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68
University of California Publications in Botany
Almeda: Systematics
bur 148) (DUKE), Almeda 9 Wilbur 1484 (DUKE), Almeda 9 Wilbur 1485 (DUKE); ca. 3 mi beyond La
Georgina and 28.2 mi SE of El Empalme, Almeda 9 Wilbur 1511 (DUKE), Almeda 9 Wilbur 151)
(DUKE); ca. 7 mi beyond La Georgina and 32.3 mi SE of El Empalme, Almeda 9 Wilbur 1520 (DUKE),
Almeda 9 Wilbur 1521 (DUKE).
9. Monochaetum linearifolium Almeda, sp. nov.
(Fig. 19)
Frutex erectus ad 1.5 m altus; rami modice strigosi, trichomatibus barbellatis. Foliorum lamina linearis vel
oblonga (6-)ll-21(-26) mm longa et 1.5-4 mm lata, l(-3) nervata. Inflorescentiae terminales, pleramque
uniflorae vel dichasiales, bracteis (S-)5-8 mm longis et 0.5-1.5 mm latis. Calycis lobi lanceolati, 4-6 mm
longi et 2-3 mm lati, persistentes. Petala alba vel subrosea, 10-14 mm longa et 10-12 mm lata. Staminum
maiorurn filamenta 6-7 mm longa, thecis 8-10 mm longis, appendicibus dorsalibus 3-5 mm longis. Staminum minorum filamenta 7-10 mm longa, thecis 5-6 mm longis, appendicibus dorsalibus 3-4 mm longis. Stylus 7-9 mm longus. Hypanthium (maturum) cylindricum, 6-8 mm longum et 3-4 mm latum, strigosum, trichomatibus barbellatis. Semina 0.5 mm longa, brunnea, minute foveolata, cochleata.
Erect, compactly branched, arching shrub 1-1.5 m tall. Caultne internodes quadrangular, slightly
winged, or carinate with a sparse to moderate covering of appressed, barbellate trichomes. Older stems
woody, reddish-brown, the bark exfoliating. Principal leaves entire or remotely crenulate, covered with
evenly spaced trichomes marginally, dark green above, glabrous or with scattered, appressed, barbellate trichomes restricted to the apical margins or distal half to third of the blade; yellowish-green below, minutely
punctate with scattered trichomes prevailingly restricted to the median nerve, otherwise glabrous. Blades
linear-oblong, (6-)ll-21(-26) mm long, 1.5-4 mm wide, obtuse to rounded apically, acute to rounded basally, commonly with one elevated median nerve extending the entire length of the blade below, occasionally
some leaves bearing a pair of marginal, depressed nerves arising from the base of the blade and extending
for a third or less the length of the blade; petioles short, 0.5-1.5(-2.5) mm long, 0.2-0.5 mm wide. Flowers
borne singly, in pairs, o_r rarely in simple dichasia. Floral bracts gradually reduced in size upward, essentially like the principal leaves, (3-)5-8 mm long, 0.5-1.5 mm wide; subsessile or with petioles to 1 mm long.
Floral pedicels (5-)7-10 mm long, appressed-strigose. Hypanthia (at anthesis) campanulate with a sparse
scattering of appressed, barbellate trichomes, or glabrate, usually deeply pigmented as the distal branchlets. Hypanthia (at maturity) narrowly cylindric 6-8 mm long, 3-4 mm wide. Sepals (on mature hypanthia)
widely spreading, lance-triangular, ciliate, usually glabrous without, 4-6 mm long, 2-3 mm wide, persistent.
Petals white, drying to shades of pink or lavender, obovate, broadly rounded to emarginate apically, 10-14
mm long, 10-12 mm wide. Antepetalous staminalfilaments 6-7 mm long; anthers pinkish-red dorsally, suffused with yellow ventrally, 8-10 mm long, 0.8-1.0 mm wide; apical pore to 0.5 mm in diameter, appendages yellow, clavate, 3-5 mm long, 0.5 mm wide. Antesepalous staminal filaments 7-10 mm long; anthers
yellow, 5-6 mm long, 0.5 mm wide; appendages yellow, narrowly elliptic-lanceolate, 3-4 mm long, ca. 0.7
mm wide. Ovary (at maturity) oblong-cylindric. Style 7-9 mm long. Seeds 0.5 mm long, rusty brown,
minutely foveolate with a dull luster, cochleate.
Type.—COSTA RICA. Puntarenas Province, 3-3.3 km SE of Santa Elena on Cordillera de Tilaran, elev.
1500-1600 m, January 3, 1972, Almeda 9 Wilbur 1049 (Holotype, DUKE; isotypes, BM, BR, CR, F, G,
GH, K, LA, LL, MEXU, MICH, MO, NY, P, UC, US, W).
Flowering. — December through January.
Habitat and distribution. —Endemic to the Cordillera de Tilaran in the Province of Puntarenas, Costa
Rica, at elevations of 1500-1700 meters. The most common habitats are overgrown pastures with secondary
vegetation, disturbed sites, and steep, natural rockslides. Populations are locally common in clearings bordering forested areas where seedlings become established on decaying logs and old tree stumps (fig. 14).
Monochaetum linearifolium is unusual in having linear-oblong leaves with only the
median abaxial nerve prominently elevated. This character, together with quadrangular, carinate, or slightly winged distal branchlets and slender hypanthia sparsely beset
with barbellate trichomes, should preclude confusion with other species.
One collection, Almeda et al. 2009, has proliferating, adventitious roots along
nodes of the distal branchlets. The significance of these roots is unknown, but it seems
possible that dissociated branchlets with such structures could serve as effective vegetative propagules. Decumbent branches of M. floribundum and M. neglectum also
Fig. 19. Monochaetum linearifolium. A,
X 16; E, mature hypanthium and calyx lob
mature ovary and style, X 5. (A-H from /
ations in Botany
Almeda: Systematics of the Genus Monochaetum (Melastomataceae)
69
3 Wilbur 148) (DUKE); ca. S mi beyond La
•ur 1511 (DUKE), Almeda 9 Wilbur 1513
Empalme, Almeda & Wilbur 1520 (DUKE),
Almeda, sp. nov.
ibus barbellatis. Foliorum lamina linearis vel
•vata. Inflorescentiae terminates, plerumque
5 mm latis. Calycis lobi lanceolati, 4-6 mm
1-14 mm longa et 10-12 mm lata. Staminum
pendicibus dorsalibus 5-5 mm longis. Stami, appendicibus dorsalibus 3-4 mm longis. Stymm longum et 3-4 mm latum, strigosum, trilute foveolata, cochleata.
Cauline internodes quadrangular, slightly
ppressed, barbellate trichomes. Older stems
s entire or remotely crenulate, covered with
is or with scattered, appressed, barbellate triof the blade; yellowish-green below, minutely
he median nerve, otherwise glabrous. Blades
ie to rounded apically, acute to rounded basentire length of the blade below, occasionally
ng from the base of the blade and extending
.5(-2.5) mm long, 0.2-0.5 mm wide. Flowers
lets gradually reduced in size upward, essenvide; subsessile or with petioles to 1 mm long.
thia (at anthesis) campanulate with a sparse
iually deeply pigmented as the distal branch, 3-4 mm wide. Sepals (on mature hypanthia)
ithout, 4-6 mm long, 2-S mm wide, persistent,
iroadly rounded to emarginate apically, 10-14
•7 mm long; anthers pinkish-red dorsally, suf:; apical pore to 0.5 mm in diameter, appenous staminalfilaments 7-10 mm long; anthers
owly elliptic-lanceolate, 3-4 mm long, ca. 0.7
mm long. Seeds 0.5 mm long, rusty brown,
D
if Santa Elena on Cordillera de Tilaran, elev.
lotype, DUKE; isotypes, BM, BR, CR, F, G,
Tilaran in the Province of Puntarenas, Costa
abitats are overgrown pastures with secondary
julations are locally common in clearings bori decaying logs and old tree stumps (fig. 14).
ng linear-oblong leaves with only the
i character, together with quadranguand slender hypanthia sparsely beset
:usion with other species,
oliferating, adventitious roots along
f these roots is unknown, but it seems
ictures could serve as effective vegetaloribundum and M. neglectum also
B
Kg. 19. Monochaetum hnearifoUum. A, habit, X *; B-C. abaxial surface of typical leaves X 3- D se
X 16; E, mature hypanthium and calyx lobes, X 4; F, abaxial surface of floral b r a I t s X 5 G petal X 3 H
mature ovary and style, X 5. (A-H from Almeda 9 Wilbur 1049)
?
'
70
University of California Publications in Botany
produce adventitious roots when plants are grown under unusually moist, greenhouse
conditions.
Relationships. — Foliar morphology and crowded distal internodes give M. linearifolium an aspect reminiscent of M. uribei Wurdack, a Colombian species of restricted
distribution. In describing this species, Wurdack (1969) recognized two varieties based
on differences of foliar and cauline pubescence. The typical variety is glabrous except
for three stout, smooth trichomes at the apex of the hyaline margined leaves. The
variety arcabucense has sparsely strigillose cauline internodes and leaves that are glabrous above and sparsely beset with smooth, appressed trichomes below. Both varieties
share a distinctive, smooth, vernicose seed that is 1 mm long. Monochaetum linearifolium differs from both varieties in having distinctly barbellate trichomes, cylindric
hypanthia 3-3.5(-4) mm wide, shorter sepals (4.5-6 mm long), white petals, and
minutely foveolate seeds 0.5 mm long. The similarity between these two species may
reflect recent divergence from a common ancestral stock or morphological convergence. The distinct elevational ranges of these taxa and their restriction to disjunct
areas that have had dissimilar geologic histories lead me to favor the latter explanation.
Narrow leaved forms of M. calcaratum, Pringle 8359 (MEXU, NY, US), also superficially resemble M. linearifolium, but differ in having glabrous cauline internodes,
longer leaves (1.8-3.5 cm), oblong-urceolate hypanthia (8-10 x 4-5 mm) with smooth
trichomes, and much larger antepetalous anthers.
Despite these similarities, the relationship of M. linearifolium appears to be with M.
deppeanum, a variable species consisting of several isolated populations from Mexico
to Nicaragua. Both species have a barbellate trichome covering, cylindric hypanthia,
and single-flowered inflorescences, yet each has a different geographic distribution
and can be separated consistently by the diagnostic features outlined in the key to the
species.
Sympatry. —Monochaetum floribundum is the only species known to grow with M.
linearifolium. Both species occur near each other, but the population size of M. floribundum exceeds that of M. linearifolium. Natural populations of the latter in the Cordillera de Tilaran were observed at least twice yearly from 1971-73. As of my last visit
to the area, some colonies had been almost totally decimated owing to the local pattern of land use.
Monochaetum linearifolium apparently rarely hybridizes with M. floribundum.
One intermediate plant, Almeda & Wilbur 1050, found growing adjacent to its putative parents, has a combination of characters that casts little doubt on its hybrid origin
(table 9). No pollen or young floral buds were available, so it was not possible to determine its fertility or meiotic behavior. Provided the natural hybrids are as fertile as
those encountered in other interspecific combinations, the rarity of intermediates may
be due to factors which limit the extent of interspecific pollination. Monochaetum
linearifolium is never as abundant as M. floribundum; its inflorescences are few flowered and inconspicuous; its flowering period is rather brief.
Representative specimens. — COSTA RICA. Puntarenas: vicinity of Monteverde, Almeda 676 (DUKE); co.
3-S.5 km SE of Santa Elena and 2-S km E of Monteverde on Cordillera de Tilaran, Almeda, Flowers 9 Primack 2009 (CAS, DUKE, F, GH, K, MO, UC, US, W); Monteverde cloud forest, along trail over divide at
top of ridge, Luteyn 3684 (DUKE, US); ca. S.5 km NE of Monteverde on Penas Blancas trail, Wilbur,
Almeda 9 Luteyn 15794 (DUKE, F).
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quadrangular
strigose
linear-oblong, rounded apically
1.1-2.0(-2.5) cm
mostly 1 -nerved
glabrate or with few trichomes
apically
linear-oblong, 3-8 mm long
flowers single or paired on terminal
shoots
11-14 mm
8-9.5 mm
5-6 mm
oblong-cylindric
8-9 mm
narrowly cylindric, 6-7(-8) mm long
Cauline internodes
Internodal vestiture
Leaf shape
Leaf length
Abaxial foliar venation
Adaxial f o l i a r vestiture
Uppermost floral bracts
Inflorescence
Petal length
Large anther length
Small anther length
Ovary shape
Style length
Mature hypanthia
narrowly cylindric, 5-6 mm long
6-7 mm
narrowly obovoid
4-4.5 mm
6-7 mm
11-12 mm
once to twice compound on terminal
and lateral f loriferous shoots
elliptic to linear-elliptic, 3.5-6 mm
long
4 well-defined belts of appressed
trichomes between primary nerves
3-plinerved
1.6-2.51-3.2) cm
linear-lanceolate, acute apically
strigose
rounded quadrangular
Hybrid
(Almeda & Wilbur 10501
urceolate, 4-5.5 mm long
4.5 mm
ellipsoid to obovoid
2-3 mm
4-5 mm
10 mm
once to twice compound on terminal
and lateral floriferous shoots
cordate to ovate or subrotund, 1.5-3
mm long
4 well-defined belts of appressed
trichomes between primary nerves
3(-5)-plinerved
2.1-4.1 cm
elliptic-lanceolate, acute apically
retrorsely hirsute
terete
TABLE 9
A Comparison of Monochaetum linearifolium, M. floribundum, and Presumed Hybrid
M. linearifolium
(Almeda & Wilbur 1049)
ck, a Colombian species of restricted
(1969) recognized two varieties based
The typical variety is glabrous except
>f the hyaline margined leaves. The
; internodes and leaves that are glabessed trichomes below. Both varieties
s 1 mm long. Monochaetum lineaninctly barbellate trichomes, cylindric
4.5-6 mm long), white petals, and
larity between these two species may
stral stock or morphological conver:axa and their restriction to disjunct
lead me to favor the latter explana\e 8359 (MEXU, NY, US), also superhaving glabrous cauline internodes,
•anthia (8-10 x 4-5 mm) with smooth
rs.
I. linearifolium appears to be with M.
:ral isolated populations from Mexico
chome covering, cylindric hypanthia,
s a different geographic distribution
stic features outlined in the key to the
.e only species known to grow with M.
:r, but the population size of M. floriral populations of the latter in the Corearly from 1971-73. As of my last visit
illy decimated owing to the local pat-
M. floribundum
(Almeda & Wilbur 1048)
ely hybridizes with M. floribundum.
<0, found growing adjacent to its putaat casts little doubt on its hybrid origin
vailable, so it was not possible to deterd the natural hybrids are as fertile as
ations, the rarity of intermediates may
.terspecific pollination. Monochaetum
undum; its inflorescences are few flow> rather brief.
cinity of Monteverde, Almeda 676 (DUKE); ca.
a Cordillera de Tilaran, Almeda, Flowers 9 Prionteverde cloud forest, along trail over divide at
of Monteverde on Penas Blancas trail, Wilbur,
72
University of California Publications in Botany
Putative hybrid between Monochaetum linearifolium and M. floribundum. —COSTA RICA. Puntarenas:
ca. S-3.5 km SE of Santa Elena and 2 km E of Monteverde, Almeda & Wilbur 1050 (DUKE).
10. Monochaetum vulcanicum Cogn. in DC. Monogr. Phan. 7:401. 1891
Type, — COSTA RJCA. Alajuela Province; Volcan Poas, elev. 2600 m, Pittier 789 (Lectotype, BR1; isolectotypes, BRI [2 sheets], USI).
Monochaetum carazoi Cogn. in DC. Monogr. Phan. 7:401. 1891.
Type. —COSTA RICA. Alajuela Province: Volcan Poas, elev. 1900 m, Pittier 788 (Lectotype, BR1; isolectotypes, BRI, CR1).
Monochaetum vulcanicum f. costaricense Gleason, Amer. J. Bot. 16:591. 1929.
Type.— COSTA RICA. Heredia Province: Lago del Volcan Barba, Hoffman 5 (Lectotype, USI).
Monochaetum vulcanicum f. glandulosum Gleason, Amer. J. Bot. 16:591. 1929.
Type.— COSTARICA. San Jose Province: Volcan Irazu, near crater, elev. SSOOm, Pittier 14103 (Holotype,
NY!; isotypes, Gl [2 sheets], USI [2 sheets], Wl).
Monochaetum vulcanicum f. typicum Gleason, Amer. J. Bot. 16:591. 1929.
Erect, somewhat arching, bushy shrub to 1-3 m tall. Cauline internodes of the distal branchlets distinctly
quadrangular, somewhat carinate or slightly winged with one pair of flat, opposing faces usually narrower
than the remaining pair. Internodal trichomes appressed, distinctly barbellate, 0.5-2 mm long. Older stems
woody, reddish brown, the bark markedly exfoliating. Principal leaves entire, revolute on drying; dark
green above, essentially glabrous or with scattered trichomes restricted to narrow belts along the distal half
or third of the blade; yellowish-green below on drying, minutely punctate, densely appressed-strigose on the
elevated primary nerves and strigillose or less commonly glabrous between them; blades ovate, elliptic-ovate,
or obovate, 5-30 mm long, 2-14 mm wide, obtuse, rounded, or varying to acute apically and basally,
cuneate to attenuate basally when leaves are obovate in outline, 3-5-plinerved with pocules where the innermost pair of nerves diverges from the median nerve, if 5-plinerved, the outermost pair of nerves depressed
and often concealed by the foliar margins; petioles l-3(-7) mm long, 1-1.5 mm wide. Inflorescence terminal,
often congested with proliferating, lateral, floriferous shoots, commonly a once- to twice-compound dichasium. Floral bracts reduced in size and differing in shape upward; lowermost bracts like the principal leaves; '
uppermost bracts three-nerved, linear-oblong, oblanceolate, or spatulate, gently tapering basally into a
compressed, deeply pigmented, ill-defined petiolar region, (4-)7-12(-13) mm long from base to apex, l-3(-4)
mm wide. Floral pedicels (5-)6-10(-15) mm long. Hypanthia campanulate at anthesis, beset with flexuous,
appressed, barbellate trichomes and often intermixed with spreading, glandular trichomes. Hypanthia (al
maturity) narrowly to squatly campanulate (5-)6-9 mm long, 4-5 mm wide. Sepals (on mature hypanthia)
widely spreading, lance-triangular, ciliate, sparsely strigose without, (5-)6-9 mm long, 4-5 mm wide, persistent. Petals magenta, drying to shades of purple, obovate to obdeltoid, truncate, emarginate, or retuse apically, entire but often tipped with slender, glandular, or eglandular trichomes, 1.4-2.2 cm long, 1.2-1.5
(-1.7) cm wide. Antepetalous stamina!filaments 6-9 mm long; anthers red dorsally, often flushed with yel- '
low ventrally, 7-10 mm long, 1-1.5 mm wide; apical pore 0.5 mm or less in diameter; appendages yellow,
navicular to subterete in outline, 4-5 mm long, 0.5 mm wide. Antesepalous staminal filaments 7-11 mm
long; anthers yellow, 4-6 mm long, 1 mm wide; appendages yellow, linear-elliptic, (2-)3-4 mm long, 0.5 mm
wide. Ovary obovoid at maturity. Style (6-)7-10(-12) mm long. Seeds 0.5 mm long, light brown, minutely
foveolate, cochleate; n = 18.
Flowering.— November through March, and sporadically during other months of the year.
Habitat and distribution. —Endemic to Costa Rica; largely restricted to the volcanic slopes of the Cordil
lera Central at elev. 2200-3300 m with one known outlying population on SW slopes of Volcan Rincon de li
Vieja in northern Costa Rica. This species colonizes disturbed sites, roadsides, wet, open meadows, pasturelands, margins of volcanic craters, and lakes (fig. 7).
Monochaetum vulcanicum is well represented in herbaria, but over two thirds of the
specimens were collected at high elevations on Volcan Poas. This reflects the accessi-l
bility of that area since this species is locally common at comparable elevations on Volcan Barba and Volcan Turrialba. According to label data on Pittier 14103 (G, NY,|
US, W), M. vulcanicum was common in areas adjacent to the craters of Volcan Irazii,
The eruptions of 1963-65 appear to have greatly decimated populations of M. vulcam-
Almeda: Systematic:
cum, for my recent visits to i
plant.
Although Gleason's (19296
pared a synoptic treatment of
cies into three forms based i
Plants of his forma typicum 1
wide, and appressed hypanthi
of Volcan Poas and Volcan TV.
these two peaks are the most v*
from the typical form in havin
broad. According to Gleason tl
Volcan Irazu, designated as i
other slopes by their 5-plinerve
appressed, barbellate hypanth
My evaluation of variation ii
Poas have smaller leaves (5-16
from other slopes have larger 1<
obovate. Study of specimens ii
modally recognizable grouping
elliptic-ovate leaves that are 25 i
Gleason attributed only to Vo^
Almeda 589). Because of the la
tions, M. vulcanicum is treated
categories.
Relationships.—Gleason's (19
tre, and M. strigosum to the alp
the discussion of M. alpestre, thi
M. vulcanicum and M. strigosum
The affinities of M. vulcanicu't
the Cordillera de Talamanca in
pressed, barbellate cauline trich
Monochaetum vulcanicum is easi
America species with magenta fl
ovate, elliptic-ovate, or obovate
pubescent above.
Sympatry. — Two to four specie
canic slope of the Cordillera Centr
cum are unknown. This is best es
higher, wetter habitats. Monachal
species of the genus known from Vi
vations, effecting ecological separ;
Distributions of the four Monocf,
but M. vulcanicum is still isolated
preference. Despite this separation,
M. neglectum were found near the:
Barba (see discussion under M. ne,
The most intriguing pattern of sy