Comparative oocyte morphology and fecundity of five characid species from São Francisco River basin,Brazil

The morphology of vitellogenic oocytes and the batch fecundity of five tropical forage species belonging to the family Characidae, were studied in 104 late‐maturing ovaries. Significant morphological differences between vitellogenic oocytes and ovarian follicles were found. The lowest batch fecundity values were recorded in Hemigrammus marginatus (480 ± 163) and Orthospinus franciscensis (1701 ± 562), which were the smaller species in terms of total length, body weight and oocyte diameter. The highest batch fecundity value was observed in Tetragonopterus chalceus (8384 ± 3944) having the highest GSI and oocyte diameter. Batch fecundity and gonad weight was highly correlated followed by body weight and total length. Relative fecundity was estimated per unit total length, body weight and gonad weight. The wide variation in fecundity observed between the specimens and the species analysed is possibly related to the multiple spawning reproductive strategy of these fishes. Since T. chalceus have higher values of batch and relative fecundity, it is concluded that this species has a higher reproductive potential than the other forage species studied.     

Comparative morphology of the oocyte surface and early development in four characiformes from the São Francisco River,Brazil

Early development from the egg fertilization to complete resorption of the yolk‐sac is a critical period in the life cycle of teleost fish. Knowledge of this process provides essential parameters for aquaculture and identification of spawning sites in the wild. In the present study, a comparative morphological analysis of the oocyte surface as well as early development was performed in four commercially valuable species from the São Francisco River: Brycon orthotaenia, Leporinus obtusidens, Prochilodus argenteus, and Salminus franciscanus. Stripped oocytes, embryo, and yolk‐sac larvae were analyzed by scanning electron microscopy (SEM) and histology. A set of 10 lectins was used for investigation of lectin‐binding pattern in oocytes. In the four species, the outer layer of the zona radiata reacted to most lectins, indicating complex polysaccharides at the oocyte surface while no reactivity was detected in the inner zona radiata and yolk globules. Typical structural arrangements were recognized at the micropylar region by SEM. The four species showed nonadhesive eggs, short embryonic period (18–20 h at 24 ± 1°C), and poorly developed larvae at hatching. At 24 h posthatching (hph), larvae of the four species had neuromasts on the body surface. Rudimentary cement glands for larval attachment were identified on the cephalic region at 24 and 48 hph in B. orthotaenia and S. franciscanus, and following they were in regression. The time for whole yolk resorption varied among species from 48 to 120 hph, occurring earlier in S. franciscanus, followed by B. orthotaenia, P. argenteus, and L. obtusidens. The formation of the digestive tract and the mouth opening indicated initiation of exogenous feeding 24 h before complete resorption of the yolk. Together, our data indicate similarities in the early development among species that may be related to the life cycle strategies and phylogeny. J. Morphol. 276:1258–1272, 2015. © 2015 Wiley Periodicals, Inc.     

Epigean and subterranean ichthyofauna from the São Domingos karst area, Upper Tocantins River basin, Central Brazil

In a survey of epigean and cave streams in the São Domingos karst area, 38 species were present in the stream reaches, including 10 characiforms, 19 siluriforms, seven gymnotiforms and two perciforms. One species of Astyanax and the new armoured catfish species Parotocinclus were the most common epigean fishes in São Domingos. The most conspicuous non-troglomorphic cave fishes were Hoplerythrinus unitaeniatus , Astyanax sp., Brycon sp. and two species of Imparfinis , with I. hollandi being the most common fish in most caves. São Domingos karst area has the most diverse and abundant Brazilian cavefish fauna, not only in terms of troglobitic species but also in general fish richness, with 22 non-troglomorphic species recorded in caves in addition to five troglobitic ones. Most fishes examined for stomach contents had at least partially full stomachs. The studied fishes were carnivorous, feeding primarily on aquatic insects. Fishes with developed gonads recorded in caves were I. hollandi , Rhamdia quelen , Pseudocetopsis plumbeus , Hoplerythrinus unitaeniatus and Cichlasoma araguaiensis , indicating a potential for reproduction in the subterranean habitat.     

Prolongation of somitogenesis in two anguilliform species,the Japanese eel Anguilla japonica and pike eel Muraenesox cinereus,with refined descriptions of their early development

The embryonic development of the Japanese eel Anguilla japonica and pike eel Muraenesox cinereus was morphologically investigated with laboratory‐reared specimens to clarify the characteristics of somitogenesis. In A. japonica, somites were first observed at 18 h post fertilization (hpf) when epiboly reached 90%. Somitogenesis progressed at a rate of 1·6 h^?1 at mean ± s.d . 22·6 ± 0·7° C and completed at 107 hpf (3 days post hatching; dph) when total number of somites (ST) reached 114, which corresponds to the species' number of vertebrae (112–119). In M. cinereus, somites were first observed at 14 hpf when epiboly completed. Somitogenesis progressed at a rate of 1·9 h^?1 at mean ± s.d . 24·4 ± 0·2° C and completed at 90 hpf (2 dph) with 149 ± 4 ST, which corresponds to the species' number of vertebrae (142–158). Both species hatched before somitogenesis was completed, at 37 hpf with 47 ST and 42 hpf with 82 ± 4 ST, respectively. The formation of other organs such as the heart, mouth and pectoral fin bud occurred during somitogenesis. Comparison with the development of zebrafish Danio rerio indicates a prolongation of somitogenesis in A. japonica and M. cinereus. Their somitogenesis rates, however, correspond well with that of D. rerio estimated at the same temperature and their developmental stages at hatching are almost equivalent to other fishes having similar yolk sizes. Therefore, the prolongation of somitogenesis in A. japonica and M. cinereus may be accounted for solely by the increased numbers of somites to be formed, not by a slow somitogenesis rate or an acceleration in organogenesis.     

Observations on the seasonal breeding biology and fine structure of the egg surface in the white piranha Serrasalmus brandtii from the São Francisco River basin,Brazil

In the Juramento Reservoir, south‐eastern Brazil, the white piranha Serrasalmus brandtii showed a prolonged reproductive season, with evidence for multiple spawning and a reproductive peak associated with seasonal rains. The egg surface exhibited a honeycomb‐like pore canal arrangement and an adhesive apparatus surrounding the micropyle. Electron microscopic analysis suggests a role for the micropylar cell and neighbouring follicular cells in secretion of substances for egg attachment.     

Hisonotus devidei,a new species from the São Francisco basin,Brazil (Siluriformes: Loricariidae)

A recent expedition to headwaters of the Rio Pandeiros, a left‐bank tributary of the Rio São Francisco revealed the presence of a fourth species of Hisonotus from that basin. Hisonotus devidei sp. nov. differs from congeners by the presence of conspicuous dark blotches of distinct shapes irregularly arranged along lateral and dorsal surfaces of the body and scattered throughout all fins, by possessing small plates in lateral portions of the abdomen and adjacent areas between pelvic fins without development of dermal plates and by morphometric ratios. The putative phylogenetic placement of the new species is discussed based on morphological comparisons with species of related Hypoptopomatinae genera and the Hisonotus species diversity within the Rio São Francisco Basin is compared with that of adjacent basins.     

Comparative analysis of gonadal morphology in six fish species of the Incertae Sedis genera in Characidae of occurrence in the São Francisco River Basin,Brazil

Martins, Y.S., Arantes, F.P., Sato, Y., dos Santos, J.E., Rizzo, E. and Bazzoli, N. 2012. Comparative analysis of gonadal morphology in six fish species of the Incertae Sedis genera in Characidae of occurrence in the São Francisco River Basin, Brazil. —Acta Zoologica (Stockholm) 93 : 48–56. This study presents a comparative analysis aiming to show the remarkable differences found in gonad morphology between six fish species from the genera Incertae Sedis in the Characidae family. Maturing ovaries of Astyanax fasciatus presented grayish color whilst the other species’ were yellowish in color. The cortical alveoli of the analyzed species are small (5.20 ± 1.44–8.28 ± 2.02 μm) and are formed by various discontinuous layers of vesicles except in the Bryconops affinis, where they are large (12.87 ± 2.41 μm) and form various continuous layers of vesicles. The pellucid zone is thin and varies from 2.44 ± 0.90 to 5.79 ± 1.90 μm and is thickest in B. affinis (10.57 ± 2.08 μm). Folds in the pellucid zone were observed in Astyanax bimaculatus, A. fasciatus, Hemigrammus marginatus, and Moenkhausia costae. The follicular cells of B. affinis are columnar (28.19 ± 13.71 μm), while they are squamous in other species (1.52 ± 0.64–2.12 ± 0.78 μm). This study showed that the morphologic and biometric characteristics of the B. affinis vitellogenic oocytes are statistically different than the analyzed other ones Incertae Sedis of the Characidae family. In advanced maturing testis of A. bimaculatus and A. fasciatus, the spermatozoa were embedded in acidophilic secretion which was gradually reabsorbed in the seminiferous tubules when males were partially spent.     

Length–weight relationships of two catfish species from the Guareí River basin,São Paulo,Brazil

Here the length–weight relationships (LWRs) of two catfish species are provided. Individuals of Imparfinis mirini Haseman, 1911, and Phenacorhamdia tenebrosa (Schubart, 1964) were collected in August and December 2017 from the Guareí River Basin, upper Paraná River basin, Brazil. Values of b were between 2.66 and 3.11 and a between 0.0122 and 0.0137; statistical analysis showed high r² values. Lastly, a new record of maximum standard length for P. tenebrosa is provided.     

Ultrastructure of oocyte maturation,fertilization, and early embryo development in vitro in the Siberian tiger (Panthera tigris altaica)

The application of assisted reproduction techniques to wild cats has been stalled by a lack of basic knowledge of the reproductive biology in these species. In this study, the ultrastructure of Siberian tiger (Panthera tigris altaica) cumulus-oocyte-complexes (COCs), as well as in vitro produced (IVP) zygotes and embryos were investigated, to estimate the normality of the manipulated reproduction processes. Adult female tigers were subjected to a purified porcine pFSH/pLH stimulation treatment followed by oocyte aspiration. According to morphological appearance at the stereomicroscopical level, COCs were classified as mature, immature, or degenerated, and then allocated into the following groups: presumptively immature COCs, which were in vitro matured (IVM-group) before fixation; presumptively mature COCs, which were either fixed after retrieval (pre-IVF-group), following in vitro insemination (IVF-group) or following in vitro insemination and subsequent in vitro culture (IVC-group). All specimens were processed for light and transmission electron microscopy (TEM). Both the IVM- and pre-IVF-group included oocytes in meiotic stages ranging from prophase I to metaphase II, and some prophase I oocytes in the IVM-group were apparently in their growth phase. The IVF-group presented features of presumptive normal fertilization, but aberrations such as polynucleation were also noted. The IVC-group included cleavage stage embryos of which, however, many were polynucleated. In conclusion, the procedures used for stimulation, aspiration, and classification of COCs resulted in retrieval of a heterogeneous population of oocytes which, following IVF and IVC, displayed a high rate of developmental deviations.     

Comparative ultrastructural studies of the zona radiata of marine fish eggs in three genera in Perciformes

The eggs of Mugil cephalus were significantly larger than those of Epinephelus malabaricus , and E. coioides , while those of Sciaenops ocellatus were intermediate between E. coioides and M. cephalus . The distribution density of pores in the egg envelope of S. ocellatus was significantly different from that of E. malabaricus and E. coioides . The micropyle diameters were significantly different in the four species. The ultrastructure of the zona radiata surface, the distribution density of pores and the size of eggs were also useful characters for distinguishing among the four species, but the ultrastructural features of the micropyles were the most important of all for egg identification.     

Relationship between oocyte morphology and reproductive strategy in loricariid catfishes of the Paraná River, Brazil

Relationships between ovarian structure, oocyte structure/development, and parental care/life history strategies of six loricariid catfishes common in the upper Paraná River, Brazil were examined with analysis of catch data, relative gonad weight, histology, and microscopy. Three life history strategies were observed. Loricariichthys platymetopon , Loricariichthys sp. And Loricaria sp. produce several small clutches of large eggs over a protracted spawning period. Males of these species guard their eggs and larvae, which are transported as a mass on the ventral surface of the male's body. Hypostomus ternetzi and Megalancistrus aculeatus produce the largest mature eggs and the smallest clutches relative to adult mass. The spawning periods of these species are short, and males guard their broods in excavations. Rhinelepis aspera has high fecundity, high relative mass of mature gonads (both sexes), small mature eggs, and broadcast spawning with no parental care. This species migrates to spawn over firm substrates in channel areas during a contracted period. Mature oocytes of external bearers had the thickest zona radiata, followed by the egg scatterer, and cavity nesters. The thickness of the zona radiata probably is an adaptation to protect the developing egg from injury from abrasion. The zona granulosa appeared to be associated with production of secretions responsible for egg adhesion, and this layer was thickest in mature oocytes of the cavity nesting species, followed by the external bearers. All six species have wide distributions in the Paraná River, tributaries, floodplain lagoons, and the Itaipu Reservoir, but brood guarders tended to be most common in lentic habitats.     

Comparative analyses of reproductive activity in Schizodon knerii (Steindachner, 1875) (Characiformes: Anostomidae) in three sections of the São Francisco River basin

This paper aims to establish possible changes in the main reproductive parameters of the so‐called piau‐branco, Schizodon knerii, in three sections of the São Francisco River basin. Fish (n = 388) were captured quarterly between May 2012 and April 2013 from three sections of the São Francisco River (SFR): section 1 = Três Marias Reservoir (TMR), a lentic environment; section 2 = SFR, the first 34 km downstream of TMR, a lotic environment in which the temperature, oxygen levels, and flow are not suitable for reproduction; section 3 = SFR, 34–54 km downstream from TMR after the confluence with the Abaeté River, a lotic environment in which temperature, oxygen levels and flow are suitable for reproduction. In section 2, females and males showed lower values of total length and body weight in relation to fish from sections 1 and 3. The reproductive mode of S. knerii in sections 1 and 3 exhibited a prolonged reproductive period, parceled spawning, and a reproductive peak from January to March. In section 2, neither spawning females or spermiated males were captured, probably due to the fact that this section receives cold water with low oxygen levels from the hypolimium of the dam that presents thermal stratification in the summer. This study showed in section 2, immediately downstream of the Três Marias Reservoir, that S. knerii does not reproduce successfully.     

Cytogenetic analysis of three sympatric Gymnotus (Gymnotiformes, Gymnotidae) species verifies invasive species in the Upper Paraná River basin, Brazil

Cytogenetic analyses were performed on three Gymnotus species, Gymnotus paraguensis , Gymnotus sylvius and Gymnotus pantanal , collected in sympatry in the region of Guaíra, Paraná State (Brazil). Gymnotus paraguensis presented 54 chromosomes (52m-sm + 2st) in both sexes, G. sylvius presented 40 chromosomes (36m-sm + 4a) in both sexes and G. pantanal presented 40 chromosomes (14m-sm + 26a) in females and 39 (15m-sm + 24a) in males, with an X₁X₁X₂X₂/X₁X₂Y multiple sex chromosome system. All three species had single nucleolar organizing regions and heterochromatin in the centromeric region of most chromosomes. Gymnotus pantanal , previously collected only in the Lower Paraná and Paraguay River basins, was confirmed for the first time in the Upper Paraná River basin. This species constitutes one of several examples of species that have colonized the region after flooding of the great Sete Quedas waterfalls by the construction of the Itaipu hydroelectric dam. The probable absence or infertility of hybrids is indicated by the high level of chromosome differentiation between these species.     

Pennsylvanian palynofloras from the Itu rhythmites (Itararé Subgroup, Paraná Basin) in São Paulo State, Brazil

The rhythmites of Itu present the best exposures of glacial varvites known in the Paraná Basin, and constitute a classic geological monument related to the Late Palaeozoic Gondwanan glaciation. Palynological results in this paper are based on rhythmites from two quarries in Itu area, central-eastern State of São Paulo, Brazil, including correlate levels of the “Itu Varvite Park”, as well as based on samples from the borehole IT-IG-85 (at 171 and 228 m) drilled also in the Itu City. Well-preserved indigenous miospores and microphytoplankton elements have been recorded. The former comprise 15 spore species and 19 pollen species, of which three are recorded for the first time in the Brazilian part of the Paraná Basin (Verrucosisporites cf. V. andersonii, Convolutispora archangelskyi and Caheniasaccites verrucosus). Microalgae include prasinophyceans (Leiosphaeridia sp., Tasmanites sp., Deusilites tenuistriatus), chlorophyceans (Botryococcus braunii) and zignemataceans (Tetraporina). The palynological content confirms a late Pennsylvanian (Kasimovian/Gzhelian) age for these rhythmites, which are assigned to the Crucisaccites monoletus interval Zone, based on the record of the eponymous pollen species and Scheuringipollenites maximus. Although very scarce, prasinophycean algae suggest low salinity marine conditions.     

Comparative morphology of the first instar of three species of Metopia Meigen (Diptera: Sarcophagidae, Miltogramminae)

The first instar larva is described for three species of the kleptoparasitic miltogrammine genus Metopia Meigen: M. campestris (Fallén), M. argentata Macquart and M. argyrocephala (Meigen). Using a combination of light microscopy and scanning electron microscopy, the morphology of the cephaloskeleton as well as the general external morphology are extensively documented, and the phylogenetic implications are discussed. Like other species of Miltogramminae, the first instar of species of Metopia possesses a strong labrum and well‐developed mouth‐hooks. Some other features found in Metopia spp. are rare in the Miltogramminae, such as a serrated ventral surface of the tip of the mouth‐hook and the lack of a posterior spiracular cavity. A few larval features apparently unique for species of Metopia have so far been documented: base of mouth‐hook with a lateral arm‐like extension and abdominal segments with transverse furrow ventrally. The body is equipped with longitudinal cuticular ridges on all segments, which may be a subfamily ground‐plan autapomorphy. Marked morphological and behavioural differences are documented between the first instar of M. argentata and that of M. argyrocephala, the adult females of which are otherwise difficult to separate.     

Length‐weight relationships of seven fish species from Jequitinhonha River basin,southeastern Brazil

The present study established the length‐weight relationships (LWR) for seven fish species from Jequitinhonha River basin, a Brazilian coastal drainage, collected with gillnets (3 to 16 cm) between 2011 and 2016. For the LWR, standard length and total weight were used. The allometric coefficient b varied from 2.66 to 3.26. These results provide biological data for a region of extreme biogeographical importance that is suffering serious environmental disturbances.     

Comparative morphology of the reproductive system of seven species of ostariophysan fishes from the upper Das Velhas River,Brazil

The success of fishes in different environments is related with the variation of reproductive strategies developed by the systematic group, which is reflected in the morphology of the reproductive system and can have ecological and evolutionary implications. This study comparatively analyzed the morphological characteristics of the male and female reproductive systems of ostariophysan fish species from the upper Das Velhas River in the São Francisco River basin, Brazil. In order to accomplish this, 393 specimens belonging to seven fish species were sampled between April 2010 and June 2015 for histological, ultrastructural, histochemical, and morphometric analyses. All the species examined have anastomosing tubular testes with unrestricted distribution of spermatogonia. Astyanax bimaculatus , A. fasciatus , A. scabripinnis , and Harttia torrenticola had their spermatozoa embedded in a glycoprotein secretion within the tubule lumen. Most species had type I spermiogenesis, whereas Rhamdia quelen had type III spermiogenesis. While all females examined had asynchronous oocyte development, there were remarkable morphological, histochemical, and morphometric differences in the ovarian follicles and enveloping layers. Hoplias malabaricus and H. torrenticola , which exhibit parental care behaviour, had a significantly larger diameter of vitellogenic oocytes and larger spermatozoa nuclei. Apareiodon ibitiensis , H. torrenticola , and A. scabripinnis , species that have rheophilic preferences, exhibited a thicker zona radiata than the other species examined. The follicular cells of R. quelen and H. torrenticola were columnar and produced a jelly coat and mucosubstances, respectively. The females of the seven fish species studied show a correlation of the reproductive strategies with the reproductive system morphology, while males retained more similar morphological characteristics between species. J. Morphol. 278:170–181, 2017. © 2016 Wiley Periodicals,Inc.     

Length‐weight relationships for 55 freshwater fish species from the Iguatemi River,Upper Paraná River basin,Brazil

This study reports the length‐weight relationship estimatives (LWRs) for 55 fish species caught in the Iguatemi River drainage, Upper Paraná River Basin, Mato Grosso do Sul State, Brazil. The LWRs of 15 of the species are provided for the first time.     

Morphometric discrimination of early life stage Lampetra tridentata and L. richardsoni (Petromyzonidae) from the Columbia River Basin

The effectiveness of morphometric and meristic characteristics for taxonomic discrimination of Lampetra tridentata and L. richardsoni (Petromyzonidae) during embryological, prolarval, and early larval stages (i.e., age class 1) were examined. Mean chorion diameter increased with time from fertilization to hatch and was significantly greater for L. tridentata than for L. richardsoni at 1, 8, and 15 days postfertilization. Lampetra tridentata larvae had significantly more trunk myomeres than L. richardsoni; however, trunk myomere numbers were highly variable within species and deviated from previously published data. Multivariate examinations of prolarval and larval L. tridentata (7.2-11.0 mm; standard length) and L. richardsoni (6.6-10.8 mm) were conducted based on standard length and truss element lengths established from eight homologous landmarks. Principal components analysis indicated allometric relationships among the morphometric characteristics examined. Changes in body shape were indicated by groupings of morphometric characteristics associated with body regions (e.g., oral hood, branchial region, trunk region, and tail region). Discriminant function analysis using morphometric characteristics was successful in classifying a large proportion (> 94.7%) of the lampreys sampled.