Xestospiza fastigialis (Ridge-billed Finch)

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Xestospiza fastigialis
Olson & James 1991
Holocene of Oahu and Molokai, Hawaiian Islands
Primary materials: Holotype: incomplete skeleton
Secondary materials: Paratypes: maxilla, mandibulae, fragment of sternum, synsacrum, right coracoïd, left scapula, left ulna, left carpometacarpus, pelvis, femora, tibiotarsi and tarsometatarsus

Storrs L. Olson & Helen F. James,
Descriptions of thirty-two new species of birds from the Hawaiian Islands: Part II. Passeriformes
Ornithological Monographs 46 (1991)
The American Ornithologists' Union, Washington D.C.

[Melanie]

Ridge-billed finch

Storrs Olson and Helen James have described a new Genus of birds, Xestospiza, based on fossils recovered from Barbers Point, Oahu and other locations in the Hawaiian Islands. One of the two new species in this Genus, Xestospiza fastigialis, once occurred on Oahu. According to Olson and James," Members of this genus are set apart from the other finch-billed drepanidines by their cone-shaped rather than arched bills. The genus most closely resembles Melamprosops."

In Description of Thirty-Two New Species of Birds From the Hawaiian Islands: Part II Passeriformes, they note: " In general bill shape, X. fastigialis has an icterid-like aspect that is particularly reminiscent of cowbirds (Molothrus)..." " Fossils of X. fastigialis occur commonly on the three adjacent islands of Oahu, Molokai, and Maui, making this the most widely-distributed of the new fossil species." This species possibly occurred on all six major Hawaiian islands. Storrs Olson and Helen James conclude this new species description by writing: " The disappearance of X. fastigialis throughout its entire range serves as a reminder that extinction affected broadly distributed species along with the more restricted ones."

[another specialist]

info above came from www.oahunaturetours.com/xestospiza.html

[Deleted]

Hi !

Here is a pic, only a scetch ...:



Bye
Alex

[another specialist]

xestospiza fastigialis
New Species


EXTINCT


A new species described from incomplete skeletons collected at Crystal Cave, Manawainui Gulch, Maui, Barbers Point and Ulupau , Oahu and Moomomi ,Molokai. Described as a finch with a cone-shaped bill.The body size is in the range of Telespiza ultima.In general bill shape, X. fastigialis is icterid like.

Fossils of X. fastigialis occur commonly on the three adjacent islands of Oahu,Molokai and Maui,making it the most widely-distributed of the new fossil species.


www.oahunaturetours.com/xestospiza.html

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source for my first entry

www.ornitaxa.com/SM/Fossil/FossilFringilli.htm

[another specialist]

Xestospiza, new genus
Type species: Xestospiza fastigialis, new species.
Included species: Xestospiza fastigialis, new species, Xestospiza conica, new
species.
Distribution: Kauai, Oahu, Molokai, and Maui.
Etymology: Greek, xestos, planed, scraped, plus spiza, a finch; from the shape
of the maxilla, which gives the appearance of having been planed to a straight
profile, and in one species has a distinctly flattened dorsal surface. The gender is
feminine.
Diagnosis: Members of this genus are set apart from the other finch-billed
drepanidines by their cone-shaped rather than arched bills. The dorsal profile of
the maxilla is straight or nearly straight as opposed to distinctly curved as in all
other finch-billed drepanidines. The bill is relatively long and narrow and the
nafial openings are slightly elongated anteroposteriorly compared to the drepanidine
finches with heavier, arched bills (Telespiza, Rhodacanthis, Chloridops, and
Orthiospiza).
This genus most closely resembles Melamprosops, but differs in having a sturdier
dorsal nasal bar, the maxilla deeper below the nafial openings, a shallower roedial
groove and more pronounced ventral ridges, and a less deeply V-shaped posteroventral
contour of the maxilla, in addition to having a conical bill.
Remarks: Because one of the new species incIuded in Xestospiza is known only
from a pair of maxillae, we have limited the generic diagnosis to characters of
that element.
The conical rather than arched bill of this finch-like genus stretches the morphological
breadth of the drepanidine radiation in a new direction. Finches with
conical bills were widespread in the prehuman avifauna of the archipelago, as
they occur on every island with a significant passefine fossil record.
Although not necessarily each other's closest relatives, Xestospiza, Melamprosops,
and Psittirostra represent a similar grade of evolution within the drepanidine
radiation in that each combines a finch-like bill shape with a few characters that
are derived relative to the other finch-billed taxa. The morphological distance
between Xestospiza and Melamprosops is not great, so that we were at first inclined
to include the new species in the latter, to avoid introducing a new genus. We
reconsidered when it proved that the only characters shared by the three species
are ones that we would interpret as primitive.

[another specialist]

Xestospi•a fastigialis, new species
(Figs. 22D-F, 23B, C, E, F, 24)
"cf. Psittirostra, ridge-billed finch" Olson and James, 1982b:40.
"Psittirostra (subgenus incertae sedis) Ridge-billed finch" Olson and James, 1982b:45;
1984:771.
"Ridge-billed Finch" James, 1987:225.
Holotype: Incomplete skeleton, USNM 445821. Collected 4 April 1988 by
Storm L. Olson, Pauline Fiene-Severns, R. Michael Severns, and Thomas W.
Stafford, Jr. The specimen consists of the maxilla (Fig. 24D-F), the mandible
lacking a portion of the left ramus (Fig. 24A, C), a substantial fragment of the
cranium (Fig. 24B), a fragment of the sternum preserving the manubrial spine
and coracoidal sulci, part of the synsacrum, ten vertebrae, the dorsal half of both
coracoids, the sternal end of the left coracold, the anterior half of the right scapula,
the left scapula, the distal half of the right humerus, the left humerus (Fig. 24G),
both ulnae (Fig. 24H), the proximal end of the right carpometacarpus, the left
carpometacarpus (Fig. 24I), the left femur (Fig. 24J), the right tibiotarsus (Fig.
24K), the proximal end of the left tibiotarsus, the right tarsometatarsus (Fig. 24L),
and a piece of the shaft of the left tarsometatarsus.
Type locality: Crystal Cave (183 m), Manawainui Gulch, Maui, Hawaiian Islands.
Distribution: Oahu: Barbers Point and Ulupau Head. Molokai: Moomomi dunes
and Ilio Point. Maui: Puu Naio Cave, Lua Lepo, and Crystal Cave.
Etymology: An adjective based on Latin, fastigium, a slope up or down to a
point, a gable; from the shape formed by the converging ridges that ascend along
the dorsal nasal bar in this species.
Measurements (ram) of holotype: Length measurements, with the comparable
measurement from Telespiza ultima (female, MVZ 124729) in parentheses: basitemporal
plate plus the occipital condyle, 4.8 (4.9); humerus, 17.4 (16.4); ulna,
17.5 (19.3); carpometacarpus, 9.9 (11.3); femur, 17.7 (16.9); tibiotarsus without
the cnemial crest, 29.0 (28.8); tarsometatarsus, 21.3 (21.7). For additional measurements
of holotype, see Tables 9 and 10.
Paratypes: Oahu, Barbers Point: complete maxilla, USNM 322483; three slightly
damaged mandibles, USNM 445799 (Fig. 23B, E), BBM-X 155522, and BBM-X
155728.
Molokai, Ilio Point: ' Complete maxilla, BBM-X 178142.
Maui, Crystal Cave, Manawainui Gulch: Partial skeleton, USNM 394085,
consisting of the mandible lacking the posterior part of the left ramus (Fig. 23C,
F), the basitemporal plate, a fragment of the sternum, the synsacrum, partial right
coracoid, partial left scapula, distal end of left ulna, left carpometacarpus, two
pelvic fragments including the acetabula, both femora and tibiotarsi, all somewhat
damaged, and the left tarsometatarsus lacking the proximal end. Puu Naio Cave:
complete maxilla with the frontal attached, USNM 445800 (Fig. 22D-F); slightly
damaged mandible, USNM 445805; right quadrate lacking part of the orbital
process, USNM 445801; left quadrate, USNM 445802.
Measurements (ram) ofparatypes: Associated skeleton, USNM 394085: Cranium:
length of basitemporal plate plus the occipital condyle, 4.8. Mandible:
length, 21.1 (about 1.6 mm missing from the tip); height of symphysis, 2.9; width
of articular end with medial process, 3.9; height at lateral cotyla, 1.8; height at
the angle of the mandible, 4.0; length of ramus (middle part), 9.4. Carpometacarpus:
length, 9.7. Synsacrum: ventral length, 13.5. Femur: length, 17.4. Tibiotarsus:
length without cnemial crest, 28.8. Tarsometatarsus: estimated length,
20.2. For additional measurements of paratypes, see Tables 9 and 10.
Diagnosis: A finch with a cone-shaped bill, distinguished from other drepanidines
by the two converging, rugose ridges that ascend along the dorsal nasal bar
of the maxilla. Between these ridges, the dorsal surface of the nasal bar is fiat in
cross-section, whereas this surface has a convex cross-section in other drepanidines
except the long, thin-billed Aidemedia lutetiae, new genus and species. The ventral
surface of the maxilla has a shallow medial trough and ventral ridges that are
moderately developed posteriorly but become indistinct about three-quarters of
the distance to the tip of the bill. This is in contrast to X. conica, which has a
distinctly deeper medial trough and shorter ventral ridges.
The mandible lacks retroarticular processes and in this and other respects is
typically finch-like, with a thick-walled symphysis and a deep ramus, particularly
at the angle of the mandible. However, the symphysis is relatively long and narrow
and the articular end of the mandible is relatively small compared to other finchbilled
drepanidines. The small lateral cotylae are slightly elevated and angled
posteromedially. The middle part of the ramus is relatively short compared to
Loxioides, Psittirostra, and Melamprosops, and in this respect is closer to the
condition in the heavier-billed finches.
The quadrate has the form typical of finch-billed drepanidines, with a stout
body and a rounded medial condyle.
In the holotype, the walls of the interorbital septurn are fused to form a single
sheet of bone, as opposed to being entirely separated by an intervening network
of trabeculae as they are in finch-billed drepanidines with heavier beaks such as
the similar-sized T. ultima. The septurn is thus relatively weak and may even
have been fenestrated in the missing anterior portion, as it sometimes is in
Melamprosops phaeosoma, a bird with similar development of the interorbital
septum.
Remarks: The body size is in the range of Telespiza ultima, although the distal
wing elements may be somewhat reduced by comparison (see measurements of
holotype).
In general bill shape, Y(. fastigialis has an icterid-like aspect that is particularly
reminiscent of cowbirds (Molothrus). Y(. fastigialis differs from Molothrus and
other icterids in lacking a distinctive flange on the tomium of the mandible.
Although the size of the skull in Y(. fastigialis is roughly the same as in M. ater,
the interorbital septum is much less extensively fenestrated, with the optic foramen
not connected anteriorly to an interorbital fenestra as in M. ater. Furthermore,
the portion of the cranial fenestra that is preserved in the holotype shows a broad,
flat posteroventral surface, as opposed to the blade-like, mounded surface seen
in M. ater. These traits of the cranial fenestra and interorbital septum argue that
Y(. fastigialis is a cardueline, not an icterid (Zusi 1978). Convergence of drepanidine
bill morphology toward that oficterids is also exhibited by the new genus of thinbilled
gaping birds, Aidemedia, and by Loxops sagittirostris.
Fossils of Y(. fastigialis occur commonly on the three adjacent islands of Oahu,
Molokai, and Maui, making this the most widely-distributed of the new fossil
species. Possibly its former distribution was similar to that ofPsittirostra psittacea,
Himatione sanguinea, and Vestiaria coccinea, which occurred historically on all
six of the larger islands without exhibiting geographic differentiation in phenotypic
characters. The disappearance of Y(. fastigialis throughout its range serves as a
reminder that extinction affected broadly distributed species along with the more
restricted ones.

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all from

elibrary.unm.edu/sora/om/om046.pdf.