New Combinations in the Pleopeltis macrocarpa Group (Polypodiaceae: Polypodieae)

8 Pages·1995·4.5 MB·English

by  Elisabeth Andrews Hooper

American
Fern Journal 85(3):75-82 (1995)
New
macrocarpa
Combinations
in the Pleopeltis
group
(Polypodiaceae: Polypodieae)
Andrews
Elisabeth Hooper^
KS
Department of Botany, University of Kansas, Lawrence, 66045
m
Sim
and epiphytic, and the species occur most frequently between 1500 and 2500
m
common
They
wet
in disturbed habitats of forested areas. are especially
and on such and
along roadsides, edges of pastures, cultivated trees as coffee
citrus. In addition to their simple leaves, members of the P. macrocarpo group
are characterized by anastomosing venation; large sori subtended by a nexus
of veinlets; rhizome, and soral scales that are peltately attached and at
leaf,
chromosome number x=34 The
least partially clathrate; and a base of or 35.
com
form
a
mam
ment
most
innatifid leaves, of the
sf
simole leaves and belong to the
m
isozymic
circumscription
on paraphyses
two because of the reliance peltate as
arisen reasons.
for First,
R
munchii and
the main diagnostic feature for the genus, several species (e.g.,
R
have been included in Pleopeltis, despite the fact that they share
fallax)
R
and members of the macrocarpa group other
para
members Polypodium Margin
macrocarpa group and scaly-leafed of (subg.
Anthony and Mickel and
(Wagner and Wagner, 1975; Schelpe, 1985; Beit
ia)
boundary
two
these groups.
DNA
(Andrews
isozyme and chloroplast surveys
Furthermore, preliminary
and Haulier and Ranker, in press] revealed greater genetic affin-
Haufler, 1990;
R
members macrocarpa
and
between two Polypodium species of the
ity scaly
group than between the former and non-scaly polypodiums. This genetic ev-
and
indu-
rhizome, soral
idence, coupled with the strong similarities in leaf,
Windham
mentum and Hennipman, led
between two (Baayen 1987),
the
Whereas
Polypodium species into Pleopeltis. this
four scaly
(1993) to transfer
new evolutionary relationships
arrangement more accurately portrays the
MO
Northeast Missouri State University, Kirksville,
Present address: Division of Science,
^
63501.
AMERICAN FERN VOLUME NUMBER
76 JOURNAL:
85
3 (1995)
among
these taxa, Pleopeltis remains a heterogeneous assemblage
of species
that difficuh circumscribe.
to
is
Despite these perturbations the generic the simple-leafed members
at level,
of Pleopeltis remain a relatively cohesive and apparently monophyletic group
that has received little systematic attention in the past (but see Weatherby,
A
R
1922). revision of the macrocarpa group was
initiated to explore taxo-
nomic and among
evolutionary members and
relationships
its to serve as a
springboard for additional studies within Pleopeltis and the Polypodieae. The
results of these studies will appear elsewhere; the purpose communi-
of this
cation to present the necessary nomenclatural changes
is that arose as a result
of these studies.
um
complanata comb
peltis (Weath.) E.A. Hooper,
G
latum complanatum
L. var. Weath., Contr.
macrocarpa
(Bory ex complanata
Willd.) Kaulf. var. (Weath.) Lel-
Wash. 1977.—
Proc. Biol. Soc. 89:722. Type: Costa
Rica, Pcia. Car-
J
m
Tiplanata occurs from 1200 2300 montane
to in
m
Panama.
has been maintained
It as a variety of
P.
{^Polypodium
lanceolatum
Weath
L.) since original descrlntion bv
its
m
it is sufficiently distinct from P. macrocarpa to be recognized as a separate
species. For example, P. complanata differs from macrocarpa in having a
P.
flattened stipe (versus terete); narrowly lanceolate leaves (versus narrowly
el-
liptic); slightly sinuate leaf margins (versus entire but slightly revolute); small-
mm
and
er leaf soral scales (ca. 1 smaller in diameter on average); and two-
celled spores (versus These
single-celled). differences are best expressed in
material
two com
differ in that
P.
macrocarpa known
is to contain only tetraploid, pentaploid, and hexaploid
cytotypes (Manton,
1959; Jarrett et 1968; Walker, 1966, 1973; Wagner and
al.,
Wagner,
1975; Hooper, 1994). Furthermore, isozyme comparisons of the two
(Hooper,
1994) revealed that relative to most species pairs in the macrocarpa
P.
group, complanata
P. has a relatively low genetic identity with macrocarpa
P.
=
(Nei's
0.653).
1
The two
species occasionally grow together in southern Central America and
careful observation required them
is to distinguish in the For example,
field.
the flattened stipe of complanata not obvious on on
P. is as live plants as
is
it
dried specimens.
Nevertheless, combination and
the of morphological genetic
divergence between two
the support
their recognition as separate species.
Pleopeltis polylepis (Roem. ex Kunze) Moore, Index 1862.—
T. 348. -Poly-
Fil.
podium
Roem.
polylepis ex Kunze, Linnaea 1839.—
13:131. Syntypes:
Mexico, Mineral del Monte, Ehrenberg without Hegewisch
s.n.; locality,
(Herb. Roemer); Karwinsky
s.n. (probably
s.n. all LZ, destroyed; teste
Mickel and
Beitel, 1988).
Polypodium
peltatum PL
Cav., Descr. 244 (No. 1802.—Lectotype:
597).
"Marianas Nee
Islands", two
s.n.; there are sheets in the type collection,
NEW
HOOPER: COMBINATIONS
PLEOPELTIS
IN
77
and
for reasons discussed below, the specimen above lower
the right-hand
476120
label of sheet no. in the Herb. Cavanilles lA) has been chosen
(Fig.
[MA,
as lectotype photo be deposited
(to at UC)!].
Mem.
Drynaria Fam.
vestita Fee, Foug. 5 (Gen. Fil.):271, 1852.—Type:
Mexico, Galeotti not found by Mickel and
s.n. (P; Beitel, 1988).
was
This species described by Cavanilles Polypodium
first as peltatuin in
name
However, was
1802. his not universally adopted by
later pteridologists,
whom
many
of accepted the later name, Polypodium polylepis Roem. ex Kunze
(exceptions include Christensen, 1938; Weatherby, 1944; Knobloch and Cor-
and
Although
rell, 1962; Stolze, 1981). the epithet peltatum available and
is
has
within genus Polypodium,
priority the
transfer to Pleopeltis preclud-
its
is
P
ed by the existence of an Old World taxon, peltata ex Alderw.
Scort. (1909,
Dep. synonym
Bull. Agric, Indes Neerl.27:4), a of Microsorium sarawakense
(Baker) Ching (Holttum, 1968). At glance, van Alderwerelt van Rosen-
first
name nomen me
nudum,
burgh's appears to be a but as pointed out to by
David names
Lellinger comm.), the published paper were
(pers. in this vali-
dated by indirect reference on p. 1 to the author's earlier book on Malayan
ferns (Alderwerelt van Rosenburgh,
1908).
Given
that the epithet peltata unavailable in the genus Pleopeltis, have
is
I
P
name
adopted predominantly Mexican The
the polylepis for this taxon. typ-
basionym Polypodium Roemer Kunze
ification of the polylepis ex compli-
is
however, by none
cated, the fact that apparently of the three syntypes (see
may
above) cited in the original description has survived. Neotypification
prove and
necessary, but only after further study searches for extant, original
material have been completed. This will be addressed in a future paper.
A
name
second issue concerns the lectotypification of the Polypodium pel-
tatum According
Cav. to the original description, the type material (two sheets
was
in the Cavanilles collection in Madrid; Fig. collected in the Marianas
1)
who
Islands (now Guam) by Luis Nee. Nee was one of two botanists accom-
panied the 1789-1794 Malaspina expedition Peru and Ecuador, Mexico,
to
and Marianas comm.). The
California, finally to the Pajaron, pers, plants
(S.
were sent periodically the port of Cadiz in southern Spain before eventual
to
transport Madrid.
to
The type material of Polypodium peltatum problematic for two reasons.
is
member
First, no of the Pleopeltis macrocarpa group currently occurs in
Guam,
the type indicated by Cavanilles. Second, photographs of the
locality
type material and detailed measurements of the specimens (provided by San-
ma-
tiago Pajaron, Universidad Complutense, Madrid), revealed that the type
terial contains at least two species. Each sheet contains several plants and,
with any
unfortunately, few of the labels can be reliably associated particular
Guam
The on 476120 lA)
plant. localities indicated the labels of sheet (Fig. are
(ex insulis marianas) and Ecuador (monte San Antonio, Quito), whereas the
localities on sheet 476121 IB) are both in Ecuador (San Antonio and
(Fig.
Guaranda). specimens on both sheets revealed that most
Inspection of the
plants are indeed the Mexican Pleopeltis polylepis, whereas a few are appar-
P
P members macro-
ently macrocarpa. The one of only two of the
latter is
.
AMERICAN FERN JOURNAL: VOLUME NUMBER
78 85
3 (1995)
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79
common
hand
the other
knowledge
Mexico. Thus, most
of the tvpe material
Malaspina was Mex
expedition
in
most
ico. reasonable assume
It IS to that the specimens
came
mixed
between
the time of collection and the time
c
Nevertheless, Nee's material must be taken
as type; there
specimens from 476120
sheet (the one above the lower
ri
lA) has been chosen
as lectotype.
circumscribed
(Hooper,
1994), polvlepis consists of
P.
varieties
nomenclature
Pleopeltis polylepis var. erythrolepis (Weath.) Wendt, Amer. Fern.
70:9.
J.
1980. Polypodium
erythrolepis Weath., Contr. Gray Herb. 65:11. 1922.
Phlebodium
erythrolepis (Weath.) Conz., Fl. Tax. Mex. 1:95. 1946. Pleo-
peltis erythrolepis (Weath.) Serm., Webbia 1968.— Mex-
Pic. 23:189. Type:
Chihuahua,
ico, Portrero [Potrero] Peak, Cold Cliffs, Pringle 825 (holotype,
GH!; isotypes, GH!, LL, NY!, UC!,
US!).
Pleopeltis polylepis var. interjecta (Weath.) E.A. Hooper, comb. nov. Poly-
podium
peltatum Cav. interjectum Weath., Amer. Fern
var. 34:17. 1944.
J.
macrocarpa
Pleopeltis (Bory ex
Willd.) Kaulf. var. interjecta (Weath.) A.R.
Smith, Amer. Fern 70:26. 1980; interjecta (Weath.) Mickel &
P. Beitel,
J.
New
Mem.
York Hot. Card. 46:287-288. 1988.—Type: Guatemala, Chimal-
Tecpam
tenango, Cerro de near Santa Elena, 2700 m, Standley 60957
(F!).
This variety occurs in northern Central America (mainly Guatemala) and
southern Mexico Oaxaca and was
(mainly Chiapas). originally described
as
It
a variety of Polypodium peltatum by Weatherby then
(1944), transferred
to
Pleopeltis as a variety of macrocarpa (Smith, 1980), and finally elevated to
P.
species rank by Mickel and Most authors commented on
Beitel (1988].
re-
its
semblance on one hand and macrocarpa on
to polylepis the to the other,
P. P.
but each emphasized different characteristics used to separate these taxa. For
new
example, Weatherby
in the original description, (1944) differentiated his
R
variety from macrocarpa because has laminar
entire erose-serrulate)
(vs.
it
scales and rhizome scales occluded cell luminae. In contrast, Smith
vi^ith
(1980) classified interjecta as a variety of macrocarpa, because he considered
-R
the and number between two and
similarity in scale size the (small sparse
more
relative to polylepis] to be consistent than the differences in scale
P.
margin used by Weatherby. Finally, Mickel and Beitel (1988) apparently con-
P
sidered the taxon distinct enough from both polylepis and macrocarpa to
P.
P
be was
recognized and with
as a separate species, stated that affinity
its
macrocarpa. Despite a recent morphometric survey of the macrocarpa group
P.
which
(Hooper, 1994), morphological data alone failed to resolve of these three
VOLUME NUMBER
AMERICAN FERN JOURNAL:
80 85
3 [1995)
taxonomic treatments correct, because there are morphological features that
is
support each
one.
A
E
survey of isozyme variability within the macrocarpa group [Hooper,
1994} revealed very high levels of similarity between population sam-
allelic
and The
ples oi interjecta polylepis. average genetic identity value (Nei's
P. I)
R R
among
and
interjecta, polylepis var. polylepis, polylepis var. erythrolepis
was more
a value typical of conspecific plant populations than of con-
0.97,
and
generic species (Soltis Soltis, 1990). Conversely, the genetic identities be-
R
tween interjecta and other members of the group, including macrocarpa,
were nearly 0.81. Electrophoretic analysis of isozymes using starch gel elec-
all
trophoresis therefore provided strong evidence that interjecta should be treated
as a variety of polylepis, rather than as a separate species or as a variety of
P.
R
macrocarpa.
R
Biogeographical data lend further support to this alignment. Within the
macrocarpa group, all but one species are restricted to one of two centers of
species diversity for the group, one based in southern Mexico and northern
America and macro-
Central the other in southern Central America. Pleopeltis
carpa occurs in the southern region (and also extends to the Greater Antilles,
R
South America, and Old and
parts of the World); whereas, poly-
interjecta
lepis both occur in the northern region. Moreover, within the northern region,
R
America and
the ranges of interjecta (northern Central southern Mexico),
R
and and
polylepis var. polylepis (central northeastern Mexico), polylepis var.
somewhat
erythrolepis (northwestern Mexico) There however,
are
distinct. are,
which
regions of overlap within can be assign an individual to
difficult to
it
one or another variety with certainty see Wendt, 1980). Such a geograph-
(e.g.,
more
ical pattern is typical of plant varieties (or subspecies) than plant species.
Given
the inconsistency of the morphological features and the correspon-
R
dence and
of genetic geographical data, polylepis here described as a
is
species with three varieties distributed throughout Mexico and northern Cen-
The R
America. most
tral distinctive of the three polylepis var. interjecta,
is
which
differentiated from the others by narrowly leaves nar-
is elliptic (vs.
its
mm
rowly on
oblanceolate); smaller abaxial laminar scales in diameter
(0.5
mm);
average vs. 0.6 non-overlapping abaxial laminar scales overlapping);
(vs.
conspicuously blackened abaxial costae green erythrolepis] or occa-
[vs. (var.
sionally blackened and conspicuously black-centered soral
(var. polylepis]];
scales with occluded cell luminae brown- or black-centered with clear cell
(vs.
luminae).
The two more from
other varieties of polylepis are difficult to differentiate
P.
A
one morphometric members each
another. analysis of representative of
(Hooper, 1994) revealed that, on average, var. erythrolepis has longer stipes
(about equal to the blade length vs. <V4 the blade length in var. polylepis];
wider
leaves (about one-fifth the blade length one-tenth polylepis];
vs. in var.
larger spores (55 jxm on average vs. 51 pim in var. polylepis]; and an abaxial
costa that is green (vs. occasionally blackened in var. polylepis]. Also, as point-
Wendt
ed by
out (1980), the abaxial laminar scales of mature var. erythrolepis
NEW
HOOPER: COMBINATIONS
IN PLEOPELTIS
81
more
densely more
imbricate, and
ovate-lanceolate
a<
and
with margins more
that are dissected than
in var
Acknowledgments
am
I grateful to Christopher Haufler for his guidance and support and for helpful comments on
the manuscript; to Alan Smith, George Yatskievych, and David Lellinger advice on
for typification
and
nomenclatural matters concerning who
Pleopeltis polylepis; to Santiago Pajardn (Madrid) en-
me
thusiastically provided with detailed information on
the type material of Pleopeltis polylepis;
and
to the curators of the following herbaria for loan of specimens for this project: G, MO, NY,
F,
UC, US. This project was supported by NSF Improvement
in part Dissertation Grant #BSR-9122855
and The
University of Kansas General Research Fund allocation #3114.
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