Podostemum rutifoliumsubsp. ricciiforme (Liebmann) A. Novelo & C. T. Philbrick, comb. nov. Marathrum ricciiforme Liebmann ("Marathrum ricciaeforme"), Forh. Skand. Naturf. Mote 5: 512. 1847. Podostemum ricciiforme (Liebmann) P. Royen, Acta Bot. Need. 3: 240. 1954.-TYPE: MEXICO. Puebla: Huitamalco [Hueytamalco], May 1841, Liebmann s.n. (holotype: C!; isotype: L!).-MEXICO. Oaxaca: Mpio. Santa Maria Chimalapa, El Turnbo, cascada grande del Rio del Corte, 210 m, 24 Apr 1988, Wendt & Hernandez 5896 (epi type: designated by Novelo & Philbrick, 1997b: MEXU!). Roots 0.2-1.0 (0.7) mm wide. Stems arising 0.7-6 (3.5) mm apart along roots, 0.03-37 (1) mm long. Leaves simple to 1-4 (1) times divided; simple leaves 0.7-9.3 (2.6) mm long, 0.3-2.7 (0.7) mm wide, apices rounded or blunt; divided leaves 2.2-13 (5.7) mm long; ultimate leaf divisions 0.4-5.8 (3.1) mm long, 0.3-1 (0.6) mm wide, awl-shaped, triangular or parallel-margined, flattened, with a faint central vein or central vein absent, apices rounded or blunt; petioles 0.2-5 (2) mm long, rounded or elliptical in cross section; leaf bases symmetrical (asymmetrical on lowest leaves of young stems); stipules 0.1--0.6 (0.3) mm long, entire or with 2 flattened triangular teeth, teeth 0.05--0.4 (0.2) mm long. Flowers 1-3 (1; N=50) per stem; spathella 1.6-4 (2.7) mm long, 0.7-1.5 (1) mm wide; tepals 3-4 (rare), apex blunt, often darkened distally; lateral tepals 0.5-1 (0.7) mm long; andropodial tepal 1-2 (1), rarely absent, 0.1-1.1 (0.6) mm long, (flowers in some populations with 0-2 andropodial tepals, 2-4 lateral tepals and 0-1 stamens); andropodium 0.3-1.2 mm (0.9) mm long prior to anthesis, during anthesis 0.6-3.2 (2; N=22) mm; stamens 2; filaments 0.2-0.5 (0.4) mm long prior to anthesis, during anthesis to 0.2-0.7 (0.5; N=8) mm; anthers 0.4-0.9 (0.6; N=17) mm long, 0.4-0 .8 (0.6; N=17) mm wide; pollen dyads 22-32 (28) µm long, 12-20 (18) µm wide; ovary 0.7-2 (1.5; N=24) mm long, 0.6-1.5 (1.1; N=24) mm wide; stigmas 0.3-1.1 (0.6; N=24) mm long prior to anthesis, during anthesis to 0.6-1.4 (1.1; N=33) mm; pedicels 0.4-2.2 (1; N=24) mm long prior to anthesis, during anthesis to 1.8-4.2 (3; N=41) mm. Capsules 1.4-1.9 (1.6; N=36) mm long, 0.8-1.5 (1.1; N=34) mm wide; pedicels in fruit 1.2-3.6 (2.1; N=34) mm long; seeds 0-2 per capsule, seldom pro duced (N=5), 0.2-0.4 mm long, 0.1-0 .2 mm wide.
Distribution. Mexico, Belize, Costa Rica, and Colombia; forming dense growth on rocks, sometimes rare and difficult to find; 140-1220 m.
REPRESENTATIVE SPECIMENS. Mexico. OAXACA: Rio Santiago, San Felipe Usila, Novelo & Calzada 1426, 1430, 1432 (MEXU); Rio San Cristobal, Valle Nacional, Novelo et al. 1443 (MEXU), Novelo & Philbrick 1452 (MEXU); Rio Usila, San Felipe Usila, Novelo & Philbrick 1469 (MEXU); Rio del Corte, Mpio. Santa Maria Chimalapa, El Turnbo, Wendt & Hernandez 5896 (MEXU).- PUEBLA: Barranca de Huitamalco, Liebmann s.n., May 1841 (C, L).- TABASC0 : Rio Pedregal, Mpio. Huimanguillo, en la poblacion Carlos A. Madrazo, Novelo & Ramos 1907, 2060 (MEXU) .- VERACRUZ: Cordoba, Kerber 83 (BM); rio a la entrada del poblado de Coatepec, Novelo et al. 1217 (ME XU); Rio Huehueyapan, rio que atraviesa el poblado de San Marcos, Jico, Novelo et al. 1219 (MEXU), Novelo & Calzada 1225 (MEXU); Rio Puente Nuevo, Coatepec, Novelo & Calzada 1223 (MEXU) ; Rio Huehueyapan, San Marcos, Novelo & Calzada 1412 (MEXU); Rio Huehueyapan, atraviesa el poblado de San Marcos a 20 km al sur de Xalapa, Jico, Novelo & Philbrick 1407 (MEXU).
Belize. TOLEDO: Ek Xux Valley, Davidse 35962 (MO). Costa Rica. Without locality, Endris 181 (K, L).
Colombia. NARIN0: Rio Arrayan, at confluence with Rio Guiza, Hagemann 19081 (WCSU).
Distinctions between P. rutifolium subsp. ricciiforme and subsp. rutifolium are discussed above. Novelo and Philbrick (1997a) inferred that a specimen from Costa Rica (Endris 181) deposited in C may be an undescribed species. We have re-examined that specimen and conclude that it is not a distinct species but rather a large form of P. rutifolium subsp. ricciiforme.
The primary distribution of P. rutifolium subsp. ricciiforme is on the Atlantic slope of Mexico (Novelo & Philbrick 1997b). Historical and/or extant localities are in the Mexican states of Puebla, Tabasco, Veracruz, and Oaxaca. The subspecies has been extirpated from the type locality in Puebla. In Veracruz, it persists in rivers that are polluted from domestic and industrial sources (Quiroz et al. 1997). In Mexico, subsp. ricciiforme occasionally occurs with Marathrum tenue Liebm. The subspecies has also been recently documented from one river in Belize. One historical collection is available from Costa Rica, although the exact locality is not known. Attempts to relocate this taxon in Costa Rica have not been successful (Garrett E. Crow, pers. comm.). One collection of the subspecies is known from the southern region of Colombia. The small size of the plants likely contributes to their being overlooked and undercollected.
Podostemum rutifolium subsp. ricciiforme was first described as a species of Marathrum (Liebmann, 1847; see further discussion in Novelo & Philbrick 1997b). Royen (1954, p. 240) transferred the species to Podostemum. Because of the incomplete nature of the holotype, we selected an epitype (Novelo & Philbrick 1997b). At the time we were unaware of an isotype located in L (also incomplete, as is the holotype), although its presence does not alter our rationale for designating an epitype. We abide by our previous decision (Novelo & Philbrick 1997b).