Characterization of the initial ontogeny of Leiarius marmoratus (GILL, 1870): larvae to juvenile

Aiming to provide data on the biology of Leiarius marmoratus, which will aid in its production in captivity, as well as in studies for its preservation in the environment, this work had as objectives: analyze and describe main morphological alterations during larval ontogeny of the species. We analyzed 205 individuals, obtained by induced reproduction (Colpani Pisciculture) and kept in CEPTA/ICMBIO, Pirassununga, São Paulo, Brazil. Analyses were performed from hatching moment to 30th day. The specimens were classified into two periods: larval (Stages: vitelline, pre‐flexion, flexion, post‐flexion) and juvenile. Hatched larvae showed ident chromatophores only at anterior and posterior extremities of yolk sac. The standard length ranged from 2.16 mm (yolk) to 28.84 mm (Youth). Dorsal fin rays were initially observed at flexion stage (12–14 rays). Major alterations occurred during post‐flexion/juvenile stage, when dorsal, pectoral, pelvic, anal, and caudal fins were observed and pigmentation intensified throughout the lateral region, forming bands in the body, one between the end of the head and beginning of dorsal to pelvic fin, and another one beginning at dorsal to caudal peduncle and four longitudinal at the head.     

Morphological and histochemical features of the digestive tract of Leiarius marmoratus (Gill, 1870)

Leiarius marmoratus, a freshwater catfish from Pimelodidae family, shows great biological and commercial relevance because of its geographic distribution and adaptation to fish-farm. The knowledge of the morphological characteristics of the digestive tract is fundamental to the understanding of fish physiology and nutrition, which helps in the planning of diets to provide better management and success in fish farming. Thus, this work described the morphology and histochemistry of the digestive tract of L. marmoratus adults. After euthanasia, the animals were dissected for analysis of the digestive tract. The oesophagus is a short and distensive organ with longitudinal folds that allow the passage of large food, e.g., other fishes. Oesophageal mucosa layer shows a stratified epithelium with goblet cells and club cells. The secretion of goblet cells is composed of neutral and acidic mucins that are anchored in the epithelium luminal face by epithelial cells fingerprint-like microridges, lubricating the surface to facilitate the food sliding. Club cells have protein secretion that can be involved in alarm signals when epithelium is damaged and in immunological defence. The saccular stomach is highly distensible to store large food. Gastric mucosa layer is composed of epithelial cells with intense secretion of neutral mucin to protect against self-digestion of gastric juice. Cardiac and fundic regions of stomach show well-developed gastric glands composed of oxynticopeptic cells. These cells have numerous mitochondria, highlighting their intense activity in the synthesis of acid and enzymes. The intestine is divided into three regions: anterior, middle and posterior. Although it is a short tube, intestine shows longitudinal folds and microvilli of enterocytes to increase the contact surface. These folds are higher in the anterior region of the intestine, highlighting their function in digestion and absorption. Intestinal goblet cells have acidic and neutral mucins that lubricate the epithelium and aid in digestive processes. These cells increase in number towards aboral, and they are related to the protection and lubrication to expulsion of faecal bolus.     

Reproductive biology of Pseudoplatystoma corruscans (Spix and Agassiz, 1829) and Pseudoplatystoma reticulatum (Eigenmann and Eigenmann, 1889), two species of fisheries importance in the Cuiabá River Basin,Brazil

The aim of this study was to compare the reproductive processes of two large catfishes, Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum, from the Cuiabá River Basin. The reproductive process were assessed to: (i) characterizing the population structure and sex ratio; (ii) determining the reproductive period; (iii) estimating and quantify the nutritional status and energy reserves and their relationships with reproductive stages; and (iv) estimating the body length at first gonad maturation (TL₅₀). Individuals were sampled monthly from July 2006 to February 2008 using gill nets, seine nets, hooks, casting nets and trotlines. In addition, 294 individuals were obtained from the artisanal fishery in the city of Cuiabá, Mato Grosso state, Brazil. Total lengths were greater for females for both species, with no significant difference in the sex ratio; growth was considered isometric, except for P. corruscans males. Peak reproductive activity was in December and January. Differences in the hepatosomatic index (HSI) in P. corruscans depended on the gender. In P. reticulatum the HSI did not differ between sexes or among developmental stages. For P. corruscans, the estimated mean total length at first maturity (TL₅₀) was 62.92 cm, and for P. reticulatum 57.84 cm. Action to ensure the protection of the fish stocks should consider their reproduction processes, which are important for the equilibrium of these populations in the Cuiabá River, as well as for fisheries management.     

Development of the osteocranium in Corydoras aeneus (Gill, 1858) Callichthyidae,Siluriformes

Development in the osteocranium of Corydoras aeneus was studied based on 48 cleared and stained specimens and 10 series of serial sections. Development overall follows the general trends observed in siluriform development, with ossifications appearing as a response to functional demands. Early development of the skull occurs in two distinct phases. In a first phase, several new bony elements, all of dermal origin and related to feeding, appear shortly after yolk depletion (4.4 mm SL). Between 5 and 8 mm SL, developmental priorities seem to shift to size increase of the cartilaginous skull and no new bony elements appear. Finally, a second phase of osteogenesis occurs from 8 to 18 mm SL, in which all remaining dermal and perichondral bones appear. J. Morphol. 2011. © 2011 Wiley‐Liss, Inc.     

The ontogeny of Loxoconcha japonica Ishizaki, 1968 (Cytheroidea, Ostracoda, Crustacea)

The ontogeny of the cytheroidean species Loxoconcha japonica is documented from the earliest instar to the adult. The first instar (instar A-8) of L. japonica is different from that of cypridoidean species in that it has an additional appendage, the furca, present. From instar A-7 onwards, the appearance of the appendages is similar to that of cypridoidean and bairdioidean species. The furca is well developed in instars A-8 to A-5, and is probably an important appendage in these early instars, despite its reduced form in the adults. Some appendages of L. japonica (e.g. the antennae) gain very few setae and claws through ontogeny, compared with species from other superfamilies. This possibly reflects paedomorphic evolution of this species.     

Post-weaning cranial ontogeny in two bandicoots (Mammalia,Peramelomorphia, Peramelidae) and comparison with carnivorous marsupials

The ontogeny of the skull has been studied in several marsupial groups such as didelphids, microbiotheriids, and dasyurids. Here, we describe and compare the post-weaning ontogeny of the skull in two species of bandicoots, Echymipera kalubu (Echymiperinae) and Isoodon macrourus (Peramelinae), analyzing specific allometric trends in both groups, describing common (and specific) patterns, and discussing them on functional and phylogenetic grounds. Growth patterns were analyzed both qualitatively and quantitatively, including bivariate and multivariate analyses of allometry. We also evaluated character transformation and phylogenetic signals of the allometric patterns in several groups of marsupials and some placentals. We identified morphological changes between juvenile and adult stages in both species of peramelids, many related to the development of the trophic apparatus. Notable differences were detected in the patterns of growth, suggesting divergences in ontogenetic trajectories between both species. Both bivariate and multivariate methods indicate that positive allometries in E. kalubu apply to longitudinal dimensions, whereas in I. macrourus, positive allometries are restricted to vertical dimensions of the skull. The comparison of the allometric trends of two bandicoots with previously studied taxa reveals that although peramelids exhibit a particularly short gestation period and divergent morphology compared to other marsupials, their pattern does not show any particular trend. Some allometric trends seem to be highly conserved among the species studied, showing weak phylogenetic signal. Marsupials in general do not show particular patterns of post-weaning skull growth compared with placentals.     

Life habit and ontogeny of the unusual arcid bivalve Ambrogia mytiloides (Brocchi, 1814)

The unusual Plio-Pleistocene arcid Ambrogia mytiloides (Brocchi, 1814) has a large, elongate, smooth and streamlined shell. On the basis of these characters and the occurrence of moderate shell torsion, the mode of life of this species was formerly thought to be semi-infaunal endobyssate, obliquely oriented like the twisted arcid Trisidos. The discovery of shells in life position suggests that this species lived in a subvertical position. Rather than a recliner, this arcid was then a sticker, whose stability was provided by the byssus, which also was used to aid the bivalve in burrowing, and by its large size. The morphology of juvenile valves, smaller than 4 mm, suggests an epibyssate mode of life in its early growth stages. Ambrogia represents a remarkable pathway in the secondary return of arcids to soft bottoms: with this genus, they reached their deepest burrowing level. However, this strategy was not very successful, probably because of evolutionary constraints on the Arcoida.     

The ontogeny of the cypridid ostracod Eucypris virens (Jurine, 1820) (Crustacea,Ostracoda)

The chaetotaxy (shape, structure and distribution of setae) of appendages and valve allometry during the post embryonic ontogeny of the cyprididine ostracod Eucypris virens are described. It is shown that the basic ontogenetic development of E. virens is very similar to that of other species of the family Cyprididae. During ontogeny, the chaetotaxy shows continual development on all podomeres of the limbs with the exception of the last podomere on the antennulae. The long setae on the exopodite and protopodite of the antennae have a natatory function until the actual natatory setae develop in later instars. Aesthetascs (presumed chemoreceptors) ya and y3 are the first to develop and may have an important function in the first instars. Cyprididae require a pediform limb in the posterior of the body presumably to help them to attach to substrates and this is reflected by the pediform nature of one limb at all times throughout all instars. This study has also shown that the fifth limb is most probably of thoracic origin and hence ostracods have only one pair of maxillae.     

The ontogeny of the entocytherid ostracod Uncinocythere occidentalis (Kozloff & Whitman, 1954) Hart, 1962 (Crustacea)

The Entocytheridae is a cytheroidean family that is known for its commensal mode of life on other crustaceans. However, due to their small size and large sexual dimorphism in the sizes of the carapace, the ontogeny of the entocytherids is poorly understood. This paper documents the basic body plans and pore systems of the entocytherid Uncinocythere occidentalis (Kozloff & Whitman, 1954) Hart, 1962 through ontogeny and compares them with other podocope groups. U. occidentalis has seven juvenile stages, one less than other cytheroidean groups. The general appearance of the limbs during the ontogeny of U. occidentalis is similar to that of other podocope ostracods, such as Limnocythere inopinata (Cytheroidea) Loxoconcha japonica (Cytheroidea),Eucypris virens (Cypridoidea), and Neonesidea oligodentata (Bairdioidea) with the exception of the maxillula. The adult maxillula of U. occidentalis is reduced to just a palp and third masticatory lobe (endite), and the third masticatory lobe and branchial plate of this appendage form later in the ontogeny compared with other podocope species (i.e., these features show post displacemental ontogenetic development). The number of the pore systems of the earliest juvenile (A-7) of U. occidentalis is 10, and is different from that of the corresponding stage of other cytheroidean groups which have 9. This fact, together with the different mode of development of the maxillula, indicates that the entocytherids are not only highly specialized to their commensal mode of life but that they are also phylogenetically distant from most other cytheroidean families, possibly differentiating from the others during the early evolution of the cytherids.     

First record of non‐native hybrid catfish Pseudoplatystoma reticulatum × Leiarius marmoratus in the Upper Paraná River basin,Brazil

The aim of this study is to report the presence of a three non‐native hybrid long‐whiskered catfishes (family Pimelodidae) in the Upper Paraná River basin, Brazil. Genetic analyses demonstrated that the three presumptive hybrids were a result of the crossbreeding of Pseudoplatystoma reticulatum (central Amazonas River basin and Lower Paraná River) and Leiarius marmoratus (Amazonas, Essequibo and Orinoco rivers), producing a hybrid commonly known in Brazil as cachandiá. The potential threat to biodiversity, due to possible genetic contamination, competition and predation of wild stocks, of such artificially produced hybrid fishes is discussed.     

Cytogenetic characterization of F1, F2 and backcross hybrids of the Neotropical catfish species Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum (Pimelodidae, Siluriformes)

The cytogenetic characteristics of Pseudoplatystoma corruscans and Pseudoplatystoma reticulatum and their F1, F2 and backcross hybrids were assessed by using chromosome banding techniques. The diploid number of 56 chromosomes was constant in all species and lineages, with a karyotypic formula containing 20 metacentric, 12 submetacentric, 12 subtelocentric and 12 acrocentric chromosomes. Nucleolar organizer regions (NORs) were identified in two subtelocentric chromosomes in the parents and hybrids, with partial nucleolar dominance in F1 and F2 specimens. Heterochromatic blocks were detected in the terminal and centromeric regions of some chromosomes in all individuals. For parental and hybrid lineages, 18S ribosomal clusters corresponding to NORs and 5S ribosomal genes were identified in distinct pairs of chromosomes. The striking conservation in the chromosomal macrostructure of the parental species may account for the fertility of their F1 hybrids. Similarly, the lack of marked alterations in the chromosomal structure of the F1 hybrids could account for the maintenance of these features in post-F1 lineages.     

Ontogeny of the chondrocranium in Corydoras aeneus (Gill, 1858) (Callichthyidae, Siluriformes)

Callichthyids take a basal position in the loricarioid evolutionary lineage leading up to an algae scraping feeding mechanism in the loricariid family. Therefore, the study of the morphology and development of a callichthyid representative would contribute to a better knowledge on the differences in cranial morphology and their impact on feeding ecology within this superfamily. Therefore, development in the chondrocranium of Corydoras aeneus was studied based on 22 cleared and stained specimens and 6 series of serial sections. The latter sections were also digitized and used for 3D reconstructions. Development overall follows the typical siluriform trends in chondrocranial development. Even the low complexity of the chondrocranium at hatching fits the trend observed in other siluriforms, although other studies showed loricarioid hatchlings to generally show more complex chondrocrania. In contrast to other catfish, in C. aeneus, the notochord was never found to protrude into the hypophyseal fenestra. In addition, also differing from other siluriforms, a commissura lateralis is present, a state also reported for Ancistrus cf. triradiatus (Geerinckx et al., [2005] J Morphol 266:331-355). The splanchnocranium again has the typical siluriform shape during its ontogeny, with the presence of a compound hyosymplectic-pterygoquadrate plate, although not fused to the neurocranium or interhyal at any time during ontogeny, a state described earlier for Callichthys callichthys (Hoedeman, [1960a] Bull Aquat Biol 1:73-84; Howes and Teugels, [1989] J Zool Lond 219:441-456). The most striking difference found in comparison to other catfishes, however, involves thebranchial basket, which arises as a single element with a further differentiation from the middle arches on in both a rostral and caudal direction.     

Speciation within blidingia minima (chlorophyta) in japan: evidence from morphology, ontogeny, and analyses of nuclear rdna its sequence

The genus Blidingia is a common, sometimes abundant, component of northern hemisphere temperate and subarctic shores. Species determination relies on characteristic differences in morphology and early ontogenic development. Within the species Blidingia minima (Naegeli ex Kuetzing) Kylin in Japan, however, there appear to be three distinct types, the F-, D-, and M-types, which are differentiated in early ontogeny. The M-type can be further categorized into three subtypes. Results of intensive field and culture studies supported the view that morphological characteristics do not reliably separate the F-, D-, and M-types and that all three may potentially cross breed. The F-type has characteristics in early ontogeny of the species B. chadefaudii (  J. Feldmann) Bliding in European waters and this, combined with the morphological and cross breeding studies, suggest that B. chadefaudii should be merged with B. minima. In this study, molecular analyses of nuclear rDNA from samples of the F- and D-types indicated that both have a distinctive and characteristic identity. Sequence data also examined from two of the M-type subtypes indicated that each of these also has a characteristic molecular identity clearly distinguished from that of the F- and D-types. Analyses indicated that there is a close relationship between the D-type and one of the M-type subtypes, and that these are more closely related to the F-type than to the other M-type examined. Comparison with studies of this gene region in other ulvophytic algae indicated a wide range of variation within B. minima. Such variation may be useful in assessing distribution patterns in Japanese waters of the developmental types within this species.     

Larval and post-larval development of the branchiopod clam shrimp Cyclestheria hislopi (Baird, 1859) (Crustacea, Branchiopoda, Conchostraca, Spinicaudata)

The larval and post-larval development of Cyclestheria hislopi is examined by SEM. There are at least nine stages (excluding the adult) – six larval and three post-larval stages. The first four stages are passed within the egg-membrane. The larval and the post-larval phase are separated by a profound change in morphology that takes place between stages VI and VII. The larva shifts from a dorso-ventrally flattened 'larval' appearance up to stage VI to a laterally flattened, more 'adult' appearance from stage VII. New morphological data have been revealed by this study, including (1) a large and globular larval dorsal organ; (2) the carapace starts its development from the segments of the first and second maxillae; (3) the anterior ramus of the second antenna in adult Cyclestheria hislopi is the endopod, and the posterior ramus the exopod. Direct development of the brood in Cyclestheria hislopi – unique among conchostracans – is compared with that of the Cladocera. If Cyclestheria is the sister group to the Cladocera, as favoured in this work, the classical neoteny theory of the Cladocera must be reconsidered, as there is no particular similarity between any adults of the Cladocera and any of the larval stages of Cyclestheria . It is suggested that Cyclestheria displays the type of development present in a cladoceran ancestor. A comparison between Cyclestheria and the Upper Cambrian 'Orsten' fossil Rehbachiella kinnekullensis reveals a remarkable similarity in the endite morphology of the trunk limbs.     

中国的长鼻三趾马(Proboscidipparion)和近三趾马(Plesiohipparion)个体发育的形态学研究及其欧亚与非洲亲缘种的观察（英文）

分析了来自贺风近三趾马(Plesiohipparion houfenense)、原始长鼻三趾马(Proboscidipparion pater)和中国长鼻三趾马(Proboscidipparion sinense)三个种的共计18颗经过切片处理的颊齿,总结了颊齿在个体发育过程中的形态变化,并揭示出这些中国类群与其他欧亚大陆以及非洲的三趾马门类之间可能存在近裔共征。在形态特征上,Pl.houfenense的上下颊齿很可能与西班牙的Pl.crusafonti,土耳其的Plesiohipparion aff.P.huangheense以及非洲的Eurygnathohippus类群有共同特征。另一方面,这些欧亚大陆和非洲类群事实上很可能起源于西瓦利克的Sivalhippus类群。Proboscidipparion属中的两个种,P.pater和P.sinense之间有着明显的亲缘关系,并且可能与土耳其的"Proboscidipparion"heintzi也有亲缘关系。另外,以前的学者曾提出Proboscidipparion与Sivalhippus支系存在亲缘关系,本文对P.pater和P.sinense上、下颊齿的分析支持了这一观点。     

Comparative ontogeny of perfect and pistillate florets in Senecio vernalis (Asteraceae)

We studied the inflorescence, and in particular ontogeny and development of the florets in Senecio vernalis as a representative member of Asteraceae, using epi-illumination microscopy. Initiation and subsequent development of florets on the highly convex inflorescence apex occur acropetally, except for pistillate ray florets, which show a lag in initiation. Receptacular bracts derive from the receptacular surface after development of all florets. The order of whorl initiation in both disc and ray florets include corolla, androecium and finally the pappus, together with the gynoecium. Development of corolla lobes from a ring meristem occurs in bidirectional order starting from the lateral side, whereas stamens incept unidirectionally from the abaxial side. Concurrently with the inception of two median carpel primordia, a ring meristem develops at the base of the corolla from which pappus bristles differentiate in later stages. Pistillate ray florets show significant differences from perfect disc florets as reflected by the zygomorphic shape of the floral apex and a shift of floral merosity from pentamery to tetramery. Loss of stamens in ray florets occurs due to abortion of primordia after initiation.     

Oral ontogeny of the Ayu, Plecoglossus altivelis and comparisons with the jaws of other salmoniform fishes

The Japanese Ayu, Plecoglossus altivelis Temminck & Schlegel is the sole representative of the salmoniform family Plecoglossidae. The Ayu is remarkable for its dentition which in adults comprises groups of diagonally arranged comb-like teeth in the outer tissue of the jaws. In juveniles (below 63 mm SL) the teeth are attached normally to the jaws. The transition of tooth form is correlated with a switch from zooplanktivory to algal or aufwuchs grazing. The present study follows the development of the teeth, jaws, oral cavity ethmoid and suspensorial elements in specimens ranging in size from 41–70 mm SL. The possible mode of function of the adult dentition is discussed. Comparisons are made with the jaws of other salmoniform fishes and a suite of supposed apomorphic characters are identified which are also shared with certain genera of the family Osmeridae, thus supporting the ideas of others that the Osmeridae is a paraphyletic assemblage.     

Morphology,ontogeny and affinities of the Hirnantian triplisiid brachiopod Streptis undifera from Baltoscandia

New silicified topotypic material of the Upper Ordovician Streptis undifera (Schmidt, 1858) from the stratotype of the Porkuni Regional Stage in Estonia provides important data on triplesiid morphology and ontogeny, which has substantial implications for our understanding of the affinity of this group of brachiopods. In particular, the new material shows that the early ontogeny of Streptis includes evidence for a cicatrix attachment and colleplax‐like structure in the ventral valve. It is likely also that a lecithotrophic feeding habit evolved in triplesiidines sometime in the Ordovician, which sets them apart from all other known strophomenates. A neotype is selected among the specimens of Streptis undifera from the type locality in Porkuni. In Baltoscandia, Streptis undifera appears first in Norway in late Katian below the strata with the pentamerid brachiopod Holorhynchus. In Estonia, Streptis undifera is an index species of the early Hirnantian and occurs in association with stromatoporoid‐coral reefs and related inter‐reef deposits, which overly the strata with Holorhynchus. In Baltoscandia, the distribution areas of Streptis and Holorhynchus are more or less identical in spite of some differences in age.     

Hormonal correlates of ontogeny in baboons (Papio hamadryas anubis) and mangabeys (Cercocebus atys)

This study investigates the relationship between serum hormone levels and morphometrics during ontogeny in olive baboons (Papio hamadryas anubis) and sooty mangabeys (Cercocebus atys), to test hypotheses about the endocrine regulation of species size differences. First, we expect that levels of hormones and binding proteins predict size change during ontogeny in both species. Second, a high level of integration among the hormones and binding proteins analyzed is expected, with the implication that they act in combination to influence the development of body size and shape. Utilizing a mixed longitudinal sample, we compare change in 18 different measurements, which reflect overall size growth as well as growth in length and circumference, with levels of six growth-related hormones and binding proteins. We examine the relationship between hormone and binding protein levels and morphometrics, using multivariate analyses and "arithmetically-estimated" velocity curves of hormones, binding proteins, to characterize how the endocrine factors analyzed relate to growth. Results suggest that levels of these endocrine factors can be used to predict local and overall growth during ontogeny and that integration between multiple hormone axes is indicated. While important for growth in both species, ontogenetic changes in hormone and binding protein levels are more tightly correlated with changes in morphometric measurements in baboons than mangabeys. These results have important implications for understanding why some smaller-bodied species have higher absolute growth-related hormone levels than larger-bodied species.