Phegopteris excelsior N. R. Patel & A. V. Gilman, 2019

Patel, Nikisha R., Fawcett, Susan & Gilman, Arthur V., 2019, Phegopteris excelsior (Thelypteridaceae): A New Species of North American Tetraploid Beech Fern, Novon, A Journal for Botanical Nomenclature 27 (4), pp. 211-218 : 214-216

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°45.07171 ' N, 72°3.631 ' W, in upland Thuja occidentalis forest with Phegopteris connectilis , Gymnocarpium dryopteris (L.) Newman & Parathelypteris noveboracensis (L.) Ching, confirmed as tetraploid by flow cytometry, 8 July 2018, A. V. Gilman 18022 (holotype, VT! ; isotypes, BRIT!, DAO!, MAINE!, MICH!, NEBC!, NHA!, 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 proportione plerumque 5 (vs. 4) atque sporarum longitudine mediocri 64 μ m (vs. 55 μ m) distinguitur.

Long-lived, terrestrial, perennial, leptosporangiate ferns with an apomictic life cycle. Roots fibrous, blackish. Rhizome terete, subterranean, long-creeping, branching to form loose colonies, dull blackish brown, smooth, with few, scattered, ovate scales with elongate cells. Fronds monomorphic, deciduous, (37–)50–60(– 70) cm. Stipes spreading-erect to erect, (185–)280–370(–445) mm, stramineous; vestiture of stipes, rachides, and costae composed of both scales and hairs; scales stramineous to palecastaneous, basally affixed, lanceolate to ovate, to 1.5 X 5 mm, especially abundant, overlapping, pale colored and wide (up to 50 cells wide) on newly developing, tightly coiled croziers but more scattered, 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. Laminae ± broadly deltate, especially when pressed, widest at base, length (170–)225–280(–440) mm, breadth (144–)206–256(–290) mm, usually ca. 1.05X as long as wide, tapering to an acuminate, shallowly crenulate tip; pinnate-pinnatifid to bipinnatepinnatifid; 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 triangular lobes, then to rounded lobes, finally to low crenations; proximal pair of pinnae (72–)103–128(–145) mm X (18.0–)22.0–28.0(–36.5) mm, widest at or below middle, on average 0.2X as 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 acroscopically, 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 μ m, ranging 53–75 μ m. Gametophyte: antheridia functional. Chromosomes n = 120 in both gametophytic and sporophytic tissues.

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 epipetric); soils are often loam or fine sandy loam of circumneutral reaction. Three current populations in Vermont occur on soils described as having pH 5.1–7.3 in the upper stratum, and a fourth population is on soil with pH 4.5–6.5 (NRCS, 2018). Wherry (1921) found P. connectilis to be indifferent to soil reaction, but P. excelsior appears to favor circumneutral soils.

Etymology. The epithet is a Latin comparative adjective meaning “higher” or “taller” and refers to the habit of the species, which is usually taller than Phegopteris connectilis .

Notes. Phegopteris excelsior is an apomict of allopolyploid origin, putatively involving the most morphologically 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 μ m long, ranging 53–75 μ m, whereas triploid P. connectilis spores average 55 μ m long, ranging 43–69 μ m, and diploid P. connectilis spores average 42 μ m long, ranging 25–48 μ m. Phegopteris excelsior also differs from P. connectilis in its nuclear DNA sequences and metabolic enzymes.

Paratypes. CANADA. Nova Scotia: Cape Breton, Great Bras d’ Or, Victoria Co., Baddeck , 2–24 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) . Québec: Laval, St. Francois , mosaic des buttes sèches et dépressions humides sur/dans lesquelles dominant respectivement les érables à sucre ou argenté, 4 June 2013, Claude & Munger 13-116 ( MT) ; Lanaudière, RCM Mattawinie, St. Michele-des-Saintes , sous-bois humides, 24 June 1955, Fr. Louis-Alphonse s.n. ( MT) ; Estrie, RCM Memphrémagog, Lake Memphremagog , Gibraltar , rich wet woods, 5 Aug. 1903, Churchill s.n. ( GH) ; Montérégie, 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 [= Cinq-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. 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) .

Figures

Figure 2. A–C. 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.) Fée (Gilman 2K082, VT). D–F. 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.

Figure 3. Range of Phegopteris excelsior N. R. Patel & A. V. Gilman, based on localities of specimens examined and created using Simplemappr (Shorthouse, 2010).