Muitos carrapatos argasídeos são conhecidos somente por descrições larvais, nas quais a quetotaxia associada a outros caracteres morfológicos tem sido usada para separar gêneros e espécies. No entanto, as ilustrações sobre esses caracteres são baseadas somente em microscopia óptica e muitos deles não estão claramente definidos. Devido às dificuldades em determinar estágios larvais e ninfais de alguns gêneros, elaboramos chaves ilustradas para os estágios imaturos de argasídeos, incluindo uma lista atualizada de espécies conhecidas da região Neotropical. Incluímos também uma chave ilustrada para larvas das espécies de Ornithodoros do Brasil baseada em microscopia eletrônica de varredura.

Many argasid tick species are known only through their larval descriptions, in which the chaetotaxy, together with other external morphological characteristics, has been used to separate genera and species. However, the illustrations of these features are based on optical microscopy alone and many of these features are not clearly defined. Because of the difficulties in determining the larval and nymph stages of some genera, we have prepared illustrated keys for the immature stages of argasids, including an up-to-date list of the known species of the Neotropical region. We have also included an illustrated key for larvae of the Ornithodoros species from Brazil, based on scanning electron microscopy.

Ixodes schulzei Aragão & Fonseca é um carrapato endêmico do Brasil e já foi relatado nas regiões Norte (estado de Rondônia), Sudeste (estados de Minas Gerais, Rio de Janeiro e São Paulo) e Sul (estado de Santa Catarina), tendo sido encontrado sempre em associação com o rato d'água Nectomys squamipes (Brandt). Esta comunicação registra a primeira ocorrência dessa espécie de carrapato no estado do Paraná, região Sul do Brasil e constitui o primeiro relato de Akodon montensis(Thomas) e Oryzomys russatus (Wagner) como hospedeiros.

Ixodes schulzei Aragão & Fonseca is an endemic tick to Brazil and has already been reported in the northern (State of Rondonia), southeastern (States of Minas Gerais, Rio de Janeiro and Sao Paulo) and southern (State of Santa Catarina) regions, always found in association with the water rat Nectomys squamipes(Brandt). This communication records the first occurrence of this tick species in the State of Parana, southern region of Brazil, and it constitutes its first report on Akodon montensis (Thomas) andOryzomys russatus (Wagner) hosts.

O objetivo deste trabalho foi registrar novos hospedeiros paraIxodes luciae Sénevet no estado do Pará, Brasil, e um caso de malformação em uma ninfa dessa espécie de carrapato. Os novos hospedeiros são Marmosa murina(parasitado por fêmeas) e Philander opossum(parasitado por ninfas). Uma dessas ninfas apresentou uma malformação na parte posterior do opistossoma em forma de coração.

The aim of this paper is to record new hosts for Ixodes luciae Sénevet in the State of Para, Brazil, and present a case of malformation (teratogeny) in a nymph of this species. The new host records are Marmosa murina (parasitized by females) and Philander opossum (parasitized by nymphs). One of these nymphs showed malformation in the posterior margin of the opisthosoma resulting in a heart shaped posterior end.

Amblyomma varium, commonly known in Brazil as the "carrapato-gigante-da-preguiça" (sloth's giant tick) is found from southern Central America to Argentina. The present study adds information on the geographical distribution of A. varium, as well as on their hosts, based on material deposited in the main Brazilian collections and on the available literature. Eighty-two vials, containing 191 adult specimens, deposited in five Acari collections between 1930 and 2001, were examined. These vials included data on the host and collection localities. The biology of A. varium is unknown. However it is known that, during the adult stage, the tick presents a high host specificity and is found almost exclusively on the sloths Bradypus tridactylus, B. variegatus, B.torquatus (Bradypodidae), Choloepus hoffmanni and C. didactylus (Megalonychidae). Based on the material examined, the states of Rondônia, Amazonas, Bahia and Alagoas are newly assigned to geographic distribution of A. varium in Brazil.

Oviposition and eclosion periods for Ixodes didelphidis were observed under two temperatures (25ºC and 27ºC) and 90-95% humidity. Although there was a significant increase in the eclosion period (p<0.05) and a tendency to increase the oviposition period at 25ºC, there was neither significant differences in the interval (days), until maximum peak of eclosion nor in the number of emerging larvae during the peak nor the total number of emerged larvae. These temperature values are not critical for embryological development of the species. Because at 27ºC and under high humidity the oviposition and eclosion periods are shorter, and the percentage of emerged larvae is higher, we consider this to be the ideal temperature for laboratory studies.