Tanygnathus

O’Connell, Darren P., Kelly, David J., Kelly, Seán B. A., Analuddin, Kangkuso, Karya, Adi, Marples, Nicola M., Rheindt, Frank E. & Martin, Thomas E., 2020, An assessment of the avifauna of the Wakatobi Islands, South-east Sulawesi, Indonesia: species recorded and taxonomic considerations, Raffles Bulletin of Zoology 68, pp. 574-587 : 578-579

Great-billed Parrot Tanygnathus megalorynchos megalorynchos. The Wakatobi population of Great-billed Parrot was described by Hartert (1903) as an endemic subspecies, T. m. viridipennis, although it has subsequently been combined with several other Great-billed Parrot populations from the Lesser Sundas and satellite islands of New Guinea to form the wide-ranging T. m. megalorynchos. It likely suffers from trapping to feed the Indonesian pet trade

( Harris et al., 2017), but was encountered either Commonly or Occasionally throughout the larger Wakatobi Islands ( Table S1), usually flying between patches of forest.

Black-naped Oriole Oriolus chinensis celebensis. The Wakatobi population of Black-naped Oriole was described by Hartert (1903) as an endemic subspecies, O. c. oscillans. It has since been synonymised with other Sulawesi populations as the subspecies O. c. celebensis ( Eaton et al., 2016; Gill & Donsker, 2020). However, the taxonomy of this species is in flux and this designation is likely to change ( Jønsson et al., 2010; Eaton et al., 2016). The Black-naped Oriole was found to be Abundant in a variety of habitats throughout the Wakatobi Islands during our survey work ( Table S1). Captured during mist netting nine times in total, on Runduma (4), Hoga (3), Binongko (1), and Kaledupa (1) (Table S2).

Wallacean Cicadabird Edolisoma amboinensis pererrata *. This population has previously been classified as a subspecies of Slender-billed Cicadabird Edolisoma tenuirostre pererratum endemic to the Wakatobi Islands ( Hartert, 1916; White & Bruce, 1986; Coates & Bishop, 1997; Billerman et al., 2020). However, the recent detailed molecular assessment of the Edolisoma tenuirostre / remotum species complex by Pedersen et al. (2018) has shown the Wakatobi population to be a part of the Wallacean Cicadabird as in Eaton et al. (2016). An individual male was captured during mist netting and photographed by the authors (ML718272), supporting this assessment, showing the characteristic darker plumage of this species. The species was encountered in scrub or forest habitat, Commonly on Wangi-wangi and Hoga, Occasionally on Kaledupa and Tomia, and Rarely elsewhere ( Table S1).

Sulawesi Triller Lalage leucopygialis *. Trillers on the Wakatobi Islands were previously identified as belonging to the Lesueur’s Triller Lalage sueurii ( White & Bruce, 1986; Coates & Bishop, 1997; Eaton et al., 2016; Billerman et al., 2020). However, all individuals clearly identified on the Wakatobi Islands by the authors were Sulawesi Trillers. Both the Lesueur’s Triller and Sulawesi Triller are found on nearby Buton ( Martin et al., 2012), whereas on more isolated Menui Island only the Sulawesi Triller is found ( Monkhouse et al., 2018), as was found to be the case on the Wakatobi Islands. Notes taken during field observations refer to individuals having a fairly broad supercilium, large white rump and a white wing panel definitely encompassing the tertials. In addition, their song was a chattering series consistent with the Sulawesi Triller, not a melodious series as in the Lesueur Triller. The species was encountered Occasionally–Abundantly in forest, scrub, and mangrove habitats throughout the main Wakatobi Islands ( Table S1). A single individual was captured during mist netting on Kaledupa (Table S2).

Wakatobi White-eye Zosterops flavissimus *. The Wakatobi population of Lemon-bellied White-eye was described by Hartert (1903) as a new species, Zosterops flavissimus, but later demoted to subspecies level within the Lemonbellied White-eye as Z. chloris flavissimus by most modern sources ( Eaton et al., 2016; Billerman et al., 2020). Recently

O’Connell et al. (2019c) combined genetic, morphological, bioacoustic, and plumage comparisons to find that flavissimus had been separate from the mainland Sulawesi population for 400–800,000 years, is smaller in body size, has a brighter yellow plumage with a unique orange forehead patch (Macaulay Library ML718273), and has diverged in song structure, singing at a higher frequency with more notes. These results confirmed the veracity of Hartert’s (1903) original decision to describe this form at the species level. O’Connell et al. (2019c) proposed the common name Wakatobi White-eye for this species. This designation is already recognised by the IOC World Bird List Version 10.1 ( Gill & Donsker, 2020). Intriguingly, the isolated Runduma Island population seems to represent a separate independent colonisation event of Lemon-bellied White-eyes Z. chloris, not Wakatobi White-eyes Z. flavissimus, from the closest ‘mainland’ population (Z. c. intermedius) on the larger island of Buton, within the last 10–20,000 years ( O’Connell et al., 2019c). Buton Island is ca. 123 km from Runduma, as opposed to the ca. 54 km between the Kaledupa Island population of Wakatobi White-eye Z. flavissimus and Runduma ( Fig. 1 ). The Runduma population is larger in body size than either Z. c. intermedius or the Wakatobi White-eye, and exhibits some modest mitochondrial divergence from both ( O’Connell et al., 2019c). This isolated population may warrant further investigation of other potential ecological differences. Therefore, the Wakatobi archipelago hosts two Zosterops species from this lineage, the Wakatobi White-eye Zosterops flavissimus on the main chain of the Wakatobi Islands (Wangi-wangi, Kapota, Oroho, Kaledupa, Tomia, Lintea Selatan, and Binongko), and a Lemon-bellied Whiteeye Zosterops chloris population on remote Runduma Island. The Wakatobi White-eye is Abundant throughout the core Wakatobi Islands in large numbers ( Table S1), except on Hoga Island, where it is curiously absent, despite only a ca. 2.5 km gap to the population on Kaledupa. Nearly half of all birds mist netted (511/1096) were Wakatobi White-eyes (Table S2), and their capture rate on Tomia (0.058 individuals per metre hour netting effort) was more than twice that of any other population’s capture rate on the Wakatobi Islands (Table S3).

Wangi-wangi White-eye (undescribed Zosterops ) *. A remarkable recent find for modern ornithology; a novel Zosterops species found only on densely populated Wangi-wangi Island. This population is a distinct species in morphology and genetics ( O’Connell et al., 2019c). It quickly caught the attention of DJK and NMM during their first visit to Wangi-wangi in 2003 ( Kelly & Marples, 2010), due to its distinctive large yellow bill (Macaulay Library ML718276), setting it apart from all other Zosterops species in the region. Unexpectedly, this species is even absent from Wangi-wangi’s close satellite islands of Oroho and Kapota. The reason for this is unknown, particularly as the habitats of Wangi-wangi are generally highly degraded, so it is unlikely to relate to the presence of pristine habitat. This bird was likely overlooked by Kühn as he spent only a very short time on Wangi-wangi due to various bureaucratic hurdles ( Hartert, 1903). The fact that no museum material exists for this species has delayed its description. Anecdotal reports already suggest that this new species is being traded at Indonesian bird markets, its novelty attracting buyers (P. Akbar, pers. comm.). This phenomenon has previously been noted in reptile species awaiting formal description ( Losos, 2018). This species is at its most abundant in Wangi-wangi’s remaining patches of relatively intact forest and was found to be strongly associated with the thick tangles, epiphytes and vines on emergent large trees. However, it also seems tolerant of degraded habitat, and was found to be Common in inland scrub, overgrown farmland and forest edge habitats ( Table S1); in the 18 mist netting sessions conducted in those habitats, 20% of birds caught were ‘Wangi-wangi White-eyes’, with 48 individuals captured in total (Table S2). However, the fact that it is constrained to a single small island (155 km 2) makes it intensely vulnerable to persecution; a process that already appears to be happening. We highlight the formal taxonomic description and subsequent conservation status assessment of this species as an urgent conservation priority; an outcome that is likely to see this species listed as Endangered as it occupies an area of <500 km 2 (IUCN, 2012). Such recognition is a vital step towards ensuring legislation can be put in place to see the species effectively protected. We hope that this occurs before it is too late, the extinction of a species before it has been described not being an unprecedented occurrence ( Lees & Pimm, 2015).

Grey-sided Flowerpecker Dicaeum celebicum kuehni *. The Wakatobi population of Grey-sided Flowerpecker was described by Hartert (1903) as a new, endemic species, Dicaeum kuehni. This treatment was disregarded by modern accounts, most of which relegated it to subspecies level within the Grey-sided Flowerpecker D. celebicum. Kelly et al. (2014) proposed returning the Wakatobi population to full species rank (the Wakatobi Flowerpecker Dicaeum kuehni). This recommendation was made on the basis of genetic differences, the larger body size of the Wakatobi populations, its slightly blue-washed purplish upperparts, and greater extent of frontal red and paler grey flanks, in comparison with mainland Sulawesi D. c. celebicum. Most modern sources (e.g., Eaton et al., 2016; Billerman et al., 2020; Gill & Donsker, 2020) have yet to accept this designation, and bioacoustic analyses will likely be necessary to confirm the veracity of this split. It is present throughout the Wakatobi Islands and is generally Abundant ( Table S1), apart from Runduma where it is absent. A total of 30 individuals were captured during mist netting across the islands (Table S2).

Sahul Sunbird Cinnyris clementiae infrenatus. The Wakatobi population of the Sahul Sunbird was described by Hartert (1903) as an endemic species, Cinnyris infrenatus, but most modern accounts reclassified it as a subspecies either of the Olive-backed Sunbird Cinnyris jugularis infrenatus (Billerman et al., 2020; Gill & Donsker, 2020) or of the geographically more limited Sahul Sunbird C. clementiae infrenatus ( Eaton et al., 2016). The later treatment seems likely to be widely adopted in the coming years due to the distinct differences in genetics and phenotype between the Sahul Sunbird and other populations of the “Olive-backed Sunbird” umbrella species ( Eaton et al., 2016). Cinnyris clementiae infrenatus shows distinct plumage differences from the mainland Sulawesi form C. c. plateni, with male C. c. infrenatus lacking the moustachial and superciliary stripe of C. c. plateni, and females having reduced superciliary stripes (Macaulay Library ML718266) ( Kelly & Marples, 2011; Kelly, 2014; Billerman et al., 2020). In addition, C. c. infrenatus is smaller, and shows greater sexual dimorphism in morphology than C. c. plateni ( O’Connell et al., 2019a). The taxonomy of the Sahul Sunbird as a whole is in flux, and several populations will likely be split from it in the coming years ( Eaton et al., 2016; Billerman et al., 2020), potentially including the Wakatobi population. In contrast to the Lemon-bellied White-eye population, the Sahul Sunbird population on Runduma seems to have originated from the main Wakatobi Islands, rather than the Sulawesi mainland, based on plumage comparisons and preliminary genetic work ( Kelly & Marples, 2010; Kelly, 2014). This species is ubiquitous throughout the Wakatobi Islands and is generally Abundant ( Table S1), with 205 individuals captured during mist netting (Table S2).

Figures

Fig. 1. Location of the Wakatobi Islands in relation to mainland South-east Sulawesi and its other offshore islands. The inset shows the location of the South-east Sulawesi region within Indonesia and the wider region.