Platylecanium riouwense Takahashi, 1951

Hodgson, Chris, 2025, Revision of the soft scale genus Platylecanium (Hemiptera: Coccomorpha: Coccidae), with descriptions of eight new species, Zootaxa 5646 (2), pp. 151-198 : 184

Platylecanium riouwense Takahashi

Platylecanium riouwense Takahashi, 1951: 104 .

Platylecanium riouwanse Takahashi ; Joshi & Firake 2019: 7. Misspelling of species epithet.

Comments. Platylecanium riouwense , from the Riau (Riouw) Is in the Philippines, was only briefly described and illustrated by Takahashi (1951), who did not indicate the host. It does not appear to have been collected since. From the description, it seems extremely likely that the venter was missing as no details are given of ventral structures and only 1 incomplete specimen exists. The key character-states that can be gleaned from his description are: (i) body elongate, 2.6 mm long, about 2.2 times longer than broad; (ii) margin not crenulated (“simple”); (iii) dorsum with faint, large areolations submarginally; (iv) clear areas present, but perhaps only posterior 3 pairs; (v) stigmatic clefts small, each with 3 stigmatic spines; (vi) stigmatic spines slender and blunt, not reaching margin; (vii) marginal setae short, fine and curved, much shorter than stigmatic spines; (viii) marginal setae few, perhaps with only 6 on each side between stigmatic clefts; (ix) anal plates about 2.5 times longer than width of a single plate, each with a blunt apex, and (x) each anal plate with posterior margin convex and subequal in length or slightly shorter than anterior margin.

It is unfortunate that no characters on the venter were described by Takahashi. However, in having an elongate body, more than twice as long as wide, P. riouwense somewhat resembles P. asymmetricum , P. cyperi , P. dendrobii and P. palmae (the latter two species are described as new above). However, P. riouwense apparently differs from P. asymmetricum in having (i) a non-crenulate margin (the margin of P. asymmetricum is crenulated) and (ii) no cleft on on inner margin on underside of anal plate. Platylecanium riouwense differs from the other three species in having the anterior and posterior margins of the anal plates subequal in length or posterior margin shorter than the anterior margin, and each plate with a blunt apex (the other three species have anal plates with the posterior margins clearly longer than anterior margins, and each plate has a pointed apex). Platylecanium riouwense also differs from P. palmae in having few marginal setae (about 6) on each side between the stigmatic clefts (more than 20 on P. palmae ), and in having large areolations (small in P. palmae ). It also differs from P. dendrobii in having the body rounded at both ends (clearly not rounded on P. dendrobii ), and probably differs from P. cyperi in the arrangement of the dorsal areolations.