On the 2nd of February 2026, I found a 10 cm long twig covered with perithecia with strikingly long necks (up to 1.5 mm) on Hedera helix. Under the bark was a black stroma.
Perithecia were spherical, up to 440 µm in diameter, black with straight or slightly curved thread-like ostioles up to 1500 µm in length.
Inside the perithecia was a gelatinous content consisting of hundreds of asci (average: 48 x 6.8 µm; Q= 7.2).
Spores (average 12 x 3.1 µm Q = 3.9), usually with septum in the centre and two large droplets in each half.
The reaction of the apical ring in Lugol's or Baral's solution is difficult to determine; Congo red not tested.
While viewing one of the preparations, I found ellipsoidal light brown conidia with the following dimensions: 3.6 x 2.1 µm, no conidiophores found.
Using the key mentioned in the publication by L.E. Wehmeyer(*), I identify the ascomata as D. medusaea (according to Mycobank: current name D. rudis).
This raises two questions:

1. Is Diaporthe rudis correct?
2. Is there a connection with the conidia?

Many thanks in advance,

François Bartholomeeusen

(*)Wehmeyer, L.E. (1933) The British species of the genus Diaporthe Nits. and its segregates. Transactions of the British Mycological Society 17: 237-295D. medusaea