Eulacestoma, De Vis, 1894

Schoddei, Richard & Christidis, Les, 2014, Relicts from Tertiary Australasia: undescribed families and subfamilies of songbirds (Passeriformes) and their zoogeographic signal, Zootaxa 3786 (5), pp. 501-522 : 508-509

2. Eulacestoma

Because of its remarkable bilaterally compressed bill, New Guinean Eulacestoma was grouped traditionally with the Australasian shrike-tits ( Falcunculidae ) and whistlers ( Pachycephalidae ) ( Mayr 1941, 1967; Rand & Gilliard 1967; Beehler & Finch 1985; Beehler et al. 1986; Coates 1990; Sibley & Monroe 1990; Dickinson 2003; Boles 2007a). Multi-locus DNA sequence studies since have corroborated a sister relationship between the shrike-tits and whistlers ( Barker et al. 2004; Jønsson & Fjeldså 2006; Driskell et al. 2007; Norman et al. 2009b; Jønsson et al. 2011; Aggerbeck et al. 2014), but not with Eulacestoma . Norman et al. (l.c.) did recover exclusive links between them, but support was weak. Other studies ( Jønsson et al. 2007, 2011) found Eulacestoma sister instead to a large cluster of corvoid families that includes the crows ( Corvidae ), shrikes ( Laniidae ), birds-of-paradise ( Paradisaeidae ), fantails ( Rhipiduridae ), monarchs ( Monarchidae ) and, in the first study, whistlers. Since then, Aggerbeck et al. (2014), using sequences from 22 loci and with robust support, recovered Eulacestoma as sister to the Australo-Papuan sittellas ( Neosittidae ). These, in turn, were sister to a group of corvoid families that included the Old World orioles ( Oriolidae ), vireos ( Vireonidae ) and Australo-Papuan whipbirds ( Psophodidae ). Whatever the inter-familial relationships of Eulacestoma , they are clearly distant from other corvoid families.

Morphological traits support these findings. Although the bills of Eulacestoma and Falcunculus are similar in appearance, the structure of the temporal area of the skull, where jaw muscles attach, differs markedly. Unlike its form in Eulacestoma (see diagnosis), the temporal fossa is smaller, deeper and clearly defined in Falcunculus , with both postorbital and zygomatic processes short but clearly developed; the latter is distinctively thickened at the base. Thus the bills of the two genera are evidently used in different ways, and convergent in gross form. Moreover, the ectethmoids are short and narrow in Falcunculus , and its lachrymals appear to be free. Based on the combined molecular and morphological data now available, Eulacestoma is separated here in its own family.