MARCH 1990 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 57: 169-172 Chigua, A New Genus in the Zamiaceae with Comments on Its Biogeographic Significance Abstract STEVENSON, D. W. (New York Botanical Garden, Bronx, New York 10458, USA). Chigua, a new genus in the Zamiaceae with comments on its biogeographic significance. Memoirs of the New York Botanical Garden 57: 169-172. 1990.-Chigua a new genus in the Za- miaceae from Colombia is described and illustrated. This genus differs from all other cycad genera in having a prominent midrib with longitudinally dichotomous branched lateral veins in its pinnae and hexagonal sporophylls with raised mounds on the peltate face at the angles. Two species are described and illustrated: C. restrepoi sp. nov. and C. bernalii sp. nov. which differ from each other chiefly in leaflet width, length, and shape. The main biogeo- graphic significance lies in this genus being the only endemic genus in the Cycadales for South America. Key words: Chigua; Zamiaceae; South American endemic. Introduction shaped leaflets that were also more numerous per leaf, narrower, and longer. It was also clear that In 19 18, Francis Pennell collected a single this material represented a new genus in that specimen of a cycad tentatively assigned to Za- both the leaflets and the sporophylls were quite mia. This specimen, which consists of part of an unlike those known for any of the currently known unbranched subterranean caudex and a single leaf, cycad genera. is unusual in that the leaflets have a prominent The genera of cycads are easily separable on midrib with lateral veins running longitudinally leaf, leaflet, and sporophyll characters. Thus, for and branching dichotomously. Because this was example, Dioon Lindl. has leaflets that are lat- a unicate, Sergio Sabato and I thought that per- erally decurrent on the rachis and has flat spo- haps the specimen represented a teratism as we rophylls with the megasporophylls having two had never seen any other cycad specimens with stalked ovules, whereas, in contrast, Ceratoza- this leaflet character. Knut Norstog and I recently mia Brongn. has articulated leaflets and peltate travelled to Colombia in search of more material sporophylls with two horns and sessile ovules. A that would conform to Pennell's collection. For- comparison of any other genera would reveal just tunately, the trip proved successful and more as significant differences. Because the cycad gen- material was collected (along with strobili) that era are so distinct from one another in both re- was the same as that collected by Pennell and, productive and vegetative characters, any new moreover, some 50 km distant a second collec- genus should also be unique in these characters. tion was made of plants with quite differently Below is a description of such a new genus and its two species along with a comparison of it to long, 1-2 cm wide, stipulate; leaves 2-3, gla- other genera that have some similarity in general brous, stipulate; petiole subterete, 60-80 cm long, in leaflet characters. armed with prickles; rachis semiterete, 60-100 cm long, armed with prickles below, smooth Chigua D. Stevenson, gen. nov. above; leaflets alternate below, subopposite in Foliola subopposita vel alternata, con medio middle, opposite above, 20-30 on each side, lan- nervis praedita, laterale longitudinale e dicho- ceolate, 3-5 cm wide, 15-25 cm long, papyra- tomi; sporophyllus ? peltatus, hexagonus, ad ceous, sessile, cuneate at base, caudate at apex, quemqua angulum umbunatus; sporophyllus 8 margins with well defined teeth; microsporan- peltatus, hexagonus, planus. giatestrobilus cylindrical, 5 cm long, 2 cm diam., covered with reddish-brown tomentum; pedun- Leaflets subopposite to alternate, prominent cle glabrous, 10 cm long, 1 cm diam.; micro- midvein present, lateral veins longitudinal and sporophylls peltate, sterile peltate tip flat; mega- dichotomously branched; megasporangiate stro- sporangiate strobilus cylindrical, 15 cm long, 5 bili with hexagonal peltate sporophylls; mega- cm diam., covered with reddish-brown tomen- sporophylls with a conspicuous bump at each tum; peduncleglabrous, 30 cm long, 1.5 cm diam.; angle of the hexagon; microsporangiate strobili megasporophylls peltate with a narrow basal stalk, with hexagonal peltate sporophylls. hexagonal with a conspicuous bump at each an- Type Species: Chigua restrepoi D. Stevenson. gle of the hexagon; seeds ovoid, red at maturity. The genus name is derived from the Spanish Paratypes. COLUMBIA. Primary rainforest, transliteration of an Indian common name for 120 m, 24 Jul 1986, R. Bernal, G. Galeano & D. cycads in Central and South America. Restrepo 1138 (COL, FTG); 28 Sep 1986, I. Chigua restrepoi D. Stevenson. Type1. COLUM- Turner 3 (FTG); 90-1 20 m, 5-6 Mar 19 18, F. BIA. Primary rain forest, elev. 150 m, 14 Mar Pennell 4608 (NY). 1987, D. Stevenson 693 (holotype: HUA, iso- This species is named in honor of the late Padre types: FTG, NY). Fig. 1A-H. Sergio Restrepo, an excellent local botanist who located the species. Truncus hypogaeus, humilis, elipsoidus, 15 cm diam., 40 cm longus; cataphyllus lanata, trian- Chigua bernalii D. Stevenson. Type. COLUM- gularis, stipulis; folia pauca, 2-3, glabra; petiolus BIA. Primary rain forest, 150 m, 27 Jul 1986, subteres terves, 60-80 cm longus, validus spinus R. Bernal. G. Galeano & D. Restrepo 1189 armatus; rachis semiteres, 60-100 cm longus, in (holotype: COL; isotype: FTG). Fig. I. dimidio inferiore pucis spinis armata, supra iner- mis; foliola inferiore alternata, medio suboppo- Truncus hypogaeus, humilis, ellipsoidus, 10 sita, supra opposita, 20-30 juga, lanceolata, 3-5 cm diam., 30 cm longus; cataphyllus lanata, cm lata, 15-25 cm longa, basi cuneata, apicem triangularis, stipulis; folia pauca, 2-3, glabra, sti- pulis; petiolus subteres terves, 1-1.4 m longus, caudata, margine dentata; strobilus 8 cylindri- cus, vel 5 cm longus, 2 cm latus, ferrugineo-to- validus spinus armatus; rachis semiteres, 60-1 60 mentosus; microsporophylla peltata, hexagona, cm longus, in dimidio inferiore pucis spinis ar- mata, supra inermis; foliola inferiore alternata, plana; strobilus P cylindricus, vel 15 cm longus, 5 cm latus, ferrugineo-tomentosus; megasporo- medio subopposita, supra opposita, 30-55 juga, phylla peltata, hexagona, ad quemqua angula lineara vel linear-lanceolata, 1-1.5 cm lata, 30- umbunata, ovulo duo; semina ovidea, rubra. 35 cm longa, basi cuneata, apicem longa caudata, margine dentata e undulata. Stem hypogeous, ellipsoid, 15 cm diam., 40 cm long; cataphylls pubescent, triangular, 3-5 cm Stem hypogeous, ellipsoid, 10 cm diam., 30 cm long; cataphylls pubescent, triangular, 3-5 cm long, 1-2 cm wide, stipulate; leaves 2-3, gla- As in previous papers, I have purposely omitted brous, stipulate; petiole subterete, 1-1.4 m long, precise locality data in an attempt to prevent eradi- armed with prickles; rachis semiterete, 60-160 cation by commercial collectors. Only a very few plants of this genus have been seen in the wild, and I am cm long, armed with prickles below, smooth convinced that commercial collectors would, either in- above; leaflets alternate below, subopposite in tentionally or unintentionally, cause its extinction. middle, opposite above, 30-55 on each side, lin- STEVENSON: CHIGUA, A NEW CYCAD GENUS Fig. 1. Chigua. A-H. Chigua restrepoi. A. Megasporangiate strobilus. B. Peduncle. C. Abaxial view of megsporophyll. D. Adaxial view of megasporophyll. E. Leaf base with stipules. F. Cataphyll. G. Leaflet. H. Microsporangiate strobilus. I. Leaflet of C. bernallii. (A-D and H by Priscilla Fawcett, E-G and I by D.W.S.) 172 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN [VOL. 57 ear to linear-lanceolate, 1-1.5 cm wide, 30-35 seedlings of Microcycas A. DC., and the previ- cm long, papyraceous, sessile, cuneate at base, ously mentioned pattern of sugars in its muci- caudate at apex, margins with well defined teeth lage. and undulate. Strobili unknown. In a recent paper on the biogeography of the This species is named for Rodrigo Bernal who neotropical cycads, Balduzzi et al. (1982) dis- first discovered it and in recognition of his ex- cussed the lack of a cycad genus endemic to South cellent work in neotropical cycad research. America. Indeed, we have predicted that an en- The major features that distinguish Chigua demic genus either existed and is extinct or had from other cycad genera are the presence of a yet to be found. When we first studied the Pennell leaflet midrib with longitudinally dichotomizing collection, Sergio Sabato and I realized it rep- lateral veins and the peculiar raised areas that resented a potential candidate for that status. are present at the angles of the hexagonal Without more material, however, and which, megasporophyll face. While the raised areas on more importantly, possessed distinctively differ- the sporophyll face is unknown for any other ent reproductive characters, the question would cycad taxa, the midrib is present in two paleo- remain unresolved. tropical genera, Cycas L. and Stangeria T. Moore, Cycad genera, in general, show an endemic but not in any neotropical genera. distributional pattern, with three genera endemic The presence of the midrib in the leaflets of to Australia: Bowenia Hooker ex Hooker fil., Cycas and Stangeria needs some discussion. First, Lepidozamia Regel, and Macrozamia Miq.; two the total venation pattern of Chigua is quite dif- endemic to Southern Africa: Encephalartos ferent from that in the other two genera. In Cy- Lehm. and Stangeria; one endemic to Cuba: Mi- cas, the midrib is the only vein in the leaflets and crocycas; and two to Northern Central America: it is raised on the abaxial surface with a groove Ceratozamia and Dioon. The exceptions to this appearing above the midrib on the adaxial sur- pattern of endemism are Cycas, which is distrib- face. In Stangeria, the midrib appears raised on uted widely around the Indian Ocean Basin and both surfaces as in Chigua, but the lateral veins in tropical Asia, and Zamia which is widespread depart at a right angle and then dichotomize near in the neotropics.