Gallirallus pisonii, 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 : 10-17

† Gallirallus pisonii new species

Holotype. Complete coracoid UF 62934 ( Figure 2 A) from the Pisonia Rockshelter archaeological site, Aguiguan, Commonwealth of the Northern Mariana Islands.

Paratypes. Rostrum anterior to nares UF 62918. Incomplete mandibles UF 62912–62914, 62926, 62946, 62947. Complete quadrates UF 62888, 62889, 62941. Complete and partial vertebrae UF 62880, 62890, 62919 (lot of 10), 62933, 62943, 62955. Incomplete sterni UF 62892/62893 ( Figure 3 A, two pieces glued together), 62922. Humeral and sternal ends of coracoids UF 62881, 62884, 62910, 62911, 62931, 62939, 62940. Anterior scapulae UF 62878, 62915, 62916. Incomplete humeri UF 62887, 62902, 62903. Distal ulna UF 62925. Distal radius UF 62953. Incomplete carpometacarpi UF 62882, 62883, 62917 ( Figure 2 A), 62923, 62924. Complete phalanx 1 of digitalis majoris UF 62938. Incomplete synsacrum UF 62948. Femoral shaft UF 62875. Proximal and distal tibiotarsi UF 62876, 62894–62901, 62927, 62937, 62944. Proximal fibulae UF 62932, 62942, 62954. Proximal and distal tarsometatarsi UF 62877, 62879, 62904–62909, 62928, 62929, 62949–62952. Pedal phalanges UF 62870–62873, 62874 (lot of nine), 62855, 62886 (lot of six), 62891 (lot of 48), 62920, 62921 (lot of 13), 62930 (lot of nine), 62935, 62936 (lot of 22), 62945 (lot of 24), 62956.

Diagnosis. A small to medium­sized rail (smaller than Gallirallus philippensis ; Table 3) with the following unique combination of characters (summarized in Table 4 ).

Mandible: fenestra mandibulae caudalis large. Sternum: angle of crista lateralis, relative to dorsal margin in lateral aspect, ca. 50°; carina sterni higher than in G. owstoni but lower than in G. philippensis . Coracoid: facies articularis sternalis narrow, shallow; impressio musculo sternocoracoracoidei less concave; corpus coracoidei, in dorsal aspect, wide relative to processus procoracoideus; facies articularis clavicularis protruding little from corpus coracoidei. Scapula: in proximal aspect, area between facies articularis humeralis and facies articularis clavicularis shallow. Humerus: caput humeri shallow in proximal aspect; incisura capitis shallow. Carpometacarpus: short and slender relative to leg elements.

Etymology. Named after the type locality, Pisonia Rockshelter , which in turn was named after an immense tree of Pisonia grandis that grew nearby and provided badly needed shade while Connie Bodner, Scott Derrickson, John Groves, and David Lee worked with Steadman to excavate the site in 1994. The name pisonii is a genitive adjective.

mean, range, and sample size. M = male, F = female, U = unknown sex, ­­­ = cannot be evaluated.

G. philippensis is volant; all others are flightless.

G. owstoni G. o w s t o n i † G. temptatus † G. pisonii M F U U Guam, Marianas Guam, Marianas Rota, Marianas Aguiguan, Marianas

Coracoid 23.6 22.8 22.3 24.4

Total length 22.9–24.7 21.6–24.3 1 1 7 11

Sternal facet width 6.2 5.9 5.2 6.0 6.1–6.3 5.2–6.2 1 1 7 11

Minimum shaft width 2.6 2.6 2.5 2.7 2.5–2.8 2.3–3.0 1 1 7 11

Humerus 47.5 44.7 ­­­ ­­­

Total length 45.3–51.1 42.9–46.8

7 11

Distal width 6.5 6.1 ­­­ ­­­ 6.3–6.7 5.9–6.3

7 11

Minimum shaft width 2.8 2.7 ­­­ ­­­ 2.6–3.1 2.6–3.0

7 11

Ulna 39.1 36.6 ­­­ ­­­

Total length 36.8–41.5 34.8–38.7

7 11

Minimum shaft width 3.0 2.7 ­­­ ­­­ 2.8–3.2 2.6–3.0

7 11

Carpometacarpus 25.0 23.6 ­­­ ­­­

Total length 23.0–26.7 22.1–25.1

7 11

Femur 56.0 52.4 ­­­ ­­­

Total length 54.0–59.2 49.2–54.6

7 11

Distal width 9.5 8.7 ­­­ ­­­ 8.9–9.9 8.4–9.0

7 11

Minimum shaft width 3.8 3.6 ­­­ ­­­ 3.3–4.0 3.4–3.9

7 11

Tarsometatarsus 51.9 48.5 47.4 ­­­

Total length 48.7–54.9 46.2–50.6 1

7 11

Proximal width 7.6 7.1 6.6 5.6 7.0–8.2 6.7–7.3 6.4–6.8 5.6–5.7 7 11 2 2

Distal width 8.0 7.4 7.4 6.1 7.4–8.5 7.2–7.6 1 1 7 11

Minimum shaft width 3.8 3.4 3.4 3.0 3.5–4.0 3.2–3.8 3.3–3.5 3.0–3.1 7 11 2 2

† G. pendiculentus G. philippensis G. philippensis U M F

Tinian, Marianas Oceania* Oceania*

Coracoid 21.7 26.8 23.2 Total length 20.2–23.7 26.2–27.5 21.8–24.5

7 6 6

Sternal facet width 5.6 6.6 5.5 5.3–5.9 6.1–7.3 5.1–5.9 5 6 6

Minimum shaft width 2.4 3.0 2.8 2.2–2.7 2.7–3.2 2.5–3.0 9 6 6

Humerus 42.0 51.3 45.6 Total length 41.2–42.7 49.2–53.0 41.5–49.3

2 6 6

Distal width 6.2 7.1 6.1 5.7–7.1 6.9–7.5 5.9–6.3 17 6 6

Minimum shaft width 2.8 3.3 2.9 2.6–3.1 3.2–3.4 2.7–3.3 13 5 6

Ulna 36.0 43.9 39.2 Total length 34.6–38.0 41.4–44.8 35.2–43.6

3 6 6

Minimum shaft width 2.4 3.0 2.7 2.2–2.5 2.8–3.1 2.6–2.8 9 6 6

Carpometacarpus 23.3 29.0 26.3 Total length 1 27.0­30.3 24.4­29.4 4 6

Femur 50.8 53.8 47.3 Total length 47.5­53.2 51.3­54.9 45.0­49.7 5 6 6

Distal width 8.1 8.7 7.4 7.5–9.1 8.4–9.1 7.0–7.9 9 6 6

Minimum shaft width 3.4 4.0 3.3 3.1–3.5 3.7–4.2 3.1–3.5 7 6 6

Tarsometatarsus 41.6 48.0 42.5 Total length 38.4–46.5 45.3–49.0 40.8–45.2

7 6 6

Proximal width 6.2 7.0 6.1 5.6–7.3 6.7–7.2 5.8–6.6 17 6 6

Distal width 6.5 7.1 6.3 6.1–6.8 6.7–7.5 6.0–6.9 14 6 6

Minimum shaft width 3.1 3.5 3.0 2.7–3.7 3.1–3.6 2.8–3.3 17 6 6

Width of distal end relative to length and wide ­­­ ­­­width of corpus humeri

Depressio musculo brachialis deep, with distinct shallow, with shallow, with indistinct

margin indistinct margin margin

Carpometacarpus

Remarks. We suspect that † G. pisonii probably was flightless, although skeletal measurements do not strongly support this statement. For example, the sternum UF 62892/ 62893 has a carinal depth of 10.8 mm and a sternal width at the sulcus articularis coracoidei of 10.7 mm, values that are intermediate between those in modern specimens of the volant G. philippensis and the flightless G. owstoni . The shaft of the holotypical coracoid is slender and the carpometacarpus is very small, indicating reduced flight capability. The leg bones of † G. pisonii cannot be reliably distinguished from those of G. philippensis .

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 3. The sternum of Gallirallus in lateral (left) and ventral (right) aspects. A. G. pisonii new species, UF 62892 / 62893, Aguiguan. B. † G. pendiculentus new species, UF 60142, Tinian. C. G. owstoni male, UF 39920, Guam. D. G. philippensis female, UF 43222, Efate, Vanuatu. Scale = 40 mm.

Tables

TABLE 4. Character summary for species of Gallirallus from the Mariana Islands compared to the extant, volant G. philippensis. ant. = anterior; art. = articularis; dis. = distal; imp. = impressio; m. = musculo; post. = posterior; proc. = processus; prox. = proximal.

Skeletal element and character	G. owstoni Guam	† G. temptatus Rota	† G. pisonii Aguiguan
Mandible
Size relative to overall body size	small	small	small
Fenestra mandibulae caudalis	small	­­­	large
Sternum