Functions of the testicular gland in two blenniid fishes, Salaria (=Blennius) pavo and Lipophrys (= Blennius) dalmatinus (Blenniidae, Teleostei) as revealed by electron microscopy and enzyme histochemistry

The functions of the testicular gland in two different blenniid fishes, Salaria pavo and Lipophrys dulmutinus , are described by fine structural and enzyme histochemical methods. In the testes of the two fishes no mature spermatozoa are found. Sperrniogenesis occurs only until the spermatidal stage. Spermatids are released into the testicular gland. During the spawning period the testicular gland functions in differentiation of spermatids, nutrition of spermatids, and secretion of sialomucins. After spawning, the testicular gland has phagocytotic functions in resorbtion of remaining spermatids, which are transformed into lipids in the gland cells. During the interspawning period the testicular gland is a storage reservoir for lipids and phospholipids which are re-transformed into testicular gland secretion in the next reproductive season. Testicular gland cells themselves do not have steroidogenetic functions, but steroids are synthesized by interstitial cells homologous to Leydig cells in other fish. Possible explanations for the reduction of the testis in L. dalmatinus and implications of the testicular gland in taking over testicular functions are discussed.     

Scales and otoliths as identity cards of the Indian oil sardine Sardinella longiceps (Teleostei: Clupeiformes) populations: Ultrastructure and ornamentation characteristics using light and scanning electron microscopy

Scale and otolith morphology and morphometry of Indian oil sardine Sardinella longiceps (Clupeidae) were investigated and described using light and scanning electron microscopy from eight different body regions for scales and the right and left otoliths. Scales of the Indian oil sardine show general characteristics of the other studied clupeids sand that are easily distinguishable from other fish groups, by having striae in the posterior field. The studied cycloid scales of S. longiceps were classified into three types based on the overall shape including circular (e.g. true circular and cordate), pentagonal and quadrilateral in the different body regions. The circular shape was the most common shape (87.5%), while the quadrilateral and pentagonal forms constituted 6.25% each. The results also showed that the relative scale size (J-index) plays a desirable contribution in separating the examined populations. The results showed that the mean (or relative) scale size for all the eight regions in the Oman Sea population is larger than the Arabian Sea population. Also, another scale variable, the scale shape index (Si index), demonstrated variation (a mean of 0.86 to 1.1) in different regions of both populations from the Oman and Arabian Seas. Interestingly, here, we found that scale characters of S. longiceps not only differ from its other congeneric species, but also differ in the populations from both sides of the Oman Sea (Iran and Oman) and the Arabian Sea. It shows a positive signal for the presence of different taxonomic and management unit in the Oman and Arabian Seas. The idea should be approved by using integrated molecular and morphological traits. The otolith morphology of S. longiceps from the Oman and Arabian Seas was more conservative than the scales, which can be due to its function actin primarily as a balance organ and also enhancing hearing. The overall shape of S. longiceps otolith was lanceolate, with an elongated morphology and a well-developed rostrum, an ostial sulcus acusticus that opens to the anterior/ dorsal margin. These morphological characters are also found in the Iranian population of S. longiceps. However, otolith displayed variation in biometric parameters among two populations and left and right otoliths and the RRL parameter were important characters to discriminate the Oman and Arabian Sea populations. Thus, the structural/biometrical variability of the otoliths may be used for population distinctness, especially in water bodies with various environmental factors, and the otolith has turned out to be a useful tool to track the life history of teleostean fishes in environments with physicochemical gradients.     

First documentation of the otoliths of the species of Gouania (Teleostei: Gobiesocidae) in the Mediterranean Sea

Otolith morphology is a widely accepted tool for species identification in teleost fish, but whether this holds true for very small species remains to be explored. Here, the saccular otoliths of the cryptobenthic Mediterranean clingfish Gouania (Gobiesocidae) are described for the first time. The new data, although preliminary, indicate that otolith morphology and morphometry support the recognition of the recently differentiated five species of Gouania in the Mediterranean Sea. Furthermore, otoliths of phylogenetically closely related Gouania species resemble each other more than do those of the more distantly related species.     

Stock differentiation of the greater lizardfish Saurida tumbil (Teleostei: Synodontidae) collected along the western coast of the Arabian Gulf and Sea of Oman using meristic characters

Meristic variation among stocks of greater lizardfish Saurida tumbil through the western coasts of the Arabian Gulf and Sea of Oman was examined using meristic characters. Statistical analysis of meristic traits proposed that there is constrained migration of populations of greater lizardfish along the western coast of the Arabian Gulf and Sea of Oman. Overlapping of the two samples from the northern part of the Arabian Gulf (Iraq-Kuwait waters), three samples from the middle region of the Arabian Gulf (Bahrain-Qatar-Saudi Arabia) and two samples from the southern part of the Arabian Gulf/Sea of Oman (United Arab Emirates–Sultanate of Oman) suggested that there are three self-recruiting populations in the studied area. Inspection of the role of each meristic trait variable to Canonical discriminant analysis showed that changes among samples appeared to be linked with the pattern of distribution of water temperature and configuration of current in both the Arabian Gulf and Sea of Oman areas.     

A New Species of the Genus Tor from Yunnan, China (Teleostei: Cyprinidae)

A new species of the subfamily Barbinae, Tor yingjiangensis, is recognized from Yunnan province, China. It can be distinguished from other Tor species by the following combination of characters: last simple dorsal-fin ray osseous and non-serrated; no forward directed predorsal procumbent spine; head length considerably longer than body depth; no tubercles on the snout or sides of the face; 18–20 gill rakers on the outside of first gill arch; 24–26 lateral line scales; median lobe of lower lip short, its posterior margin truncate, not extending to the vertical across the inner corners of the mouth; and the condition of the lower lip consistent in individuals of different sizes. The new species has been misidentified previously as Tor putitora (Hamilton, F. 1822. An account of the fishes found in the River Ganges and its Branches. Edinburgh & London. 405 pp), which occurs in the Ganges and Indus River basins. The new species can easily be distinguished from T. putitora by having 3–3.5 (vs. 2.5) scales from lateral line to pelvic-fin origin, shorter caudal peduncle length (13.0% vs. 17.2% of standard length), lesser body depth (26.4% vs. 24.0% of standard length) and longer caudal peduncle depth (12.0% vs. 10.9% of standard length), no longitudinal stripe present along side of body, and eyes visible in ventral view of head.     

Molecular identification and phylogenetic relationships of Coleoidea (Mollusca: Cephalopoda) from the Persian Gulf and Oman Sea reveals a case of cryptic diversity

The Persian Gulf and Oman Sea constitute one of the most important marine ecosystems and have many economically important aquatic species, including several coleoid cephalopods. Some coleoids are difficult to identify using traditional morphological characteristics. In this study, two mitochondrial fragments, cytochrome oxidase I (COI) and the large ribosomal subunit (16S rRNA), were used for identification of coleoid species in four regions in the northern Persian Gulf and Oman Sea. The study led to the identification of potential cryptic species of Sepia, Amphioctopus and Uroteuthis. Furthermore, Euprymna hyllebergi was reported for the first time from the Persian Gulf. A high diversity of Coeloidea was found in the study area. Mean intraspecific and interspecific nucleotide distances for COI were 0%–2% and 2%–7%, respectively, while these values for 16S rRNA sequences were 0%–1% and 1%–4%. Given the uncertainty about species identity and the high levels of intraspecific genetic diversity reported for some species in GenBank, a comprehensive global study will be needed to resolve the taxonomic status of several coleoid species.     

A revision of the genus Labidochromis (Teleostei: Cichlidae) from Lake Malawi

The diagnosis of the genus Labidochromis is revised to include species with bicuspid outer teeth. Sixteen species, of which 13 are new, are described and illustrated and the validity of five others is discussed. The interrelationships between members of the genus and the relationship of the genus to other genera are discussed. No clearly defined sister group to the genus has been found either within or outside the Lake Malawi cichlid species flock. A key based on the coloration of known species is included.     

External sense receptors in microdrile oligochaetes (Annelida,Clitellata) as revealed by scanning electron microscopy: Typology and patterns of distribution in the main taxonomic groups

This work summarizes the observations on 30 species of microdriles belonging to the families Naididae (Rhyacodrilinae, Pristininae, Naidinae, Phallodrilinae, and Tubificinae), Phreodrilidae, Lumbriculidae, and Enchytraeidae using scanning electron microscopy. The lumbricid Eiseniella tetraedra, a megadrile species common in typical microdrile habitats, was used for comparison. Microdriles display external ciliate sense structures along the entire body; even at the clitellum and in budding and regeneration zones. According to the shape of the cilia, these sense structures can be divided into receptors of blunt cilia, receptors of sharp cilia, and composed receptors. Sense receptors can be morphologically unconspicuous or clearly defined on sensory buds or papillae. All microdriles studied have receptors of blunt cilia. Enchytraeids have characteristic receptors of short cilia. Pristina (Pristininae), Chaetogaster, Ophidonais, and Stylaria (Naidinae) have receptors of long blunt cilia. Composed receptors were found only in some microdriles and E. tetraedra. Receptors of sharp cilia have been found in most microdriles. Enchytraeids might be the only exception, but sharp cilia are probably present in the amphibiotic Cognettia sphagnetorum. Sensory cells with long sharp cilia might play a rheoreceptor role, and their presence in E. tetraedra and C. sphagnetorum would imply the reappearing of an ancient character that was probably lost with the transit from aquatic to terrestrial habitats. Some lumbriculids have ciliated fields. Anatomically, these structures appear as intermediate between the typical isolate sensory structures of microdriles and the sensillae of the hirudineans. The general pattern in microdriles is that uniciliate receptors and multiciliate receptors are separated, which supports the presumed aquatic origin of the clitellates. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

Morphological divergence in the Walton's Mudskipper,Periophthalmus waltoni Koumans, 1941, from the Persian Gulf and Gulf of Oman (Gobioidei: Gobiidae)

The body shape variation among 244 specimens of Periophthalmus waltoni Koumans, 1941, collected from seven stations in the Persian Gulf and Gulf of Oman, was analysed by utilising geometric morphometrics (GM) and truss-based morphometrics methods (TBM). Discriminant function analysis did not show significant differences between the shape of females and males. Canonical variate analysis and cluster analysis classified the specimens in two separate groups of stations: those in the Persian Gulf, and those in the Strait of Hormuz plus Gulf of Oman. Potential factors contributing to the observed variation include differences in physicochemical parameters between the Persian Gulf and the Gulf of Oman.     

Morphology and ontogenetic changes in otoliths of the mesopelagic fishes Ceratoscopelus maderensis (Myctophidae), Vinciguerria attenuata and V. poweriae (Phosichthyidae) from the Strait of Messina (Mediterranean Sea)

Fish otoliths morphology is an important aid in taxonomic, phylogenetic, palaeoichthyological and dietary studies. This study compares the morphology of the otoliths of the myctophid species, Ceratoscopelus maderensis, and two phosichthyid species, Vinciguerria attenuata and V. poweriae, collected from the Strait of Messina in the central Mediterranean Sea to identify the most appropriate taxonomical characters that separate these species. Ontogenetic changes in the otoliths of the studied fishes are evident. The sagitta of the juvenile C. maderensis is the most similar to the adult otoliths, while otoliths of the juvenile V. poweriae are the least similar to the adult otoliths. A discussion on possible geographical variations in otolith's morphology is provided by comparing our results with sagitta's images of C. maderensis, V. attenuata and V. poweriae in other studies.     

A taxonomic study on the genus Harpapion Voss, 1966 from China (Coleoptera,Apionidae)

Harpapion safranum sp. n. and Harpapion borisi sp. n. are described and figured. Harpapion vietnamense (Korotyaev, 1987) is recorded as new for China. The genitalia andterminalia of H. considerandum, H. coelebs andH. vietnamense are redescribed and redrawn. The diagnostic characters of Harpapion are defined. A key to the known species of the genus Harpapion from China is provided. Affinities with the genus Flavopodapion Korotyaev, 1987 are discussed.     

Gills of the medaka (Oryzias latipes): A scanning electron microscopy study

The general morphology and surface ultrastructure of the gills of adult and larvae medaka (Oryzias latipes) were studied in freshwater and seawater using scanning electron microscopy. The gills of all examined fish were structurally similar to those of other teleosts and consisted of four pairs of arches supporting (i) filaments bearing lamellae and (ii) rakers containing taste buds. Three cell types, specifically pavement cells, mitochondria‐rich cells (MRCs), and mucous cells, constituted the surface layer of the gill epithelium. Several distinctive characteristics of medaka gills were noted, including the presence of regularly distributed outgrowth on the lamellae, enlarged filament tips, the absence of microridges in most pavement cells in the filament and lamellae and the presence of MRCs in the arch at the filament base. A rapid mode of development was recorded in the gills of larval fish. At hatching, the larvae already had four arches with rudimentary filaments, rakers, and taste buds. The rudimentary lamellae appeared within 2 days after hatching. These results suggest the early involvement of larval gills in respiratory and osmoregulation activities. The responses of the macrostructures and microstructures of gills to seawater acclimation were similar in larvae and adult fish and included modification of the apical surface of MRCs, confirming the importance of these cells in osmoregulation. The potential roles of these peculiarities of the macrostructures and microstructures of medaka gills in the major functions of this organ, such as respiration and osmoregulation, are discussed.     

黑胸散白蚁下唇腺的解剖和扫描电镜观察

【目的】通过研究黑胸散白蚁Reticulitermes chinensis下唇腺解剖构造及其在不同品级个体间的分化,为进一步探索口交哺和品级分化机制提供参考。【方法】通过显微解剖观察,了解黑胸散白蚁下唇腺的形态构造及其在不同品级个体间的分化;通过扫描电镜观察,了解下唇腺的结构及神经支配;通过饮水实验,研究工蚁饮水及下唇腺囊的贮水功能。【结果】黑胸散白蚁下唇腺是左右对称结构,每侧构造由一个下唇腺腺泡群、一个下唇腺囊及相关的导管组成。每侧导管分别开口于舌基部下方。蚁后的下唇腺最发达,在下唇腺大小、下唇腺囊大小、腺泡大小及腺泡数量4方面均显著高于其他品级个体;兵蚁、工蚁、有翅成虫的下唇腺也较为发达,相互之间这4个参数的差异性不显著。扫描电镜观察发现,工蚁下唇腺腺泡由主导管和分支导管相连,腺泡外侧有神经分布。黑胸散白蚁工蚁有饮水习性,获得的水贮存在下唇腺囊内。【结论】黑胸散白蚁不同品级个体间,蚁后的下唇腺最发达,有翅成虫的下唇腺也比较发达,说明蚁后除行使生殖职能外,还承担交哺育幼等职能。黑胸散白蚁工蚁有饮水习性,下唇腺囊有贮水功能。     

Larval development of five species of blenny (Teleostei: Blenniidae) from the western central North Atlantic, with a synopsis of blennioid family characters

Light trap collections on oil and gas platforms in the northern Gulf of Mexico off Louisiana from 1995 to 1997 contained young of tessellated blenny Hypsoblennius invemar , freckled blenny Hypsoblennius ionthas , featherduster blenny Hypleurochilus multifilis , molly miller Scartella cristata and seaweed blenny Parablennius marmoreus , which are described. Interspecific differences were: number of dorsal, anal, pelvic and caudal fin elements; number of mandibular pores; presence or absence of canine teeth, hypural 5 and pectoral fin pigment; width of gill openings; length of preopercular spines (in larvae). Size at settlement differed among some taxa, but all five species settled within a narrow size window of c . 1·5 mm standard length ( L _S). Hypsoblennius invemar , H. ionthas , H. multifilis and S. cristata settled at mean sizes between 11·3 and 12·1 mm L _S, whereas P. marmoreus settled at a mean size of 19·3 mm L _S. Sexually dimorphic differences were consistently evident by 17–18 mm L _S in all species but P. marmoreus . The two smallest blennies with external characters normally associated with sexual maturity were a 20 mm male and 21 mm female H. multifilis . Primary caudal fin rays began to bifurcate between 17·0 and 18·3 mm L _S in H. invemar , H. ionthas , H. multifilis and S. cristata . Hypleurochilus multifilis displayed the external characteristics of being sexually mature at 20–21 mm L _S. Thus, bifurcation of primary caudal fin rays was an indicator of approaching sexual maturity in H. multifilis and this may also be true in the other species studied.     

A benign approach to the preparation of freshwater bryozoan statoblasts for scanning electron microscopy (SEM) imaging

Abstract

Several different species of freshwater Bryozoa, belonging to the genera Plumatella, Rumarcanella and Fredericella, were detected within the Northern Mallee Pipeline (NMP) system in Victoria, Australia, that required definitive identification. These organisms produce asexual buds called statoblasts, with valves composed of sclerotised chitin that bear minute micro-ornamentations of considerable taxonomical significance. Imaging and analysis of these distinctive micro-ornamentations using scanning electron microscopy (SEM) is often employed for species identification. Meticulous preparation of statoblast samples is therefore required that necessitates the removal of adhering debris, dehydration and drying—whilst mitigating specimen damage and distortion. This technical note describes an approach whereby each of these three steps have been individually designed to be as benign as possible, using mild detergent/sonication to remove debris, a gradual and gentle dehydration procedure using ethanol, and critical point drying. For the overall process, these methods are chosen to optimise control and to minimise the use of harsh and hazardous chemicals.     

Macro- and microscopic morphology of the flank scales of families Lutjanidae and Serranidae from the Persian Gulf Coral Reefs (Teleosts: Perciformes)

Macro- and microscopic characteristics of flank scales for 12 species were investigated from the Persian Gulf Coral Reefs. In Lutjanus argentimaculatus and L. russellii (family Lutjanidae), the scales of different flank regions were not different, while four characters showed variation in the scale of L. lutjanus i.e., scale shape (pentagonal, hexagonal and square), anterior margin (waved, scalloped and smooth), focus shape (circular and oblong) and focus position (postero-central and central), displayed variation. Scale type (ctenoid) and posterior margin (transforming ctenii) did not show variation and could be considered to be specific in this family. In Epinephelus chlorostigma (family Serranidae), the scales of flank regions did not display variation, while in E. areolatus, E. diacanthus and E. radiates, the scales showed considerable variation. The most variable characters were scale shape, posterior margin and focus shape. Therefore, in fish systematics studies on the base of scale, it is particularly important to compare scales from the same flank regions. Also, some criteria such as size-dependent alternation, ontogenetic changes and variation between flank regions, should be considered. This study supports the potential of scale morphology to help for the understanding of fish diversity in the coral reef ecosystem.