RESUMO Dichelacera matogrossensis sp. nov. é descrita baseada em fêmeas da Chapada dos Guimarães, estado do Mato Grosso, Brasil. São fornecidas diagnose, discussão e ilustrações.

ABSTRACT Dichelacera matogrossensis sp. nov. is described based on females from the Chapada dos Guimarães, state of Mato Grosso, Brazil. Diagnosis, discussion and illustrations are provided.

É descrita uma nova espécie de Tabanidae (Diptera), Chlorotabanus flagellatus sp. nov. , distribuída na região amazônica, Estados do Amazonas e Pará. Diagnose, discussão e ilustrações dos caracteres externos e internos são fornecidas.

We described a new species of Tabanidae (Diptera), Chlorotabanus flagellatus sp. nov., distributed in the Amazon region, in the States of Amazonas and Pará. Diagnosis, discussion and illustrations of external and internal characters are provided.

Dichelacera (Dichelacera) gemmae sp.n. é descrita baseada em 28 fêmeas coletadas em vegetação de cerrado, no município de Carolina, Sul do Maranhão.

Dichelacera (Dichelacera) gemmae sp.n. is described based on 28 females collected in open vegetation of "cerrado", in Carolina municipality, South of Maranhão state, Brazil.

É apresentada uma chave dicotômica para os três subgêneros e onze espécies do gênero Philipotabanus Fairchild com registros na Amazônia. É descrita pela primeira vez Philipotabanus (P.) obidensis sp. nov., do estado do Pará. Diagnoses, figuras e distribuição das espécies são fornecidas.

A key to eleven species and the three subgenera of Amazonian Philipotabanus Fairchild is presented. Philipotabanus (P.) obidensis sp. nov., from Pará State, is described for the first time. Diagnosis, figures and distribution are presented for all species.

Tabanid females are better known as hematophagous on man and other mammals, and linked to mechanical transmission of parasites. The association between tabanids and reptiles is poorly known, but has been gaining more corroboration through experiments and occasional observation in the tropics. The present study was conducted at a military base (CIGS/BI-2), situated 54 km from Manaus, Amazonas, in a small stream in a clearing (02°45'33"S; 59°51'03"W). Observations were made monthly, from April 1997 to March 1998, during two consecutive days. At the same time, other vertebrate animals were offered, including humans. However in this paper only data obtained on a common caiman, Caiman crocodilus (Linn.), and an anaconda, Eunectes murinus (Linn.), in diurnal observations from 05:30 a.m. to 18:30 p.m., will be discussed. A total of 254 tabanid specimens were collected, 40 from the anaconda and 214 from the caiman. Four tabanid species were recorded on these two reptiles: Stenotabanus cretatus Fairchild, S. bequaerti Rafael et al., Phaeotabanus nigriflavus (Kröber) and Tabanus occidentalis Linn. Diurnal activities showed species-specific patterns. The first three species occurred only in the dry season. T. occidentalis occurred during the whole observation period, and with increased frequency at the end of the dry season. We observed preferences for body area and related behavior of the host. Observations on the attack of tabanids on one dead caiman are also presented.