Table 3.
Morphological characters and dimensions (µm), cardinal temperatures (°C) and temperature-growth relations (mm/d) of eight new Halophytophthora species. Most discriminating characters are highlighted in bold.
| H. brevisporangia | H. celeris | H. frigida | H. lateralis | H. lusitanica | H. macrosporangia | H. sinuata | H. thermoambigua | |
|---|---|---|---|---|---|---|---|---|
| No. of isolates | 3a | 3a | 7a | 4a | 6a | 7a | 6a | 11a |
| Sporangia | ovoid 86 %, obpyriform, (distorded, ellipsoid, obturbinate) | ovoid 60 %, obpyriform, (subglobose, limoniform) | obpyriform 83 %, ovoid, (distorted, obturbinate, limoniform, ellipsoid) | ovoid 95% (sub-globose, ovoid-obpyri-form, distorted) | obpyriform 54 %, ovoid (ellipsoid, limoniform, obturbinate, distorted) | obpyriform 56 %, ovoid, (subglobose, distorted, peanut-shaped) | obpyriform 85 %, ovoid, (distorted, limoniform), often asymmetric | obpyriform 50 %, ovoid, (limoniform, ellipsoid, ampulliform, distorted) |
| l×b mean | 57.6±10.9 × 42.1±8.8 | 60.5±12.5 × 46.1±10.4 | 80.4±19.3 × 50.1±13.8 | 75.9±16.1 × 52.4±12.5 | 84.0±15.8 × 54.3±10.6 | 97.5±24.8 × 55.0±14.8 | 74.1±19.5 × 44.0±12.6 | 75.3±15.7 × 48.1±9.7 |
| range of isolate means | 54.7–59.7 × 39.9–45.9 | 56.2–64.6 × 43.9–47.3 | 72.7–85.7 × 44.5–57.1 | 67.7–89.5 × 45.4–63.6 | 76.2–95.4 × 47.1–60.2 | 76.8–118.9 × 42.9–67.4 | 56.9–82.1 × 32.5–51.4 | 69.2–83.2 × 40.3–57.1 |
| total range | 31.2–101.4 × 20.9–78.8 | 29.4–92.8 × 20.8–78.0 | 32.4–150.7 × 18.8–98.1 | 41.6–122 × 22.8–100.3 | 40.5–162.5 × 25.4–86.3 | 58–186.7 × 32.3–106.3 | 28.1–129.2 × 19.8–89.5 | 43.4–185.3 × 25.3–83.9 |
| l/b ratio | 1.4 ± 0.1 | 1.3 ± 0.1 | 1.6 ± 0.3 | 1.5 ± 0.2 | 1.6 ± 0.3 | 1.8 ± 0.4 | 1.7 ± 0.3 | 1.6 ± 0.3 |
| apexb | non-papillate, often pointed, 2 apices not observed | non-papillate, often pointed, 2 apices rare | non-papillate, pointed to protuberant, some curved or 2 apices | non-papillate or semi-papillate, sometimes pointed or 2 apices | non-papillate or rarely semipapillate, some-times 2 apices or curved | non-papillate, some-times pointed or 2 apices | non-papillate, often pointed, sometimes 2 apices | non-papillate, pointed to protuberant, some curved, 2 apices common |
| special features | basal plug frequent, lateral attachment occasionally | protruding basal plugs, sometimes intercalary or lateral attachment (13 %) | frequently intercalary or lateral attachment | lateral attachment 41.5 %, sometimes protruding basal plug | some with lateral attachment, hyphal beak or basal plug | sometimes lateral attachment, small vacuoles, swelling close to base | lateral attachment 31.4 %, often 1 or more vacuoles | some intercalary, lateral attachment 38.4 %, basal plug common |
| external proliferation | common, lax sympodia | rare | infrequent | infrequent | rare | infrequent | rare | infrequent |
| zoospore release | through semi-persistent elongated vesicle | through semi-persistent elongated vesicle | through semi-persistent elongated vesicle | through semi-persistent elongated vesicle | through semi-persistent elongated vesicle | through semi-persistent elongated vesicle | direct or through semi-persistent vesicle | through semi-persistent elongated vesicle |
| exitpores | 9.8 ± 1.7 | 10.5 ± 1.6 µm | 9.5 ± 1.6 | 12.6 ± 2.4 | 10.6 ± 2.1 | 10.3 ± 1.7 | 8.9 ± 1.5 | 10.3 ± 2.3 |
| zoospore cysts | 7.9 ± 0.7 | 8.8 ± 0.8 | 9.1 ± 2.0 | 7.9 ± 0.7 | 8.2 ± 0.9 | 8.2 ± 2.1 | 7.5 ± 1.1 | 8.6 ± 0.9 |
| Breeding system | sterile | sterile | homothallic | sterile | sterile | homothallic | homothallic | sterile |
| Oogonia | – | – | smooth-walled, some slightly ornamented | – | – | smooth-walled | wavy to slightly verru-cose goldenbrown wall | – |
| mean diam | 47.8 ± 4.0 | 48.2 ± 4.6 | 54.2 ± 3.8 | |||||
| range of isolate means | 43.0–49.9 | 46.7–49.2 | 51.6–55.6 | |||||
| total range | 32.0–58.6 | 18.4–58.7 | 39.4–64.3 | |||||
| Oospores | – | – | 99.3 % plerotic | – | – | 100 % plerotic | 95 % plerotic | – |
| mean diam | 45.3 ± 4.1 | 43.7 ± 4.2 | 47.5 ± 3.7 | |||||
| total range | 29.1–54.9 | 30.1–54.5 | 33.9–57.6 | |||||
| wall diam | 2.2 ± 0.5 | 1.7 ± 0.4 | 2.9 ± 0.6 | |||||
| oospore wall index | 0.26 ± 0.05 | 0.22 ± 0.04 | 0.32 ± 0.05 | |||||
| Abortion rate | 22.7 % (2–50 %) | 41.5 % (14–82 %) | 4.2 % (0–13 %) | |||||
| Antheridia | – | – | paragynous, mostly intricate stalks | – | – | paragynous intricate stalks occasionally | paragynous, very rarely intricate stalks | – |
| size | 18.3±3.6 × 10.3±2.7 | 15.2±3.1 × 7.8±1.7 | 14.9±2.8 × 11.6±1.8 | |||||
| Hyphal swellings | – | infrequent, triangular | rare | – | rare | infrequent | – | infrequent; 33.8 ± 9.5 |
| Hyphal aggregations | – | common | – | – | – | – | – | – |
| Colonies on sV8A | faintly radiate, limited cottony mycelium | uniform, limited cottony | faint radiate to petaloid, limited aerial or cottony | stellate, limited aerial mycelium | petaloid-faintly petaloid, limited aerial mycelium | faint stellate, limited aerial, submerged edge | uniform, limited aerial mycelium | stellate-radiate or petaloid, limited aerial |
| Colonies on sCA | uniform, limited cottony mycelium | uniform, limited cottony | similar to sV8A | faintly petaloid, limited aerial mycelium | petaloid-faintly petaloid, limited aerial mycelium | uniform, limited aerial, submerged edge | faintly radiate, limited aerial mycelium | stellate-radiate or petaloid, limited aerial |
| Colonies on sPDA | uniform or petaloid, dense-felty appressed | faint petaloid – petaloid, felty, cottony margin | faint petaloid, felty-cottony, submerged edge | dense-felty, uniform | felty, uniform, ring of collapsed aerial mycelium | stoloniferous-petaloid, appressed-submerged | faintly petaloid, cottony | felty, petaloid |
| Maximum temperature | 32.5 | 32.5 | 25 | 32.5 | 32.5 | 27.5 | 27.5 | 32.5 |
| Optimum temperature | 25 | 25 | 15 (20) | 25 | 25 (20, 27.5) | 15, (20), 25 | 25 | 25 (20, 27.5) |
| Growth rate sV8A 20 °C | 18.5 ± 1.3 | 20.4 ± 0.7 | 8.3 ± 2.3 | 10.3 ± 0.7 | 7.3 ± 0.6 | 4.2 ± 1.1 | 14.9 ± 0.3 | 5.2 ± 1.2 |
| Growth rate sCA 20 °C | 16.7 ± 0.5 | 17.0 ± 0.1 | 9.4 ± 0.8 | 12.0 ± 0.4 | 6.9 ± 0.8 | 5.1 ± 1.4 | 12.8 ± 0.1 | 5.2 ± 1.4 |
| Growth rate sPDA 20 °C | 13.3 ± 1.4 | 15.7 ± 0.3 | 5.7 ± 0.6 | 9.8 ± 0.3 | 6.7 ± 0.4 | 4.1 ± 1.1 | 13.3 ± 0.4 | 5.0 ± 2.1 |
a Numbers of isolates included in the growth tests: H. thermoambigua - 5; H. lusitanica - 5; H. lateralis - 4; H. frigida - 5; H. sinuata - 5; H. macrosporangia - 5; H. brevisporangia - 3; H. celeris - 3.
b Apex in all 8 new Halophylefththora species becoming pseudo-papillate during zoospore differentiation due to the shrinkage of the proleftlasm away from the apex.
– = character not observed; n.a. = not available.