Gymnosporangium confusum Plowright, 1889

on woody Rosaceae

Gymnosporangium confusum: gall on Crataegus monogyna

Crataegus monogyna (underside of the leaf); Amsterdam, Diemerpark

Gymnosporangium confusum: upperside of gall with spermogonia

Mespilus germanica, Amstelveen, Thijssepark: upperside, with spermogonia

Gymnosporangium confusum: peridium sculpture

surface of the inner wall of the peridium

Gymnosporangium confusum: aeciospore

aeciospore

Gymnosporangium cf confusum on Crataegus monogyna

Crataegus monogya, Gramsbergen, Holthone © Arnold Grosscurt; identification tetative

Gymnosporangium cf confusum

gall sliced

gall

Aecia 1-2 mm high. The walls of the peridium cells have numerous, somewhat wavy length ridges, which distinguish this species from G. clavariiforme.

Aecia can also develop on young shoots, and then induce strong malformations. Gäumann describes this for G. confusum only, but it cannot be excluded that other Gymnosporangium‘s cause similar galls (Brian Spooner in litt.).

spermogonia, aecia

woody Rosaceae (Maloideae), oligophagous

Chaenomeles japonica; Cotoneaster integerrimus, melanocarpus, nebrodensis, niger, nummularius; Crataegus azarolus, elliptica, grandiflora, laciniata, laevigata, monogyna, orientalis subsp. szovitsii, pentagyna, pinnatifida, sanguinea, tanacetifolia; Cydonia oblonga; Mespilus germanica; Pyracantha coccinea; Pyrus communis; Sorbus aucuparia, latifolia, torminalis.


on Juniperus

gall

only telia, on swellings of the branches, ± conical, up to 8 mm high, yellowish brown when moist. Teliospores in two forms: hyaline, thin-walled, stout, and brown, thick-walled, slender; spores apically rounded. They are two-celled, each cell with 2 germination pores close to the separation wall; measurements 19-26 x 30-48 µm, pedicel up to 120 µm.

telia

Cupressaceae, monophagous

Juniperus sabina.

Not on J. communis.

synonyms

Gymnosporangium oxycedri Bresadola, 1903; G. tauricum Eriksson, 1919.

notes

In connection with G. confusum en sabinae, Redfern & Shirley note that once in the UK on Juniperus chinensis another rust has been found, viz. Gymnosporangium asiaticum Miyabe 1904.

references

Bahcecioglu & Kabaktepe (2012a), Brandenburger (1985a: 29), Buhr (1964b), Dauphin & Aniotsbehere (1997a), Dervis, Dixon, Doğanlar & Rossman (2010a), Erdoğdu, Hüseyin & Suludere (2010a), Gäumann (1959a), González-Fragoso (1925a), Helfer (2005a), Henderson (2000a, 2004a), Klenke & Scholler (2015a), Llorens i Villagrasa (1984a), Poelt & Zwetko (1997a), Preece & Hick (1994a), Redfern & Shirley (2011a), Roskam (2009a), Termorshuizen & Swertz (2011a), Tomasi (2014a), Vanderweyen & Fraiture (2008a), Wilson & Henderson (1966a), Woods, Stringer, Evans & Chater (2015a).

mod 10.viii.2018