Puccinia megalospora (Orton) Arthur & Johnston (1918: 152)

De Carvalho-Junior, Anibal A. & Hennen, Joe F., 2018, Puccinia on Ipomoea (Convolvulaceae) in Neotropics, Phytotaxa 344 (2), pp. 133-148 : 142

9. Puccinia megalospora (Orton) Arthur & Johnston (1918: 152) .

≡ Allodus megalospora Orton (1916: 198) .

≡ Puccinia megalospora (Doidge) Sacc. & Trotter in Saccardo (1925: 713) (nom. illegit.).

Type:― MEXICO. Oaxaca, 17 Oct 1899, on Ipomoea murucoides Roem. & Schult., E.W.D. Holway 3643. Figure 3 D− F (Holotype).

Spermogonia and aecia unknown. Uredinia ( Aecidium type) mainly on the abaxial side of leaves, occurring singly or in small groups, 0.2–0.5 mm in diameter, cylindrical; peridium up to 0.6 mm high, white, erose at first, becoming lacerate; peridial cells 31–45 × 16–25 μm, rhomboidal, the outer facing wall 4–6 μm thick, striate, the inner facing wall 6–10 μm thick, rather coarsely verrucose; urediniospores catenulate, 23–34 × 19–28 μm, globoid or broadly ellipsoid; wall 1.5–2 μm thick, finely and closely verrucose, colorless. Telia mostly on the adaxial side of leaves, scattered singly or in groups, often arising opposite or around or among the uredinia, 0.2–0.6 mm in diameter, circular in outline, early naked, often becoming confluent and forming large sori up to 5 mm across, pulverulent, blackish-brown, ruptured epidermis rather conspicuous; teliospores 48–70 × 23–32 μm, ellipsoid, narrowed or rounded above, rounded below, slightly constricted at the septum, wall chocolate-brown, 3–4 μm thick at sides, 9–15 μm thick above, somewhat paler at apex, pedicel upto 115 μm long, stout, tinted next to spore ( Arthur and Orton 1921). Life cycle (?/?, IIcv, III).

Specimen examined (Holotype)― MEXICO. Oaxaca: Oaxaca, 17 Oct 1899, on Ipomoea murucoides Roem. & Schult., E.W.D. Holway 3643 (PUR36107!).

Distribution ― Puccinia megalospora is known from Mexico, Cuba ( Arthur & Johnston 1918), Caribean Islands (West Indies) and South America ( Hennen and Cummins 1973; Farr & Rossman 2015).

Notes ― Puccinia megalospora (Doidge) Sacc. & Trotter ( Saccardo 1925) is an illegitimate name since the authors suggested the name in 1925, but Arthur & Johnston (1918) had already suggested it, both based on Allodus megalospora ( Orton 1916) . Arthur and Johnston (1918) suggests that P. megalospora resembles P. crassipes but has more larger aeciospores and teliospores more thickened at apex. Urban (1990) complements differentiation showing that P. megalospora has two germ pores at the proximal cells of teliospores. In this sense, we prefer to maintain separation of the species. Our microscopy observations were very similar to those of Arthur & Orton (1921) and although these authors have suggested that P. megalospora is synonymous of P. macrocephala , we understand that there are enough differences to keep them separate.

Figures

FIGURE 3. A−C. Puccinia jalapensis (Holotype). A−B. Urediniospores. A. Median focus. B. Surface focus. C. Line drawing of Teliospores.D−F.P. megalospora (Holotype). D−E. Urediniospores. D. Median focus. E. Surface focus.F.Teliospores.G−H. P. nocticolor (Paratype). G. Urediniospores in median focus above and in surface focus below. H. Teliospores in median focus above and in surface focus below. Bars:A−C, G=10 μm; D−F, H=20 μm.