Rallus adolfocaesaris Alcover, Pieper, Pereira & Rando, 2015, n. sp.
Creators: name: Alcover, Josep Antoni
name: Pieper, Harald
name: Pereira, Fernando
name: Rando, Juan Carlos
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Aves
Gruiformes
Rallidae
Rallus
Rallus adolfocaesaris

description: Rallus adolfocaesaris
Rallus adolfocaesaris n. sp. forms with the rails from Pico, Graciosa, Terceira and Santa Maria, a Macaronesian group of species that share the display of legs less robust and wings less reduced than R. lowei n. sp. The humerus of R. adolfocaesaris n. sp. is slightly more gracile than in R. aquaticus, but considerably wider than in R. lowei n. sp.. Its size (c. 33 mm in length) is similar to that of the Pico rail, and much larger than the São Miguel rail (20%) and São Jorge (31%) rails. The smaller humerus in relation to R. aquaticus suggests a shortening of the primary remiges, although this reduction was probably not so extreme as in R. lowei n. sp.
The hindlimb bones are gracile compared to R. lowei n. sp., and short in relation to R. aquaticus. R. adolfocaesaris n. sp. has a femur close in length to those of R. lowei n. sp., and slightly longer than in the rails of São Miguel, Terceira and Pico, but shorter than in R. aquaticus (7%) and longer than in R. minutus n. sp. (28%, see Figure 15). Its tibiotarsus is slightly shorter than in R. lowei n. sp., R. carvaoensis n. sp. and R. montivagorum n. sp., shorter than in R. aquaticus (19%) and longer than in R. minutus n. sp. (11%, Table 1 & Figure 16). The ANOVA performed on the tibiotarsus distal width (trait 25) identified significant morphological differences (F4,84=8.872; p <0.001) between R. adolfocaesaris n. sp. and R. carvaoensis n. sp. (p = 0.007) and R. minutus n. sp. (p = 0.002) but not with R. montivagorum n. sp. (p = 0.262) and R. aquaticus (p = 0.504). R. adolfocaesaris n. sp. has a similar tarsometatarsus length (U = - 0.342; p = 0.833) but a smaller tarsometatarsus distal (U = -2.449; p = 0.012) and proximal width (U = - 2.646; p = 0.006) than R. lowei n. sp. The tarsometatarsus is shorter (20%) than in R. aquaticus (U = - 2.838; p <0.001), and longer (25%, U = -2.236; p = 0.0.36) than in R. minutus n. sp. No differences were detected in tarsometarsus proximal (U = - 1.492; p = 0.171) and distal widths (U = -1.167; p = 0.262) between R. adolfocaesaris n. sp. and R. minutus n. sp. Seemingly, the ANOVA did not detect any relevant difference in tarsometatarsus length, and proximal and distal widths between R. adolfocaesaris n. sp. and the rails of São Miguel and Pico.
The ratio of humerus-to-femur length ratio (0.85) suggests that R. adolfocaesaris n. sp. was a flightless bird. According to this figure, and since the hindlimb bones are thinner than in R. lowei n. sp., the loss of the flying capacity should have been less extreme in R. adolfocaesaris than in the Madeiran rail. The short stout tarsometatarsus (relative to the femur) suggests that R. adolfocaesaris n. sp. could be a slow-pace runner.
description: Published as part of Alcover, Josep Antoni, Pieper, Harald, Pereira, Fernando & Rando, Juan Carlos, 2015, Five new extinct species of rails (Aves: Gruiformes: Rallidae) from the Macaronesian Islands (North Atlantic Ocean), pp. 151-190 in Zootaxa 4057 (2) on page 180, DOI: 10.11646/zootaxa.4057.2.1, http://zenodo.org/record/233597