A revision of large extinct members of Strigidae described from Quaternary cave deposits in Cuba here reduces the number of valid taxa from five to three. Ornimegalonyx oteroiArredondo, 1958a, is the only valid species of the four previously described in the genus. The type series of Bubo osvaldoiArredondo & Olson, 1994, is revealed to be a composite, comprising two different species in the genera Bubo Duméril, 1805, and OrnimegalonyxArredondo, 1958a, with the latter described herein as a new, diminutive species.
Confused with a terror bird (Phorusrhacidae Ameghino) because of its gigantic size (Arredondo 1954, 1955, 1956, 1957a,b, 1958a,b, Koopman 1958), the extinct genus Ornimegalonyx was erected by Arredondo (1958a) on the basis of post-cranial elements from Cueva de Pío Domingo, Pinar del Río province, western Cuba. The material was collected from the floor of the cave on 2 January 1954 by members of the Sociedad Espeleológica de Cuba (SEC). Subsequently, Brodkorb (1961) realised that this taxon actually belonged to the family Strigidae due to the presence of an ossified supratendinal bridge in the tarsometatarsus. He designated a lectotype for the type species: Ornimegalonyx oteroi Arredondo, 1958a. Arredondo (1975) later summarised the taxonomic history of O. oteroi, including synonyms, new material and localities. He believed that a number of specimens that were larger or smaller than the type material (a single individual) represented new species (contra Brodkorb's opinion, see Arredondo 1975: 140). Apparently discarding the possibility of considerable intraspecific variation in so large a raptor (see also Kurochkin & Mayo 1973: 59), those specimens, mostly from western Cuba, were described as O. acevedoi, O. minor and O. gigas, respectively, with the result that four synchronic species in the genus were recognised as having occurred sympatrically in Cuba during the Quaternary (Arredondo 1982: 45–47).
In 1947, a decade prior to the description of Ornimegalonyx, A. Moreno of the Museo Felipe Poey, La Habana, sent to A. Wetmore, at the Smithsonian Institution, Washington DC (USNM), two fossil bones of a large bird from eastern Cuba for study (Arredondo & Olson 1994: 436). Wetmore (1959: 15) identified them as a giant barn owl, Tytonidae, but this was never published. Thirty-five years later, Arredondo & Olson (1994) reassessed the material (Fig. 1B–C)—a near-complete right femur (USNM 447022) and partial humerus (USNM 447023). They identified it with fossils of a large extinct strigid discovered in western Cuba, which was named Bubo osvaldoi Arredondo & Olson, 1994. Both east Cuban bones were included in the type series of B. osvaldoi because they ‘probably belong to the same species as represented by the bones from Pinar del Río [west Cuba], which cannot be referred to any known species of owl, living or fossil’ (Arredondo & Olson 1994: 436).
I have now had the opportunity to study fossil and living Strigiformes from the West Indies (Olson & Suárez 2008, Suárez & Olson 2015, 2020) for some years, and have collected and examined material pertaining to Ornimegalonyx in Cuba (see, for example, Alegre 2002, Suárez 2020), as well as the type material of Bubo osvaldoi including specimens at the Museo Nacional de Historia Natural de Cuba (MNHNCu), La Habana. After comparisons with living and extinct taxa, including Bubo, I have discovered that the type series of B. osvaldoi is a composite, comprising two different large strigid owls that are similar in size. The holotype of B. osvaldoi, a right tarsometatarsus (MNHNCu 75.27.1), and two topotypical paratypes (cited here with their original numbers), a femur (MNHNCu 75.27.3) and a shaft of tarsometatarsus (MNHNCu 75.27.2), are from western Cuba, assigning the name Bubo osvaldoi to that form. However, the two remaining USNM bones, from the eastern extreme of the archipelago, belong to a species that agrees with Ornimegalonyx and differs from Bubo Duméril, 1805, by the following qualitative characters (see Arredondo & Olson 1994: figs. 2A, 3A–D; Fig. 1): (1) humerus small, having (2) shaft (palmar and / or anconal aspect) thinner proximally (also unlike large extinct Tytonidae), with (3) marked curvature and (4) impression of brachialis anticus reduced; femur (anterior and / or posterior aspect) with (5) shaft wider at ends (less expanded in Bubo), (6) anterior intermuscular line crossing (transversal) completely the anterior face of the shaft, from proximal (more lateral) to distal (medial) margins of the bone, not parallel with borders of the shaft (parallel, or almost parallel in Bubo), (7) anterior face of the shaft very flat above condyles (more rounded or convex in Bubo; some characters, including this one, were incorrectly depicted in Arredondo & Olson 1994: fig. 3), (8) rotular groove extremely wide, with condyles placed far apart (closer together in Bubo), and (9) external condyle bent laterally (not, or less bent in Bubo).
Measurements (mm) of the holotype femur of Ornimegalonyx ewingi sp. nov. (USNM 447022) compared to those of the type species of the genus, O. oteroi. Measurements by WS unless otherwise stated. Sequence: range (mean, sample size).
I was unable to detect any diagnostic character, or distinction, between the highly variable material of O. oteroi (with chronoclines at some localities; WS unpubl.) and specimens of the other three species described in the genus (see Arredondo 1982: 45–47). But all of the material agrees in intraspecific variation observed in skeletons of modern Strigidae. The most enigmatic of the extinct taxa is O. minor, of which the type material, two fragmentary proximal femora (Arredondo 1975: fig. 9; 1982: fig. 14), was unavailable to me until recently. These fossils were sent to B. Patterson at the Museum of Comparative Zoology (MCZ), Harvard Univ., MA, by O. Arredondo (see Arredondo 1975: 139). Thanks to S. L. Olson, this material and that of other Cuban taxa at MCZ, were sent on loan to USNM, were I examined it. No differences other than sexual were observed in O. minor, of which material named by Arredondo appears to represent the male (smaller sex) of O. oteroi. The holotype, a proximal right femur (SEC P-37), is the smaller of the two specimens, and Arredondo (1982: table 6) estimated its total length at 130 mm. The paratype, a proximal left femur (SEC P-38), is larger than the holotype, with a fractured trochanter. This fragment of bone is similar in size to other specimens previously identified by Arredondo (in some cases in my company) as O. oteroi; but its measurements (see Table 1) were not included in the original description of O. minor. If we take the above-mentioned estimated length of the holotype of O. minor as correct, which persuaded Arredondo to describe it as a new species, we have a strigid too large for the Ornimegalonyx material previously included within Bubo osvaldoi (see Table 1).
In conclusion, of the species previously referred to Ornimegalonyx only O. oteroi Arredondo, 1958a, is valid; the other three described by Arredondo (1982) are junior subjective synonyms. The much smaller species Bubo osvaldoi Arredondo & Olson, 1994, is represented solely by material from the type locality in Pinar del Río in western Cuba, whereas two other specimens from its type series, collected in eastern Cuba, are representative of a previously undescribed Ornimegalonyx, as diagnosed above. This is named below, in the following taxonomic arrangement:
Family STRIGIDAE Leach
Genus Bubo Duméril, 1815
Bubo osvaldoi Arredondo & Olson, 1994
Bubo osvaldoi Arredondo & Olson, 1994 (part), Proc. Biol. Soc. Wash. 107: 438.
Tyto riveroi: Salgado et al. 1992: 28, table 1.
Holotype.—Right tarsometatarsus lacking proximal end, MNHNCu 75.27.1 (see Arredondo & Olson 1994: fig. 1B–D).
Paratypes.—Complete right femur without internal condyle, abraded about the trochanter, MNHNCu 75.27.3 (see Arredondo & Olson 1994: fig. 2B) (Fig. 1D); shaft of left tarsometatarsus without proximal portion and digital trochleae, MNHNCu 75.27.2 (not illustrated).
Type locality.—All of the above material is from Cueva del Mono Fósil, Sierra de Galeras, municipality of Viñales, Pinar del Río province, western Cuba. This is the type locality of Paralouatta varonai Rivero & Arredondo, 1991.
Distribution.—Restricted to the type locality in western Cuba (see above).
Remarks.—The humerus of Bubo osvaldoi is unknown, as USNM 447023, described as a paratype in the original description, represents a new taxon described below. The species is a large Bubonini, similar in size to female B. bubo Linnaeus, 1758 (see descriptions in Arredondo & Olson 1994).
Genus Ornimegalonyx Arredondo, 1958a (type, by monotypy [contra Brodkorb 1961], O. oteroi Arredondo)
Ornimegalonyx oteroi Arredondo, 1958a
Ornimegalonyx oteroi Arredondo, 1958a, El Cartero Cubano 17(7): 11.
Ornimegalonyx acevedoi Arredondo, 1982: 45, new synonymy (type locality ‘Cueva de Quinto, Boca de Camarioca, Matanzas’ province, Cuba).
Ornimegalonyx minor Arredondo, 1982: 46, new synonymy (type locality ‘Cueva de Paredones, San Antonio de los Baños [= Caimito], Habana’ [= Artemisa] province, Cuba).
Ornimegalonyx gigas Arredondo, 1982: 47, new synonymy (type locality ‘Cantera de los Hornos de Cal, a unos 4 km al este de la ciudad de Sancti Spíritus’, Sancti Spíritus province, Cuba).
Type locality.—Cueva de Pío Domingo, Sierra de Sumidero, Ensenada de Pica Pica, Pinar del Río province, Cuba. This is the type locality of other Cuban extinct birds, including Antigone cubensis (Fischer & Stephan 1971a) and Nesotrochis picapicensis (Fischer & Stephan 1971b).
Emended diagnosis.—The largest species of the genus Ornimegalonyx.
Remarks.—Treatment of the names arredondoi and borrasi (see Arredondo 1958a: 11; 1964: 21) as nomina nuda, in the synonymy of Ornimegalonyx oteroi (Arredondo 1975: 145) or O. acevedoi (Arredondo 1982: 46), are incorrect. In the original description of O. oteroi, Arredondo (1958a: 11), in reference to arredondoi stated: ‘nombre que ahora declino y propongo el de Oteroi’ [= ‘a name that now I reject and propose that of Oteroi’]. As arredondoi was not validly introduced when first published (Arredondo 1958a), it is not made available there (ICZN 1999, Art. 11.5). Brodkorb (1961) treated it, incorrectly, as an available name, but as a synonym of oteroi. Thus, the name arredondoi is not available (ICZN Art. 11.6). On the other hand, borrasi was mentioned only conditionally by Arredondo (1964: 21): ‘parece tratarse de otra especie, que de lograrse la certeza, llevaría el nombre específico de “Borrasi”...’ [= ‘it seems to be another species, which if proven, would bear the specific name “Borrasi”...’]. Therefore borrasi too is not available (ICZN Art. 15.1), but was cited subsequently by Acevedo (1965: 21) for a bird that was never described by Arredondo. The same fossils, to which those names were applied, were explicitly treated as O. oteroi by Arredondo (1975), and not mentioned in Arredondo (1984).
Ornimegalonyx ewingi sp. nov.
Bubo osvaldoi: Arredondo & Olson, 1994: 438 (part).
Type locality.—A ‘mine’ in the vicinity of Baire, Oriente (= Santiago de Cuba) province, Cuba. The age of both the holotype and paratype, and the precise location of the type locality are unknown. Probably they were collected at the same time as mammal material known from this locality (see Arredondo & Olson 1994: 438). According to Mayo (1980: 223, 225), the ‘mine’ is in the south of the former Oriente province, and probably a cave (but see Aguayo & Howell Rivero 1955). It is also the type locality of the extinct sloth Neocnus baireiensis Mayo, 1980.
Distribution.—Known only from the type locality in eastern Cuba (see above).
Diagnosis.—A diminutive species of Ornimegalonyx, slightly larger than Bubo osvaldoi.
Etymology.—I take great pleasure in dedicating this new species to my close friend and colleague Dr Gil C. Ewing, in recognition of his great knowledge and passion for birdlife.
Description and comparisons.—Differs from O. oteroi by its much smaller size (c.30% smaller), with femur shaft more columnar, less constricted bilaterally at the midpoint, and flaring less at both ends. Humerus relatively more robust, with shaft shorter, less curved and more expanded at the distal end; impression of brachialis anticus relatively larger, less vertical, and more distally placed; entepicondylar prominence less projected. For additional comparisons and descriptions, see Arredondo & Olson (1994).
Remarks.—The type series of O. ewingi represents the first material pertaining to the genus to be collected (probably pre-1942, see Aguayo 1950). Given its size, the species' prey must have been smaller compared to those of its gigantic congener. Some specimens from the tar seeps Las Breas de San Felipe, Matanzas province, Cuba (Suárez 2020: 32), may also be referrable to this taxon, but additional comparison and study is needed to clarify their identity.
I thank Storrs L. Olson for making available critical fossil specimens. An early version of the manuscript was reviewed by Philip Reese. Gary Graves (USNM) and Rick Hochberg (Proceedings of the Biological Society of Washington) provided assistance with pertinent material and permissions necessary for reproducing Fig. 1. William Suárez Jr. further assisted with its preparation. The manuscript benefitted substantially from critical revisions by Steven D. Emslie and Lázaro W. Viñola. I express my gratitude to Guy Kirwan for his constant help with this manuscript. Nomenclature in this paper was reviewed by Dick Schodde and Vítor Piacentini on behalf of the Working Group on Avian Nomenclature of the International Ornithologists' Union.