Microspizias, Sangster & Kirwan & Fuchs & Dickinson & Elliott & Gregory, 2021

Sangster, George, Kirwan, Guy M., Fuchs, Jerome, Dickinson, Edward C., Elliott, Andy & Gregory, Steven M. S., 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, pp. 419-424 : 419

Microspizias gen. nov.

Type species.

Falco superciliosus Linnaeus, 1766 (currently Accipiter superciliosus ).

Included species.

Microspizias superciliosus (Linnaeus, 1766), new combination, and M. collaris (P. L. Sclater, 1860), new combination.

Diagnosis.

Microspizias differs from all species of Accipiter by a combination of (i) small size (total length <30 cm), (ii) white vent barred grey (in adult M. collaris ) or chocolate-brown (in adult M. superciliosus ), and (iii) juveniles dimorphic, rufous morph with distinct rufous fringes to feathers of upperparts ( Ferguson-Lees and Christie 2001). In addition, Olson (2006) noted that in M. superciliosus the procoracoid process has a very distinct foramen. This foramen is invariably absent in Accipiter ( Olson 1987). Olson (2006) further pointed out that the configuration of the skull, sternum and pelvis of M. superciliosus are very different from Accipiter , and that the hind-limb bones of M. superciliosus are much more robust than the extremely gracile elements of Accipiter .

Microspizias differs from Kaupifalco monogrammicus by (i) absence of black and white throat stripes (black central throat stripe bordered on each side by a white stripe in Kaupifalco ), (ii) absence of a solid grey breast-band (present in Kaupifalco ), (iii) presence of three grey tail bands (one white band in Kaupifalco ), and (iv) yellow cere, tibia and toes (orange in Kaupifalco ) ( Ferguson-Lees and Christie 2001).

Microspizias differs from Melierax in (i) much smaller size (total length <30 cm; >42 cm in Melierax ), (ii) much shorter legs (tarsus <50 mm; >81 mm in Melierax ), and (iii) juveniles dimorphic, rufous morph with rufous feather fringes on upperparts (monomorphic, with brown upperparts in Melierax ) ( Ferguson-Lees and Christie 2001).

Microspizias differs from Micronisus gabar in (i) shorter tail (males <117 mm; >150 mm in Micronisus ), (ii) tail square-ended or notched (rounded in Micronisus ), (iii) yellow cere, tibia and toes (orange in adult Micronisus ), (iv) dark grey rump (white in Micronisus ), and (v) juveniles dimorphic, rufous morph with rufous feather fringes on upperparts (monomorphic, with brown upperparts in Micronisus ) ( Ferguson-Lees and Christie 2001).

Microspizias differs from Harpagus in (i) presence of three grey tail bands (two or three white or grey bands in Harpagus ), (ii) adult male without dark mesial throat stripe (present in Harpagus ), (iii) greyish-barred underparts (plain grey or rufous, or rufous-barred in adult Harpagus ), and (iv) juveniles dimorphic, rufous morph with rufous feather fringes on upperparts (monomorphic, with brown to black-brown upperparts in Harpagus ) ( Friedmann 1950; Ferguson-Lees and Christie 2001).

Microspizias differs from Urotriorchis macrourus in (i) much shorter tail (males <117 mm; >305 mm in Urotriorchis ), (ii) tail squared or notched (strongly graduated in Urotriorchis ), (iii) underparts with greyish bars (in M. collaris ) or chocolate-brown bars (in M. superciliosus ) (plain grey or rufous in Urotriorchis ), (iv) dark grey rump (white in Urotriorchis ), and (v) juveniles dimorphic, rufous morph with rufous feather fringes on upperparts (monomorphic, with black-brown upperparts in Urotriorchis ) ( Ferguson-Lees and Christie 2001).

Etymology.

The name is derived from the Greek words μικρος (small, tiny) and σπιζιας (hawk). Its gender is masculine. The name refers to the small size of both species, especially that of M. superciliosus .