ArticlePDF Available

Phegopteris excelsior (Thelypteridaceae): A New Species of North American Tetraploid Beech Fern


Abstract and Figures

Since the 1970s, an apomictic tetraploid beech fern (genus Phegopteris (C. Presl) Fée) has been known in northeastern North America. Previously published isozyme data suggest that this lineage is of allopolyploid origin involving long beech fern (P. con-nectilis (Michx.) Watt.) but not broad beech fern (P. hexagonoptera (Michx.) Fée), as originally hypothesized. Its second progenitor remains unknown. We performed a principal components analysis of the apo-mict and its North American congeners to elucidate morphological differences between them. We recognize the apomictic tetraploid at specific rank as P. excelsior N. R. Patel & A. V. Gilman and provide an illustration, a range map, a list of exsiccatae, and a key to Phegopteris species of North America.
Content may be subject to copyright.
Phegopteris excelsior (Thelypteridaceae): A New Species of North
American Tetraploid Beech Fern
Nikisha R. Patel,
*Susan Fawcett,
and Arthur V. Gilman
Pringle Herbarium, Department of Plant Biology, 111 Jeffords Hall, University of Vermont,
63 Carrigan Drive, Burlington, Vermont 05405, U.S.A.
Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Rd.,
Unit 3043, Storrs, Connecticut 06269, U.S.A.
*Author for correspondence:
ABSTRACT. Since the 1970s, an apomictic tetraploid
beech fern (genus Phegopteris (C. Presl) F´ee) has been
known in northeastern North America. Previously
published isozyme data suggest that this lineage is of
allopolyploid origin involving long beech fern (P.con-
nectilis (Michx.) Watt.) but not broad beech fern
(P. hexagonoptera (Michx.) F´ee), as originally hypoth-
esized. Its second progenitor remains unknown. We
performed a principal components analysis of the apo-
mict and its North American congeners to elucidate
morphological differences between them. We recognize
the apomictic tetraploid at specific rank as P. excelsior
N. R. Patel & A. V. Gilman and provide an illustration, a
range map, a list of exsiccatae, and a key to Phegopteris
species of North America.
Key words: Allopolyploid, apogamy, apomixis, cryptic
species, hybrid speciation, Phegopteris, Thelypteridaceae.
The genus Phegopteris (C. Presl) F´ee as currently
recognized includes five species in North America,
Europe, and Asia (Holttum, 1969; Jermy & Paul,
1993; Smith, 1993; Kim et al., 2004; Lin & Smith,
2013; Fraser-Jenkins et al., 2015; Almeida et al., 2016).
These are P. connectilis (Michx.) Watt, P. hexagonop-
tera (Michx.) F´ee, P. decursive-pinnata (H. C. Hall) F´ee,
P. koreana B. Y. Sun & C. H. Kim, and P. tibetica
Of these, Phegopteris connectilis has the widest dis-
tribution, known across North America, Europe, and
Asia, and ranging from montane Taiwan (Lin & Smith,
2013) to slightly north of the Arctic Circle in Europe
(Tolmachev, 1995) and Alaska (Smith, 1993). It is
known primarily as a triploid (Manton, 1950; L¨ove &
ove, 1961, 1976; Mulligan et al., 1972; Mulligan &
Cody, 1979; Smith, 1993; Ivanova & Piekos-Mirkowa,
2003), which has an apomictic life cycle (Manton, 1950;
Mulligan et al., 1972) with premeiotic endomitosis
(sensu Grusz, 2016). The base chromosome number
in this group is 30; being apomictic, both sporophytic
and gametophytic tissues of triploid P. connectilis have
90 chromosomes (n52n590). There is also a diploid
(2n560), sexual race of P. connectilis in central Japan
(Hirabayashi, 1969; Matsumoto, 1982; Matsumoto &
Yano, 1989). With its multiple ploidies and reproduc-
tive modes, P. connectilis constitutes a species complex
with circumpolar distribution.
Phegopteris hexagonoptera, endemic to eastern North
America, is a sexual diploid (Britton, 1953; Wagner,
1955; Smith, 1993). Two other species are confined to
Asia: P. koreana, endemic to Korea, is an apomictic
tetraploid (4n5120; Kim et al., 2004), and P. tibetica,
widespread across China, Nepal, and India (Lin &
Smith, 2013; Fraser-Jenkins et al., 2015), is so far
without information on ploidy or reproductive biology.
The fifth species, P. decursive-pinnata, is widely distrib-
uted in China, Japan, Korea, and Vietnam (Lin & Smith,
2013), and includes diploid, triploid, and tetraploid
cytotypes (Mitui, 1976; Masuyama, 1979, 1986). This
species was recently reported as naturalized in the south-
eastern United States (Florez-Parra & Keener, 2016).
Mulligan et al. (1972) reported an apomictic tetra-
ploid beech fern (n52n5120), discovered by L. Cinq-
Mars at Rougemont, near Montreal, Quebec, and grown
in cultivation at the Agriculture Canada Central Exper-
iment Farm in Ottawa. In addition to investigating its
chromosome complement, Mulligan et al. (1972) qual-
itatively scored characters associated with blade shape,
shape and color of scales on the abaxial surface of
fronds, and extent of rachis wings for several specimens
of this plant and of the two beech ferns native to eastern
North America, Phegopteris connectilis and P. hexago-
noptera. They concluded that the tetraploid was likely
an allopolyploid derived from a hybridization event
between these two, both of which co-occurred with
the putative hybrid at Rougemont, and hypothesized
that the event involved a haploid egg from P. hexago-
noptera and a triploid sperm from P. connectilis. Such a
hybrid, with unbalanced genomes, would fail at normal
meiosis but could bypass normal meiosis via premeiotic
endomitosis to achieve a successful apomictic life cycle
doi: 10.3417/2019409 NOVON 27: 211218.
(Evans, 1969). Later, similar tetraploids were found in
Nova Scotia and New Brunswick, but, given their re-
semblance to P. connectilis, Mulligan and Cody (1979)
included these tetraploids in a broad concept of that
While the morphology of the tetraploid apomict is
suggestive of a mixture of genomes inherited from
Phegopteris connectilis and P. hexagonoptera, that hy-
pothesis was not corroborated by evidence from molec-
ular data. Driscoll et al. (2003) examined six isozymes
from populations in Vermont and found similar mobility
between the isozymes of P. connectilis and those of the
tetraploid but limited similarity in mobility between
those of the tetraploid and P. hexagonoptera. Driscoll
et al. (2003) also carried out a morphological analysis,
including more characters than used by Mulligan et al.
(1972), which also suggested significantly more simi-
larity between the tetraploid and P. connectilis than
between the tetraploid and P. hexagonoptera. Conse-
quently, Driscoll et al. (2003) suggested that the tetra-
ploid may have a hybrid origin involving P. connectilis
but not P. hexagonoptera. Recently, Patel (2018) pre-
sented plastid data that also suggested shared maternal
origins between P. connectilis diploids, triploids, and
this tetraploid, on the basis of identical rps4-trnS and
psbA sequences. Furthermore, both isozyme data in
Driscoll et al. (2003), and biparentally inherited nuclear
markers (Patel, unpublished data), demonstrate hetero-
zygosity, suggesting again that the apomictic tetraploid
is an allopolyploid with P. connectilis as one progenitor
and an unknown species as the other.
Cryptic species abound among ferns, and many such
lineages have been discovered in groups in which
hybridization and apomixis are prevalent (Paris et al.,
1989; Adjie et al., 2007). Allopolyploids, both sexual
and apomictic, are often difficult to distinguish mor-
phologically from their progenitors (Barrington et al.,
1989) or other closely related species. The main prob-
lems posed by cryptic taxa are: (1) the uncertainty of
positive identification and (2) the difficulty of commu-
nication regarding them. With the North American
tetraploid beech fern now characterized by chromosome
number, metabolic enzymes, DNA sequences, and prob-
able maternal ancestry, we address the first problem by
undertaking additional morphological study to charac-
terize it, as best possible, for field and herbarium iden-
tification, and by providing a key and description. The
second problem we address by recognizing the tetraploid
as a new species and providing a name, Phegopteris
excelsior N. R. Patel & A. V. Gilman.
We studied Phegopteris connectilis from across its
North American range, some specimens from Europe,
and both triploid and diploid specimens from Japan,
revising collections at GH, MICH, MT, NEBC, NY, UC,
and VT. We also sampled P. hexagonoptera from the
northeastern and midwestern United States. Included in
our sample were two tetraploids with documented chro-
mosome numbers, including one collection (Sherk &
Cinq-Mars 437, MICH) from the original Rougemont
station, and one from Nova Scotia verified by Cody
(Cody 20242, MICH), both indicated in the principal
components analysis (PCA). Additional putative spec-
imens of tetraploids field-collected by Gilman or seen in
regional herbaria were identified on the characters
provided by Driscoll et al. (2003). We scored 19
quantitative morphological characters (Table 1). We
performed a PCA on 57 samples (Appendix 1), scoring
19 characters ranging from features of scales to those of
pinnae. We implemented the PCA in R v. 3.4.4 using
the package ggplot2 (Wickham, 2016). Our analysis
included accessions of P. connectilis 3x,P. connectilis
2x,P. hexagonoptera, and the known or putative tetra-
ploids, hereafter referred to as P. excelsior. Spores were
measured from four collections of P. excelsior, two of
triploid P. connectilis and one of diploid P. connectilis;
30 spores were collected and measured when possible,
though for two specimens of P. excelsior, 15 and 20 were
counted, respectively.
In the morphological PCA involving Phegopteris
connectilis (2xand 3x), P. hexagonoptera, and P. ex-
celsior, we found substantial overlap among all three
clusters, with diploid and triploid P. connectilis clus-
tering together. The clusters of points representing P.
excelsior are partly intermediate between P. connectilis
and P. hexagonoptera (Fig. 1). In the analysis, the points
representing the holotype and the specimens verified
as tetraploid by Mulligan et al. (1972) are within the
confidence interval of P. excelsior, slightly closer to the
P. connectilis cluster than to the P. hexagonoptera
The first and second principal components accounted
for the largest proportion of variance in the analysis
(66.3%; Fig. 1). The characters with strongest weight
based on eigenvalues were the length of the first pinna
and the length of the second pinna.
Our PCA shows the tetraploid in a generally inter-
mediate position between Phegopteris connectilis and
P. hexagonoptera (Fig. 1), which would support the orig-
inal hypothesis that it was the product of a hybrid event
between those two species. However, knowing that
isozyme data indicate P. hexagonoptera is not a pro-
genitor, we also find support for our alternative
212 Novon
Table 1. Characters scored for principal components analysis (PCA).
1. Length of stipe
2. Length of blade
3. Length of gap between two lowest pinna pairs
4. Number of pinna pairs, including those diminished to lobes at summit of blade
5. Length of basal pinna
6. Number of basiscopic pinnules on basal pinna, including those diminished to lobes at tip of pinnule
7. Length of suprabasal pinna
8. Number of basiscopic pinnules on suprabasal pinna, including attenuating distal segments
9. Width of basal pinna, widest point
10. Width of suprabasal pinna, widest point
11. Number of pinnules on a 5-cm segment near middle of the third pinna
12. Distance from base of sinus to pinna rachis (measured on basiscopic side of largest pinnule)
13. Length of largest pinnule measured along midvein from base of sinus to tip
14. Width of largest pinnule measured from sinus base to sinus base
15. Width of largest pinnule measured 2 mm from tip
16. Number of sori on largest pinnule (including any on tissue below sinuses)
17. Distance from center of sorus to margin, largest pinnule, first basiscopic sorus above base of sinus
18. Number of sporangia per sorus, largest pinnule, first basiscopic sorus above base of sinus
19. Number of indurated cells in annulus in a randomly selected sporangium
Figure 1. Principal components analysis (PCA) of Phegopteris connectilis (Michx.) Watt., P. hexagonoptera (Michx.) F´ee, and
P. excelsior N. R. Patel & A. V. Gilman. Two diploid P. connectilis from Japan are indicated with the number 2. The holotype for
P. excelsior,Gilman 18021 (VT), is indicated with the letter T, and the specimens Sherk & Cinq-Mars 437 (MICH) and Cody 20242
(MICH), plants originally discussed by Mulligan et al. (1972) and verified by chromosome counts, are indicated by the letter C.
Volume 27, Number 4
Patel et al. 213
Phegopteris excelsior (Thelypteridaceae)
hypothesis. The tetraploid shares more overlap with
P. connectilis than with P. hexagonoptera in the PCA,
and similarities with the latter taxon are driven in part by
overall larger size. Although its second presumed pro-
genitor is missing, Driscoll et al. (2003) and our PCA
suggest that the parent could be even taller than
P. excelsior, have narrower basal pinnae, and in general
have more exaggerated P. connectilis features than
any P. hexagonoptera features, assuming that the
morphology of the tetraploid is intermediate between
its progenitors.
The taxonomic rank of apomictic lineages has varied,
especially in angiosperms, but Majesk´y et al. (2017)
recommend recognition of allopolyploid apomicts at the
rank of species, and, in ferns, sexual allopolyploids are
usually so treated (see examples in Grusz, 2016).
Mulligan and Cody (1979) preferred to retain the tet-
raploid as part of Phegopteris connectilis, pointing to-
ward the cryptic nature of its morphology. However, it
clearly shares only a portion of its genome with triploid
P. connectilis and our results indicate that the morpho-
logical distinctions are subtle but consistent. Together,
these factors provide substantial justification for recog-
nition at species rank (H¨orandl, 2018).
We have examined images of Michauxs collections of
Polypodium connectile Michx. from Canada, and Poly-
podium hexagonopterum Michx. from the southeastern
United States, both at the Museum of Natural His-
tory, Paris (P not seen, photos at HUH!; see links in
Blackwell et al., 2018). These specimens were noted as
types of their respective names by Morton (1967). The
specimen of Polypodium connectile clearly conforms to
the triploid Phegopteris connectilis and the specimen of
Polypodium hexagonopterum to the diploid Phegopteris
hexagonoptera. We have also seen an image of the
lectotype, chosen by Parris and lectotypified by Jonsell
and Jarvis (1994), of Polypodium phegopteris L., a
heterotypic synonym of Phegopteris connectilis. That
specimen is in the Clifford Herbarium at the Natural
History Museum, London (BM, image!), and exhibits
morphology consistent with the triploid Phegopteris
connectilis. We are not aware of any other heterotypic
synonyms of P. connectilis s.l. and recognize the tetra-
ploid apomictic beech fern of northeastern North Amer-
ica as a heretofore unnamed, new species.
Phegopteris excelsior N. R. Patel & A. V. Gilman,
sp. nov. TYPE: U.S.A. Vermont: Caledonia Co., St.
Johnsbury, E side of Goss Hollow Rd. near the
Sleeper River, 44°45.071719N, 72°3.6319W, in
upland Thuja occidentalis forest with Phegopteris
connectilis,Gymnocarpium dryopteris (L.) Newman
&Parathelypteris noveboracensis (L.) Ching, con-
firmed as tetraploid by flow cytometry, 8 July 2018,
A. V. Gilman 18022 (holotype, VT!; isotypes,
NY!, UC!, US!). Figure 2.
Phegopteris excelsior N. R. Patel & A. V. Gilman inter
congeneros Americae borealis P. connectili (Michx.) Watt
simillima, sed ab ea frondium magnitudine majore, lamina
ambitu triangulari (vs. ovata), pinnis proximalibus minus
declinatis et angustioribus longitudinis cum latitudine propor-
tione plerumque 5 (vs. 4) atque sporarum longitudine mediocri
64 mm (vs. 55 mm) distinguitur.
Long-lived, terrestrial, perennial, leptosporangiate
ferns with an apomictic life cycle. Roots fibrous, black-
ish. Rhizome terete, subterranean, long-creeping,
branching to form loose colonies, dull blackish
brown, smooth, with few, scattered, ovate scales
with elongate cells. Fronds monomorphic, decidu-
ous, (37)5060(70) cm. Stipes spreading-erect to
erect, (185)280370(445) mm, stramineous; ves-
titure of stipes, rachides, and costae composed of
both scales and hairs; scales stramineous to pale-
castaneous, basally affixed, lanceolate to ovate, to
1.5 35 mm, especially abundant, overlapping, pale
colored and wide (up to 50 cells wide) on newly
developing, tightly coiled croziers but more scat-
tered, smaller, and darker colored on mature frond,
often fugacious; vestiture also includes smaller,
narrow scales 2 to 3 cells wide with edges and
common, spreading, hyaline, acicular hairs. Lami-
nae 6broadly deltate, especially when pressed,
widest at base, length (170)225280(440) mm,
breadth (144)206256(290) mm, usually ca.
1.053as long as wide, tapering to an acuminate,
shallowly crenulate tip; pinnate-pinnatifid to bipinnate-
pinnatifid; ultimate segments entire, crenate, or very
shallowly lobed; vestiture of laminar surfaces only of
hyaline acicular hairs. Pinnae 21 to 39 pairs, average
29 pairs, proximal ones narrowly lanceolate, distal ones
elongate-triangular, gradually reduced to broadly trian-
gular lobes, then to rounded lobes, finally to low
crenations; proximal pair of pinnae (72)103
128(145) mm 3(18.0)22.028.0(36.5) mm,
widest at or below middle, on average 0.23as wide
as long, in life slightly deflexed, not basiscopically
winged to rachis, acroscopically winged but wings not
confluent with those of next pinna pair; suprabasal
pinnae winged to rachis both basiscopically and ac-
roscopically, wings confluent. Sori exindusiate, 0 to
33/pinnule, average 15/pinnule, with 1 to 22, average
15, sporangia, subterminal on vein branches, round to
slightly oblong; sporangia glabrous or with 1 to several
scattered hyaline acicular hairs; annulus vertical, with
12 to 15 indurated cells. Spores reniform, monolete,
averaging 64 mm, ranging 5375 mm. Gametophyte:
antheridia functional. Chromosomes n5120 in both
gametophytic and sporophytic tissues.
214 Novon
Figure 2. AC. Habits. A. Phegopteris excelsior N. R. Patel & A. V. Gilman (Gilman 98067 & Lambert, VT). B.
Phegopteris connectilis (Michx.) Watt. (Gilman 2K123, VT). C. Phegopteris hexagonoptera (Michx.) F´ee (Gilman 2K082, VT).
DF. Close-ups of basal pinnae. D. Phegopteris connectilis (Gilman 2K123, VT). E. Phegopteris excelsior (Gilman 98067
& Lambert, VT). F. Phegopteris hexagonoptera (House 289434, UC). The approximate basal pinnae length:width ratio for
P. hexagonoptera is 3:1, for P. connectilis 4:1, and for P. excelsior 5:1. The basal pinnae of P. connectilis and P. excelsior are
usually widest below the middle, and those of P. connectilis are usually widest above the middle.
Volume 27, Number 4
Patel et al. 215
Phegopteris excelsior (Thelypteridaceae)
Range and habitat. Phegopteris excelsior is known
from Nova Scotia and New Brunswick west to southern
Quebec, south to central New England and eastern New
York (Fig. 3). Phegopteris excelsior generally grows in
deciduous or coniferous forests often comprising tree
species that prefer calcareous soils (e.g., Acer saccharum
Marshall, Thuja occidentalis L.).Local topography is often
sloping, near but not immediately along small streams or
small rivers (not within the annual flood zone), not upper
montane or alpine. Microsites are terrestrial (not epipe-
tric); soils are often loam or fine sandy loam of circum-
neutral reaction. Three current populations in Vermont
occur on soils described as having pH 5.17.3 in the
upper stratum, and a fourth population is on soil with pH
4.56.5 (NRCS, 2018). Wherry (1921) found P. connec-
tilis to be indifferent to soil reaction, but P. excelsior
appears to favor circumneutral soils.
Etymology. The epithet is a Latin comparative
adjective meaning higheror tallerand refers to
the habit of the species, which is usually taller than
Phegopteris connectilis.
Notes. Phegopteris excelsior is an apomict of allo-
polyploid origin, putatively involving the most morpho-
logically similar taxon, P. connectilis, as a progenitor.
The most salient characters are the larger overall size of
its fronds, blades that are more triangular, especially
notable when pressed flat (those of P. connectilis when
pressed flat are teardrop shaped with more or less
elongate tips and rounded bases), and proximal pinnae
that are slightly less downward-directed and narrower,
the width-to-length ratio typically being 1:5 versus 1:4
in P. connectilis. Among cryptic characters, spore size is
useful in distinguishing the tetraploid P. excelsior from
both diploid and triploid cytotypes of P. connectilis.
Phegopteris excelsior spores average 64 mm long, rang-
ing 5375 mm, whereas triploid P. connectilis spores
average 55 mm long, ranging 4369 mm, and diploid
P. connectilis spores average 42 mm long, ranging
2548 mm. Phegopteris excelsior also differs from
P. connectilis in its nuclear DNA sequences and metabolic
Paratypes. CANADA. Nova Scotia: Cape Breton, Great
Bras dOr, Victoria Co., Baddeck, 224 Aug. 1946, Scamman
4124 (GH); Kings Co., Kentville Ravine, 19 Oct. 1980, Hersey
& Newell s.n. (GH); Kings Co., Lower Blomidon, coniferous
wooded slope, 14 Aug. 1971, Cody 20242 (MICH); Pictou Co.,
Pictou, 8 mi. N of old Hwy. 4 on rd. to W Branch River John,
rich moist mixed woods, 3 July 1973, Cody 23302 (MICH).
Qu´ebec: Laval, St. Francois, mosaic des buttes s`eches et
epressions humides sur/dans lesquelles dominant respective-
ment les ´erables `a sucre ou argent ´e, 4 June 2013, Claude &
Munger 13-116 (MT); Lanaudi`ere, RCM Mattawinie, St.
Michele-des-Saintes, sous-bois humides, 24 June 1955, Fr.
Louis-Alphonse s.n. (MT); Estrie, RCM Memphr´emagog, Lake
Memphremagog, Gibraltar, rich wet woods, 5 Aug. 1903,
Churchill s.n. (GH); Mont´er´egie, RCM Rouville, Rougemont,
N side, large clump along stream in woods at 600-ft. elevation,
7 July 1965, Sherk & Cinq-Mars 437 (MICH); RCM Rouville,
Rougemont, [ex horto Central Experiment Farm, Ottawa], Cody
21216 [5Cinq-Mars No. 3] (DAO). U.S.A. Connecticut:
Hartford Co., Windsor, Rainbow, 14 Aug. 1905, Weatherby s.n.
(NEBC). Maine: Aroostook Co., Mars Hill township, N slope of
Mars Hill, 28 July 2004, Gilman 04104 (VT); Franklin Co.,
Strong, 20 July 1966, Seymour 24090 (VT); Hancock Co.,
Great Pond, Dow Pines Recreation Area, E end of Great Pond,
small cedar swamp, 19 June 2008, Gilman 08030 & Famous
(VT); Kennebec Co., Manchester, Allen Hill, rich woodlands,
15 June 1999, Gilman s.n. (VT); Knox Co., Washington, along
logging rd. on the N slope of Patrick Mtn., 29 June 1998,
Gilman 98067 & Lambert (VT); Oxford Co., Bethel, 31 Aug.
Figure 3. Range of Phegopteris excelsior N. R. Patel & A. V. Gilman, based on localities of specimens examined and created
using Simplemappr (Shorthouse, 2010).
216 Novon
1926, Wheeler s.n. (NEBC); Piscataquis Co., [Eliotsville], Ship
Pond [Lake Onawa], 1897, Brown s.n. (UC); Waldo Co.,
[Lincolnville], N shore of Megunticook Lake, wet depression
in cut-over mixed coniferous hardwood forest, 7 Aug. 1951,
Friesner 24499 (MICH); Washington Co., T29 MD, rich open
woods, 12 Aug. 1939, Knowlton s.n. (NEBC). Massachusetts:
Essex Co., Essex, 11 Aug. 1877, Robinson s.n. (GH); Franklin
Co., Northfield, 7 Oct. 1935, Smith & Hodgdon s.n. (Planta
Exsiccata Grayana No. 604: GH). New Hampshire: Rockingham
Co., North Hampton, June 1896, Eaton s.n. (GH). New York:
Delaware Co., s.d., Gilbert s.n. (GH). Vermont: Bennington Co.,
Dorset, 1904, Terry s.n. (VT); Caledonia Co., Orleans Co.,
Westmore, Willoughby, 10 Sep. 1904, Kennedy s.n. (NEBC);
Washington Co., Northfield, along woods rd., S end of Paine
Mtn., 2 Sep. 1993, Gilman 93257 (VT); 29 Aug. 2001, Driscoll
10 (VT).
1. Blades of fronds elongate, widest toward the middle . . .......................P. decursive-pinnata (H. C. Hall) F´ee
19. Blades of fronds widest at the base.
2. Blades of fronds usually slightly wider than long; all pinnae, including proximal pair, winged to rachis; proximal
pinnae (2)33as long as wide .............................................P. hexagonoptera (Michx.) F ´ee
29. Blades of fronds longer than wide; pinnae winged to rachis except proximal pair not winged to rachis (rarely, more
than one proximal pinna pair not winged in P. connectilis); proximal pinnae 453as long as wide.
3. Blade outline ovate, proximal pinnae strongly declined and adaxially inflexed, average 43as long as wide;
spore length averaging 55 65.4 mm......................................P. connectilis (Michx.) Watt
39. Blade outline triangular, proximal pinnae slightly to moderately declined and adaxially inflexed, average
53as long as wide; spore length averaging 64 64.6 mm.........P. excelsior N. R. Patel & A. V. Gilman
Acknowledgments. We thank current and past
members of the Barrington Lab at the University of
Vermont, particularly David Barrington, Heather Dris-
coll, Michael Sundue, Cathy Paris, and Weston Testo for
discussions and manuscript review; Morgan Southgate
confirmed the ploidy level of the type by flow cytometry.
We also thank the Pringle Herbarium (VT) for facilities
and helpful staff, including Eunice Froeliger, for arrang-
ing loans, and the curators and staff of other herbaria
including Chuck Davis, Lisa Standley, and Walter
Kittredge (HUH including GH and NEBC), Matt
Pace, Robbin Moran, and Lucy Klebieko (NY), Anton
Reznicek (MICH), Alan Smith (UC), and Heather Cole
(DAO). We thank Sadamu Matsumoto for his contribution
of specimens and karyological information (NMNS). We
also thank Bruce Baldwin, Alan Smith, and an anony-
mous reviewer for helpful comments on the manuscript.
Literature Cited
Adjie, B., S. Masuyama, H. Ishikawa & Y. Watano. 2007.
Independent origins of tetraploid cryptic species in the fern
Ceratopteris thalictroides. J. Pl. Res. 120: 129138.
Almeida, T. E., S. Hennequin, H. Schneider, A. R. Smith,
J. A. Nogueira Batista, A. J. Ramalho, K. Proite, et al. 2016.
Toward a phylogenetic generic classification of Thelypter-
idaceae: Additional sampling suggests alteration of neotrop-
ical taxa and further study of paleotropical genera. Molec.
Phylogenet. Evol. 94: 688700.
Barrington, D. S., C. H. Haufler & C. R. Werth. 1989.
Hybridization, reticulation, and species concepts in the
ferns. Amer. Fern J. 79: 5564.
Blackwell, A. H., P. D. McMillan & C. W. Blackwell. 2018.
Andr´e Michauxs American plant collections 17851796.
Phytoneuron 2018-12: 112.
Britton, D. M. 1953. Chromosome studies in ferns. Amer.
J. Bot. 40: 575583.
Driscoll, H. E., D. S. Barrington & A. V. Gilman. 2003. A
reexamination of the apogamous tetraploid Phegopteris (The-
lypteridaceae) from northeastern North America. Rhodora
105: 309321.
Evans, A. M. 1969. Problems of apomixis and the treatment of
agamic complexes. BioScience 19: 708711.
Florez-Parra, S. & B. R. Keener. 2016. Phegopteris decursive-
pinnata (Thelypteridaceae), new to the Alabama (USA) flora.
J. Bot. Res. Inst. Tex. 10: 501503.
Fraser-Jenkins, C. R., D. R. Kandel & S. Pariyar. 2015. Ferns
and Fern-allies of Nepal, Vol. 1. National Herbarium and
Plant Laboratories, Department of Plant Resources, Ministry
of Forests and Soil Conservation, Kathmandu.
Grusz, A. L. 2016. A current perspective on apomixis in ferns.
J. Syst. Evol. 54: 656665.
Hirabayashi, H. 1969. Chromosome numbers in several spe-
cies of the Aspidiaceae. J. Jap. Bot. 44: 113119.
Holttum, R. E. 1969. Studies in the family Thelypteridaceae.
The genera Phegopteris, Pseudophegopteris, and Macrothe-
lypteris. Blumea 17: 532.
orandl, E. 2018. The classification of asexual organisms: Old
myths, new facts, and a novel pluralistic approach. Taxon
67: 10661081.
Ivanova, D. & H. Piekos-Mirkowa. 2003. Chromosome num-
bers of Polish ferns. Acta Biol. Cracov., Ser. Bot. 45:
Jermy, A. C. & A. M. Paul. 1993. Phegopteris.P.18in T. G.
Tutin, N. A. Burgess, A. O. Chater, J. R. Edmonson, V. H.
Heywood, D. M. Moore, D. H. Valentine, et al. (editors),
Flora Europaea, 2nd ed., Vol. 1: Psilotaceae to Platanaceae.
Cambridge University Press, Cambridge.
Jonsell, B. & C. E. Jarvis. 1994. Lectotypifications of Linnaean
names for Flora Nordica, Vol. 1 (Lycopodiaceae Papaver-
aceae). Nordic J. Bot. 14: 145164.
Kim, C. H., B.-Y. Sun & S. H. Park. 2004. A new species of
Phegopteris (Thelypteridaceae). Novon 14: 440443.
Lin, L. & A. R. Smith. 2013. Phegopteris. Pp. 342344 in
Z. Y. Wu, P. H. Raven & D. Y. Hong (editors), Flora of China,
Vols. 23, Lycopodiaceae through Polypodiaceae. Science
Press, Beijing; Missouri Botanical Garden Press, St. Louis.
ove, ´
A. & D. L¨ove. 1961. Some chromosome numbers of
Icelandic ferns and fern-allies. Amer. Fern J. 51: 127128.
ove, ´
A. & D. L¨ove. 1976. IOPB chromosome number report
LIII. Taxon 25: 486.
Majesk´y, L., F. Krahulec & R. J. Va ˇsut. 2017. How apomictic
taxa are treated in current taxonomy: A review. Taxon 66:
Manton, I. 1950. Problems of Cytology and Evolution in the
Pteridophyta. Cambridge University Press, Cambridge.
Volume 27, Number 4
Patel et al. 217
Phegopteris excelsior (Thelypteridaceae)
Masuyama, S. 1979. Reproductive biology of the fern Phegopteris
decursive-pinnata: I. The dissimilar systems of the diploids and
tetraploids. Bot. Mag. (Tokyo) 92: 275289.
Masuyama, S. 1986. Reproductive biology of the fern Phegop-
teris decursive-pinnata: II. Genetic analysis of self-sterility in
diploids. Bot. Mag. (Tokyo) 99: 107121.
Matsumoto, S. 1982. Distribution patterns of two reproductive
types of Phegopteris connectilis in eastern Japan. Bull Natl.
Sci. Mus. Nat. Sci., Tokyo, B 8: 101110.
Matsumoto, S. & Y. Yano. 1989. The invasion of the sexual and
apogamous types of Phegopteris connectilis in an avalanched
region on Mt. Fuji. Ann. Tsukuba Bot. Gard. 8: 3746.
Mitui, K. 1976. Chromosome studies on Japanese ferns (5). Bull.
Nippon Dental Univ. 5: 131140. doi:10.14983/00000142.
Morton, C. 1967. The fern herbarium of Andr ´e Michaux. Amer.
Fern J. 57: 166184.
Mulligan, G. A. & W. J. Cody. 1979. Chromosome numbers in
Canadian Phegopteris. Canad. J. Bot. 57: 18151819.
Mulligan, G. A., L. Cinq-Mars & W. J. Cody. 1972. Natural
interspecific hybridization sexual and apogamous species
of Phegopteris ee. Canad. J. Bot. 50: 12951300.
NRCS (National Resources Conservation Service). 2018. Ver-
mont Soil Survey. ,
app/WebSoilSurvey.aspx., accessed 10 September 2019.
Paris, C. A., F. S. Wagner & W. H. Wagner. 1989. Cryptic
species, species delimitation, and taxonomic practice in the
homosporous ferns. Amer. Fern J. 79: 4654.
Patel, N. R. 2018. Apomixis, Hybridization, and Biodiversity in
Ferns: Insights from Genera Phegopteris and Polystichum.
Ph.D. Thesis, University of Vermont, Burlington.
Shorthouse, D. P. 2010. SimpleMappr, an online tool to produce
publication-quality point maps. ,,
accessed 10 September 2019.
Smith, A. R. 1993. Phegopteris. Pp. 221222 in Flora of North
America Editorial Committee (editors), Flora of North Amer-
ica North of Mexico, Vol. 2: Pteridophytes and Gymno-
sperms. Oxford University Press, New York and Oxford.
Tolmachev, A. I. 1995. Flora of the Russian Arctic, Vol. 1:
PolypodiaceaeGramineae. First English Edition. The Uni-
versity of Alberta Press, Edmonton.
Wagner, W. H., Jr. 1955. Cytotaxonomic observations on North
American ferns. Rhodora 57: 219240.
Wherry, E. T. 1921. The soil reactions of the ferns of woods and
swamps. Amer. Fern J. 11: 516.
Wickham, H. 2016. ggplot2: Elegant Graphics for Data Anal-
ysis. Springer-Verlag, New York. ,,
accessed 10 September 2019.
Appendix 1. Specimens measured for principal components
analysis (PCA). AVG refers to the private herbarium of Arthur
V. Gilman, which is not listed in Index Herbariorum.
Phegopteris connectilis. CANADA. Labrador: Perret
Trickle, Potter & Brierly s.n. (GH). Newfoundland: Mt.
Moriah, Fernald, Long & Dunbar s.n. (GH). Ontario:
Thunder Bay, Tryon, Tryon & Faber 4931 (GH). Prince
Edward Island: Charlottetown, Fernald & St. John
s.n. (GH). Quebec: Magadalen Islands, St. John s.n.
(GH). GREENLAND. Godthaab Fjord, Porsild s.n. (GH).
U.S.A. Alaska: Kuskokwim, Drury s.n. (GH); Juneau, Scam-
man 1532 (GH); Mt. McKinley, Vierek s.n. (GH). Maine:
Westmanland, Seymour 23195 (VT). Michigan: Mackinaw Co.,
Fawcett 300 (MICH, VT); Marquette Co., Harrison s.n. (GH);
Eaton Co., Wagner 63068 (GH). New Hampshire: Colebrook,
Pease 10,473 (NEBC). Vermont: Marshfield, Gilman 01032
(AVG); Waterford, Gilman 96087 (AVG); Northfield, Gilman
96132 (AVG); Danville, Gilman 96137 (AVG); St. Johnsbury,
Gilman 96286 (AVG); Wallingford, Wilmot 127 (VT). Wisconsin:
Solon Spring, Somerville 3413 (GH). JAPAN. Mt. Futago,
Boufford 23464 (confirmed diploid) (A); Mt. Kiso, Matsumoto
130924-07 (confirmed diploid) (GH); Senjogahara Moor,
Boufford 23382 (confirmed triploid) (A); Mt. Fuji, M. Furuse
s.n. (confirmed triploid) (A).
Phegopteris excelsior. CANADA. Nova Scotia: Lower Blo-
midon, Cody 20242 (MICH); Kings Co., Hersey & Newell
s.n. (GH). Quebec: Hatley, Churchill s.n. (GH); Gibraltar,
Churchill s.n. (GH); Hatley, Knowlton s.n. (GH); St. Gregoire,
Rouleau et al. s.n. (GH); Mt. Rougemont, Sherk & Cinq-Mars 437
ex cult #65374 (MICH). U.S.A. Connecticut: Windsor, Clark
s.n. (larger of twospecimens on the sheet) (NEBC). Maine: Mars
Hill, Gilman 04104 (VT); Cooper, Gilman 06050 (AVG); Molun-
kus, Gilman 2K199 (AVG); Washington, Gilman 96087 (AVG);
Bucksport, Gilman 97261 (AVG); Litchfield, Gilman 98018
(AVG); Strong, Seymour 24090 (VT). New York: Delaware
Co., B. D. Gilbert s.n. (GH). Vermont: Cabot, Gilman 01142
(AVG); St. Johnsbury,Gilman 18021 (holotype) (VT); St. Johns-
bury, Gilman 96061 (AVG); East Montpelier, Gilman 96118
(AVG); Waterford, Gilman 96248 (AVG); St. Johnsbury, Rooney
s.n. (VT); Dorset, Terry s.n. (VT).
Phegopteris hexagonoptera. U.S.A. Illinois: Jackson Co., S.
R. Hill 34847 (VT). Maine: Washington, Gilman 97127
(AVG). Massachusetts: Belchertown, H. Churchill s.n.
(VT). New York: Lake George, Evans s.n. (VT). Vermont:
South Hero, Gilman 14057 (AVG); Charlotte, Gilman 2K082
(AVG); Charlotte, Gilman 2K083 (AVG); Charlotte, Gilman
93145 (AVG); Shelburne, Gilman 98232 (AVG). Washington,
D.C.: Corwin s.n. (VT).
218 Novon
ISSN 1055-3177 (PRINT); ISSN 1945-6174 (ONLINE)
... The Thelypteridaceae contains two subfamilies, Phegopteridoideae and Thelypteridoideae, with the former containing three genera, including Phego pteris, with seven species (PPG I 2016;Patel et al. 2019;Fujiwara et al. 2021). Laminal wings at the base of most pinnae are characteristic of Phegopteris and are present on the fossil fern leaf from Driftwood Canyon. ...
... The distal portion of the fern blade in P. connectilis (Figure 2a), and less so in P. excelsior, narrows abruptly to a pinnatifid tip, whereas, in P. hexagonoptera, the blade narrows evenly toward the tip as seen in the fossil (Figure 2b). Patel et al. (2019) separated P. connectilis from P. excelsior on the basis of the "tear-shaped" outline of the whole blade versus the broadly deltoid shape of P. excelsior and from P. hexagonoptera by the prominent basioscopically (downward) pointing and asymmetric lowermost pair of pinnae in that species, with P. con nectilis pinnae symmetrical and P. excelsior intermediate between these states. It is unclear whether the lowermost pair of pinnae is present on the fossil beech fern, and the attachment of the lowermost pinna to the rachis is poorly preserved (Figure 2b). ...
... It is unclear whether the lowermost pair of pinnae is present on the fossil beech fern, and the attachment of the lowermost pinna to the rachis is poorly preserved (Figure 2b). However, if the lowermost pinna is interpreted as part of the lowermost pinna pair, it is symmetrical, as seen in P. con nectilis (Patel et al. 2019), but lacks the basioscopic orientation (Figure 2a,b) typical of the P. connectilis group. It is unclear whether laminal wings joined this pinna to the one above it or whether the rachis was unwinged, as seen in P. connectilis and P. excelsior (Patel et al. 2019). ...
Full-text available
Ferns are important components of the biodiversity of wet forests across Canada, and the fossil record offers insights into the origins of fern diversity and biogeography. In 1967, Driftwood Canyon Provincial Park in north-central British Columbia was declared an Eocene Epoch plant, insect, fish, bird, and mammal fossil site of national scientific significance to preserve the Driftwood Creek fossil beds. The fossil plants from this important fossil site remain largely unknown. Here, a first record of a beech fern from the Eocene of British Columbia—morphologically comparable to the Phegopteris connectilis group—is illustrated, further revealing the past biodiversity of ancient British Columbia. The absence of sori and other key anatomical characters prevents definitive identification. Today, the circumpolar to temperate species Northern Beech Fern (Phegopteris connectilis) is widespread across British Columbia, occurring in wet coniferous forests; other members of the P. connectilis group also occur in temperate climates.
... Phegopteris connectilis is unique among the Park's ferns in being an apomictic triploid that produces mostly unreduced spores, which germinate to form triploid gametophytes that, in turn, give rise to new sporophytes without fertilization (Patel, Fawcett, and Gilman, 2019). This trait is most commonly found in species that occupy drought-prone habitats (Grusz et al., 2021), and it is very unusual to see it so well developed in a mesic species like P. connectilis. ...
... These two hybrids regularly form discrete populations in the absence of one or both parents, suggesting they may be experiencing incipient apomixis. The origin of triploid Phegopteris connectilis has not been ascertained, but hybridity has not been ruled out (Patel, Fawcett, and Gilman, 2019). Thus, hybrid origins (and possibly triploidy) may be driving the evolution of apomixis in all three of these mesic lineages. ...
Full-text available
Glacier National Park encompasses over one million acres in the mountains of northwestern Montana, along the United StatesCanada border. Our survey of online databases indicates that the earliest extant fern and lycophyte collections from this area were taken by Robert S. Williams in 1892. In the summer of 1919, Paul C. Standley, a botanist with the United States National Museum, conducted a survey of the flora of the newly created Park and recorded 39 species of ferns and lycophytes. In 2002, a revised flora for the Park by Peter Lesica increased this number to 61. Here we summarize 130 years of collections-based research on the ferns and lycophytes of Glacier National Park, documenting how our understanding of the flora has changed through time. In the summer of 2019, the lead author conducted a field survey to relocate as many ferns and lycophytes as possible within park boundaries. In parallel, we scoured herbarium online portals and databases for high-resolution digitized specimen images to confirm or refute historical vouchers of ferns and lycophytes collected from the Park. In a few cases, specimen loans were requested from herbaria to confirm our determinations. The results from our combined field and online herbarium studies are presented here. Of the 61 taxa recognized by Lesica in 2002, we were able to confirm all but seven. In sum, we recognize here a total of 71 fern and lycophyte taxa for the Park. Most previously unreported taxa belong to Botrychium, a genus that has seen a flurry of recent taxonomic work by co-author Farrar and collaborators. These new data are presented here together with updated nomenclature and discussion to provide a current taxonomic account of the fourteen fern and lycophyte families known to occur in Glacier National Park. We anticipate this study will provide a useful foundation for further investigations in the Park.
... Compared to seed plants, ferns have a very high prevalence of polyploidy and reticulate evolution ( Barrington et al. 1989;Paris et al. 1989;Otto and Whitton 2000;Otto and Whitton 2000). Such genomic changes can contribute to cryptic variation by altering niche requirements or offspring viability (Otto 2007;Southgate et al. 2019;Masuyama et al. 2002), yet be essentially phenotypically invisible ( Patel et al. 2019). ...
Full-text available
Cryptic species are present throughout the tree of life. They are especially prevalent in ferns, because of processes such hybridization, polyploidy, and reticulate evolution. In addition, the morphological simple body plan of ferns limits phenotypic variation and makes it difficult to detect crypic species in ferns without molecular work. The model fern genus Ceratopteris has long been suspected to harbor cryptic diversity, specifically in the highly polymorphic C. thalictroides. Yet no studies have included samples from throughout the pan-tropical range of Ceratopteris or utilized genomic sequencing, making it difficult to assess the full extent of cryptic variation within this genus. Here, we present the first multilocus phylogeny of the genus using reduced representation genomic sequencing (RADseq) and examine population structure, phylogenetic relationships, and ploidy level variation. We recover similar species relationships found in previous studies, find support for a named cryptic species as genetically distinct, and identify a novel putative species from within C. thalictroides sensu latu in Central and South America.
Cryptic species are present throughout the tree of life. They are especially prevalent in ferns, because of processes such hybridization, polyploidy, and reticulate evolution. In addition, the simple morphology of ferns limits phenotypic variation and makes it difficult to detect cryptic species. The model fern genus Ceratopteris has long been suspected to harbor cryptic diversity, in particular within the highly polymorphic C. thalictroides. Yet no studies have included samples from throughout its pan-tropical range or utilized genomic sequencing, making it difficult to assess the full extent of cryptic variation within this genus. Here, we present the first multilocus phylogeny of the genus using reduced representation genomic sequencing (RADseq) and examine population structure, phylogenetic relationships, and ploidy level variation. We recover similar species relationships found in previous studies, find support for the cryptic species C. gaudichaudii as genetically distinct, and identify a novel genomic variation within two of the mostly broadly distributed species in the genus, C. thalictroides and C. cornuta. Finally, we detail the utility of our approach for working on cryptic, reticulate groups of ferns. Specifically, it does not require a reference genome, of which there are very few available for ferns. Next generation sequencing like RADseq is a cost-effective way to obtain the thousands of nuclear markers needed untangle the many species complexes present in ferns.
Full-text available
Organisms reproducing via asexuality harbor a great diversity of lineages, morphotypes and ecotypes. However, classification of asexual taxa does not fit into contemporary species concepts, and hence the diversity of apomictic plant complexes is not well reflected in taxonomy. Plants reproducing via apomixis (i.e., asexual seed formation = agamospermy) exemplify the theoretical and practical problems of classification. Obligately asexual organisms do not form reproductive communities, but they do constitute ancestor-descendant lineages. From the conceptual side, evolutionary lineage concepts would fit best for species delimitation. Recent research showed that these lineages are not necessarily threatened by rapid extinction and do have persistence in time and space. Facultative sexuality and low levels of residual recombination counteract the accumulation of deleterious mutations due to the lack of recombination (Muller’s ratchet). Apomictic lineages do have adaptive potential, which is demonstrated by the ability to occupy large distribution areas and to experience ecological niche shifts. The challenge for classification of asexual lineages, however, is to find operational criteria for species delimitation. Current practices of species delimitation can be grouped into four main principles: (1) the sexuals-first principle means that obligate sexual progenitor species are classified separately from their apomictic derivatives. (2) The all-in-one principle merges sexual progenitors and highly facultative apomictic derivatives into one species, whereby the apomicts often represent autopolyploids without differentiated phenotypes. (3) The cluster concept applies to allopolyploid complexes with facultative apomixis and a huge diversity of genotypes and morphotypes; here the main genetic clusters are treated as species. (4) Almost obligate apomictic lineages are being classified as agamospecies. The four principles reflect quite well evolutionary traits and diversity of lineages. Finally, a recommendation for a workflow is given, following this gradient from obligate sexuality to obligate apomixis. © International Association for Plant Taxonomy (IAPT) 2018, all rights reserved
Full-text available
Gametophytic apomixis (asexual seed formation without syngamy of female and male gametes) is a highly interesting mechanism for researchers in plant biotechnology, genetics, evolutionary biology, and taxonomy. Apomixis evolved repeatedly and independently in the evolution of multiple genera. It is an effective reproduction barrier and, consequently, conserved apomictic genotypes may become overrepresented in nature. Apomictic plants may easily colonize free niches with only one or a few individuals and outcompete outcrossing plants. In spite of the indisputable pros of asexual reproduction, apomixis also has several cons. One of the most commonly mentioned is the accumulation of deleterious mutations in asexual lineages and decreased genetic variation. However, apomicts in general can be genetically highly diverse. The most common sources of this variation are the accumulation of mutations, hybridization with sexual plants, and facultative apomixis. Facultative apomicts are highly variable in their level of residual sexuality, which increases their genotypic and phenotypic variation. Even in the case of obligate apomicts, gene flow is possible due to functional male meiosis and the production of viable pollen grains by apomicts. Apomixis occurs in plant genera in which hybridization together with polyploidization play an important role in diversification and causes severe problems in taxonomy. How to accommodate apomictic taxa in taxonomic treatments, and understanding what should and what should not be referred to as a species are intriguing questions. This review aims to provide an overview of the main characteristics of “apomictic genera” and the approaches used to treat apomictic taxa within these genera. To achieve this aim, the review was divided into several parts. Firstly, the distinctive features of apomictic reproduction and apomictic taxa are described together with issues related to the taxonomic evaluation of apomictic taxa. The second part discusses approaches in the known apomictic genera, and the final part presents the authors’ view on important points, which need to be taken into account in the classification of apomictic taxa.
Full-text available
This review provides a synopsis of apogamous reproduction in ferns and highlights important progress made in recent studies of fern apomixis. First, a summary of the apomictic fern life cycle is provided, distinguishing between two pathways to diploid spore production that have been documented in apomictic ferns (premeiotic endomitosis and meiotic first division restitution) and briefly discussing the evolutionary implications of each. Next, recent trends in fern apomixis research are discussed, exposing a shift in focus from the observation and characterization of apomixis in ferns to more integrated studies of the evolutionary and ecological implications of this reproductive mode. Peer-reviewed contributions from the past decade are then summarized, spanning the identification of new apomictic lineages through to the developmental, phylogenetic, and population genetic insights that have been made in studies of fern apomixis during that time. Gaps in our understanding are also discussed, including the extent and implications of recombinant apomixis in ferns, the possible reversibility of reproductive mode (from apomictic to sexual) in ferns, and the genomic causes and consequences of apomixis in seed free vascular plants. To conclude, future directions for fern apomixis research are proposed in the context of modern technological advances and recent insights from studies of apomixis in other groups.
Full-text available
Thelypteridaceae is one of the largest fern families, having about 950 species and a cosmopolitan distribution but with most species occurring in tropical and subtropical regions. Its generic classification remains controversial, with different authors recognizing from one up to 32 genera. Phylogenetic relationships within the family have not been exhaustively studied, but previous studies have confirmed the monophyly of the lineage. Thus far, sampling has been inadequate for establishing a robust hypothesis of infrafamilial relationships within the family. In order to understand phylogenetic relationships within Thelypteridaceae and thus to improve generic reclassification, we expand the molecular sampling, including new samples of Old World taxa and, especially, many additional neotropical representatives. We also explore the monophyly of exclusively or mostly neotropical genera Amauropelta, Goniopteris, Meniscium, and Steiropteris. Our sampling includes 70 taxa and 121 newly generated sequences from two plastid genomic regions (rps4-trnS and trnL-trnF), plus 71 rps4 and 70 trnL-trnF sequences from GenBank. These data resulted in a concatenated matrix of 1980 molecular characters for 144 taxa. The combined data set was analyzed using maximum parsimony and bayesian inference of phylogeny. Our results are consistent with the general topological structure found in previous studies, including two main lineages within the family: phegopteroid and thelypteroid. The thelypteroid lineage comprises two clades; one of these included the segregates Metathelypteris, Coryphopteris, and Amauropelta (including part of Parathelypteris), whereas the other comprises all segregates of Cyclosorus s.l., such as Goniopteris, Meniscium, and Steiropteris (including Thelypteris polypodioides, previously incertae sedis). The three mainly neotropical segregates were found to be monophyletic but nested in a broadly defined Cyclosorus. The fourth mainly neotropical segregate, Amauropelta, was found to comprise species considered to be part of the Parathelypteris. In Old World thelypteroids, which correspond to nearly half the diversity in the family, an increase in sampling is still needed to resolve relationships and circumscription of genera, particularly in the christelloid clade (i.e., Amphineuron, Chingia, Christella, Pneumatopteris, Pronephrium, and Sphaerostephanos). Based on currently available knowledge, we propose the recognition of 16 genera in the family.
Full-text available
Hybrids and hybrid species are common among ferns, and they account for many of the problems in species definition in the group. Most systematic inquiry into the evolutionary process in ferns has addressed hybrid species, because meaningful explanations of their origins are feasible (Manton, 1950). As a result, complexes of hybrids, hybrid species, and their progenitor species have been popular subjects for experimental work. Here, we address the definition and changing perception of these hybrid species in the light of improvements in the data available to systematists. Once we have established basic definitions, we demonstrate the utility of recent advances in defining hybrid species of ferns. With this orientation, we investigate the status of hybrid species in the context of reigning species concepts. Renewed reproductive interaction between populations or species following a period of isolation characterizes all hybrids; hence hybrids are often spoken of as the products of secondary contact. Hybrids are unique in that they arise when isolating mechanisms fail; thus they are evolutionarily a consequence of the disruption of the divergence process that leads to ordinary (primary) species. Consequently, the hybrid is at once a novelty and a rehash: it is a novel combination of genetic and morphological features already present in its progenitors. These features need not be intermediate: see Grant (1975) on transgressive segregation and Barrington, 1986a. Fern hybrids are predominantly sterile (Knobloch, 1976), though there is a small, disparate set of variously fertile hybrids (in Pteris, Walker, 1958; in Dryopteris, Whittier & Wagner, 1961; in the Cyatheaceae, Conant & Cooper-Driver, 1980). The origin and evolutionary significance of sterile hybrids have been the subject of most
A new species of fern, Phegopteris koreana (Thelypteiidaeeae), was collected from Southern Korea and is described here. Phegopteris koreana is most similar to P. decursive-pinnata morphologically; however, the new species consistently shows discontinuous morphological gaps from the latter in the shape of the fronds, pinnae, and ultimate segments, venation pattern ill ultimate segments, tufted trichomes in the sori, and spore wall sculpturing.
It has been revealed that gametophytes of diploid plants of Phegopteris decursive-pinnata have a low capability for intragametophytic selfing (Masuyama, 1979). In the present study, intergametophytic mating tests were conducted for the self-sterile gametophytes of four diploids to demonstrate the genetic factors responsible for such a low capability for selfing. The results of the tests indicated that the gametophytes carried two or more kinds of recessive embryonic lethal factors which were non-allelic with each other and that the occurrence frequency of the gametophytes with an identical recessive lethal factor was 13% to 27% in the gametophyte families of these four diploids The karyological study of a diploid sporophyte suggested not the tetraploid but the diploid constitution of somatic chromosomes. Based on these data, the diploid inheritance of two or three special deleterious genes with a synergistic interaction responsible for the embryonic lethality was hypothesized to elucidate the self-sterility in the diploids of this species.