Formal recognition of six subordinate taxa within the South American bracken fern, Pteridium esculentum (P. esculentum subsp. arachnoideum s. l. - Dennstaedtiaceae), based on morphology and geography Author Schwartsburd, Pedro B. Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Av. P. H. Rolfs s. n., Viçosa, MG, Brazil, CEP 36570 - 900 Author Yañez, Agustina Museo Argentino de Ciencias Naturales “ Bernardino Rivadavia ”, CONICET, División Plantas Vasculares, Av. Ángel Gallardo 470 - Piso 2, C 1405 DJR, Ciudad Autónoma de Buenos Aires, Argentina Author Prado, Jefferson Instituto de Botânica, Herbário SP, Cx. P. 68041, São Paulo, SP, Brazil, CEP 04045 - 972 text Phytotaxa 2018 2018-01-05 333 1 22 40 http://dx.doi.org/10.11646/phytotaxa.333.1.2 journal article 10.11646/phytotaxa.333.1.2 1179-3163 13723356 1. Pteridium esculentum (G.Forst.) Cockayne subsp. arachnoideum (Kaulf.) Thomson (2012: 45) s. str. Two varieties are recognized: 1. Margins of sterile laminae regularly transformed into continuous pseudo-indusia; simple distal segments linear, to 3(–4) cm long ............................................................................................................................................................................... var. arachnoideum -. Margins of sterile laminae mostly not transformed into pseudo-indusia and ciliate; simple distal segments triangular elongate, to 1.5 cm long .......................................................................................................................................................... var. paedomorficum FIGURE 3. A–C. Pteridium esculentum subsp. gryphus var. gryphus : A. pinnule ( Gleason 423 ), B. segment, abaxially ( Gleason 423 ), C. segment, cross section, abaxial side up, showing sericeous veins, with lax, arachnoid hairs, and laminar tissue between the veins with farinaceous appearance, fully covered by gnarled hairs ( Gleason 423 ), D–F. Pteridium esculentum subsp. gryphus var. harpianum : D. pinnule (“ B.W. ” 1121 [US-2019769]), E. segment, abaxially ( Barreto 1623 ), F. segment, cross section, abaxial side up, showing veins abaxially nearly glabrous, and laminar tissue between the veins with farinaceous appearance, fully covered by gnarled hairs ( Barreto 1623 ). Drawn by R. Pinto. 1a. Pteridium esculentum (G.Forst.) Cockayne subsp. arachnoideum (Kaulf.) Thomson var. arachnoideum ( Figs. 1D–F, 2 , 6 , 7 ) Pteris arachnoidea Kaulfuss (1824: 190) , nom. cons. Allosorus arachnoideus (Kaulf.) Presl (1836: 153) [as Allosorus arachnoideus (Desv.) C.Presl ]. Pteris aquilina L. var. arachnoidea (Kaulf.) Eaton (1861: 203) . Cincinalis arachnoidea (Kaulf.) Trevisan de Saint-Léon (1874: 31) . Pteridium aquilinum (L.) Kuhn var. esculentum (G.Forst.) Kuhn (1882: 27) f. arachnoideum (Kaulf.) Hieronymus (1909: 246) . Pteridium aquilinum (L.) Kuhn var. arachnoideum (Kaulf.) Brade (1920: 56) . Pteridium arachnoideum (Kaulf.) Maxon (1924: 89) . Filix-foemina aquilina (L.) Farwell (1931: 290) var. arachnoidea (Kaulf.) Farwell (1931: 290) . Pteridium caudatum (L.) Maxon subsp. arachnoideum (Kaulf.) Lellinger (2003: 150) . Lectotype (designated by Schwartsburd et al. 2014: 110 ):— BRAZIL . State unknown: “Habitat in Brasilia”, without date, C.A. de Chamisso s.n. (LE!). = Aspidium brasilianum Presl (1822: 176) , nom. rej. Cystopteris brasiliana (C.Presl) Presl (1836: 93) . Hypolepis brasiliana (C.Presl) Kuhn (1882: 347) . Lectotype (designated by Schwartsburd & Prado 2011 ):— BRAZIL . Rio de Janeiro : “ Ad Rio Janeiro Brasilia legit def.” [In via ad S. João Marcos ad Engenho da Varge, Capit. Rio de Janeiro ], [ March 1818 ], J.B.E. Pohl s.n. [ 3794 ] ( lectotype PRC !, isolectotype W!). = Pteris psittacina Presl (1822: 185) , nom. rej. Allosorus psittacinu s (C.Presl) Presl (1836: 153) [as Allosorus psitaccinus ]. Pteris aquilina L. var. psittacina (C.Presl) Baker (1870: 403) . Pteridium psittacinum (C.Presl) Maxon (1933: 141) . Pteridium aquilinum (L.) Kuhn subsp. psittacinum (C.Presl) Christensen (1934: 166) . Lectotype (designated by Schwartsburd & Prado 2011 ):— BRAZIL . Rio de Janeiro : “ Ad Rio Janeiro Brasilia” [Circa Rio de Janeiro in collibus], [ December 1818 ], J.B.E. Pohl s.n. ( lectotype PRC !, isolectotype W!). = Cheilanthes aquilinaris Fée (1873: 37 , t. 91, fig. 1). Hypolepis aquilinaris (Fée) Christ (1901: 636) . Lectotype (designated by Schwartsburd et al. 2014: 110 ):— BRAZIL . Rio de Janeiro : “Brasilia fluminensis”, [Haut Itatiaia], [ 6 June 1871 ], A.F.A. Glaziou 5330 ( lectotype B!-200074529, isolectotypes C n.v., HBG n.v., K!-000640338, NY-fragment [00144358, image!], P-00633378 [ex Herb. Fée, image!], P-00633379 [image!], P-00633380 [ex Herb. Glaziou, image!], P-00633381 [ex Herb. Glaziou, image!], S-05- 9822 [image!], S-10-34455 [image!], US-00066403 [image!]). Plants forming extensive thickets. Rhizomes long-creeping. Fronds to 3(–4.5) m long; petioles proximally with epipetiolar roots; laminae proximally 3–4-pinnate-pinnatifid; pinnae and pinnules distally with free lobes between the segments; compound distal segments inequilateral, irregularly dissected, caudate at apex; simple distal segments linear, to 3(–4) cm long; costae abaxially with reddish catenate hairs, 5–7-celled, 0.3–0.5 mm long, adaxially glabrous; costules abaxially with reddish catenate hairs, adaxially glabrous; veins abaxially sericeous, with lax, arachnoid hairs, 0.6–0.8 mm long, adaxially glabrous; laminar tissue between the veins abaxially glabrous and totally visible, without farinaceous appearance, adaxially glabrous; laminar margins regularly transformed into pseudo-indusia; pseudo-indusia glabrous. Distribution and ecology: — Colombia , Venezuela , Guyana , French Guiana, Peru , Bolivia , Paraguay , Brazil , Uruguay , and Argentina ; possibly also in Suriname , Central America and Mexico ; from sea level to 2200 m ( Figs. 2 , 6 , 7 ). Additional specimens examined (see also Schwartsburd et al. 2014 for additional specimens from eastern South America):— COLOMBIA . Cesár : Sierra de Perijá , Manaure , 1585 m , 31 January 1945 , M . L . Grant 10719 (US). Magdalena : Mount Auyantepui , 1200–1800 m , 21 May 1937 , F . Cardona 62 ( US ).— VENEZUELA . Distrito Capital : South slope of Cerro Avila , 27 December 1939 , C . Vogl 59 ( LIL ).— GUYANA . Takutu Superior : Kanuku Mountains , 975 m , 22 April 1938 , A . C . Smith 3657 ( NY n.v., US).— FRENCH GUIANA . St. Laurent du Maroni : Massif Dékou-Dékou 4, 4°42’N , 53°57’W , 480 m , 24 November 2000 , J . J . de Granville et al. 14388 ( CAY n.v., P n.v., US).— PERU . Locality unknown [Yamatiliá?], November 1920 , C . Bues 1356 (US) ; Locality unknown [ Yamapaca ], 1700 m , November 1932 , C . Bues 1999 (US).— BOLIVIA . Beni: Ballivian Province , 25 km from Yucumo , 15°17’S , 67°04’W , 950 m , 16 July 1990 , A . Fay & L . Fay 2723 ( MO n.v., US). La Paz : Charopampa , 1901–1902, R . S . Williams 1183 ( US ) ; Nord Yungas , Polo-Polo bei Coroico , 1100 m , October–November 1912 , O . Buchtien 3542 ( US ) ; Nord Yungas , Millunguaya , 1300 m , December 1917 , O . Buchtien , Herb. Boliv. 796 ( US ) ; Sud Yungas , 2100 m , 3 December 1906 , O . Buchtien 455 ( US ). Santa Cruz : Florida , 18°14’23”S , 63°40’40”W , 1520 m , 18 January 2006 , M . Nee & J . Wen 53833 ( US ) ; San Carlos Mapin , 750 m , October 1907 , O . Buchtien 1133 (US). Province unknown: Without locality, 1851, Weddell s.n. ( US ).— BRAZIL . Bahia : Chapada Diamantina , 11°35’28”S , 41°12’27”W , 15 March 2008 , M . L . Guedes et al. 14217 (US) ; Santa Cruz de Cabrália , 16°23’S , 39°08’W , 80–100 m , 5 July 1979 , S . A . Mori et al. 12105 ( US ). Ceará : Near Guaramiranga, 680 m , 22 August 1944 , H . C . Cutler 8241 ( US ). Distrito Federal : Chapada da Contagem , 700–1000 m , 19 August 1964 , H . S . Irwin & T . R . Soderstrom 5301 (US-on 2 sheets). Espírito Santo : Linhares , Comboios , 19 September 1991 , L . Behar & G . M . F . Viégas 354 ( VIES ) ; Marechal Floriano , 20.4131°S , 40.6831°W , 700 m , 12 August 1988 , O . J . Pereira & L . Behar 1629 ( VIES ) ; Santa Maria de Jetibá , 20°08’S , 40°49’W , 6 September 2008 , T . S . Lorencini et al. 49 ( VIES ) ; Santa Teresa , 17 May 1985 , W . Boone 452 ( MBML ). Goiás : Chapada dos Veadeiros , 14°S , 47°W , 1000 m , 14 February 1966 , H . S . Irwin et al. 12817 (US-on 2 sheets) ; Goiânia , entre Goiânia e Nerópolis , 4 July 1968 , J . A . Rizzo et al. 1671 ( UFG ) ; Serra dos Pirineus, 1230 m, 16 May 1973 , W . R . Anderson 10386 ( US ) ; Cocalzinho , Serra dos Pirineus , 17°47’56”S , 48°49’07”W , 1150 m , 18 August 2007 , P . G . Delprete et al. 10293 ( RB ). Mato Grosso do Sul : Ponta Porã, Fazenda Curupi, 20 November 1999 , I . A . Carneiro 1 ( SP ). Minas Gerais : Fazenda São José, 12 September 1963 , R . R . Santos 28653 ( LP ). Paraná : Ponta Grossa , 25°08’27”S , 50°01’46”W , 1000 m , J . Prado & R . Y . Hirai 2351 ( SP ) ; Tijucas do Sul , 14 February 1978 , A . Krapovickas & C . L . Cristobal 33652 ( LP ). Rio de Janeiro : Cachoeira de Macacu , Boa Vista , Santa Fé , 22°27’S , 42°37’W , 4 July 2014 , P . B . Schwartsburd et al. 3323 ( VIC ). Rio Grande do Norte : São Bento, 6°25’28”S , 35°41’57”W , 24 August 2012 , J . G . Jardim et al. 6383 ( RB ). Rio Grande do Sul : Caxias do Sul, 5 March 1949 , Afonso s.n. ( LP ). Roraima : Serra dos Surucucus , 2°42– 47’ N , 63° 33–36’ W , 18 February 1969 , G . T . Prance et al. 10059 ( A n.v., K n.v., INPA n.v. , MG n.v., NY n.v., R n.v., S n.v., US-on 2 sheets). Santa Catarina : Florianópolis, Morro da Cruz, 30 July 2000 , 120 m, D. B . Falkenberg 2000 ( SP ) ; Monte Castelo , Lajeadinho , 23 February 2006 , G . E . Barboza 1610 ( CORD ). São Paulo : Pindamonhangaba , Pico do Itapeva , 22°46’S , 45°32’W , alt. 1888 m , J . Prado & R . Y . Hirai 2337 ( SP , US).— PARAGUAY . Caaguazú : Est. Itá Carú , 29 December 1972 , A . Schinini 5826 ( MO ). Caazapá : Tavai , 26º10’S , 55º17’W , 21 December 1988 , N . Soria 3020 ( MO ). Cordillera : Cerro Ybitú Silla , 1 km S of Tobatí , 25º 12’ S , 57º 07’ W , 28 May 1988 , E . Zardini 4398 ( MO ) . Paraguarí: National Park Ibicu’í, Road to Cesar Barrientos, 26º03’ S , 56º 50’W , 15 September 1988 , E . Zardini 7237 ( MO ).— URUGUAY . Maldonado: Pan de Azucar , March 1947 , A . Lombardo s.n. ( LIL ). San José: Sierra de Mahona , 18 October 1941 , Rosengurtt B-3521 (US). Tacuarembó: Gruta de los cuervos, 31°37’19.1”S , 56°02’34.7”W , 194 m , 28 February 2012 , E . L . Meza Torres et al. 1447 ( RB ).— ARGENTINA . Buenos Aires : General Pueyrredón, Sierra La Peregrina , 13 December 1982 , Alo & Mon 842 ( BAL ) ; Cerro Copelina, 29 January 1932 , C . M . Hicken 512 ( SI ) . Catamarca: El Rodeo, 1500 m , 25 November 1910 , Castillón s.n. (US-1113401); El Rodeo , 27 May 1910 , Castillón s.n. (US-2084229). Córdoba : Depto. Calamuchita , Sierra Grande, Cerro Blanco , 26 August 1952 , A . T . Hunziker 9472 ( CORD ) ; San Alberto , Sierra Grande, Mina Clavero , s.d., Burkart 7757 ( SI ) ; Depto. San Javier , Los Molles , 3 September 2005 , R . E . Morero 120 ( CORD ) ; Sierra de Achala , 15 September 1889 , F . Kurtz 6538 ( SI ). Corrientes : Mburucuyá , 25 June 1952 T . M . Petersen 1761 (US-on 2 sheets) ; Berón de Astrada , January 1977 , A . Schinini 14126 ( LP ). Dept. General San Martín , Tres Cerros , 8 November 1936 , A . Burkart 8030 ( SI ) ; Dept. San Miguel , 12 km NE of San Miguel , Ea. Curuzú Laurel , 27 April 1975 , A . Schinini et al. 11441 ( MO , SI ). Jujuy : Termas de Reyes , cerros, 17 March 1940 , A . Burkart & N . S . Troncoso 11235 ( SI ) ; Depto. Manuel Belgrano , Sierra de Zapala , 14 November 2002 , F . O . Zuloaga et al.7614 ( SI ). Misiones : Dept. Candelaria , Santa Ana , 19 September 1912 , Rodriguez 627 ( SI ) ; Dept. General Manuel Belgrano , 8 km from Bernardo de Irigoyen , 22 May 1991 , Delucchi 519 (LP-on 2 sheets) ; Dept. Guaraní , Predio Guaraní , 15 October 1997 , S . G . Tressens 5934 ( SI ) ; Dept. Iguazú , Puerto Wanda , 16 December 1950 , J . E . Montes 10410 ( LP ) ; Dep. San Ignacio , Teyucuaré , 15 July 1945 , A . Krapovickas 2421 ( LP ) ; Dept. San Pedro ,borde de Ruta Provincial 14, 21 February 2016 , A . Yañez & G . Marquez 167 ( LP ) ; Piñalito Provincial Park , 17 February 2016 , A . Yañez & G . Marquez 142 ( LP ). Salta : Camino a Jujuy , Caldera , 1 February 1949 , A . L . Babrera & H . Schwabe 223 ( US ). Tucumán : Famaillá , La Fronterita , 500 m , 19 February 1922 , S . Venturi 1721 ( US ) . Notes:— Pteridium esculentum subsp. arachnoideum var. arachnoideum is the most common morphotype in eastern and southern South America, but also reaches other regions ( Figs. 2 , 6 , 7 ). It is characterized by free lobes between the ultimate segments, inequilateral, irregularly dissected compound distal segments, which are caudate at apex, simple distal segments to 3(–4) cm long, lax, arachnoid hairs abaxially on veins, giving a sericeous appearance, and laminar tissue between the veins abaxially glabrous, without farinaceous appearance (gnarled hairs absent) ( Figs. 1D–F ). 1b. Pteridium esculentum (G.Forst.) Cockayne subsp. arachnoideum (Kaulf.) Thomson var. paedomorficum Schwartsb. & J.Prado , nom. nov. ( Figs. 5A–E , 6 ) Pteridium aquilinum (L.) Kuhn var. umbrosum Christ ex Rosenstock (1907: 90) [as Pteridium aquilinum var. umbrosa ], nom. illeg. (non Luerssen 1889: 107 ). Lectotype (designated here).— BRAZIL . Rio Grande do Sul : Rio Pardo, Fazenda Soledade, 1906, L.C. Jürgens & A. Stier 118 (NY!, probable isolectotypes MVM! [“ Jürgens & Stier 190 b ”], SI! [“ Jürgens 267 ”], US ! [“ Jürgens 267 ”]). Plants sparse, not forming thickets. Rhizomes short-creeping. Fronds to 1.5 m long; petioles proximally with epipetiolar roots; laminae proximally 3-pinnate-pinnatifid; pinnae and pinnules distally occasionally with free lobes between the segments, generally with only a few decurrent lobes; compound distal segments equilateral, regularly dissected, not caudate at apex; simple distal segments triangular elongate, to 1.5 cm long; costae abaxially with reddish catenate hairs, 5–7-celled, 0.3–0.5 mm long, or sometimes glabrous, adaxially glabrous; costules abaxially with reddish catenate hairs, or sometimes glabrous, adaxially glabrous; veins abaxially with setose to arachnoid hairs, 0.3–0.6 mm long, adaxially with a few setose hairs or glabrescent; laminar tissue between the veins abaxially glabrous and totally visible, without farinaceous appearance, adaxially glabrous; laminar margins irregularly transformed into pseudo-indusia, copiously ciliate; pseudo-indusia interrupted, copiously ciliate. Distribution and ecology: —Possibly the same as Pteridium esculentum subsp. arachnoideum var. arachnoideum , with definitive records from Brazil , Bolivia , Paraguay , Uruguay , and Argentina ( Fig. 6 ). Etymology:— The varietal epithet is an allusion to the pedomorphic nature of this taxon. Specimens examined:— BOLIVIA . La Paz: Charopampa , Mapini , 570 m , November 1907 , O . Buchtien 1135 (US).— BRAZIL . Minas Gerais : Alto Caparaó , P . N . Caparaó , 29/IV/1989 , A . Salino et al. s.n. (UEC-57698) ; Bandeira , Mata do Boi Rajado , 15°48’18”S , 40°30’58”W , 662 m , 1 March 2004 , A . Salino et al. 9406 ( BHCB ) ; Caldas , 5 September 1873 , H . Mosén , ex Herb. Bras. Regnell. 2065 ( BM , K , LE ) ; Conceição do Mato Dentro , 19°06’03.1”S , 43°34’26.9”W , 1250 m , 13 September 2003 , A . Salino et al. 8938 ( BHCB ) ; Diamantina, Trinta-Réis , 13 March 1989 , R . F . Novelino 631 (BHCB- n.v., CESJ , SPF ) ; Moeda , Serra da Moeda , 5 October 1985 , M . J . Chagas & T . S . M . Grandi 6614 ( UEC ) ; Moeda , Serra da Moeda , 20°19’22”S , 43°56’30”W , 1277 m , 7 September 2006 , G . Heringer 91 ( BHCB ) ; Ouro Preto , P . E . Itacolomi , 13 May 1998 , A . Salino et al. 4240 ( BHCB ) ; Rio Acima , RPPN Andaime , 18 February 2004 , J . B . Figueiredo & J . C . Queiroz 254 ( BHCB ) ; Santa Maria do Salto , Distrito Talismã , 16°24’16.5”S , 40°03’27.4”W , 750–850 m , 10 October 2003 , A . Salino et al. 9238 ( BHCB ) ; São Thomé das Letras , Camping do Noel , 7 June 2009 , P . B . Schwartsburd et al. 1997 ( SP ) ; Uberlândia , Estação Ecológica do Panga (bark spore bank experiment), 12 July 1997 , M . A . Ranal 776 ( HUFU n.v. , SP ) ; id., 12 July 1999 , M . A . Ranal 654 ( SP ) ; id., 31 July 1999 , M . A . Ranal 793 ( SP ) ; id., 28 November 1999 , M . A . Ranal 991 ( SP ). Paraná : Bateias , 20 April 2005 , P . B . Schwartsburd et al. s.n. (UPCB-54124) ; Bateias , Alto da Serra , 24 April 2005 , P . B . Schwartsburd et al. 763 ( MBM ) ; Campina Grande do Sul , Morro Capivari Grande , 1400 m , 4 March 2007 , P . B . Schwartsburd & A . M . X. Lima 1247 ( SP ) ; Guaporema , 21 July 1988 , M . V . K . Endo s.n. (MBM-124178) ; Indianópolis , 21 July 1988 , M . V . K . Endo s.n. (MBM-124179) ; Nova Olímpia , 23 April 1988 , J . C . S . Pereira s.n. (MBM-124174) ; Piraquara , Pinhais , 1 March 1970 , G . Hatschbach 23987 ( MBM ) ; Planalto , 17 August 1988 , J . J . Vituri s.n. (MBM-133358 p.p. ) ; Quatro Barras , Graciosa , 27 January 1988 , M . C . Antunes s.n. (MBM-124182) ; Rondon , Indianópolis , 25 February 1988 , M . V . K . Endo s.n. (MBM-124191) ; Santo Antônio do Sudoeste , Cerro Negro , 31 August 1988 , C . Alberto Bonezzi s.n. (MBM-133366) ; São Jorge D’Oeste , 17 August 1988 , M . S . Matzenbacher s.n. (MBM-133368) ; São Mateus do Sul , BR-476, km 152, 26 January 1985 , A . Krapovickas & C . L . Cristobal 39667 ( LP ) ; São Miguel , Dois Vizinhos , 7 January 1988 , M . A . Mascarenhas s.n. (MBM-124183). Rio de Janeiro : Cachoeira de Macacu , Boa Vista , Santa Fé , 22°27’S , 42°37’W , 4 July 2014 , P . B . Schwartsburd et al. 3328 ( VIC ) ; Itatiaia , P . N . Itatiaia , estr. p/ Abrigo Rebouças , km 12, 04 November 1965 , R . M . Tryon & A . F . Tryon 6734 (HB-on 2 sheets) ; Locality unknown, ded. 1838, Anonymous [unreadable] s.n. ( B ). Rio Grande do Sul : Santa Cruz , Fazenda Tangerina , s.d., L . C . Jürgens & A . Stier 95 ( S ?- n.v. [ Syntype of P. aquilinum var. umbrosum ). Santa Catarina : Hammonia , October 1911 , H . Luederwaldt s.n. (NY-00815815, image!, SP-21261) ; Hammonia , October 1911 , H . Luederwaldt s.n. (NY-00815816, image!). São Paulo : São Paulo , Ipiranga , August 1907 , H . Luederwaldt s.n . (SP-21265) ; Municipality unknown (probably near Santo André ), Estação Alto da Serra , June 1910 , H . Luederwaldt s.n. (SP-21266 [on 2 sheets]) ; Municipality unknown, s.d., Anonymous [unreadable] s.n., Rosenstock Filic. Austro- Bras. s.n. ( US ). State unknown: Locality unknown, s.d., W . J . Burchell 1076 ( B , K , LE ) ; Locality unknown, s.d., W . J . Burchell 1401 ( B , K ) ; Locality unknown, 11 September 1948 , A . Macedo 1218- A ( BM ).— PARAGUAY . Caaguanzú : 22 km S de Caanguazú , Estrada Itá-Carú , 29 December 1972 , A . Schinini 5826 ( MBM ). Paraguarí : Parque Nacional Ybycuí , 26º03’S , 56º60’W , 23 June 1988 , E . Zardini 4942 ( MO ) ; Dep. Misiones , Isla San Pablo , 6 April 1988 , S . Keel V-64 ( LP ).— URUGUAY . Artigas: Catalan, November 1927 , Herter 82683 ( SI ). ARGENTINA . Buenos Aires : Mar del Plata , 6 January 1933 , C . M . Hicken s.n. (SI-07232). Chaco : Puente Río Canghí Chico , 28 January 1952 , Meyer 17228 ( MO ) ; Fontana , March 1928 , T . Meyer 39 ( SI ). Cordoba : Camino a Villa Benegas , 29 November 2016 , Gutierrez et al. 1133 ( BA ) ; Depto. San Javier, San Javier, s.d., Castellanos s.n. (BA-10089); Los Molles , s.d., Castellano s.n. (BA-10066 p.p. ). Corrientes : Dept. Mburucuyá , Estancia Santa Teresa , s.d., T . M . Petersen 1761 ( LP ) ; Dept. San Martín , Tres Cerros , Cerro de Susini , 16 September 1979 , A . Schinini et al. 18552 ( LP ). Misiones : Dept. Cainguás , Puerto Rico , 16 May 1949 , J . E . Montes 3892 ( LP ) ; Colonia 2 de Mayo , 22 May 1951 , A . L . Cabrera et al. 335 ( LP ) ; Dept. Iguazú , 20 July 1918 , G . T . Bertoni 1019 ( SI ) ; Dept. Montecarlo , Puerto Piray , Alto Paraná , 21 October 1901 , T . Stuckert 11509 ( CORD ) ; Dept. San Ignacio , Teyú Cuaré , 11 July 1937 , Pérez Moreau s.n. ( BA ) ; San Pedro , Esmeralda Provincial Park , 2016, A . Yañez & G . Marquez 143 ( LP ). Tucumán : Famaillá , La Fronterita , November 1922 , S . Venturi 1721 ( BA ) ; Valle de Tafí , December 1911 , L . Castillón 48 ( SI ) . Notes :— Pteridium esculentum subsp. arachnoideum var. paedomorficum is a fully fertile, pedomorphic form of P. esculentum subsp. arachnoideum , occurring in the same areas of P. esculentum subsp. arachnoideum var. arachnoideum ( Fig. 6 ), and sometimes side by side ( e.g., Schwartsburd 3323 and 3328 ; Gutierrez 1133a and 1133b ). It clearly resembles young plants of P. esculentum subsp. arachnoideum , which have heteroblastic fronds (copiously setosepilose), and yet it is fully fertile with well-developed spores. Ranal (2004) made experiments of germinating spores from tree barks, and the Pteridium specimens she grew resulted in such forms: for example Ranal 776, which was cited by Arantes et al. (2008) as “ Pteridium arachnoideum ”. We hypothesize that pedomorphy in Pteridium may be triggered by self-crosses of gametophytes. This morphotype has long been reported in literature, for example by Rosenstock (1907) and Sehnem (1972) , as “ Pteridium aquilinum var. umbrosum Christ ex Rosenst. ”, an illegitimate name due to an earlier Pteridium aquilinum var. umbrosum Luerssen (1889: 107) . Rosenstock’s description and types formed the base for this variety, which we here validate. These specimens are very common in southern Brazil , and similar specimens were also found in Mesoamerica (see Moran 1995: 162 ). 2. Pteridium esculentum (G.Forst.) Cockayne subsp. campestre (Schrad.) Schwartsb. & J.Prado, comb. nov. et stat.