ABSTRACT

A neotype is designated for Pelecanus aquilus Linnaeus, 1758 (currently Fregata aquila ; Aves, Fregatidae) to fix the identity of this nominal species.

KEY WORDS:
Ornithology; seabird; Suliformes; taxonomy; zoological nomenclature

Perhaps the most important element in the process of naming a taxon is the clear, unequivocal designation of a name-bearing type. However, this was not always so. In the years around the publication of the 'Systema Naturae', by Linnaeus in 1758Linnaeus C (1758) Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Holmiae [Stockholm], Laurentius Salvius, vol. 1, 10th ed., 826p., names were mainly based on texts and illustrations produced by naturalists and/or artists of the 17^th and 18^th centuries. In the absence of designated type specimens, those often impressive illustrations and/or meagre descriptions of that time have posed, and continue to pose, problems to taxonomists (Dubois & Nemésio 2007Dubois A, Nemésio A (2007) Does nomenclatural availability of nomina of new species and subspecies require the deposition of vouchers in collections? Zootaxa 1409: 1-22.).

An example of such problems is the formal description, by Johann Friedrich Gmelin, of the Southern Giant Petrel Macronectes giganteus (J.F. Gmelin, 1788). According to Voisin (1981Voisin J-F (1981) Quelle espèce Gmelin a-t-il décrite sous le nom de Procellaria gigantea ? Le Gerfaut, Revue belge d'Ornithologie 71: 251-255.), a painting and drawing by Sydney Parkinson, the artist on Captain James Cook's first voyage around the world (1768-1771), that were interpreted to represent 'types' of the Southern Giant Petrel actually depict specimens that cannot be identified to species. Its brief descriptive text, however, corresponds with the other species in the genus, the Northern Giant Petrel M. halli Mathews, 1912 (Voisin 1981Voisin J-F, Brooke RK, Bock WJ, Bourne WRP, Cooper J, Croxall JP, Escalante R, Haftorn S, Hogstad O, Humphrey PS, Hunter S, Jouanin C, Lambert K, Leraut P, Shaughnessy PD, Vuilleumier F, Warham J (1992) Case 2784. Procellaria gigantea Gmelin, [1789] (currently Macronectes giganteus ; Aves, Procellariiformes): proposed conservation of usage of the specific name by designation of a neotype. Bulletin of Zoological Nomenclature 49: 140-143.). In order to avoid disrupting the taxonomic stability, Voisin et al. (1992Voisin J-F, Brooke RK, Bock WJ, Bourne WRP, Cooper J, Croxall JP, Escalante R, Haftorn S, Hogstad O, Humphrey PS, Hunter S, Jouanin C, Lambert K, Leraut P, Shaughnessy PD, Vuilleumier F, Warham J (1992) Case 2784. Procellaria gigantea Gmelin, [1789] (currently Macronectes giganteus ; Aves, Procellariiformes): proposed conservation of usage of the specific name by designation of a neotype. Bulletin of Zoological Nomenclature 49: 140-143.) asked the International Commission on Zoological Nomenclature to use its plenary powers to validate a neotype of the Southern Giant Petrel for M. giganteus , and this was accepted in Opinion 1751 (ICZN 1993ICZN (1993) Opinion 1751. Procellaria gigantea Gmelin, [1789] (currently Macronectes giganteus ; Aves, Procellariiformes): usage of the specific name conserved by the designation of a neotype. Bulletin of Zoological Nomenclature 50: 298-299.).

In this contribution, we address a similar case involving another seabird species - the Ascension Frigatebird Fregata aquila (Linnaeus, 1758). The Ascension Frigatebird is a large seabird that currently breeds only on Boatswain Bird Islet near Ascension Island in tropical South Atlantic Ocean, and ranges at sea off West Africa from the Gulf of Guinea to the mouth of the Congo River (Orta 1992Orta J (1992) Fregatidae (frigatebirds), p. 362-374. In: del Hoyo J, Elliot A, Sargatal J (Eds.) Handbook of the birds of the World. Barcelona, Lynx Edicions, vol. 1, 696p., Ashmole et al. 1994Ashmole NP, Ashmole MJ, Simmons, KEL (1994) Seabird conservation and feral cats on Ascension Island, South Atlantic, p. 94-121. In: Nettleship DN, Burger J, Gochfeld M (Eds.) Seabirds on Islands: threats, case studies and action plans. Cambridge, Birdlife International, 318p., Ratcliffe et al. 2008Ratcliffe N, Pelembe T, White R (2008) Resolving the population status of Ascension Frigatebird Fregata aquila using a 'virtual ecologist' model. Ibis 150: 300-306. doi: 10.1111/j.1474-919X.2007.00778.x
https://doi.org/10.1111/j.1474-919X.2007... ). It is a member of the family Fregatidae Degland & Gerbe, 1867, which contains five living species and 13 subspecies, all in Fregata Lacépède, 1799, distributed throughout tropical and subtropical oceans. Frigatebirds have a mostly black plumage (particularly males), long pointed wings, deeply forked tails, and long hooked bills. Adult females have a varying amount of white mostly on breast and belly. Juveniles are white or rufous-headed and have extensive white on underparts (Harrison 1991Harrison P (1991) Seabirds: An Identification Guide. London, Christopher Helm, 2nd ed., 448p., Orta 1992Orta J (1992) Fregatidae (frigatebirds), p. 362-374. In: del Hoyo J, Elliot A, Sargatal J (Eds.) Handbook of the birds of the World. Barcelona, Lynx Edicions, vol. 1, 696p., Walbridge et al. 2003Walbridge G, Small B, McGowan RY (2003) Ascension Frigatebird on Tiree - new to the Western Palearctic. British Birds 96: 58-73.).

Linnaeus (1758Linnaeus C (1758) Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Holmiae [Stockholm], Laurentius Salvius, vol. 1, 10th ed., 826p.: 133) described the Ascension Frigatebird under the name Pelecanus aquilus as follows: 'P[elecanus] cauda forficata , corpore nigro , capite abdomineque albis ' (tail forked, body black, white on head and belly). The name Linnaeus used for this species repeats that previously used by Johan Lorens Odhelius in his 1754 dissertation entitled 'Chinensia Langerströmiana' (formally published under Linnaeus' name in 'Amoenitates Academicae'; Linnaeus 1759Linnaeus C (1759) Amoenitates academicae; seu dissertationes variae physicae, medicae, botanicae, antehac seorsim editae, nunc collectae et auctae, cum tabulis aenaeis. Holmiae [Stockholm], Laurentius Salvius, vol. 4, 600p.) and by Pehr Osbeck in his 1757 'Dagbok öfwer en Ostindisk resa åren 1750, 1751, 1752', translated into English by Johann Reinhold Forster in 1771 (Osbeck 1757Osbeck P (1771) A voyage to China and East Indies. London, Benjamin White, vol. 2, 499p. [1771]). The works by both Odhelius and Osbeck are binomial, but being earlier than 1758, are unavailable under Article 3.2 of the Fourth Edition of the International Code of Zoological Nomenclature, hereafter 'the Code' (ICZN 1999ICZN (1999) The International code of zoological nomenclature. London, The International Trust for Zoological Nomenclature, The Natural History Museum, 4th ed., xxix+336p.). In his description of Pelecanus aquilus , Linnaeus (1758Linnaeus C (1758) Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Holmiae [Stockholm], Laurentius Salvius, vol. 1, 10th ed., 826p.) also included five other earlier references to it: 'Alcyon major pulla ' (Browne 1756Browne P (1756) The civil and natural history of Jamaica. London, The Author , viii+503p.), 'Cari pira [avis Brasil]' (de Laet 1633), 'Man of Var [= War]' (Sloane 1707Sloane H (1707) A voyage to the islands Madera, Barbados, Nieves, S. Christophers and Jamaica: with the natural history of the herbs and trees, four-footed beasts, fishes, birds, insects, reptiles, &c. of the last of those islands. London, The Author , vol. 1, xlix+264p.), 'Avis Rabo forcado' (Petiver 1764Petiver J (1764) Jacob Petiver opera historiam naturalem spectantia; or Gazophylaceum containing several 1000 Figures of Birds, Beasts, Reptiles, Insects, Fish, Beatles, Moths, Flies, Shells, Corals, Fossils, etc, from all Nations on 156 Copperplates, with English and Latin Names. London, John Millan, 452p. [1702-1706]), and 'Frigate bird' (Albin 1738Albin E (1738) A natural history of birds: illustrated with a hundred and one copper plates, curiously engraven from the life. London, The Author, vol. 3, 95p.). He also added 'Habitat in Insula Adscensionis aliisque pelagicis ' (Ascension Island and the open sea) as the locality for the species.

By the end of the 19^th century, only two valid species of frigatebirds were generally recognized, the larger Ascension Island frigatebird occurring in all tropical oceans, and a smaller frigatebird, Fregata ariel (G.R. Gray, 1845) restricted to Indian and Pacific Oceans (Ogilvie-Grant 1898Ogilvie-Grant WR (1898) Catalogue of birds in the British Museum, Volume XXVI. Catalogue of the Plataleae, Herodiones, Steganopodes, Pygopodes, and Impennes in the collection of the British Museum. London, British Museum (Natural History), xvii+687p.). Mathews (1914Mathews GM (1914) On the species and subspecies of the genus Fregata . The Austral Avian Record 2: 117-121.) revised frigatebird taxonomy, naming new taxa and determining the status of names already published. There (p. 117-118) he argued that the name F. aquila was applicable exclusively to birds from Ascension Island, since it was based on a specimen collected there by Osbeck. Furthermore, in his 'Birds of Australia', he (Mathews 1915Mathews GM (1915) The birds of Australia. London, Witherby & Co., vol. 4, part 3, xii+141p.: 243) opined that the five 'pre-Linnaean' names quoted in the preceding paragraph were 'purely of historical interest'.

As to the first point, we agree with Mathews (1914Mathews GM (1914) On the species and subspecies of the genus Fregata . The Austral Avian Record 2: 117-121.) that Linnaeus's description, ultimately taken from Odhelius's dissertation, is essentially a summary in Latin of a longer text from Osbeck (1757Osbeck P (1771) A voyage to China and East Indies. London, Benjamin White, vol. 2, 499p. [1771]), who (p. 88) described a frigatebird from Ascension Island, recording its plumage as: 'the colour of the whole body... is black: but the head, breast, belly, and fore part of the neck are of a fine white'. This pattern recalls that of a juvenile Ascension Frigatebirds, wherein, however, a complete or broken black band runs across the upper-chest (Harrison 1991Harrison P (1991) Seabirds: An Identification Guide. London, Christopher Helm, 2nd ed., 448p., Walbridge et al. 2003Walbridge G, Small B, McGowan RY (2003) Ascension Frigatebird on Tiree - new to the Western Palearctic. British Birds 96: 58-73.).

Osbeck was a student of Linnaeus who travelled to Asia in 1750-1752 and brought home a collection of natural items, chiefly from China (Merril 1916Merrill ED (1916) Osbeck's Dagbok Ofwer en Ostindsk Resa. American Journal of Botany 3: 571-588.). En route he collected a speci men of the Ascension Frigatebird, as inferred from Odhelius (in Linnaeus 1759Linnaeus C (1759) Amoenitates academicae; seu dissertationes variae physicae, medicae, botanicae, antehac seorsim editae, nunc collectae et auctae, cum tabulis aenaeis. Holmiae [Stockholm], Laurentius Salvius, vol. 4, 600p.: 239): 'Avis in insula Ascensionis a P. Osbeck capta' (a bird captured by P. Osbeck on Ascension Island). Never theless, there is nothing to clearly suggest that Odhelius, or even Linnaeus, ever saw this specimen themselves, or that it is still extant (cf., e.g., Walling 1992Walling L (1992) Linnaean specimens in the Zoological Museum of Uppsala University. Archives of Natural History 19: 219-230. doi: 10.3366/anh.1992.19.2.219
https://doi.org/10.3366/anh.1992.19.2.21... , Zoology Section 1996Zoology Section (1996) Catalogue of type specimens. 2. General zoology. Uppsala, Uppsala University, Museum of Evolution, 78p., 2001Zoology Section (2001) Catalogue of type specimens. 4. Linnaean specimens. Uppsala, Uppsala University, Museum of Evolution, 128p.). As to the other point, that pre-Linnaean names are of historical interest only, it is necessary to note that, according to the Article 72.4.1 of the Code (ICZN 1999ICZN (1999) The International code of zoological nomenclature. London, The International Trust for Zoological Nomenclature, The Natural History Museum, 4th ed., xxix+336p.), 'the type series of a nominal species-group taxon consists of all the specimens included by the author in the new nominal taxon (whether directly or by bibliographic reference), except any that the author expressly excludes'. Therefore, all the specimens described and/or illustrated by authors quoted by Linnaeus (1758Linnaeus C (1758) Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Holmiae [Stockholm], Laurentius Salvius, vol. 1, 10th ed., 826p.) in his description of Pelecanus aquilus are, in principle, syntypes.

The Irish physician and botanist Patrick Browne briefly diagnosed his Alcyon major pulla as: 'cauda longiore bifurca ' (long forked tail) and added: 'The Man-of-war bird; or the dark-coloured Alcyon with slender forked tail' (Browne 1756Browne P (1756) The civil and natural history of Jamaica. London, The Author , viii+503p.: 483). The word 'Alcyon ' comes from the Ancient Greek word ἀλκυών (alkuōn), which means 'Kingfisher' (Jobling 2010Jobling JA (2010) Helm dictionary of scientific bird names. London, Christopher Helm , 432p.). Thus, the species name translates as 'The Greater dark Kingfisher', no doubt a reference to the species feeding on fish (Orta 1992Orta J (1992) Fregatidae (frigatebirds), p. 362-374. In: del Hoyo J, Elliot A, Sargatal J (Eds.) Handbook of the birds of the World. Barcelona, Lynx Edicions, vol. 1, 696p.). In the Caribbean, where Browne lived for many years, frigatebirds were called by English sailors as 'Man-of-War bird', the term itself derived from a British Royal Navy expression for a class of warship. Browne (1756Browne P (1756) The civil and natural history of Jamaica. London, The Author , viii+503p.) neither designated nor illustrated a specimen, but his allusion to a 'wholly dark bird with forked tail' suggests a male Magnificent Frigatebird F . magnificensMathews, 1914Mathews GM (1914) On the species and subspecies of the genus Fregata . The Austral Avian Record 2: 117-121., since it is the only member of the family that breeds in the Caribbean (Orta 1992Orta J (1992) Fregatidae (frigatebirds), p. 362-374. In: del Hoyo J, Elliot A, Sargatal J (Eds.) Handbook of the birds of the World. Barcelona, Lynx Edicions, vol. 1, 696p.).

In the Latin edition of his 'History of the New World' (de Laet 1663de Laet J (1663) Novus orbis seu Descriptionis Indiae Occidentalis, Libri XVIII. Lugdunum Batavorum [Leiden], Elzevirios, 708p.), the Dutch geographer Johannes de Laet mentioned a seabird from Brazil called 'Caripira', of which he said 'caudam habet bifurcatam, unde & nomen invenit apud Hispanos Raboforcado' (has a forked tail, hence its name Raboforcado among the Spanish). The word 'Caripira' is a corruption of the word 'Grapirá', which is a Brazilian indigenous (Tupi-Guarani) name for the Magnificent Frigatebird (Ihering 1940Ihering R (1940) Dicionário dos animais do Brasil. São Paulo, Diretoria de Publicidade Agrícola, 898p.). 'Rabiforcado' is an old Spanish spelling of 'Rabihorcado' (forked tail; Hartog 1993Hartog JC (1993) An early note on the occurrence of the Magnificent Frigate Bird [sic], Fregata magnificens Mathews, 1914, in the Cape Verde Islands: Columbus as an ornithologist. Zoologische Mededelingen 67: 361-364.). Laet neither mentioned nor illustrated specimens.

During his voyage to Jamaica, the Irish naturalist Hans Sloane reported he saw several 'Men of War Birds [sic]' while passing near Barbados (Sloane 1707Sloane H (1707) A voyage to the islands Madera, Barbados, Nieves, S. Christophers and Jamaica: with the natural history of the herbs and trees, four-footed beasts, fishes, birds, insects, reptiles, &c. of the last of those islands. London, The Author , vol. 1, xlix+264p.: 30). He quoted other authors who had also described frigatebirds in their works, de Laet (1663de Laet J (1663) Novus orbis seu Descriptionis Indiae Occidentalis, Libri XVIII. Lugdunum Batavorum [Leiden], Elzevirios, 708p.) among them. Again no specimen was illustrated or otherwise reported.

In 1702-1706, James Petiver, an English apothecary known for his contributions to natural history, published 'Gazophylaceum naturae et artis', a descriptive catalogue of animals and plants from different parts of the World. This work was collected with others posthumously republished in 1764 under the title ' Jacob Petiver Opera, historiam naturalem spectantia' (Weiss 1927Weiss HB (1927) James Petiver's Gazophylacii. Journal of the New York Entomological Society 35: 411-414.). There, Petiver (1764Petiver J (1764) Jacob Petiver opera historiam naturalem spectantia; or Gazophylaceum containing several 1000 Figures of Birds, Beasts, Reptiles, Insects, Fish, Beatles, Moths, Flies, Shells, Corals, Fossils, etc, from all Nations on 156 Copperplates, with English and Latin Names. London, John Millan, 452p.) gave an illustration (plate LIV, fig. 2) and brief text of 'The Indian Forked Tail'. Its text reads: 'This bird's tail open and shuts like a Taylor's sheers, and for that reason the Portuguese call it Rabo Forcado'. As noted by Edwards (1760Edwards G (1760) Gleanings of natural history, exhibiting figures of quadrupeds, birds, insects, plants, etc. most of which have not, till now, been either figured or described. London, The Author , xxxv+220p.: 211), Petiver copied both the figure and text from Willughby's 'Ornithology' (1678Willughby F (1678) The ornithology of Francis Willughby of Middleton in the county of Warwick Esq...: in three books: wherein all the birds hitherto known, being reduced into a method sutable [sic] to their natures, are accurately described: the descriptions illustrated by most elegant figures, nearly resembling the live birds, engraven in LXXVII copper plates. London, John Martyn, 636p.: 395; plate LXXVII). This figure, reproduced here as Fig. 1, is very imprecise, and were it not for the fact that the name 'Rabo forcado' has been mentioned, we would hardly associated the bird represented with a frigatebird.

Eleazar Albin, a German-born, English wildlife illustrator, published 'A natural history of birds' in 1731-1738. Its paintings were based on actual birds, either living individuals or prepared specimens. Plate LXXX (Albin 1738Albin E (1738) A natural history of birds: illustrated with a hundred and one copper plates, curiously engraven from the life. London, The Author, vol. 3, 95p.: 75) illustrated an oddly-perched individual titled 'The Frigate Bird' (Fig. 2), with the attached description: 'The Males are as black as Ravens... He has great red Gills under his throat... which do not appear but in the old ones, the Females had none; they are whiter than Males, especially under the Belly'. According to Albin (1738Albin E (1738) A natural history of birds: illustrated with a hundred and one copper plates, curiously engraven from the life. London, The Author, vol. 3, 95p.), the specimen depicted came from an island in the Caribbean called 'Isle of Frigats'. It is clearly a male (the all-black plumage and red gular pouch are unmistakable; Fig. 2), and probably a Magnificent Frigatebird F. magnificens .

Figures 1-2
(1) Plate LIV, figure 2 of Petiver (1764Petiver J (1764) Jacob Petiver opera historiam naturalem spectantia; or Gazophylaceum containing several 1000 Figures of Birds, Beasts, Reptiles, Insects, Fish, Beatles, Moths, Flies, Shells, Corals, Fossils, etc, from all Nations on 156 Copperplates, with English and Latin Names. London, John Millan, 452p. [1702-1706]), named 'The Indian Forked Tail'. (2) Plate LXXX of Albin (1731Albin E (1738) A natural history of birds: illustrated with a hundred and one copper plates, curiously engraven from the life. London, The Author, vol. 3, 95p.), named the 'The Frigate Bird'. Note the all-black plumage and red gular pouch characteristic of adult male frigatebirds.

In summary, none of the accounts of syntypic material cited by Linnaeus (1758Linnaeus C (1758) Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Holmiae [Stockholm], Laurentius Salvius, vol. 1, 10th ed., 826p.) in his original description of Pelecanus aquilus applies unambiguously to the Ascension Island Frigatebird; at least one, however, could involve the Magnificent Frigatebird (Browne 1756Browne P (1756) The civil and natural history of Jamaica. London, The Author , viii+503p.). Lectotypifying the lost specimen collected by Osbeck on Ascension Island cannot fix the identity of Pelecanus aquilus either because, in the central Atlantic, it can be argued that the specimen could have been a stray of any of three other species of frigatebirds: F. ariel , F. minor (J.F. Gmelin, 1789) and F. magnificens . Thus neotypification provides the only solution if the name aquilus (-a) is to be tied unchallengeably to the Ascension Island frigatebird, the species for which it has been used for over a century. Accordingly, we choose as neotype of Pelecanus aquilus Linnaeus, 1758: BMNH 1899.1.4.13, adult breeding male, collected on Ascension Island by Dr. Frank Penrose in December 1877, and now in the Natural History Museum at Tring, UK (Fig. 3). Its measurements (in mm) are: bill (culmen from forehead), 88.3; wing (unflattened chord, from the carpal joint to the tip of the longest primary), 557; tail (from the point of insertion of central rectrices to the tip of the longest rectrix), 352; and tarsus (from the intertarsal joint to the base of the toes), 16.8. This designation satisfies the provisions of Article 75, Neotypes, of the Code (ICZN 1999ICZN (1999) The International code of zoological nomenclature. London, The International Trust for Zoological Nomenclature, The Natural History Museum, 4th ed., xxix+336p.) by clarifying taxonomic identity and type locality of the Ascension Island frigatebird (Article 75.3.1); nominating its size and green gloss on dorsum and upper-wing coverts as diagnostic characters (Article 75.3.2); providing data and description sufficient to ensure recognition of the specimen designated (Article 75.3.3); giving reasons and references for believing that original type material is lost (Article 75.3.4); selecting a neotype consistent with descriptions of at least some of the former syntypic material (Article 75.3.5); choosing a neotype from the most specific of the originally cited type localities, Ascension Island (Article 75.3.6); and recording that the neotype is the property of a recognized scientific institution (Article 75.3.7).

Figure 3
Neotype of Fregata aquila (Linnaeus, 1758): Ventral, lateral, and dorsal views of specimen BMNH 1899.1.4.13 in the Natural History Museum at Tring, UK. Scale bar: 30 cm.

ACKNOWLEDGMENTS

The MS benefited from valuable comments and suggestions made by two anonymous reviewers and Richard Schodde. This contribution is part of an ongoing research, by CJC, on the systematics of frigatebirds and received support from Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brazil.

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