Proposal (687) to South American Classification Committee
Merge Pelecanoididae into Procellariidae
Effect on SACC: This would remove the family Pelecanoididae from our classification and place the genus Pelecanoides as Incertae Sedis within the Procellariidae.
Background: Our current footnote under Pelecanoididae is as follows:
1. The monophyly of the family, consisting of a single genus, has never been questioned. Livezey and Zusi (2007) treated them in their own suborder, as sister to all other Procellariiformes. However, genetic data (Nunn & Stanley 1998, Cracraft et al. 2004, Ericson et al. 2006) indicate that they may be embedded within the Procellariidae, as suggested by Cracraft (1981). Hackett et al. (2008) found a strongly supported sister relationship between the Pelecanoididae and Procellariidae, but with very limited taxon-sampling. SACC passed to change linear sequence of families. Christidis and Boles (2008) and Cracraft (2013) included them within the Procellariidae without even subfamily rank. Prum et al. (2015) found that Pelecanoides was embedded in the Procellariidae. SACC proposal badly needed.
As can be seen in proposal Pelecanoididae and Procellariidae, we’ve really just been waiting for sufficient genetic data to make this change. I that changed the linear sequence of families to reflect a close relationship between
New information: Prum et al. (2015) sampled 1 albatross (Phoebastria nigripes), 3 storm-petrels, 3 shearwaters (Fulmarus glacialoides, Puffinus griseus, Pterodroma externa) and 1 diving-petrel (Pelecanoides urinatrix), and found that the diving-petrel was sister to Pterodroma externa with strong support and was more closely related to that species than either was to Fulmarus glacialoides or Puffinus griseus. Here is a section of their Fig. 1:
Analysis and Recommendation: Of course better taxon-sampling will be needed to resolve the relationships of Pelecanoides within the Procellariidae, but it is clear that it is just a procellariid adapted for diving form the surface, and that over-emphasis on associated morphological adaptations has led to its placement as a separate family. As noted in the SACC footnote, two major sources have already eliminated family rank for Pelecanoides and placed it as just another genus within the Procellariidae. I strongly recommend following that treatment. I recommend placement of Pelecanoides at the end of the linear sequence of genera, Incertae Sedis, until additional analyses reveal its relationships within the family.
Van Remsen, October 2015
Comments from Stiles: “YES, a long-overdue change, as genetic data firmly place Pelecanoides in the Procellariidae.”
Comments from Jaramillo: “YES – although I am not happy about it. I liked the idea of the diving-petrels as this oddball and very different group of tubenoses being a family. However, when you see a very small shearwater, like Little Shearwater, the fact becomes clear that their very alcid-like look and flight style is more a function of small size and large body than anything all that unique about them. Small shearwaters essentially link the flight style and fast flapping style of the diving-petrels to larger and longer-winged tubenoses.”
Comments from Stotz: “YES Makes me sad, but not a surprising result.”
Comments from Zimmer: “YES. The genetic data are clear. Alvaro’s comments about the smallest shearwaters presenting a morphological bridge between diving-petrels and larger, longer-winged tubenoses are spot-on.”
Comments from Robbins: “YES. Genetic data clearly indicate that Pelecanoides is embedded within the Procellariidae.”
Comments from Pacheco: “YES. Pertinent proposal to further analysis that reveals their relationships within Procellariidae.”