Phytophthora has been rebuilt to fix security-related problems and to restore GIS tools. These tools allow users to visualize the geospatial, temporal, and environmental contexts of Phytophthora discoveries. The next phase is to update species information and add data derived from large-scale surveys. If you have suggestions and requests to make the database better, please contact Seogchan Kang (sxk55@psu.edu).
* This species has not yet been formally described and should be treated as such.
Genus wide phylogeny for Phytophthora using four mitochondrial loci (cox2, nad9, rps10 and secY; 2,373 nucleotides). Maximum likelihood branch lengths shown. Numbers on nodes represent bootstrap support values for maximum likelihood (top), maximum parsimony (middle) and Bayesian posterior probabilities as percentages (bottom). Nodes receiving significant support (>95%) in all analysis are marked with an asterisk (*). Scale bar indicates number of substitutions per site.(Martin, Blair and Coffey, unpublished).
[ Click the tree to enlarge it. ]
Phytophthora taxon ‘aquatilis’ is a provisional species name for a single isolate that was recovered only once from Fishpond Creek in central Virginia during a statewide survey of six streams sampled in Apr, May, Jun, Jul and Sep 2006 (Hong et al. 2012). A formal taxonomic description is awaiting recovery of additional isolates. Phylogenetically this taxon is in clade 2 with P. multivesiculata as the closest species.
1. Sporangia
Sporangia were semi-papillate and caducous with variable pedicels 0–75.4 μm. Most sporangia were ovoid, 26.2–66.1(45.9) μm long and 19.1–39.6(29.7) μm wide. The sporangial length to width ratio was approximately 1:6. Irregular sporangia shapes occasionally occurred. A few sporangia had more than one papilla or appeared curved or even sickle-shaped. Most sporangia grew primarily on unbranched sporangiophores and some were in a simple sympodium. Lateral attachment to sporangiophore occurred and direct germination of sporangia was common.
2. Chlamydospores
3. Sex Organs
The monosporic culture of P. taxon ‘aquatilis’ produced abundant sexual structures on carrot agar and sporangia on CV8A. Oogonia were globose (FIG. 7A–K). Their diameters were 27.4– 42.5(38.2) μm. Most antheridia were paragynous with variable attachments to oogonium. Amphigynous attachments occurred infrequently (approximately 6%). Oospores were plerotic, 23.6–38.5(34.1) μm. Oospore wall index was 18– 60%, averaging 33%.
4. Growth Temperatures
Optimal temperature is 20° C, grows at 5° C but not at 35° C.
5. Growth Characteristics in Culture
6. Distinguishing Characteristics
This taxon can be differentiated easily from other Phytophthora species in Clade 2 by molecular analyses and morphology. Specifically, P. taxon ‘aquatilis' can be separated from P. multivesiculata by its paragynous antheridia, caducous sporangia and the absence of hyphal swellings. Caducous sporangia also separate this taxon from P. bisheria , P. citricola, P. multivora, P. elongata and P. taxon 'elongata'-like. In addition, P. taxon ‘aquatilis' readily can be distinguished from other species producing caducous sporangia. For example, P. siskyouensis produces smaller oogonia/oospores and larger sporangia and has a lower maximal growth temperature. P. botryosa, P. capsici, P. colocasiae, P. meadii, P. tropicalis and P. frigida are heterothallic and they all produce papillate sporangia, with the exception of P. colocasiae, which produces semipapillate sporangia.
Phytophthora taxon \'aquatilis\' is pathogenic on rhododendron.
Hong, C., Richardson, P. A., Hao, W., Sita R. Ghimire, S. R., Moorman, G. W., Lea-Cox, J. D., Ross, D. S. and Kong, P. 2012. Phytophthora aquimorbida sp. nov. and Phytophthora taxon ‘aquatilis' recovered from irrigation reservoirs and a stream in Virginia, USA. Mycologia In Press doi:10.3852/11-055
This species page was adapted from Hong et al. (2012)
Isolate list