Integrative taxonomy reveals hidden diversity in the Catharus fuscater (Passeriformes: Turdidae) complex in Central and South America Author Halley, Maưhew R. Department of Biodiversity, Earth and Environmental Science, Drexel University, Philadelphia, Pennsylvania, USA, 19104 Author Catanach, Therese A. Ornithology Department, Academy of Natural Sciences of Drexel University, Philadelphia, Pennsylvania, USA, 19103 Author Klicka, John Burke Museum of Natural History and Culture, Department of Biology, University of Washington, Seaưle, Washington, USA, 98105 Author Weckstein, Jason D. Department of Biodiversity, Earth and Environmental Science, Drexel University, Philadelphia, Pennsylvania, USA, 19104 & Ornithology Department, Academy of Natural Sciences of Drexel University, Philadelphia, Pennsylvania, USA, 19103 text Zoological Journal of the Linnean Society 2023 2023-07-07 199 1 228 262 http://dx.doi.org/10.1093/zoolinnean/zlad031 journal article 266146 10.1093/zoolinnean/zlad031 b9190aec-ed9f-4c04-8914-daa1913ef189 0024-4082 8326302 Catharus mentalis Sclater and Salvin 1879 Cochabamba nightingale-thrush ( Figs. 15 , 16 ) Catharus mentalis Sclater and Salvin 1876: 352, 1879: 591 ; Seebohm 1881: 285; Sharpe 1902: 182; Warren and Harrison 1971: 346. Catharus fuscater mentalis Berlepsch 1902 , Hellmayr 1934: 467 ; Bond and Meyer de Schauensee 1942 , Bond 1956: 242 ; Ridgley and Tudor 1989: 109; Fjeldså and Krabbe 1990: 554 ; Clement 2000: 299 ; Collar 2005: 700 (in part); Halley 2020 , Halley 2021 . Catharus fuscater Meyer de Schauensee 1966: 412 (in part); Meyer de Schauensee 1970: 342 (in part); Schulenberg et al. 2007(in part); Vidoz 2009, Remsen et al. 2023 (in part). Type material Monotypic species. NHMUK 1885.3 .2.35 ( syntype ), study skin, from the Salvin–Godman Collection, collected by C. Buckley at ‘Suape’ in ‘prov. Yungas, Bolivia’ (= Suapi , La Paz , approximately –15.30˚, –67.31˚; see: Paynter 1992: 141), in 1876 ( Warren and Harrison 1971: 346) ; NHMUK 1885.3 .2.36 ( syntype ), collected by C. Buckley in ‘Yungas’ (presumably at Suapi , La Paz ) in 1876 ; NHMUK 1886.8 .2.20 ( syntype ), collected by C. Buckley at ‘Suapi’, Bolivia . These specimens were not examined in this study. Label data were provided by A.L. Bond ( in litt. ) . Geographic range Occurs in southern Peru , east of the Río Apurímac , east to Santa Cruz , Bolivia (Vidoz 2009). Adult specimens examined Bolivia ( N = 12): La Paz ( five males , three females ): Laguna Zongo : DMNH 67204 , 67207 (males), DMNH 67201 , 67206 (females); unspecified locality on the Río Aceramarca : AMNH 229261 (male); Sandillani: AMNH 138743 (male); Nequejahuruira: AMNH 229258 (male), AMNH 229257 (female) ; Cochabamba ( two males , one female ): Cerro Incachaca : CM 120346 , FMNH 181675 (males), CM 120345 (female) . Peru ( N = 9): Cusco ( five males , two females ): La Esperanza , Paucartambo : FMNH 433742 , 433738 (males), FMNH 433740 (female); Pillahuatta , Puacartambo : FMNH 430057 (male); Bosque San Luis : FMNH 299706 (female); Limacpunco : FMNH 222381 (male) ; San Pedro Village : FMNH 364458 (male); Puno ( one male ): Oconeque : ANSP 102367 (male) . Immature specimens examined Bolivia ( N = 6): La Paz ( five males , two females ): Laguna Zongo: DMNH 67200 , 67202 , 67203 , 67205 (males), DMNH 67198 , 67199 (females); Acara: AMNH 229260 (male) . Peru ( N = 3): Cusco ( one male , two females ): Occobauiba Valley , Tocopoquen : USNM 273314 (female); Bosque San Luis: FMNH 299705 (male); Pensión Suecia , km 138.5 on Cusco-Shintuya Highway , Cosnipata Valley : FMNH 398318 (female) . Audio recordings examined Bolivia ( N = 3): La Paz : Fuertecillo: XC 123041; Río Milluni near Titi Amaya, Inquisivi: XC 1998; Muñamachay: XC 73252. Peru ( N = 4): Junín : Cordillera Vilcabamba , headwaters of Río Poyeni : ML 92162 ; Puno : Sina: ML 148105, 148129, 148130. Diagnosis Genetics: In the UCE tree, samples of C. mentalis formed a clade that was sister to a large South American clade composed of samples of C. o. opertaneus , C. o. tenebris ssp. nov., C. b. berlepschi , and C. b. nebulus ssp. nov.. In the ND2 tree, samples of C. mentalis also formed a clade, but its placement in the broader phylogeny of the complex was unresolved. The divergence of C. mentalis from C. f. fuscater was estimated at 2.4 Mya (95% HPD = 1.9–3.0), and C. mentalis was also highly divergent from C. b. nebulus ssp. nov., its northern geographic neighbour and the only population likely to establish secondary contact with it during glacial maxima (mean uncorrected p -distance = 0.07 ± <0.01). ABGD and ASAP analyses both identified C. mentalis as an independent genetic cluster. Morphology: Specimens of C. mentalis exhibited polychromatic plumage colour, with two distinct colour phenotypes in males, unlike other taxa in the complex ( Fig. 8 ), except possibly C. f. fuscater and C. b. nebulus ssp. nov. (see above). Male specimens were clearly separable into ‘grey’ ( FMNH 222381, FMNH 430057) and ‘brown’ ( ANSP 102367, FMNH 181675, FMNH 299705, FMNH 364458) phenotypes. ‘Grey’ males were similar to C. f. sanctaemartae males, but with slightly browner (and less dark) breasts and throats and reduced black on the chin. ‘Brown’ males resembled C. mentalis females in plumage colour, and in having a black maxilla (a retained juvenile character).Females of C. mentalis were similar in colour to C. f. fuscater females ( Tables 3 , 4 ). Voice: Catharus mentalis was distinguished from all taxa except C. o. tenebris ssp. nov., C. o. opertaneus , and C. b. nebulus ssp. nov., by its Type 3 (‘short/simple’) punctuation call structure. Its ‘ascending’ blurred call was of higher frequency, simpler in structure, and shorter in duration than the ‘check-shaped’ blurred calls of C. b. nebulus ssp. nov. and C. b. berlepschi ( Fig. 11 ). Among these taxa, the punctuation calls of C. mentalis were the simplest in structure ( Fig. 9 ). No tetradic song contours were detected in C. mentalis ( Fig. 12 ). Our classification system for song contours was unable to score a remarkably slow-paced song ( BAC ) followed by a rapid trill ( XC 123041) and a six-note contour that featured a typical BA contour followed by an extremely rapid CDAB contour ( XC 1998). Although our sample of recordings is small, these two songs were unique in our dataset, suggesting that C. mentalis is vocally divergent from the rest of the complex. Of the three triadic contours ( ACB , BAC , CBA ) detected in C. mentalis , two ( ACB , BAC ) were detected in its northern neighbour ( C. b. nebulus ssp. nov.). Comments To our knowledge, the plumage polychromatism of C. mentalis is novel in the C. fuscater complex (except possibly in C. f. [ fuscater ] and C. b. nebulus ssp. nov., see above) and unprecedented in the genus Catharus . This pattern is illustrated by two specimens with enlarged testes ( FMNH 433738, 433742), collected at the same site in November 2001 , a ‘mossy forest’ at La Esperanza ( 2800 m . elevation), north-east of Paucartambo, Cusco , Peru ( Fig. 8 ).