Revision of the soft scale genus Platylecanium (Hemiptera: Coccomorpha: Coccidae), with descriptions of eight new species

The soft scale insect genus Platylecanium Cockerell & Robinson (Hemiptera: Coccomorpha: Coccidae) is member of a group of genera in the tribe Paralecaniinae that have “clear areas” located mediolaterally on the abdomen and polygonal plates on the dorsum delineated by lines of setae and microducts, namely, Paralecanium Cockerell, Discochiton Hodgson & Williams, Insularicoccus Hodgson & Williams and Platylecanium. The species in Platylecanium have never been revised and their character-states are mostly poorly understood as most were described a long time ago and are currently unrecognisable.

The purpose of this revision is to: (i) clarify the morphological boundaries of the genus, and (ii) outline how it differs from the other closely similar genera. The present revision, based on the morphology of the adult females, redescribes and illustrates 7 of the 10 species previously included in the genus; unfortunately, type material of three species (P. cyperi Takahashi, P. elongatum Takahashi and P. riouwense Takahashi) was not available.

Eight species are described as new, namely: P. coelogyne Hodgson, P. dendrobii Hodgson, P. eastopi Hodgson, P. faveolatum Hodgson, P. palmae Hodgson, P. sarawakense Hodgson, P. vanda Hodgson and P. watsoniae Hodgson spp. nov. The second-instar male and second-instar female of P. vanda are also described and illustrated. In addition, it is argued that asymmetry should not be used as a species diagnostic character in the Coccidae, so P. cocotis Laing is here considered to be a junior synonym of P. asymmetricum Morrison syn. nov. as it appears to be otherwise identical.

Keys are provided for separating: (i) Platylecanium from the closely related genera Discochiton, Insularicoccus and Paralecanium, based on adult female morphology; and (ii) the 17 species now recognised in the genus. A lectotype is designated for P. fusiforme Green.