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BOTANICAL EXPLORATION IN VENEZUELA - I 199
May 7, 1945, Julian A. Steyermark 62650, "leaves deep olive green
above and dull green beneath".
This species is habitally very similar to the West Indian Maxillaria
croceorubens (Reichb. f.) L. O. Wms. (Ornithidium croceorubens
Reichb. .) but the petals and lip are very different.
Oncidium diffusum C. Schweinfurth, sp. nov.
Herba epiphytica, venusta. Rhizoma abbre via turn. Pseudobulbi
aggregati, ovoidei vel anguste ovoidei, valde complanati ut videtur,
apice unifoliati. Folium la nee ola to-elliptic urn, acutum, in petiolum
brevem sulcatum angustatum, membranaceum. Inflorescentia lateralis,
pendula, diffusa, perlaxe paniculata cum ramis laxe paucifloris.
Flores parvi, segmentis patentibus. Sepalum dorsale oblanceolatospathulatum,
infra longe angustatum. Sepala lateralia similia sed
majora, omnino libera, oblique spathulata, basi longe et anguste
unguiculata. P eta la obovato-spathulata, quam sepala breviora sed
latiora. Labellum suborbiculari-ovatum, basi cord a turn, supra conspicue
constrictum lobulum subquadratum retusum formans; discus
basi medio cum callo conspicuo apice tridentato ornatus. Columna
brevis, utrinque ala lata transverse oblonga praedita.
Plant epiphytic, graceful. Rhizome apparently abbreviated. Roots
fibrous, filiform, glabrous, numerous. Pseudobulbs crowded, ovoid
or narrowly ovoid, unifoliate at the apex, apparently strongly complanate,
about 3.7 cm. or less long, surrounded at base by one or
more pairs of distichous leaf-bearing sheaths which are evanescent
as the plant develops. Leaf petioled; lamina lanceolate-elliptic,
acute, cuneate below, membranaceous, about 13 cm. or less long and
2.6 cm. or less wide; petiole conduplicate, about 2 cm. or less long.
Inflorescence lateral, elongate, very loosely paniculate, diffuse,
pendent (detached in our specimen), apparently over 70 cm. long;
branches short, about 5-8 cm. apart, loosely few-flowered, with
slender fractiflex rachis. Bracts ovate, concave, acuminate with
prominent mid-nerve. Flowers small for the genus, with widely
spreading segments. Dorsal sepal oblanceolate-spatulate, subacute
at the recurved apex, long-narrowed to a very slender base, about
9.2 mm. long and 3*4 mm. wide above. Lateral sepals similar, entirely
free, obliquely spatula te, subacute with a recurved thickened
apex, gradually narrowed to a long sulcate claw, about 11 mm. long
and 3.9 mm. wide above. Petals obovate-spatulate, broadly rounded
at the apex (sometimes with a short acute tip),
narrowed to a short
claw, about 7.9 mm. long and 5 mm. wide above. Lip suborbicularovate
in outline, cordate at base, convex or reduplicate in natural
position rather abruptly constricted in front to form a relatively small
subquadrate terminal lobe which is bilobulate and apiculate, about
7.8 mm. long in greatest length (from either side of the base to the
apex) and 8 mm. wide below; disc provided through the basal central
half with a conspicuous callus which is irregularly toothed above and
terminates in three teeth of which the middle one is longest. Column