Syntype. Merida, Venezuela, Moritz 839 in part (K); Linden 350.
The Linden 350 specimen, a syntype, was first cited by Schumann [Mart. Fl. Bras. 6(6): 179. 1889] under M. meridensis, but later was included by Wernham in his description of M. sonderiana. Standley, however, failed to note this transference and cited the Linden 350 collection under both M. meridensis and M. sonderiana.
Although Wernham describes the corolla tube as “extus glaberrimo,” the presence of indument is obvious on the Kew specimen of Moritz 839 and partakes of a loose puberulous type varying from sparse to moderate. On the Linden 350 specimen the pubescence is likewise present on the exterior of the corolla, although the corolla is not mature. On both the Moritz 839 and Linden 350 specimens the calyx lobes are elongated, varying from 2.5-3 mm long in anthesis with an abundance of subappressed hairs on the inner surface, but glabrate on the outer surface with ciliolate margins. Wernham does not mention the pubescence on the interior surface of the calyx lobes, but this character is found on all the specimens of the syntypes, as well as on the Breteler 4539 specimen. In this respect, M. sonderiana differs from M. tachirensis Steyerm. and M. tamaensis Steyerm., both of which have the calyx lobes glabrous within.
The leaves are described by Wernham as “utrinque demum glabra,” but my examination of the syntype specimens shows the lower midrib and lateral nerves of the leaf blades to be pilose with appressed spreading hairs but the surface itself glabrous.
An emended description of M. sonderiana to include the above discrepancies is here given. Foliorum laminae subtus costa media nervis lateralibus pilis adpressis pubes-centae; hypanthio puberulo vel lanuloso; corollae tubo extus villosulo, lobis extus villosulis intus glabris.