Emerald Toucanet - Taxonomy

Taxonomy

It has been suggested that the Emerald Toucanet actually should be split into 7 species (below described as they roughly occur from north to south):

• Wagler's Toucanet (Aulacorhynchus wagleri). Endemic to south-western Mexico. Monotypic.
• Emerald Toucanet (Aulacorhynchus prasinus). Found from southern Mexico to Nicaragua. Includes subspecies warneri, virescens, stenorhabdus, chiapensis and volcanius.
• Blue-throated Toucanet (Aulacorhynchus caeruleogularis). Found in Costa Rica to western Panama. Incl. subspecies maxillaris.
• Violet-throated or Nelson's Toucanet (Aulacorhynchus cognatus). Found in eastern Panama and adjacent far north-western Colombia. Monotypic.
• Santa Marta Toucanet (Aulacorhynchus lautus). Endemic to the Santa Marta Mountains in northern Colombia. Monotypic.
• (North) Andean Toucanet (Aulacorhynchus albivitta). Found in the Andes from western Venezuela, through Colombia to northern Ecuador. Incl. subspecies griseigularis and phaeolaemus.
• Black-throated or Peruvian Toucanet (Aulacorhynchus atrogularis). Found from southern Ecuador, through Peru, far western Brazil (in the state of Acre), to central Bolivia. Incl. subspecies dimidiatus and cyanolaemus.

These splits are mainly based on morphology and plumage as described by Navarro et al. (2001). Their results were preliminary, as they themselves pointed out. As a result most authorities, notably SACC, do not recognize more than a single widespread species, but recognize the need for a solution to this complex. They are clearly separate species as per the phylogenetic species concept, but judging the species limits as per the biological species concept is difficult due to the entirely allopatric distributions of the various groups. There are no major vocal differences between the various populations, but that in itself is not unusual for separate species that do not overlap.

Genetic evidence has to some extent supported the above splits, although with different borders between the species in the northern Andes, and of the above suggested species, data is lacking for lautus. According to their genetic results, the north Ecuadorian toucanets, which are white-throated and usually included in albivitta, are closer to the atrogularis group than "true" albivitta of Colombia and Venezuela. Assuming this is correct, it seems likely that north Ecuadorian toucanets represent a new taxon, which should be treated as a subspecies of A. atrogularis. They also found that griseigularis was closer to the atrogularis group than albivitta, but unlike the north Ecuadorian toucanets, they opted for treating it as a separate species, the Grey-throated or Plumbeous-throated Toucanet (A. griseigularis). In that case, A. albivitta is known as the White-throated Toucanet. If albivitta and griseigularis are treated as separate species, it is unclear where phaeolaemus belongs, as genetic data for that taxon is missing. In appearance and distribution phaeolaemus is closest to griseigularis, but inexplicably it has been suggested it should be treated as a subspecies of A. albivitta. In 2011 it was also suggested that cyanolaemus should be treated as a subspecies of A. albivitta, but this was presumably an error, as it directly contradicts genetic data, which place it in A. atrogularis.

Another potential problem relates to the distribution limit between A. cognatus and A. caeruleogularis in Panama. Although the reason for this treatment is unclear, the population in central Panama has been placed in A. caeruleogularis, which would limit A. cognatus to extreme eastern Panama and adjacent Colombia. According to George Angehr, author of The Birds of Panama, it is possible toucanets from central Panama actually are closer to A. cognatus.