Otus frutuosoi, Rando, Juan Carlos, Alcover, Josep Antoni, Olson, Storrs L. & Pieper, Harald, 2013

Rando, Juan Carlos, Alcover, Josep Antoni, Olson, Storrs L. & Pieper, Harald, 2013, A new species of extinct scops owl (Aves: Strigiformes: Strigidae: Otus) from São Miguel Island (Azores Archipelago, North Atlantic Ocean), Zootaxa 3647 (2), pp. 343-357: 346-353

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Otus frutuosoi

new species

Otus frutuosoi   , new species

( Figures 2 View FIGURE 2 & 3 View FIGURE 3 )

Holotype: MCMa 1779.012, complete right tarsometatarsus.

Type locality: Gruta de Água de Pau (São Miguel Island, Azores Archipelago). All the material was collected on 28.VIII. 2011 by J.C.R and J.A.A.

Horizon: Holocene. 1970 ± 40 BP (49 cal BC – 125 cal AD) is the 14 C age of the dated sample (lab code: KIA – 47427).

Status: Extinct.

Etymology: The species name honours Gaspar Frutuoso (b. 1522 Ponta Delgada –d. 1591 Ribeira Grande), an early historian and chronicler of Macaronesia, who in the last years of his life wrote the huge work As Sáudades da Terra, in six volumes (not published until 1867). He is considered to be the first great historian of the Portuguese Atlantic islands. Frutuoso provided detailed ornithological information, including a list of the birds of São Miguel (Knecht & Scheer 1972).

Paratypes: MCMa 1780.02, complete left tarsometatarsus, proximal part slightly encrusted; IMEDEA 94638, nearly complete right tarsometatarsus, with the trochlea metatarsi II broken; MCMa 1781.012, complete right femur; MCMa 1782.012, complete right femur; MCMa 1783.012, complete left femur; DZUL 3057, left femur broken at the shaft, glued; MCMa 1784.012, left tibiotarsus, distal part slightly broken; MCMa 1785.012, right tibiotarsus, distal part slightly broken; MCMa 1786.012, nearly complete left tibiotarsus, with the condylus lateralis slightly eroded; MCMa 1787.012, complete right humerus, slightly encrusted; MCMa 1788.012, complete left humerus, slightly encrusted; MCMa 1789.012, nearly complete left humerus, slightly encrusted, with some damage to the deltoid crest; MCMa 1790.012, complete left humerus, slightly encrusted; MCMa 1791.012, complete right ulna; MCMa 1792.012, complete left ulna; IMEDEA 94639, complete left ulna, slightly encrusted; MCMa 1793.012, complete left ulna; MCMa 1794.012, proximal two thirds of left radius with the arcus origo musculi extensor longus digiti majoris broken; MCMa 1795.012, complete right coracoid; MCMa 1796.012, complete right carpometacarpus; MCMa 1797.012, complete right carpometacarpus; MCMa 1798.012, complete left carpometacarpus; DZUL 3058, complete left carpometacarpus; MCMa 1799.012; nearly complete ossa cinguli membri pelvis (synsacrum + pelvis), with both scapus pubis broken; MCMa 1800.012, damaged associated skeleton, partially encrusted, including premaxilla, skull fragments, jaw fragments, a nearly complete right humerus, slightly broken at its distal end, two distal ends of ulnae, two fragmented radii, two scapulae, a fragmented right coracoid, two complete femora, two proximal ends of tibiotarsi, a fragmented right tarsometatarsus, some fragments of pelvis, three vertebrae, and some ribs.

Other material belonging to O. frutuosoi:   Five fragmentary bones (three femora, one tibiotarsus, one humerus), used to obtain a 14 C AMS date.

Suggested English name: São Miguel Scops   Owl.

Diagnosis: A small species of Otus   with forelimb elements (humerus, ulna and carpometacarpus) shorter than those of O. scops   , but with the femur, tibiotarsus and especially tarsometatarsus longer. The pelvis is shorter and broader than in Otus scops   . The premaxilla is less robust than in Otus scops   , with its tip less directed downward than in that species, giving a less pointed appearance in lateral view ( Figure 2 View FIGURE 2 ). The new species differs from the extinct O. mauli   in the significantly smaller size of all its bones (excepting the scapula and tarsometatarsus), especially the ulna and tibiotarsus (Table 1; Figures 3 View FIGURE 3 & 4 View FIGURE 4 ).

Remarks: The new species is most similar to O. scops   and O. mauli   in its overall morphology. The tarsometatarsus of the new species is similar in size to that of O. mauli   (U = - 1.1; p = 0.4) but is more robust ( Figure 3 View FIGURE 3 ). The femur is likewise similar (31.0 vs. 33.2 mm), but O. frutuosoi   has a shorter ulna (43.6 mm) and tibiotarsus (49.5 mm) than O. mauli   (c. 51.0 and 55.0 mm respectively), differences of 14.5 % and 10 % (Table 1 and Figures 3 View FIGURE 3 & 4 View FIGURE 4 ).

The MANOVA performed with the total lengths of humerus, ulna, carpometacarpus, and femur identified significant morphological differences between O. frutuosoi   and O. scops   (Wilks’ lambda = 0.0017, d.f. = 4, 24; p<0.001). The new bird has a shorter humerus (F1,29 = 36.55; p<0.001), ulna (F1,29 = 90.3; p<0.001) and carpometacarpus (F1,29 = 129.06; p<0.001) than O. scops   , but a longer femur (F1,29 = 11; p= 0.003). In addition, the new species has a longer tarsometatarsus (U = - 2.78; p<0.005) and tibiotarsus (U= - 2.55; p= 0.005) (Table 1; Figures 3 View FIGURE 3 & 4 View FIGURE 4 ).

The percent difference is not the same for each bone and the differences are larger for distal ends of wing and leg (Table 1). The total length of the wing bones (humerus + ulna + carpometacarpus) is 14 % smaller in the new species than in O. scops   , while the total leg length (femur + tibiotarsus + tarsometatarsus) is 11.6 % greater in O. frutuosoi   than in O. scops   .

The estimated weight of O. frutuosoi   , 144 ± 35 g (128.6–151.6) (n = 5), is on average 34.6 % higher than the weight of O. scops   obtained by the same method, 107 ± 10 g (82–130) (n = 25).

The average wing area of O. scops   is 170 ± 13 cm 2 (n= 6), whereas the estimated maximum wing surface in O. frutuosoi   (114 cm 2) is 33 % smaller ( Figure 5 View FIGURE 5 ). Our approach assumes that the flight feathers of O. frutuosoi   were reduced to the same proportion as the bones ( Figure 5 View FIGURE 5 ), although they may have been reduced even further.

The area of the spread wing directly contributed by the humerus is smaller than that contributed by the ulna and carpometacarpus (see Figure 5 View FIGURE 5 ). The reduction of wing surface of O. frutuosoi   in comparison with O. scops   is mostly a factor of reduction in the distal wing elements, which are more shortened in O. frutuosoi   than the proximal ones. Such a differential reduction has been observed in other flightless birds, in which the shortening of the manus precedes the reduction in other wing elements (Nudds & Davidson 2010). Because the surface reduces as the square of linear dimensions, the reduction of the whole wing surface in O. frutuosoi   in relation to O. scops   may have been greater than 33 %.

The ratio of body weight to wing area (using the mean values) indicates a wing loading of 0.31 g /cm - 2 for O. scops   but this is estimated to have been nearly 100 % greater in O. frutuosoi   (0.63 g /cm - 2). This is likely an overestimate because of probable reduction in relative weight, compared to femur length, of flight musculature in O. frutuosoi   . The ratio of combined humerus, ulna and carpometacarpus lengths to femur length is smaller in O. frutuosoi   (3.30: 1) than for O. scops   (4.07: 1) (data from Table 1), suggesting weaker powers of flight. Overall, these results strongly suggest that O. frutuosoi   had ground –dwelling habits.

The PCA performed with the proportions of hind- and forelimb bones (Table 2; Figure 6 View FIGURE 6 ) produced two principal components explaining 72.1 % of the total variance. 43.9 % is explained by PC 1, which shows a high positive weighting for ulna and femur lengths, and a high negative weighting for tarsometatarsus and carpometacarpus. PC 2 explained 28.2 % of the variance and shows a high positive weighting for humerus length, and a high negative weighting for carpometacarpus and ulna.