Genus Thambetochen Olson and Wetmore, 1976
Type species:Thambetochen chauliodous Olson and Wetmore, 1976; by original
designation.
Included species: T. chauliodous Olson and Wetmore, 1976; T. xanion, new
species.
Distribution: Oahu, .Molokai, and Maul
Emended diagnosis:M oa-nalos differing from Chelychelynechenin that the
rostrum is not greatly vaulted and widened, and the occlusal surfaces of the
dentaries are not flattened but are ridged and bear well developed "teeth." Nostril
comparatively large, longer than high. Mandibular symphysis straight, coronoid
area not greatly expanded, lateral protuberance of coronoid reduced and more
ventrally situated, retroarticular process long and narrow.
Compared with Ptaiochen, the nostrils are situated farther posteriorly, with the
rostral tip anterior to the nostril being longer; the midline groove on the palatal
surface of the rostrum is deeper and wider; the prefrontals (lacrimals) are much
smaller; the roof of the orbits is expanded laterally and contains deep impressions
for the salt glands on the ventral surface; the temporal fossae and the scars for
attachment of the dorsal neck musculature are much more extensive, whereas the
scar for M. depressor mandibulae has become more elongate and narrow; the
overall outline of the cranium in lateral view is more flattened dorsally and in
posterior view is squared. The coracoid is proportionately shorter, more robust,
and has the sternal end much more expanded (not differing greatly from Chelychelynechenin
this respect).T he head of the femur is not angled as much proximally
and is more nearly on a level with the trochanter, and the fibula lacks a
distinct, squared crest on the anterior margin. The syringeal bulla is smaller and
differs in several qualitative features.
Thambetochen xanion, new species
(Fig. leA, C)
"Thambetochen sp." Olson and James, 1982b:34, 44; James, 1987:225, 226.
"Oahu Thambetochen sp." Olson and James, 1984:771.
Holotype.' Complete rostrum, USNM 389293 (Fig. leA, C). Collected 3 April
1980 by Storrs L. Olson, Helen F. James, Aki Sinoto, and Eric Komori.
Type locality.' Site 5e-Oa-B6-22, Barbers Point, Oahu, Hawaiian Islands.
Distribution: Oahu: Barbers Point and Ulupau Head.
Etymology: Greek, xanion, a comb, in reference to the appearance conveyed
by the bony tooth-like projections of the jaws. The name is a neuter noun in
apposition.
Measurements (mm) of holotype: Length from nasofrontal hinge to tip, 61.2;
height and width at posterior margin of nostril, 26.6 x 26.3; length of nostril,
15.2; least width of internarial bar, 5.3; length from anterior margin of nostril to
tip, 36.3.
Paratypes: Rostrum, USNM 426094; mandible, USNM 426095; cranium, BPBM
158859; right coracolds, USNM 426096, USNM 426097, BBM-X 156342; right
femora, USNM 426098, BBM-X 156365, BBM-X 156366; right tibiotarsi, BBM-X
156379, BBM-X 156381; left tibiotarsus, BBM-X 156380; right tarsometatarsus,
USNM 426099; right and left tarsometatarsi, USNM 389295.
Measurements (mm) ofparatypes: (These are in the same sequence as above.)
Rostrum: length from nasofrontal hinge to tip, 59.8; height and width at posterior
margin of nostril, 29.6 x 28.5; length of nostril, 15.5; least width of internarial
bar, 5.0; length from anterior margin of nostril to tip, 36.1. Cranium: length from
nasofrontalh inge, 61.5; greatestw idth (acrossp ostorbital processes)4, 6.6; width
across squamosals, 41.8; greatest horizontal diameter of orbit, 27.1. Mandible:
total length without retroarticular, 87.7; symphysis length, 22.9; greatest width
of dentary, 5.8; height at coronoid process, 17.0. Coracoid: length with sternal
end flat on calipers, 27.9, 26.7, 26.9; depth ofproximal end, 10.2, 9.3, 10.0; width
and depth of shaft just distal to glenoid facet, 5.3 x 5.2, 5.8 x 5.0, 5.3 x 4.8;
width at sternael nd, 23.8, 22.6+, 19.1.F emur:l ength,9 2.0, 93.3, 98.7; proximal
width and depth, 25.7 x 22.2, 25.4 x 21.9, 26.3 x 23.3; greatest diameter of
head, 12.2, 11.4, 12.5; shaft width and depth at midpoint, 10.2 x 8.8, 10.5 x
10.1, 10.2 x 10.3; distal width and depth, 27.5 x 19.6, 26.8 x --, 28.8 x 20.9.
Tibiotarsus: length, 160, 151.5, --; length from proximal articular surface, 154.0,
146.5, 153.2;w idth ofproximal articular surface,2 2.7, 22.6, 23.6; lengtho f fibular
crest, 24.3, 29.5, 24.0; width and depth of shaft at midpoint, 9.9 x 8.2, 9.1 x
8.1, 10.3 x 8.7; distal width and depth, 22.0 x 22.7, 21.2 x 21.9, 22.4 x 22.5.
Tarsometatarsus: length, 85.1, 84.6, 85.8; proximal width, 22.6, 22.0, 22.9; width
and depth of shaft at midpoint, 12.1 x 8.2, 10.2 x 6.8, 11.5 x 8.0; distal width,
24.9, 24.5, 23.7; depth of middle trochlea, 13.0, 13.5, 12.6.
Diagnosis: Generally smaller and less robust than T. chauliodous, especially in
the hindlimb and coracoids. The rostrum anterior to the nostril is proportionately
longer and straighter (less decurved), the nostril smaller, the internarial bar narrower
and the lateral nasal bar wider than in T. chauliodous.
Remarks: Although T. xanion is certainly distinct from T. chauliodous, the
degreeo f differentiationb etweent heset wo speciess eemsr ather slightg iven that
there has been no land connection between Oahu and Maui Nui.
Storrs L. Olson & Helen F. James,
Descriptions of thirty-two new species of birds from the Hawaiian Islands: Part I. Non-Passeriformes
Ornithological Monographs 45 (1991)
The American Ornithologists' Union, Washington D.C.
elibrary.unm.edu/sora/om/om045.pdfStorrs L. Olson & Helen F. James,
Descriptions of thirty-two new species of birds from the Hawaiian Islands: Part I. Non-Passeriformes
Ornithological Monographs 45 (1991)
The American Ornithologists' Union, Washington D.C.
elibrary.unm.edu/sora/om/om045.pdf
