Ibis (2013), doi: 10.1111/ibi.12041 A reappraisal of the systematic affinities of Socotran, Arabian and East African scops owls (Otus, Strigidae) using a combination of molecular, biometric and acoustic data ^ JEAN-MARC PONS,1,2* GUY M. KIRWAN,3 RICHARD F. PORTER4 &JER OME FUCHS5 1UMR7205 ‘Origine, Structure et Evolution de la Biodiversite’,Departement Systematique et Evolution, Museum National d’Histoire, Naturelle, 55 Rue Buffon, Paris, 75005, France 2Service de Systematique Moleculaire, UMS 2700, Museum National d’Histoire Naturelle, 43 rue Cuvier, Paris, 75005, France 3Field Museum of Natural History, 1400 South Lakeshore Drive, Chicago, IL 60605, USA 4BirdLife International, Wellbrook Court, Girton Road, Cambridge CB3 0NA, UK 5Department of Ornithology and Mammalogy, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA 94118, USA We investigated phylogenetic relationships among Otus scops owls from Socotra Island, the Arabian Peninsula and East Africa using molecular, vocalization and biometric data. The Socotra Scops Owl Otus senegalensis socotranus, currently treated as a subspecies of the African Scops Owl Otus senegalensis, is more closely related to the Oriental Scops Owl Otus sunia and to the endemic Seychelles Scops Owl Otus insularis. Considerable mitochondrial genetic distance and significant morphological differentiation from its two closest relatives, as well as its distinctive vocalizations compared with O. insularis, strongly support recognition of Socotra Scops Owl as a full species. Unexpectedly, two taxa from the Arabian Peninsula, Pallid Scops Owl Otus brucei and African Scops Owl Otus senegalensis pamelae, represent very distinct lineages; O. brucei is basal to a clade that includes taxa found in the Indo-Malayan region and on Indian Ocean islands. In contrast, O. s. pamelae occupies a well-supported basal position within a clade of conti- nental Afro-Palaearctic taxa. The uncorrected-p genetic distance between O. s. pamelae and its closest relatives (other populations of senegalensis from mainland Africa) is c. 4%. As O. s. pamelae is also well differentiated phylogenetically, morphologically and vocally from O. s. senegalensis, we recommend its elevation to species status, as Otus pamelae. Among mainland African O. senegalensis subspecies, Ethiopian populations appear to represent the most divergent lineage, whereas other lineages from Somalia, Kenya and South Africa are poorly differentiated. The large genetic distance between the Ethiopian haplotype and other African haplotypes (3.2%) suggests that the Ethiopian Otus may represent a cryptic taxon, and we recommend that more individuals be sampled to assess the taxonomic status of this population. Keywords: biogeography, Indian Ocean Islands, Indo-Malaya, phylogeny, Socotra Island, taxonomy. Scops owls (Otus, Strigidae) represent a genus of on small and remote islands. Despite high species small to medium-sized nocturnal birds with strong richness, the morphological diversity encountered colonizing capability, suggested by their presence within the genus is limited, with the occurrence of only two primary plumage colour types: rufous or *Corresponding author. grey. This lack of major plumage differences is Email: [email protected] common among members of the Strigidae and is © 2013 British Ornithologists’ Union 2 J.-M. Pons et al. usually explained by the need to remain inconspic- insularis formed a well-supported clade with uous during the day as a defence against predators Oriental Scops Owl Otus sunia (Fuchs et al. or from being mobbed by other birds (Marks et al. 2008). 1999). As a consequence of their highly conserved Samples of Socotra Scops Owl, currently con- morphology, it is unsurprising that the systematics sidered to be a subspecies of O. senegalensis, were of the genus Otus, as traditionally defined, have unavailable to Fuchs et al. (2008), and the same been challenged by molecular data (Fuchs et al. was true of several taxa found on the Arabian Pen- 2008, Wink et al. 2009, Miranda et al. 2011). insula (Pallid Scops Owl Otus brucei, and Otus sen- These studies suggested not only that the genus egalensis pamelae) and East Africa (northern Otus is polyphyletic, because the White-faced Somalia, Ethiopia, Kenya), where several subspe- Scops Owl Otus leucotis is sister to the genus Asio, cies of O. senegalensis have been described on the whereas the New World Screech Owls have affini- basis of differences in voice, plumage coloration ties with the genera Bubo, Strix and the Asio–Otus and size (Chapin 1930, Meinertzhagen 1948, leucotis clade (Fuchs et al. 2008), but also that Keith & Twomey 1968) but are not generally rec- species limits in some groups must be reconsidered ognized in the modern literature (Kemp 1988, due to either divergent mtDNA sequences Marks et al. 1999, Dickinson 2003, Konig€ et al. (Miranda et al. 2011) or paraphyly of traditionally 2008). The affinities of these taxa are still poorly recognized species (e.g. Collared Scops Owl O. let- known and this uncertainty is reflected by frequent tia; Fuchs et al. 2008). changes in their taxonomic treatment (Marks et al. As currently understood, the genus Otus has its 1999, Konig€ et al. 2008). Since Sclater (1924), the centre of diversity in the Palaearctic and Oriental Socotran population has usually been treated as a (Indo-Malayan) regions (26 species). Secondary subspecies of O. senegalensis (Otus senegalensis soco- radiations have occurred on the Indian Ocean tranus), but it is sometimes placed together with islands, which are occupied by six species, and in Pallid Scops Owl O. brucei (e.g. Kemp 1988, Africa with four mainland species (Eurasian Scops Konig€ et al. 1999), whose range otherwise encom- Owl Otus scops, African Scops-Owl Otus senegal- passes the eastern part of the Arabian Peninsula ensis, Sokoke Scops Owl Otus ireneae, Sandy extending east to western Pakistan and north to Scops Owl Otus icterorhynchus) and two insular southeastern Turkey and Central Asia (Marks et al. species (S~ao Tome Scops Owl Otus hartlaubi, 1999). This taxon’s treatment as a subspecies of Pemba Scops Owl Otus pembaensis) (Marks et al. O. senegalensis appears to have been influenced by 1999). the report ‘that the song on Socotra is identical to Fuchs et al. (2008) suggested that the rapid that in Kenya’ (A. Forbes-Watson in Marshall divergence following the initial colonization of the 1978). However, recently Konig€ et al. (2008) and Indian Ocean islands (Madagascar and the Como- Porter and Aspinall (2010) considered socotranus ros archipelago) led to distinctive genetic lineages, to represent a separate species. and this result has favoured the recognition of Similarly, scops owls from southern Arabia, cur- each insular Otus taxon as a distinct species rently recognized as Otus senegalensis pamelae, (Fig. 1). Intriguingly, molecular DNA sequence have also been suggested to be closely related to data suggest that several species have strikingly O. brucei (Marks et al. 1999), although Marshall different affinities than recognized under tradi- (1978) already noted that this taxon’s vocalizations tional hypotheses, suggesting that morphology and are ‘intermediate between the stutter of Otus sen- vocalizations are weak characters with which to egalensis senegalensis and the purr of O. sunia di- define phylogenetic relationships in scops owls. stans of Thailand.’ Furthermore, the systematic For example, O. pembaensis proved not to be con- affinities of O. brucei remain unclear. It has been specific with Madagascar Scops Owl Otus rutilus, treated either as a subspecies of Otus scops (Mein- contrary to previous hypotheses (Marks et al. ertzhagen 1948) or Otus sunia prior to vocal stud- 1999), but instead is closely related to mainland ies that supported its specific status (Marshall O. senegalensis (Fuchs et al. 2008). Likewise, the 1978, Roberts & King 1986). S~ao Tome endemic Otus hartlaubi was found to We here examine further the patterns of pheno- have strong affinities with O. senegalensis. Even typic differentiation among scops owl taxa, more surprisingly, the Seychelles Scops Owl Otus and discuss these with respect to phylogenetic © 2013 British Ornithologists’ Union Systematics of Otus scops owls 3 Afro-Palaearctic clade Indo-Malayan/Indian Ocean clade Figure 1. Map depicting the geographical range of Otus taxa in the region of interest. Afro-Palaearctic clade: A1 = Otus senegalen- sis pamelae;A2= Otus scops;A3= Otus pembaensis;A4= Otus hartlaubi;A5= Otus senegalensis. Indo-Malayan/Indian Ocean clade: i1 = Otus brucei;i2= Otus moheliensis;i3= Otus pauliani;i4= Otus capnodes;i5= Otus mayottensis;i6= Otus rutilus; i7 = Otus madagascariensis;i8= Otus senegalensis socotranus;i9= Otus insularis; i10 = Otus sunia. relationship highlighted by our analyses of mito- Two mitochondrial markers, nicotinamide chondrial and nuclear sequence data. dehydrogenase subunits 2 and 3 (ND2, ND3), and two nuclear introns (myoglobin intron-2 (MB) and TGFb2 intron-5 (TGFb2)) were METHODS amplified via the polymerase chain reaction We collected blood samples for the Socotra Scops (PCR) and sequenced. ND2 and ND3 were Owl and used toe-pads from museum specimens PCR-amplified and sequenced using primer pairs held at the Natural History Museum, Tring, UK, L5219/H6313 (Sorenson et al. 1999) and for O. brucei, O. s. pamelae and O. s. senegalensis L10755/H11151 (Chesser 1999), respectively. collected in Ethiopia, Somalia and Kenya. In addi- The MB nuclear intron was PCR-amplified and tion, our taxonomic sampling