subsect. Bulaoanum Mayo,
Bot. J. Linn. Soc. 100: 168. 1989.
TYPE: P. bulaoanum Engl.
This subsection includes two species treated by Krause, P. bulaoanum and P. acuminatissimum. They probably represent the same species, a deeply 3-lobed plant with persistent, reddish brown cataphyll fibers. Currently the subsection is known only from South America. Krause treated this subsection as 'Gruppe' Doratophyllum, but that name cannot be used because it has no priority.
This subsection can be easily confused with and is perhaps inseparable from P. sect. Tritomophyllum. A moderately large number of South American species, including P. barrosoanum G.S. Bunting, P. cataniapoense G.S. Bunting (he places in P. "gruppe" Doratophyllum), P. effusilobum Croat, P. holtonianum Schott, P. hylaeae G.S. Bunting (P. sect. Calostigma), P. levelii G.S. Bunting (similar to P. barrosoanum), P. panduriforme Schott var. panduriforme, P. panduriforme var. reichenbachianum (Schott) Croat, and P. victoriae G.S. Bunting might all belong here.
The two groups are separated on weak features. Krause described his P. subsect. Bulaoanum (as "gruppe" Doratophyllum Engl.) as having somewhat succulent petioles which are longer than the blade; a hastate blade and ovaries which are several ovulate near the base of the locule whereas he describes P. sect. Tritomophyllum as having tripartite blades with the lateral lobes erect or spreading, and with the primary lateral lobes more prominent than the minor veins. The ovary is described as 5-11 locular with the locules 1 or more ovulate. The Central American species which appear to be closely related have one or two ovules per locule, whereas those of P. subsect. Bulaoanum are described as having several ovules per locule. These distinctions are pretty weak and further study of the members of both groups is necessary to decide if the two groups should be merged.