Dusky Tetraka Crossleyia tenebrosa Scientific name definitions

14–15 cm; one unsexed 21.4 g. Small species, dark with yellow throat, robust legs, fairly short bill with lower mandible slightly inflated centrally and appearing somewhat upcurved distally. Plumage is dark dull olive-green above, tail and wings dark dull olive-brown, outer edges of flight-feathers dark green; supraloral area yellow, remainder of face side dark olive-green, conspicuous and contrasting yellow broken eyering; chin, throat and malar area yellow, breast, flanks and undertail-coverts dark olive-green, belly and vent yellow-green; iris mid-brown; bill dull pinkish-orange, dark culmen; legs pale fleshy pink. Differs from similar Spectacled Tetraka (Xanthomixis zosterops) in darker underparts contrasting more strongly with yellow throat, shorter tail, longer, stouter legs and feet. Sexes alike, female on average smaller than male. Juvenile undescribed.

Previously placed in Xanthomixis, where, on basis of similarities in plumage pattern, was thought to be most closely related to the Spectacled Tetraka (Xanthomixis zosterops). However, genetic analysis indicates that this species is actually sister to the Madagascar Yellowbrow (Crossleyia xanthophrys) (1 Block, N.L. (2012). Cryptic Diversity and Phylogeography in the Bernieridae, an Endemic Malagasy Passerine Radiation. PhD thesis, University of Chicago, Chicago. Close ), and so is moved to the genus Crossleyia (2 Clements, J. F., P. C. Rasmussen, T. S. Schulenberg, M. J. Iliff, T. A. Fredericks, J. A. Gerbracht, D. Lepage, A. Spencer, S. M. Billerman, B. L. Sullivan, M. Smith, and C. L. Wood (2024). The eBird/Clements Checklist of Birds of the World: v2024. Cornell Laboratory of Ornithology, Ithaca, NY, USA. Close ).

NE Madagascar, from at least Marojejy S to Zahamena. Few reliable records since 1930. Reports from Masoala Peninsula, Analamazaotra and Ranomafana National Park require confirmation (3 Safford, R.J. and Hawkins, A.F.A. eds. (2013). The Birds of Africa. Vol. 8. The Malagasy region. Christopher Helm, London. Close ).

Arthropods. Occurs in small groups; sometimes in mixed-species flocks. Largely terrestrial, foraging in areas of often sparse understorey and deep leaf litter; hops rapidly. Sometimes seen in low shrubs, to 0.5 m, particularly when calling. Report of a single individual at 2 m moving through tall branches and clinging to vertical stems seems exceptional, and possibly based upon a misidentification.

A series of quiet, high-pitched hissing and twittering calls, similar to those of other members of genus; single contact call a quiet tseip or tsit.

VULNERABLE. Restricted-range species: present in East Malagasy Wet Forests EBA. Global population estimated to number fewer than 10,000 individuals. Clearly rare and local, as numerous recent intensive surveys in many forests of E Madagascar, covering wide range of habitats and altitudes, have failed to locate it. Enigmatic; has been widely misidentified in the past, since key identification criteria only recently determined and still poorly understood. Only recent documented records are from Marojejy and Zahamena National Parks; reported also from Masaola, Perinet Special Reserve and Maroantsetra, but without details. Earlier specimen records from elsewhere, including the Andasibe-Mantadia region, but precise localities and altitudes are not known. Outside protected areas, main threats are from forest clearance for subsistence agriculture, which is most prevalent at altitudes at which present species is known to occur.