Lutzomyia derelicta (Diptera: Psychodidae) a singular new phlebotomine sand fly from an inselberg in northeastern amazonia

Lutzomyia derelicta n. sp. is described from specimens collected in an isolated xeric habitat in the rainforest in the north of the State of Pará, Brazil. The new species lacks the posterior bulge in the dorsal wall of the cibarium characteristic of the New World genus Lutzomyia, and the armature of the male genitalia is of the pattern found elsewhere only in the Old World species of Sergentomyia. L. derelicta is phenetically intermediate between the known species of Lutzomyia and Sergentomyia, and cannot readily be placed in any existing subgenus or species group of either genus.

The central projection of cephalic mechanosensory axons in the haematophagous bug Triatoma infestans

The projections of mechanosensory hairs located on the dorsal and lateral head of the adult haematophagous bug Triatoma infestans were analyzed by means of cobalt filling. Axons run into the anterior and posterior tegumentary nerve and project through the brain to the ventral nerve cord. The fibres are small in diameter and run as a fascicle. Some branches run into suboesophageal and prothoracic centres; others run as far as to the mesothoracic ganglion. These sensory projections resemble that of wind-sensitive head hairs of the locust. The functional role of this sensory system in this species is discussed.

Simulium (Psaroniocompsa) tergospinosum new species (Diptera: Simuliidae) in siolii group from the southern part of the State of Amazonas, Brazil

The larva, pupa, male and female of Simulium tergospinosum n. sp. are described and illustrated. The adults of this new species share many characters with species in the subgenus Psaroniocompsa, where it is placed. The larva of this species bears dorsal and lateral triangular tubercles on the abdomen and multiply branched scale-like setae on the body, suggesting that it belongs to the S. siolii species group. S. tergospinosum n.sp. was collected along the Juma River, Apuí county, in the southern part of the State of Amazonas, Brazil. The Juma, a black-water river, is a tributary of the Aripuanã River in the Madeira River hydrographic basin, on the southern part of Amazonas. Females were collected biting humans along the water courses during the sampling period (in the dry season).

Ultrastructure of spermatogenesis and sperm development in Saccocoelioides godoyi Kohn & Froes, 1986 (Digenea, Haploporidae)

Ultrastructural observations of spermatogenesis and sperm development of Saccocoelioides godoyi, an intestinal parasite of Leporinus friderici (Bloch, 1794) are described. The irregular-shaped spermatogonia form a peripheral layer, and show a prominent nucleus. Spermatocytes are larger than spermatogonia, and in the early stage present synaptonemal complex. Spermatids show nuclei smaller than the spermatocytes. Spermiogenesis is characterized by outgrowth of the zone of differentiation, presenting basal bodies, separated by an intercentriolar body. At the end of this process, the spermatozoa are released into the residual cytoplasmic mass. The spermatozoa of S. godoyi are elongate, similar to the pattern described for other Digenea, showing nuclei, mitochondria and two axonemes with the 9+1 configuration. The peripheral cortical microtubules on the dorsal and ventral faces are laterally interrupted.

Scanning and transmission electron microscopy of the tegument of Paranaella luquei Kohn, Baptista-Farias & Cohen, 2000 (Microcotylidae, Monogenea), parasite of a Brazilian catfish, Hypostomus regani

The surface topography and ultrastructure of the tegument of Paranaella luquei Kohn, Baptista-Farias & Cohen, 2000, a microcotylid monogenean parasite from the gills of Hypostomus regani (Ihering, 1905) (Loricariidae) was studied by scanning (SEM) and transmission electron microscopy (TEM). By SEM, it was observed that the tegument presents transversal ridges, forming folds in the ventral and dorsal surfaces and microvillous-like tegumental projections in the anterior and median regions of body. These projections were also observed by TEM. The tegument is made up of a syncytium delimited by apical and basal plasma membranes, containing inclusion bodies and mitochondria, connected to the nucleated region by means of cytoplasmatic processes. The tegumental cells present a well developed nucleus and cytoplasm containing inclusion bodies, similar to those found on the external layer, mitochondria, rough endoplasmatic reticulum and free ribossomes.

Morphological aspects of Schistosoma mansoni adult worms isolated from nourished and undernourished mice: a comparative analysis by confocal laser scanning microscopy

Malnutrition hampers the course of schistosomiasis mansoni infection just as normal growth of adult worms. A comparative morphometric study on adult specimens (male and female) recovered from undernourished (fed with a low protein diet - regional basic diet) and nourished (rodent commercial laboratory food, NUVILAB) white mice was performed. Tomographic images and morphometric analysis of the oral and ventral suckers, reproductive system and tegument were obtained by means of confocal laser scanning microscopy. Undernourished male specimens presented smaller morphometric values (length and width) of the reproductive system (first, third and last testicular lobes) and thickness of the tegument than controls. Besides that, it was demonstrated that the dorsal surface of the male worms bears large tubercles unevenly distributed, but kept grouped and flat. At the subtegumental region, vacuolated areas were detected. It was concluded that the inadequate nutritional status of the vertebrate host has a negative influence mainly in the reproductive system and topographical somatic development of male adult Schistosoma mansoni, inducing some alterations on the structure of the parasite.

Hepatosplenic schistosomiasis in field-based studies: a combined clinical and sonographic definition

A combined clinical and sonographic classification of hepatosplenic schistosomiasis mansoni to be used in field-based studies is proposed herein. Seven hundred forty one individuals out of 892 (83%), living in an area endemic for schistosomiasis in Brazil, have been ubmitted to clinical and ultrasound examinations. Based on two stool examinations the overall prevalence for schistosomiasis in this area was 73%. Abdominal palpation was performed with patients in dorsal decubit, during deep breath, by two experienced physicians and a portable ultrasound was used for the evaluation of liver fibrosis, portal collaterals and spleen size. Four groups of individuals were identified using data obtained by abdominal palpation and ultrasound examination: (1) palpable spleen and intense periportal thickening in 9 individuals (1.2%); (2) spleen not palpable and intense periportal thickening in 15 (2%); (3) palpable spleen with light to moderate periportal thickening in 32 (4.3%), and (4) palpable spleen with a normal liver on ultrasound in 30 (4%). The definition of hepatosplenic schistosomiasis in field-based studies as the finding of Schistosoma mansoni eggs in the stools in an individual with splenomegaly is not acceptable anymore. Abdominal ultrasound should be combined with clinical examination to accurately identify hepatosplenics in endemic areas for schistosomiasis.

Some Morphological Aspects of Cylicocyclus brevicapsulatus (Nematoda: Cyathostominae) Parasite of Horse

This paper describes some morphological aspects of Cylicocyclus brevicapsulatus (Ihle, 1920) (Nematoda: Cyathostominae) from Equus caballus in Brazil. The worms were studied using an optical microscope (measurements and illustrations) and a scanning electron microscope for a more detailed examination of the external morphology. The buccal capsule is very short, with a very thin wall, and the dorsal gutter is absent. Other morphological aspects are described including measurement of the spicules and gubernaculum.

Cercarial Chaetotaxy and Sex Differentiation of Schistosoma mansoni Deriving from Humans and Nectomys squamipes (Muridae: Sigmondontinae) in Brazil

A comparative study was made between sympatric isolates of Schistosoma mansoni: one from a wild rodent (R) Nectomys squamipes and another one from humans (H) isolated from a low endemic schistosomiasis transmission area in Brazil. Our purpose was to detect differences between them concerning chaetotaxy (number and pattern of distribution of the argentophilic papillae) of the cercariae by means of silver impregnation. No significant difference (x > 0.05) between isolates was noted. Nevertheless, a significant difference (x < 0.05) was observed in the cercarial index (ratio of the distance between the first and the second preacetabular papillae and the distance between the first and the second dorsal preacetabular papillae) of male and female cercariae in both isolates. Males presented a greater cercarial index than females. By means of multivariate analysis, male cercariae were distinguished from female cercariae through the following characteristics: average number of dorsal papillae on the right quadrant, average number of ventral middle papillae on the right quadrant (H isolate) and average number of dorsal middle papillae on the left quadrant (R isolate). The results suggest that R and H isolates belong to the same population that could complete its life cycle in rodent-snail-rodent fashion.

Anopheles albitarsis Embryogenesis: Morphological Identification of Major Events

Anopheles albitarsis embryogenesis was analyzed through confocal microscopy of clarified eggs. Using Drosophila melanogaster as reference system, the major morphogenetic events (blastoderm, gastrulation, germ band extension, germ band retraction, dorsal closure) were identified. The kinetics of early events is proportionally similar in both systems, but late movements (from germ band retraction on) progress slower in An. albitarsis. Major differences in An. albitarsis related to D. melanogaster were: (1) pole cells do not protrude from the blastoderm; (2) the mosquito embryo undergoes a 180º rotation movement, along its longitudinal axis; (3) the head remains individualized throughout embryogenesis; (4) extraembryonary membranes surround the whole embryo. A novel kind of malaria control is under development and is based on the use of genetically modified mosquitoes. Phenotypic analysis of the embryonic development of mutants will be imposed as part of the evaluation of effectiveness and risk of employment of this strategy in the field. In order to accomplish this, knowledge of the wild type embryo is a prerequisite. Morphological studies will also serve as basis for subsequent development biology approaches.

Cytotaxonomy of Simulium cauchense Floch & Abonnenc and Simulium quadrifidum Lutz (Diptera: Simuliidae) in Brazilian Amazonia

Simulium cauchense Floch & Abonnenc and Simulium quadrifidum Lutz are widely distributed in the Amazon region and are morphologically similar at the larval and pupal stages. Chromosomally, these species are readily distinguished by the position of the nucleolar organizer, which is in the short arm of chromosome I in S. cauchense and in the long arm of chromosomes III in S. quadrifidum. They also differ by three fixed inversions. Sex chromosomes are undifferentiated in both species. Chromosomal resolution of the two species allowed us to evaluate four structural features previously used as diagnostic aids at the larval stage. Characters that distinguish larvae of the two species are the number of branches and branching patterns of the dorsal abdominal setae and the dark band on each primary fan. Branching patterns of the gill histoblasts were often diagnostic, with S. quadrifidum exhibiting more proximal branching and S. cauchense more distal branching. Sites where both species occurred sometimes had larvae with one petiole branching proximally and the other distally; in these cases examination of the chromosomes permitted assignment of the specimen to species. Pigmentation patterns of larvae, on the other hand, are highly variable. Color typically is sex linked in both species.

Morphological study of the eggs and nymphs of Triatoma dimidiata (Latreille, 1811) observed by light and scanning electron microscopy (Hemiptera: Reduviidae: Triatominae)

Eggs and nymphs of Triatoma dimidiata were described using both light and scanning electron microscopy. The egg body and operculum have an exochorion formed by irregular juxtaposed polygonal cells; these cells are without sculpture and the majority of them are hexagonal in shape. The five instars of T. dimidiatacan be distinguished from each other by characteristics of the pre, meso and metanotum. The number of setiferous tubercles increases progressively among instars. The sulcus stridulatorium of 1st instar nymphs is amorphous, showing median parallel grooves; from the 2nd instar on the sulcus is, progressively, elongate, deep and posteriorly pointed with stretched parallel grooves. All instars have a trichobothrium on the apical 1/3 of segment II of the antenna. The opening of the Brindley's gland is on the mesopleura. Fifth instar nymphs have an apical ctenidium on the ventral surface of the fore tibia. Dorsal glabrous patches are found on the lateral 1/3 of abdomen. Bright oval patches are found on the ventral median line of the abdomen, from segment IV-VI; 1st instar nymphs lack these patches. Abdominal dorsal plates are present from the 1st-5th instars; the 1st instar also contains a rectangular plate in segment IX. From the 2nd instar on, variably-shaped plates are present on segments VII to IX. Morphometric data were also obtained and proved to be useful for distinguishing T. dimidiata instars.

Occurrence of hybrids and laboratory evidence of fertility among three species of the Phyllosoma complex (Hemiptera: Reduviidae) in Mexico

In seven studied communities of Western Mexico, triatomine specimens were sympatrically collected, some with atypical morphological characteristics in contrast to pure specimens, which were presumed to be hybrids. More than 200 specimens of Meccus pallidipennis and Meccus longipennis with brown-yellow markings on dorsal connexival segments were collected in Ahuacapán and Quitupan. In La Mesa, more than 60 specimens similar to Meccus picturatus in most morphological characteristics (including size) were collected, although they presented a largely yellowish corium like M. pallidipennis. Interfertility was proven between all of the studied wild hybrid specimens, as well as between all the experimental laboratory hybrids. Two different phenotypes (M. picturatus and M. longipennis) were obtained from crosses between M. picturatus x M. picturatus and M. longipennis x M. longipennis from the three studied localities in state of Nayarit as from La Mesita. Results support the hypothesis that the subspecific ranking of those triatomines may, therefore, be more appropriate because reproductive isolation has not been developed and complete interbreeding was recorded.

Characterization of the external female genitalia of six species of Triatominae (Hemiptera: Reduviidade) by scanning electron microscopy

By macroscopic and microscopic dorsal side observation, it was noted that the IX and X segments of two species each of Panstrongylus and Triatoma terminate in an elongated way, whereas they terminate abruptly in the two species of Rhodnius. Scanning observation of the dorsal, ventral, lateral and posterior sides of the female genitalia of Panstrongylus herreri, Panstrongylus megistus, Rhodnius colombiensis, Rhodnius prolixus, Triatoma infestans and Triatoma vitticeps revealed that these six species are generally and specifically distinguished based on these elements. We describe several components that distinguish P. herreri from P. megistus: four on the dorsal side: the VII, VIII, IX and X segments, on the ventral view, three: VII sternite, VIII gonocoxite and VIII gonapophyse, on the lateral view one character, VIII gonocoxite and on the posterior view three characters: VIII and IX gonocoxite and XI gonopophyse. Comparing R. colombiensis and R. prolixus, there were three distinct characters on the dorsal side: the VII, VIII and X segments, on the ventral view three characters: the IX and X segments and VIII gonocoxite and on the posterior view four characters: the VIII, IX, X segments and VIII gonapophyse that distinguish the two species. T. infestans and T. vitticeps have four different characters on the dorsal side: the VII, VIII, IX and X segments, on the ventral view four characters: the VII and X segments, VIII gonocoxite and VIII gonapophyse, on the lateral view two characters, IX and X segments and on the posterior view four characters: the IX and X segments, VIII gonocoxite and VIII gonapophyse that distinguish the two species. Examination of the external female genitalia of six triatomine species by scanning suggests that these components are useful for taxonomical studies.

Lanfrediella amphicirrus gen. nov. sp. nov. Nematotaeniidae (Cestoda: Cyclophyllidea), a tapeworm parasite of Rhinella marina (Linnaeus, 1758) (Amphibia: Bufonidae)

The family Nematotaeniidae, tapeworms commonly found in the small intestines of amphibians and reptiles, includes 27 recognised species distributed among four genera: Bitegmen Jones, Cylindrotaenia Jewell, Distoichometra Dickey and Nematotaenia Lühe. The taxonomy of these cestodes is poorly defined, due in part to the difficulties of observing many anatomical traits. This study presents and describes a new genus and species of nematotaeniid parasite found in cane toads (Rhinella marina) from eastern Brazilian Amazonia. The cestodes were collected during the necropsy of 20 hosts captured in the urban area of Belém, Pará. The specimens were fixed and processed for light microscopy, scanning electron microscopy (SEM) and three-dimensional (3D) reconstruction. Samples were also collected for molecular analyses. The specimens presented a cylindrical body, two testes and paruterine organs. However, they could not be allocated to any of the four existing nematotaeniid genera due to the presence of two each of dorsal compact medullary testes, cirri, cirrus pouches, genital pores, ovaries and vitelline glands per mature segment. Lanfrediella amphicirrus gen. nov. sp. nov. is the first nematotaeniid studied using Historesin analysis, SEM and 3D reconstruction, and it is the second taxon for which molecular data have been deposited in GenBank.