P. ser. Ovata, ser. nov.
TYPE: P. smithii Engl.
Caudex longus vel brevis; internodia plerumque longior quam lata; cataphylla plerumque decidua; petiolus subequans laminum, teres vel subteres, cum annulo deficienti apice; lamina ovata vel ovato-triangulata, cordata vel sagittata ad basi; pistilla cum stylo plerumque "type B", rare C; ovaria 4-8 locularia; locula uniovulata aut raro 2-3.
Philodendron ser. Ovata is a somewhat heterogenous group characterized by having blades ovate to ovate-triangular, cordate to subcordate at base with terete or subterete petioles which lack an annular ring at apex. Locules vary from 4-8 and each usually has a single ovule per locule. Though there are only Central American species known, the series undoubtedly has South American representatives.
The relationship with other members of P. subsect. Belolonchium is uncertain. Aside from the usually solitary ovule per locule and usually somewhat spongy petiole, there is little resemblance between this group and typical members of P. subsect. Belolonchium which have elongated rather than more or less ovate blades. Philodendron dominicalense is the most doubtful member of the group. With the strongest possible similarity to P. dodsonii except for having a solitary ovule per locule, rather than about 20 ovules per locule as in P. dodsonii, it would appear that it might belong elsewhere. Philodendron cotonense, despite having 4-5 ovules per locule may belong in this section, considering its marked resemblance to P. wilburii and even P. smithii.
Central American species of P. ser. Ovata are: P. dominicalense, P. microstictum, P. smithii, P. straminicaule, P. sulcicaule, and P. wilburii. With the exception of P. smithii which ranges from Mexico to Nicaragua, P. ser. Ovata in Central America primarily ranges from Nicaragua to Panama.