At present, Bulbophyllum section Polymeres

comprises approximately 170 (provisionally) accepted species (232 names) according to Vermeulen et al. (2014), and with a few more recently described species added. Four informal series were proposed for this section in Schuiteman et al. (2010). These are useful for a first division in a key to the species of the section but are unlikely to reflect the phylogeny of this group as the resulting series are not supported by additional characters in, for instance, the flowers. A key to these series runs as follows:

1. Sepals (partly) connate series A

1a. Sepals free 2

2. Rhizomes creeping or straggling. Roots spreading, arising near most pseudobulbs including recently developed ones series B

2a. Rhizomes (shortly) ascending, patent to stiffly or limply pendulous. Roots usually growing towards the point of attachment of the plant over or alongside the rhizome. Recently developed shoots usually without roots 3

3. New shoots arising from a node along the rhizome (fig. 1a) or from the very base of the pseudobulb (fig. 1b), not perforating the pseudobulb above its base series C

3a. New shoots emerging above the node from which they originate, perforating the pseudobulb above its base (Fig. 1c, 1d, 1e) series D

In series D, the perforated part of the pseudobulb varies in length between species but varies little within species and is therefore of diagnostic value. In some species, the new shoots arise just above the base of the pseudobulb, in others close to the apex; compare Fig. 1c, 1d, and 1e.

While revising the New Guinea species of section Polymeres, we encountered several undescribed species. In this paper, we present the novelties in series B and C of the section.