Greece, Rhodes Island, 3.5 km NE Archangelos, Tsambika, on path to monastery, northeast slope, 36°14'03"N, 28°09'19"E, 90 m a.s.l, on Anthemischia, 26 Apr. 2017, V. Kummer. Holotype GLM-F112531, isotype Herbarium V. Kummer P 1971/chia4; ITS sequence GenBank MH399758.

From the host plant genus Anthemis.

Sori in swollen and distorted flower heads and peduncles; spore ball mass initially white, later reddish-brown, granular to powdery; spore balls subglobose to ellipsoidal, rarely ovoid, mostly regular in shape, (31–) 36–41–47 (–52) × (28–) 31–38–44 (–50) µm, length/width ratio 0.9–1.1–1.2 (n=30), under light microscopy yellowish-brown to pale yellowish-brown, composed of 2–10 (–12) loosely united spores that separate easily; spores ellipsoidal, subglobose, ovoid or cuneiform, (18–) 20–21–23 (–25) × (14–) 17–18–20 (–23) µm, length/width ratio of 1.1–1.2–1.4 (n=100), with flattened contact surfaces and rounded exposed surfaces; wall at contact surface up to 0.5 µm thick, wall at free surface up to 3 µm thick, densely verrucose with warts 0.5–1 µm high, often confluent and sometimes irregular.

Anthemischia.

Greece.

Thecaphoraanthemidis has sori in the flower heads and the peduncles, which differentiates it from the following species that produce pustules, galls or swellings on the stems of Asteraceae: Th.ambrosiae, Th.denticulata, Th.heliopsidis, Th.hennenea, Th.melampodii, Th.mexicana, Th.neomexicana, Th.piluliformis, Th.polymniae, Th.pulcherrima, Th.pustulata, Th.smallanthi and Th.spilanthis. Four of the seven previously known species of Thecaphora that infect the flower heads of Asteraceae, namely Th.arnicae, Th.burkartii, Th.californica and Th.cuneata have firmly united spores that only separate after considerable pressure, which differentiate them from Th.anthemidis that has loose spore balls. Further, Th.arnicae (spore balls comprised of up to 25 spores), Th.californica (6–20 spores) and Th.solidaginis (8 to 50 or more spores) have larger spore balls with larger numbers of spores than Th.anthemidis. The spores of Th.cuneata are radially arranged within the spore balls and Th.burkartii has spores with an outer wall 5–9 µm thick, which is more than three times thicker than in Th.anthemidis. Thecaphoralagenophorae and Th.trailii are morphologically most similar to Th.anthemidis. Thecaphoralagenophorae is only known to infect Solenogynegunnii (tribe Astereae) in Australia (Vánky 2012). Thecaphoratrailii infects species of Carduus, Cirsium and Saussurea (Asteraceae, tribe Cynareae, Carduoideae) (Vánky 2012) and further differs from Th.anthemidis by having smaller spore balls (12–30 µm) and fewer spores (2–8) per spore ball.