Wyeomyia staminifera, a new species of mosquito from Brazil (Diptera: Culicidae)

Wyeomia staminifera n. sp. is described from specimens collected into the forest of the Amazon and Southeast Regions of Brazil. The description includes illustrations of female and male genitalias and chaetotaxy of pupa and larva. Wy. staminifera is closely related to Wy. aporonoma, but they are distinguishable in all stages.

A new species of Cullex (Melanoconion) from the Amazonian Region (Diptera: Culicidae)

Culex (Melanoconion) eknomios, a new species from Amazonian region is described, including the adult, pupal and larval stages. Available data about distribution and binomics are presented.

Scanning electron microscopy of the eggs of two species of Anopheles (Kerteszia) (Diptera: Culicidae)

The eggs of Anopheles cruzii and An. bellator are described and illustrated using scanning electron micrographs. Hatching was observed, and larval exit documented. No morphological differences were found between the eggs of the two species.

Crithidia ricardoi sp. n. a new species of trypanosomatidae isolated from Culex saltanensis Dyar, 1928 (Diptera: Culicidae)

A flagellte trypanosomatid was isolated in culture from the digestive tract of the mosquito Culex saltanensis Dyar, 1928. It grows exuberantly in liver infusion in the form of epimastigotes and choanomastigotes typical of the genus Crithidia. The trypanosomatid was compared to C. deanei, C. fasciculata, C. luciliae, C. oncopelti and C. guilhermei. The techniques used for comparison were electron transmission microscopy, isoenzymes and kDNA restriction profiles. No endosymbionts were found at electron microscopy. Results for the biochemical methods employd indicate that the trypanosomatid isolated from C. saltanensis is a new species of Crithidia. The name C. ricardoi sp. n. is proposed for thes new species.

Immature stages of mosquitoes (Diptera: Culicidae) Collected during the autumn-winter period in Cordoba Province, Argentina

Eggs, immature mosquito collections were made at Cosquin, La Calera ( Chaco phytogeographic region), Villa Allende and Villa del Rosario (Espinal phytogeographic region) during April/September of two consecutive years 1989, 1990. Specific immature habitats in each locality were identified and sampled monthly. Eggs and/or immatures of Aedes albifasciatus, Ae. fluviatilis, Anopheles albitarsis, culex acharistus, Cx. apicinus, Cx. bidens, Cx. coronator, Cx. chidesteri, Cx. dolosus, Cx. maxi, Cx. quinquefasciatus, Cx. saltanensis, Psorophora ciliata and Uranotaenia lowii were collected. Three species (Cx. acharistus, Cx. dolosus and Cx. quinquefasciatus) were collected during the sampling period for all developmental stages. This suggests that immature of these species do not overwinter but continue to develop throughout the cold autumn and winter seasons.

Wyeomyia luteoventralis Theobald, the type species of the subgenus Dendromyia Theobald (Diptera: Culicidae)

Wyeomyia (Dendromyia) luteoventralis is redescribed from females, males, larvae and pupae collected at the type locality, in Brazil, and compared to the closely related species. At least six species - Wy. luteoventralis, Wy. ypsipola, Wy. testei, Wy. trifurcata, Wy. complosa and Wy. jocosa - appparently, belong to a monophyletic group, the subgenus Dendromyia. All other species previously included in Dendromyia are hereby excluded from this subgenus and retained in genus Wyeomyia without subgeneric placement.

The biology of Aedes (Ochlerotatus) albifasciatus Macquart, 1838 (Diptera: Culicidae) in Central Argentina

Aedes albifasciatus is a flood water mosquito ocurring in the southern countries of South America. It is a competent vector of the Western Equine Encephalitis (WEE) and causes important losses on milk and beef production in central Argentina. Field work was carried out from December 1990 to March 1993, on a monthly basis during the dry season and biweekly during the rainy season. Larvae were collected using the 'dipping' technique and females with CDC traps baited with CO2. Field collected larvae were used to build laboratory cohorts, from which basic population parameters were estimated. Eggs survived up to six months on dry soil, although there was a linear decrease of viability with time. At 23ºC, larval development time was around nine days, and all adults emerged within one week. The estimation of larval development in the laboratory seems to be very near the development on the field, as larvae have been collected on average eight days after a rainfall. Egg to adult survival was 83%, with the highest mortality on fourth larval instar (6%). In the laboratory studies, sex proportion among the adults was 1:1, females lived longer than males (median 13 and five days, respectively), and adult survival pattern showed a constant number of individuals dying per unit time. Field collected females layed an average of 84 eggs per batch, and completing up to five gonotrophic cycles, suggesting an estimated survival of up to 35-50 days.

Distribution and hybridization between Culex pipiens and Culex quinquefasciatus (Diptera: Culicidae) in Argentina

To better undesrtand the distribution of Culex pipiens and Cx. quinquefasciatus in Argentina, samples were collected from six localities situated in a North-South line from Castelli (Chaco Province) to Puerto Madryn (Chubut Province). Identification was based on the morphology of male genitalia. Only Cx. quinquefasciatus was found in Castelli and Esperanza, while in Rosario, 95.3% belonged to this species and 4.7% represented hybrid forms. Southern samples included only Cx. pipiens. With the purpose of verfying if Cx. pipiens and Cx. quinquefasciatus hybridize, different crosses between the two species were perfomed. All crosses produced viable egg rafts. Hatching ranged from 70 to 100%, except in one cross, female Cx. pipiens x male Cx. quinquefasciatus, where a high incompatibility was observed (11.1%hatch). The F1 hybrids obtained all crosses were fertile. The finding of hybrid forms in nature can be interpreted as evidence for subspecific status of Cx. pipiens and Cx. quinquefasciatus in Argentina.

Initiation of primary cell cultures from embryos of the mosquitoes Anopheles albimanus and Aedes taeniorhynchus (Diptera: Culicidae)

Primary cell cultures were obtained from eggs of Anopheles albimanus and Aedes taeniorhynchus mosquitoes, vectors of human malaria and of Venezuelan equine encephalitis virus, respectively. The cellular growth of the An. albimanus cells began four weeks after explanting the embryonic tissues in MK/VP12 medium, supplemented with 15% fetal bovine serum. The culture showed heterogeneous cellular morphology. With regard to the Ae. taeniorhynchus culture, growth occurred three weeks after initiating the culture in MM/VP12 medium. The majority of cells were small and round. Karyotypes were examined in the latter species.

The identification of Anopheles (Nyssorhynchus) rondoni (Diptera: Culicidae) in Mato Grosso, Brazil: an analysis of key character variability

A morphological study was made of a population of Anopheles (Nyssorhynchus) rondoni (Neiva and Pinto) from northern Mato Grosso, Brazil. This population usually lacked the primary key character of a dark basal band on hindtarsomere 3, i.e., hindtarsomere 3 was all white as in most other members of the subgenus. It was determined that this species can be recognized instead by the presence of a dark spot on the thorax made up of a large dark prescutellar space that is contiguous with a concolorous central area on the scutellum. A secondary character of a dark area on the costa created by the fusion of the humeral dark, presector dark and sector dark proximal spots is also usually reliable. Regression analyses comparing the lengths and ratios of the dark bands on hindtarsomeres 2 to those on 3 describe a straight line relationship. This suggests that the "atypical" population is at one end of a character gradient. We propose that in the subgenus Nyssorhynchus individuals that have a long basal band on hindtarsomere 2 are more likely to also have a basal band on hindtarsomere 3. The pupal stage of this species has not been previously described. Reared-associated specimens from this study show that the pupa can be easily differentiated from all other Nyssorhynchus by the relatively stout, usually 2 or 3 branched (1-5), setae 1 and 5 on segments IV-VII.

Two new species of the subgenus Peytonulus of Sabethes (Diptera: Culicidae) from Colombia

The adults and male genitalia of two new species of Sabethes subgenus Peytonulus are described from Colombia. The male genitalia are illustrated and the species are distinguished from one another and other members of the subgenus.

Identification of species related to Anopheles (Nyssorhynchus) albitarsis by random amplified polymorphic DNA-Polymerase chain reaction (Diptera: Culicidae)

Species-specific Random Amplified Polymorphic DNA-Polymerase chain Reaction (RAPD-PCR) markers were used to identify four species related to Anopheles (Nyssorhynchus) albitarsis Lynch-Arribàlzaga from 12 sites in Brazil and 4 in Venezuela. In a previous study (Wilkerson et al. 1995), which included sites in Paraguay and Argentina, these four species were designated "A", "B", "C" and "D". It was hypothesized that species A is An. (Nys.) albitarsis, species B is undescribed, species C is An. (Nys) marajoara Galvão and Damasceno and species D is An. (Nys.) deaneorum Rosa-Freitas. Species D, previously characterized by RAPD-PCR from a small sample from northern Argentina and southern Brazil, is reported here from the type locality of An. (Nys.) deaneorum, Guajará-Mirim, state of Rondônia, Brazil. Species C and D were found by RAPD-PCR to be sympatric at Costa Marques, state of Rondônia, Brazil. Species A and C have yet to be encountered at the same locality. The RAPD markers for species C were found to be conserved over 4,620 km; from Iguape, state of São Paulo, Brazil to rio Socuavo, state of Zulia, Venezuela. RAPD-PCR was determined to be an effective means for the identification of unknown species within this species complex.

Classification of immature stage habitats of Culicidae (Diptera) collected in Córdoba, Argentina

In order to classify mosquito immature stage habitats, samples were taken in 42 localities of Córdoba Province, Argentina, representing the phytogeographic regions of Chaco, Espinal and Pampa. Immature stage habitats were described and classified according to the following criteria: natural or artificial; size; location related to light and neighboring houses; vegetation; water: permanence, movement, turbidity and pH. Four groups of species were associated based on the habitat similarity by means of cluster analysis: Aedes albifasciatus, Culex saltanensis, Cx. mollis, Cx. brethesi, Psorophora ciliata, Anopheles albitarsis, and Uranotaenia lowii (Group A); Cx. acharistus, Cx. quinquefasciatus, Cx. bidens, Cx. dolosus, Cx. maxi and Cx. apicinus (Group B); Cx. coronator, Cx. chidesteri, Mansonia titillans and Ps. ferox (Group C); Ae. fluviatilis and Ae. milleri (Group D). The principal component analysis (ordination method) pointed out that the different types of habitats, their nature (natural or artificial), plant species, water movement and depth are the main characters explaining the observed variation among the mosquito species. The distribution of mosquito species by phytogeographic region did not affect the species groups, since species belonging to different groups were collected in the same region.