Papasula abbotti nelsoni ssp. nov. (1 Viewer)

[Fred Ruhe]

JULIAN P. HUME. 2023

A new fossil subspecies of booby (Aves, Sulidae: Papasula) from Mauritius and Rodrigues, Mascarene Islands, with notes on P. abbotti from Assumption Island

Zootaxa 5270 (3): 507–536
doi:10.11646/zootaxa.5270.3.5

Abstract: A new fossil subspecies of booby (Aves, Sulidae: Papasula ) from Mauritius and Rodrigues, Mascarene Islands, with notes on P. abbotti from Assumption Island | Zootaxa

A new subspecies of Papasula booby is described from fossil remains collected in the Mascarene Islands of Mauritius and Rodrigues, southwestern Indian Ocean. The Mascarene Booby Papasula abbotti nelsoni ssp. nov., larger than nominate Abbott’s Booby P. a. abbotti from Christmas Island, northeast Indian Ocean, was approximately the same size as the extinct Hiva Oa Booby P. a. costelloi from the Marquesas in the Eastern Pacific. Mentioned in early accounts of Mauritius in 1668 and in 1725–26 and 1761 on Rodrigues, the Mascarene booby became extinct by the end of the 18th century. Members of another isolated but now extirpated population of Papasula abbotti from Assumption Island in the Seychelles Archipelago, the island from which the type specimen was collected, are identical to extant Christmas Island birds in size and colouration and discussed in detail herein.

Enjoy,

Fred

 

[Melanie]

A new entry for the BotW key:

Papasula abbottii ssp. nelsoni

Etymology: Named after British ornithologist Joseph Bryan Nelson (14 March 1932–29 June 2015), who first
recognised the presence of a Papasula booby on the Mascarenes, and whose ground-breaking studies on sulids and
especially Papasula abbotti are still relevant today.

 

[Fred Ruhe]

Systematics

Class Aves
Order Suliformes Sharpe, 1891
Family Sulidae Reichenbach, 1849
Genus Papasula Olson and Warheit, 1988

Type (by monotypy) Papasula abbotti Olson & Warheit, 1988

Osteological diagnosis and comparison. The following osteological characters in combination characterize the genus Papasula. The fossil specimens are much larger than those of species in most other marine bird genera occurring in the Mascarenes, including those in Oceanitidae, Phaethontidae, Laridae, Stercorariidae, and in all Procellariidae except Macronectes giganteus. Papasula abbotti is smaller than M. giganteus and all species of Diomedeidae. It differs from similar-sized Fregata ariel and F. minor as follows. Coracoid: smaller, more gracile, and processus lateralis much less extensive. Sternum: larger; in lateral view, sulcus articularis coracoideus bordered with a much larger labrum interna and tuberculum labri externa; in dorsal view, foramina pneumatici larger, much more extensive. Humerus: more gracile, much thinner in the shaft and particularly lacks a sharply angular crista deltopectoralis. Ulna: much smaller; cotyla dorsalis larger and directed distad; impressio brachialis much more excavated; papillae remigales much less pronounced. Tarsometatarsus: most notably by much larger size, extremely reduced in length and width in Fregata, and sulcus extensorius much more deeply excavated. The Papasula material described herein is further assigned to Sulidae by the characters identified in Olson & Warheit (1988), Steadman et al. (1988), and van Tets et al. (1988), who also mentioned diagnostic characters of the cranial and other parts of the postcranial skeleton not discussed here.

Papasula abbotti nelsoni ssp. nov.
Sula piscator Milne-Edwards, 1873, p.22, pl. 11, figs. 5, 5a, 5b, 5c.
Sula capensis Milne-Edwards, 1875, p.8.
Gannet E. Newton & Gadow, 1893, p.282.
Sula abbotti Nelson, 1974, p.368; Bourne, 1976, p.119; Cheke, 1987, p.31.
Sula (Papasula) abbotti Cheke, 2001, p.73.
Papasula abbotti, Cheke & Hume, 2008, p.47; Hume, 2013, p.216.
Papasula sp., Hume, 2017, p.84.

Holotype: Left humerus UMZC 262.AA

Type Locality: Mare aux Songes, southeast Mauritius (20826051, 200 S; 57841023, 500 E)

Distribution: Mauritius and Rodrigues, Mascarene Islands.

Etymology: Named after British ornithologist Joseph Bryan Nelson (14 March 1932–29 June 2015), who first recognised the presence of a Papasula booby on the Mascarenes, and whose ground-breaking studies on sulids and especially Papasula abbotti are still relevant today.

Paratype: Left ulna UMZC 262.AA (almost certainly associated with Holotype), Mare aux Songes, southeast Mauritius,

Referred fossil material: All collected from unspecified caves on the Plaine Corail, Rodrigues: coracoid NHMUK PV A9076 (Ld) (Fig. 2); cranial fragment of sternum NHMUK PV A9076 humerus (Lp) NHMUK PV A9049; ulna MNHN 6574 (Rd); NHMUK PV A9076 (Rd); tarsometatarsus UMZC 995 (R)

Diagnosis: As for genus.

Chronology: No dates are available from bird remains from the 19th century Mare aux Songes (MAS) collections (Basin 0), but 14C dates exist for MAS fossil remains of endemic giant tortoises Cylindraspis ssp., which became extinct c.1730, that were excavated from the same horizon as the Mascarene booby elements (Hume et al. 2021). The dates range from ca. 1260 to 1830 YBP (Burleigh & Arnold 1986). On Rodrigues, a partial humerus of the endemic owl Otus murivorus (Milne-Edwards, 1873), collected from 60–75 cm below surface in Caverne Dora on the Plain Corail, produced a radiocarbon age of 2850 ± 30 with a calibrated age range of 3060–2870 YBP (Burney et al. 2015). This suggests very low sedimentation rates in the late Holocene (Hume 2013; Burney et al. 2015). Although the precise cave from which P. a. nelsoni was collected is unknown, many of the caves on the Plaine Corail have depositional environments similar to that of Caverne Dora (Hume 2005, 2013).

Fred


Figure 1. Comparison of humeri of Papasula abbotti nelsoni ssp. nov. with Papasula abbotti abbotti, caudal surface, left side. A. NHMUK PVA9049 P. a. nelsoni (Plaine Corail, Rodrigues); B. UMZC 262.AA holotype P. a. nelsoni (Mare aux Songes, Mauritius); C. USNM 560863 P. a. abbotti u/s (Christmas Island); USNM 560862 P. a. abbotti immature u/s (Christmas Island). Abbreviations: td, tuberculum dorsale; tv, tuberculum ventrale; ch, caput humeri; ic, incisura capitis; mc, margo caudalis; cvf, crus ventrale fossa; cb, crista bicipitalis; fp, fossa pneumotricipitalis; sh, sulcus humerotricipitalis; ss, sulcus scapulotricipitalis; pf, processus flexorius. Scale bar = 20 mm.

Figure 2. Comparison of proximal humeri of Papasula abbotti nelsoni ssp. nov. with Papasula abbotti abbotti, cranial surface, left side. A. NHMUK PVA9049 P. a. nelsoni (Plaine Corail, Rodrigues); B. UMZC 262.AA holotype P. a. nelsoni (Mare aux Songes, Mauritius); C. ANWC 40544 P. a. abbotti F (Christmas Island). Abbreviations: st, sulcus lig. transversus; cb, crista bicipitalis. Scale bar = 10 mm.