Monographs Details: Retiniphyllum schomburgkii var. occidentale Steyerm.
Authority: Maguire, Bassett. 1965. The Botany of the Guayana Highland. Mem. New York Bot. Gard. 12 (3): 1-285.
Family:Rubiaceae
Description:Latin Diagnosis - A subsp. schomburgkii differt apice basique laminarum foliorum praesertim rotundatis vel obtusis, corollae lobis 11-14 mm longis, corollae tubo praesertim 8-8.5 mm longo, filamentis ad 9.5 mm longis.

Latin Diagnosis - A subsp. occidentale var. occidentale differt tubo calycis extus hirsutulo pilis patentibus onusto.

Discussion:The two subspecies of R. schomburgkii are mainly geographically separated to the east (Suriname, British Guiana, and Estado Bolivar, Venezuela) and west (Colombia boundary and Territorio Federal Amazonas, Venezuela), but intergrade and sometimes are found in the same locality, as on the summit of Cerro Duida. At the last locality are encountered collections of Maguire, Cowan & Wurdack 29810, referred to subsp. schomburgkii, with euneately acute to subacute leaf-base and subacute apex, and small corollas, and Maguire, Cowan & Wurdack 29704, referred to subsp. occidentale, with leaves more rounded at apex, rounded to subobtuse at base, and with longer corollas.