The Hemitarsonemus species recently found in the Netherlands on Platycerium alcicorne is H. ganeo
In the EPPO RS 2016/054, the presence of Hemitarsonemus tepidariorum (Acarida: Tarsonemidae) was reported for the first time in the Netherlands. The mite had been found on plants for planting of Platycerium alcicorne (Polypodiaceae) in 1 greenhouse located at ‘De Kwakel’ in the municipality of Uithoorn. However, further verification of specimens by experts showed that the first identification of the pest as Hemitarsonemus tepidariorum was probably incorrect (EPPO RS 2016/132). Further investigations have now confirmed that the identity of the pest is Hemitarsonemus ganeo. In addition to the initial finding recorded in November 2015 on P. alcicorne, the pest was detected in early September 2016 on several ferns (Athyrium filix-femina, Dryopteris carthusiana, Dryopteris filix-mas, and Polypodium vulgare) growing outdoors in public green and forests near Ede and Wageningen (approximately 100 km away from the first finding site). No visible damage was observed on outdoor ferns as opposed to greenhouse P. alcicorne plants. H. ganeo was first described in Poland on fern species (Athyrium filix-femina, Dryopteris dilatata, Dryopteris filix-mas) present in forest habitats (Magowski, 2012). H. ganeo is closely related to H. tepidariorum which has been recorded in the USA, United Kingdom and Costa Rica before, but its world distribution is highly uncertain. Both species can cause damage on various fern species. Considering the fact that H. ganeo occurs outdoors in the Netherlands and in Poland, no official eradication measures are taken. At the place of production, the grower has destroyed all affected P. alcicorne plants.
The pest status of Hemitarsonemus ganeo in the Netherlands is officially declared as: Present, in all parts of the Member State concerned.
Sources
NPPO of the Netherlands (2016-09).
Magowski WŁ (2012) Two new species and a new subgenus of tarsonemid mites (Acari: Heterostigmatina: Tarsonemidae) from ferns in Poland. Zoological Studies 51(4), 512-525. http://zoolstud.sinica.edu.tw/Journals/51.4/512.pdf