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PubMed1991

Pauciconfibula subsolana n. sp. (Monogenea: Microcotylidae) from Morone americana (Perciformes: Percichthyidae) collected in fresh water in New Brunswick, Canada.

Pauciconfibula subsolana n. sp. (Monogenea: Microcotylidae) is proposed for parasites found on the inner surface of the operculum of Morone americana collected in the freshwater reaches of the Saint John River, near Mactaquac, New Brunswick. Pauciconfibula subsolana is differentiated from other species in the genus by the 2 posterolateral clamp sclerites, each of which is composed of 2 distinct sections, and by the absence of appendages on the eggs. An amended generic diagnosis is provided for Pauciconfibula. Pseudoaspinatrium Mamaev, 1986, is considered a junior synonym of Pauciconfibula Dillon and Hargis, 1965, and the species previously assigned to Pseudoaspinatrium are transferred to Pauciconfibula as Pauciconfibula euzeti (Ktari, 1971) n. comb., Pauciconfibula gallieni (Euzet and Ktari, 1971) n. comb., and Pauciconfibula pogoniae (MacCallum, 1913) n. comb.

Animals↗
PubMed1989

Central projections of the lateral line nerves of Chelon labrosus (teleosts, order Perciformes).

The central projections of the anterior and posterior lateral line nerves were studied in the advanced teleost Chelon labrosus using silver staining techniques and anterograde axonal transport of horseradish peroxidase. The anterior lateral line nerve consists of two separated roots, dorsal and ventral. Both roots form descending and ascending tracts ending ipsilaterally in the octavolateral area and the granular eminence of the cerebellum. The posterior lateral line nerve enters the medulla oblongata in a single root originating ascending and descending tracts. Most of its fibres end in the octavolateral area whereas others reach the granular eminence dorsally to the anterior lateral line fibres. Contralateral projections of the lateral line nerves were not found. Lateral line fibres course below the cerebellar crest of the octavolateral area. They were never found ascending to the cerebellar crests as climbing-like fibres. The two neuron types found in the lateral are, Purkinje-like and oval shaped cells, have a different distribution pattern.

Afferent Pathways↗
PubMed1988

Three interesting nematodes from the fish Parupeneus indicus (Mullidae, Perciformes) of the Indian Ocean, including a new species, Ascarophis parupenei sp. n. (Habronematoidea).

In 1986, samples of the marine commercial fish Parupeneus indicus originating from the Indian Ocean near Somalia were examined for helminths. They proved to harbour three species of adult parasitic nematodes: Ascarophis parupenei sp. n., Philometra lateolabracis (Yamaguti, 1935), and Cucullanus himezi Yamaguti, 1941. A. parupenei sp. n. is characterized mainly by its non-filamented eggs with a fine flock-like coating, length ratio (1: 13-16) of the muscular and glandular parts of oesophagus, length of spicules (0.533-0.600 mm and 0.150-0.171 mm), structure of the head end and shape of the female tail. All these species are briefly described and illustrated and some problems concerning their taxonomy and geographical distribution are discussed.

Animals↗
PubMed1987

[Histological data on the pharyngeal jaws of Trachinotus teraia (Cuvier 1832), Carangidae (Osteichthyes, Perciformes) of tropical Africa].

The thick pharyngeal jaws of Trachinotus teraia are made up of small teeth embedded in an abundant acellular vascularized bone tissue. The diameter of the vascular canals is progressively reduced from the center of the jaw to the abrasive surface where they are wholly obliterated by bone tissue. Each tooth consists of a small cone of orthodentine without an apical hypermineralized cape. The teeth have a weak masticatory function compared to the surrounding bone tissue. The genesis of these teeth probably takes place in the inner part of the pharyngeal jaws; they then move progressively towards the abrasive surface. The inner localization of the first stages of dentinogenesis raises the question of an effective epidermal participation in the ontogenesis of the pharyngeal teeth in T. teraia.

Animals↗
PubMed1987

On the division of trypanosomes in Colisa fasciata (Perciformes) in vivo.

In vivo observation of the division in the trypomastigotes of the fish trypanosome, Trypanosoma trichogasteri, from Colisa fasciata is hereby reported for the first time. The division is initiated with the duplication of the kinetoplast followed by nuclear division and cytokinesis. Contrary to earlier reports, cytokinesis commences from the posterior end and the flagellum originates simultaneously or subsequent to cytoplasmic separation.

Animals↗
PubMed1994

A new species of Metabenedeniella (Monogenea: Capsalidae) from the dorsal fin of Diagramma pictum (Perciformes: Haemulidae) from the great barrier reef, Australia with a revision of the genus.

Metabenedeniella parva n. sp. is described from the marine teleost Diagramma pictum from Heron Island, Queensland, Australia. The type species of the genus, Metabenedeniella hoplognathi, is redescribed and the generic diagnosis emended. Metabenedeniella parva differs from M. hoplognathi in many respects: M. parva is smaller; in M. parva the accessory sclerites and anterior hamuli are of similar length, but the posterior hamuli are smaller, whereas in M. hoplognathi the accessory sclerites are longer than the anterior hamuli and the anterior and posterior hamuli are of similar length; in M. parva the anterior hamuli span the distance between accessory sclerites and posterior hamuli and the anterior hamuli overlap the posterior hamuli considerably, but in M. hoplognathi the anterior hamuli partially overlap the posterior hamuli and do not extend anteriorly to reach the accessory sclerites; a sclerite close to the common genital aperture in M. parva is absent from M. hoplognathi. The 2 species differ also in some of their soft body parts. Specimens reported previously from the gills of Plectorhynchus chaetodonoides off Okinawa, Japan as M. hoplognathi are considered to be M. parva. The discovery of M. parva from only the dorsal fin of D. pictum at Heron Island enhances the notion that some benedeniine monogeneans from the body surfaces of fish exhibit strong site specificity.

Animals↗
PubMed1997

Helminth ectoparasites of sillaginid fishes (Perciformes: Percoidei) have low species richness.

Just nineteen species of ectoparasitic helminths were found in a survey of over 1,500 individuals of 26 species of sillaginid fishes in the Indo-west Pacific. A twentieth worm is known only from the literature; a twenty-first, also known only from the literature, is considered a doubtful record. Fifteen of the twenty worms are branchial monogeneans, one is a monogenean of the pharyngeal plates, one is an ectoparasitic digenean living under the scales, and three are leeches of the mouth cavity and fins. The most common monogeneans were diplectanids (Diplectanum spp. and Monoplectanum spp.) and microcotylids (Polylabris spp.), each with five recently described or redescribed species. Of the remaining monogeneans, three were extremely rare, and two were uncommon. Pseudobivagina sp. and Polynemicola sp. (Microcotylidae) and Pseudempleurosoma sp. (Ancyrocephalidae) were represented by only a single worm each from three different hosts (Sillago robusta, S. sihama, and S. ingenuua, respectively). The gyrodactylid Gyrodactylus sp. is widespread and was recorded from four species of sillaginids (S. ciliata, S. japonica, S. schomburgkii and S. sihama). Encotyllabe chironemi Robinson (Capsalidae) is recorded for the first time from sillaginids, but only on S. aeolus. Two additional monogeneans are known from sillaginids only in the literature: Dactylogyrus sp. (Dactylogyridae) is known only from cultured S. sihama; the single specimen of Microcotyle sp. (Microcotylidae) recorded from Sillaginodes punctata is probably a contaminant, since the haptor was missing. The generalist trematode Transversotrema licinum Manter (Transversotrematidae) was found for the first time in samples of four species of sillaginids (Sillago analis, S. ingenuua, S. lutea and S. sihama). Three species of piscicolid leeches were encountered: Austrobdella translucens Badham was common on the fins of three large inshore sillaginids (S. ciliata, S. schomburgkii and S. analis); a single specimen of the generalist species Zeylanicobdella arugamensis De Silva was recovered from S. soringa; and specimens of Z. stellata (Moore) infected S. schomburgkii and S. analis. The diversity of host-specific worms in Sillaginidae is low compared with those of some other Indo-west Pacific fishes.

Animals↗
PubMed2001

Cytoarchitectonic study of the brain of a perciform species, the sea bass (Dicentrarchus labrax). I. The telencephalon.

A cytoarchitectonic analysis of the telencephalon of the sea bass Dicentrarchus labrax, based on cresyl violet-stained serial transverse sections, is presented. Rostrally, the brain of the sea bass is occupied by sessile olfactory bulbs coupled to telencephalic hemispheres. The olfactory bulbs comprise an olfactory nerve fiber layer, a glomerular layer, an external cellular layer, a secondary olfactory fiber layer, and an internal cellular layer. Large terminal nerve ganglion cells are evident in the caudomedial olfactory bulbs. We recognized 22 distinct telencephalic nuclei which were classified in two main areas, the ventral telencephalon and the dorsal telencephalon. The ventral telencephalon displays four periventricular cell masses: the dorsal, ventral, supracommissural, and postcommissural nuclei; and four migrated populations: the lateral, central, intermediate, and entopeduncular nuclei. In addition, a periventricular cell population resembling the lateral septal organ reported in birds is observed in the ventral telencephalon of the sea bass. The dorsal telencephalon contains 13 nuclei, which can be organized into five major zones: the medial part, dorsal part, lateral part and its ventral, dorsal, and posterior divisions, the central part, and posterior part. Based on histological criteria, two cell masses are recognized in the ventral division of the lateral part of the dorsal telencephalon. The nucleus taenia is found in the caudal area of the dorsal telencephalon, close to the ventral area. This study represents a useful tool for the precise localization of the neuroendocrine territories and for the tracing of the neuronal systems participating in the regulation of reproduction and metabolism in this species.

Animals↗
PubMed2002

Temperature sex determination in the European sea bass, Dicentrarchus labrax (L., 1758) (Teleostei, Perciformes, Moronidae): critical sensitive ontogenetic phase.

The temperature sex determination (TSD) mechanism in the European sea bass (Dicentrarchus labrax L.) was studied in respect to: a) the TSD sensitivity during the different developmental stages; and b) the intrapopulation correlation of sex determination with the growth rate up to the end of the TSD-sensitive period. At the stage of half-epiboly, eggs from the same batch were divided into four groups and subjected to different thermal treatments: a) 15 degrees C (G15 group) and b) 20 degrees C (G20 group) up to the middle of metamorphosis stage; c) 15 degrees C up to the end of yolk-sac larval stage and subsequently to 20 degrees C (G15-5 group); and d) 15 degrees C up to the end of the preflexion stage and then to 20 degrees C (G15-10 group). At the end of the treatments, size grading was applied and four additional populations were established from the upper (L) and lower (S) size portions of the G15 and G20 populations: G15L, G15S, G20L, and G20S. During the following growing phase, all populations were subjected to common rearing conditions. The sex ratios of each population were macroscopically determined at 190-210 mm mean total length. Female incidence was significantly affected (P < 0.05) by the different thermal treatments: 66.1% in the G15, 47.1% in the G15-10, 37.6% in the G15-5, and 18.1% in the G20 group. In addition, sex ratio was correlated with the growth rate of the fish up to the end of the TSD-sensitive period, with the larger fish presenting a significantly higher (P < 0.01) female incidence than the smaller fish in both thermal regimes tested: 73.1% in G15L vs. 57% in G15S, and 36.6% in G20L vs. 22.5% in G20S group. Results provide, for the first time, clear evidence that the sea bass is sensitive to TSD during all different ontogenetic stages up to metamorphosis, and that sex ratio is correlated with the growth rate of the fish well before the differentiation and maturation of the gonads.

Animals↗
PubMed1983

Adaptations for reflection of bioluminescent light in the gas bladder of Leiognathus equulus (Perciformes: Leiognathidae).

The gas bladder of leiognathid fishes functions not only in buoyancy but also in reflection of bioluminescent light from the circumesophageal light organ. Purine distribution, quality (guanine/hypoxanthine ratio), and concentration, as the basis for reflectivity, were assayed enzymatically for different portions of the gas bladder lining of the common leiognathid, Leiognathus equulus (Forskal). For highly reflective areas, the percentage of tissue wet mass and dry mass represented by purine was also determined. The results indicate that total purine content in the reflective areas of the leiognathid bladder was significantly higher than values determined for other similar, shallow water fishes; instead, purine content in these reflective areas was similar to that known for very deep-dwelling fishes, in which heavy purine deposition is correlated with high pressures and high oxygen concentrations in the bladder. In addition, the results show that differential purine distribution within the bladder correlates strikingly with the path of bioluminescent light. The dorsal bladder lining, the primary site of incident luminescence, had extremely high purine concentrations (averaging 2.80 mg/cm2), whereas the secondary reflective surfaces, the lateral (1.81 mg/cm2) and ventral (1.22 mg/cm2), portions, although high in purine content, had concentrations significantly lower than the dorsum. Areas through which light is transmitted, the light organ-bladder interface (0.09 mg/cm2) and the posterior region (0.19 mg/cm2), were greatly reduced in purine content. The enhancement of purine in the reflective portions of the bladder and the correlation of the differential distribution of purines with the path of light indicate that the L. equulus gas bladder is exquisitely adapted to function as a reflector of bioluminescent light.

Air Sacs↗
PubMed2006

Comparative morphology and cytology of the male sperm-transmission organs in viviparous species of clinid fishes (Clinidae: Teleostei, Perciformes).

This work comprises the first comparative study of the morphology and cytology of the sperm transmission organs in males of 14 species of viviparous clinid fishes (Clinidae, Blennioidei, Teleostei). The form and dimensions of these organs differ among the various species studied. The organs are composed of intra-abdominal ampullae, into which the sperm ducts and urinary bladder anchor, and an external protruding intromittent papilla used for insemination. The form of the ampullae differs among the various species, from pear-shaped to horseshoe-shaped. It increases in dimensions with increasing length of the male. In all the species this organ is covered by a connective-tissue tunic that encompasses both circular and longitudinal striated muscle bundles. The lumina of the ampullae harbor the epididymis, a strongly convoluted and plicated duct, which becomes filled with spermatozeugmata during reproduction. From here, the epididymis continues into the protruding intromittent papillae, where its folds gradually straighten at the apical part of the intromittent organ. The form and dimensions of this copulatory organ also differ in the various species. Papillae bearing taste buds are found on the apical parts of the intromittent organ, and it is probable that these, together with the difference in forms of the organ, help to prevent interspecific copulation.

Animals↗
PubMed1978

Cyclic changes in fine structure of the epithelium lining the ovary of the viviparous teleost, Cymatogaster aggregata (Perciformes: Embiotocidae).

The most striking morphological feature of the ovarian epithelium of Cymatogaster is the presence of intercellular dilations during much of the year. These dilations increase markedly in volume during the several months prior to ovulation and fertilization, and decrease in volume during the months of embryogenesis and gestation. The epithelium then returns to its initial, relatively undifferentiated state. The extracellular material within the dilations likely is synthesized in the cells adjacent to or within the dilations. Apparently most of this material is released into the ovarian lumen when the apicolateral margins of adjacent epithelial cells pull apart; possibly it serves as nutrient for developing embryos. In addition to supporting embryogenesis, the ovarian epithelium also apparently is involved in sperm storage. Sperm are maintained within pockets in the ovarian epithelium for the several months between insemination and fertilization. The cells lining the sperm pocket do not develop the intercellular dilations characteristic of most of the ovarian epithelium, and sperm remain associated only with the sperm pocket cells.

Animals↗
PubMed2001

Shape changes and growth trajectories in the early stages of three species of the genus Diplodus (Perciformes, Sparidae).

The larvae of three species of the genus Diplodus (Diplodus vulgaris, D. sargus, and D. puntazzo) colonize shallow waters along the Mediterranean coasts and, after a short period spent in the water column, they settle. For all three species this habitat transition is characterized by important shape changes mostly related to swimming capacity and feeding behavior. In this study, geometric morphometrics are used to characterize shape changes during the early juvenile life of specimens collected in a single locality in order to compare growth curves and allometric relationships. Size-related shape changes proved to be similar for all three species and are consistent with the ecological transition. A nonparametric smoothing technique (Loess) was used to fit the scatter of shape on size. The graphical representation (of most size-related shape variability) of this fitting technique shows how major shape changes are rapid for small sizes and slow down successively. The approach allows for the visualization of allometry and the fitting technique might help in defining the allometric growth pattern, thus contributing to the study of the autoecology of the species and in establishing terms for comparison with other ecologically or phylogenetically related species.

Animals↗
PubMed1994

Histological identification of osteocytes in the allegedly acellular bone of the sea breams Acanthopagrus australis, Pagrus auratus and Rhabdosargus sarba (Sparidae, Perciformes, Teleostei).

The bone of advanced teleost fishes such as those of the family Sparidae is said to lack osteocytes or to be acellular. Acellularity has been determined by apparent lack of osteocyte lacunae. This study questions the validity of this criterion. Scanning electron and light microscopy of paraffin and resin sections were used to show that the sides of sea bream mandibles consist of laminar parallel-fibred bone that we call tubular bone, because it contains tubules, and localised regions of Sharpey fibre bone. Osteocytes lie along the walls of tubules that also contain collagen fibril bundles (T-fibres), or in the lumens of tubules that do not contain T-fibres. We show that the osteocytes are derived from osteoblasts. The T-fibre system is different from other fibre systems that have been described. The tubules enclose wide T-fibres (lenticular in cross-section, maximum width about 8 microns) that taper at their ends and continue as thin T-fibres (round in cross-section, about 2 microns wide). The T-fibres originate in the periosteum. In mature tubular bone, spaces of increasing size develop around the osteocytes. Osteocytes are released from the bone matrix and become postosteocytes or bone-lining cells. Secondary bone lines the largest spaces. In Sharpey fibre bone, small osteocytes in small lacunae (about 2 microns wide) are found in columns parallel to the Sharpey fibres. Large osteocytes are found in large round spaces and are much larger than comparable osteocytes in lacunae in the bone of the salmon Salmo salar. We conclude that an absence of visible or conventional osteocyte lacunae does not mean that the cells themselves are absent. There are cells and two types of collagen fibre bundle in the tubules. The cells are osteocytes derived from osteoblasts, and these osteocytes apparently resorb bone with the result that large amounts of bone are destroyed. "Acellular" tubular and Sharpey fibre bone are types of cellular bone that differ from each other and from conventional cellular bone.

Animals↗