Proposal (1007) to South American Classification Committee

Transfer three species of Habia (H. gutturalis, H. cristata, and H. fuscicauda) to the new genus Driophlox

Background:

The genus Habia (commonly known as ant-tanagers) currently includes 5 species: H. rubica, H. gutturalis, H. atrimaxillaris, H. cristata, and H. fuscicauda. Three of these are part of the SACC checklist: Habia gutturalis, H. cristat, and H. fuscicauda. Genetic evidence has shown that the genus is not monophyletic. Using two mitochondrial DNA genes and four nuclear loci, Barker et al. (2015) showed that Habia rubica is sister to Chlorothraupis rather than to the other four species of Habia (Figure 1). Support for this relationship was strong: the posterior probability for the node uniting H. rubica with Chlorothraupis was 1.0, and the posterior probability for the node uniting all Habia excluding H. rubica was also 1.0. Although Habia was not monophyletic, all species of Chlorothraupis and Habia together form an exclusive clade. Based on these results, del Hoyo & Collar (2016) merged all species of Chlorothraupis into Habia, which has taxonomic priority over Chlorothraupis. This merger has not been followed by other classifications and checklists.

New Information:

A recent UCE study (Scott 2022) confirmed that Habia is not monophyletic, specifically that Habia rubica is phylogenetically distinct from the other four species (Figure 2). This study, encompassing phylogenetic analyses of 4,320 UCEs, used both concatenated maximum likelihood and multi-species coalescent (gene tree) approaches and showed that Habia is polyphyletic. Both analyses had strong support (100% bootstrap and 1.0 posterior probability) for the separation of H. rubica from the other species of Habia. Similar to Barker et al. (2015), Scott (2022) showed that H. rubica was sister to a clade containing species in Chlorothraupis. However, Scott (2022) also showed that the Habia rubica/Chlorothraupis clade was not the sister taxon to the clade containing the other four Habia.

The lack of monophyly of Habia necessitates a taxonomic change at the generic level. Because rubica is the type species of Habia, rubica must be included in the genus if the use of Habia is to continue. Therefore, Scott et al. (2024) made the following recommendations: 1) treat Habia as a monotypic genus, consisting of H. rubica, 2) continue to use Chlorothraupis for all species currently in Chlorothraupis, and 3) place the other four species currently in Habia in a separate genus. Because no genus name was available for these four species, the authors proposed a new genus, Driophlox.

Recommendation:

I recommend following the suggestions put forth in Scott et al. (2024). I do not recommend merging all Chlorothraupis and Habia species into Habia (as was done by del Hoyo and Collar (2016) for several reasons. First, the species of a combined genus consisting of Habia and Chlorothraupis are more disparate phenotypically than species in other genera of the Cardinalidae. Species of the sexually monomorphic Chlorothraupis have primarily olive plumage and lack the red plumage and crown patches/crests of the males of Habia. Species of Chlorothraupis also have proportionately shorter tails, <77% of wing length, versus ≥85% in Habia. Second, the node uniting the Habia-Chlorothraupis clade in Barker et al. (2015) is much deeper than the nodes uniting other cardinalid genera such as Cardinalis and Caryothraustes. Furthermore, the more recent study of Scott (2022) showed that the clade containing H. gutturalis, H. fuscicauda, H. cristata, and H. atrimaxillaris is more closely related to other cardinalids than it is to the clade consisting of Chlorothraupis and H. rubica. Therefore, using Habia for all species currently placed in Habia and Chlorothraupis does not reflect the phylogeny of the group. Another option would be to merge Habia rubica into Chlorothraupis. However, I do not recommend this option because of the phenotypic disparity between H. rubica and species of Chlorothraupis noted above. Therefore, I recommend transferring H. gutturalis, H. atrimaxillaris, H. cristata, and H. fuscicauda to Driophlox.

Figure 1. Phylogenetic tree (based on Barker et al. 2015). Maximum Clade Credibility tree indicating paraphyly of Habia, and deep-time split of Habia rubica and Chlorothraupis. Note that Barker et al. (2015) did not sample H. cristata.

Figure 2. Maximum Likelihood phylogeny based on ultra-conserved elements (UCE) illustrating the polyphyly of Habia (modified from Scott 2022). Branch lengths, shortened to aid in visualization, represent relative genetic divergence but are not time-calibrated. Collapsed clades are denoted by black triangles.

Literature Cited

Barker, F.K., Burns, K.J., Klicka, J., Lanyon, S.M. & Lovette, I.J. (2015) New insights into New World biogeography: An integrated view from the phylogeny of blackbirds, cardinals, sparrows, tanagers, warblers, and allies. The Auk: Ornithological Advances, 132(2), 333–348.

Scott, B. F. (2022) Phylogenetics of Cardinalidae and the Impact of Habitat, Climate, and Ecology on The Evolution of Color, Master’s Thesis, San Diego State University, San Diego, 155 pp.

Scott, B. F., Chesser, R. T., Unitt, P., and K. J. Burns (2024) Driophlox, a new genus of cardinalid (Aves: Passeriformes: Cardinalidae). Zootaxa 5406 (3): 497–500.

Kevin J. Burns, June 2024

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Comments from Remsen: “YES. Genetic data require a change to maintain monophyly, and especially with the new UCE data, and expanded Habia is untenable. The new name is feminine, like Habia, so no changes needed for variable endings. My only problem is that my brain cannot stop reading is as Dropbox.”

Comments from Areta: “YES. This was my WGAC vote: Scott et al (2024) discuss alternative generic treatments for the 5 species in Habia. The most convincing to me, when integrating external aspect, vocalizations, and genetic data is their preferred choice: Habia rubica, Chlorothraupis separate from Habia, and Driophlox fuscicauda, atrimaxillaris, gutturalis, and cristata. It seems that cristata was not sampled genetically, which is a pity giving its distinctive look and vocalizations. I have not tried to figure out where the samples of H. rubica came from to see if they included nominate rubica or not. Regardless, although it also seems that Habia rubica is in need of a taxonomic revision (Lavinia et al 2015), the constituent taxa are recovered as monophyletic in relation to gutturalis and fuscicauda.”

Comments from Robbins: “YES. The genetic data do dictate that a change be made and putting those four taxa into a new genus seems like the best course of action.”

Comments from Jaramillo: “YES – I like Kevin Burns’ summary of this problem. Three species into the new genus, Habia becomes a single species genus, and Chlorothraupis is retained. Looks like a fine resolution to this problem.”

Comments from Stiles: “YES. Habia as currently constituted is clearly paraphyletic, so splitting it to eliminate paraphyly clearly indicates retaining Habia with rubica, its type and only species, and naming a new genus for the remaining four ex-Habia species: the description of Driophlox is justified. Certainly these species do not belong with Chlorothraupis.”

Comments from Lane: “YES.”

Comments from Claramunt: “YES. The differences in the relationships among genera recovered by the two datasets is a bit disconcerting, but the non-monophyly of the traditional Habia seems well demonstrated.”