Ficedula hyperythra betinabiru, Rheindt & Prawiradilaga & Ashar & Lee & Wu & Ng, 2020

Rheindt, Frank E., Prawiradilaga, Dewi M., Ashar, Hidayat, Lee, Geraldine W. X., Wu, Meng Yue & Ng, Nathaniel S. R., 2020, A lost world in Wallacea: Description of a montane archipelagic avifauna (supplement), Science 36, pp. 1-104 : 68-72

SM11:

Ficedula hyperythra betinabiru , subspecies nova

(Taliabu Snowy-browed Flycatcher;

urn:lsid:zoobank.org:act:6DE2022E-82E4-4478-B0C2-D3AC9505C31A)

Frank E. Rheindt, Dewi M. Prawiradilaga, Hidayat Ashari, Suparno

Holotype

MZB.Ornit.34.377 (fig. S15); adult male collected 10 Dec 2013 at Waiyo dinahana Camp (~ 1200m) above Wahe village on Taliabu Island (S 01⁰ 47.614 '; E 124⁰ 48.216 '). Collected by the Rheindt / LIPI field party, including tissue samples from breast muscle and liver; skin prepared by Suparno; field number Tbu44; no body and wing molt; medium fat; weight 11.5g; wing length 6.4cm; wing spread 17.7cm; total length 10.5cm; bill 1.1cm; tail 4.9cm; tarsus 2.1cm.

Description of holotype

Forehead to crown and nape dark slaty blue (2.5PB 2/2) with slightly scaly appearance generated through narrow black feather centres; the same color, but without the scaly appearance, then continues through mantle and scapulars to rump. A white supercilium starts above the centre of the eye and ends just shy of the bill base, becoming narrower towards the front. A black facial patch centred in the loral region and below the supercilium to the chin (with narrow rows of black feathers above the bill base) grades into dark slaty blue coloration (2.5PB 1.5/2) towards the auriculars and the malar and moustachial regions, merging with the nape and mantle. Upperwing coverts largely concolorous with crown, with vestiges of an extremely indistinct brighter carpal patch visible with difficulty on this specimen. Remiges are dark slaty brown (10YR 2.5/1), the larger primaries with warmer, paler outer edging (10YR 4/2). Breast intensely rufous (7.5YR 7/12), becoming slightly paler on throat and upper flanks, and becoming pale cinnamon-whitish on belly and lower flanks (7.5YR 9/4), and eventually off-white on undertail coverts. Tail dull black on upper side, blackish-grey (N2) on underside, with indistinct white base to outermost rectrices. Iris dark-brown; legs light-pink; black bill with pinkish gape flange on live bird.

Diagnosis

An unequivocal member of the Snowy-browed Flycatcher Ficedula hyperythra , and one of its most easterly outposts, with minor plumage distinctions in the male and major plumage distinctions in the female, a combination of which conclusively demarcates this new taxon from other subspecies.

The male subtly differs from adjacent insular subspecies to the south and to the west, namely from the two Sulawesi subspecies (jugosae, annalisa), from sumatrana (Sumatra, Peninsular Malaysia, Borneo), from vulcani (Java, Bali, Lombok, Sumbawa, Flores), and from alifura (Buru), in the reduction of white patches at the base of the outer tail feathers, and in the slightly less extensive rufous underparts, replaced on the belly by pale cinnamon- whitish. In contrast, males of the only subspecies to the east and north (pallidipectus from Bacan Island) are markedly paler on the underparts than the males of this new subspecies, and have more contrastingly olive flanks. The white supercilium in males of the new subspecies is narrower than that of at least sumatrana, vulcani, and alifura.

The female is highly distinct from most subspecies of F. hyperythra in her bluish (versus olive, brown or grey-brown) upperparts coloration, extensive cold-brown mottling on breast (versus little to none), and a washed-out face pattern ghosting that of the male, with a whiter (versus rufous) brow. The only other subspecies that equals female F. h. betinabiru in her bluish tinge to the upperparts is alifura from adjacent Buru, in which the back color is ever so slightly brighter-blue. Compared to the new subspecies, the female of alifura exhibits a more rufous (less white) eye brow, and brighter and more extensive rufous underparts with less brown mottling.

Etymology

The subspecific epithet comprises the words for “blue female” in Bahasa Indonesia (betina biru), drawing attention to the bluish upperparts in females of this subspecies, a rare trait within the species. The name is a noun in apposition.

Individual, sex and age-related variation within the taxon

Only adult specimens have been procured, although a photo of a pullus near the nest suggests an early juvenile plumage similar to other subspecies. Among adults, tarsus color as recorded in the field on live birds appears to vary individually from light-pink to pinkish-horn.

There is minor variation among the nine adult male specimens procured in the lower extent of the rufous breast, the intensity of the cinnamon wash to the belly, thickness of the supercilium and the extent of vestigial white patches on the basal outer rectrices. There is minor variation among the five adult female specimens in the intensity of brown mottling on the underparts, width and paleness of the supercilium and the presence or absence of a slight brownish tinge to the lowermost mantle portion.

History of discovery

This new subspecies of Snowy-browed Flycatcher was first encountered by the University of East Anglia expedition to Taliabu in 1991 (64, 9 8). Members of that survey found the new taxon predominantly at the highest altitude they reached (roughly 800m) and suggested that it may be a novel subspecies. FER then saw one adult male at 1100m during his visit to the highlands of western Taliabu on 5 April 2009 ( 48). We returned to this general area between 6-16 December 2013, where we found betinabiru as one of the most common constituents of the forest interior understorey avifauna and collected the type and accompanying individuals at ~1300m ( 19).

Distribution and status

Subspecies betinabiru is currently only known from the understorey of dense montane forest in the highlands of Taliabu at above 800m elevation (19, 48, 64, 9 8). Extensive logging has occurred across the highlands of Taliabu, with some parts of the mountains additionally affected by large-scale forest fires (see Taliabu Grasshopper-Warbler account in SM3; fig. S2 ). As an understory inhabitant, betinabiru would be particularly susceptible to this kind of habitat degradation and is therefore probably declining. Nevertheless, it remains extremely common where good habitat persists, as indicated by our high mistnet capture rates ( 19).

To the best of our knowledge, Snowy-browed Flycatchers have not been detected on the two other main islands of the Sula Archipelago, although their occurrence is possible at least on Mangole, which rises to 1,127m, while very unlikely on Sanana, which does not rise taller than ~600m. If confirmed on Mangole, it is likely that the local population would refer to the same subspecies betinabiru.

On the adjacent Banggai Archipelago, a single Snowy-browed Flycatcher was recorded once in April 2009 at 800-900m on the tallest island of Peleng ( 49). To the best of our knowledge, there have not been subsequent records from this island despite extensive fieldwork. In the absence of photos or closer details about the single Peleng record, it is impossible to ascertain whether the Peleng population is ascribable to betinabiru, to one of the two Sulawesi races (annalisa, jugosae) or to a novel unnamed subspecies.

Taxonomic rationale

We describe this new taxon on the basis of its characteristic plumage (especially in females). These plumage distinctions certainly warrant a description at the subspecific level as they exceed those of several more poorly marked subspecies within this complex (e.g. annalisa [Stresemann, 1931], which only subtly differs from jugosae [Riley, 1921]). Bioacoustic variation in this species complex is poorly explored, but the high-pitched courtship vocalization of the new subspecies superficially resembles that of many other subspecies, and playback of songs from other subspecies elicits a ready response from members of this population. Genetic differences between the new taxon and other subspecies remain unexplored.

Figures

Fig. S2. Google Earth satellite map of Peleng and Banggai (top) and the western half of Taliabu (bottom). Peleng and Banggai are the two largest islands of the “Banggai Archipelago”. Our main collection site, an unnamed locality “above Kokolomboi [village]”, is mapped with a yellow pin. Areas above 800m elevation are circled with a red line, indicating the presence of montane vegetation. The island of Taliabu is the largest member of the “Sula Archipelago”. Our main collection locality “Waiyo dinahana” is mapped with a yellow pin. Areas above 1,050 m elevation are circled with a red line, indicating the presence of a peculiar montane stunted forest vegetation. Within the montane zone above 1,050m, areas degraded by logging activity as reflected on Google Earth satellite imagery are mapped in turquoise and areas burnt down by extensive fires in the 1980s are mapped in dark-green. Given the outdated status of some of the satellite imagery, present-day forest degradation is likely more extensive than shown.