A New Species of Dioscorea from Costa Rica Barry E. HammelMissouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166 U.S.A.AISTRACT. Dioscorea natalia (Dioscoreaceae) isdescribed from wet to very wet areas on both Pacificand Caribbean slopes of Costa Rica, from the Mon-teverde area to Tapantf National Park. The species'confusion with the related D. lepida C. V. Mortonis discussed, and a key is provided to distinguishit from that species and the other two closely re-lated Costa Rican species, D. racemosa (Klotzsch)Uline and D. standlyei C. V. Morton. During the course of work on a treatment of Dios-corea for the Manual de Plantas de Costa Rica,material of three possible new species was set asidefor further study. Careful examination and reviewdemonstrated that one of them would not be sepa-rated from the recently described Panamanian D.davidsei 0. T6llez, and that the other correspondsto D. lepida. The third, here described as D. na-talia, had previously been identified as D. lepidaand with that species, is closely related to two otherCosta Rican species, D. racemosa and D. standleyi.Dioseorea natalia Hammel, sp. nov. TYPE: Costa Rica. Cartago: Parque Nacional Tapantf, Sen-dero Oropendula, 1400 m, 26 Sep. 1997 (starm. & pist. fl, fr), B. Hammel & S. Troyo 21068 (holotype, INB; isotypes, CR, F, MEXU, MO). Figure 1. Species subtilis D. racemosae affinis. a qua imprimisdiffert inflorescentiis brevioribus, paucior-floribus rachi-dibus exiliorihus. Stems delicate, twisting to the right but also veryrarely to the left. Leaves alternate, ovate to narrowlytriangular-cordate, 4.5-6(-9.5) X 2.5-3.5(-5) cm,7(9)-nerved, glabrous, very faintly glandular-dottedon the lower surface. Staminate inflorescences 4-8(-10) cm, simple racemes to racemose, usually 1to rarely as many as 5 per axil; the rachis � ver-ruculose, very delicate, up to only twice the di-ameter of the pedicels; the cymes of 1 (rarely 2)flowers, subtended by a pair of narrowly triangularbracts 1-1.5 mm; pedicels 1.5-2(-4) mm. Stami-nate flowers with tepals appearing nearly valvate inbud, broadly triangular, 0.8-1.1 mm, patent, paleyellowish green or cream; stamens 3, connivent inthe center of a + hexagonal torus; filaments ca.NOvoN 10: 378-381. 2000.0.1-0.15 mm, united only at the very base; anthercells � ovoid, ca. 0.15-0.2 mm, touching those ofadjacent anthers, dehiscing upward; staminodianone. Pistillate inflorescences 5-8 cm, spikes. Pis-tillate flowers with tepals as in the staminate onesbut to 1.25 mm; styles 3, united in a conical stylarcolumn 0-0.25 mm, the free portion, including stig-mas, ca. 0.4 mm; stigmas 3, simple; staminodialacking. Fruits perpendicular to the rachis, elliptic,1.2-2.0 X 0.5-0.9 cm, apically acute; seeds 1-1.4X 0.3-0.4 cm, winged on the posterior end. Paratypes. COSTA RICA. Alajuela: Reserva ForestalSan Ram6n, 11(X) n, Apr. 1991 (fl), Bitner 972 (CR);between San Miguel and La Palma de San Ram6n. Nov.1926, Brenes (278) 5124 (CR); Monteverde Reserve. RfoPefias Blancas, 900 m, Aug. 1988 (fl). Bello 248 (CR).Guanacaste: Monteverde, 1 km al N de Ias Nubes, 13(X)nm Sep. 1988 (stam., pist. fl, fr), Haber & Zuchowski 8675(INB, MO); road to Las Nubes, 1400 m. Nov. 1988 (slam.,pist. fl), Haber 8749 (INB). Puntarenas: Monteverde Re-serve, I km SW of Station, 15(X) n, Feb. 1992 (fl), Ingram& Ferrell 1298 (CR); Monteverde vicinity. Upper Rfo Ne-gro valley, 15() m, Sep. 1985 (fl, fr), Haber ex Hello 3020(CR); Monteverde vicinity. San Gerardo Biological Station,12(0) n, Feb. 1995 (pist. fl, fr), Penneys 167 (CR, F, INB,MO, US). San Jose: Rfo Hondura, 11(X) m, Feb. 1974(fl), Ient 3791 (CR). Cartago: Cafi6n del Rfo (rande deOrosf, Oct. 1983 (fl. fr), Chac6n et al. 1483 (CR-6mounted duplicates); Parque (Refugio) Nacional Tapantf,1250 n, Aug. 1991 (stam. fl), Hammel et al. 18324 (INB.MO); 14(X) m. Dec. 1992 (fl), Herrera 5813 (CR), June1994 (stam. fl), Morales & Carnevali 2873 (INB); Valledel Reventaz6n, Moravia de Chirrip6, 1 1() m. Sep. 1993(stain. fl), Campos & Campos 186 (INB). Distribution. This species, apparently endemicto Costa Rica, is known from some of the very wet-test parts of the country, especially P. N. Tapantf.However, it is also known from the Las Nubes areaof Monteverde, which is relatively dry. So far it isknown only from 900-1500 m, from Monteverdeand Tapantf, and several intervening localities. Etymology. It was my pleasure to defer to Sil-via Troyo, illustrator of this new species, the honorof choosing its name. When she came across thespecies for the first time in the field, she was struckby the same joy of discovery as any taxonomistupon finding such a new species, so tiny and pre-cious. For all good reason, she chose the name Na-talia, one often given here to first-horn daughters,and that of her own. The epithet "natalia" is used
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