A Revision of the Fern Genus Phanerophlebia (Dryopteridaceae)

32 Pages·1996·25.7 MB·English

by  George Yatskievych

THE FERN
A REVISION OF
George
Yatskievych^
GENUS PHANEROPHLEBIA
(DRYOPTERIDACEAE)'
Abstract
riic primarily neolropical fern genus Pbancroplilebla is revised !a\i)noniitall) lo include eight speeies, with a key
and descriptions pro\ ided. Classification of the genus within the Dryopteridaceae reviewed, as are morphology,
is tlie
slelar anatomy, and cytology of the species. The justification for reduction of Phauewphlehia remotispom to a variety
of P. nohilLs is <lis<*ussed. Ihe recently namt^d di[)loid s[)e<'ies, P. gaslouyi^ is contrasted with its telra[)loid derivative,
juglandifoUa, and hybridization and polyploidy within the genus summarized.
P. art?
Phanemphlrhia C. Presl is an enigmatic genus Aside from (jiirsticms of sp(M'ies-level taxonomy.
comprising eight species of tenestrial ferns of the Phancrophldna has also provided problems in ge-
N<'W World tropics and adjacent subtropical neric classification. The distinctness of the group
n^gions. Most pteridologists know about the from Asiatic Cyrtomium and nearly cosmopolitan
little
group because of the rarity with which the species Polystichum has remained controversial and Is
are encoinilered in nature. The genus was revised symptomatic of the geru^ral difficulties of generic
taxonomically by Underwood (1899) and Maxon circumscTiption present the family Dryopterida-
in
(1912), Both of these early studies were based on ceae (and several other pleridophyte families as
in
relatively few In^rbarium specimens and did not ad- well).
equately circumscribe variation in critical morjiho- Tlu* pres<Mit paper Incorporates data from several
many
logical characters, Resulting In subsequent concinnMit studies (Stein el al., 1989; Yatskievych,
&
mis<h>l<^rminations. 1989, 1990, 1992, 1993; Yatskievych Gastony,
new
Th(^ ne^ed for a taxoiiomic study of this genus 1987; Yatskievych el 1988) on aspects of evo-
al.,
was further supported by disagreements and (jues- lution and syslemalics of Phanerophlehia and the
tions raised by the few researchers who have ex- results from field, lu^rbariuni, and greenhouse stud-
amlned
the species In recent years. Smith (1981), ies on llu^ group, in an atleiTipt to refine our un-
Micke] and and An
Beitel (1988), Stolze (1981), in derstanihng of the genus. evolutionary species
their detailed florislic treatments of pteridophytes concept employed, which circumscribes a set of
is
of Chiapas and Oaxaea, Mc^xico, and Guatemala, morphologically (h'fined laxa that are also geneti-
respeetively, each pointed out taxonomic problems cally separated. Gi^nelic separation, bas<*d on var-
group and emphasized
in the different characters lous estimates of genetic similarity, rather than
in <lelint»ating taxa. Tiyon and Tiyon (1982), in th<Mr crossing baniers, has been used, because attempts
American
review of fenis, pointed out th(* confusing at artificial hybri<lization between taxa failed uni-
patlern of mon)hologi<'al variation In the genus and formly (unpublished data). The varietal designation
some
suggesttMl that of the traditionally accepted is us(m] in this paper to denote putatively interfertile
species might be combined, following much-need- morpholypes within a species, which lack sharp
ed, critical, future studit*s. biog<H)graphic discontinuities, and which are sep-
am
' I indebted to Gerald Gastony and other members of the faeults al hidiana L'niversily for their support and
my
gui<lanee during doetoral studies, fhis study also Ix^nefilted from the adviee, data, and reviews of David Harrington,
John Miekel, Hol)l>in Moran, Alan Smith, Rolla and Alice Tryon, David Wagner, Herb and Florence Wagner, and
Mii'hael Windham. Gerald Gastony, Maimel Gonzalez Miehael Crayutn. Bo<»ne Hallberg. Hiehard Hevly, Tom Ranker,
I..,
Greg and (]arol Starr, Eckhard Wollenweber, and Richard Vtbrlhinglon are among those patient souls wlu) put up with
my
The
idiosyneralie field hehavior. curators of the herbaria cited generously provided loans of pertinent specimens.
T
am
Bend
gralehil to Big National Park, Texas Parks and Wildlife Department, and various agencies of the Mexican
government
for generously a|)proving collecting permits for this project, and lo Stephen Koch, Blanca Perez-Garcfa,
Ram6n
and Riba for their exlra(»rdinary help in obtaining permit> in Mexico. This research was sup(>orlcd by granis
from the Indiana University Department of Biology, Indiana University Gradnatf* School, Indiana Academy Science,
of
National Science Foun<lalion (BSR 82-l2f)<'>()), and National Academy of Science (through the Joseph Henry fund,
administered by Sigma Xi, ihe Scientific Research Society). Finally, ihis study could not have been possible without
and my who became my
the love, su})port, involvt^nent of wife Kay, pari of during completion.
life its
2W,
^ Missouri Botanical Garden, VX). Box Louis, Missouri 03166, U.S.A.
St.
Ann. Missouri Hot. Card. 83: 168-199, 1996.
Number 169
Volume Yatskievych
2
83,
Phanerophlebia
Revision
1996 of
unopened
morpho- For spore counts, single, sporangia
arated by only a single, relatively trivial,
character (whose genetic basis remains un- were carefully removed from field-collected (rather
logical
nown than greenhouse-grown), dried pinnae with a dis-
k
)
secting probe and opened in a drop of lactic acid
under microscope. Ten counts from
the dissecting
Methods and Materiai^
were compiled representative
different sori for
Herbarium specimens, including types, were plants from each population. Spore sizes were also
com-
studied from the following collections: A, ARIZ, measured from material in lactic acid, using a
ASC, BH, CAS, CM, CR, CU, DS, ENCB, Gil, pound microscope equipped with an ocular nil-
F,
HAL, IND, K, LL, MEXU, MICH, MO, NY, crometer. Thirty nu^asurements of the long(«st di-
P,
XAL
POM, RSA, TEX, UAMIZ, UC, US, (abbre- mensions of spores from at least five sporangia were
mean
used Holmgren made, from which the and standard dt^viation
viations follow those in et al.,
morphology
Approximately 1400 specimens representing were calculated for each sample. Spore
1990).
670 Phanerophlebia was observed under the compound microscope from
about different collections of
were examined. Additionally, about 260 collections material in lactic acid and from dried material, as
(SEM).
Cyrtomium and Polystichum were examined well as by scanning electron microsco{)y
of for
The observations were carried out using a
comparative purposes. latter
250-MK2
Information from herbarium specimens was sup- Cambridge Stereoscan machine. Dry
SEM
were mounted on aluminum stubs us-
plemented with observations of populations in na- spores
A of 25 populations of Phanerophlebia ing double-sided tape without pretreatment and
ture. total
was located during fieldwork in the southwestern sputter-coated with gold/palladium using a Polaron
E5100
United Mexico, and Costa Rica. In addition unit prior to viewing.
States,
observations and can^fully pressed speci-
to field
Anatomy
MoRFliOLOGY AND
mens, representative plants from each population
common
De-
were transplanted into culture in the
RHIZOMES AND LEAVES
partment Biology greenhouses Indiana Uni-
of at
Rhizomes Phanerophlebia species are dictyo-
phenotypic of
versity for further observation of varia-
Cyrtom-
and anatomically similar those of
stelic to
tion.
Chandra and Nayar
For detailed observations of scale mori:)hology, ium species studied by (1982)
mm
and Gibson They range from 3
small strips of clear tape (Scotch) were used to re- et al. (1984).
pumila 20
move samples from leaves and rhizomes with the in diameter in small plants of P. lo ca.
mm
mm
8-15
aid of forceps and mounted on microscope slides in P. macrosora, but are in adult
Hoyer's medium. Stelar observations were based plants of most species. Rhizomes may be charac-
in
ascending
on direct observation of freehand sections from liv- terized as generally short-repent (erect or
R
and macrosora and pumila), unbrariched (tend-
ing rhizomes. Details of venation patterns epi- in P.
P P
and
dermal morphology were observed from pinnae or ing to branch at maturity in auriculata
pinna pieces cleared using the bleaching proce- umbonata), and deep-seated in the substrate (ex-
P
and sometimes
pumila,
dures summarized by Dilcher (1974). Following de- cept in P. gastonyi, in P.
samples the rhizomes are
hydration and staining with safranin 0, for difi
and
observation of leaf venation were dried flat in a densely covered with scales near the apices
described by Wagner with persistent petiolar bases and adventitious roots
small press similar to that
The mat and
and epidermal samples were mounted on on older portions. dt^nse of p<'tiol(^s
(1976),
microscope slides in Permount, prior to viewing. roots makes the rhizomes appear larger than they
Chromosome counts were made on representa- actually are. Rhizome scales are discussed below,
each population. Young pinnae with devel- under indument.
lives of
oping sporangia were fixed in Farmers solution Leaves (fronds) develop equally from all sides of
(3:
absolute ethanol glacial acetic acid) for meiolic the rhizomes and are clustered near the rhizome
1
:
cm
Sporangia were spread using the standard apices. Mature leaves range in length from 4 in
counts.
P
270 cm They
pumila macrosora. persist
acetocarmine squash technique (Manton, 1950), as to in
P.
modified by Haufler (198S). Cells were ex- for two or more years and eventually die back to
et al.
which There
amined compound microscope and chromo- the petiolar bases, are persistent. is
with a
New
somes were drawn using a camera lucida. no well-defined zone of abscission along tlie peti-
counts or those differing from the literature were oles. The petiolar bases persist for several years,
P
photographed, using Kodak Technical Pan turning hard and "woody" in macrosora, hiii re-
also
maining green and semisucculent, with green in-
filiii^
170
Annals
the
of
Missouri Botanical Garden
lenial tissues, in otlier species. Altlumgh an iodine
was
test not perfoniKMl, these persistent petiolar
bases presumably function as lro[)h()pods (Wagner
&
Jolnison, 1983).
many
Petiole vascularization simpler than
is in
members 4—8
other of the Diyopteridaeeae, and the
—
vascular bundles (mean ananged an
are
6) in
uneven The cuned
ring. petioles are abruptly
at
their bases, so as to orient the leaves vertically,
except in P. macrosora. In this species the petiolar
bases are usually oriented
horizontally for a dis-
5-10
tan(*e of cm, before curving upward, the leaf
bases thus appearing geniculal<». Petioles may be
somewhat
than
shorl<M- or longed' than the laminae,
and
an* scaly (see below) in species.
all
Laminae monomorphic and
are -pinnate (some-
1
times simple gastonyi and
in P. P, pumila), with
alternate pinnae Rachises
(leaflets). are adaxially
lratt\ with the groove more or less confluent with
the costal groove of each pinna, although, prac-
in
tice, this character is usually difficult to assess. The
have
laminat^ (hscrete tenninal piimae, but are not
imparipinnate some
typically in that leaves of
all
species have an even number Such
total of pinnae.
leaves are usually mixed on same
the plant with
those having odd rmmbers of pinnae, and there
is
no morphological evidence
for the existence of
"pscudolerminal" pinnae; no nodes
or articu-
i.e.,
lations an* present at the tip of a rachis to suggest
suppn^ssion of the laminar apex and replace-
its
ment by an adjacent, pinna.
lat(*ral
Pintuu* of species are chartaceous
all to subc^or-
FiguHi Cleared pinnae PhanerophU'hin
1. of species.
—
and have
s shallow, adaxial, costal grooves. aurlculntu {YuLshievych aL 83-10), showing sim-
a. P. et
They range in shape from ovate linear-lanceolate ple, dirhotomous venation and presence of acroscopic,
to —
84^
and conunonly have attetmate apices and asym- basal auricle. b. P. auricidata [Yatskie—vych et aL
68), showing irregular acroscopic lohing. umhon-
r. P.
metrical bases. Pinna bases are normally more de-
&
McCrary
(ltd (Yatshietych 85-05), showing sini|)lc (non-
—
veloped acroscoplcally and
(Fig. acroscopic,
1), anastomosing), (lichotomous v<^nati()n. d. /* gdstonyi
commonly
basal auricles occur in Phanerophlebia (Yatskieiyrh et al. 85-182), showing anastomosing vena-
=
R tion. Scale bar cm.
auriculata, sporadically and 1
in purnila, rarely in
P
nohilis (van nohilLs). Pinna margins spinu-
lose-serrulate, the teeth connected by a narrow,
white, marginal band of hanl tissue, but the density (1979) for Polystichum munitum, and a similar phe-
and
distribution of the nomenon
teetli vary. In P. gastonyi, in Polystichum acrostichoides incisum
(f.
the seiTulations are confined to the distal half of (A. Gray) Gilbert) was attributed by Wagner
et al.
P
each pinna, and
in juglandifolia the density of (1970) environmental and temporal
to factors. In
semilations in proximal portions of the pinnae can Phatierophlchia, is of interest to note that in such
it
P
vary greatly on individual leaves. In rnacrosora, pinnae the lobes each contain one vein has
that
senoilations tend to be somewhat more widely branched from the costa and that the multiseriate
spaced than other species and
in the teeth are often (with respect to the costa) sorl are arranged in a
somewhat
stouter. single series on either side of midvein each
this in
Rare
individuals of most species Such anomalous
(particularly lobe. pinnae provide
indirect evi-
P
Phanerophlebia and
auriculata pumila) have deuce
that the 1 -pinnate leaf dissection in P/mn^r-
som«* heaves with the pitmae deeply incised to lac- ophlehia derived from a more highly dissected
is
on
erate, particularly the acroscopic side (Fig. lb). leaf type.
The same phenomenon
was described by Wcigner Venation Phanerophlebia species anadro-
in
is
Volume Number
2 Yatskievych 171
83,
1996 Revision Phanerophlebia
of
mm
nious (this often diffuull lo observe) and consists less than 2 from the costa, hut the innermost
mm
of numerous, arcuate, secondary veins branching sori are otherwise normally more than 4 from
sequentially from the costa of each pinna (Fig. the costa. This character has been used by some
1).
1^
R
These secondaries branch times before termi- authors to differentiate P. juglandifolia from no-
nating near the pinna margin. There no vein run- van remotispora, but too variable for consis-
bilis is
is
ning parallel to the margins, but there a thick- lent application.
is
ened, narrow band of hard, white tissue along the The sori are more or less cirtrular and in all but
edge, which the veins terminate. Thus, the veins two taxa are covered by an indusium. Presl (1836)
at
do not extend into the marginal serrulations of the noted the absence of an indusium In Phaner-
first
pinnae. The basal 1—2 vein branches do not extend ophlebia juglandifolia (which ne ussed as evKiident^e
\ I
to the margins, instead terminating between the to abgn this species with Polypodium under the
costa and margin. Vein endings are tapered (except generic name Amblia), but nearly all subsequent
those terminating in sori), lacking bulbous thick- workers ignored or dismissed this character until it
was reexamined by Smith Phanerophlebia
enings (1981).
The venation pattern o( Phanerophlebia of two gastonyi, which has been confused with P. jitglan-
is
common
kinds. The most type, which characterizes difolia in the past, is the other species lacking in-
R
taxa except gastonyi, juglandifolia, and dusia. Part of the problem with regard to this char-
all P. P.
nobilis var. remotispora, consists of simple, dichot- acter is that in all of the indusiate species except
R
omously branched secondaries essentially lacking umbonata the indusia are fugacious, shriveling
ma-
anastomoses (Fig. la-c). All of the free-veined taxa and mostly falling off by the time the sorus is
R
can produce rare, marginal anastomoses, and in ture. Thorough examination of sori in these taxa
common
haitiemis these can be fairly (>2 })er pin- will always result in the discovery of at least a few
na, but very irregularly distributed). The ultimate remaining, shriveled indusia, however.
vein-branches in the free-veined taxa rangt* from In those species possessing indusia, these
more roughly
arcuate to nearly straight, but are usually or eph<^meral structures are light tan, peltate,
less parallel to one another. circular in outline, erose-margined, and 0.6-1.1
mm
R
In Phanerophlebia gastonyi, juglandifolia, and in diameter. They are membranous to papei7,
remotispora, the branching secondaiy concolorous, and to slightly c<mcave centrally,
P. nohilis var. flat
1-3 Phanerophlebia umbonata, which has
veins form a regular pattern of series of simple, except in
submarginal anastomoses (Fig. Id). The pattern of firmer, subcoriaceous, persistent indusia with a
umbo
reticulation that of elongate areolae with acute raised, darkened in the center. Indusia of P.
is
apices and bases. There are no free, tertiar)^ veins pumila arc unusual in that the attachment point of
sometimes and
included in the reticulations (as in Cyrtomium), but the receptacle is acentric, the in-
more
most cases the basal branches of the secondaries dusia are often ovate than circular in outline,
in
end l)elow the anastomoses of adjacent, more mar- also of interest that although diploid P. gas-
It is
R
ginal branches, thus appearing enclosed. Although tonyi and its tetraploid derivative, juglandifolia,
there are no clear morphological distinctions be- lack indusia, the rare, sterile, triploid hybrid be-
tween the patterns of reticulation found in the tween llu^ latter taxon and the indusiate P. macro-
R R
closely related gastonyi and juglandifolia on sora has rudimentary, irregular indusia less llian
mm
R
the one hand and those oi nobilis var. remotispora 0.2 in diameter,
on the other, evidence from restriction site poly-
morphisms genomes (Yatskievych
in the chloroplast
SI^ORKS
1988) and the fact that only one of the two
et
al.,
R
varieties of nobilis exhibits reticulate venation Spores of selected Phanerophlebia species were
suggest that this pattern has arisen independently examined cursorily (usually in conjunction with
twice in the genus. those of Cyrtomium) by several earlier authors, but
Sori of Phanerophlebia species are eilh<*r lermi- the first detailed study of spore mor|>hology in the
nal or lateral on the secondar}' veins and are situ- genus appeared as part of the g(^neric treatment for
R
ated in 2—4^ series (sometimes only 1-seriate in Cyrtomium (including Phanerophlebia) in Tryon
The
pumila) between the costa and margin. In P. um- and Tryon s (1982) broad sui-vey of fern genera.
sometimes submar- subsequent discussion Tiyon and Lugardons
bonata, the clustered in
sori
ginally, but otherw^ise they occur in a broad band (1991) sui^vey of fern spores expanded slightly on
R
The
between the costa and each margin. In gastonyi this initial treatment. present account attempts
R
expand upon
and juglandifolia (occasionally also in other spe- to this excellent foundation,
cies) the innermost series of sori may be situated Sporangia contain 64 spores in all fertile taxa
172 Annals
the
of
Garden
Missouri Botanical
n\ 1 1'tcfk tnoiuAvAe and dark brown at niaturily. atf struitures usually assorialrd with term
lliis
SjM»n's fall into three size rlassrs. Those of the dip- (Fig. Such reduced scales are common in the
3).
30^2
\ok\ I^haricmphlehia gastonyi arv fim in \on- Diyopit ridaceae and liave been noted by several
gest (hmension, whereas those of other fertile dip- students of family. Daigoho (1972) believed that
tlu'
and 41-60
loid tetraph)id taxa in the genus are /im. variations in the pattern of cellular orientation and
Spores of P. haUie/Lsls, although seemingly well shapt* made such Irichomes the most stable and
formed, show great variation, even within impoilant
siz(^ in- eharac^ters for infrag<^nerie classification
dividual sporangia, and measure 36—52 ^m. Spore of the 47 sptuies oi Poly um Japan, Ryukyu,
stick in
size IS thus of little use in identifying polyploids, and Taiwan, and applied the name "microscale'' to
P
means who
exe<*pt as a of distinguishing gastonyi them. Viane held trichome morphology
(1986),
from its closest relatives. to be important in classification of Dryopteris spe-
The
exospore in all species is smooth (Fig. 2) cies, adopted tlie name "paleaster" for such hair/
and is covered by a two-layered perispore. The scale inti^rmediates. Moran (1986, 1987), working
thin, irmt*r perispore has a slightly undulate sur- with the related gent^ra Olfersia and Polyhotrya,
fare, often also with widely sc^ittered papillae, coined tlu^ term "proscale'' for them. Smith (1986),
These may
papillae repre^sent th(* rudiments of col- in his monogra[)h of Cydodiunu differentiated re-
umellae that once connected the inner and outer duced scales from acicular and septate glands
liairs
perisporal layers, but actual columellae apparently also found in that genus but declined invent a
to
no The
longer outer layer of ptMispore nauic
exist. is thi'se structures. Barringt(»n (1989), in his
fin-
much
thicker than tlu^ iruier layer and consists of studies of neotropical Polystichum, adopted the
The
inflated, irregularly undulate folds. density and term "microscale'' and noted that most species of
degree of inflation of these folds varies develop- neotropical Polystichum Daigobo's
share<l (1972)
mentally and each
within species. Tlu^y are thus of Metapolystichum type of scale development.
little use in distinguishing among them, althougl The pattern of scale developnuMit in all s[>ecies
the malun* spores of P. macrosora generally have of Phaner()j>hl('l)ia is id<Mitical and is similar that
l<»
few(M' folds than those of other taxa. The surface of seen in the Metapolystichum type of Daigobo
the outer perisporal layer cdso varies from nearly (1972). The reduced scales found to some degree
smooth to rugulose and contains no observable mi- on the abaxial laminar and distal costular surfaces
croperforations. are tan to brownish and appress<ul. The smallest
All fertile sj)ecimens of Phancrophlchia species are uniseriate and api>r()ximately 3 ce^Us long, with
possess at least some sporangia that, at maturity, somewhat flattened cells and thickened endwalls.
contain malformed, a[)parenlly abortive spores of In contrast to the situation described by Daigobo
variable size with th<^ outtT perisporal layer rela- (1972) for Metapolystichum, however, the terminal
tively smooth and the fcdds winglike and uninflated cells of these smallest scales are obtuse, rath<Tthan
These resemble immature
(Fig. 2d). spores in their acutely allcnuatt* (Fig. Larger scales with two or
3).
incom{)let(* perispi)ral deposition and although not more i-ellular series display the mor|)h()logy more
obviously collapsed or shrunken within, they will typical of Metapolystichum scales. In these largtT,
not germinate on agar or soil. Sporangia containing reduced scales the basal 1-2 serif's cells are
iif
such spores are especially frequent in the relativ(dy smaller than the other cells and nearly square
few luTbarium specimens
available oi P. haitieusLs, to rhomboidal in outline. yVbove this base, the body
Whether phenomenon
this has a genetic basis is of l\\e scale is broadened and the individual cells
not presently known, but plants placed under en- are elongate longitudinally. Processes homologous
vironmental stress (such as excess sunlight or high to the lateral lilia of fully developed costal and
temperature) in the gn^enhouse produce such abor- petiolar scah^s are evident near the base of the
first
tive spores with greater frequency than when grown reduced scales, which are otlun-wise entire along
under more
optimal conditions. their margins.
lati'ral
Along
the costae, the rt^luced scales grade
abru|)tly into longer and broader structures usu-
th<^
lNtHiMt:Nr
ally associated with the t(Tm scale. Rtnluc^ed scales
leaves of Phanerophlehia sptH'ies do not possess are best obsened on immature leaves and are ap-
true hairs in the sense that this term is usually parently shed during development or at least easily
applitnl to such epidermal outgrowths in nH»st ferns. abradtvl from niature laminae. Th*^ pinnae of some
P
Inst<*ad, the uniseriat(\ multicellular tricliomes populations of auricuhita and pumila possess
P.
present in all species are in reality reduced scales, tht^ densest covering of reduced scales, but this re-
am]
intergrade complelcly may
witli the larger, pluriseri- tenlion of vivstitun* be du<^ primarily to the
Number 173
Volume 2 Yatskievych
83,
Phanerophlebia
1996 Revision
of
83-87)
Figure Spores of Phanerophlebia species.
2.
—
—
mature ami immature spores. b. R aurkulata {Yatskievych et aL 83-10). c. P. gastonyi {Yatskievych et at. 85-182).
—
&
macrosora McCrary 86-30), with incomplete perispore formation characteristic of nonfunctional
{Yatskievych
d.
P.
=
spores j)resent in some sporangia of al] species. Scale bars 10 /xm.
174
Annals
of the
Garden
Missouri Botanical
and macrosora tend to remain relatively unal-
P.
become
tered at maturity, allliough the eilia al>ra(l-
cd with age. The petiole bases of young leaves hi
species are covered with dense indunumt of
all a
imbricate scales except in gastonyi, wherein the
P.
and
stales are sparser essentially non-overlapping.
P
In macrosora, the dense, chaffy covering of
scales especially persistent, t^ven with age.
is
A
f
Rhizome and
peliolar are concolorous, ex-
s(;ales
cept Phanerophlcbia gastonyi and juglandi-
in
P.
The
foUa. fornuT species has scales with broad,
dark and
centers of sclerified cells narrow, hyaline
margins. In the latter species the darker, central
band
of variabh* width, though defuKvl from
is w(^ll
the correspondingly broader, hyaline margins.
P
Specimens
of macrosora rarely have scales with
slightly dark(*r3 poorly differentiated, central
Othenvise
regions. scales of this species are light
The
tan. remaining taxa produce tan orange-
to
P P
brown and umhomiUi
scales; those of nobilis
arc usually a pronounced orange-brown in color.
Figun^ 3. Representative laminar scales from a single
IIVBHTOIZATION AND POLYPLOIDY
83—
leaf of Plutncrophlehia aiirirulafa {Yalskicvych aL
et
10),
Chromosome
counts Phanerophlcbia species
for
are presented in Table These indicate that the
1.
=
protected habitats in which these plants usually base numlx^r for the genus x 41, a common
is
number
grow.
in the Dryopteridaceae. Representative
The most highly developed scales occur along chron)osom(^ counts had been published previously
the proximal portions of the petioles and on the for most species and appeared to indicate a rcla-
rhizomes. The rhizome and largest petiolar scales lively simple cytological situation in the group, with
are similar in morphology within most species, but less polyploidy and hybridization than typical in
is
the rhizome scales arc usually less variable and Polystichum and other related genera. The
earliest
P
ollcn slightly smaller and more densely ciliate n»poi1s for the genus were diploid counts for um-
along th(Mr margins than those of adjacent petiole honata (Wagner, 1963; Mickel Diploid
1966).
et al.,
bases. The largest rhizome and petiolar scales counts had also been published for P juglandifolia,
mm
P P P P
range In length from 2.S-4.0 in gastonyi to macrosora, nobilis, and rcmotispora (Smith
mm
P &
10-15 Rhizome
in macrosora. scales are Mickel, 1977). Two lelraploid taxa had been
P
ovate to elliptic-lanceolate, but petiolar scales vary identified, auriculata (Reeves, 1978) and
P,
&
from linear to ovate in most species, due to the piimila (Smith Mickel, 1977), and except for a
mixed
gradation of scale types described above. single tetraploid count for a sample tentatively as-
P
P
Exceptions are gastonyi, which has vei7 few nar- cribed otherwise diploid van
to llu^ nobilis re-
&
rower mixed
scales with the sparse, ovate scales motispora (Smith Mickel, 1977, reported as
P. cf.
P
along the petiolar bases, and pumila, which has rcmotispora). there was no evidence of cytological
only linear-fibform petiolar scales except in the heterogeneity in any of the species. The only pres-
very basal portions. ently accepted species which no chromosome
for
P
The
margins of the rhizome and petiolar scales count which known
exists Is hailiensls, is histor-
are ciliate, an<l those of Phanerophlcbia macrosora ically from few collections and presumed
vt^ry
is
are strongly erose-ciliate. In all taxa, there is a ten- extinct at its type locality in Haiti.
P
dency New
for these cilia to break off with age. In counts reported in Table agree with most
1
nobilis, cilia tend to be abraded easily, and a dili- earlier counts for the genus, but document sur-
tlie
gent search with a dissecting microscope nee- prising Phanerophlcbia
is find that juglandifolia, as
essary obst^ve few remaining on
to the scales at traditionally circumscribed, comprises two cyto-
&
rhizome
or leaf maturity. In contrast, th<^ margins types (Yatskievych Gastony, 1987). The previ-
P
of petiolar scales in gastonyi, P. juglandifolia, ously published count from Oaxaca, Mexico (Smith
Volume Number 2 Yatskievych 175
83,
1996 Revision Phanerophlebia
of
Table Chromosome mirtil>ers in Phdnerophlehia. All coiinls are from meiotic malerial. Vouchers for tww eoiints
1.
IND MO,
are aceessioned and with (hiplicales to be distributed elsewhere.
at
Number
of
Vleiotic
Species Bivalents Source
auriculata 82 U.S.A. Arizona; Chochise Co., Bass Canyon, Galiuro Mtn., 3 Jan. 1983,
P.
Yatskievych 83-10; Garden Canyon, Huachuca Mtn., 17 May 1983,
et al.
Yatskievych 83-I6I\ Santa Cruz Co., Sycamore Canyon, Pajarito Mtn.. 30
&
Dec. 1982, Yatskievych Yatskievych 82-273; Yavapai Co. (Reeves, 1978).
New
Mexico: Dona Ana Co., Ice Canyon, Organ Mtn., 21 July 1984, Yat-
skievych 84-68.
et al.
MEXICO. km N
gastonyi 41 Chiapas: ca. 13 of Berrio/abal, 17 July 1985, Yatskievych
P.
&
85-182. Oaxaca: (Smith Mickel, 1977, as juglandifolia). Ve-
et al. P.
km N 29
racruz: 1 of l^as de F'.nricjuez on rd. from Jalapa to Misantla,
&
Sep. 1986, Yatskievych Gastony 86-337.
& COSTA
MEXICO.
juglandifolla 82 Chiapas: (Smith Mickel, 1977, as remotispora).
P. P. cf.
km
RICA. San Jose: 6 S of Hwy. 2 on Hwy. 12 to Santa Marfa de Dota,
&
km SE
15 Mar. 1986, Yatskievych McCrary 86-13, Heredia: 2 of Sacra-
&
mento on Hwy. 114, S slope of Volcan Barva, 18 Mar. 1986, Yatskievych
McCrary
86-31.
COSTA km SE
juglandifolla 1231 RICA. Heredia: 2 of Sacramento on Hwy. 114, S slope of
P.
X &
McCrary
niacrosora Volcan Barva, 18 Mar. 1986, Yatskievych 86-31a.
COSTA km SE
niacrosora 41 RICA. Heredia: 2 of Sacramento on Hwy. 114, S slope of
P.
&
MEXICO.
McCrary
Volcan Barva, 18 Mar. 1986, Yatskievych 86-30.
NE
Oaxaca: 1-2 30
Llano Verde, mi. of Natividad, Dec. 1983,
trail to
NE
83-467; 22 Camino on
Yatskievych et al. mi. of Teotillan del rd. to
&
A
Huautla, 28 Sep. 1986, Yatskievych Crustony 86-329; (Smith Mickel,
1977).
nobilis
P.
W
41 MEXICO. Mexico: 1-2 km E of San Rafael on slope of Vole dn Iztacci-
var. nobilis
huatl, 21 July 1985, Yatskievych al 85-21 Oaxaca: 35 km S of Tlax-
et 1.
&
iaco on Hwy. 125 to Putla, 27 Sep. 1986, Yatskievych Gastony 86-327;
&
(Smith Mickel, 1977, as nobilis).
P.
MEXICO. km N
var. remotispora 41 Chiapas: ca. 13 of Berrio/abal, 17 July 1985, Yatskievych
&
85-186; (Smith Mickel, 1977, as /* remotispora). Hidalgo: 17 mi.
et al.
SW &
May
of Chapulhuacan on Hwy. 85, 4 1983, Yatskievych Wollenweber
SW
km
83-128; 32 of Tamazunchale on Hwy. 85 to Jacala, 22 Dec. 1983,
SW
km
Yatskievych 83-353. Veracruz: ca. 3 of Orizaba on Hwy.
et al.
&
May
150D, Sierra de San Cristobal, 9 1983, Yatskievych Wollenweber
83-158,
&
MEXICO. Oaxaca:
pnniila 82 Chiapas: (Smith Mickel, 1977). Llano de Las Flores,
P.
N
high point on Hwy. 175 of Ixtl^n de Juarez, 13 July 1985, Yatskie-
al
NE
vych et al. 85-139; of Ixtlan de Juarez on old rd. from Cajjulalpan de
Mendez, near junction with newer road Francisco Madero, 19 July
to
I.
& L &
1985, Yatskievych Gonzalez 85-209; (Smith Mickel, 1977).
SW
anihonata 41 MEXICO. Nuevo Leon: of Monterrey on rd. to Valle de San Angel,
P.
&
lower slopes of Mesa de Chipinque, May 1983, Yatskievych Wollenwe-
1
km
ber 83-87; post #29 on Hwy. 58 from Linares to San Roberti). 19 Dec.
W
1983, Yatskievych 83-299; Cola de Caballo, of El Cercado, ca. 20
et al.
mi. S of Monterrey, 4 Jan. 1984, Yatskievych et al, 84-04; Canon de San
km SE
Francisco, Sierra Madre Oriental, ca. 35 of Monterrey, 16 Sep.
&
San
1986, Yatskievych Gastony 86-250. Luis Potosi: (Mickel
el at.,
1966). U.S.A. Texas: Brewster Co., Maple Canyon, Basin, Chisos Mtn.,
&
12 Mar. 1985, Yatskievych McCrary 85-05.
176 Annals
of the
Garden
Missouri Botanical
b
a
« #
<#
I
rm 1^
•
• -.
r\
#
^
•
I
"^^S
%
a
b'
Figure 4. MtMolic preparalions illustrating new chromosome coinils in Phanerophlehia. a, b, photographs; a', h',
— —
&
=
interpretive camera luciila drawings. a. P. ju^ldndifolid. 2n 82 II (Yat.skievych McCrary 86~I3). b. P. juglan-
X = & =
difolia macrosonu 2n 123 {Yatskievych McCrary 86-31a), Scale bars 10
/xni.
I
&
A
Mickel, 1977), applies to the rare diploid taxon stricto. fuilhor novelty was the documentation of
treated as P. gaslonyi in tbt* juesenl work, whereas sterile triploid hybrids (Fig. 4) in a mixed popula-
P
ihe letraploid (*oiint attributed to P. ef. rcmotispora tion of diploid P, rriarrosora an<l letraph)id jug-
by Smith and Miekel known
(1977) applies to the taxon landifolia, the only primar) hybrid in the
(Fig. 4) tieated herein as P, juglandifolia sensu getuis. Thus tht^ cytologieal situation in this small
Number 177
Volume 2 Yatskievych
83,
1996 Revision Phanerophlebia
of
group somewhat more complex than was sug- ata (Fig. These taxa all share identical rhizome
is 6).
gested by earlier studies. and petiolar scale types and overall leaf tnorphol-
As has been noted above, spore size did not ogy. Specimens from some localities where the
prove be a reliable indicator of ploidy in Pha- ranges of these taxa overlap have been misdeter-
to
nerophlebia and was useful only in discriminating mined by earlier workers and a few samples, such
gastonyi from relatives. However, the vari- as those collected by Robert Bye in the Sierra Ma-
P. its
ability of spores in the small sample of P. haitiensLs dre of Chihuahua, Mexico (i.e.. Bye 6989, 7094,
and the apparent high number of malformed spores 7363), were quite difficult to determine* during the
P
taxon suggest hybridization and/or poly- present research. Phanerophlebia auriculata and
in this that
ploidy may have had a role in formation. umbonata share a tendency for rhizomes to branch
its
Measurements of epidermal cells were also with age, a feature not seen in P. nobilis, Biogeo-
P P
somewhat equivocal as a means of documenting graphically, the derivation of auriculata from
P
polyploidy in the genus. Epidermal cells in Pha- nobilis and umbonata also seems reasonable, giv-
known
nerophlebia species are irregular in size and shape, en that these three taxa are the only ones
but are extremely wavy-margined (jigsaw-puzzle- to occur in northern Mexico, However, mixed pop-
piece shaped) surface view Stomates are ulations have not been found in nature.
in (Fig.
5).
As mea-
restricted to the abaxial surface of the pinnae and Phanerophlebia haitiensis. noted above,
are more or less of the polocytic type (sensu Van surements of stomata suggest that this rare taxon is
P
Cotthem, 1970). Although polyploids, such as some sort of polyploid, and its irregular spore size
pumila, generally possess larger epidermal cells on and relatively high rmmber of malformed spores
The
both adaxial and abaxial pinna surfaces, the within- suggest that hybridization involved. iiTegular
is
me
sample variation so high that quantification of patteni of anastomosing venation also leads to
is
these measurements was useless. Measurements of suspect that is of hybrid origin. This taxon is
it
stomates (technically, guard cell lengths) proved to presumed extinct in Haiti (see below, under taxo-
be a more stable means of distinguishing diploid nomic treatment) and was unavailable fi)r labora-
taxa (mean 47.7 ^tm, range 44.9-54.3 /xm) from tory study, so no comparative information is avail-
polyploids (mean 60.8 /xm, range 59.6-63.7 able from cytological, isozymic, or chloroplast
fxm).
What
Measurements from a cleared pinna off? haitiensis genomic studies. is unusual is that no other
within the range of guard cell size in species of Phanerophlebia has ever been recorded
(Fig. 5) fell
how
making imagine
polyploid taxa, a further suggestion that this species from Hispaniola, difficult to
it
a polyploid of some this taxon might be present at a single, isolated site
is sort.
A known
summarizing what
brief discussion in Haiti.
is
Phanerophlebia
about each of the four polyploids in the genus (in- Morphologically, haitiensis is
P
The specimens
eluding Phanerophlebia haitiensis), along with reminiscent of nobilis. few that
between
speculations as the likely parentage of each, exist are intermediate in venation free-
to is
P
presented below. The juglandi- veined variety nobilis and reticulate-veined variety
sterile triploid,
P
X and
remotispora, but haitiensis has smaller leaves
folia
;
P
fewer pinnae than usual for either variety of
is
iifi
and
Phanerophlebia auriculata. This tetraploid oc- nobilis. It is possible that the irregular spores
cupies the northwestern portion of the range of the reduced leaves might have resulted from inhospi-
genus Isozyme studies (Yatskievych, 1990; table environmental conditions, rather than from
(Fig.
6).
&
Yatskievych Gastony, 1987) have indicated that genetic causes, but this would not explain the rel-
probably an allopolyploid, but did not result atively large stomates and the irregularly anasto-
is
it
The
any firm conclusion regarding potential progen- mosing venation. existence of two morj^holog-
in
Guatemala {Beaman
within the genus. These data are, however, ically similar collections from
itors
consistent with speculations that follow. Anal- 3056) and Honduras {Moran 5706) (see under tax-
th(^
DNA
mutations onomic treatment) suggests that further fieldwork in
ysis of chloroplast restriction site
one southern Mexico and Central America may even-
(Yatskievych 1988) sugg(^sted that of
et al., its
P
P
parental species nobilis. Morphoh)gically, tually result in at least j)artial resolution of the
is
and auriculata are very sim- enigma surrounding this taxon.
nobilis var. nobilis P.
and
and occurrence acroscopically au- Phanerophlebia juglandijolia. Yatski(^vych
the rare of
ilar.
P
P
pinnae (otherwise unique Gastony (1987) discussed the two cytotypes consti-
riculate in nobilis to
P
The and
auriculata) reinforces this similarity. oth(^r tuting the traditional taxon juglandifolia as-
name
sjunimen
morphologically similar (Hploid occurring in the certained that the type the
t»f
northern portion of the generic range umbon- agrees with the tetraploid. Morphological characters
is P.