Black mildews belong to a wide range of leaf inhabiting fungal genera, which causes severe damage to the living leaves, affect photosynthetic efficiency, cause physiological imbalances, and reduces the plants’ aesthetic value. During a survey of foliicolous fungi in Vagamon hills of Kerala state’s Western Ghats region, an endemic medicinal plant Xanthophyllum arnottianum was found infected with an undescribed species of black mildew causing fungal genus Echidnodella. Their mycelia are non-appressoriate and devoid of hypostroma. Thyriothecia are oval, ellipsoidal, X or Y shaped, elongated producing eight uniseptate brown coloured ascospores in each bitunicate asci. Echidnodella was distinguished from the allied genus Echidnodes in the absence of paraphyses and from the genera Lembosia and Morenoella in the lack of appressoria (haustoria). This new species, Echidnodella vagamonensis is described and illustrated in detail to provide the consolidated account of the species known on this host genus.