Distribution and ecology of dictyostelids in Madagascar

Samples for isolation of dictyostelid cellular slime molds were obtained from 20 collecting sites at 18 localities in south central and southeastern Madagascar during May 2009. At least thirty species of dictyostelids representing seven genera were recovered from 52 samples of soil/humus. This total included 17 species described as new to science, 13 species already known from various localities throughout the world, and four isolates that remain unidentified. Fourteen of the new species isolated from these samples are members of the whorl-branched, light-spored genus Heterostelium (formerly Polysphondylium). The overall level of species richness of dictyostelids in Madagascar is greater than what is known for all of mainland Africa sampled to date. Levels of biodiversity in Madagascar were higher for mesic than for xeric vegetation types, and each of the newly described species of Heterostelium appeared to have a limited distribution among the localities sampled.

Crustal variability along the rifted/sheared East African margin: a review

The East African margin between the Somali Basin in the north and the Natal Basin in the south formed as a result of the Jurassic/Cretaceous dispersal of Gondwana. While the initial movements between East and West Gondwana left (oblique) rifted margins behind, the subsequent southward drift of East Gondwana from 157 Ma onwards created a major shear zone, the Davie Fracture Zone (DFZ), along East Africa. To document the structural variability of the DFZ, several deep seismic lines were acquired off northern Mozambique. The profiles clearly indicate the structural changes along the shear zone from an elevated continental block in the south (14°–20°S) to non-elevated basement covered by up to 6-km-thick sediments in the north (9°–13°S). Here, we compile the geological/geophysical knowledge of five profiles along East Africa and interpret them in the context of one of the latest kinematic reconstructions. A pre-rift position of the detached continental sliver of the Davie Ridge between Tanzania/Kenya and southeastern Madagascar fits to this kinematic reconstruction without general changes of the rotation poles.

Widespread zoophagy and detection of Plasmodium spp. in Anopheles mosquitoes in southeastern Madagascar

Background Malaria is a top cause of mortality on the island nation of Madagascar, where many rural communities rely on subsistence agriculture and livestock production. Understanding feeding behaviours of Anopheles in this landscape is crucial for optimizing malaria control and prevention strategies. Previous studies in southeastern Madagascar have shown that Anopheles mosquitoes are more frequently captured within 50 m of livestock. However, it remains unknown whether these mosquitoes preferentially feed on livestock. Here, mosquito blood meal sources and Plasmodium sporozoite rates were determined to evaluate patterns of feeding behaviour in Anopheles spp. and malaria transmission in southeastern Madagascar. Methods Across a habitat gradient in southeastern Madagascar 7762 female Anopheles spp. mosquitoes were collected. Of the captured mosquitoes, 492 were visibly blood fed and morphologically identifiable, and a direct enzyme-linked immunosorbent assay (ELISA) was used to test for swine, cattle, chicken, human, and dog blood among these specimens. Host species identification was confirmed for multiple blood meals using PCR along with Sanger sequencing. Additionally, 1,607 Anopheles spp. were screened for the presence of Plasmodium falciparum, P. vivax-210, and P. vivax 247 circumsporozoites (cs) by ELISA. Results Cattle and swine accounted, respectively, for 51% and 41% of all blood meals, with the remaining 8% split between domesticated animals and humans. Of the 1,607 Anopheles spp. screened for Plasmodium falciparum, Plasmodium vivax 210, and Plasmodium vivax 247 cs-protein, 45 tested positive, the most prevalent being P. vivax 247, followed by P. vivax 210 and P. falciparum. Both variants of P. vivax were observed in secondary vectors, including Anopheles squamosus/cydippis, Anopheles coustani, and unknown Anopheles spp. Furthermore, evidence of coinfection of P. falciparum and P. vivax 210 in Anopheles gambiae sensu lato (s.l.) was found. Conclusions Here, feeding behaviour of Anopheles spp. mosquitoes in southeastern Madagascar was evaluated, in a livestock rich landscape. These findings suggest largely zoophagic feeding behaviors of Anopheles spp., including An. gambiae s.l. and presence of both P. vivax and P. falciparum sporozoites in Anopheles spp. A discordance between P. vivax reports in mosquitoes and humans exists, suggesting high prevalence of P. vivax circulating in vectors in the ecosystem despite low reports of clinical vivax malaria in humans in Madagascar. Vector surveillance of P. vivax may be relevant to malaria control and elimination efforts in Madagascar. At present, the high proportion of livestock blood meals in Madagascar may play a role in buffering (zooprophylaxis) or amplifying (zoopotentiation) the impacts of malaria. With malaria vector control efforts focused on indoor feeding behaviours, complementary approaches, such as endectocide-aided vector control in livestock may be an effective strategy for malaria reduction in Madagascar.

Two New Species of Ardisia (Primulaceae) from Southeastern Madagascar

Ardisia sharoniae Manjato, Ravololoman.& Razakamal. and A. vohimenensis Manjato, Ravololoman. & Razakamal. (Primulaceae) are described as new species from southeastern Madagascar, the former from the Ankarabolava and Agnakatrika forests (Atsimo-Atsinanana Region) and the latter from the Vohimena range (Anosy Region). They differ from the four currently recognized Malagasy species of Ardisia Sw. by their leaves with serrate margins and their striking angulate twigs. The two new species differ from one another in several characters of their leaves, inflorescences, and fruits. An illustration and a distribution map are provided for each species. Preliminary assessments of the risk of extinction following the IUCN Red List categories and criteria indicate that both are Endangered. An identification key to the seven species of Ardisia occurring in Madagascar is presented.