Commelina mathewsii (C.B.Clarke) Faden & D.R.Hunt

Commelina mathewsii (C.B.Clarke) Faden & D.R.Hunt (Faden & Hunt 1987: 122) . – Phaeosphaerion mathewsii C.B.Clarke (Clarke 1881: 138), as “Matthewsii”. – Athyrocarpus mathewsii (C.B.Clarke) Kuntze (Kuntze 1898: 319) .

Etymology

Named after the collector of the type specimen, British gardener Andrew Mathews.

Type material

PERU – Huánuco • Cassapi; 1840; fl.; A. Mathews 148; lectotype: K [K000363242]!, designated by Faden & Hunt (1987) .

Distribution

If distinct from C. robusta, then extending from northeastern Bolivia up to southeastern Peru, along the Andes.

Remarks

Commelina mathewsii has been a taxonomically dubious name since its description (Clarke 1881: 138). It was initially placed in the genus Phaeosphaerion despite the fact that the only known collection having only flowers and no fruits. Clarke based his decision on the flowers presenting “hastate-triangular” antherodes. The type specimen does seem morphologically similar to C. robusta due to gross morphology and C. rufipes due to its peculiar villose leaf-blade pubescence. Nonetheless, the label does not specify flower colour, nor does the specimen allow for that to be confirmed due to its poor preservation. Based on a handful of similar-looking specimens from Bolivia and Peru, it seems that leaf-blade pubescence is constant in these specimens, that flowers are blue and not white as in C. rufipes, and that fruits are dehiscent tan-coloured capsules. These characters, combined with leaf-blade pubescence and the antherode shape, would support C. mathewsii as a distinct species. Thus, C. mathewsii is most likely distinct but closely related to C. robusta . However, since we haven’t been able to study fresh specimens or herbarium ones with well-preserved flowers, we choose to retain this species as a dubious name instead of treating it as distinct or a synonym of C. robusta .