Gallirallus pendiculentus, Kirchman, Jeremy J. & Steadman, David W., 2006

Kirchman, Jeremy J. & Steadman, David W., 2006, Rails (Rallidae: Gallirallus) from prehistoric archaeological sites in Western Oceania, Zootaxa 1316, pp. 1-31 : 18-21

† Gallirallus pendiculentus new species

Holotype: Complete humerus UF 63419 ( Figure 4 A), Unai Chulu archaeological site, Tinian, Commonwealth of the Northern Mariana Islands.

Paratypes: Bones from two archaeological sites on Tinian are referred to G. pendiculentus . From Unai Chulu (complete bones underlined): Rostra UF 62140, 62300, 62301, 63385, 63462. Quadrates UF 63393, 63468, 63516, 63552. Mandibles UF 62378, 62664, 62665, 63366, 63447, 63495, 63559. Vertebra UF 63440. Sterna UF 62295, 62320, 62334, 62354, 62377, 62387, 62669, 63432. Scapulae UF 62091–62094, 62164, 62319, 62353, 62391, 62634, 62683, 63388, 63433, 63459, 63467, 63473, 63494, 63515, 63546, 63547. Coracoids UF 61942, 61951, 61974, 62009, 62022, 62046–62048, 62078, 62124, 62160, 62167, 62198, 62227, 62307, 62313, 62359–62361, 62380, 62393, 62425, 62431, 62635, 62675, 62687, 63361, 63368, 63386, 63387, 63402, 63423, 63430, 63503, 63504, 63600, 63601, 63617, 63618, 63696. Humeri UF 61905, 61908, 61915, 61952, 62003, 62008, 62015, 62024, 62036, 62037, 62081, 62090, 62117, 62126–62128, 62133, 62146, 62179–62182, 62262, 62263, 62335, 62365, 62374, 62381, 62383, 62413, 62439, 62441,62636–62638, 62639, 62759, 62765, 63367, 63370, 63383, 63392, 63398, 63412, 63426, 63498–63503, 63522, 63523, 63529, 63534, 63543–63545, 63553, 63557, 63570, 63580, 63585,63591, 63598, 53599, 63610, 63614–63616, 63644, 63645, 63673, 63674, 63694, 63695. Ulnae UF 61907, 61916, 61917, 61945, 62209, 62312, 62414, 62264, 62265, 63375, 63404, 63429 ( Figure 4 D), 63521, 63530, 63548, 63556. Radii UF 62088, 62089, 62171, 62616, 62666, 63456,63549, 63612, 63646, 63708. Carpometacarpi UF 61939, 61941, 62049, 62050, 62095, 62134, 62135, 62150, 62199, 62366, 62394, 62415, 62416, 62424, 62432, 62274, 62275, 62668, 62711, 63372 ( Figure 2 C), 63384, 63442, 63480, 63481, 63588, 63594, 63609, 63641–63643,63676–63678. Phalanx 1 of digitus majoris UF 62384. Pelvis UF 63452. Femora UF 61894, 61904, 61922, 61934, 61972, 61975, 61976, 62016, 62020, 62031, 62043, 62080, 62168, 62178, 62228, 62294, 62327, 62331, 62332, 62350, 62358, 62376, 62389, 62619, 62682, 62715, 62746, 62761, 62769, 62775, 63357, 63362, 63369, 63376, 63377, 63380, 63400, 63431, 63443, 63448, 63451, 63463, 63466, 63469, 63472, 63475, 63490–63493, 63511, 63517, 63518, 63525, 63528, 63531, 63541, 63560, 63592, 63613, 63647–63651, 63700. Tibiotarsus UF 61896–61899, 61902, 61903, 61909, 61910, 61913, 61914, 61920, 61938, 61947, 61963/61964 (two pieces glued together), 61977, 61988, 61992, 61997, 61998, 62002, 62005, 62006, 62010, 62014, 62018, 62019, 62023, 62025, 62027–62030, 62032–62034, 62038–62042, 62051–62054, 62056, 62057, 62059–62061, 62082–62087, 62112–62016, 62130–62132, 62141–62145, 62151, 62153, 62156, 62157, 62161–62163, 62169, 62170, 62184–62186, 62188, 62196, 62197, 62201–62208, 62229–62232, 62255–62261, 62291, 62311, 62315–62317, 62328–62330, 62349, 62356, 62357, 62367, 62369, 62379, 62382, 62392, 62400, 62401, 62410–62412, 62428, 62429, 62437, 62438, 62502, 62600, 62633, 62655–62663, 62701, 62703, 62704, 62712, 62716, 62717, 62720, 62737, 62763, 62764, 62771, 62772, 62777, 62779, 63358, 63359, 63363, 63371, 63374, 63378, 63379, 63382, 63389, 63399, 63405–63410, 63413–63416, 63420, 63427, 63434, 63435, 63438, 63439, 63444, 63446, 63449, 63464, 63465, 63471, 63482–63485, 63488, 63489, 63504–63510, 63512, 63519, 63524, 63538–63540, 63550, 63551, 63561–63569, 63577–63579, 63586, 63587, 64595–63597, 63608, 63619–63626, 63652–63658, 63679–63682, 63691, 63692, 63695. Tarsometatarsus UF 61895, 61901, 61921, 61944, 61999, 62001, 62007, 62017, 62026, 62035, 62044, 62045, 62058, 62077, 62079, 62120–62123, 62125, 62147–62149, 62152, 62154, 62158, 62159, 62165, 62166, 62172–62177, 62187, 62195, 62210–62217, 62219, 62233–62237, 62266–62272, 62308–62310, 62314, 62336–62340, 62346–62348, 62355, 62362–62364, 62386, 62370, 62375, 62386, 62390, 62399, 62423, 62430, 62436, 62617, 62648–62654, 62686, 62729, 62753, 62756–62758, 62766, 62773, 63360, 63364, 63365, 63381, 63391, 63411, 63421, 63425, 63428, 63436, 63453, 63460, 63461, 63470 ( Figure 5 B), 63477–63479, 63496, 63497, 63513, 63514, 63532, 63533, 63571–63573, 63576, 63589, 63590, 63593, 63627 ( Figure 5 A), 63628–63633, 63659–63663, 63683. Pedal phalanges UF 61923, 61924, 61928, 61933, 61937, 61956–61958, 61970, 61971, 61978–61981, 61986, 61987, 61991, 62013, 62055, 62062–62076, 62100–62110, 62129, 62136–62139, 62155, 62188–62193, 62220–62226, 62238–62254, 62276–62290, 62302–62305, 62318, 62341–62345, 62351, 62352, 62371–62373, 62395–62398, 62402–62404, 62417–62422, 62426, 62427, 62433–62435, 62608, 62611–62613, 62632, 62640–62647, 62691, 62692, 62695, 62697, 62739, 62747, 62450, 62455, 62474, 62762, 63373, 62778, 63394–63397, 63401, 63403, 63417, 63437, 63441, 63520, 63535–63537, 63575, 63581, 63602–63605, 63611, 63634–63640, 63664–63673, 63684–63689, 63690, 63476.

From Railhunter Rockshelter: Rostra UF 60023, 60027, 60042, 60044, 60071, 60147, 60143, 60148, 60199. Mandibles UF 60027, 60108, 60129, 60147, 60148, 60198, 60210. Vertebra UF 60209. Sterna UF 60072, 60109, 60142 ( Figure 4 B), 60149, 60166. Coracoids UF 60042, 60045, 60058, 60078, 60130, 60143, 60178, 60110 ( Figure 2 C), 60111, 60217, 60219, 60225, 60226. Scapulae UF 60029, 60030, 60059, 60073–60077, 60112, 60146, 60150, 60179, 60180, 60188–60190, 60224. Humeri UF 60046, 60079–60081, 60131, 60151, 60167, 60181, 60191, 60212. Ulnae UF 60083, 60084, 60185. Radii UF 60113, 60132, 60133, 60152, 60192. Carpometacarpi UF 60085, 60060. Pelvis UF 60086. Femora UF 60049, 60061, 60134–60137, 60153, 60157, 60168, 60177, 60182, 60193 ( Figure 5 A), 60194, 60158, 60114, 60115/60116 ( Figure 5 B, two pieces glued together). Tibiotarsi UF 60031, 60032, 60047, 60048, 60050, 60051, 60062–60066, 60087–60096, 60117–60119, 60126–60128, 60138, 60175, 60186, 60200–60203, 60207, 60213, 60220, 60227. Fibulae UF 60154, 60195. Tarsometatarsi UF 60033–60035, 60052, 60067, 60097–60102, 60139, 60144, 60145, 60155, 60156, 60159–60161, 60169–60172, 60176, 60187, 60196, 60214, 60215. Pedal phalanges UF 60036–60041, 60082, 60103–60107, 60120–60125, 60140, 60141, 60162–60165, 60173, 60174, 60183, 60197, 60204–60206, 60208, 60216, 60218, 60220, 60221.

Diagnosis. A medium­sized rail, slightly smaller than Gallirallus philippensis ( Table 3), and with disproportionately shorter wing elements. Elements of the pectoral girdle and wing distinguish † G. pendiculentus from all other known species of Gallirallus , as follows. Sternum: spina externa of rostrum sterni absent; margo cranialis of carina sterni shifted dorsally and caudally relative to volant congeners; margo cranialis of labrum dorsale deeply notched (<90°) to form a v­shaped medial separation between the sulci articularis coracoidei. Coracoid: corpus coracoidei stout, relatively short ( Table 3); humero­ventral half of corpus coracoidei wide, with much protrudence of facies articularis clavicularis; lateral margin of facies articularis humeralis short, rounded in humeral aspect. Humerus: short relative to leg elements; distal end wide relative to length and width of corpus humeri ( Table 3); as in the flightless species G. owstoni , G. australis , and † G. ripleyi , the corpus humeralis with a straight margo cranialis (rather than sigmoid) in dorsal aspect; crista bicipitalis reduced distally; distal margin of crista pectoralis slopes more gradually to corpus humeri; fossa musculo brachialis deep; processus supracondylaris dorsalis large. Ulna: similar in size and proportion to G. striatus and small female G. philippensis ; depressio musculo brachialis relatively deep and more distinctly emarginated than in G. philippensis , G. torquatus , G. striatus , G. o w s t o n i, or G. australis , resembling the condition seen in † G. r i p l e y i and † G. storrsolsoni , the latter having the deepest, most prominent depressio musculo brachialis; tuberculum carpale juts abruptly out from corpus ulnare (rather than gradually sloping to corpus ulnare) and is triangular rather than circular in ventral aspect. Carpometacarpus: shorter but not more slender than in female G. philippensis , but less shortened than in G. owstoni . Femur and tibiotarsus: not smaller than ( Table 2) or qualitatively different from G. philippensis . Tarsometarsus: slightly more robust (shorter on average but not wider) than in G. philippensis ; trochlea metatarsi III relatively wide in dorsal aspect.

Etymology. Derived from the Latin word pendiculus, meaning a noose or snare ( Brown 1956: 812). The name pendiculentus is an adjective (“of the snare”) modifying the masculine Latin noun Gallirallus . It refers to the manner by which we believe the remains of this flightless species were accumulated, that is by hunters using leg­hold snares.

Remarks. The first and second components identified by our PCA of 17 post­cranial skeletal characters (Table 5) summarize 89.42% and 8.08% of morphological variance, respectively. Each of the subsequent components accounts for less than 1% of the variance. Correlation coefficients ( Table 4 ) indicate that the first component describes the overall body size of each species, whereas the second component describes the degree of flightlessness, with high positive values corresponding to reduced length of wing elements and high negative values corresponding to robust (wide) leg elements. Mean values of species plotted along these axes ( Figure 6 ) separate known flightless species from known volant ones. The position of † G. pendiculentus lies on or just above the threshold for flightlessness, suggesting that it was likely to have been flightless.

Sternal characters associated with flightlessess indicate that † G. pendiculentus had reduced flight capability relative to the three similarly sized, volant species ( G. philippensis , G. striatus , and G. torquatus ), but a stronger degree of volancy than in the fully flightless species G. owstoni , † G. w a k e n s i s, G. woodfordi , or especially G. australis . The apex of the carina sterni is not preserved in any specimen of † G. pendiculentus , precluding measurement of carina depth. Nevertheless, the condition of the sternum corroborates the hypothesis that † G. pendiculentus was near the threshold of flightlessness on the basis of PCA of other postcranial elements ( Figure 6 ).

Figures

FIGURE 2. The coracoids (upper row) and carpometacarpi (lower row) of Gallirallus rails from the Mariana Islands. A. † G. pisonii new species, UF 62934, UF 62917, Aguiguan. B. † G. temptatus new species, UF 63302, UF 63299, Rota. C. † G. pendiculentus new species, UF 60110, UF 63372, Tinian. D. G. owstoni male, UF 39921, Guam. E. G. philippensis male, UF 39855, Tutuila, American Samoa. Scale = 30 mm.

FIGURE 4. Wing elements of Gallirallus, including posterior (upper row) and anterior (lower row) aspects of the humerus (A – C), and ventral (upper row) and dorsal (lower row) aspects of the ulna (D – F). Shown are † G. pendiculentus new species, Tinian (A, UF 63419; D, UF 63429), G. owstoni male, Guam (B, E, UF 39920), and G. philippensis male, Tutuila, American Samoa (C, F, UF 39855). Scale = 40 mm.

FIGURE 5. Size variation in the femur (top row) and tarsometatarsus (bottom row) of † Gallirallus pendiculentus (A, UF 60193, UF 63627 [field no. 1024 C); B, UF 60115 / 60116, UF 63470; all sex unknown, Tinian, Mariana Islands), G. owstoni (C, female UF 39220; D, male UF 39221, both from Guam, Mariana Islands), and G. philippensis (E, female UF 43222, Efate, Vanuatu; F, male UF 39855, Tutuila, American Samoa). Scale = 40 mm.

FIGURE 6. Principal components analysis of 17 post­cranial skeletal measurements (summarized in Table 4) in species of Gallirallus, plotting the first two principal components (PC 1, PC 2). Solid symbols are flightless species; hollow symbols are volant species. † Gallirallus pendiculentus appears to be near the threshold of flightlessness.