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1996 A Revision of (Euphorbiaceae) Sheila M. Hayden University of Richmond, [email protected]

W. John Hayden University of Richmond, [email protected]

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Recommended Citation Hayden, Sheila M., and W. John Hayden. "A Revision of Discocarpus (Euphorbiaceae)." Annals of the Missouri Botanical Garden 83, no. 2 (1996): 153-67.

This Article is brought to you for free and open access by the Biology at UR Scholarship Repository. It has been accepted for inclusion in Biology Faculty Publications by an authorized administrator of UR Scholarship Repository. For more information, please contact [email protected]. Volume 83 Annals Number2 of the 1996 Missouri0 0 Botanical Garden

A REVISION OF Sheila M. Hayden and W. John Hayden2 DISCOCARPUS (EUPHORBIACEAE)l

ABSTRACT

As revised here, Discocarpus is interpretedto consist of three neotropical species: D. essequeboensis Klotzsch, D. gentryi S. M. Hayden, which is described and named herein as new to science, and D. spruceanus Mull. Arg. One previously accepted name, D. brasiliensis Klotzsch ex Mull. Arg., is reduced to synonymyof D. essequeboensis. Lecto- types are proposed for the two species previously described. One species is newly excluded fromDiscocarpus, as are three others, followingprevious literature. Foliar anatomy is described with a focus on epidermal sclereids, which are shown to occur on both epidermides. Evidence presented supports close relationships with Lachnostylis Turcz. and Amanoa Aubl.; little was found to support previous hypotheses concerning a relationship with ChonocentrumPierre ex Pax & K. Hoffm.

Discocarpus Klotzsch is a of trees found in namedwas D. spruceanus Mull. Arg.(1863), based seasonally flooded riparian habitats of northern on collectionsof RichardSpruce from the Rio Ne- South America, where they are components of the groof Brazil. Some 32 yearsafter being first men- forest canopy. The are dioecious and bear tionedby Klotzsch, D. brasiliensisMull. Arg. (1873) small clusters of flowersin the axils of simple, al- was formallynamed, based on a collectionof von ternate, entire leaves. Martiusfrom the early 19th century.Three taxa Discocarpus was first described by Klotzsch were added to the genus in the 20th century.The (1841) who initially named, but did not describe, firstaddition was D. hirtus (L. f.) Pax & K. Hoffm. two species; he subsequently described one of (Pax & Hoffmann,1922), a consequence of syn- these, D. essequeboensis Klotzsch (1843), based on onymizingthe South Africangenus Lachnostylis Schomburgk collections fromthe Essequibo River with Discocarpus. In currentliterature, however, region of Guayana. Omitting two nettles (Urtica- Lachnostylis is treatedas distinctfrom Discocarpus ceae) fromMexico and Nicaragua grosslymisplaced (e.g., Levin, 1986; Mennega, 1987; Webster, in the genus, the next species of Discocarpus to be 1994b). The two mostrecently described species,

1 Financialsupport for the master'sthesis research upon whichthis studyis based was generouslyprovided by the GraduateSchool of Arts and Sciences at theUniversity of Richmond. We thankRafael de Sd, Miles F. Johnson,Geoffrey A. Levin,Gary Radice, Dean Simpson,Donna M. E. Ware,and an anonymousreviewer for assistance, and the curators of BM, BR, C, E, F, G, GH, GOET, ILLS, K, L, LD, M, MANCH, MICH, MO, NY, OXF, P, R, RB, RSA, S, TCD, U, UC, URV,US, and W forthe loan of herbariumspecimens. 2 Departmentof Biology,University of Richmond,Richmond, Virginia 23173, U.S.A.

ANN. MISSOURI BOT. GARD. 83: 153-167. 1996. 154 Annals of the MissouriBotanical Garden

D. mazarunensisCroizat (1948) and D. duckeanus Dioecious trees (or shrubs),(3-)10-30 m tall, Jabl. (1967), were based on South Americanma- DBH 25-100 cm. Twigsglabrous to short-pilose, terial. silverygray to dark purplishred; lenticelsraised, Jablonski(1967) accepted the fiveSouth Amer- elongate,parallel with the axis; terminalbuds acu- ican species noted above as distinctentities con- minate,cylindric, glabrous to tomentose,3-7 mm stitutingDiscocarpus, but his treatmentindicated long, oftenwith two basal knoblikeprotrusions, severalgaps in the available data on these plants. sometimessexually dimorphic.Leaves alternate, For example,staminate or pistillateflowers were simple,petiolate, glabrous, leathery; petioles 4-8 undescribedfor several species. Furthermore,re- mm long, wrinkled;margins entire; base obtuse; centstudies reveal that two of the species accepted apex acute to acuminate;venation pinnate; ultimate by Jablonskiwere misplacedin Discocarpus,and veinsreticulate, orthogonal. Stipules fugaceous. In- presentlyavailable collectionsindicate the exis- florescenceaxillary, 1-several flowersper node; tence of a previouslyunrecognized species (Hay- flowerclusters sessile, subtended by cupulate den, 1995). In addition,the issue of genericrela- bracts;bracts ca. 1 mmlong, 1 mmwide, glabrous tionshipsis unresolved.Discocarpus was classified to pubescent;staminate clusters several per node; mostrecently in subfamilyPhyllanthoideae Asch. pistillateclusters one per node. Staminateflowers tribe Wielartdieae Baill. ex Hurus. (Webster, sessile, congested,10-30 per node; sepals (4) 5, 1994b), but earlier concepts of genericrelation- 1.5-2 mmlong, 1-1.5 mmwide, pilose; petals (0- ships have variedwidely (see below).Moreover, re- )5, delicate, hyaline,glabrous to pubescent,less portsof foliar sclereids in Discocarpusand Amanoa than1 mmlong, linear, often fringed apically; disk (Gaucher,1902; Levin,1986) suggestthe newpos- extrastaminal,lobed; stamens(4) 5; filamentsfused sibilityof placement in tribeAmanoeae. This paper belowthe level ofthe disk, free portions 1.5-3 mm providesa revisionof Discocarpus,including de- long; antherselongate, 1 mm long, longitudinally taileddescriptions of foliar anatomy and discussion dehiscent,exserted; pistillode segmented into two of relationships. or threelinear, pubescent, membranous filaments. Pistillateflowers 1-3(-5) per node; pedicels essen- MATERIALS AND METHODS tiallylacking to 5 mmlong; sepals 5, cupulate,1.5- 3 mmlong, 1-2 mmwide, densely pubescent; pet- This revisionis based on a totalof 171 herbar- als (0-)5, hyaline,0.5-3 mm long, up to 1 mm ium specimensof Discocarpusborrowed from 29 wide, pubescent;disk slightly4obed; ovary3-car- herbariain the UnitedStates, Europe, and South pellate, subglobose,smooth or sculpted,densely America.Small samplesof leaf tissuefrom the fol- pubescent;styles 3, partedto thebase or nearlyso, lowing collectionswere removedfor anatomical spreadinghorizontally, densely pubescent below; study: Discocarpusessequeboensis Klotzsch, Jan- stigmas3, dilated, lobed, horizontalor reflexed; goux & Bahia 294 (NY), Krukoff& Froes 11974 ovules 2 per locule. Fruitssymmetrically 3-lobed (NY), Maas et al. 7395 (U), Schomburgk659 (U), or asymmetrically 6-12 mm 6-15 Silva 4776 (NY), Smith2692 (F); Discocarpusgen- subglobose, tall, mmdiam., dehiscentinto or 6 tryiS. M. Hayden,Encarnacion 25065 (F), Vdzquez longitudinally 2, 3, 1 mm & Jaramillo5487 (NY); Discocarpusspruceanus mericarps,1-3-seeded; pericarpca. thick, Mull. Arg.,Davidse 27631 (NY), Wurdack& Ad- hard, brittle;surface smooth to deeply sculpted, derly43349 (NY). Half of each samplewas mount- densely pubescent; columella persistent.Seeds ed directlyon stubsand sputtercoated with a gold/ subglobose,ecarunculate; testa thin, shiny. mixture SEM. palladium priorto observationwith Discocarpus can be distinguishedfrom other The second halfof each samplewas rehydrated by woodygenera of subfamilyPhyllanthoideae by the boilingin waterwith a few drops of Aerosol OT, combinationof: deciduousstipules; dioecy; minute dehydratedin tertiarybutanol, embedded in par- petal-bearingflowers produced in axillaryclusters; affin,and sectionedat 10 on a micro- jkm rotary lobed extrastaminaldisks; finely reticulate exine on tome. Paraffinsections were stained in toluidine pollen grains;and stylesthat are notbifid, but ter- blue (Berlyn& Miksche,1976) or a combination minatein threedilated, irregularly lobed stigmas. of saffraninand haematoxylin(Johansen, 1940). It is noteworthythat floral merosity and presence ofpetals are somewhatinconstant. Most flowers are SYSTEMATIC TREATMENT 5-merous,but 4-merous flowers are notinfrequently Discocarpus Klotzsch,Archiv. Naturg. 7(1): 201. encountered.Most flowers examined showed petals 1841. TYPE: Discocarpus essequeboensis to be presentand isomerouswith the sepals, but Klotzsch.Figures 1-4. sometimesfewer petals, or even none, will be Volume83. Number2 Hayden& Hayden 155 1996 Revisionof Discocarpus

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found. Notably,the minute Size and flimsy-texture ing highlyregular minute areoles that lack free- of the petals render them easy to overlook. Impor- ending veinIet . tant clues to recognizing the genus in sterile con- In Websters(1994bi kev to generaof Wielan- dition include the elongate terminal buds with dieae. twoaspects of morphology of staminateflow%-- paired distinctivebasal knobs and fine veins form- ers attributedto Discocarpu~sare at Variancewith 156 Annalsof the MissouriBotanical Garden

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of oni ltsh Figure crlsDsoapss 5al. Dis.tribution Discocarpus SquareiS.M DHcoaryusessn. theabove description.Staminate flowers are sessile long undulateridges with sharp crests (be- and bear filamentsfused to the base of the pistil- neath dense indumentum);fresh staminate flowersyellow; Amazonian Peru and western lode, featuresalso noted by Pax and Hoffmann Brazil D. gentryiS. M. Hayden (1922). 2b. Pistillateflowers sessile or nearlyso; ovary Three species of Discocarpusoccur in the Ama- and fruitsurface weakly sculpted into mur- zon and OrinocoRiver basins of Brazil,Colombia, icae or shortundulate ridges with rounded Peru, and Venezuela,as well as smallerrivers of crests (beneath dense indumentum);fresh staminateflowers cream; Guyana, Surinam, Guyana and Surinam(Fig. 5). Habitat is lowland and northeasternBrazil rainforestbelow 250 m, along seasonallyflooded ------D.essequeboensis Klotzsch riverbanksof vdrzeaforests or occasionallyinun- dated fields.Discocarpus species can formcanopy Discocarpus essequeboensis Klotzsch,London J. trees, but samples are sometimescollected from Bot. 2: 52. 1843. TYPE: Guyana.On branch specimensdescribed as small shrubs. of upper Essequibo River, Schomburgk 35 (lectotype,selected here, BM; isolectotypes,G, KEY TO SPECIES OF DiscocARPus(FIGS. 6-9) K, OXF, P, U, W). Figures10, 3, 4, 9. la. Terminalbud of staminatespecimens lacking Discocarpusbrasiliensis Klotzsch ex Mull. Arg. Mart.Fl. basal knobs,covered with dense indumentum; Bras. 11(2), 13: 1873. SYNTYPES: Brazil. Bahia: ovaryand fruit surface smooth; fruits 1(-2)-seed- near Villa do Rio de Contas,Martius s.n. (G, L, M, ed, 2 carpelsusually abortive; widely scattered MO); Bahia: Martiuss.n. (M). in theAmazon and OrinocoRiver basins ------D.spruceanus Mull. Arg. Trees,10-20 m tall, DBH 25-100 cm. Terminal lb. Terminalbud of staminatespecimens with two buds similarin staminateand pistillatespecimens, prominentbasal knobs, glabrous or only sparsely glabrous,with two basal knobs. Leaves 8-22 cm pubescent;ovary and fruitsurface sculpted; fruits3-seeded, all carpelsaccrescent. long,4-8 cm wide;apex acuminate(to 10 mmlong) 2a. Pistillateflowers on pedicels4-5 mmlong; to merelyacute. Inflorescencebracts glabrousto ovaryand fruit surface deeply sculpted into pubescent. Staminateflowers 10-30 per node, Volume 83, Number2 Hayden & Hayden 157 1996 Revision of Discocarpus

Figures6-9. Ovaryand fruitsurface features of Discocarpus. -6. Discocarpusgentwi S. M. Hayden.Gentry et al. 18419 (F). Ovary.7 Discocarpusgentryi S. M. Hayden.Reilat 411 (N-Y).Mature fruit. -8. Discocarpusspruceanus Mul. Arg..Spruce 3527 (P). Maturefruit with one developedand twoaborted lobes. -9. Discocarpusessequeboensis Klotzsch.Schomburgk 706 (GO.Mature fruit. All bars = 2 mm.

cream-colored;sepals (4) a. 2 mm long. 1.3 mm fromJune throughDecember. fruits.from Septem- wide;petals (0-)5. pubescent:disk lobed: stamens ber throughDecember. (4) 5; pistillodesegments 3. Pistillateflowers 1-5 per node: pedicel 0-1 mm: sepals 3 mm long. 2 Common Names. --Square Wood (in reference mmwide, light green; petals reduced.(0-)5. 0.5-3 to shape of trunk.Anderson 408): -Oity do Campo mm long; ovaryshallowly municate to reticulate: (Froes & Krukoff 1 974). stigmasreflexed. Immature fruitsdark red: mature Additionalspecimens examined. BRAZIL Amapi: fruitbrown. symmetrically 3-lobed. 8-9 mm tall. Bastos 201 (MO). Amazonas: Martiuss.n. L(: Mau>s. 10-15 mmdiam.. 3-seeded. surfaceweakly sculpt- Pires109 (NY. U). Bahia: Villa do Rio de Contas.Martius ed into shallowmuricae or shortundulate ridges s.n. (G. L M). Goiis: Rio Araguaiaat mouthof Rio Ja- vats. Silha 4862 (ILLS. NY): Rio Piranha. Silta 4;776 withrounded crests. Seed 6-8 mm diam.; micro- (NY). Maranhio: Rio Alto TuriaVu.Nov a Esperana. pylarand basal surfacessomewhat flattened: testa 205'S. 45z3'. Jangoux& Bahia 294 INY. RB): Rio Pin- red-brown. dare Basin. Monvao.Fr6es & Krukoff11974 )GH. MICH. NY. US): Rio Mearim-Lapela.municipality de Vit6riado Distribution.Central and easternBrazil. Guv- mearim.Campo Coberto. SiLfa 4191 (RB. Mato Grosso: ana. Surinam(Fig. 3): on sandy soil in fiequentlv marginof Rio Juruena.Rosa & Santos 2149 (MO. NY-). Para: MarabA.Fr6es & Black 24.336 (P. U): inundatedforest Cachoeira along rivers(vdrzea) and periodi- Porteria.Rio Trombetas.Ducke 8953 iBM.G): Rio Trom- cally floodedfields. Flowers have been collected betas margin.Ducke 7988 (BM): Rio Trombetasmargin. 158 Annals of the MissouriBotanical Garden

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Figure 10. Discocarpusessequeboensis Klotzsch. -A. Disk fromstaminate flower; Pires 109 (U). -B. Staminate flower,one sepal removed;Pires 109 (U). -C. Habit, staminatespecimen; Krukoff 11974 (NY). -D. Habit,pistillate specimen;Rosa & Santos 2149 (MO). -E. Immaturefruit; Schomburgk 35 (W). -F. Terminalbud; Krukoff11974 (NY). Volume 83, Number2 Hayden & Hayden 159 1996 Revision of Discocarpus

Ducke 7993 (BM); Nationalpark of Tapaj6s,60 km from any other consistent character of either pistillate or marginof Rio Tapaj6s, Silva Itaituba-Jacarecangaat the staminate material of D. essequeboensisand D. bras- & Rosdrio3992 (NY). GUYANA.Upper Essequibo River, Schomburgk706 (BM, G, K, L, P, U, W); upperEssequibo iliensis that delineates two separate species, the de- River,Schomburgk 659 (BM, E, F, G, K, L, MANCH, cision was made to place Discocarpus brasiliensis in OXF, P, U, W); RupununiSavanna, near Maricoubapond synonymyunder Discocarpus essequeboensis. Both near KaranamboRanch, 3?45'N, 59?19'W,Gdrts-van Rijn names were firstpublished by Klotzsch; however, et al. 388 (URV); RupununiDistrict, Kuyuwini Landing, the name D. brasiliensis, published in 1841, re- KuyuwiniRiver, forest along river,205'N, 59'15'W, Jan- sen-Jacobset al. 2903 (URV); Manakobi,Courantyne Riv- mained a nomen nudum until Muller provided it er,Anderson 408 (K), Schomburgks.n. (L, U), Schomburgk with a diagnosis in 1873. Thus D. essequeboensis, 1237 (F), Schomburgk920 (F, G, K, P, W); Cuyuni-Ma- published in 1843, is the oldest legitimate name zaruni Region,Essequibo River 6-8 km downstreamof for this species. Omai, 5-26'N, 58-42'W, Gillespie1573 (MO); Rupununi River, MonkeyPond landing SW of Mt. Makarapan, In addition to those named Discocarpus bras- 3053'N, 58055'W,Maas et al. 7395 (P, U); basin of Es- iliensis Klotzsch, otherspecimens collected by Mar- sequibo Rivernear mouth of Onoro Creek, 1035'N, Smith tius bear the name D. bahiensis Klotzsch, but it 2692 (F, G, NY). SURINAM. Matappi,Corantyne, B. W appears that the latter name has never been pub- 2044 (U); Tapanahoni,Kappler 97 (L, U, W), Kappler2143 lished. It is noteworthythat, aside fromthese nearly (GOET, W), Schomburgk459 (G). 200-year-old collections by Martius, no other col- Notes. Klotzsch's species Discocarpus esseque- lections of Discocarpus have been seen from the boensis was originallybased upon three collections, Atlantic coastal forestof Brazil. Schomburgk35 (pistillate flowers),Schomburgk 659 (staminate flowers), and Schomburgk 706 (mature Discocarpus gentryi S. M. Hayden, sp. nov. fruits).Since staminate material of Discocarpus re- TYPE: Peru. Loreto: Santa Marfa de Nanay, veals few diagnostic characters, and since the fruit- SW of Rfo Nanay, Schunke V 2443 (holotype, ing specimen bears only fragmentarylabel data, the F; isotypes, G, GH, NY, US). Figures 11, 6, 7. pistillate collection, Schomburgk 35, is by far the best choice to typifythe species. The BM specimen Arborvel frutexdioecia, 3-14 m; gemmaterminalis includes abundant flowers that prove importantin glabra;fiores staminati lutei; fiores pistillati 1 (2) per nod- definingthe species (see below). The spelling of the um; pedicellusforum pistillatorum 4-5 mmlongus; fruc- specific epithet adopted here follows that used by tus trilobussymmetricus, seminibus tribus; pericarpium undulatumprofunde, viride; testa cnnamomea. Klotzsch (1843) in contrast to that of the earlier nomen nudum, Discocarpus essequiboensis Klotzsch Trees or shrubs, 3-14 m tall, DBH 35-40 cm. (Archiv. Naturg. 7(1): 201. 1841). Terminal buds similar in staminate and pistillate Discocarpus brasiliensis is here placed in syn- specimens, glabrous to sparsely pubescent, with onymy under Discocarpus essequeboensis. The two two basal knobs. Leaves 7-15 cm long, 3-7 cm entities are virtuallyindistinguishable, and it seems wide; apex acute to acuminate. Inflorescence bracts that recent practice has been to identifymaterial glabrous to somewhat pubescent apically. Staminate fromthe Guianas as D. essequeboensisand Brazilian flowers15-30 per node, brightyellow; sepals 2 mm specimens as D. brasiliensis. In the past, Discocar- long, 1 mm wide; petals (0-)5, glabrous to sparsely pus brasiliensis was supposedly distinguished from pubescent; disk with fingerlike lobes; stamens 5; D. essequeboensis by the presence of small bumps pistillode segments 2-3. Pistillate flowers1 (2) per or muricae on ovaries and fruits of the formerin node; pedicels 4-5 mm long; sepals 3 mm long, 2 contrast to the smooth ovaries and fruitsof the lat- mm wide; petals 5, 2 mm long, 1 mm wide; ovary ter (Muller, 1873; Pax & Hoffmann,1922). How- surface deeply undulate; stigmas reflexed. Fruit ever, the syntypes of D. essequeboensis listed by green, symmetrically3-lobed, 12 mm tall, 15 mm Klotzsch include a fruitingspecimen, Schomburgk diam., 3-seeded, surface deeply sculpted into long 706, which has a surface texture that is obviously undulate ridges with sharp crests. Seeds ca. 8 mm bumpy and identical to other specimens identified diam.; micropylarand basal surfaces somewhatflat- as D. brasiliensis. Further,the lectotype of Disco- tened; testa golden brown. carpus essequeboensis,Schomburgk 35, illustrates a range of developmental stages from very young Distribution. Amazonian Peru and western Bra- flowersjust emerging-fromthe bud to early fruits. zil (Fig. 5); on white sand or clay soil of low, sea- The flowerson this specimen reveal a developmen- sonally inundated forestalong rivers (vdrzea or ta- tal change in ovary surface fromnearly smooth to huampa); 120-150 m altitude. Flowers have been contoured or bumpy as the ovary matures. On the collected fromDecember throughApril; fruits,from basis of these observations, and given the lack of September throughFebruary. 160 Annals of the MissouriBotanical Garden

Figure11. Discocarpusgentryi S. M. Hayden.-A. -Staminateflower; Rimachi Y 3300 (NY). -B. Habit,staminate specimen;Rimachi Y 3300 (MO). -C. Terminalbud; RimachiY 3300 (MO). -D. Disk fromstaminate flower; Rimachi Y 3300 (NY). -E. Habit,pistillate specimen; Gentry et al. 18419 (F). -F. Fruit;Revilla 411 (F). Volume 83, Number2 Hayden & Hayden 161 1996 Revision of Discocarpus

Common Names. "Ucuchahuasi" (Vdsquez & Discocarpus spruceanus Mull. Arg., Linnaea 32: Jaramillo 5487); "Loromicuna" (Ayala 1415). 78. 1863. TYPE: Brazil. Amazonas: Rio Negro above the mouth of the Casiquiare River, Additional specimensexamined. BRAZIL. Amazo- Spruce 3527 (lectotype,selected here, BM; iso- nas: Rio Negronear Ilha Provedenvia,Steward et al. 516 lectotypes, BR, C, E, F, G, GH, GOET, K, LD, (NY). PERU. Loreto: Maynas,Iquitos, Rio Nanay,Que- MO, NY, OXF, P, TCD, W). Figures 12, 1, 2, 8. brada de Morropon,Rimachi Y 3281 (F, MO, NY, RSA); RfoNanay, 03051'S, 73032'W,Vdsquez et al. 7528 (F, NY); Drypeteskrukovii Monach., Phytologia 3: 34. 1948. TYPE: Rfo Nanay at Almendras,03'48'S, 73025'W, Vdsquez& Brazil. Amazonas:Municipality Humayta, near Liv- Jaramillo5487 (F, MO, NY); Iquitos,in the gorgeof the ramento,on Rio Livramento,Krukoff 6703 (holotype, smallsettlement of San Pablo de Cuyanaabove Santa Cla- NY; isotypes,G, US). ra de Nanay,Rimachi Y 3300 (F, MO, NY, RSA); Caiio Iricahua,below Jenuro Herrera, on the leftmargin of Rfo Trees, 10-30 m tall, DBH 30-60 cm. Terminal Ucayali, Encarnaci6n25065 (F); Iquitos, Rfo Nanay,8 buds sexually dimorphic, densely pubescent with bends in the riverabove de MoronaCocha, Revilla 411 very small to no basal knobs in staminate trees, (F, MO, NY); vicinityof Iquitos, Revilla 3598 (F, MO); Rio Itayabelow San Juande Muniches,40 mins.above Iquitos usually glabrous to sparsely puberulent and with with40 hp motor,Gentry et al. 18419 (F, MO); rightmar- two basal knobs in pistillate trees. Leaves 5-12 gin of Zungarococha,primary forest, Ayala 1415 (MO). cm long, 2-5 cm wide; apex acute to acuminate. Inflorescence bracts pubescent. Staminate flowers Notes. Peruvian specimens of Discocarpus re- 15-30 per node, pale yellow; sepals 4-5, 1.5 mm ferred here to D. gentryihave only been collected long, 1 mm wide, pubescent; petals 4-5, glabrous within the last 30 years. The genus was not treated to sparsely pubescent; disk irregularlylobed; sta- in MacBride's (1951) earlier compilation of Eu- mens 4-5; pistillode segments 2-3. Pistillate flow- phorbiaceae for the Flora of Peru, although the ers 1-3 per node; pedicels 1-5 mm long; sepals presence of D. brasiliensis was predicted. When 1.5 mm long, 1 mm wide; petals 5, 1.5 mm long, specimens from Peru with sculpted fruit surfaces 0.5 mm wide; ovary smooth; stigmas horizontal. firstcame to light they were identifiedas D. bras- Fruit brown, subglobose, asymmetrically 3-lobed iliensis, and they are referredto as such in Brako by abortion of 2 (1) carpels, 6-9 mm tall, 6-7 mm and Zarucchi's (1993) checklist. However, D. bras- diam., 1(-2)-seeded, surface smooth. Seed shape iliensis is herein synonymizedwith D. essequeboen- and dimensions unknown (usually shriveled in sis, and, further,the Peruvian collections prove to herbarium specimens); testa brown. be distinctboth morphologicallyand geographically Distribution. Widely in the Amazon fromthis species. As noted in the key, fruitsof D. scatttered and Orinoco River basins of Brazil, Colombia, and gentryihave pronounced surface relief, and pistil- Venezuela (Fig. 5); in vdrzea or rebalse vegetation late flowers are distinctly pedicellate. In contrast, of frequently inundated forest along rivers; often fruitsof D. essequeboensis,though somewhat sculpt- locally abundant. Flowers have been collected from ed, are smoother,and pistillate flowers are sessile January through August; fruits,in November and or nearly so. Additionally, mature capsules of D. December. essequeboensis are brown and the seeds are dark brown,in contrastto the mature capsules of D. gen- Additionalspecimens examined. BRAZIL. Amazo- tryi, which are green and contain golden brown nas: Rio Negro,northern Brazil, Spruce3781 pro parte C, E, F, K, seeds. Careful dissection of staminate flowersof D. (BM, BR, G. GH, GOET, MO, NY, OXF, TCD, W); Airao, Ducke 904 (F, MO, NY, R. UC, US). Mato gentryireveals disk lobes much more elongate than Grosso: proximityof Rio Cristalino,13?13'S, 50?51'W, those of the other two species. Discocarpus gentryi Dovebros(RB). Para': Rio Itacaiuna, cachoeira Grande, has been collected most frequently along river- Fr6es& Black 24513 (U); proximityof Conceivaodo Ar- 120 banks near Iquitos, Peru, especially in the vicinity aguaia, 8?44'S, 49?26'W,Mileski (RB). COLOMBIA. Caquetai: 2 km S of Solano, 8 km SE of Tres Esquinas of Rio Nanay, a blackwater river. There is one ad- on Rfo Caqueta below mouthof Rio Ortequaza,Little & ditional record of the species fromwestern Brazil, Little9604 (US). VENEZUELA. Amazonas: RfoGuain- along the Rio Negro, another blackwater river. ia betweenComunidad and Santa Rita, Wurdack& Ad- The specific epithet commemorates Alwyn H. derley,43349 (NY, S. US); Caio Adobo, 25 km S of San Cargos of Rfo Negro, 1?38'N, 66?58'W, Liesner8634 Gentry (1945-1993), for his many importantcon- (MO, NY); DepartamentoRfo Negro,lower part of the tributionsto the floristicsof Central America and Rio Baria, 1?27'-1?10'N, 66?32'-66?25'W, Davidse northernSouth America. Gentry'scollection of Dis- 27631 (F. MICH, MO, NY); DepartamentoAtabapo, Riv- cocarpus fromthe region around Iquitos, Peru, was erina del Cano Yagua, 03?37'N, 66?35'W, Marin 479 (MO). instrumentalin recognizing these plants as new to science. The syntype collections of Discocarpus spru- 162 Annals of the MissouriBotanical Garden

Figure12. Discocarpusspruceanus Mull. Arg. -A. Habit,staminate specimen; Ducke 904 (F). -1. Terminalbud, staminatespecimen; Mileski 120 (111). -C. Staminateflower, one sepal removed;Ducke 904 (F). -D. Disk from staminateflower; Ducke 904 (F). -E. Terminalbud, pistillate specimen; Spruce 3527 (13M). -F. Immnaturefruit; Davidse 27631 (F). -G. Habit,pistillate specimen; Spruce 3527 (13M). ceanus, Spruce3527 and Spruce 3781, are often versed at G. Further,in many herbaria both curatedtogether leading to potentialconfusion of Spruce collectionsare mountedon the same sheet, the two. Generally,specimens labeled as Spruce and fragmentsfrom the two are oftenmixed to- 3781 are staminateand thoselabeled Spruce3527 getherin the same packet. An additional con- bear fruits,but the numberswere apparentlyre- foundingfactor is thata portionof the duplicates Volume83, Number2 Hayden& Hayden 163 1996 Revisionof Discocarpus

ofSpruce 3781 has been recognizedas the typeof height.In all respects,Jablonski's species matches a different plant, Chonocentrum cyathophorum Chaetocarpusechinocarpus (Acalyphoideae). (Mull. Arg.) Pax & K. Hoffm.(Indeed, one of the twocollections of Spruce 3781 receivedfrom OXF Discocarpusmazarunensis Croizat, Bull. Torr.Bot. was a specimenof Chonocentrummisidentified as Club 75: 400. 1948. TYPE: Fanshawe2124 Discocarpus spruceanus; types of Chonocentrum (NY) = Chaetocarpusschomburgkianus (Kuntze) cyathophorumhave been seen fromOXF, G, and Pax & K. Hoffm. NY, confirmingthat these plantsare notDiscocar- pus.) Of the two syntypes,the fruitingcollections When Croizat (1948) named his new species, thatconstitute Spruce 3527 are by farmore diag- based strictlyon staminatematerial, he notedthat nosticthan the staminatecollection, Spruce 3781, its vegetativefeatures were discordantwith those and thereforethe formerserves better as the type. of Discocarpus.Jablonski (1967) accepted D. ma- This selectionalso avoids possible confusionwith zarunensiswithout comment. In recentyears, Mi- Chonocentrum.Of the severalduplicates seen, the chael Huftannotated several specimensof Disco- specimenfrom BM is particularlyrepresentative. carpus mazarunensis as Chaetocarpus schom- The sexual dimorphismin terminalbuds of D. burgkianus,and Gillespie (1993), followinghis spruceanusis remarkablegiven that species ofDis- lead, excludedthis species fromDiscocarpus. As in cocarpusare otherwiseso similarto each otherveg- the case describedabove, the flowersin the type etatively.The questionwhether staminate and pis- of D. mazarunensishave filamentsfused into a tillatematerial cited heretruly pertain to the same prominentstaminal column with anthers diverging species cannot be dismissedlightly. In southern at differentlevels. Exclusion fromDiscocarpus is Venezuela near the Casiquiare-Negroconfluence, thusjustified. pistillateplants with the characteristicsmooth-sur- faced partiallyaborted fruits occur withstaminate Discocarpus mexicanus Liebm., Skr. Vidensk.- plantswith hairy buds. No pistillatematerial of oth- Selsk. Christiana,Math.-Naturvidensk. K1. 5: er species has been collectedfrom this area. Fur- 309. 1851 = Laportea mexicana (Liebm.) ther,staminate plants with densely hairy buds do Wedd. (Urticaceae)(as per Pax & Hoffmann, notoccur in the Guianas and easternBrazil, where 1922). all pistillatespecimens prove to be D. essequeboen- Discocarpusnicaraguensis Lielbm., Skr. Vidensk.- sis, and they'are similarlyabsent from Peru, where Selsk. Christiana,Math.-Naturvidensk. K1. 5: pistillatespecimens are D. gentryi.We therefore 309. 1851 = Laporteanicaraguensis (Liebm.) interpretstaminate specimens with hairy buds and Wedd. (Urticaceae)(as per Pax & Hoffmann, pistillatematerial with smooth fruits and just a sin- 1922). gle fertilecarpel to be conspecific. At thiswriting, we have seen one recordof Dis- FOLIAR ANATOMY cocarpusspruceanus from Colombia, a floweringsta- minate specimen, Little & Little 9604, collected in Leaf anatomywas foundto varylittle from spe- 1945. cies to species, hence the followingdescriptions pertainto all threespecies. Dimensionscited are averagevalues based on 10 measurementsof each EXCLUDED SPECIES featureper specimen. Discocarpus duckeanus Jabl., Mem. New York Bot. Epidermis(both adaxial and abaxial) uniseriate; Gard. 17: 85. 1967. TYPE: Ducke33825 (NY) cells irregular,partially sclerified; outer periclinal = Chaetocarpus echinocarpus (Baill.) Ducke. walls sclerified;anticlinal walls wavy,sclerified un- evenly,thicker toward the surface,thinner toward Jablonski(1967) based his species on a single the mesophyll(occasional cells of adaxial epi- collectionbearing staminateflowers that, unlike dermissclerified on innerpericlinal wall, thinner genuine Discocarpus,has consistentlypetal-less along anticlinal wall outward);outer periclinal flowerswith eight (or more?)filaments fused into a walls bearingsubcuticular micropapillae (best seen centralcolumn, and subgloboseanthers diverging in Discocarpusspruceanus, Figs. 14, 15, 16). Ad- at variouslevels. Althoughpresent in Discocarpus, axial epidermalcells 15 ,umthick, uniformly bear- fusionof filamentsis restrictedto the base of the ing tannindeposits; cuticle 1-2 ,umthick. Abaxial flower;the filaments,never more than five, diverge epidermalcells 11 ,umthick, occasionally bearing at the same level and terminatein distinctlyelon- tannindeposits; cuticle <1 ,umthick. Stomata re- gate antherspositioned at approximatelythe same strictedto the abaxial epidermis,densely crowded, 164 Annalsof the MissouriBotanical Garden

Figures13-17. Foliarantomy of Disocaqws. 13-16, Disocarpus sprucwus MElL Arg.,Wurdack & Adderly43349 (NY). -13. Leaf cross section;bar = 50 pm. -14. Selerifiedadaxial epidermiswith micropapillae; bar = 10 pm. 15. Selerifiedabaxial epidermisbelow vein; bar = 10 pm -16. Selerifiedabaxial epidermiswith micropapillae; bar = 10 pm. -17. Discocarpusg6uyi S. M. Hayden,Rima Y 3281 (NY). SEM ofstomate with crenulate anticlinal wail of guardcell; bar = 5 pm orientedrandomly, widely elliptic, 18 pm long,15 timeslightly scierified near the adaxial epidermis; pm wide;anticlinal walls forming statal poremi- spongylayer weakly developed, vertically oriented, nutelycrenulate (Fig. 17); subsidiarycells brachy- intercellularspaces large,druses present (Fig. 13). Pc. Large veins composedof concentricarcs of xy- Mesophyllstratified, tannin deposits scattered lem and phloem bounded above and below with throughout;palisade cells well developed,some- groupsof fibers;small veins verticallypercurrent Volume 83, Number2 Hayden & Hayden 165 1996 Revision of Discocarpus

by fibrousbundle sheathextensions sheathed with and Chonocentrumbear the same collectionnum- a single layerof parenchyma(Figs. 13, 20); cells ber,Spruce 3781, as a resultof mixing these clearly of the parenchymasheath frequently bearing pris- distinctplants. Chonocentrumis still knownonly matic crystals(Fig. 19). Areoles well developed, fromthe typecollection, so comparativedata are quadrangular,oriented (Fig. 18). scarce, and Webster(1994b) consideredany pos- The combinedpresence of manysclerified cells, sible relationshipswith this genus to be uncertain. thick-walledfibers, prismatic crystals, and druses Cursoryexamination of severalisotypes of the only renderleaves of Discocarpus physicallytough and species in the genus,C. cyathophorum,shows this durable. While the anatomicalpreparations de- plant to be clearlydistinct from Discocarpus. The scribed above conformgenerally with previously cuplike fused calyx, completeabsence of petals, publishedinformation, neither Gaucher (1902) nor and large funnelformpistillode contrastsharply Levin (1986) mentionedthe existenceof sclerified withDiscocarpus and have no counterpartin Wie- cells in the adaxial layer. landieae. AlthoughWebster (1994b) statedthat the pollen of Chonocentrumis unknown,Punt (1962) DISCUSSION OF RELATIONSHIPS placed the genus in his "Antidesma type,"noting thatthe grainsare "quite different"from those of In this century,Discocarpus has been assigned Discocarpus. Given its ament-likestaminate inflo- to subtribe Discocarpinae of tribe Phyllantheae rescence,fused calyx, and absence ofpetals, Chon- (Pax & Hoffmann,1922, 1931). Kdhler(1965) sug- ocentrum keys readilyto Webster's(1994b) tribe gestedplacement in Bridelieae.Hutchinson (1969) Antidesmeae,a contextwithin which further com- did not include the genus in any of his proposed parativestudies should prove fruitful. The cuplike tribes.Most recently,Webster (1975, 1994b) has calyx of staminateflowers of Hyeronima Allemdo placed Discocarpus in tribeWielandieae, an assem- (FrancoR., 1990) and the funnel-likepistillode of blage of primitivemostly petal-bearing phyllan- Cyathogyne Mull. Arg. (Pax & Hoffmann,1931), thoidgenera. At the genericlevel, Discocarpus has both membersof subtribeAntidesmineae, appear been mostclosely associated with Lachnostylis and directlycomparable to structuresfound in Chono- Chonocentrum;in Webster's(1994b) classification, centrum. all threegenera are placed in Wielandieaeand key Two previouslyunappreciated .characters may out adjacentto each other.In fact,the SouthAfri- serveas synapomorphiesthat argue for a noveltax- can genus Laclinostylis was combinedwith Disco- onomicplacement of Discocarpits (includingLach- carpus by Pax and Hoffmann(1922). nostylis?) near Amanoa (tribe Amanoeae). First, The small treesand shrubsof Lachnostylis grow neotropicalDiscocarpus and Amanoa share the in muchdrier habitats than neotropical Discocarpus unique featureof sclereidsin the epidermis,which and, thus,the plantsappear differentsuperficially. is otherwise unknown in the Euphorbiaceae However,when one looks beyondthe muchsmaller (Gaucher,1902; Levin, 1986) and extremelyrare leaves and highlybranched stems, details such as amongdicots. Presence of foliarepidermal sclere- flowers,areolation, and shape ofterminal buds sup- ids is likelysynapomorphous for these genera. Sec- port Pax and Hoffmann's(1922) earlier view. To ond,staminate flowers of Discocarpus, Lachnostylis, distinguishLachnostylis from Discocarpus, Webster and at least twospecies ofAmanoa, A. nanayensis (1994b) cited thin styles, pubescent staminate W. J. Hayden and A. steyermarkiiJabl. (Hayden, disks, and stamensadnate to the pistillodein the 1990), share an androgynophore-likestructure former.However, cursory examination reveals thick (sometimesdescribed as filamentsconnate to the stylesin Lachnostylissimilar to thoseof Discocar- pistillode);this feature,too, is likely synapomor- pus in at least some specimens,and pubescenceof phous forthese genera(Webster, 1994a). In addi- the disk maybe littlemore than a reflectionof the tion,while several generaof Wielandieaepossess overallhairier aspect of Lachnostylis. Most impor- scalariformperforation plates in thewood, Amanoa tantly,as documentedherein for Discocarpus (Figs. andDiscocarpus (as wellas Lachnostylis)share the 1, 2), staminateflowers of both genera have connate derivedstate of simple perforation plates (Mennega, filamentsadnate to the base of the pistillode. 1987; Hayden et al., 1993). Based on wood fea- Hence, the relationshipbetween Lachnostylis and tures,Mennega (1987) arguedfor the exclusionof Discocarpus seems extremelyclose. Discocarpusfrom Wielandieae. In contrast,relationship with Chonocentrum is Superficially,inflorescences of Discocarpus and muchless likely.Chonocentrum first became asso- Amanoa appear distinctlydifferent; however, their ciated withDiscocarpus by accident.As discussed basic architecturemay prove to be homologous.As above, type collectionsof Discocarpusspruceanus describedand illustratedhere, flowers of Discocar- 166 Annals of the MissouriBotanical Garden

Figures 18-20. Foliar anatomv of Discocarpus. -18. Discocarpus gentryiS. I. Hayden. Vdlsquez& Jaramillo 5487 (NMi_.Areoles between veins in paradermalsection: bar = 1(M)pim. 19. 20. DJiscocarpusessequeboensis Klotzsch. Smith 2692 (Ft. -19. Prismaticcrystals associated with parenchyma cells liningthe areoles:polarized light micrograph: bar = 40 jim. -20. Parenchvmacells liningareoles: bar = 44) jim. pus occur in axillaryclusters. Substructure within reduced bracteal leaves. the differencesbetween these clustersis difficultto discernin the dried. these generaare neithergreat nor absolutein this pressed specimensavailable for study:however. regard.It shouldbe notedthat cvmes of some Af- theirplacement appears to be consistentwith the ricanAmanoa are axillarvto foliageleaves. While sessile cvme diagrammed forAmanoa by Pax and Amanoa is largelvmonoecious. 4manoa anomala Hoffmann(1922). Thus. while the cvmes of Disco- Little(Little. 1969) is dioecious.as is Discocarpus. carpus occur in the axils of foliage leaves and those It is also noteworthythat Punt (1962i and K6hler of neotropical Amanoa are placed in the axils of 1963, distinguishedthe pollen of Discocarpus from Volume 83, Number2 Hayden & Hayden 167 1996 Revision of Discocarpus

thatof otherWielandieae. Although pollen differ- Johansen,D. A. 1940. Plant Microtechnique.McGraw- ences withAmanoa exist, Punt (1962) included Hill, New York. Klotzsch,J. F. 1841. Neue und wenigergekannte suda- Discocarpus as a distincttype under his "Amanoa merikanischeEuphorbiaceen-Gattungen. Arch. Syst. configuration."Thus, inflorescencearchitecture, Naturgesch.7(1): 175-204. flowerstructure, foliar anatomy, wood, and pollen, . 1843. Discocarpus.In: G. Benthamet al., XIV.- all supportclassification of Discocarpusin tribe Contributionstowards a floraof SouthAmerica,-Enu- Amanoeae as superiorto its presentplacement in merationof plants collected by Mr.Schomburgk in Brit- ish Guiana. LondonJ. Bot. 2: 52. Wielandieae. Kdhler,E. 1965. Die Pollenmorphologieder biovulaten Euphorbiaceaeund ihreBedeutung fur die Taxonomie. LiteratureCited GranaPalynol. 6: 26-120. Berlyn,G. P. & J. P. Miksche. 1976. Botanicalmicro- Levin,G. A. 1986. Systematicfoliar morphology of Phyl- technique and cytochemistry.The Iowa State Univ. lanthoideae(Euphorbiaceae). I. Conspectus.Ann. Mis- Press,Ames, Iowa. souriBot. Gard. 73: 29-85. Brako,L. & J. L. Zarucchi. 1993. Catalogueof the Flow- Little,E. L. 1969. New tree species fromEsmeraldas, eringPlants and Gymnospermsof Peru. Catalogode las Ecuador.Phytologia 18: 404-418. Angiospermasy Gimnospermasdel Peru. Monogr.Syst. MacBride,J. F. 1951. Euphorbiaceae.In: Flora of Peru. Bot. MissouriBot. Gard.45. Field Mus. Nat. Hist.,Bot. Ser. 13 (part3A), no. 1: 3- Croizat,L. 1948. Discocarpus.In: B. Maguireet al., Plant 200. explorationsin Guiana in 1944, chieflyto theTafelberg Mennega,A. M. W, 1987. Woodanatomy of the Euphor- and KaieteurPlateau-IV. Bull. TorreyBot. Club 75: biaceae, in particularof the subfamily Phyllanthoideae. 400. Bot. J. Linn. Soc. 94: 11-126. Franco R., P. 1990. The genus Hyeronima(Euphorbi- MUller,J. (Mull. Arg.). 1863. Euphorbiaceae.Vorlaufige aceae) in SouthAmerica. Bot. Jahrb.Syst. 111: 297- Mittheilungenaus dem furDe Candolle's Prodromus 346. bestimmtenManuscript tiber diese Familie.Linnaea 32: Gaucher,L. 1902. Recherchesanatomiques sur les Eu- 1-126. phorbiac6es.Ann. Sci. Nat.,Bot. 8, 15: 161-309. . 1873. Discocarpus.In: Martius,Flora Bras- Gillespie,L. J. 1993. Euphorbiaceaeof the Guianas: An- iliensis 11(2): 13. notatedspecies checklistand key to the genera.Brit- Pax, F. & K. Hoffmann.1922. Euphorbiaceae-Phyllan- tonia45: 56-94. thoideae-Phyllantheae-Discocarpinae.Das Pflanzen- Hayden,S. M. 1995. A TaxonomicRevision of Neotrop- reichIV. 147. XV (Heft81): 202-205. ical Discocarpus(Euphorbiaceae). Master's Thesis, Uni- & . 1931. Euphorbiaceae.In: A. Engler versityof Richmond,Richmond, Virginia. & K. Prantl,Die nattirlichenPfl-anzenfamilien. Ed. 2. Hayden,W. J. 1990. Noteson neotropicalAmanoa (Eu- 19c: 11-253. WilhelmEngelmann, Leipzig. phorbiaceae).Brittonia 42: 260-270. Punt,W. 1962. Pollen morphologyof the Euphorbiaceae M. P. Simmons& L. J. Swanson. 1993. Wood withspecial referenceto .Wentia 7: 1-116. anatomyof Amanoa (Euphorbiaceae). IAWA Journal 14: Webster,G. L. 1975. Conspectusof a new classification 205-213. of the Euphorbiaceae.Taxon 24: 593-601. Hutchinson,J. 1969. Tribalismin the familyEuphorbi- 1994a. Classificationof the Euphorbiaceae. aceae. Amer.J. Bot. 56: 738-758. Ann. MissouriBot. Gard.81: 3-32. Jablonski,E. 1967. Discocarpus.P. 85 in: B. Maguire& . 1994b. Synopsisof the genera and suprageneric Collaborators,The Botanyof the Guyana Highland. Part taxa of Euphorbiaceae.Ann. MissouriBot. Gard. 81: VII. Mem. New YorkBot. Gard. 17. 33-144.