Burt-Utley, K. and J.F Utley. 2014. New species of Begonia (Begoniaceae) from Guerrero, Mexico. Phytoneuron 2014-6: 1-9.
Published 6 January 2014. ISSN 2153 733X

NEW SPECIES OF BEGONIA (BEGONIACEAE) FROM GUERRERO, MEXICO

KATHLEEN BURT-UTLEY and JOHN F. UTLEY
Institute for Systematic Botany
Department of Cell Biology, Microbiology, and Molecular Biology
University of South Florida
Tampa, Florida 33620-5150
kburtutl@uno.edu; jutley@uno.edu

ABSTRACT
Three new species of Begonia from Guerrero are described, discussed, and illustrated: B.
martinezii Burt-Utley & Utley, B. macvaughii Burt-Utley & Utley, and B. tlapensis Burt-Utley &
Utley.

Begonia in México is represented by 112 currently recognized species, including the three
that are described herein. Of these, 37 of the 56 known taxa with leafy erect stems develop from
underground tubers and are characteristic of many species in sect. Knesebeckia (K1.) A. DC., as
circumscribed by both Klotzsch (1854) and Alphonse de Candolle (1859, 1864). The Mexican
tuberous species, with few exceptions, occur in western and central México and Oaxaca in seasonally
dry environments, where their habitats range from areas with tropical deciduous forests to pine-oak or
oak forests and rarely cloud forests. In Flora Novo-Galiciana, 19 of the 25 Begonia species treated
are tuberous (Burt-Utley & McVaugh 2001) and represent just over half the tuberous species from
México (Burt-Utley, pers. obs.). Moreover, 17 of the recognized tuberous species are known to
develop bulbils in their leaf axils and, in some instances, leafy erect stems grow from the tubers but
produce only bulbils, allowing these species to reproduce asexually in the absence of flowering.
Once bulbils are dispersed, they can sprout and develop into new, presumably genetically identical
tuberous individuals. In Guerrero, there are 21 known tuberous species, including the species
described herein, 10 of which produce bulbils in their leaf axils. In contrast to the situation in
México, only five tuberous species are reported from all of Central America, and only two of these
taxa are endemic there. With the recognition of B. martinezii, B. tlapensis, and B. macvaughii, there
are now 28 known Begonia species reported from Guerrero.

1. BEGONIA MACVAUGHII Burt-Utley & Utley, sp. nov. Type. MEXICO. Guerrero. 12.3 mi
N of MEX 200 on MEX 134 from Salitrera to Cd. Altimirano, 1000 ft, 22 Jul 1990, /. Utley
& K. Utley 8531 (holotype: MEXU; isotypes: CAS, DUKE, MICH, MO, NY, UC, US, USF).
Figure 1.

Begonia biserrata Lindl. var. glandulosa L.B. Sm. & Schub., 1945. Contr. Gray Herb. 154: 23.
TYPE. MEXICO. Guerrero. Wet cliffs near Acapulco, 24 Jun 1935, O.M. Clark 7223
(holotype: NY; isotype: MO!).

Monoecious herbs 3.6—13 dm tall, developing annually from underground tubers 2.2-2.6 cm
diam. leafy stems erect, branching freely, occasionally producing solitary large bulbils to 5 mm at the
nodes; internodes of main stem elongate, 3-11 cm, sparingly to densely villous with white-clear
spreading trichomes 0.5-3 mm, these occasionally appearing glandular tipped. Leaf blades
decreasing in size from mid-stem to apex, asymmetric, transverse to oblique, rarely almost straight,
ovate to narrowly ovate or broadly obovate in outline, 6.5-24 X 2.8-12 cm, basally cordate to very
shallowly cordate, apically acute to rounded or acuminate to attenuate-acuminate, marginally usually
deeply (2-)3(—5)-lobed, rarely unlobed, the lobe opposite the petiole insertion to 2 the width of the
blade or more, lobes acute to rounded or acuminate, ciliate and ciliate-denticulate to ciliate-serrulate,

Burt-Utley and Utley: New Begonia species from Guerrero, Mexico 2

villous above and beneath, 4-6(-9)-palmatinerved; uppermost blades greatly reduced to wanting,
when present frequently very narrowly ovate; petioles decreasing in length from plant base to apex,
2-12 cm, villous with spreading trichomes 1-3 mm; stipules persistent, ascending to spreading,
symmetric to asymmetric, the pairs unequal, oblong-ovate to broadly oblong, 2-8 X 1.5-7 mm,
marginally ciliate-incised, sparingly villous. Inflorescences axillary and terminal, occasionally with
a large bulbil at the nodes, few-many-flowered; peduncles 1.3-3.5(-4.5) cm, villous with usually
glandular tipped trichomes to 2 mm; bracts persistent to very tardily deciduous, spreading, ovate to
oblong or obovate, 2-3.5 X 1.5-2.5 mm, marginally and apically ciliate-laciniate, glabrous to very
sparingly villous. Staminate flowers with pedicels 0.8—1.7 cm, glandular-villous; sepals 2, ovate or
narrowly ovate, (0.9-)1.1-2.1 X 0.6-1.4 cm, apically acute to attenuate-acuminate, marginally
sparingly irregularly ciliate to ciliate-denticulate, villous, light to dark pink, petals 2, elliptic to
obovate or ovate, (0.7-)1-1.9 cm X (3-)5.5-8 mm, apically rounded to attenuate-acuminate,
marginally very sparingly ciliate, glabrous, colored like the sepals; stamens 46-74, monadelphous;
filaments 1-1.5 mm; anthers obovoid to ellipsoid, 0.6-1 X 0.6-1 mm. Pistillate flowers with
pedicels (13—-)18-25 mm, glandular-villous; bracteoles wanting; tepals 5 or if 4, then 1 deeply
bilobed, subequal, ovate to broadly ovate or obovate, (0.9-)1.2-1.8 cm X (3—)5-12 mm, margins
somewhat undulate and occasionally irregularly to regularly ciliate, the outer 3 only villous, light to
dark pink; ovaries trilocular with bipartite placentae, (4.5—)8-12 mm, villous to minutely glandular
and villous; styles 3, 1-2.5 mm fused to half their length; stigmas bicornute. Capsules with pedicels
2.1-4 cm; bodies 1.4-1.9 cm; locule chambers externally appearing obovate to elliptic, (0.8—)1-1.2
cm X 6.5-9.5 mm; wings 3, the primary wing asymmetrically triangular to ovate, (1.3-)1.6-2.1 X
1.2-1.7 cm, marginally sparingly ciliate to ciliate-denticulate distally; the second asymmetrically
lunate to symmetrically triangular, 5—13 X 9-14 mm; the third marginiform, and lunate-triangular.

Additional specimens examined. MEXICO. Guerrero. Mpio. Juan R. Escudero, Los
Copalitos cerca El Zapote, 1 Jul 1986, M.A. Gomez & L. Marquez (MEXU); Mpio. Mochitlin, Agua
de Obispo, 850 m, 12 Jul 1980, L. Garcia Marinez 86 (MEXU); 890 m, 12 Jul 1981, J. Pérez
Martinez 98 (MEXU); R. Gonzalez 62 (MEXU); 850 m, 27 Sep 1987, G Espinosa Flores 220
(MEXU); Dist. Montes de Oca, Mpio. Montes de Oca, Vallecitos, 11 Jul 1937, Hinton 10593 (K, LL,
UC, US); Mpio. Tierra Colorada, 12 km despues Tierra Colorada, carr. Tierra Colorada-Teconapa, 28
Jun 1985, G Espinosa Flores 398 (MEXU); steep limestone banks on Hwy 95 ca 11.4 mi N of Tierra
Colorada or 4.5 mi N of Ocotito (km 50), 2800 ft, 17 Jul 1989, Utley & Utley 8397 (CAS, CGE, GH,
IBUG, LL, MEXU, MICH, MO, NY, US, USF); Mpio. Zihuatanejo, 21 km NE de la desviacion a Cd.
Altamirano, sobre la carr. Zihuatanejo-Cd. Altamirano, 400 m, 24 Jul 1996, J. Soto Nufiez, Roman de
Soto & Soto Roman 9654 (MEXU, USF); Mpio. Aint en la Mesita 21 km NE de la desviacion
a Cd. Altamirano sobre la carr. Zihuat Cd. Al 400 m, 24 Jul 1996, J. Soto Nufiez, A.
Roman de Soto & F. Soto Roman 9654 (MEXU); 12 mi S of Tierra Colorada, 1200 ft, 20 Jun 1952,
E.H. Cooper & C.M. Rowell 2646 (MICH); 6 mi N of Ocotito, 3000 ft, H.A. Floyed & C.L. Ryan 317
(MICH); 0.5 mi N of Acahuizotla, 2800 ft, 26 Jun 1954 m D.F Herald & ELE. Clark 335 (MICH,
TEX); 2 mi 8S of Acahuizotla, 3000 ft, 16 Jul 1952, C. Rowell 3090 (MICH); Km 338, 3km beyond
Acahuizotla on hwy to Acapulco, 3000 ft, 23 Aug, 1948, H. Moore & Wood 4722 (BH, MEXU, UC).
Oaxaca. 20 km N of Pinotepa Nacional, 170 m, H.M. Hernandez & R. Torres 438 (MEXU).

Etymology. It is a pleasure to name this interesting species in honor of the late Dr. Rogers
McVaugh (1909-2009) who collected extensively in western México and undertook Flora Novo-
Galiciana. His publications on the travels of 19" century collectors in México have been an
invaluable resource for our research with Begonia and Hechtia (Bromeliaceae).

Distribution and habitat. Begonia macvaughii is known only from Guerrero and adjacent
Oaxaca between 170 m and 910 m, where it grows along moist roadbanks and stream banks in

Burt-Utley and Utley: New Begonia species from Guerrero, Mexico 3

UNIVERSITY OF

PLANTS OF MEXICO

Begonia

Guerrero: Mex 134, 12.3 miles N of Mex 200 along Hiwy
Altimiran:

stream, Elevation 1000 feet

Herb to 1.3 m on moist roadbanks; flowers dark pink
without, lighter within, apparently tuberous.

John and Kathy Utley # 8531

22 July 1990

Figure 1. Begonia macvaughii. Isotype (Utley & Utley 8531, USF).

Burt-Utley and Utley: New Begonia species from Guerrero, Mexico 4

evergreen forests, and bosques tropicales subcaducifolias, as well as on open, steep, limestone
roadbanks. It is expected to occur in Michoacan in the appropriate habitats.

Begonia macvaughii is an attractive species with oblique to transverse, basally cordate leaf
blades. It was originally described as B. biserrata var. glandulosa, but in examining extant specimens
and our collections of this latter taxon (Utley & Utley 8397 and Utley & Utley 8531), it became
obvious that these specimens represent a distinct species that is readily distinguished from B.
biserrata by both vegetative and floral characters. Unlike B. biserrata with its leaf bases that
superficially appear cordate but are cuneate at the petiole-blade junction and bordered on either side
by bladeless nerves, those of B. hii are lly cordate to very shallowly cordate with
the lowermost nerves bordered on either side by blade tissue. Moreover, leaf blades of B. macvaughii
have distinct leaf apices, in contrast to those of B. biserrata, which typically lack them. Interestingly,
leaf apices and lobe apices of B. macvaughii can vary in form within leaf blades of a single specimen.
The persistent stipules of B. hii also distinguish this species from B. biserrata with its
caducous to fugacious stipules. It also appears that B. hii is istentl ious while
B. biserrata is very frequently dioecious or sometimes temporally dioecious and rarely monoecious.
Inflorescence characters also readily distinguish this species from B. biserrata, the most obvious of
which is its persistent to tardily deciduous bracts that contrast immediately with the fugacious to
caducous bracts characteristic of B. biserrata.

2. BEGONIA TLAPENSIS Burt-Utley & Utley, sp. nov. TYPE. MEXICO. Guerrero.
Huamuxtitlan, 1.6 mi S of Huamuxtitlan on Mex 92 or 47.6 mi S of Hwy 190 on rd to Tlapa
de Comonfort, ca 3460 ft, 14 Jul 1991, /. Utley & K. Utley 8639 (holotype: MEXU; isotypes:
B, BH, BM, C, CAS, DUKE, F, GH, IBUG, K, M, MICH, MO, NY, UC, US, USF). Figure 2.

Monoecious herbs 8.5—39 cm tall, developing annually from underground tubers to 8 mm
diam; leafy stems erect, branching freely; bulbils not evident at nodes; internodes of main stem
elongate, (1.8—-)3-8.5 cm, lanate to pilose with very fine sericeous trichomes to 6 mm. Leaf blades
straight, symmetric, broadly transversely oblong-elliptic to deltoid or hemiorbicular, (2—)4—8(-11.5)
em X (2-)6—15 cm, basally cordate, apically shallowly acute or with no distinct apex, marginally
shallowly to very shallowly lobed, the lobes acute to acuminate or rounded, and ciliate-doubly dentate
to ciliate-doubly serrate, or ciliate-denticulate to ciliate-serrulate, typically densely pubescent to
lanate above, lanate below with trichomes matting, or only rarely pilose, 9-11-palmatinerved; petioles
typically wanting, rarely to 4 mm; stipules persistent, variable in form, asymmetrically ovate to
elliptic, dolabriform or triangular, (5.5—)7—13(—22) X (4—)6.5-13 mm, marginally ciliate to ciliate-
denticulate or serrulate, irregularly weakly lobed, pilose above and below, but occasionally glabrous
above. Inflorescences typically weakly asymmetrically cymose, axillary and terminal, 1-3 times
dichotomous, the uppermost inflorescences exceeding the foliage, several-flowered; peduncles (3—)4—
9.5 cm, pilose with trichomes 2—4.5 mm; bracts persistent, spreading to ascending, variable in form,
orbicular to hemiorbicular, broadly asymmetrically ovate or obovate, the lowermost 4.5-16 X 4-13
mm, marginally ciliate-laciniate to ciliate-serrulate, pilose to lanate. Staminate flowers with pedicels
1.1-2.4 cm, glabrous or occasionally sparingly pilose, sepals 2, suborbicular to very broadly ovate or
broadly elliptic, 8-13.5 X 8-14 mm, apically acuminate, marginally finely ciliate-denticulate, only
rarely sparingly so, externally glabrous to sparingly pilose, white to pale pink; petals 2, obovate, 10—
15 X 5.5-10 mm, marginally entire, white to pale pink; stamens 30-61, monadelphous; filaments 0.2—
2 mm; anthers broadly obovoid, 0.5-0.8 X 0.5-0.8 mm. Pistillate flowers with pedicels (0.9—)1.3—
2.5(-3.2) cm, glabrous to sparingly pilose, bracteoles wanting; tepals 5, occasionally persisting on
maturing capsules, variable in shape and size, unequal, suborbicular to obovate or broadly obovate,
7.5-10(-14.5) X 4-8(-12) mm, marginally finely ciliate-denticulate, only rarely sparingly so,
glabrous to sparingly pilose, white to very pale pink; ovaries trilocular with bipartite placentae,
ovuliferous throughout, 7.5—10(—13) mm, glabrous to sparingly pilose; styles 3, 1.5—2 mm, fused to

Burt-Utley and Utley: New Begonia species from Guerrero, Mexico 45

UNIVERSITY OF

SOUTH FLORIDA

HERBARIUM
2614

419

PLANTS OF MEXICO

Begonia

Guerrero: 1 6 miles south of Huamustitian along Mex 92

Comontort. Steep dry hillsides. Elevation about 3460 feet

steep rocky slopes. Tuberous; stems erect, green to
ee ly lanate, benching at odes: stipules green,
persistent, leaves green above, occasionally wih red
yea ileal, fe to may Reweron! Badunles
Green to red flowers whi to hgh suffused pink; ovaries
and immature capsules light green Rare, but in large
colonies

John and Kathy Utley # 8639

14 July 1991

Figure 2. Begonia tlapensis. Isotype (Utley & Utley 8639, USF).

Burt-Utley and Utley: New Begonia species from Guerrero, Mexico 6

half their length; stigmas bicornute, persisting on developing capsules. Capsules with pedicels (1.3-
)1.9-2.8 cm; bodies 8.5—14(-17) mm; locule chambers externally broadly obovate to transversely
elliptic, 6.5—9 X 6-9.5 mm; wings 3, unequal, the largest sometimes weakly arcuate, asymmetrically
triangular to ovate-elliptic, 9-16 X 7.5-11 mm; the second and third asymmetrically triangular to
ovate and subequal to each other, or occasionally the third shallowly lunate-triangular, 5-10 X 7-10
mm.

Additional specimens examined. MEXICO. Guerrero. Tlapa, 1300 m, 15 Aug 1972, E.
Matuda 38472 (CAS-[2], MO). Oaxaca. Distr. Juxtlahuaca, Laguna Esmeralda de Tecomaxtlahuaca,
12 km SW de San Miguel Tlacotepec, 2690 m, 18 Jun 1982, R. Cedillo Trigos & R. Torres 1452
(MEXU, USF).

Etymology. Begonia tlapensis is named after Tlapa de Comonfort, Guerrero, where Dr. Eizi
Matuda first collected this attractive species.

Distribution and habitat. Begonia tlapensis is known only from very dry calcareous areas
of Guerrero with thorn-scrub vegetation and seasonally dry forests of northern Oaxaca at elevations
between 1300 m and 2690 m. The type series is from a very dry region with thorn-scrub vegetation
and abundant Hechtia and Opuntia.

Begonia tlapensis is an attractive species that was abundant at the type locality. Within both
the type series and Matuda 38472, variation can be observed in pubescence density. Although
individuals of this species have predominantly lanate internodes, there are individuals within a
population with significantly less dense pubescence, as observed on Matuda 38472 (MO) that
consists of both a lanate specimen and a pilose one. Begonia tlapensis can immediately be
distinguished from other Mexican Begonia by its leaves that consistently lack petioles. Only two
other Mexican taxa are known to at least occasionally have apetiolate leaves, B. monophylla A. DC.,
with which B. tlapensis appears most closely allied, and B. angustiloba A. DC. — both are also from
Guerrero and other parts of western México (Burt-Utley & McVaugh 2001).

From Begonia monophylla, B. tlapensis is distinguished by its well-developed branching
stems with several leaves, in contrast to a single large basal leaf and modified stems with much
reduced to rudimentary leaf blades. In particularly robust specimens of B. monophyila, there may be
several slender branches originating from the stem at the lowermost node, each of which will then
produce multiple inflorescences (Burt-Utley & McVaugh 2001). Begonia tlapensis also differs from
B. monophylia in its larger stipules [(5.5—-)7—-13 X (4-)6.5—12.5 mm vs. 5.5—-8 X 1.5—4 mm], longer
peduncles (3.4—8.3 cm vs. 1.3—-5.5 cm), larger staminate sepals (8-13.5 X 8-14 mm vs. 3.5-8 X 2.5—
8.5 mm), and larger staminate petals (10-15 X 5.5—10 mm vs. 4-10 X 3-6 mm). Begonia tlapensis is
readily separated from the usually apetiolate, narrowly lobed leaves of B. angustiloba by the lack of
bulbils at its nodes, its pilose to lanate pubescence (vs. glabrous), leaf blades with 9-11 primary
nerves (vs. 3—4), well-formed upper leaf blades (vs. highly reduced to rudimentary, ovate to linear),
and several-flowered inflorescences (vs. 2-3-flowered).

3. BEGONIA MARTINEZII Burt-Utley & Utley, sp. nov. TYPE. MEXICO. Guerrero. MEX 134,
16.8 mi N of Vallecitos de Zaragoza on hwy from La Salitrera to Cd. Altamirano, 6000 ft, 22
Jul 1990, J. Utley & K. Utley 8538 (holotype: MEXU; isotypes: US, USF). Figure 3.

Monoecious herbs with leafy erect stems to 1 m tall, developing annually from underground
tubers 9-11 mm diam, stems branching, often with clusters of small bulbils to 1 mm diam at nodes of
stems and inflorescences; internodes of primary stems 5.5—10 cm, glabrous to very sparingly pilose
with trichomes to 1 mm; those stems developing from leaf axils very slender. Leaf blades oblique,

Burt-Utley and Utley: New Begonia species from Guerrero, Mexico 17

rarely straight or transverse, ovate in outline, 6.5-13 X 4-7 cm, basally very shallowly to deeply
cordate, apically acuminate to attenuate-acuminate, marginally somewhat variable, shallowly 1 or
more lobed at ends of major nerves, doubly serrate-crenate, or doubly dentate or serrate and
denticulate to serrulate and irregularly ciliate, above appearing glabrous but minutely glandular to
very short villous throughout, below glabrous to short villous and minutely glandular, upper blades
similar to lower blades but greatly reduced in size; 7—-10-palmatinerved, petioles (1.5—)4—9(-12) cm,
with a ring of broad villi 1.5-3 mm on the petiole just below the petiole-blade junction, otherwise
glabrous to very sparingly villous with trichomes to 0.8 mm; stipules persistent, spreading to reflexed,
often asymmetric, broadly to very broadly ovate or deltoid, 2.5-8 X 3.5-8 mm, apically obtuse to
truncate, marginally ciliate-denticulate to irregularly ciliate, often minutely glandular and very
sparingly villous within, glabrous without. Inflorescences axillary and terminal, often producing
small clusters of bulbils at bases of branches, symmetrically cymose, appearing 4 or more flowered,
usually with 2 male and 2 female flowers; peduncles 5—7.5 cm, glabrous to very sparingly villous;
bracts deciduous to persistent, asymmetric, the lowermost broadly ovate to obovate or hemiorbicular,
(6—)10-14 X (6-)9-17 mm, unlobed to 2-3 lobed or the 2 bracts fused, marginally irregular ciliate
with stalked glandular hairs, denticulate to serrulate, incised or undulate, within sparingly minutely
glandular, without minutely glandular and glandular-villous. Staminate flowers with pedicels 8-14
mm, glabrous to sparingly glandular or glandular and glandular-villous with trichomes to 1.2 mm;
sepals 2, ovate, 18-23 X 14-16 mm, apically acute to acuminate, marginally crenulate to serrulate
and glandular with short, stalked hairs, externally irregularly glandular and glandular-villous; petals 2,
elliptic to obovate, 14.5-20 X 7-11.5 mm, marginally distally shallowly serrulate-crenulate or
undulate, appearing glabrous but minutely glandular; stamens +/- 45-53, monadelphous; filaments
0.5-1.5 mm; anthers obovate to elliptic, 0.9-1 X 0.7-0.8 mm. Pistillate flowers with pedicels 5-9
mm, glabrous to conspicuously glandular-villous; bracteoles wanting; tepals 5, variable in shape and
size, elliptic to ovate or obovate, 10-18 X 4-9 mm, marginally weakly glandular-crenulate to
serrulate, externally glabrous to glandular or glandular and glandular-villous with stalked glandular
hairs; ovary apparently trilocular with bipartite placentae, 7 mm, minutely glandular or glandular and
glandular-villous with stalked glandular trichomes; styles to 0.7 mm, fused briefly basally; stigmas
bicornute. Capsules not seen, but ovary wings 3, 2 subequal to each other, triangular and the third
appearing marginiform, shallowly triangular to rounded or truncate apically.

Additional specimens examined. MEXICO. Guerrero. Mpio. Atoyac de Alvarez en las
Golondrinas, a 22 km NE de Fila de Caballo, 1600 m, 7 Sept 1983, E. Martinez S. and J.L. Villalobos
4239 (MEXU, USF); 15.8 mi by rd N of El Paraiso on rd from Atoyac de Alvarez to Milpillas, 5440
ft., 4 Jul 1982, Thomas, Rawlins, & Sholes 2883 (NY).

Etymology. Begonia martinezii is named after Esteban Martinez at MEXU, who collected
this species in 1983.

Distribution and habitat. Begonia martinezii is known only from Guerrero, where it has
been collected between 1600 m and 1830 m in evergreen forests or on steep, wet, rocky roadbanks of
cloud forests. It is likely to occur in adjacent Michoacan in the appropriate environments.

Begonia martinezii is an attractive tuberous species with large staminate and pistillate flowers
that rarely has been collected. This species is variable in its indument, as evidenced by the
pubescence observed on the type series, Utley & Utley 8538, but in other characters the pubescent
specimens are identical to those with very sparse pubescence like Martinez S. & Villalobos 4239
(USF). The presence of clusters of bulbils to 1 mm like the ones observed on B. martinezii can be
observed on seven other tuberous Begonia from western México that are known to produce clusters of
small bulbils to 1 mm in their leaf axils.

Burt-Utley and Utley: New Begonia species from Guerrero, Mexico

910-60 ON 189

PLANTS OF MEXICO coe

UNIVERSITY OF

SOUTH FLORIDA

ioe
2614

Guerrero: MEX 134, 16 8 mies Nf Vaecios do

Toadbanks in zone de neblina Elevation 6000 feet,

Herb, bulbiterous, sometimes producing bulbils

John and Kathy Utley # 8538
22 July 1980

UNIVERSITY

Figure 3. Begonia martinezii. Isotype (Utley & Utley 8538, USF).

8

Burt-Utley and Utley: New Begonia species from Guerrero, Mexico 9

In certain vegetative characters, Begonia martinezii is similar to both the Mexican endemic,
B. boissieri A. DC. from the states of Guerrero and México and the Guatemalan endemic B.
gracilioides Burt-Utley & Utley, but it is readily distinguished from these species by both vegetative
and floral characters. Bulbils have been observed on stems of B. martinezii and B. gracilioides but
are wanting on specimens of B. boissieri examined. Stipules of B. martinezii, are persistent and
broadly to very broadly ovate or deltoid and similar to those of B. gracilioides but differ from the
very narrowly triangular to very narrowly oblong or obovate and fugacious stipules in B. boissieri.
There are differences in the numbers of major nerves among these three taxa. Leaf blades of B.
martinezii are 7-10-palmatinerved, while those of B. gracilioides are 6-8-palmatinerved and those of
B. boissieri are 10—-11(—14)-palmatinerved. A major difference among these species is the form of the
uppermost leaf blades. In both B. martinezii and B. boissieri, the uppermost leaves are somewhat
reduced, but have the same shape and conspicuous petioles like their lower leaves. In B. gracilioides
the uppermost leaves are greatly reduced and almost linear with very short petioles to 3 mm.
Uppermost leaves like those observed on B. gracilioides also are observed on a number of Mexican
taxa including B. angustiloba A. DC. and B. balmisiana Balmis. It is also significant to note that
these leaves are occasionally fused with stipules at the nodes (pers. obs.).

Inflorescences of Begonia martinezii and B. gracilioides are few-flowered and symmetrically
cymose, but those of B. boissieri are often many-flowered and weakly to strongly asymmetrically
cymose. In both B. martinezii and B. boissieri, the stems are terminated by elongate peduncles
bearing 4 or more flowers, but those of B. gracilioides have shorter peduncles and 1-2 flowers.
Pistillate flowers also distinguish these three species, with those of both B. martinezii and B.
gracilioides having ebracteolate ovaries, while those of B. boissieri have bracteolate ovaries with
large bracteoles exceeding the ovaries in length at anthesis and bracteole scars that can be observed at
the base of the capsules. There also appears to be a difference in capsule wings, with those of B.
martinezii having two large, narrow asymmetrically triangular wings subequal to each other and a
marginiform wing, in contrast to those of both B. boissieri and B. gracilioides with unequal wings,
with the largest broadly but shallowly asymmetrically ovate or triangular and the other two very
shallowly lunate to triangular.

ACKNOWLEDGEMENTS
Field work was made possible in part by grants from the Standley Smith Horticultural Trust
and the American Philosophical Society. Mr. Alan Franck we thank for digital images of the type
specimens, and we especially thank the curators of the following herbaria for the loan of specimens or
use of facilities that made this research possible: K, LL, MEXU, MICH, MO, NY, TEX, UC, US, and
USF.

LITERATURE CITED
Burt-Utley, K. and R. McVaugh. 2001. Begoniaceae. In R. McVaugh & W.R. Anderson (eds.).
Flora Novo-Galiciana 3: 653-695.
Candolle, A. de. 1859. Memoire sur la famille des Bégoniacées. Ann. Sci Nat. IV. 11: 93-149.
Candolle, A. de. 1864. Begoniaceae. Prodr. Syst. 15(1): 266-408.
Klotzsch, J.F. 1854. Without title. Monatsber. Kénigl. Preuss. Akad. Wiss. Berlin 1854: 119-128.