Tongoenas burleyi gen. et sp. nov. (1 Viewer)

[albertonykus]

Steadman, D.W. and O.M. Takano (2020)
A new genus and species of pigeon (Aves, Columbidae) from the Kingdom of Tonga, with an evaluation of hindlimb osteology of columbids from Oceania
Zootaxa 4810: 401-420
doi: 10.11646/zootaxa.4810.3.1
https://www.biotaxa.org/Zootaxa/article/view/zootaxa.4810.3.1

The region from New Guinea through Oceania sustains the world’s most diverse set of columbids. We describe osteological characters of the hindlimb (femur, tibiotarsus, tarsometatarsus) that divide the Papuan-Oceanic pigeons and doves into three groups based on functional morphology: “arboreal” (Hemiphaga, Ducula, Ptilinopus, Drepanoptila, Gymnophaps), “intermediate” (Columba, Macropygia, Reinwardtoena), and “terrestrial” (Gallicolumba [includes Alopecoenas], Trugon, Microgoura, Goura, Chalcophaps, Geopelia, Henicophaps, Caloenas, Didunculus, Otidiphaps). The arboreal and terrestrial groups are each distinctive osteologically, especially in the tibiotarsus and tarsometatarsus, which are short relative to the femur in the arboreal group, and long relative to the femur in the terrestrial group. The intermediate pigeons are more similar to arboreal than to terrestrial pigeons, but nonetheless fit in neither group. To estimate the phylogenetic relationships among or within these three groups is somewhat tentative using hindlimb osteology alone, although all five genera of arboreal pigeons have independent molecular evidence of relatedness, as do most of the genera of terrestrial pigeons.

Using the hindlimb and other osteological data as a framework, we describe a new extinct genus and species of pigeon, Tongoenas burleyi, from Holocene archaeological and Pleistocene paleontological sites on six islands (Foa, Lifuka, `Uiha, Ha`afeva, Tongatapu, and `Eua) in the Kingdom of Tonga. Tongoenas was a large-sized member of the “arboreal” pigeon group, with osteological characters that relate it to Ducula, Gymnophaps, and Hemiphaga (generally canopy frugivores) rather than with the “terrestrial” pigeons (more ground-dwelling and granivorous) such as Gallicolumba, Trugon, Microgoura, Goura, etc. (others listed above). Among volant columbids, living or extinct, only the species of Goura (from New Guinea) are larger than Tongoenas. From most of the same prehistoric sites, we also report new material of the nearly as large, extinct pigeon Ducula shutleri Worthy & Burley, recently described from islands in the Vava`u Group of Tonga. Thus, D. shutleri also was widespread in Tonga before human impact. The prehistoric anthropogenic loss in Tonga of Tongoenas burleyi, Ducula shutleri, and other columbids undoubtedly had a negative impact on the dispersal regimes of Tongan forest trees. At first human contact about 2850 years ago, at least nine species of columbids in six genera inhabited the Tongan islands, where only four species in three genera exist today.

 

[Fred Ruhe]

Systematic Paleontology

Order Columbiformes
Family Columbidae
Tongoenas burleyi new genus and species

Holotype. UF 159857, tarsometatarsus (Figs. 3, 4; Table 2), Ha`ateiho site, Tongatapu, Tonga. Collected by D. V. Burley, D. W. Steadman, A. Barton, J. I. Mead, and S. Swift on 6 August 1999.
Paratypes. All from the Ha`ateiho site, Tongatapu, Tonga: femora UF 159536, 159772; tibiotarsi UF 159853 (Fig. 5, Table 2), UF 159854–159856; tarsometatarsus, hallux, and pedal phalanges UF 159858–159883, associated with the holotype UF 159857; tarsometatarsi UF 159469 (Figs. 3, 4, Table 2), UF
159648, 159659, 159660 (Figs. 3, 4, Table 2), UF 160604; pedal phalanx UF 159783. Casts of the type series will be made for distribution to other institutions, including the Archaeological Collections of Simon Fraser University, Burnaby, B.C., where much of the Tongan zooarchaeological material resides.
Referred Material. Faleloa site, Foa: radius UF 156956, 156961; tarsometatarsi UF 156810, 156835 (Figs. 3, 4), UF 156857 (Figs. 3, 4); pedal phalanges UF 156833, 156967. Tongoleleka site, Lifuka: sternum UF 158510; coracoid UF 158509 (Figs. 6, 7); scapulae UF 158681 (Fig. 8), UF 158735 (Fig. 8); humerus UF 158475; radii UF 158738, 158446/158488/158511 (fit together); carpometacarpi UF 158291, 158301; associated synsacrum and vertebrae UF 158485, 158486, 158488, 158490, 158491, 158495, 158499, 158501, 158502; femur UF 158267; tibiotarsi UF 158265 (Fig. 5), BPBM 165685 (Fig. 5); tarsometatarsi UF 158062, 158199; hallux UF 158427. Vaipuna site, 'Uiha: scapula UF 159162; tarsometatarsus UF 159094; pedal phalanges UF 159097, 159128, 159234. Mele Havea site, Ha`afeva: sternum UF 156113; radii UF 156398, 156461. `Anatu, `Eua: coracoid UF 150604 (Figs. 6, 7); ulna UF 152569; radius UF 152969; ulnare UF 151728; manus phalanges UF 152686, 152967; pedal phalanges UF 152203, 152446. Collapse Cave, `Eua: pedal phalanx UF 150709.

Diagnosis. Tongoenas belongs to the arboreal pigeon group (which also includes Hemiphaga, Ducula, Ptilinopus, Drepanoptila, Gymnophaps; see above) because of sharing characters 7, 9–11 of the tibiotarsus and 17–19, 21 of the tarsometatarsus (Table 1). These eight characters collectively exclude Tongoenas from any of the intermediate or terrestrial pigeons. Within the arboreal pigeon group, Tongoenas differs from the other genera, especially the sympatric Ducula and Ptilinopus, in these unique hindlimb characters. Tarsometatarsus (Figs. 3, 4): distal extent of crista plantaris mediana rounded and joins corpus tarsometatarsi more gradually; corpus tarsometatarsi stouter relative to corpus femoris and corpus tibiotarsi; fossa metatarsi I more distal; in dorsal aspect, foramen vasculare distale wider but less elongate; in dorsal or ventral aspect, the distal end flares more from corpus tarsometatarsi in both medial and lateral directions; trochlea metatarsi tertii longer. Tibiotarsus (Fig. 5): lateral margin of crista fibularis parallel (not oblique) to long axis of corpus tibiotarsi; canalis extensorius larger, deeper; lateral scar for retinaculum extensorium tibiotarsi located more proximal to condylus lateralis, and even proximal to proximal opening of canalis extensorius. Three elements of the pectoral girdle and wing of Tongoenas also distinguish it from other genera in the arboreal group, again, especially Ducula and Ptilinopus, as follows. Coracoid (Figs. 6, 7): facies articularis sternalis proportionately deeper, especially in medial half; facies articularis humeralis larger, with deeper depression between it and corpus coracoideus. Scapula (Fig. 8): less medio-lateral expansion (relative to shaft) of facies articularis clavicularis; facies articularis humeralis more protrudent from corpus scapulae. Radius (not depicted): sulcus ligamentum more convex. Among volant columbids, living or extinct, Tongoenas burleyi is exceeded in size only by the species of Goura.

Etymology. The name Tongoenas derives from combining Tonga (a Polynesian name for the island group where the pigeon once lived) with the Greek word oenas (feminine; a wild pigeon; Brown 1956:278). The species name burleyi is to honor archaeologist David V. Burley, whose many excavations of prehistoric sites in Tonga, including most of the sites that have produced specimens of Tongoenas, have yielded abundant materials of great cultural and biological importance.

Geological Age. Holocene and late Pleistocene. All specimens from Tongatapu and the Ha`apai Group are culturally associated and probably date from ~2850 to ~2700 cal BP (calibrated calendar years before present). Tongoenas burleyi became extinct after people colonized Tonga about 2850 cal BP, probably within a century or two of human arrival, like so many other Tongan species (Steadman et al. 2002b). It is unknown from historic (18th or 19th century) specimens or observations. On `Eua, the specimen of T. burleyi from Collapse Cave dates to ≤2850 cal BP by being associated with bones of introduced Rattus exulans. The specimens of T. burleyi from `Anatu are older (Steadman 1993): those from Layer II (five specimens) are >2850 cal BP but <60,000–80,000 years old; those from Layer III (two specimens) are >60,000–80,000 years old; and one other specimen is from mixed strata II/III.

Fred

Figure 1. The tarsometatarsus of selected Papuan-Oceanic columbids in dorsal aspect. A–F. Tongoenas burleyi, new genus and species. A. Holotype, Tongatapu, Tonga, UF 159857. B. Tongatapu, Tonga, UF 159469. C. `Uiha, Tonga, UF 159094. D. Foa, Tonga, UF 156835. E. Lifuka, Tonga, UF 158062. F. Foa, Tonga, UF 156857. G. Caloenas canacorum, Lifuka, Tonga, UF 158508 (reversed image). H–K. Ducula shutleri. H. `Eua, Tonga, UF 152051. I. `Eua, Tonga, UF 151882. J. Lifuka, Tonga, UF 158292. K. Ha`afeva, Tonga, UF 156286. L. Ducula rubricera, Isabel, Solomon Islands, UF 39400. M. Ducula pacifica, Espiritu Santo, Vanuatu, UF 43151. N. Hemiphaga novaeseelandiae, New Zealand, UF 25548. O. Gymnophaps albertisii, Papua New Guinea, UF 41466. P. Cryptophaps poecilorrhoa, Sulawesi, AMNH 298565 (reversed image). Scale bars = 10 mm.