A new species in the Mycosphaerellaceae from Cecidomyiidae leaf galls on Avicennia marina in South Africa.

During studies to investigate the health of mangrove trees in South Africa, high numbers of Avicennia marina were found with leaf galls caused by unidentified adults and larvae of midges (Cecidomyiidae). Fungal fruiting structures were commonly observed on the abaxial areas of the galls. To determine the identity of the fungi associated with the gall midges, phylogenetic analyses using multigene sequence data were used. The nuclear large subunit (LSU), internal transcribed spacer (ITS), and a portion of the actin gene region (ACT), were amplified and analyzed. The results revealed that the fungal fruiting structures represent a new taxon in the Mycosphaerellaceae described here as Zasmidium mangrovei sp. nov. This is the first report of a species in the Mycosphaerellaceae associated with cecidomyiid leaf galls on A. marina.

Endophytic Botryosphaeriaceae, including five new species, associated with mangrove trees in South Africa.

Little is known regarding the fungi, especially fungal pathogens, associated with mangroves in Africa. This includes fungi in the Botryosphaeriaceae that comprise numerous opportunistic, stress-associated pathogens often associated with trees affected by environmental and anthropogenically generated stresses, such as those affecting mangroves. We investigated the occurrence of endophytic Botryosphaeriaceae along the entire distribution of mangroves in South Africa. Asymptomatic branches were collected from ten localities and six mangrove species. Isolates resembling species of Botryosphaeriaceae were identified based on multi-gene sequence data of the internal transcribed spacer regions (ITS), including the 5.8S nrRNA, the beta-tubulin (tub2), partial translation elongation factor 1-alpha (tef1-α), and DNA-directed RNA polymerase II second largest subunit (rpb2) gene regions. Inoculation trials were conducted on healthy branches of Avicennia marina and Bruguiera gymnorrhiza to evaluate the potential pathogenicity of the collected species. Fourteen species in the Botryosphaeriaceae belonging to four genera, Botryosphaeria, Diplodia, Lasiodiplodia, and Neofusicoccum were collected, including five new species. Neofusicoccum was the most prevalent genus followed by Lasiodiplodia, with species of Diplodia and Botryosphaeria being the least frequent. The inoculation studies revealed that one of the new species, Lasiodiplodia avicenniae is highly pathogenic to A. marina and could pose a threat to the health of these trees.

Ophiostomatoid fungi associated with mangroves in South Africa, including Ophiostoma palustre sp. nov.

Mangrove trees are continuously under stress due to environmental and/or anthropogenic pressures, which expose them to attack by pathogens, compromising their survival. Ophiostomatoid fungi cause sap stain and diseases of a wide spectrum of tree species globally. These fungi infect trees through natural, insect, animal and/or human made wounds. During routine surveys of mangrove trees in South Africa, wounds on branches and stems of Avicennia marina were regularly monitored for the presence of ophiostomatoid fungi at ten study sites in the country. The stems of four mangrove species, A. marina, Bruguiera gymnorrhiza, Rhizophora mucronata and Barringtonia racemosa were also wounded and evaluated for the appearance of these fungi. Ophiostomatoid fungi were obtained from the mangrove associate B. racemosa, but not from any of the true mangroves. Analyses of DNA sequence data for the internal transcribed spacer, ß-tubulin, calmodulin and translation elongation factor gene regions revealed that the fungi isolated from the wounds on B. racemosa belong to three species in the Ophiostomataceae, including a new taxon described here as Ophiostoma palustre sp. nov. These results suggest that the mangrove associate B. racemosa is more prone to colonization by ophiostomatoid fungi than the true mangroves.