1392_60-2_09 281..298 281 New Species of Rails (Aves: Rallidae) from an Archaeological Site on Huahine, Society Islands1 Jeremy J. Kirchman2,4 and David W. Steadman3 Abstract: We examined 50 bones previously assigned to ‘‘Gallirallus new sp.’’ from the prehistoric (1,250–750 yr B.P.) Fa‘ahia archaeological site on Huahine, Society Islands. Most of these specimens ðn ¼ 47Þ, representing nearly all major cranial and postcranial skeletal elements, belong to a medium-sized flightless rail that we name Gallirallus storrsolsoni. Three femora represent a second species of extinct rail that we name Porphyrio mcnabi. With the description of these two species of rails, the total number of extinct species of land birds from the Fa‘a- hia site stands at seven, consisting of two rails, two doves, two parrots, and a starling. Fa‘ahia also has yielded bones of six other species of land birds that no longer exist on Huahine but survive elsewhere in Oceania. Fossil bones from archaeological and paleontological sites on islands throughout Oceania have revealed extensive Holocene extinction of birds after colonization by hu- mans and their commensals ( James and Ol- son 1991, Olson and James 1991, Steadman 1995, in press, Worthy and Holdaway 2002). On a typical island in East Polynesia (Figure 1), 50 to 100% of the species of land birds that existed at human contact do not survive there today (Steadman in press). Especially prevalent among the East Polynesian extinct species are rails (Rallidae), most of which were flightless species endemic to single is- lands or to islands connected in the Pleisto- cene during periods of lowered sea levels. In this paper we describe two new species of rails from the Fa‘ahia archaeological site on Huahine in the Society Islands. The Fa‘ahia site (Figure 2) was excavated by Yosihiko H. Sinoto and colleagues from 1973 to 1984 in cooperation with the Départ- ment de Archéologie, Centre Polynésien des Sciences Humaines, Tahiti (dapt). The cul- tural deposits at Fa‘ahia were found sub- merged below the modern water table and contained exceptionally well-preserved or- ganic materials, including wooden adze handles, tapa beaters, and parts of canoes (Sinoto 1975, 1979). Other objects preserved and recovered from Fa‘ahia include non- human bones representing food items of all sizes (fishes, reptiles, birds, and mammals) and a wide variety of artifacts and ornaments made of bone, shell, or stone. By East Poly- nesian standards, Fa‘ahia is an early occupa- tion site with radiocarbon dates ranging from ca. 1,250 to 750 yr B.P. (¼ ca. A.D. 700 to 1200 [Sinoto 1983]). We note, however, that the chronology of human colonization in East Polynesia (the Cook Islands eastward, including the Society Islands) has been de- bated for decades (Sinoto 1970, Kirch 1984, 1986, 2000, Spriggs and Anderson 1993, Conte and Anderson 2003). Archaeological sites older than A.D. 1000 are scarce or ab- sent in East Polynesia, although sedimento- logical and paleobotanical information suggests that people were present in the Soci- ety Islands and Cook Islands at least several centuries earlier than A.D. 1000 (Lepofsky et al. 1992, 1996, Kirch and Ellison 1994, Lep- ofsky 1995). In spite of uncertainty in the Pacific Science (2006), vol. 60, no. 2:281 – 297 : 2006 by University of Hawai‘i Press All rights reserved 1 Financial support came from a McGlaughlin Fel- lowship to J.J.K. from the University of Florida College of Liberal Arts and Sciences, and NSF grants EAR- 9714819 and DEB-0228682 to D.W.S. Manuscript ac- cepted 20 June 2005. 2 Department of Zoology, University of Florida, Gainesville, Florida 32611. 3 Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611. 4 Corresponding author: e-mail: jkirchman@zoo .ufl.edu; phone: 352-392-1721 x232; fax: 352-392-3704. F i g u r e 1 . O ce an ia . D as h ed li n e in d ic at es th e E as t P o ly n es ia fa u n al re g io n . chronology of first arrival, there is a consis- tent pattern of heavy exploitation of native birds early in the archaeologically preserved cultural sequence in East Polynesia, which typically begins at ca. A.D. 1000 (Dye and Steadman 1990, Kirch et al. 1995, Steadman and Rolett 1996). In yielding bird bones that mainly represent extinct species, the zooarch- aeological evidence from Fa‘ahia agrees with this pattern. Over 300 bird bones were obtained at Fa‘ahia by screening the sediment through 0.25-in. (6.4-mm) mesh. Of 53 rail bones reported by Steadman and Pahlavan (1992), three were from Porzana tabuensis, a small species that is widespread in Polynesia but that no longer occurs on Huahine. The other 50 bones were assigned to a larger, presum- ably undescribed, flightless rail, referred to as ‘‘Gallirallus new sp.’’ These 50 specimens are the basis of this paper. materials and methods Skeletons used for comparisons are from the American Museum of Natural History (amnh), Bernice P. Bishop Museum (bpbm), Delaware Museum of Natural History Figure 2. Society Islands, with inset of Huahine showing the location of the Fa‘ahia archaeological site. Fossil Rails from Huahine . Kirchman and Steadman 283 (dmnh), Florida Museum of Natural History, University of Florida (uf), University of Michigan Museum of Zoology (ummz), Na- tional Museum of Natural History, Smith- sonian Institution (usnm), University of Washington Burke Museum (uwbm), and Yale Peabody Museum (ypm). We examined these modern specimens: Porzana (Poliolim- nas) cinerea, dmnh 72836, 72906; Porzana ta- buensis, uwbm 42501; Gallirallus striatus, amnh 22981, usnm 85892, 559919, ypm 107205; G. torquatus, amnh 17715–17717, ummz 228275, 228280, usnm 290445; G. owstoni, uf 39918, 39920, 39921, usnm 561968, 611816, 612616, 613738–613744, 614233–614235, 614771, 614772; G. australis greyi, uf 24326, 24327; G. a. australis, ypm 102249, 110760, 110789, 110790, 110844; G. philippensis good- soni, UF 39854, 39855; G. p. sethsmithi, uf 42902, 42933–42935; G. p. philippensis, usnm 560651; G. p. yorki, usnm 560791; G. p. mellori, usnm 620196; G. p. ecaudatus, uwbm 42863, 42865, 42866; G. [‘‘Nesoclopeus’’] wood- fordi, uf 39399, 39406, 39409, 39547, 39556, 39574; Gallinula chloropus, uf 39927; Porphyrio porphyrio samoensis, uf 39332, 39388, 39407, usnm 561547, 561549, 5461551; P. p. polioce- phalus, usnm 34212; P. p. pulverulentus, usnm 226035, 292296, 292297; Porphyrio martinicus, uf 42417, 42419; Porphyrio alleni, uf 34172, 38839. We also examined these fossil speci- mens: Gallirallus ripleyi humerus, uf 51402, ulnae, uf 54901, 55215, carpometacarpi, uf 54700, 54988, femur, uf 51320, tibiotarsi, uf 54732, 54985, usnm 402895 (holotype), tar- sometatarsi, uf 54761, 55223, usnm 402895 (holotype); G. vekamatolu humerus, uf 52333, ulna, uf 51734, femora, uf 52020, 52058, tibiotarsi, uf 51729, 52211, tarsometa- tarsus, uf 51991 (holotype); Porphyrio paepae femora, bpbm 165649, 166424, 166426, 166434, tibiotarsus, bpbm 165651, synsacrum, bpbm 165656. We follow Taylor (1998) for subspecies-level taxonomy. Measurements were taken with dial cali- pers ( Helios), rounded to the nearest 0.1 mm. To assess the degree of flightlessness in each species, we performed a principal com- ponents analysis (PCA) using the software package SPSS 13.0. Unweighted character means (natural [base e] log-transformed) for each species were used for the PCA. Charac- ters used in the PCA were chosen on the basis of availability in fossil specimens from Hua- hine. Osteological terminology follows Bau- mel and Witmer (1993). comparative osteology and systematics Family Rallidae Genus Gallirallus Lafresnaye, 1841 We regard all ‘‘typical long-billed rails’’ from Oceania as species of Gallirallus sensu lato, distinguishing them from the similarly sized swamphens (Porphyrio), moorhens (Gal- linula), and coots (Fulica), and the much smaller crakes (Porzana and Poliolimnas). This treatment departs slightly from the classifica- tion of Olson (1973a), who provisionally re- tained woodfordi of the Solomon Islands and poecilopterus of Fiji in the genus Nesoclopeus but highlighted their close affinity with Gal- lirallus. Livezey (1998, 2003) retained the genera Nesoclopeus, Tricholimnas, Cabalus, and Habropteryx for some species of long-billed rails but acknowledged the difficulty of es- tablishing generic-level relationships in this group on the basis of osteology. We refer 47 of the fossils from Huahine to Gallirallus rather than to other genera of Oceanic rails because of the following characters. Skull: frontals narrow, concave. Rostrum: long, narrow, and shallow with elongate nares. Hu- merus: fossa pneumotricipitalis deep and wide with prominent crus ventrale fossae. Ulna: thin in cranial aspect with rectangular (rather than rounded) margo cranialis. Pelvis: ala preacetabularis ilii broadly continuous with crista dorsalis of synsacrum. Femur: distal end of corpus femoris becomes gradually wider; condylus medialis subcircular in me- dial aspect; impresso ansae musculo iliofi- bularis abuts suclus fibularis. Tibiotarsus: impresso ligamentum collateralis medialis deep and wide; facies articularis femoris large; condylus medialis subcircular in medial as- pect. Tarsometatarsus: corpus tarsometatarsi much wider than deep; medial sulcus hypo- tarsi not enclosed; fossa metatarsi I short and shallow. 284 PACIFIC SCIENCE . April 2006 Gallirallus storrsolsoni Kirchman & Steadman, n. sp. Figures 3B; 4B; 5B,E,H,K holotype. Complete cranium and ros- trum, bpbm 166036 (Figure 3). paratypes. Crania, bpbm 166021, 166026, 168015, dapt 139; rostrum, dapt 21; vertebrae, bpbm 166024, 166025, 166035, 168001, 168002, 168078, dapt 13, 14, 25, 60, 61, 122, 143, 144, 145, 163; rib, bpbm 166018; sterna, bpbm 166017, 166027; humerus, bpbm 166022 (left [l]); ulnae, bpbm 166033 (l), 168121 (l), 168150 (right [r]); radius, bpbm 168056 (r); carpometacarpus, bpbm 168165 (l); synsacrum, bpbm 166020; femora, bpbm 168131 (r), dapt 27/105 (r); tibiotarsi, bpbm 166023 (l), 166032 (r), 168028 (l), 168046 (r), 168123 (r), 168149 (l), 168170 (l), dapt 47 (r), 55 (l), 119 (l); tarsometatarsi, bpbm 166034 (r), 168124 (r), dapt 7 (r). diagnosis. A medium-sized species of Gallirallus ( Table 1) distinguished from con- geners in Oceania as follows. Skull (Figure 3): fossa temporalis deeply excavated, clearly emarginated by crista temporalis and extends Figure 3. Lateral (left) and dorsal (right) views of the skulls of Gallirallus. A, G. philippensis, uwbm 42866. B, G. storrsolsoni, holotype, bpbm 166036. C, G. owstoni, uf 39918. D, G. torquatus, ummz 228275. E, G. woodfordi, uf 39399. Scale bars ¼ 50 mm. Fossil Rails from Huahine . Kirchman and Steadman 285 T A B L E 1 S k el et al M ea su re m en ts (i n m m ) in G al li ra ll u s, w it h M ea n , R an g e, an d S am p le S iz e. F , fe m al e; M , m al e; U , se x u n k n o w n . S p ec im en s o f al l av ai la b le su b sp ec ie s o f G . au st ra li s an d G . ph il ip pe n si s ar e co m b in ed , g iv en th at su b sp ec ifi c d if fe re n ce s in si ze ar e m u ch sm al le r th an si ze d if fe re n ce s b et w ee n m al es an d fe m al es . S k el et al E le m en t G . st or rs ol so n i G . ow st on i G . au st ra li s G . ri pl ey i G . v ek am at ol u G . ph il ip pe n si s G . st ri at u s G . to rq u at u s G . w oo df or di S ex U M F M F U U M F M M F M F C ra n iu m le n g th 3 3 .7 3 2 .4 – 3 4 .8 4 3 3 .3 3 2 .8 – 3 4 .2 4 3 1 .6 3 0 .9 – 3 2 .3 1 0 4 2 .9 4 2 .2 – 4 3 .5 2 4 0 .0 3 9 .0 – 4 1 .5 4 — — 3 2 .1 3 1 .0 – 3 2 .9 4 2 9 .9 2 8 .4 – 3 1 .0 6 2 8 .7 2 8 .2 – 2 9 .0 4 3 3 .9 3 2 .4 – 3 5 .2 5 3 1 .0 1 3 9 .8 3 9 .0 – 4 0 .5 3 3 9 .0 3 8 .2 – 3 9 .5 3 R o st ru m le n g th 3 8 .8 3 6 .5 – 4 1 .0 2 4 0 .7 3 6 .9 – 4 3 .3 6 3 7 .1 3 5 .5 – 3 9 .3 1 0 5 2 .0 5 0 .6 – 5 3 .3 2 4 6 .0 4 0 .0 – 5 0 .4 4 — — 3 6 .0 3 3 .5 – 3 8 .6 4 2 9 .5 2 7 .0 – 3 1 .6 6 3 5 .7 3 3 .0 – 3 8 .1 4 4 2 .2 3 9 .7 – 4 5 .8 4 3 9 .4 1 4 9 .1 4 7 .8 – 4 9 .9 3 4 4 .8 4 4 .6 – 4 5 .0 3 S te rn al ca ri n a d ep th 9 .1 1 1 0 .7 9 .7 – 1 1 .6 7 1 0 .4 9 .9 – 1 1 .4 1 0 1 2 .0 1 1 .5 – 1 2 .5 2 1 0 .6 9 .9 – 1 2 .0 4 — — 1 2 .7 1 2 .0 – 1 3 .5 6 1 2 .3 1 1 .6 – 1 3 .5 6 1 2 .2 1 1 .6 – 1 3 .0 3 1 3 .1 1 2 .2 – 1 4 .1 5 1 0 .9 1 1 3 .2 1 2 .6 – 1 3 .8 3 1 2 .6 1 2 .2 – 1 3 .4 3 S te rn u m w id th at co ra co id s 1 4 .6 1 4 .5 – 1 4 .8 2 1 1 .7 1 0 .7 – 1 2 .2 7 1 1 .3 9 .6 – 1 1 .9 9 2 0 .9 2 0 .3 – 2 1 .5 2 1 9 .2 1 8 .6 – 1 9 .9 4 — — 1 1 .1 9 .9 – 1 2 .0 6 1 0 .0 9 .4 – 1 0 .8 6 9 .0 8 .4 – 1 0 .0 4 1 1 .9 1 1 .1 – 1 2 .4 5 1 1 .7 1 1 8 .8 1 8 .6 – 1 9 .0 3 1 7 .7 1 6 .5 – 1 8 .8 3 H u m er u s sh af t w id th 2 .2 1 2 .8 2 .6 – 3 .1 7 2 .7 2 .6 – 3 .0 1 1 4 .3 3 .9 – 4 .6 3 3 .8 3 .5 – 4 .2 4 2 .1 1 — 3 .3 3 .2 – 3 .4 5 2 .9 2 .7 – 3 .3 6 2 .6 2 .5 – 2 .7 4 3 .2 3 .0 – 3 .4 5 2 .9 1 3 .8 3 .7 – 3 .8 3 3 .6 3 .5 – 3 .7 3 U ln a le n g th 3 7 .5 1 3 9 .1 3 6 .8 – 4 1 .5 7 3 6 .6 3 4 .8 – 3 8 .7 1 1 4 3 .7 4 3 .0 – 4 4 .2 3 3 8 .2 3 6 .0 – 4 1 .4 4 2 2 .9 2 2 .6 – 2 3 .1 2 4 1 .3 1 4 3 .9 4 1 .4 – 4 4 .8 6 3 9 .2 3 5 .2 – 4 3 .6 6 3 6 .2 3 3 .7 – 3 7 .9 4 4 4 .0 4 3 .0 – 4 5 .3 5 4 0 .0 1 5 1 .6 5 0 .7 – 5 2 .8 3 4 9 .5 4 7 .5 – 5 0 .6 3 U ln a p ro xi m al w id th 4 .8 1 4 .6 4 .3 – 4 .8 7 4 .3 4 .1 – 4 .5 1 1 7 .0 6 .5 – 7 .3 3 6 .0 5 .5 – 6 .8 4 2 .8 2 .7 – 2 .9 2 5 .4 1 5 .0 4 .7 – 5 .3 6 4 .3 4 .1 – 4 .4 6 4 .0 3 .8 – 4 .1 4 5 .1 4 .8 – 5 .4 5 5 .0 1 6 .4 6 .3 – 6 .5 3 5 .9 5 .9 – 6 .0 3 F em u r le n g th 4 9 .4 1 5 6 .0 5 4 .0 – 5 9 .2 7 5 2 .4 4 9 .2 – 5 4 .6 1 1 8 0 .6 7 8 .7 – 8 2 .3 3 6 9 .9 6 6 .1 – 7 3 .4 4 3 9 .8 1 — 5 3 .8 5 1 .3 – 5 4 .9 6 4 7 .3 4 5 .0 – 4 9 .7 6 4 5 .1 4 2 .2 – 4 6 .9 4 5 5 .5 5 3 .3 – 5 7 .5 5 5 0 .6 1 7 2 .1 7 2 .0 – 7 2 .3 3 6 9 .6 6 9 .0 – 7 0 .3 3 F em u r d is ta l w id th 9 .2 1 9 .5 8 .9 – 9 .9 7 8 .7 8 .4 – 9 .0 1 1 1 6 .5 1 5 .9 – 1 7 .6 3 1 4 .3 1 3 .2 – 1 5 .0 4 6 .7 1 1 0 .9 1 0 .7 – 1 1 .0 2 8 .7 8 .4 – 9 .1 6 7 .4 7 .0 – 7 .9 6 4 5 .1 4 2 .2 – 4 6 .9 4 9 .3 8 .6 – 9 .9 5 8 .5 1 1 3 .3 1 3 .2 – 1 3 .4 3 1 2 .7 1 2 .5 – 1 2 .9 3 T ib io ta rs u s le n g th 6 8 .6 1 7 9 .9 7 6 .1 – 8 4 .6 7 7 5 .5 7 2 .9 – 7 9 .8 1 1 1 1 7 .4 1 1 6 .6 – 1 1 8 .7 3 1 0 0 .0 9 3 .4 – 1 0 5 .0 4 — — 7 6 .9 7 1 .7 – 8 0 .3 6 6 6 .7 6 3 .0 – 7 0 .6 6 6 2 .1 5 8 .2 – 6 4 .3 4 8 4 .2 8 0 .9 – 8 7 .5 5 7 4 .6 1 1 0 5 .0 1 0 0 .6 – 1 0 8 .8 3 1 0 2 .8 9 9 .0 – 1 0 5 .8 3 T ib io ta rs u s d is ta l w id th 6 .9 1 7 .4 6 .8 – 7 .9 7 6 .8 6 .5 – 7 .1 1 1 1 2 .5 1 2 .1 – 1 3 .1 3 1 0 .8 1 0 .4 – 1 1 .2 4 6 .0 5 .6 – 6 .3 3 8 .0 7 .9 – 8 .0 2 6 .9 6 .5 – 7 .2 6 6 .1 5 .6 – 6 .7 6 5 .3 5 .1 – 5 .6 4 7 .2 6 .7 – 7 .6 5 6 .6 1 1 0 .0 9 .9 – 1 0 .1 3 9 .5 9 .4 – 9 .6 3 T ar so m et at ar su s p ro xi m al w id th 7 .4 1 7 .6 7 .0 – 8 .2 7 7 .0 6 .7 – 7 .3 1 1 1 2 .6 1 2 .2 – 1 3 .4 3 1 1 .0 1 0 .7 – 1 1 .7 4 5 .7 1 8 .3 7 .8 – 8 .7 2 7 .0 6 .7 – 7 .2 6 6 .1 5 .8 – 6 .6 6 5 .4 5 .3 – 5 .5 4 7 .4 7 .0 – 7 .9 5 6 .6 1 1 0 .5 1 0 .2 – 1 0 .7 3 1 0 .0 9 .9 – 1 0 .1 3 T ar so m et at ar su s sh af t w id th 4 .1 1 3 .8 3 .5 – 4 .0 7 3 .4 3 .2 – 3 .8 1 1 6 .1 5 .6 – 6 .4 3 5 .4 5 .2 – 5 .6 4 3 .0 2 .8 – 3 .1 2 4 .3 4 .0 – 4 .6 2 3 .5 3 .1 – 3 .6 6 3 .0 2 .8 – 3 .3 6 2 .7 2 .5 – 2 .9 4 3 .6 3 .3 – 3 .8 5 3 .3 1 4 .9 4 .8 – 5 .0 3 4 .6 4 .4 – 4 .7 3 T ar so m et at ar su s sh af t d ep th 2 .8 1 2 .8 2 .5 – 3 .0 7 2 .5 2 .4 – 2 .8 1 1 4 .8 4 .5 – 5 .0 3 4 .1 3 .8 – 4 .6 4 2 .2 2 .1 – 2 .3 2 3 .2 3 .0 – 3 .3 2 2 .8 2 .6 – 3 .0 6 2 .5 2 .3 – 2 .8 6 2 .1 2 .0 – 2 .2 4 2 .7 2 .2 – 2 .9 5 2 .6 1 4 .0 3 .9 – 4 .2 3 3 .8 3 .7 – 4 .0 3 more caudally; cranium with prominent crista nuchalis transversae and a low, broad calveria (as in G. woodfordi ); in dorsal aspect, the pos- terior margins of the orbits abruptly angle away from the midline; the lamina parasphe- noidalis is well emarginated caudally. Ster- num (Figure 4): spina externa of rostrum sterni absent. Humerus (Figure 5): incisura capitus narrows proximally in caudal aspect; crista deltopectoralis rectangular, parallel to corpus humeri; corpus humeri thin, round in cross-section. Ulna (Figure 5): corpus ulnaris straight and dorsoventrally flattened, more so than even in flightless G. owstoni, G. vekama- tolu, or G. australis; impressio brachialis deep and clearly emarginated. Synsacrum: broad in ventral aspect, gradually narrowing cau- dally. Femur (Figure 8): corpus femoris ro- bust, approaching but not surpassing the stoutness of G. vekamatolu. Tibiotarsus (Fig- ure 5): proportionally short (as in G. australis); incisura intercondylaris wide, resulting from an obtuse angle between the condylus medi- alis and condylus lateralis; juncture of condy- lus medialis with facies caudalis of corpus tibiotarsis abrupt rather than gradually slop- ing. Tarsometatarsus (Figure 5): corpus tar- sometatarsi dorsoventrally flattened with a width-to-depth ratio (1.46) greater than in other species (1.21–1.36); viewed medially, the proximal one-third of corpus tarsometa- tarsi slopes toward the hypotarsus rather than being perpendicular to facies dorsalis. etymology. Named after Storrs L. Ol- son in recognition of his unparalleled con- tributions to the evolution, systematics, and paleontology of flightless rails on islands. remarks. Gallirallus storrsolsoni is a medium-sized species that, in overall size, resembles G. owstoni, G. philippensis, G. stria- tus, and G. torquatus. It is larger than G. ripleyi and smaller than G. australis, G. vekamatolu, Figure 4. Ventral (left) and lateral (right) views of the sterna of Gallirallus. A, G. owstoni, uf 39918. B, G. storrsolsoni, bpbm 166027. C, G. philippensis, uwbm 42866. Scale bars ¼ 50 mm. Fossil Rails from Huahine . Kirchman and Steadman 287 Figure 5. Humeri (A–C ), ulnae (D–F ), carpometacarpi (G–I ), tibiotarsi ( J–L), and tarsometatarsi (M–O) of Galliral- lus philippensis (A, D, G, J, M, all from uf 39855), G. storrsolsoni (B, bpbm 166022; E, bpbm 166033; H, bpbm 168165; K, bpbm 166023; N, dapt 7), and G. owstoni (C, F, I, L, O, all from uf 42968). Scale bar ¼ 50 mm. and G. woodfordi. Gallirallus storrsolsoni has a greatly reduced carina sterni, small wing ele- ments, and stout leg elements as in its flight- less congeners. The diagnosis of flightlessness is supported by morphometric comparisons with species of Gallirallus that are known to be either volant or flightless. Correlation coefficients of the first four principal com- ponents (PC), which together account for 99.4% of morphological variance, indicate that PC 1 describes variation in overall size and the degree of reduction of the carina sterni, ulna, and carpometacarpus, and that PC 2 is a description of keel and wing reduc- tion, and leg-bone robustness ( Table 2). A plot of PC 1 versus PC 2, summarizing 96.5% of morphometric variance, clusters G. storrsolsoni with flightless rather than volant congeners (Figure 6). The material from Fa‘ahia represents six individuals, minimally. Because of the excel- lent preservational environment at the Fa‘a- hia site, even the most delicate elements of the skeleton of G. storrsolsoni are known, in- cluding one partial sternum (uf 166027) that still retains the anterior margin of the carina. Outside the New Zealand region, such pres- ervation is unique; all other Gallirallus species described from fossils, G. ripleyi (Mangaia, Cook Islands), G. huiatua ( Niue), and G. vekamatolu (‘Eua, Tonga), were considered to be flightless on the basis of limb-bone pro- portions (Steadman 1987, Steadman et al. 2000, Kirchman and Steadman 2005). Genus Porphyrio Brisson, 1760 We refer three femora from the Fa‘ahia archaeological site (bpbm 166031, dapt 39, 53) to Porphyrio rather than the other genera of large Pacific rails (Gallirallus, Gallinula, Fulica) because of these characters: in proxi- mal aspect, more obtuse angle formed at the junction of the impressiones obturatoriae and trochanter femoris; impressiones obtura- toriae more prominent, leading to a more concave proximoposterior area of corpus femoris; similar size and position of the im- pressiones iliotrochanteria and linea inter- muscularis caudalis; corpus femoris overall more slender; distal end of corpus femoris not expanded laterally until the epicondylus lateralis is reached; rotular groove more nar- row; in posterior aspect, medial margin of TABLE 2 Principal Components Analysis Correlation Coefficients of 16 Skeletal Measurements from Eight Species of Gallirallus (See Text, Figure 6) Correlation Coefficients Skeletal Element PC1 PC2 PC3 PC4 Sternum, width at coracoids .265 �.093 �.045 .019 Sternum, keel depth .097 .177 .037 .027 Humerus, shaft width .219 .089 .077 �.014 Ulna, total length .146 .110 �.035 .003 Ulna, proximal width .217 .024 �.013 .023 Ulna, shaft width .203 .049 .025 .030 Carpometacarpus, intermetacarpal space length .163 .165 �.098 �.022 Femur, total length .224 .021 .021 �.002 Femur, distal width .293 �.047 .004 �.002 Femur, shaft width .255 �.024 �.002 .015 Tibiotarsus, total length .222 .014 .023 �.031 Tibiotarsus, distal width .263 �.048 .018 �.011 Tibiotarsus, shaft width .263 �.012 .002 �.030 Tarsometatarsus, proximal width .258 �.061 .004 �.013 Tarsometatarsus, shaft width .253 �.067 �.029 .018 Tarsometatarsus, shaft depth .262 �.037 .004 .004 Percentage total variance explained 85.81 10.65 2.33 0.61 Fossil Rails from Huahine . Kirchman and Steadman 289 the condylus medialis oriented roughly paral- lel to the shaft rather than diagonal. Porphyrio mcnabi Kirchman & Steadman, n. sp. Figures 7A, 8D holotype. Nearly complete right femur, bpbm 166031 (Figures 7, 8). paratypes. Distal left femur, dapt 53. Left femur lacking distal end, dapt 39. diagnosis. A small species of Porphyrio ( Table 3) distinguished from congeners as follows: impressiones iliotrochanteris extends farther (more distad) along corpus femoris than in P. paepae; in lateral aspect, corpus femoris straighter than in all but P. paepae; in lateral aspect, crista trochanteris more rounded (less flared) on dorsal surface than in P. paepae; most proximal section of linea intermuscularis caudalis (¼ dorsalis) weakly developed (thicker and more protrudent in P. paepae). etymology. Named after Brian K. McNab in recognition of his important re- search on the evolution and physiological ecology of flightless birds, especially rails, on oceanic islands. Figure 6. Plot of mean scores for eight species of Gallirallus on the first two principal components (summarizing 96.5% of variance) of 16 postcranial skeletal measurements. Hollow symbols are volant species; filled symbols are flightless species. The line indicates a hypothesized threshold for flightlessness. —————————————————————————————————————————————————f Figure 7. Cranial (upper) and caudal (lower) views of femora of Porphyrio. A, P. mcnabi, holotype, bpbm 166031. B, P. paepae, bpbm 165649. C, P. martinicus, uf 42419. D, P. porphyrio, uf 39407. Scale bars ¼ 50 mm. 290 PACIFIC SCIENCE . April 2006 Figure 8. Femora of Gallirallus and Porphyrio in cranial aspect. A, G. philippensis, uf 39855. B, G. storrsolsoni, dapt 27/105. C, P. martinicus, uf 42419. D, P. mcnabi, bpbm 166031. Scale bar ¼ 50 mm. TABLE 3 Selected Skeletal Measurements (in mm) of the Femur in Porphyrio with Mean, Range, and Sample Size. F, female; M, male; U, sex unknown. Femur P. mcnabi P. paepae P. porphyrio samoensis P. [porphyrio] pulverulentus P. [porphyrio] poliocephalus P. martinicus P. alleni Sex F? U M F M F M M F M F Total length 49.4 1 52.1 51.7–52.5 2 81.3 76.4–86.5 3 70.0 64.7–72.8 3 78.2 77.9–78.4 2 75.4 1 68.8 1 53.8 52.0–55.4 5 50.7 47.7–52.4 6 46.1 1 44.7 1 Shaft width 3.9 1 4.1 3.9–4.2 3 5.9 5.6–6.1 3 5.0 4.5–5.4 3 5.2 5.1–5.3 2 5.1 1 4.8 1 3.6 3.3–3.7 6 3.4 3.2–3.6 6 3.0 1 2.9 1 Distal width 9.2 1 9.5 9.5–9.5 2 13.7 13.0–14.8 3 12.4 10.9–13.8 2 13.8 13.4–14.2 2 13.4 1 11.7 1 8.5 8.1–8.7 6 7.9 7.4–8.8 6 7.0 1 6.4 1 Note: Some measurements of P. porphyrio and P. martinicus are from Steadman (1988). remarks. Porphyrio mcnabi is a small spe- cies that, in overall body size, resembles P. paepae and P. martinicus. It is larger than P. flavirostris and P. alleni and is exceeded in size by P. porphyrio, P. mantelli, P. hochstetteri, P. kukwiedii, and Porphyrio undescribed spe- cies A and B (see later in this section). The three femora of P. mcnabi were among the 50 bones listed as ‘‘Gallirallus new sp.’’ in Steadman and Pahlavan (1992). It is likely that bpbm 166031 represents an adult female (smaller), whereas dapt 39 (left) and dapt 53 (right) represent a single juvenile male (larger). That dapt 39 and 52 are from a ju- venile is supported by their porous surfaces, thin-walled shafts, and being slightly more gracile than would be expected in an adult. Lacking elements of the wing or pecto- ral girdle, we cannot say whether Porphyrio mcnabi was flightless. The extant P. martini- cus, P. flavirostris, P. alleni (all small), and P. porphyrio (large) are all volant. The four very large, extinct species (P. kukwiedii of New Caledonia, P. mantelli of New Zealand, Por- phyrio undescribed species A of New Ireland, Bismarck Archipelago, and Porphyrio unde- scribed species B of Buka, Solomon Islands) all were flightless, as is the very large, extant P. hochstetteri of New Zealand (Balouet and Olson 1989, Worthy and Holdaway 2002, Steadman in press). The small, extinct P. pae- pae of the Marquesas had somewhat reduced wings but perhaps was still volant (Steadman 1988). discussion Flightlessness Rails are developmentally predisposed to become flightless (Olson 1973b, Feduccia 2000), and scores of neotenic flightless spe- cies have evolved independently on oceanic islands that lack indigenous placental carni- vores. The hypothesis that flightlessness evolves as a means of energy conservation is supported by the basal metabolic rates in flightless species of insular rails being lower than those of their volant relatives (McNab 1994a,b). This finding, coupled with the ob- servation that metabolic rate also correlates positively with relative pectoral muscle mass (McNab 1994a, 2002), suggests that selection for reduced pectoral and wing musculature is the likely cause of insular avian flightlessness. Skeletons of flightless rails are distin- guished from those of volant relatives by hav- ing reduced sternal keels (carina sterni) and shorter, thinner wing bones. Livezey (1998, 2003) has shown that the degree of reduc- tion of pectoral elements varies greatly even among flightless species. Indeed there appears to be a continuum of wing reduction among flightless rails that mirrors the graded reduc- tion in energy expenditure (McNab 2002). Our morphometric analysis of Gallirallus skeletons indicates that some species, such as G. australis, have greatly reduced carina sterni and wing elements, whereas other extant spe- cies known to be flightless, such as G. owstoni, seem to be near the threshold of flight. Biogeography Of the G18 living and extinct species of Gal- lirallus sensu lato that have been named, all but two are flightless species endemic to Oce- ania on single islands or on multiple islands that were connected during the late Pleisto- cene period of lowered sea levels (Steadman 1987, in press, Diamond 1991, Mayr and Di- amond 2001). The two extant, volant species, G. torquatus and G. philippensis, are sympatric in the Philippines, Sulawesi, and New Guinea, although the latter species is very widespread, its distribution extending south to Australia and New Zealand and east in Oceania to Samoa. Flightless species of Gallirallus have evolved on nearly all major archipelagos in Oceania from the Ryukyu Islands of southern Japan, south to New Zealand’s Chatham Islands, and east to the Society Islands. Bones (still undescribed) of Gallirallus also have been found in archaeological sites on four islands in the Marquesas (Steadman 1989a, Steadman and Rolett 1996). Gallirallus ap- parently never made it as far northeast in Oceania as the Hawaiian Islands or as far southeast in Polynesia as Henderson Island, both of which have good Holocene fossil bird records ( James and Olson 1991, Olson and James 1991, Wragg 1995, Steadman in press). Fossil Rails from Huahine . Kirchman and Steadman 293 Gallirallus storrsolsoni is not the only species of flightless rail known from the Society Is- lands. The extinct G. pacificus was discovered on Tahiti by naturalists from Captain James Cook’s second voyage (1777), but no speci- mens exist, and the species is known only from a painting by Georg Forster. The plum- age, soft-part colors, and bill shape make it clear that pacificus is correctly accomodated in Gallirallus. Measurements made by Storrs L. Olson in 1998 ( pers. comm.) from For- ster’s original, full-scale painting in the Brit- ish Museum of Natural History indicate that G. pacificus was a much smaller rail than G. storrsolsoni. For example, the culmen (with epidermal sheath) in G. pacificus is 28.8 mm, whereas the rostrum (without epidermal sheath) in G. storrsolsoni is 36.5–41.0 mm ( Table 1). The tarsus (incuding scutes) in G. pacificus is 33.8 mm, whereas the tarsometa- tarsus (without epidermal sheath) in G. storrs- olsoni is ca. 48.5 mm, based on a composite of two incomplete specimens (dapt 7, bpbm 166034). Gallirallus pacificus is presumed to be flightless on the basis of the short wings in the painting; although this is likely, in the absence of specimens it cannot be verified in the painting. The possible former existence of G. pacificus on Mehetia ( Taylor 1998), a small island 110 km east-southeast of Tahiti, is unsubstantiated and doubtful. Based on its geological and geographical setting, any flightless species on Huahine is likely to have been endemic to the island. The geological age of Huahine is ca. 3 mil- lion yr (Dickinson 1998). It is an eroded vol- canic island surrounded by a broad fringing reef, outside of which the water becomes very deep. The nearest island is Ra‘iatea, ca. 35 km to the west. Huahine never was con- nected to any other island, even during the lowered sea levels of Pleistocene glacial inter- vals, when Ra‘iatea still would have been ca. 30 km away. The genus Porphyrio is widespread in trop- ical and subtropical lowlands. Two extant, volant species, P. martinicus and P. flavirostris, are confined to the Americas. All other spe- cies are from the Old World, with extant, vo- lant P. alleni in Africa and the larger, extant, volant P. porphyrio very widespread from southern Europe and Africa eastward across southern Asia, Indonesia, and Australia to Oceania as far east as Fiji, Tonga, Samoa, and Niue ( Taylor 1998:464, 465). No species of Porphyrio inhabit East Polynesia today. The radiation of certainly or presumably flightless species of Porphyrio is confined to Oceania (Balouet and Olson 1989, Worthy and Holdaway 2002, Steadman in press). The only flightless species that still exists is P. hochstetteri from South Island, New Zea- land. Known extinct forms of Porphyrio are P. mantelli ( North Island, New Zealand), P. albus (Lord Howe Island), P. kukwiedii ( New Caledonia), and Porphyrio undescribed sp. A ( New Ireland) and sp. B (Buka, Solomon Is- lands). Each of these species was as large as or larger than the massive P. hochstetteri, which is the largest extant form. Finally, Porphyrio paepae was a smaller, probably flightless swamphen that is known from Hiva Oa and Tahuata, two islands only 3 km from each other in the Marquesas (Steadman 1988). At the time of its descrip- tion, P. paepae was the only species of Por- phyrio known from East Polynesia. The discovery of P. mcnabi in the Society Islands helps to bridge the formerly huge distribu- tional gap of the genus (from Niue to the Marquesas) and strengthens the likelihood that a substantial radiation of swamphens once existed in East Polynesia. At this point, we cannot say whether this radiation was of Old World or New World origin. Osteologi- cal synapomorphies that ally P. paepae and P. mcnabi with either the New World species (P. martinicus, P. flavirostris) or the Old World P. porphyrio s.l. have not been discerned. Given the propensity in P. martinicus and P. flavirostris for unpredictable, long-distance dispersal (Remsen and Parker 1990), the geo- graphic origin of East Polynesian Porphyrio species remains an open question. Avian Extinction on Huahine The Fa‘ahia archaeological site contained the bones of 15 resident species of seabirds, three migratory species of shorebirds, and 16 spe- cies of resident land birds (Steadman and Pahlavan 1992, Steadman in press). Of the 294 PACIFIC SCIENCE . April 2006 15 seabirds, 12 no longer occur on Huahine, including the extinct gull Larus utunui (Stead- man 2002). The other 11 species of seabirds still are found, at least locally, elsewhere in Oceania. Each of the migratory shorebirds, on the other hand, may visit Huahine season- ally today. Of the 16 species of land birds from Fa‘ahia, 13 no longer occur on Hua- hine. They consist of the locally extripated heron Butorides (Ardeola) striatus, rail Porzana tabuensis, dove Gallicolumba erythroptera, pi- geons Ducula galeata and D. aurorae, and war- bler Acrocephalus caffer. Aside from Gallirallus storrsolsoni and Porphyrio mcnabi, the extinct species of land birds from Fa‘ahia include the doves Gallicolumba nui and Macropygia arevarevauupa, lorikeets Vini vidivici and V. si- notoi, and starling Aplonis diluvialis (Steadman and Zarriello 1987, Steadman 1989b, 1992). The survivors are the very widespread heron Egretta sacra and two species endemic to the Society Islands, the dove Ptilinopus pur- puratus and kingfisher Halcyon tuta. Also ex- tant on Huahine is the very widespread duck Anas superciliosa, which was not found among the bird bones from Fa‘ahia. Two additional species of land birds, the lorikeet Vini peruvi- ana and swiftlet Collocalia leucophaea, are un- known at the Fa‘ahia site but were recorded from Huahine in the nineteenth century, al- though they no longer persist on the island (Steadman in press). Altogether, 19 species of land birds have been recorded from Hua- hine, which is the same number that is known from much-larger Tahiti, which has no fossil record of birds. 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