Milvago diazfrancoi, Suárez, 2020

Suárez, William, 2020, The fossil avifauna of the tar seeps Las Breas de San Felipe, Matanzas, Cuba, Zootaxa 4780 (1), pp. 1-53 : 36-37

† Milvago diazfrancoi sp. nov.

Díaz Franco’s Caracara ; Caraira de Díaz Franco

(Figure 14: A–G; Table 9)

Holotype. Right tarsometatarsus without trochleae metatarsorum II and IV, MNHNCu 75.4610. Collected in San Felipe I, on May 14, 2009, by William Suárez and Stephen Díaz Franco.

Measurements (mm) of holotype. Total length: 57.2; proximal width: 8.4; width of shaft at midpoint of tubercle for tibialis anticus: 6.9; least width of shaft: 3.1; width of trochlea metatarsi III: 2.9.

Diagnosis. The smallest or most delicate species in Milvago , with tarsometatarsus slightly more slender than in M. brodkorbi Campbell, 1979 .

Etymology. Species dedicated to my colleague and friend Stephen Díaz Franco, specialist in Antillean fossil mammals and companion in all my expeditions to Las Breas de San Felipe, where together we collected most of the material treated here.

Paratypes (topotypes). San Felipe I: distal third of left tibiotarsus, MNHNCu 75.7021; distal half of right tarsometatarsus, MNHNCu 75.7022; distal end of right tarsometatarsus, MNHNCu 75.4826; proximal half of right tarsometatarsus, MNHNCu 75.4825; distal half of left tarsometatarsus, MNHNCu 75.7023; distal end of left tarsometatarsus, MNHNCu 75.4824.

Description. This taxon is referable to the genus Milvago and not to Caracara , Daptrius Vieillot , Ibycter Vieillot , or Phalcoboenus d’Orbigny , by having (see Campbell 1979:94; Suárez & Olson 2003c:302) tarsometatarsus with short inner calcaneal ridge, outer calcaneal ridge with proximal orientation, shaft with prominent edges on both sides of the anterior metatarsal groove, trochleae bilaterally compressed, and trochlea metatarsi II broad at base. The tibiotarsus and tarsometatarsus (Fig. 14A–G) are considerably smaller than those present in Milvago carbo (see Suárez & Olson 2003c: fig. 1; table 1). Differs from M. chimachima Vieillot, 1816 ; M. alexandri , and M. brodkorbi , due to their smaller size ( Table 9). The tarsometatarsus has an elongated shaft (shorter in M. chimachima , M. alexandri , and M. brodkorbi ; slightly more longer in M. carbo ), compressed bilaterally more abruptly at the distal level of the tubercle for the tibialis anticus (less compressed in M. chimachima , M. alexandri , M. brodkorbi , or M. carbo ); the fossa supratrochlearis plantaris is expanded or large (smaller in M. chimachima , M. alexandri , M. brodkorbi , or M. carbo ).

Comments. This is the second Cuban species, the third for the West Indies, and the fourth in America, described as extinct for the genus Milvago . The latter genus was initially reported for Cuba by Acevedo-González & Arredondo (1982:64, table 1), after an error of identification (Oscar Arredondo, pers. comm. 1997). The subsequent deletion of this taxon from the catalog of Cuban fossil birds (cf. Arredondo 1984) was not commented on. Subsequently, a proximal fragment of a tarsometatarsus (WS 977), from Cueva de Paredones, province of La Habana (now Artemisa), was registered by Suárez & Arredondo (1997:101) as Milvago sp. This constitutes the first valid record of the genus for Cuba. This fossil is not referable to M. diazfrancoi sp. nov., or M. carbo (see Suárez & Olson 2003c), and so the taxon that it represents is totally unknown until now in Las Breas de San Felipe (contra Orihuela 2019:61). Therefore, the alleged synonymy considered by Orihuela (2019:61), of the specimen WS 977 and the Milvago material recovered in these tar seeps is erroneous and unfounded. The species most biogeographically related to M. diazfrancoi sp. nov. is M. alexandri from Hispaniola, which seems to derive from M. chimachima (see Olson 1976), a taxon known from fossils (Pleistocene) in Florida (= Falco readei Brodkorb, 1959a ; see Campbell 1980; Emslie 1998). Both have a much shorter tarsometatarsus compared with the species described here, in which this element resembles that of M. brodkorbi , but is more slender. Phalcoboenus chimango ( Vieillot, 1816) has been traditionally placed in the genus Milvago (see Fuchs et al. 2012) and well compared with the known fossil species. Its tarsometatarsus is slightly even more slender than in M. diazfrancoi sp. nov. and about the same size ( Table 9). Given the distribution of P. chimango ( Canevari et al. 1991; White et al. 1994), and its generic position, it seems that all Antillean taxa are related in origins with M. chimachima , evolving with a more elongated tarsometatarsus than in the former, and more adapted to terrestrial locomotion, as in the case of P. chimango (see Mosto et al. 2013), under insular conditions and in sympatry with other endemic caracaras.

FIGURE 14. Milvago diazfrancoi sp. nov.: Right tarsometatarsus (Holotype, MNHNCu 75.4610) in anterior (A) and posterior (B) views; right tarsometatarsus (Paratype, MNHNCu 75.4825) in anterior view (C); left tarsometatarsus (Paratype, MNHNCu 75.7023) in posterior (D), and anterior (E) views; left tibiotarsus (Paratype, MNHNCu 75.7021) in distal (F) and anterior (G) views. Scale = 2 cm.