Lectera colletotrichoides (Chilton) P.F. Cannon

Cannon, Paul F., Buddie, Alan G., Bridge, Paul D., Neergaard, Eigil de, Luebeck, Mette & Askar, Mohamed M., 2012, Lectera, a new genus of the Plectosphaerellaceae for the legume pathogen Volutella colletotrichoides, MycoKeys 3, pp. 23-36 : 26-27

Lectera colletotrichoides (Chilton) P.F. Cannon comb. nov.

Volutella colletotrichoides Chilton, Mycologia 46: 801 (1954), basionym.

Volutella colletotrichoides var. setosa Chilton, 46: 801 (1954).

Description.

Conidiomata formed at the apex of a short peg-like vegetative structure that is erumpent through host tissues, 80-350 µm diam, cushion-shaped to almost globose, with a compact palisade of conidiogenous cells usually surrounded by setae. Setae variably produced, with some conidiomata dark grey in coloration due to copious setae while others are pale pink or flesh-coloured with few or no setae; 50-130 µm in length, 3-6 µm in diam at the base, gradually tapering, golden to dark brown, smooth or sparsely verrucose, 2- to 3-septate, the apex acute. Conidiogenous cells 15-32 × 3-5 µm, cylindrical or slightly tapering with the apex rounded, proliferating percurrently with inconspicuous periclinal thickening and sometimes a minute collarette. Conidia inoculated onto Medicago sativa stem (6.5-) 7-10 (-11.5) [mean 8.35 µm, sd 0.73, n = 140] × 2.5-3 (-3.5) µm [mean 2.67 µm, sd 0.24, n = 140], mean length/width ratio 3.14: 1, cylindrical to cylindric-fusiform or navicular, the ends acute, slightly usually inaequilateral with one longitudinal face ± flat, hyaline, aseptate, smooth-walled, without a gelatinous sheath or appendages. Cultures on PCA and PDA at 25°C under alternating daylight/near UV growing moderately slowly, reaching 25-30 mm after 7 d, bright orange with a waxy appearance, the central part becoming brownish after 14 d, aerial mycelium poorly developed. Conidiomata absent or poorly developed, with setae fewer, narrower, shorter and less pigmented than in colonies on host tissue, and conidiogenous cells often formed singly at the apex of vegetative hyphae. Conidia 6.5-9 (-10.5) [mean 7.41 µm, sd 0.68, n = 100] × 2-3 µm [mean 2.43 µm, sd 0.22, n = 100], mean length/width ratio 3.07: 1, similar in appearance to those formed after inoculation on Medicago sativa stems. Appressoria 4.5-8 × 4-6.5 µm, circular to ovate with entire margins, dark brown. Sclerotia not observed.

Typification.

USA: Iowa, Ames, on stems of Medicago sativa , Oct. 1954, J. Chilton(ISC 217496, lectotype, here designated; K(M) 176269, isolectotype of Volutella colletotrichoides ). USA: Iowa, Ames, on stems of Medicago sativa , Oct. 1954, J. Chilton (ISC 217482, lectotype, here designated; K(M) 176270, isolectotype of Volutella colletotrichoides var. setosa). Other authentic material: same collection data, ISC 217488, ISC 217497 and ISC 217498 - syntypes of Volutella colletotrichoides ; same collection data, ISC 217483 and ISC 217484 - syntypes of Volutella colletotrichoides var. setosa.

Host species.

Associated with Asteraceae ( Xanthium spinosum ), Fabaceae ( Cicer arietinum , Glycine max , Lotus corniculatus [Chilton, 1954], Medicago falcata [Chilton, 1954], Medicago sativa , Phaseolus vulgaris , Pisum sativum , Senna sophera , Trifolium hybridum [Chilton, 1954], Trifolium pratense [Chilton, 1954], Trifolium subterraneum , Vicia faba and Vigna unguiculata ), Lamiaceae ( Tectona grandis ), Poaceae ( Agrostis stolonifera , Hordeum vulgare , Triticum sp. and Zea mays ), Solanaceae ( Capsicum annuum ) and Violaceae ( Viola sp.).

Distribution.

Africa (Democratic Republic of the Congo, Egypt, Ethiopia, Morocco, Nigeria, South Africa [http://www.cbs.knaw.nl/], Zimbabwe [unpublished IMI record without voucher material]). Asia (India, Kuwait [unpublished IMI record without voucher material], Turkey [ Eken et al. 2002]). Australasia (Australia, New Zealand). Europe (United Kingdom). North America (USA: Iowa, presumed introduced and now eradicated). South America (Argentina, Brazil).

Interactions.

Strains of Lectera colletotrichoides have been demonstrated to be pathogenic towards a range of Fabaceae species, but they are also commonly found associated with plants from other families and isolated from soil and plant litter. It also grows well in standard agar culture. It therefore can be presumed to exist (and probably grow actively) as a saprobe, and it is possible that the non-legume isolates originate from soils used to grow legumes in rotation.

Conservation assessment.

The species as currently circumscribed has not been reported since 2002 but is very widely distributed, is associated with a wide range of plant taxa and apparently can exist as a saprobe in soil and leaf litter without a direct plant association. It does not appear to be an economically important pathogen except perhaps in limited circumstances. However, as there is a high risk of confusing disease symptoms of Lectera colletotrichoides with those caused by Ascochyta rabiei , the economic impact of Lectera colletotrichoides may be underestimated. It may be sensitive to agricultural pesticides, but is unlikely to face major threats from specific eradication measures. Its conservation status ( Dahlberg and Mueller 2011) must be considered as Data Deficient, but is probably of Least Concern.

Specimens examined.

Africa: DRC: Mulungu, causing leaf spot of Glycine soja , comm. 28 Mar. 1978, D.J. Allen (IMI 226829a). Egypt: Ismailia, Salheia, isol. ex Cicer arietinum , 1988, M. Askar CP2035 (IMI 332702). Ethiopia: unlocalized, isol. ex seed of Phaseolus vulgaris , undated, s. coll. (IMI 366179). Morocco, unlocalized, isol. ex Capsicum annuum , Feb. 1986, Hasmi (IMI 303685). Nigeria: unlocalized, isol. ex Vigna sinensis , comm. 22 May 1972, R. Williams 4150 (IMI 166385); same data, R. Williams 4152 (IMI 166394). Asia: India: Rajupur, Mirzapur, on and isol. ex Senna sophera , Apr. 1982, S.N.P. Chaurasia SNPC-5 (IMI 269185); Jabalpur, isol. ex leaf litter of Tectona grandis , comm. 5 Feb. 1986, Jamaluddin (IMI 265505). Australasia: Australia: New South Wales, unlocalized, isol. ex Agrostis stolonifera , comm. 26 Jan. 1983, G. Schultz (IMI 275263); Western Australia: Esperance, isol. ex Trifolium subterraneum , comm. 13 Jul. 1972, R.F. Doepel (IMI 167533); New Zealand: Wellington, isol. ex Hordeum vulgare , comm. 11 Apr. 1980, L. Chong 18P14 (IMI 247318). Europe: United Kingdom: Kent, nr Ashford, Wye College, comm. 24 Oct. 1979, D.W. Parry 6 (IMI 242382); same locality, isol. ex Zea mays , comm. 24 Oct. 1979, D.W. Parry 11 (IMI 242387). South America: Argentina: Córdoba, San Francisco, Monte Cristo, isol. ex stem of Xanthium spinosum , 1995, s. coll. (IMI 368065). Brazil: unlocalized, isol. ex soil, comm. 18 Feb. 1982, J. Diehl & E. Reis 46/81 (IMI 265740).