Megascops stangiae, Dantas & Weckstein & Bates & Oliveira & Catanach & Aleixo, 2021

Dantas, Sidnei M., Weckstein, Jason D., Bates, John, Oliveira, Joiciane N., Catanach, Therese A. & Aleixo, Alexandre, 2021, Multi-character taxonomic review, systematics, and biogeography of the Blackcapped / Tawny-bellied Screech Owl (Megascops atricapilla-M. watsonii) complex (Aves: Strigidae), Zootaxa 4949 (3), pp. 401-444 : 425-426

Megascops stangiae , sp. nov.

Xingu Screech-Owl

corujinha-do-xingu (Portuguese)

Otus watsonii usta ( Sclater, 1858) : Marks et al. (1999); Weick (2006; part: specimens between lower Tapajós and lower Tocantins rivers).

Megascops usta ( Sclater, 1858) : König et al. (1999); König & Weick (2008; part: specimens between lower Tapajós and lower Tocantins rivers).

Megascops watsonii usta ( Sclater, 1858) : Dickinson & Remsen (2013); Clements et al. (2019); Gill et al. (2020; part: specimens between lower Tapajós and lower Tocantins rivers).

Corresponding to Clade C recognized in this study, M. stangiae is endemic to Brazil and distributed along the lower parts of the Tapajos-Xingu and Xingu-Tocantins interfluves, and may not cross the Araguaia River . The southern limits of this taxon are unclear, but extend at least as far as the Serra dos Carajás (01º44’S, 51º27”W).

Holotype: MPEG 70627 Skin. A male collected on 4 August 2010 at Serra dos Carajás, Parauapebas , Pará State, Brazil (05º46’12.5”S; 50º29’54.9”W), and deposited at the Museu Paraense Emilio Goeldi.

Paratypes: MZUSP 93276 , unsexed, collected on 1 July 2010 at Porto de Moz , Pará, Brazil (2°10’57,04”S; 52°16’14,16”W) ; MZUSP 83558 , female, 110 g, collected on 12 December 2008 at Porto de Moz ; MPEG 53840 , female, smooth ovary 3x 1 mm, 125g, collected on 21 August 1997 at the Floresta Nacional do Tapajós , Belterra, Pará (3°05’43.96”S, 54°55’48.12”W) ; MPEG 70684 , male, testes 15x 10 mm, 130 g, brown iris, collected on 14 September 2010 at Floresta Nacional do Tapajós ; MPEG 70678 , male, testes 15x 10 mm, brown iris, 125 g, collected on 13 September 2010 at Floresta Nacional do Tapajós ; MZUSP 64307 , female, widest ovum 2 mm, 141 g, amber iris, collected on 26 September 1986 in the municipality of Altamira , Pará, Brazil (03°39’S, 52°22’ W) ; MPEG 65676 , male, testes 10x 5 mm, 130 g, brown iris, collected on 24 July 2008 at Floresta Nacional do Crepori , Jacareacanga, Pará, Brazil (6°34’45.67”S, 57° 9’4.91”W) ; and MPEG 70846 , male, brown iris, collected on 9 March 2010 in the district of Miritituba , Itaituba , Pará, on the right (east) bank of the Tapajós River (4°17’51.04”S; 55°57’19.63”W) .

Description of the holotype: A brown morph of the Megascops atricapilla-M. watsonii complex with Light brown upperparts (121D; Smithe 1975) and a Dark brown cap (219; Smithe 1975). Chest speckled with Dark brown (219) fishbone-shaped stripes in a light brown background, and belly Tawny-olive (223D; Smithe 1975) with a few dark brown fishbone-shaped stripes. Yellowish-brown underwing and tarsi coverts. Tail light Brown (119; Smithe 1975). Iris orange, bill lead-colored, tarsi whitish. Measurements: Wing length 168 mm; tail length 90.3 mm; tarsus length 29.1 mm; bill length at anterior end of nostrils 14.9 mm; bill width 8.5 mm; bill height 11.4 mm; body mass 140 g.

Variation in the type series: The type series is highly variable in overall color, as well as in the amount and shape of ventral stripes. It includes brown, red, and red-brown morphs, and some dark individuals are similar to dark morph Clade D birds (e.g. MPEG 70647 ; see below). Red morphs tend to have less stripes on underparts, and these may not look “fishbone-shaped”. Black on the crown can be reduced to spots or longitudinal stripes in red morphs .

Diagnosis: As Clade C birds, uniquely distinguished from all other lineages and taxa in the Megascops atricapilla-M. watsonii complex by six fixed (unvariable) synapomorphic (shared-derived) mutations (five transitions and one transversion) in sequences of the mitochondrial genes COI (positions 891, 948, 963, and 990 in the supplied alignment; Supplementary file 1) and cytb (positions 258 and 669 in the supplied alignment; Supplementary file 2). From a phenotypic perspective, no reliable morphological diagnosis exists with respect to other species in the complex, particularly among the Amazonian ones. Similarly, no single vocal character distinguishes M. stangiae from all other taxa in the Megascops atricapilla-M. watsonii complex, although pairwise diagnosability tests supported reciprocal vocal diagnoses with respect to most taxa, except clades D ( Megascops ater , see below) and E ( Megascops sp. nov., see below), as follows. Megascops stangiae is vocally distinguishable from M. atricapilla (Clade F, see below) and M. usta (Clade B, see below) by longsong pace (7.25±0.89 notes per second vs. 13.11±0.9 notes per second and 4.66±2.0 notes per second) and from M. watsonii (Clade A, see below) and M. atricapilla by shortsong pace (4.70±0.30 vs. 7.97±0.43 and 8.87±1.11 notes per second). No recording was obtained for the M. stangiae holotype, but longsong and shortsong recording from the same locality are available in xeno-canto under the numbers XC 22514 (longsong), obtained on 13 August 2008, and XC 26115 (shortsong), obtained on 30 November 2008, both by S.M. Dantas. Longsongs consist of monotonous sequences of equally spaced notes delivered during a variable period of time, gradually rising in volume until frequency stabilizes, becoming lower towards the end ( Fig. 8c ). Shortsongs are monotonous sequences of short notes, with upslurred (inverted U or V shaped) notes towards the end, with two parts, a slower-paced and a faster-paced that gradually slows down towards the end ( Figure 11c ).

Etymology: We name this species in honor of the late Sister Dorothy Mae Stang (1931‒2005), who had worked on behalf of poor farmers and the environment in the Brazilian Amazon region since the 1960s until she was brutally murdered by ranchers in Anapú, Pará State. The common names Xingu Screech Owl (English) and Corujinha do Xingu (Portuguese) refer to the area where the species is found, between the Tapajós and Xingu rivers, where Dorothy was very active as a community leader and ultimately was killed.

Habitat: The new species inhabits terra firme, igapó or várzea forests, from sea level to about 700 m (Serra dos Carajás). Apparently more common near the edge of the forest, and usually the most abundant nocturnal forest bird where it occurs. It perches from undergrowth to near canopy, and roosts by day inside holes or frequently inside bundles of dead leaves in the undergrowth (SMD, pers. obs.).

Remarks: Average uncorrected pairwise p-distances between M. stangiae and the remaining species in the Megascops atricapilla-M. watsonii complex were as follows: 6.4% ( M. watsonii ); 3.2 % ( M. usta ); 2.1% ( M. ater ); 2.3 % ( Megascops . sp. nov., see below); and 2.4% ( M. atricapilla ).

Figures

FIGURE 8. Examples of longsong audio spectrograms from clades A‒F of the Megascops atricapilla-M. watsonii complex. (A) Clade A: Venezuela, Rio Cuyuni (Paul Schwartz, ML 59376); (B1) Clade B: Peru, Madre de Dios (Ted Parker III, ML 11496 = locality B26 in Fig. 1); (B2) Clade B: Venezuela, Rio Cassiquiare (Paul Schwartz, ML 59397 = locality B23 in Fig. 1); (C) Clade C: Brazil, Serra dos Carajás (Sidnei Dantas, XC 22514); (D) Clade D: Brazil, IPEAN, Belém (Paul Schwartz, ML 59395); (E) Clade E: Brazil, Usina Serra Grande, Ibateguara, Alagoas (Curtis Marantz, ML 127980); (F) Clade F: Brazil, Caetetus Ecological Station, São Paulo (Alexandre Aleixo, ML 94909). Each sonogram is typical of a given clade, except for Clade B, where a slow-paced song (less than 4 notes/s), and a fast-paced song (more than 6 notes/s) are shown. The slow-paced individuals are all from the south bank of the Amazon River, while most of the fast-paced Clade B specimens come from north of the Amazon, except for some samples from the lower Inambari and Rondonia areas of endemism in Brazil (see Fig. 9).

FIGURE 11. Audiospectrograms of shortsongs of Megascops atricapilla-M. watsonii clades A, B, C, and F. (A) Clade A: Venezuela, Rio Grande (Paul Schwartz, ML 59359); (B) Clade B: Brazil, Mato Grosso (Curtis Marantz, ML 126830); (C) Clade C: Brazil, Serra dos Carajás (Curtis Marantz, ML 126657); and (D) Clade F: Brazil, Parque Estadual Intervales, São Paulo (Dan Lane, XC 75524).