Andricus rhyzomae (Hartig, 1843)

on Quercus, agamous generation

galls (from Houard, 1908a)

Quercus robur (root collar of a young tree), Drenthe, Beilen, Schepping in Holthe, 10.vii.2021 © Eef Arnolds

another image

Quercus robur, Elspeet, landgoed Staverden © Hans Jonkman: young, still fleshy gall

Quercus robur, De Schipborg, Aa en Hunze © Arnold Grosscurt

two tiny galls

gall

Galls, mostly several together, on the bark mainly near the base of a trunk. Fresh gall are semi-globular, 2-5 mm high, and have a fleshy red outer layer. After this has been eroded away, a low, woody, truncate cone remains with a radial striation on its base, and a large exit opening at its tip.

host plants

Fagaceae, monophagous

Quercus lusitanica, petraea, pubescens, pyrenaica, robur.

notes

for over more than half century is is assumed that A. rhyzomae is the agamous generation of Andricus testaceipes, but experimental proof is still being awaited. In case the synonymy might be proven, then testaceipes is the oldest, hence valid, name.
Similarly, it is broadly assumed that Andricus nodifex is the sexual generation of rhyzomae; here also experimental confirmation is waiting.

synonyms

Andricus rhizomae (Schenck, 1863).

references

Buhr (1965a), Cerasa (2015a), Dauphin & Aniotsbehere (1997a), Eady & Quinlan (1963a), Hellrigl (2009a), Hellrigl & Bodur (2015a), Houard (1908a), Kwast (2014a), Meika (2006a), Melika, Csóka & Pujade-Villar (2000a), Redfern & Shirley (2011a), Roskam (2009a), Tavares (1905a), Tomasi (2014a), Williams (2010a).