2 new genera and 3 new species of Picidae (2 Viewers)

[Fred Ruhe]

Kenneth E. Campbell, Jr. & Zbigniew M. Bochenski, 2021

A review of the woodpeckers (Aves: Piciformes) from the asphalt deposits of Rancho La Brea, California, with the description of three new species

Palaeobiodiversity and Palaeoenvironments. in press.
doi:10.1007/s12549-020-00444-1

Abstract: https://link.springer.com/article/10.1007/s12549-020-00444-1

A review of the piciform avifauna from the upper Pleistocene asphalt deposits of Rancho La Brea, Los Angeles, California, reveals that it comprises at least six species in five genera. We describe a new genus and species, Breacopus garretti, for the largest woodpecker, which was similar in size to the largest living North American species, Dryocopus pileatus. We recognise a new genus and species, Bitumenpicus minimus, for the smallest woodpecker in the palaeoavifauna of Rancho La Brea. We also recognise a new species of Melanerpes, M. shawi. The most common species present in the asphalt deposits is the Northern Flicker, Colaptes auratus, which is predictable because of its ground-foraging habits, which would bring it into contact with the surficial seeps of petroleum more often than those piciforms preferring an arboreal habitat. Habits of the extant species from Rancho La Brea suggest a primarily open environment, with the largest species suggesting the presence of at least scattered large trees. The piciform palaeoavifauna provides support for the hypothesis that southwestern California was a “biogeographic island,” or a region where the insular nature of the habitat promoted speciation during the late Pleistocene.

Enjoy,

Fred

 

[Fred Ruhe]

Systematic Palaeontology

Class Aves Linnaeus, 1758
Order Piciformes Meyer and Wolf, 1810
Family Picidae Vigors, 1825
Genus Breacopus gen. nov.

Type species: Breacopus garretti sp. nov., monotypic.

Differential diagnosis: Holotypic carpometacarpus differs from that of the Recent genera Dryocopus Boie, 1826 and Campephilus, which include the largest woodpeckers in the world, by having (1) Trochlea carpalis with slightly abraded distal portion of dorsal rim not deeply undercut on ventral side, thereby giving a gradual transition, in proximal view, between posterior ends of dorsal and ventral trochlear rims (dorsal rim deeply undercut, giving a notched appearance in proximal view in Dryocopus and Campephilus); (2) Trochlea carpalis with dorsal rim, in dorsal view, broader at base and more rounded proximally than in Dryocopus and Campephilus; (3) attachment site for Lig. ulnocarpo-metacarpale ventrale deep, with distal rim more prominent, curving strongly posteriad distally, and ending well proximal to Spatium intermetacarpale (in Dryocopus and Campephilus the ridge curves less distally and ends closer to the Spatium intermetacarpale); (4) Synostosis metacarpalis proximalis extends distinctly farther distad (i.e. is longer) than in Dryocopus and Campephilus (Fig. 1); (5) Facies articularis digitalis major, in distal view, less pronounced ventrad, which results in a dorsoventrally relatively narrower Facies articularis digitalis major than in Dryocopus and Campephilus; and (6) Spatium intermetacarpale distinctly broader for length, of more uniform width, with broad U-shaped distal end, in ventral view (narrower for length in Dryocopus and Campephilus, with distal end a narrower U-shape).
Although the shape of the Processus intermetacarpalis appears distinctly different in Fig. 1, in dorsal view, some of this difference is a result of abrasion of its posteroproximal edge. In ventral view, the ventral aspect of the Spatium intermetacarpale is clearly broader for length.

Etymology: Brea, after its occurrence in the asphalt deposits of Rancho La Brea; copus, after Greek kopus, “beating.” Gender, masculine.

Breacopus garretti sp. nov.

Holotype: Carpometacarpus. Nearly complete, left, lacking distal portion of Os metacarpale minus, LACM RLB H3605

Type horizon: Rancho La Brea asphalt deposits; upper Pleistocene

Holotype: Carpometacarpus. Nearly complete, left, lacking distal portion of Os metacarpale minus, LACM RLB H3605

Type horizon: Rancho La Brea asphalt deposits; upper Pleistocene

Type locality: Pit 16, Rancho La Brea, Los Angeles, California, USA.

Referred material: Distal left tibiotarsus with shaft (proximal endmissing), LACMRLB L776, Pit A of Bliss 29, Rancho La Brea asphalt deposits, Los Angeles, California, USA.

Dfferential diagnosis: As for genus.

Etymology: We name this species for Kimball L. Garrett, Collections Manager, Department of Ornithology, Natural History Museum of Los Angeles County, in recognition of his decades of service building the modern avian comparative osteology collection at the Museum, without which the identification of many taxa from the Rancho La Brea deposits would not be possible.

Comment: Breacopus garretti is the second large woodpecker to be described from the upper Pleistocene of North America, Campephilus dalquesti Brodkorb, 1971 being the first. Unfortunately, C. dalquesti is known only from a fragmentary distal tarsometatarsus, so it is not possible to compare it directly to the two specimens of B. garretti. However, morphologically, B. garretti is closer to Dryocopus than Campephilus, so if the assignment to genus of C. dalquesti is correct, B. garretti is unlikely to be closely related to C. dalquesti. Although the specimens were not compared to comparable bones of the Ivory-billed Woodpecker, Campephilus principalis (Linnaeus, 1758), the largest known North American woodpecker, the generic differences noted between Breacopus and the species of Campephilus available are sufficient to discount the possibility that Breacopus represents the Ivory-billed Woodpecker. Further, the preference of the Ivory-billed Woodpecker for old-growth forest stands in the southeastern United States and northeastern Mexico would make it unlikely that it would appear in semi-arid southwestern California. Specimens identified as possibly of the Pileated Woodpecker were reported from cave deposits in the eastern United States by Shufeldt (1897) and Goslin (1955). The former specimen was a well-worn ulna, and the latter reference did not indicate which bones were seen.


Fig. 1 Stereopairs of the holotypic left carpometacarpus of Breacopus garretti gen. et sp. nov. (LACM RLB H3605), late Pleistocene, Pit 16, Rancho La Brea, California, USA (a) and a comparative left carpometacarpus of Dryocopus pileatus (LACM 115893), Recent, western North America (b), in dorsal (a1, b1) and ventral (a2, b2) views.
Abbreviations: alu attachment site for Lig. ulnocarpometacarpale ventrale; fam Facies articularis digitalis major; fit Fossa infratrochlealis; oma Os metacarpale majus; omi Os metacarpale minus; pe Processus extensorius; pi Processus intermetacarpalis; si Spatium intermetacarpale; smd Synostosis metacarpalis distalis; smp Synostosis metacarpalis proximalis; tcd Trochlea carpalis (dorsal rim); tcv Trochlea carpalis (ventral rim). Scale bar = 10 mm

 

[Fred Ruhe]

Genus Melanerpes Swainson, 1837

Comment: The genus Melanerpes is represented in North America by six species: M. lewis (Lewis’ Woodpecker), M. erythrocephalus (Linnaeus, 1758) (Red-headed Woodpecker), M. formicivorus (Acorn Woodpecker), M. uropygialis (Gila Woodpecker), M. aurifrons (Wagler, 1829) (Golden-fronted Woodpecker), and M. carolinus (Linnaeus, 1758) (Red-bellied Woodpecker). Of these, only M. lewis, M. formicivorus, and M. uropygialis have a modern range that includes California. Of the latter three, M. lewis is by far the largest and its skeletal elements can be separated from the other two on the basis of size. Melanerpes lewis also is larger than the other three North American species of the genus not occurring in California today. Melanerpes lewis is fairly common in the Rancho La Brea collections, being represented by 92 specimens from at least 18 individuals. We did not record any specimens of the smaller species of Melanerpes from the Rancho La Brea collections, although specimens of smaller sized species of other genera were found. Also, Miller (1929) did report the presence of M. formicivorus from Rancho La Brea in the UCMP collections, but we could not confirm its presence. In addition to the living M. lewis, we found a number of specimens of an extinct species referable to the genus Melanerpes and comparable in size to M. lewis, which we describe here.

Melanerpes shawi sp. nov.

Holotype: Tarsometatarsus. Complete, right. LACM RLB L530.

Type horizon: Rancho La Brea asphalt deposits; upper Pleistocene.

Type locality: Pit A of Bliss 29, Rancho La Brea, Los Angeles, California USA.

Differential diagnosis: The holotypic tarsometatarsus of M. shawi is distinguished from that of M. lewis, whose size range it falls within, by having (1) Eminentia intercondylaris taller, more slender, with smaller base, in anterior view; (2) Cotyla lateralis with posterolateral extension shorter, in proximal view; (3) Hypotarsus extending less laterad, in proximal view; (4) Trochlea metatarsi IV shorter anteroposteriorly and lacking a distal projection; (5) Trochlea accessoria with anterior edge partly hidden behind Trochlea metatarsi III, in anterior view (anterior edge clearly visible between Trochlea metatarsi III and IV in M. lewis).

Etymology: We name this species for Christopher Shaw, former Collections Manager and volunteer at the Rancho La Brea tar pits, to honour his many decades of service and dedication to the preservation and study of the palaeontological resources of Rancho La Brea.

Referred material: [All catalogue numbers preceded by acronym LACM RLB.] Complete right scapula, L707; humeral end left coracoid, L696; complete left humerus, F9756; complete left (2) and right ulnae, G8812, L627, G8821, respectively; proximal right ulna, R14745; distal right radius, R35971; complete right and left carpometacarpi, L602, L589, respectively; complete left femur, L755; almost complete right tibiotarsus, L719; complete right (2) and left tarsometatarsi, G5656, P23–7332, and R12358, respectively; proximal right and left tarsometatarsi, L771 and R14313, respectively. The 18 specimens give a minimum number of four individuals.

Comment: The characters distinguishing Melanerpes shawi apply equally well to both Recent and fossil specimens of M. lewis.


Fig. 2 Stereopairs of the holotypic right tarsometatarsus of Melanerpes shawi sp. nov. (LACM RLB L530), late Pleistocene, Pit A of Bliss 29, Rancho La Brea, California, USA (a) and a comparative right tarsometatarsus of Melanerpes lewis (LACM 102440), Recent, western North America (b), in anterior (a1, b1), posterior (a2, b2), proximal (a3, b3), and distal (a4, b4) views. Abbreviations: ctl Cotyla lateralis; ei Eminentia intercondylaris; hy Hypotarsus; ta Trochlea accessoria; tm III Trochlea metatarsi III; tm IV Trochlea metatarsi IV. Scale bar = 10 mm

 

[Fred Ruhe]

Melanerpes lewis (Gray, 1849)

Referred material: Melanerpes lewis is represented by 89 specimens, representing a minimum of 19 individuals. Online Resource 1 presents a complete listing of all specimens referred to this taxon. In addition, four other specimens were referred to Melanerpes sp. cf. M. lewis.

Small woodpeckers of Rancho La Brea

There are two modern genera comprising very small woodpeckers in North America: Dryobates and Sphyrapicus Baird, 1858. The former has nine species, three of which include southwestern California in their modern range and could be expected to have occurred in the Los Angeles Basin in the Pleistocene: D. villosus, D pubescens, and D. nuttallii. Dryobates villosus is the largest of the three, and D. pubescens is the smallest North American woodpecker. Dryobates nuttallii is separable from both by size. Howard (1962) listed one individual of Dryobates sp., but no specimen of that genus was listed in the catalogue. We did not find any specimens that we could refer to Dryobates.
The genus Sphyrapicus comprises four species, although there is some disagreement as to the validity of each because three of the four are said to interbreed (Johnson and Johnson 1985; Seneviratne et al. 2016, and papers cited therein). Only one of the four, S. ruber, includes southwestern California in its modern range. Brodkorb (1971a, b) listed S. varius as being recorded from Rancho La Brea, citing Howard (1962), although she listed only Sphyrapicus sp. in her report. Specimens of S. ruber are slightly larger than those of D. nuttallii. We present characters distinguishing the two species when appropriate. We describe a new genus and species of a third small woodpecker similar in size to Dryobates nuttallii on the basis of osteological characters.

Genus Sphyrapicus Baird, 1858
Sphyrapicus ruber (Gmelin, 1788)

Referred material: We identified 26 specimens, representing a minimumof four individuals, as Sphyrapicus ruber. A list of the referred specimens is presented in Online Resource 1. Howard (1962) listed one individual as Sphyrapicus sp. in her report. Three specimens of Sphyrapicus sp. were previously recorded in the catalogue (LACMRLB F9985, G97 and G5663), but only the first two of the three could be located. We identified F9985 as S. ruber, but we determined that G97 could not be positively identified to species.

Comment: Of the four species of Sphyrapicus that occur in North America, the one species most likely to have occurred in southern California in the Pleistocene, and the only one to inhabit the region today, is Sphyrapicus ruber.

Genus Colaptes Vigors, 1825
Colaptes auratus (Linnaeus, 1758)

Referred material: Howard (1962) referred to Colaptes auratus 18 individuals based on 60 catalogued specimens and an unknown number of uncatalogued specimens. We add to that number 257 additional specimens for a total of 317 specimens representing a minimum of 38 individuals. The small increase in individuals, as opposed to the large increase in specimens, is attributed to the readily recognisable, based on morphology, but uncatalogued, tarsometatarsi from Pit A being included in Howard’s tabulation, whereas the remainder of the elements from that highly productive sitewere not identified to species. In addition to the specimens identified to species, four carpometacarpi were referred to cf. Colaptes sp. No morphological characters separated the fossil specimens of C. auratus from Recent comparative material of C. auratus. For a complete listing of all specimens of Colaptes auratus, see Online Resource 1.

 

[Fred Ruhe]

Genus Bitumenpicus gen. nov.

Type species: Bitumenpicus minimus sp. nov., monotypic.

Differential diagnosis: The holotypic tarsometatarsus differs from that of species of Sphyrapicus and Dryobates by having (1) Facies dorsalis flatter and relatively wider; (2) Shaft more robust (Figs. 8 and 9), with medial side straighter, less curving leading to Trochlea metatarsi II; (3) Eminentia intercondylaris with lateral side only slightly curved, in posterior view; (4) Crista lateralis hypotarsi with posterior terminus not curving mediad (shorter and much wider in Sphyrapicus); (5) Sulcus hypotarsi broader, in proximal view; (6) Trochlea metatarsi II with slightly abraded tip, but directed more mediad than posteriad, not projecting distad beyond medial rim of Trochlea metatarsi III; (7) Trochlea metatarsi IV with posterior portion only slightly extending laterad beyond base, with medial edge closer to lateral edge of Trochlea III; and (8) Trochlea accessoria not extending as far distad, in anterior view, and with more slender base.

Etymology: Bitumenpicus, from Latin bitumen, asphalt; picus, woodpecker; in reference to the deposits in which it was discovered. Gender, masculine.

Bitumenpicus minimus sp. nov.

Holotype: Tarsometatarsus, Complete, left. LACM RLB L552

Diagnosis: As for genus.

Type horizon: Rancho La Brea asphalt deposits; upper Pleistocene.

Type locality: Pit A of Bliss 29, Rancho La Brea asphalt deposits, Los Angeles, California, USA.

Etymology: minimus, Latin, in reference to it being the smallest woodpecker known from Rancho La Brea.

Referred material: [All catalogue numbers preceded by acronym LACMRLB.] Complete left humerus, L575, proximal end right ulna, L674; distal end left ulna, L679; complete left radius, L769; one proximal right and one distal left radius, L770, PMS3725, respectively; right carpometacarpus, L615. All referred specimens are from Pit A of Bliss 29 of the Rancho La Brea asphalt deposits. The eight specimens represent a minimum of one individual.

Small Piciformes indet.

In addition, we found in the collection eight specimens of a size similar to Sphyrapicus, but they can only be identified as small Piciformes indet. They are complete humerus (G97); distal right (L617, R62398) and distal left (R66124) carpometacarpi; proximal left (R61565), distal right (L526), and distal left (L522, MT31) tarsometatarsi. [All catalogue numbers preceded by acronym LACM RLB.]

Fred

Fig. 3 Stereopairs of the holotypic left tarsometatarsus of Bitumenpicus minimus gen. et sp. nov. (LACM RLB L575), late Pleistocene, Pit A of Bliss 29, Rancho La Brea, California, USA (a) and a comparative left tarsometatarsus of Dryobates nuttallii (LACM 102460), Recent, western North America (b), in anterior (a1, b1) and posterior (a2, b2) views. Abbreviations: clh Crista lateralis hypotarsi; ei Eminentia intercondylaris; sh Sulcus hypotarsi; ta Trochlea accessoria; tm II Trochlea metatarsi II; tm III Trochlea metatarsi III; tm IV Trochlea metatarsi IV. Scale bar = 10 mm.