PS 44-91 - Placobdella akahkway n. sp. (Annelida: Clitellata: Hirudinea), a new leech species from central Canada

Background/Question/Methods

Members of the genus Placobdella (Annelida: Clitellata: Glossiphoniiformes: Glossiphoniidae) are sanguivorous, feeding mainly on amphibian and reptile blood, but some species are also known to feed on fish, and mammals (e.g. Sawyer, 1986; Siddall & Gaffney, 2004; de Carle et al. 2017). Species of Placobdella are distributed broadly throughout North America, with a few records of species invading Central America (Oceguera-Figueroa & Pacheco-Chaves, 2012; Kvist et al., 2018). The genus currently encompasses 24 nominal taxa, although this is likely an underestimate of the true species diversity within the genus. Using publicly available sequence data, and adding both mitochondrial and nuclear sequence data, de Carle et al. (2017) performed a comprehensive phylogenetic analysis of Placobdella, including all but one of the recognized species. Beyond evincing the general evolutionary histories of the species, the study also provided evidence of undescribed diversity; four species that neither conformed to known species descriptions, nor nested within clades of well-circumscribed species, were detected. Among which, Placobdella sp. 1 was phylogenetically separate from other species. We formally describe this new species based on morphological and phylogenetic investigations, and add additional genetic data for some newly sequenced specimens.

Results/Conclusions

We name this species Placobdella akahkway after the Plains Cree word for “leech,” in honour of the Indigenous language group spoken at this species’ collection sites (including the type locality) in eastern Alberta and western Saskatchewan. COI trees show that the included specimens of Placobdella akahkway form a monophyletic group with high support (parsimony bootstrap support [PBS] = 100%; maximum likelihood bootstrap support [LBS] = 100%). This clade places as the sister taxon to Placobdella kwetlumye (PBS = 87%; LBS = 97%). In turn, P. akahkway + P. kwetlumye place as the sister group to Placobdella burresonae (Siddall & Bowerman, 2006) but with somewhat weaker support (PBS = 50%; LBS = 98%). P. akahkway is a relatively large species (body length range 1.0-5.5cm), with variable, buff-brown external morphologies without patterning or pigmentation, and a mid-dorsal stripe. This species can be distinguished from all of its congeners on the basis of its possession of both compact and diffuse salivary tissues. Moreover, the large size of this species, the dorsal pigmentation in combination with the papillation pattern, and its geographic distribution might all lend themselves well to separating this species from other members of the genus.