Proposal (942) to South American Classification Committee

Transfer Accipiter superciliosus and A. collaris to the new genus Microspizias

Effects on South American CL: This proposal would transfer two Neotropical raptor species currently recognized under Accipiter genus, to the new genus Microspizias.

Background: Based on skeletal details, Olson (2006) proposed that the Tiny Hawk (Accipiter superciliosus) does not belong in genus Accipiter, and this was supported by genetic evidence (Kocum 2008). Olson (2006) recommended transferring Tiny Hawk to its own genus and suggested that Hieraspiza was available. However, the type species of that genus is A. virgatus (Dickinson & Remsen 2013), as designated by the author of the genus, Kaup (1845), prior to G. R. Gray’s subsequent (and therefore irrelevant) selection of “Falco tinus” (a synonym of A. superciliosus); thus, another valid genus name is required (Bierregaard & Kirwan 2020).

New information: Further genetic evidence (Hughall & Stuart-Fox 2012, Oatley et al. 2015, Mindell et al. 2018) supports the conclusions of Olson (2006) and Kocum (2008), which should also be applied to its sister taxa, the Semicollared Hawk (Accipiter collaris). Furthermore, new observations on nesting, showed that the Tiny Hawk prefers much more exposed sites to locate their nests compared to the typical Accipiters (Rivas-Fuenzalida & Angulo 2021). Recently, Sangster et al. (2021), proposed Microspizias as a new genus-group name for A. superciliosus and A. collaris.

Recommendation: Based on the osteological, genetic, and ecological evidence, following Sangster et al. (2021), I recommend transfer Accipiter superciliosus and Accipiter collaris to the genus Microspizias.

Literature Cited:

Bierregaard, RO and GM Kirwan (2020) Tiny Hawk (Accipiter superciliosus), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.

Dickinson, EC, and JV Remsen, Editors (2013) The Howard and Moore Complete Checklist of the Birds of the World. Fourth edition. Volume 1. Aves Press, Eastbourne, UK.

Hugall AF, and D Stuart-Fox (2012) Accelerated speciation in colour-polymorphic birds. Nature 485: 631–634.

Kaup, JJ (1845) Ueber Falken, mit besonderer Berücksichtigung der in Museum der Senckenbergischen naturforschenden Gesellschaft aufgestellten Arten. Museum Senckenbergianum 3: 229–262.

Kocum, A (2008) Phylogenie der Accipitriformes (Greifvögel) anhand verschiedener nuklearer und mitochondrialer DNA-Sequenzen. Vogelwarte 46: 141–143.

Mindell DP, J Fuchs, and JA Johnson (2018) Phylogeny, taxonomy, and geographic diversity of diurnal raptors: Falconiformes, Accipitriformes, and Cathartiformes. In: Sarasola JH, Grande J, Negro J (Eds) Birds of Prey. Springer, Cham, 3–32.

Oatley G, RE Simmons, and J Fuchs (2015) A molecular phylogeny of the harriers (Circus, Accipitridae) indicate [sic] the role of long distance dispersal and migration in diversification. Molecular Phylogenetics and Evolution 85: 150–160.

Olson, SL (2006). Reflections on the systematics of Accipiter and the genus for Falco superciliosus Linnaeus. Bull. Brit. Orn. Club 126(1): 69–70.

Rivas-Fuenzalida, T, and F Angulo (2022) Nesting records of the Tiny Hawk (Accipiter superciliosus) in eastern Peru. Ornitología Neotropical 33: 39–43.

Sangster, G, GM Kirwan, J Fuchs, EC Dickinson, A Elliott, and SMS Gregory (2021) A new genus for the Tiny Hawk Accipiter superciliosus and Semicollared Hawk A. collaris (Aves: Accipitridae), with comments on the generic name for the Crested Goshawk A. trivirgatus and Sulawesi Goshawk A. griseiceps. Vertebrate Zoology 71: 419–424.

Tomás Rivas-Fuenzalida, May 2022

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Comments from Remsen: “YES. Genetic data confirm the morphological data that suggested that these two species are not members of Accipiter, and I am assuming that the experts on nomenclature in Sangster et al. have correctly concluded that a new name is available. The proposed new name meets all Code qualifications.”

Comments from Areta: “YES. What a conundrum... I wish Hieraspiza was applicable to superciliosus, but Sangster et al. (2021) indicate it is not. Therefore, provided that their interpretations of The Code are correct (and they seem so to me), Microspizias must be adopted for superciliosus (and collaris).”

Comments from Lane: “YES, contingent on the fact that Microspizias is the correct name to apply to this new genus-level clade. However, I do wonder if Kaupifalco wouldn't be a reasonable genus to include these two in, considering it is the sister taxon to them? Yes, it's African, but the only substantive differences mentioned in the description of Microspizias are plumage or soft part coloration characters, not structural morphological characters. I'm sure raptorologists can provide a list of characters that make this grouping unnatural, but I am curious why that option wasn't discussed in Sangster et al 2021?”

Comments from Bonaccorso: “YES. It makes sense from the osteological and genetic evidence. On a related topic, with M. superciliosus and M. collaris so closely related to Kaupifalco monogrammicus (from Africa), one would think that they could be in the same genus (not so different, after all?). However, Mindell et al. (2018) said that this relationship “is not strongly supported and further data may be needed”. Also, biogeographically, it makes sense having them in separate genera. Finally, as I understand from Sangster et al. (2021), this is a new genus, which avoids any potential taxonomic conflict.”

Comments from Claramunt: “YES. A change required by phylogenetic evidence and nomenclatural reasons. The argument regarding the inapplicability of Hieraspiza or other existing names to superciliosus and collaris seems well researched and correct.”

Comments from Stiles: “YES. On genetic and nomenclatural grounds, this split and the new generic name are quite reasonable … and I like Elisa's comment regarding Kaupifalco as well.”

Comments from Robbins: “YES. Genetics and osteology demonstrate that it should not be in Accipiter.”

Comments from Pacheco: “YES. The allocation of this two-species clade to the newly described Microspizias based on osteological and genetic evidence closes the question.”

Comments from Jaramillo: “YES – multiple lines of evidence clarify that these two species are not Accipiters. The creation of Microspizias for the two is warranted.”