Recovery of Phytophthora parvispora from a Sicilian riparian ecosystem.

In a recent survey, carried out in autumn 2017, Phytophthora parvispora has been recovered from Complesso Speleologico Villasmundo - S. Alfio Regional Natural Reserve (Hyblaean Mountains - south-eastern Sicily, Italy) at an altitude of about 100 meters a.s.l. from a chronically declining riparian forest along the course of a torrential stream. Isolates of the species have been obtained by using baiting techniques from rhizosphere soil of a symptomatic willow (Salix pedicellata) tree; the identification was carried out by combining morphological features with sequences of internal transcribed spacer regions (ITS1 and ITS2) and 5.8S gene. Originally identified as a variety of Phytophthora cinnamomi (i.e.: Phytophthora cinnamomi var. parvispora), Phytophthora parvispora has been associated to a severe dieback of Arbutus unedo in Sardinia, Italy, and described as a distinct species in the ITS clade 7a. In Sicily, it has been previously reported only from nurseries in association with cultivated Mandevilla spp. In view of its biological and ecological characteristics, P. parvispora can endure short periods of soil waterlogging and high relative humidity of the air alternating with long periods of drought, typical of the Mediterranean ecosystem where it has been found.