Frontiers of Taxonomy:<\/span>\u00a0 Parsing the Purple Swamphens<\/em><\/strong><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t African Swamphen<\/a>.\u00a0 \u00a9 Mark Samuelsson<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t The Purple Swamphen (Porphyrio porphyrio<\/em>), as traditionally classified, is a group of related forms scattered across the Old World and Pacific Islands from Portugal to Samoa.\u00a0 This group is visibly diverse and has long been suspected of including multiple species.\u00a0 Three subspecies in particular\u2014those of the western Mediterranean (Western<\/strong>, porphyrio<\/em>), Africa and Madagascar (African<\/strong>, madagascariensis<\/em><\/a>), and the Philippines (Philippine<\/strong>, pulverulentus<\/em>)\u2014are readily identifiable by sight, and seem natural candidates for recognition as separate species.\u00a0 The remaining nine subspecies\u2014those of Asia, Indonesia, Australasia, and Oceania\u2014are also diverse but not as clearly distinguishable, as their features appear to blend from one group into the next.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t Odd Branches on the Family Tree.<\/em><\/strong>\u00a0 A genetic analysis published in 2015 (Garc\u00eda-R. and Trewick) validated the three readily identifiable forms and also produced an unexpected result that points to a three-way split of the remaining subspecies: in Asia (Gray-headed<\/strong>, poliocephalus<\/em><\/a>); in Indonesia (Black-backed<\/strong>, indicus<\/em>); and eastward (Australasian<\/strong>, melanotus<\/em>).<\/p> The surprise was that the geographically central and apparently transitional form, the Black-backed Swamphen of Indonesia, is not the closest relative of any of its neighbors.\u00a0 Instead, all of its neighbors are more closely related (by ancestry, as measured by mitochondrial RNA markers) to one another and to a very different species, the huge, flightless, tailless South Island<\/strong> Takahe<\/strong> (P. hochstetteri<\/em>) of New Zealand, which naturally occurs alongside the Australasian Swamphen.<\/p> The logical inference seems straightforward: if Black-backed is a distant branch of the family tree, more distant than the obviously separate Takahe, then Black-backed must also be separate from the others, and therefore apparently serves as a wedge rather than a bridge between the dissimilar Asian and Australasian populations.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t Australasian Swamphen, P.<\/em> melanotus<\/em>.\u00a0 (Westgate Park, Melbourne, Victoria, Australia; July 14, 2018.) \u00a0\u00a9 Dan Forster<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t South Island Takahe, flightless and tailless.\u00a0 (Zealandia Wildlife Sanctuary, Wellington, North Island, New Zealand; September 22, 2019.) \u00a0\u00a9 Andr\u00e9 Zambolli<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t South Island Takahe, showing its small frontal shield and purple, turquoise, green, and bronze coloration.\u00a0 (Orokonui Ecosanctuary, Dunedin, South Island, New Zealand; July 19, 2020.) \u00a0\u00a9 Oscar Thomas<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t \u00a9 BirdLife International 2019<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t Garc\u00eda-R. and Trewick\u2019s research indicates a subdivision of the former Purple Swamphen into a total of six species, plus three more based on their genetic proximity\u2014although two of the additional three are extinct.\u00a0 Starting from the oldest divergent branch in the family tree, they are:<\/p> Western Swamphen<\/strong> (Porphyrio porphyrio<\/em>)<\/p> Black-backed Swamphen<\/strong> (P. indicus<\/em>)<\/p> African Swamphen<\/strong> (P. madagascariensis<\/em>)<\/a><\/p> North Island Takahe<\/strong> (P. mantelli<\/em>) \u2020<\/p> South Island Takahe<\/strong> (P. hochstetteri<\/em>)<\/p> Australasian Swamphen<\/strong> (P. melanotus<\/em>)<\/p> Gray-headed Swamphen<\/strong> (P. poliocephalus<\/em>)<\/a><\/p> Philippine Swamphen<\/strong> (P. pulverulentus<\/em>)<\/p> White Swamphen<\/strong> (P. albus<\/em>) \u2020<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t Some authorities have adopted this proposal and some have questioned it.\u00a0 The main source of skepticism has been the apparent difficulty of drawing lines between Gray-headed and Black-backed due to apparent intergradation.\u00a0 Less clear is the possibility that Black-backed and Australasian might not be distinguishable in the field.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t Philippine Swamphen, slaty-gray overall with a brown back.\u00a0 (Agusan Marsh Wildlife Sanctuary, Loreto, Mindanao, Philippines; November 26, 2015.) \u00a0\u00a9 Erickson Tabayag<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t Western Swamphen, showing all-coral-pink legs and violet upperparts.\u00a0 (S\u2019Albufera, Mallorca, Spain; September 22, 2018.) \u00a0\u00a9 Guido Bennen<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t African Swamphen, showing all-coral-pink legs and bronze-green upperparts.\u00a0 (Marievale Bird Sanctuary, Gauteng, South Africa; August 4, 2018.) \u00a0\u00a9 Richard Gray<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t Australasian Swamphen, P. m. melanotos<\/em>, showing dark knees and black upperparts.\u00a0 (Western Springs Park, Auckland, New Zealand; July 28, 2018.) \u00a0\u00a9 Oscar Thomas<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t An Easy Problem in Southeast Asia.<\/em><\/strong>\u00a0 Attention has been misplaced on the variable populations native to Southeast Asia, from northern Thailand and southern China south to Sumatra and Singapore, collectively classified as the subspecies viridis<\/em>.\u00a0 Confusion about the significance of this variation apparently began from a presumption (of uncertain origin) that viridis<\/em> was part of the Black-backed group.\u00a0 Field observers immediately knew that this couldn\u2019t be right, for the simple reason that most viridis<\/em> have unambiguously gray heads.\u00a0 A related, but less significant cognitive problem is that many viridis<\/em> also have black backs, which seems to imply that Gray-headed and Black-backed cannot be separate species (or at the very least that these names are hopelessly misleading).<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t Gray-headed Swamphen, a dark individual with a blue-and-purple head.\u00a0 (Khateshwar Tank, Yavatmal, Maharashtra, India; April 29, 2013.) \u00a0\u00a9 Jayant Atrey<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t Taking a broader view, however, the range of variation observed in viridis<\/em> occurs to some degree throughout the Asian populations traditionally classified as poliocephalus<\/em> (mainly those of the Indian subcontinent).\u00a0 In other words, when considered as a species widespread from Turkey to Sumatra and Singapore, Gray-headed is highly variable in many conspicuous aspects of its coloration\u2014including but not limited to the head and back\u2014so while viridis<\/em> certainly varies widely, its variation appears to be consistent with the variation observed elsewhere in Asia.<\/p> The obvious solution\u2014which quickly became consensus\u2014is to regard viridis<\/em> as conspecific with poliocephalus<\/em>.\u00a0 This revision seems uncontroversial, but it still leaves the fundamental ambiguities unresolved.\u00a0 Is there a line be drawn between Gray-headed viridis<\/em> and Black-backed indicus<\/em>? \u00a0On the other side of indicus<\/em>, is there a line between Black-backed and the various Australasian populations? \u00a0Do we classify them as three, two, or one species?<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t Gray-headed Swamphen, a pale individual with a whitish-gray head.\u00a0 (Nong Bong Kai Wildlife Refuge, Chiang Rai, Thailand; February 20, 2019.) \u00a0\u00a9 Elizabeth Skakoon<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t Black-backed Swamphen, P. indicus<\/em>, showing its typical plumage, which is approximately intermediate between Gray-headed and Australasian.\u00a0 (Muara Angke, Jakarta, Java, Indonesia; April 22, 2019.) \u00a0\u00a9 Lars Petersson<\/a><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t A Harder Problem in Indonesia.<\/em><\/strong>\u00a0 The central problem in swamphen reclassification is what to make of indicus<\/em>, the Black-backed Swamphen.\u00a0 Visually, it appears to be a transitional form that blends into the neighboring Asian and Australasian populations, but genetic markers indicate that it has maintained a wholly separate identity for millions of years despite its inevitable interaction with those similar-looking populations.<\/p> If there are lines to be drawn on either side of indicus<\/em>, they are difficult to ascertain\u2014in part because information about populations that occupy potentially transitional areas is sparse, and in part because the available information seems to provide at least superficial evidence of intergradation.<\/p> To the west, although viridis<\/em> is clearly allied with the Gray-headed, there is evidence of possible hybridization (or perhaps merely cohabitation) between viridis<\/em> and indicus<\/em> on the southern Malay Peninsula and Sumatra.\u00a0 So the reassignment of viridis<\/em> to Gray-headed merely pushes the gray area southward.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t![\"\"](\"https:\/\/birdfinding.info\/wp-content\/uploads\/2020\/09\/AfricanSwamphen3.jpg\")
\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t![\"\"](\"https:\/\/birdfinding.info\/wp-content\/uploads\/2020\/09\/AustralasianSwamphen3.jpg\")
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\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t![\"\"](\"https:\/\/birdfinding.info\/wp-content\/uploads\/2020\/09\/WesternSwamphen1.jpg\")
\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t![\"\"](\"https:\/\/birdfinding.info\/wp-content\/uploads\/2020\/09\/AfricanSwamphen1.jpg\")
\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t![\"\"](\"https:\/\/birdfinding.info\/wp-content\/uploads\/2020\/09\/AustralasianSwamphen2.jpg\")
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