Density-dependent morphological plasticity and trade-offs among vegetative traits in Eichhornia crassipes (Pontederiaceae)

Density-dependent responses are an important component of the organism life-history, and the resource allocation theory is a central concept to the life-history theory. When resource allocation varies due to environmental changes, a plant may change its morphology or physiology to cope with the new conditions, a process known as phenotypic plasticity. Our study aimed to evaluate how plant density affects Eichhornia crassipes allocation patterns. A total of 214 individuals in high and low density were collected. The density effect was observed in all plant traits examined including biomass accumulation. All traits of E. crassipes demonstrated higher values in high density conditions, except for biomass of leaves. Density exhibited a high influence on vegetative traits of E. crassipes, but did not influence allocation pattern, since a trade-off among the vegetative traits was not found. The morphological plasticity and the absence of trade-offs were discussed as strategies to overcome neighbor plants in competition situations. In high density conditions, there were clear changes in the morphology of the plants which probably allows for their survival in a highly competitive environment.

Comparative leaf morphological analysis of 20 species of Chrysobalanaceae

Morphological studies focusing on vegetative traits are useful in identifying species when fertile material is not available. The aim of this study was to assess the application of comparative leaf morphology to identify species of the Chrysobalanaceae family. The morphological observations were made with a stereomicroscope. We used the diaphanization technique for viewing venation details. It is shown the descriptions of the leaf morphology, illustrations and an identification key for 20 species from genera Couepia, Licania and Parinari (Chrysobalanaceae) occurring in the Adolpho Ducke Forest Reserve, Manaus, AM, Brazil. The key was constructed using the DELTA (DEscription Language for TAxonomy) software. Leaf traits such as the presence of intersecondary venation and the type of insertion of secondary veins were recorded for each species. These morphological leaf traits are reliable for identifying species of Chrysobalanaceae

On the morphological "variation" on the aedaegus of Schizotetranychus oryzae (acari, prostigmata, tetranychidae)

Sobre a "variação" morfológica do edéago de Schizotetranychus oryzae (Acari, Prostigmata, Tetranychidae). Apresenta-se uma nota sobre a ocorrência do ácaro do arroz, Schizotetranychus oryzac Rossi de Simons, No Brasil, com observações sobre a "variação" morfológica do edéago do macho desta espécie de ácaro.

New histochemical and morphological findings in the female genital tract of Boophilus microplus (Acari, Ixodidae): an attempt toward the elucidation of fertilization in ticks

At present not only is the site of fertilization in ticks still unknown but it is also unclear as to how this mystery can be solved. Signs of fertilization can be observed throughout the female genital tract and these can be clues for the elucidation of the unsolved questions relating to ticks fertilization. In Boophilus microplus (Canestrini, 1887) the most important signs are the following: the final eversion of the acrosomal canal in females ready for oviposition; the presence of small tubules, resembling the subplasmalemal process of the spermatozoon between the oviduct cells; budding nuclei throughout the female genital tract; and the two Feulgen and DAPI positive areas in the oocyte at vitelogenesis. These morphological characteristics suggest that fertilization takes place in the internal cylinder which extends from the uterus to the ovary itself.

Relative growth and morphological sexual maturity of Chasmagnathus granulatus (Crustacea, Varunidae) from a mangrove area in southeastern Brazilian coast

The relative growth and morphological sexual maturity of Chasmagnathus granulatus Dana, 1851 are presented for the first time to a mangrove population. The crabs were obtained during low tide periods, in the mangrove of Jabaquara Beach, Paraty, Rio de Janeiro, Brazil. All crabs in intermolt stage were sexed and had their body parts measured as follows: body height (BH), carapace length (CL) and width (CW), major cheliped propodus height (PH) and length (PL) for each sex, gonopod length (GL) and abdomen width (AW) for males and females, respectively. The relative growth was described using the allometric equation y=ax b and the size at onset sexual maturity was achieved using the software Mature I. The size of specimens ranged from 4.1 mm to 39.5 mm CW. The growth pattern was different between sexes in the cheliped relationships; the relationships BH vs. CW evidenced positive allometry for juveniles; PL vs. CW and PH vs. CW positive allometry for most crabs except juvenile females; AW vs. CW and GL vs. CW evidenced positive allometry for juveniles and isometry for adults. The relationships that best indicated the change from the juvenile to the adult phase were PH vs. CW for males and AW vs. CW for females. The size in which 50% of males from this population are mature is at 19.7 mm of CW (F=144.14; p<0.05) and for females it is at 19.2 mm of CW (F=166.54; p<0.05). The sizes obtained in this mangrove population are larger than those from previous studies, that could be attributed to a species plasticity concerning the habitat structure.

Geographic distribution and morphological variation in Mimon bennettii (Chiroptera, Phyllostomidae)

We studied discrete and quantitative data from 88 specimens of the subgenus Mimon previously identified as Mimon bennettii (Gray, 1838) and M. cozumelae Goldman, 1914 from diverse parts of their range. Our data indicate that specimens of Mimon bennetii in Brazil presented geographic variation in morphometrical characters and mosaic variation in qualitative traits. Specimens from the Cerrado biome collected in Brazilian states like Piaui, Tocantins, and Goiás have longer forearms than those distributed in the Atlantic and Amazon forested domains. Based on morphometrics, as showed by t-tests, specimens of M. bennettii from the Brazilian Cerrado resemble phenetically more with M. cozumelae than the M. bennettii from Atlantic Forest. Characters presently used to diagnosis M. cozumelae also were also recorded to M. bennettii in diverse parts of Brazil, making that validity of M. cozumelae questionable based on this kind of traits. This research also updated the geographic distribution to the M. bennettii in Brazil.

Morphological aspects of cell reabsorption in laying queens and workers of Apis mellifera (Hymenoptera, Apidae)

The occurrence of cell reabsorption in the ovaries of queens in several rates of laying eggs, artificially impeded of laying, and in nurse workers, of Apis mellifera (Linnaeus, 1758), was studied with light (LM) and transmission electron microscopy (TEM). Two types of structures were described and named by analogy with vertebrates ovarian structures, as corpus luteus, when resulting from the reabsorption of the follicular cells after ovulation, and corpus atresicus when resulting from total follicular reabsorption at any oocyte developmental stage. These structures have the same morphological characteristics and physiological signification in both castes. The corpus luteus occurrence indicates ovulation and its number is correspondent to the queen's rates of oviposition. The presence of this structure in nurse workers ovarioles shows that this caste may lay eggs. The incidence of corpus atresicus in queens decay with the increasing of the oviposition indicating that the inhibition of the normal sequence of oocyte maturation in the ovaries is deleterious. Both, corpus luteus and corpus atresicus incidence may be influenced by environmental factors.

Sex ratio and morphological characteristics of rufous gnateaters, Conopophaga lineata (Aves, Passeriformes) in Atlantic forest fragments

Unequal sex ratios lead to the loss of genetic variability, decreasing the viability of populations in the long term. Anthropogenic activities often disturb the natural habitats and can cause alterations in sex ratio and morphological characteristics of several species. Forest fragmentation is a major conservation concern, so that understanding its effects in natural populations is essential. In this study, we evaluated the sex ratio and the morphological characteristics of Rufous Gnateaters (Conopophaga lineata (Wied, 1831)) in small and large forest fragments in Minas Gerais, Brazil. Birds (n = 89) were sexed by plumage characteristics and molecular markers. The molecular analysis showed that plumage is not a totally reliable method for sexing Rufous Gnateaters. We observed that sex ratio did not differ between large and small forest fragments, but birds in small fragments had larger wings and tarsus. Wing and tarsus changes may affect the movement ability of individuals within and among forest fragments. In conclusion, Rufous Gnateaters have been able to survive in both small and large Atlantic rain forest fragments without altering their sex ratio, but morphological changes can be prejudicial to their long term survival.

Morphological and functional study of the marginal sphincter of the sea anemones Phymactis clematis and Aulactinia marplatensis from intertidal of Mar del Plata, Argentina

It was made the characterization of marginal sphincter to the species Phymactis clematis (Drayton in Dana, 1849) and Aulactinia marplatensis (Zamponi, 1977), from intertidal ecosystem through their morphogical and functional study. The species P. clematis has a circumscript sphincter of palmate type. This muscle is constituted by a mesogloeal axis and several mesogloeal subaxes. Axis as well as subaxes give a support to the endoderm which border is smooth. Aulactinia marplatensis has a circunscript sphincter pinnate type. The axis has a truncated cone shape while in P. clematis the shape is cylindrical on its origin and it is bifurcated at the end. Both species experiments were carried out using the isolated muscles. They were stimulated at increasing KCl concentrations ranging from 20 to 200 mM. The results were analysed in the form of dose-response curves expressed in tension in grams force vs concentration. Contractil force increases in a sigmoid form to increasing KCl concentrations. The correlation between morphology and function and the differences shown in both species would be related to their intertidal distribution.

Morphological characterization and sex-related differences of the mandible of the armadillos Chaetophractus vellerosus and Zaedyus pichiy (Xenarthra, Dasypodidae), with consideration of dietary aspects

The morphological characteristics of the mandible of adult Chaetophractus vellerosus (Gray, 1865) and Zaedyus pichiy (Desmarest, 1804) were studied to establish its generalized design and to identify inter- and intra- (sexual) specific differences. Morphological descriptions were complemented with the application of univariate and multivariate (analysis of correlation matrices, PCA, discriminant analysis) techniques. The mandible of both species is very similar, and is characterized by elevated condyle, well developed angular process, distinct coronoid process, tooth row which extends to the rear end of the angle between body and ramus, and unfused but firm symphysis. Although both armadillos are omnivorous, a more slender configuration of the jaw in Z. pichiy could be indicative of a better adaptation of its masticatory apparatus to insectivory. The PCA showed an almost total segregation of both species on PC1 (47.7% of the total variance), with C. vellerosus being associated to mandibles taller and with wider body and ramus. Zaedyus pichiy was characterized by heavy loadings of length parameters on PC2 (22.6% of the variance). A small degree of sexual dimorphism was found, with size-based differences in C. vellerosus (larger mandibles in females) and shape-based differences in Z. pichiy (taller mandibles in males, longer ones in females). Correlations between variables were higher in males of both species, indicating a more stable shape of the mandible than in females. The selected parameters to discriminate sexes were the body length of the mandible in C. vellerosus (correct classification: ca. 86% in males, 81% in females), and the height of the mandible at the level of the last tooth in Z. pichiy (near 85% of right assignment in both sexes). The inclusion of a new variable (body length) in the latter species improved the classification of the females to 100%. Teeth are typically 10 in C. vellerosus and 9 in Z. pichiy, but aberrancies in this basic number, such as unilateral or bilateral extra or fewer teeth, are common.

Novelties from a cave lace bug (Heteroptera, Tingidae): first nymphal description with a discussion on the morphological patterns of Vianaidinae immatures

A nymph of Thaumamannia Drake & Davis, 1960, a rare vianaidine genus known only from adults, is described by the first time. The specimens were collected in the soil and walls of caves located in the state of Pará, Brazil. This is the first record of Vianaidinae for Brazil. The T. vanderdrifti fifth instar is compared with the same stadium of Anommatocoris coleopteratus (Kormilev, 1955), the only other vianaidine nymph described so far, and patterns between them and within the family are also discussed.

Morphological development of Corydoras aff. paleatus (Siluriformes, Callichthyidae) and correlation with the emergence of motor and social behaviors

Here we examine major anatomical characteristics of Corydoras aff. paleatus (Jenyns, 1842) post-hatching development, in parallel with its neurobehavioral evolution. Eleutheroembryonic phase, 4.3-8.8 days post-fertilization (dpf); 4.3-6.4 mm standard length (SL) encompasses from hatching to transition to exogenous feeding. Protopterygiolarval phase (8.9-10.9 dpf; 6.5-6.7 mm SL) goes from feeding transition to the commencement of unpaired fin differentiation, which marks the start of pterygiolarval phase (11-33 dpf; 6.8-10.7 mm SL) defined by appearance of lepidotrichia in the dorsal part of the median finfold. This phase ends with the full detachment and differentiation of unpaired fins, events signaling the commencement of the juvenile period (34-60 dpf; 10.8-18.0 mm SL). Eleutheroembryonic phase focuses on hiding and differentiation of mechanosensory, chemosensory and central neural systems, crucial for supplying the larval period with efficient escape and nutrient detection-capture neurocircuits. Protopterygiolarval priorities include visual development and respiratory, digestive and hydrodynamic efficiencies. Pterygiolarval priorities change towards higher swimming efficacy, including carangiform and vertical swimming, necessary for the high social interaction typical of this species. At the end of the protopterygiolarval phase, simple resting and foraging aggregations are seen. Resting and foraging shoals grow in complexity and participant number during pterygiolarval phase, but particularly during juvenile period.

The distribution of two morphological forms of Lutzomyia longipalpis (Lutz & Neiva) (Diptera: Psychodidae)

The males of the sandfly Lutzomyia longipalpis occur in two forms, one which bears a single pair of pale spots on tergite 4 and another in which an additional pair of spots characterizes tergite 3. Almost complete reproductive isolation between sumpatric populations of the two forms and between allopatric populations of the one-spot form has been reported (Ward et al., 1983). Micromorphological differences in cuticular structures on the spots have also been observed and may be sites of pheromone release (Lane & Ward, 1984). Detais of the known distribution of the two are based on the examination of new specimens captured in Brazil during 1982, as well as museum collections and specimens from other laboratories. Males with a single pair of pale spots have been found from Mexico to southern Brazil, whilst the two-spot form is found only from the state of Maranhão in North Brazil to Minas Gerais and the border with Paraguay. In the eastern area of Brazil the two forms occur sympatrically in some locations and separately in others.

New morphological data on Opecoeloides pedicathedrae Travassos, Freitas & Buhrnheim, 1966 (Digenea: Opecoelidae)

New morphological data on the ventral sucker of Opecoeloides pedicathedrae with ten papilliform processes, original figures and measurementes, are reported.

Morphological evidence by scanning electron microscopy of excretion of metacyclic forms of Trypanosoma cruzi in vector's urine

Comparision by scanning electron microscopy (SEM) of Trypanosoma cruzi flagellates attached to the cuticle of the rectal gland of infected Dipetalogaster maxima nymphs, showed marked differences before amd after feeding. Before feeding numerous metacyclic trypomastigotes were observed among the abundant epimastigotes that formed the carpet of flagellates. On the other hand, in insects that were allowed to urinate for 24 hours after a meal, the metacyclics were scarce,indicating that they had been detached by the urine flow. An asymetric type of cell division, probably originating both an epi-and a trypomastigote, was occasionally observed. The occurrence of swellings at different levels of the flagella of epimastigotes suggests that secondary sites of attachment may be common.