Euphorbia rayturneri (Euphorbiaceae), a New Species from Southwestern New Mexico, United States

2013·3.1 MB·English

by  Victor W Steinmann

7
New
Euphorbia rayturneri (Euphorbiaceae), a Species from Southwestern
New
Mexico, United
States
Steinmann
Victor W.
61600
Institute de Ecologfa, A.C., Centro Regional del Bajfo, Apartado postal 386, Patzcuaro,
Michoacan, Mexico. [email protected]
Eugene
Jercinovic
New
6285 Algodon Road SW, Deming, Mexico
88030, U,S.A, [email protected]
& &
W. Euphorbia W.
Abstract. Euphorbia rayturneri V. Steinm. rayturneri V. Steinm. Jercinovic,
New
new TYPE:
Jercinovic (Euphorbiaceae), a species endemic sp. nov. U.S.A. Mexico: Grant Co.,
New
to southwestern Mexico, United States, is Pitchfork Ranch, 32°25.072'N, 108°21.169'W,
described and illustrated. This summer annual 1605 m, 23 Sep. 2008, E. Jercinovic 827
occurs in desert grassland and known from three (holotype, NMC; isotypes, IEB, KSC, MICH,
is
made and Luna MO, UNM).
collections in Grant, Hidalgo, Figures
2.
1,
1400-1700
counties elevations of m. Given
at its
and we
limited distribution small population size,
IUCN Red
Endangered, according
Critically to List
The new species belongs Euphorbia
criteria. to L.
Anisophyllum Roep. on the basis of possessing
sect.
Herb
annual, prostrate, mat-forming with various
and
interpetiolar stipules opposite leaves that are
primary stems extending radially from a slender
Stems 8 cm,
taproot. to terete, strigulose with white,
a pubescent, prostrate herb with serrulate leaves that
mm,
often have a red blotch in the center and an ovary recurved hairs 0. 1-0.2 pubescence distributed
with undivided
styles.
IUCN intemodes 0.6-2. 2 cm. Stipules interpetiolar, sepa-
Key
words Euphorbia, Euphorbiaceae,
:
mm,
0.6-0.9
Red New rate, filiform, pilose or strigulose; leaves
Mexico, United
List, States.
opposite; blades ovate to elliptic, often slightly
X
0.5-1. 0.2-0.5 cm, apex margin
falcate, 1 acute,
Despite the flora of the southwest United States
sharply serrulate, base asymmetrical, one side
having been relatively well studied, our basic
round upper
cordate, the other to attenuate, surface
knowledge of the plants in the region far from
is still
new
and
complete, species continue
1
and toward the center, lower surface strigulose, only the
tered described at a constant rate (Ertter, 2000).
mm.
New Mexico ranks fourth among the 48 continental midvein evident; petiole 0.5-0. 9 Cyathia
mm.
peduncles 0.5-1. 6 Involucre obconical,
United States in terms of plant diversity (Legler, solitary;
X
mm,
decade 10 new 0.9-1. 2 0.8-1. 2 outer surface strigulose, inner
2010). In the past at least species of
mm,
0.2-0.4
vascular plants have been described from the surface sparsely pilose, lobes subulate,
state,
and 350 new records have been reported (Kelly pilose; glands 4, circular to transversely oblong, 0.2
X
mm,
0.2—
comm., With 43 0.3 green, yellow, or light pink, convex;
Allred, pers. 2010). at least native
species, the genus Euphorbia L. (Euphorbiaceae) is appendages absent or if present reduced to a narrow
New margin
one of the most speciose genera in Mexico flanking the outer portion of the gland, less
X
mm,
(Allred, 2012). therefore not surprising that than 0.1 0.2-0.3 entire, white to pink.
It is
recent field exploration and the study of existing Staminate flowers 5 to 8. Gynophore glabrous,
mm;
collections have resulted in the discovery of a exserted from the involucre 1.4-1 .8 ovary 3-
0.3-
distinctive annual species of Euphorbia that does lobed, strigulose to canescent; styles undivided,
mm,
0.4 tapering to the stigmatic tips, pink to red,
X
new
This species described here, and information glabrous. Capsules oblate, 3-lobed, 1.7-2 2.2-2.
is
mm, mm.
provided about habitat, distribution, conserva- strigulose; columella 1.5-1.9 Seeds not
is its
tion status, and taxonomic affinities. carunculate, broadly ovoid, nearly triangular in cross
Novon 22: 482-485. Published on 18 October 2013. 10.3417/2011014
doi:
Volume Number 4 Steinmann & 483
Jercinovic
22,
—
Fertile habit. B. Flowering branch. -
..
X
section, 1.2-1. 4 1. 0-1.1 mm, tan to light gray when counties at elevations of 1400-1700 m. Given the
immature, becoming brown blackish brown, apex a close proximity of the Gray Ranch the Mexican
to to
km
border than 10 southernmost
low, blunt point, base truncate, dorsal keel promi- (less at its limit), E.
may
nent, with 2 well-defined transverse ridges that do not raytumeri also occur in the adjacent state of
Chihuahua. The Ranch,
type the Pitchfork
pass through the dorsal keel. locality, is
located about 17 miles north of Interstate 10 along
Distribution and habitat. Euphorbia raytumeri is Separ Road. The ranch property consists of roughly
New
known
only from southwestern Mexico, United 12,000 acres just west of the Continental Divide.
It
States, where occurs in Grant, Hidalgo, and Luna includes several miles of the Burro Cienaga, which
it
&
Figure 2. Euphorbia raytumeri V. W. Steinm. Jercinovic. Seeds. Taken from the isotype, E. Jercinovic 827 (MICH).