The somatic musculature of Bryceella stylata (Milne, 1886) (Rotifera: Proalidae) as revealed by confocal laser scanning microscopy with additional new data on its trophi and overall morphology

The monogonont rotifer Bryceella stylata was investigated with light, electron and confocal laser scanning (CLSM) microscopy to provide detailed insights into its anatomy and new information for future phylogenetic analyses of the group. Results from CLSM and phalloidin staining revealed a total of six paired longitudinal muscles (musculi longitudinales I-VI) and eight circular muscles (musculi circulares I-VIII) as well a complex network of mostly fine visceral muscles. In comparison with other rotifer species that have been investigated so far, B. stylata shares the presence of the circular and longitudinal muscles: musculus longitudinalis ventralis, musculus longitudinalis lateralis inferior, musculus longitudinalis dorsalis, musculus longitudinalis capitis and musculus circumpedalis. However, the species lacks lateral and dorsolateral longitudinal muscles and some circular muscles (e.g., corona sphincter, musculus pars coronalis). With light and electron microscopy, we were able to document the precise number of pseudosegments and the arrangement of the chambers comprising the trophi elements. Furthermore, our observations revealed several new morphological characteristics, including a shield-like epidermal projection covering the dorsal antenna, an epidermal projection restricting the corona caudally and an unpaired hypopharynx with distinct shovel-like structures.     

The musculature of Squatinella rostrum (Milne, 1886) (Rotifera: Lepadellidae) as revealed by confocal laser scanning microscopy with additional new data on its trophi and overall morphology

Wilts, E.F., Wulfken, D., Ahlrichs, W.H. and Martínez Arbizu, P. 2012. The musculature of Squatinella rostrum (Milne, 1886) (Rotifera: Lepadellidae) as revealed by confocal laser scanning microscopy with additional new data on its trophi and overall morphology.—Acta Zoologica (Stockholm) 93 : 14–27. The monogonont rotifer Squatinella rostrum was investigated with light, scanning electron and confocal laser scanning microscopy to reveal new morphological data on its inner and outer anatomy. In total, the visualized somatic musculature displays five paired longitudinal muscles (musculi longitudinales I–V) and nine circular muscles (musculi circulares I–IX). Compared to other species, S. rostrum is characterized by the absence of several longitudinal and circular muscles (e.g. musculus longitudinalis capitis, corona sphincter and pars coronalis). A reconstruction of the mastax musculature revealed a total number of seven paired and two unpaired mastax muscles. Possibly homologous somatic and mastax muscles in other, thus far investigated rotifers are discussed. Moreover, we provide a phylogenetic evaluation of the revealed morphological characters and suggest possible autapomorphic characters supporting Squatinella and Lepadellidae. Finally, we refer to some striking similarities in the morphology, ecology and way of movement of Squatinella and Bryceella that may indicate a closer relationship of both taxa.     

Organisation of body musculature in Encentrum mucronatum Wulfert, 1936, Dicranophorus forcipatus (O. F. Müller, 1786) and in the ground pattern of Ploima (Rotifera: Monogononta)

Fluorescence-labelled phalloidin in combination with confocal laser scanning microscopy (cLSM) has been used to reconstruct the body musculature in Encentrum mucronatum and Dicranophorus forcipatus in order to gain insight into the architecture of body musculature in representatives of the hitherto uninvestigated Dicranophoridae.

In both species, a system of outer circular and inner longitudinal muscles has been found. In E. mucronatum, seven circular muscles (musculi circulares I–VII) and six paired longitudinal muscles (musculi longitudinales I–VI) have been identified. In D. forcipatus, eight circular muscles (musculi circulares I–VIII) and nine paired longitudinal muscles (musculi longitudinales I–IX) are present. In both species, some of the longitudinal muscles span the whole specimen, while others are shorter and connect head and trunk or foot and trunk. Differences in shape and extension of the circular muscles in both species are related to differences in structure of the trunk integument.

Surveying the literature on rotifer musculature, muscles identified in this study are homologised across Rotifera and given individual names. Based on the study of E. mucronatum and D. forcipatus and previous studies on other rotifers, a system of musculature in the ground pattern of Ploima comprising at least three circular muscles (pars coronalis, corona sphincter, musculus circumpedalis) and three pairs of longitudinal muscles (musculi longitudinales ventrales, musculi longitudinales dorsales and musculi longitudinales capitum) is suggested.     

<Emphasis Type="Italic">Rhinoglena kutikovae</Emphasis> n.sp. (Rotifera: Monogononta: Epiphanidae) from the Bunger Hills,East Antarctica: a probable relict species that survived Quaternary glaciations on the continent

A new species of rotifer, Rhinoglena kutikovae n.sp. (Monogononta: Epiphanidae), is described from a freshwater lake in the Bunger Hills, East Antarctica. The new taxon is characterized by the following combination of characters: body conical to vase-shaped; a single toe; distal foot pseudosegment bulged; tail prominent, semi-circular; two small spherical pedal glands with common duct, forming a complex with caudal ganglion; trophi with seven major teeth with offset head and two smaller teeth without offset head. The new species is compared with R. fertoeensis, R. frontalis and R. tokioensis, of which scanning electron microscopic information is presented of the trophi. R. kutikovae n.sp. is probably a relict species that survived Quaternary glaciations in glacial lacustrine refugia on the Antarctic continent.     

Morphology of the proboscis of Hubrechtella Juliae (nemertea,pilidiophora): Implications for pilidiophoran monophyly

The proboscis of Hubrechtella juliae was examined using transmission electron microscopy, scanning electron microscopy, and confocal laser scanning microscopy to reveal more features of basal pilidiophoran nemerteans for morphological and phylogenetic analysis. The proboscis glandular epithelium consists of sensory cells and four types of gland cells (granular, bacillary, mucoid, and pseudocnidae‐containing cells) that are not associated with any glandular systems; rod‐shaped pseudocnidae are 15–25 μm in length; the central cilium of the sensory cells is enclosed by two rings of microvilli. The nervous plexus lies in the basal part of glandular epithelium and includes 26–33 (11–12 in juvenile) irregularly anastomosing nerve trunks. The proboscis musculature includes four layers: endothelial circular, inner diagonal, longitudinal, and outer diagonal; inner and outer diagonal muscles consist of noncrossing fibers; in juvenile specimen, the proboscis longitudinal musculature is divided into 7–8 bands. The endothelium consists of apically situated support cells with rudimentary cilia and subapical myocytes. Unique features of Hubrechtella's proboscis include: acentric filaments of the pseudocnidae; absence of tonofilament‐containing support cells; two rings of microvilli around the central cilium of sensory cells; the occurrence of subendothelial diagonal muscles and the lack of an outer diagonal musculature (both states were known only in Baseodiscus species). The significance of these characters for nemertean taxonomy and phylogeny is discussed. The proboscis musculature in H. juliae and most heteronemerteans is bilaterally arranged, which can be considered a possible synapomorphy of Hubrechtellidae + Heteronemertea (= Pilidiophora). J. Morphol. 274:1397–1414, 2013. © 2013 Wiley Periodicals, Inc.     

Combining confocal laser scanning and transmission electron microscopy for revealing the mastax musculature in Bryceella stylata (Milne, 1886) (Rotifera: Monogononta)

The rotiferan jaw apparatus (mastax) is characterized by enormous plasticity and according to morphology and feeding strategy, different mastax types can be distinguished. The cuticular hard parts (trophi) of the mastax are often highly specialized and have both a major taxonomic and phylogenetic relevance. Owing to numerous light and scanning electron microscopic studies, the morphology of the trophi is well known but only few attempts have been made to analyze the morphology and functionality of the mastax as a whole. Particularly, the complex muscular system connecting the individual trophi elements and moving them against each other was disregarded in the past. Therefore, the subject of the present study is a detailed analysis of the mastax musculature of the proalid rotifer Bryceella stylata using a combination of transmission electron and confocal laser scanning microscopic techniques, previously applied for revealing the somatic musculature in rotifers exclusively. Based on ultrathin serial sections and phalloidin-dyed specimens, a total number of six paired and two unpaired individual mastax muscles have been identified for the modified malleate trophi system of B. stylata. Possibly homologous muscles in other, so far investigated rotifer species are discussed as well as functional considerations of the individual mastax muscles and their interaction when moving the trophi elements are suggested.     

Musculature of the penial complex: A new criterion in unravelling the phylogeny of Hygrophila (Gastropoda: Pulmonata)

The taxonomy of freshwater pulmonates (Hygrophila) has been in a fluid state warranting the search for new morphological criteria that may show congruence with molecular phylogenetic data. We examined the muscle arrangement in the penial complex (penis and penis sheath) of most major groups of freshwater pulmonates to explore to which extent the copulatory musculature can serve as a source of phylogenetic information for Hygrophila. The penises of Acroloxus lacustris (Acroloxidae), Radix auricularia (Lymnaeidae), and Physella acuta (Physidae) posses inner and outer layers of circular muscles and an intermediate layer of longitudinal muscles. The inner and outer muscle layers in the penis of Biomphalaria glabrata consist of circular muscles, but this species has two intermediate longitudinal layers separated by a lacunar space, which is crossed by radial and transverse fibers. The muscular wall of the penis of Planorbella duryi is composed of transverse and longitudinal fibers, with circular muscles as the outer layer. In Planorbidae, the penial musculature consists of inner and outer layers of longitudinal muscles and an intermediate layer of radial muscles. The penis sheath shows more variation in muscle patterns: its muscular wall has two layers in A. lacustris, P. acuta, and P. duryi, three layers in R. auricularia and Planorbinae and four layers in B. glabrata. To trace the evolution of the penial musculature, we mapped the muscle characters on a molecular phylogeny constructed from the concatenated 18S and mtCOI data set. The most convincing synapomorphies were found for Planorbinae (inner and outer penis layers of longitudinal muscles, three-layered wall of the penis sheath). A larger clade coinciding with Planorbidae is defined by the presence of radial muscles and two longitudinal layers in the penis. The comparative analysis of the penial musculature appears to be a promising tool in unraveling the phylogeny of Hygrophila.     

External Morphology and Muscle Arrangement of Brachionus urceolaris, Floscularia ringens, Hexarthra mira and Notommata glyphura (Rotifera, Monogononta)

We studied four monogonont rotifers (Brachionus urceolaris, Floscularia ringens, Hexarthra mira, Notommata glyphura) using two different techniques of microscopy: (1) the presence of filamentous actin was examined using phalloidin-fluorescent labelled specimens and a confocal laser scanning microscope (CLSM); (2) external morphology was investigated using a scanning electron microscope (SEM). B. urceolaris, F. ringens, and N. glyphura showed similar patterns of muscle distribution: a set of longitudinal muscles acting as head and foot retractors, and a set of circular muscles. However, the size and distribution of circular muscles differed among these species. H. mira differed from the other species in that it lacked circular muscles but possessed strong muscles that extended into each arm. The study showed that using both CLSM and SEM provides better resolution of the anatomy and external morphology of rotifers than using one of these techniques alone. This can facilitate better understanding of the complicated anatomy of these animals.     

Combining confocal laser scanning and transmission electron microscopy for revealing the mastax musculature in Bryceella stylata (Milne, 1886) (Rotifera: Monogononta)

The rotiferan jaw apparatus (mastax) is characterized by enormous plasticity and according to morphology and feeding strategy, different mastax types can be distinguished. The cuticular hard parts (trophi) of the mastax are often highly specialized and have both a major taxonomic and phylogenetic relevance. Owing to numerous light and scanning electron microscopic studies, the morphology of the trophi is well known but only few attempts have been made to analyze the morphology and functionality of the mastax as a whole. Particularly, the complex muscular system connecting the individual trophi elements and moving them against each other was disregarded in the past. Therefore, the subject of the present study is a detailed analysis of the mastax musculature of the proalid rotifer Bryceella stylata using a combination of transmission electron and confocal laser scanning microscopic techniques, previously applied for revealing the somatic musculature in rotifers exclusively. Based on ultrathin serial sections and phalloidin-dyed specimens, a total number of six paired and two unpaired individual mastax muscles have been identified for the modified malleate trophi system of B. stylata. Possibly homologous muscles in other, so far investigated rotifer species are discussed as well as functional considerations of the individual mastax muscles and their interaction when moving the trophi elements are suggested.     

Presence of anisotropic (birefringent) crystalline structures in embryonic and juvenile monogonont rotifers

A systematic survey for the presence of birefringent (anisotropic) structures in rotifers was undertaken. Several common features of rotifers exhibit anisotropism (e.g. trophi & muscles). However, unusual anisotropic crystalline structures (ACS) were found in late stage embryos (i.e. possessing eyespots and trophi, and showing movement). ACS were found in 18 of 26 species of monogonont rotifers (comprising 11 genera of 5 families). In Sinantherina socialis, ACS were present in the lower gut as compact, spherical masses of minute crystals that slowly broke apart and disappeared within 20 hours of hatching. Although several authors have described the existence of refractive bodies in rotifers, to my knowledge this is the first report of their birefringent properties.     

The musculature of three species of gastrotrichs surveyed with confocal laser scanning microscopy (CLSM)

The muscular system of gastrotrichs consists of circular, longitudinal and helicoidal bands that when analysed with confocal laser scanning microscopy, provide new insights into their functional organization and phylogenetic importance. We therefore undertook a comparative study of the muscle organization in three species of Gastrotricha from the orders Macrodasyida (Paradasys sp., Lepidodasyidae; Turbanella sp., Turbanellidae) and Chaetonotida (Polymerurus nodicaudus, Chaetonotidae). The general muscle organization of the marine interstitial macrodasyidans, Paradasys and Turbanella, not only confirms earlier observation on other species but also adds new details concerning the organization and number of helicoidal, longitudinal and other muscle bands (e.g. semicircular band). The freshwater, epibenthic–epiphytic chaetonotid, Polymerurus nodicaudus, has a similar muscular organization to other species of Chaetonotidae, especially species of Chaetonotus, Halichaetonotus and Lepidodermella. Perhaps unique to Polymerurus is the combined presence of an unbranched Rückenhautmuskel (also in Halichaetonotus and Lepidodermella) and a specialized dorsoventral caudal muscle, which flank the splanchnic component of the longitudinal muscles (only in Chaetonotus and Lepidodermella). This combination, together with the presence of splanchnic dorsoventral muscles, known only in Xenotrichulidae, implies a unique phylogenetic position for Polymerurus, and indicates a potential basal position of this taxon among the Chaetonotidae studied so far (i.e. Aspidiophorus, Chaetonotus, Halichaetonotus and Lepidodermella).     

Ultrastructure structure of antennal sensilla of carabid beetle Carabus elysii Thomson, 1856 (Coleoptera: Carabidae)

The sensilla type, number and distribution in male and female adults of Carabus elysii Thomson, 1856 (Coleoptera: Carabidae) were studied using scanning electron microscopy. The results showed that there are seven categories and 12 types of sensilla in C. elysii adults: three types of S.Ch, three types of S.T, two types of S.B and one each of B.B, S.Co, S.Ca and S.Cam. There is no difference between male and female in the types of sensilla. Apart from the significant difference in the number and distribution of S.B.2, S.Co and S.Ca between male dorsal and ventral surfaces, there are no significant differences between male and female antennae. In general, the number of sensilla in females is larger than that in males. The results provide a basic reference for future ultrastructure, electrophysiological, and comparative behavioral studies of Carabus species.     

Reconstruction of the musculature of <Emphasis Type="Italic">Magelona</Emphasis> cf. <Emphasis Type="Italic">mirabilis</Emphasis> (Magelonidae) and <Emphasis Type="Italic">Prionospio cirrifera</Emphasis> (Spionidae) (Polychaeta,Annelida) by phalloidin labeling and cLSM

Recent investigations have suggested that a lack of circular muscle fibers may be a common situation rather than a rare exception in polychaetes. As part of a comparative survey of polychaete muscle systems, the F-actin musculature subset of Magelona cf. mirabilis and Prionospio cirrifera were labeled with phalloidin and three-dimensionally analyzed and reconstructed by means of cLSM. Obvious similarities are sublongitudinal lateral, circumbuccal, palp retractor, dominating dorsal longitudinal, perpendicular lateral and ventral transverse muscles. Differences between M. cf. mirabilis and P. cirrifera are: (1) two types of prostomial muscles (transversal and longitudinal) in M. cf. mirabilis versus one type (diagonal) in P. cirrifera; (2) one type of palp muscles (longitudinal) in M. cf. mirabilis versus three types (longitudinal, diagonal, circular) in P. cirrifera; (3) five ventral longitudinal muscles (ventromedian, paramedian, ventral) in M. cf. mirabilis versus four (two paramedian, two ventral) in P. cirrifera. Ventral and lateral transverse fibers are present in the thorax, but absent in the abdomen of M. cf. mirabilis. The triangular lumen of the pharynx in M. cf. mirabilis is surrounded by radial muscle fibers; three sets of pharynx diductors attach to its dorsal side. The unique features of P. cirrifera are one pair of brain muscles and segmentally arranged dorsal transverse muscles, the latter located outside the longitudinal muscles. The transverse lateral muscles are restricted to the sides and lie beneath the longitudinal muscles, a pattern described here for the first time. A true, outer layer of circular fibers is absent in both species of Spionida that were investigated.     

The organization of the muscle system of the causative agent of dicrocoeliosis,Dicrocoelium dendriticum

The musculature of parasitic flatworms plays a central role in locomotory movement, attachment to the host, and in the function of the digestive, reproductive, and excretory systems. We examine for the first time the muscle system of the flatworm Dicrocoelium dendriticum, a causative agent of the parasitic disease dicrocoeliosis, by use of fluorescently labeled phalloidin and confocal laser scanning microscopy. Somatic musculature of D. dendriticum consists of the circular, longitudinal, and diagonal muscles. The distribution of the muscle fibers in the body wall differed among the anterior, middle, and posterior body regions of the worm. The musculature of the attachment organs, the oral and ventral suckers, includes several types of muscles: the external equatorial and meridional muscles, internal circular and semicircular muscles, and radial muscles. Inside of the ventral sucker the diagonally located muscles were revealed and the supplementary u-shaped muscles were found adjoined to the base of the sucker from outside. The musculature of the internal organs composed of the excretory, reproductive, and digestive systems were characterized. Our results increase our knowledge of the morphology of trematodes and the arrangement of their muscle system.     

Musculature in polychaetes: comparison of Myrianida prolifera (Syllidae) and Sphaerodoropsis sp. (Sphaerodoridae)

Abstract. The relationship of the polychaete taxa Syllidae and Sphaerodoridae within Phyllodocida is still unresolved: phylogenetic analyses either show them as sister groups or more widely separated. The present article aims to provide information about the structure of the muscular system that could be essential for understanding their relationship. A crucial point is whether the body wall contains circular muscles, which has recently been shown to be absent in more taxa than previously known. The F-actin filaments in members of Myrianida prolifera (Syllidae) and Sphaerodoropsis sp. (Sphaerodoridae) were labeled with phalloidin and their three-dimensional relationships reconstructed by means of confocal laser scanning microscopy. Among the noteworthy differences that emerged between the species are (1) members of M. prolifera possess four, those of Sphaerodoropsis sp. eight, longitudinal muscle strands; (2) the body wall in M. prolifera contains transverse fibers in a typical, supralongitudinal position, while in Sphaerodoropsis sp., corresponding fibers lie beneath the longitudinal strands; (3) pro- and peristomium in M. prolifera have no distinct F-actin fibers, while five longitudinal pairs and three single transverse muscular fibers shape the anterior end in Sphaerodoropsis sp.; (4) the proventricle of M. prolifera comprises primarily radial muscle fibers arranged in distinct rows, while in Sphaerodoropsis sp. the axial proboscis consists of longitudinal and circular fibers and radial fibers are lacking; (5) in M. prolifera, the proximal and distal sections of the two anteriormost pairs of dorsal cirri possess longitudinal myofilaments, which are separate from the body wall musculature; by contrast, all appendages in Sphaerodoropsis sp. do not; (6) both species have bracing muscles: in M. prolifera they are positioned above the longitudinal fibers, whereas in Sphaerodoropsis sp. they are uniquely positioned between longitudinal and sublongitudinal transverse fibers. These results do not support a sister-group relationship of Syllidae and Sphaerodoridae. In addition, Sphaerodoropsis sp. is yet another example in the list of polychaetes lacking typical circular muscles in the body wall.     

Scanning Electron Microscopy of Mouth Appendages in Six Species of Barnacles (Crustacea Cirripedia Thoracica)

The morphology and setation of mouth appendages (trophi) are investigated with scanning electron microscopy in the balanomorph barnacles Semibalanus balanoides, Balanus balanusand B. nubilusand in the pedunculate barnacles Pollicipes polymerus, P. cornucopiaand Lepas anatifera.It is difficult to uphold a clearcut distinction between denticles and setae and several types of setae also intergrade with each other. The trophi of Pollicipes polymerusand P. cornucopiahave the most ‘generalized’ morphology. The palps of Pollicipesand L. anatiferaare simpler than those in balanomorphs and carry a single type of seta. In L. anatiferathe mandibles and maxillules are adapted to a semi-predatory feeding habit by carrying large, pointed teeth, but this species lacks the foliate-serrate setae which populate the palps in the other species studied. Compared with Pollicipesand Lepas, the three balanomorphs have palps with a complex setation. The trophi in S. balanoidesdiffer from the two species of Balanusin numerous features of setation and denticulation, notably in having the palps populated by plumodenticulate setae homologous to purely denticulated types in Balanus.It is suggested that SEM studies of barnacle trophi will provide characters of use in estimating phylogeny.     

Catecholaminergic innervation of muscles in the hindgut of crustaceans

Summary The crustacean species Pacifastacus leniusculus and Gammarus pulex were investigated by electron microscopy in a search for possible neuromuscular junctions in the hindgut, which has a rich supply of catecholaminergic fibres. True neuromuscular synapses were found in both species between nerve terminals containing dense-core vesicles (80–110 nm in diam.) and muscle fibres. We suggest that the dense-core vesicle terminals contain a catecholamine, and this is supported by ultrahistochemical tests for monoamines. Two types of junctions are found: one in which the nerve terminal is embedded in the muscle cell (both species) and one in which protrusions from the muscle cell meet nerve terminals (Pacifastacus). Gammarus pulex, which has only circular muscles in the hindgut, has only catecholaminergic innervation, whereas Pacifastacus leniusculus has circular and longitudinal muscles both with at least two types of innervation.The investigation was supported by grants from the Swedish Natural Science Research Council (B 2760-009), the Hungarian Academy of Sciences, the Royal Swedish Academy of Sciences, and the Magnus Bergvall Foundation. We are also indebted to Mrs. Lena Sandell for her skilful technical assistance     

Ontogeny of the jaws of monogonont rotifers: the malleate trophi of Rhinoglena and Proalides (Ploima,Epiphanidae)

Information on the embryonic development of the malleate trophi in Epiphanidae (Rotifera, Monogononta, Ploima) is presented, based on scanning electron microscopy observations in Rhinoglena fertoeensis, R. frontalis, R. kutikovae, R. tokioensis, and Proalides tentaculatus, to contribute to the understanding of this structure of high evolutionary and functional relevance in Rotifera. The first observable and distinctly sclerotized structures were a double row of median transversal sclerites along the longitudinal axis, wherein the future unci, rostellar scleropili, cristae rami, and basal apophyses became recognizable. Fulcrum and manubria arose subsequently; the fulcrum sclerites were longitudinally ordered in a double layer. The rami chambers developed last as lamellar structures. Unci appeared as separate thin, elongate elements, the primary uncini, developing to uncus plates by transversal growth and apposition of sclerite material on the shafts of the uncini. The heads of the uncini showed their greatest development after fusion of their shafts into uncus plates. The interjacent spaces between the heads functioned as a mold, organizing bundles of sclerites which developed into the uniseriate, zigzag‐shaped cristae rami. The fulcrum attained its definite shape by elongation of the double layer of rod‐shaped sclerites into appressed sclerofibrillae. Manubria became visible as a proximal ridge of sclerites, whereupon a triangular lamella composed of crisscross‐oriented sclerites developed distally, growing out to the manubrial chambers. Ramus chambers originated from two longitudinal amorphous lamellae incorporating the median rami sclerites and closing from distal to proximal; subbasal chambers were formed before the basal chambers.     

Gross anatomical and histomorphological features of the Acanthopagrus schlegelii digestive tract (Bleeker 1854) Perciformes,Sparidae

Acanthopagrus schlegelii is an autochthonous teleost species concerning the remarkable economic importance and prevalent fish cultivated in China as well as in different nations of South-East Asia. Little is known about the digestive tract (DT) morphology of A. schlegelii. Therefore, anatomical and histomorphological aspects of A. schlegelii DT were examined by light and scanning electron microscope (SEM). Anatomically, DT of A. schlegelii was mainly formed of oesophagus, well-developed stomach and fingers like pyloric caeca (four in number), intestinal regions and rectum. Histomorphologically, oesophagus occurred as a shorter tube-like organ presenting a longitudinal folded mucosa that connects oropharynx cavity to stomach. Stomach was a muscular thick-wall organ that included three regions, thickly longitudinal folds were observed in the first (cardiac) and last (pyloric) regions, whereas the second (fundic) region showed folds in different directions. Long villi were observed within pyloric caeca and anterior intestine. Tunica muscularis appeared narrow in the anterior intestine, whereas thicker in the posterior part of the intestine. Collectively, anatomical and histomorphological aspects of A. schlegelii DT are consistent with the carnivorous habit of this species. These data could be a potential source to modify better methods of nutrition and identify the DT pathogenic conditions in farming of this fish.     

Revisiting the Cephalodella trophi types

The six trophi types proposed by Wulfert (Archiv für Hydrobiologie 31:592–636, 1937) are used as one main character to identify Cephalodella species, although these trophi types were just based on the trophi of 31 species described after light microscopy findings. Given the 160 species nowadays valid and the possibility of examining trophi with scanning electron microscopy it is questionable if the definitions of the six types might or rather have to be improved in order to facilitate species identification. Here, a new even simpler definition scheme is proposed to identify the six trophi types.