types of cells: olfactory receptor neurons, supporting cells, basal cells, lymphatic cells and mucous cells. In contrast, the non-sensory epithelium (NSE) has stratified epithelial cells, lymphatic cells and mucous cells. The mucous cells of the SE are abundant and distributed densely in one row on the outermost superficial surface, but the one of the NSE are less than the SE. From these results, the olfactory characters of M. salmoides may be related with its ecological habit spending in the middle layer of stagnant water contaminated, more or less.

Comparative structural study of the zona radiata of the eggs of three Gobiobotia (Cyprinidae, Teleostei), endemic Korean freshwaters.

The genus Gobiobotia in Korea has only three species and all are endemic benthic freshwater fishes. Their oocytes were observed by light microscopy, scanning electron microscopy and transmission electron microscopy to investigate the characteristics of the zona radiata (ZR), a non-cellular envelope, which surrounds the egg. Various developmental cells appeared during the spawning season. During the yolk vesicles stage, which yolk vesicles are spherically developed in periphery of the cytoplasm and gradually increase in its number and size, the ZR becomes visible between its follicular layer and ooplasm. The morphological appearance of the ZR of each of the three species was unique: G. brevibarba had a ZR with villous structures, whereas that of G. macrocephala was honeycomb-like with porous structures. In contrast, G. naktongensis had a ZR with no structural modifications during oogenesis. Such differences in the same genus are not common. These results indicate that the structure of the ZR is a useful character for identification of the genus Gobiobotia and may reflect the types of microhabitats they inhabit.

A new species of torrent catfish, Liobagrus hyeongsanensis (Teleostei: Siluriformes: Amblycipitidae), from Korea.

A new species of torrent catfish, Liobargus hyeongsanensis, is described from rivers and tributaries of the southeastern coast of Korea. The new species can be differentiated from its congeners by the following characteristics: a small size with a maximum standard length (SL) of 90 mm; body and fins entirely brownish-yellow without distinct markings; a relatively short pectoral spine (3.7-6.5 % SL); a reduced body-width at pectoral-fin base (15.5-17.9 % SL); 50-54 caudal-fin rays; 6-8 gill rakers; 2-3 (mostly 3) serrations on pectoral fin; 60-110 eggs per gravid female.

Variability of egg envelopes in Korean spined loaches (Cobitidae).

Fifteen Korean cobitid species were investigated by the light and electron microscope to clarify the structure on the egg envelope of the oocyte. The egg envelope (zona radiata) consists of two layers: 1) zona radiata externa which is the site for attachment of various adhesive materials, and 2) zona radiata interna which consists of heterogeneous electron-dense multi layers. The external appearances ofthe egg envelope could be classified into seven types as follow: 1) granule (Cobitis sinensis, C. lutheri, C. tetralineata and Iksookimia yongdokensis), 2) villi (C. pacifica, I. koreensis, I. pumila, I. hugowolfeldi and Niwaella multifasciata), 3) papilla (I. longicorpa). 4) grapevine (I. choii), 5) hillock (Kichulchoia brevifasciata), 6) sawtooth-like form (Koreocobitis naktongensis) and 7) unadorned form (Misgurnus anguillicaudatus, M. mizolepis).