A New Species, Section, and Synopsis of Dalechampia (Euphorbiaceae) from Costa Rica

A New Species, Section, and Synopsis of Dalechampia (Euphorbiaceae) from Costa RicaAuthor(s): W. Scott ArmbrusterSource: Systematic Botany, Vol. 13, No. 3 (Jul. - Sep., 1988), pp. 303-312Published by: American Society of Plant TaxonomistsStable URL: http://www.jstor.org/stable/2419294 .

Accessed: 28/08/2013 13:35

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact [email protected].

.

American Society of Plant Taxonomists is collaborating with JSTOR to digitize, preserve and extend access toSystematic Botany.

http://www.jstor.org

This content downloaded from 128.171.57.189 on Wed, 28 Aug 2013 13:35:49 PMAll use subject to JSTOR Terms and Conditions

http://www.jstor.org/action/showPublisher?publisherCode=aspt

http://www.jstor.org/stable/2419294?origin=JSTOR-pdf

http://www.jstor.org/page/info/about/policies/terms.jsp


Systematic Botany (1988), 13(3): pp. 303-312 (?) Copyright 1988 by the American Society of Plant Taxonomists

A New Species, Section, and Synopsis of Dalechampia (Euphorbiaceae) from Costa Rica

W. SCOTT ARMBRUSTER

Department of Biology and Wildlife and

Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775-0180

ABSTRACT. A synopsis of and key to the 10 species of Dalechampia that occur in Costa Rica are provided. Dalechampia osana is described as a new species from the Osa Peninsula, Costa Rica, where it appears to be endemic. It is very similar to D. shankii (A. Molina) Huft, but differs from that species in having pseudanthial inflorescences with fewer staminate flowers, only 3 fertile pleiochasial arms, and a resin gland. The section, Tiliifoliae, represented by one species in Costa Rica, is described as new.

Although Costa Rica has been a site of active botanical and ecological field work in recent years, many members of its flora remain poorly known and have not been revised systemati- cally in recent times. The genus Dalechampia is one such group that has been a source of taxo- nomic confusion to systematists and ecologists alike (see Armbruster 1982, 1983b, 1984a; Huft 1984). The last comprehensive treatment of this genus in Costa Rica was that in Standley's (1937) Flora of Costa Rica. Since then, several new species have been described or included in the genus (Armbruster 1984a; Huft 1984) and many additional collections have been made.

One apparently undescribed, Mesoamerican taxon in particular has caused much confusion in both ecological and systematic literature. This differs from all other species of the region by having orange-hirsute stems and leaves. It has been collected from the Caribbean slope of Cos- ta Rica and Panama, the Osa Peninsula of Costa Rica, and the Choco Province of Colombia and was referred to as D. "La Osa" by Armbruster (1982).

Recently, Huft (1984) recognized that this material, collected from the Caribbean slope of Costa Rica, had been mistakenly described as a Tragia, and he transferred it to Dalechampia as D. shankii (A. Molina) Huft. At about the same time, I was able to collect and make field observations on populations of the orange-hirsute taxon on both the Caribbean slope of Panama and the Osa Peninsula of Costa Rica. Upon seeing living flowering material, followed by careful re-examination of herbarium specimens, I realized that the orange-hirsute material from the Osa Peninsula differed from D.

shankii in inflorescence morphology and was not conspecific with it. It appears that D. shankii is confined to the Caribbean lowlands in Me- soamerica, and the new undescribed species is restricted to the Osa Peninsula on the Pacific Coast. In this paper the new species from the Osa Peninsula is described and a synopsis of and key to the Costa Rican species of Dalecham- pia are provided.

Dalechampia osana Armbruster, sp. nov. (fig. 1). -TYPE: Costa Rica, Prov. Puntarenas, Osa Peninsula, ca. 5 km west of Rincon de Osa. 8042'N, 83031'W. 50-200 m altitude, 9-12 Jan 1970, W. C. Burger & R. L. Liesner 7278 (holotype: F; isotype: CR).

Differt ab aliis speciebus generis foliis trilobis et integris, bracteis involucellorum staminalium 4, bracteis involucralibus albidis, ungui- culatis trilobis ad medium, caulibus cum pilis patulis croceis, stipulis 7-14 mm longis, 4-9 mm latis; ab D. shankii bracteolis involucralibus la- tioribus, apicibus stigmatum dilatatioribus, bracteolis resiniferis conjunctis et similibus glandium.

Clambering vine; stems twining, terete, 6-9 mm in diam. at growing tips, hirsute with persistent, orange, more or less straight hairs 1-2 mm long and tomentose with straw-colored, persistent, wavy hairs 0.3-0.5 mm long. Leaves alternate, simple; leaf blades palmately trilobed or unlobed and ovate, with major veins 5 or 7 from base, sparsely hirsute with long orange hairs and denser short pale hairs, secondaries ascending, tertiaries scalariform; blades (5)10- 15 cm long, 5-13 cm wide, chartaceous, sparsely sericeous on both surfaces, abaxial surfaces and

303



304 SYSTEMATIC BOTANY [Volume 13

B 1 cm

1cmc

2 mm "

0.5 cm

Q staminate flowers o pistillate flowers

FIG. 1. Dalechampia osana. A. Habit. B. Inflorescence at anthesis. C. Staminate pleiochasium. D. In- florescence in fruit. E. Diagrammatic representation of the arrangement of flowers and bractlets in the inflorescence. Abbreviations: B-involucral bract; b-involucellar bractlets; r-resiniferous bractlets; st.- stipules.

veins with numerous shorter hairs, tips acu- minate, margins plane, entire to sinuate with glandular processes 0.3-0.5 mm long; bases of blades generally deeply (sometimes slightly) cordate, sinuses usually 20-40 mm deep, 4-7 mm wide at petiole, 20-40 mm wide at margins of blades; petioles terete, (2.5)6.0-95(12.0) cm long, 1-2 mm in diam., pubescent as stem; stip-

ules spreading-reflexed, persistent, ovate, striate- veined, 7-14 mm long, 4-9 mm wide, margins with sparse, sessile glands, abaxial surface glabrous, adaxial shortly hirsute; stipels at base of blade 2, 3-4 mm long, with cluster of glands surrounding point of attachment with blade. Inflorescences solitary to several on reduced axillary short-shoots 15-40 mm long at anthesis,



1988] ARMBRUSTER: DALECHAMPIA 305

pubescent as stem, with 2-3 nodes, each with leaf and axillary bud sometimes producing another inflorescence, or leaf early deciduous; distance between ultimate node and proximal involucral bract 5-20 mm at anthesis. Involucral bracts subequal, slightly convex abaxially, white at anthesis, deeply 3-lobed to ca. 1/3 distance to base (middle lobe 20-30 mm long, lateral lobes ca. 20 mm long) distinctly clawed with 3 prominent veins at base (2 additional prominent veins diverge outward from lateral veins ca. 1/4 the distance from the base), limb ca. 25 mm long, 15-20 mm wide, cuneate at base, claw 3-5 mm long, ca. 2 mm wide; involucral bracts hirsute with straw-colored and/or orange hairs on both surfaces, veins on abaxial face densely hirsute- sericeous, margins plane, glandular-fimbriate; stipules of proximal bract ovate, somewhat acute, 7-10 mm long, 8-9 mm wide, striate-veined, glabrous on adcaxial face, hirsute on abaxial face; stipules of distal bract similar to those of proximal bract but 10-14 mm long, 8-11 mm wide. Staminate cymules with stout, hirsute peduncle 3-4 mm long, 1.5-3.5 mm in diam.; involucel of 2 pairs of more or less decussate, free bracts [proximal (=lateral) bracts offset, shifted away from resiniferous bractlets forming the "gland"], bracts densely hirsute with straw-colored to orange antrorse hairs throughout, more dense near base, striate-veined, oval, 8-9 mm long, 6- 9 mm wide, margins finely glandular-denticulate, processes commonly coated with whitish resin; staminate flowers 10, arranged in branched pleiochasium with one terminal flower and three 3-flowered arms; central (=ventral) arms closely appressed to terminal flower, subtended by 3 or 4 oblong-blunt bractlets 3.0-4.5 mm long, ca. 1.5 mm wide, margins laciniate and resiniferous; lateral arms each subtended by 3 or 4 blunt, linear bractlets ca. 3.5 mm long, 1.5 mm wide, margins laciniate and resiniferous; bractlets of sterile pleiochasial arm (op- posite the central fertile arm) ca. 6, resiniferous, subtended by corresponding dorsal involucellar bract, variable in size, generally 3.5 mm long, 4-7 mm wide, arranged concentrically, largest wrapping from the adaxial side, smallest to the center on the abaxial side, tips blunt, margins deeply laciniate; lacinia terete, 1-2 mm long, 0.1-0.2 mm in diam., secreting resin. Sta- minate flowers on stout pedicels 3.5-5.0 mm long, ca. 1 mm in diam., articulated near top, hirsute with erect, straight, long hairs and half-

appressed, short hairs; calyx hispidulous near tip, glabrous at base, splitting into 3-5 lanceolate, acute, spreading segments, ca. 4 mm long, 1-3 mm wide; staminal columns glabrescent, 4- 6 mm long, ca. 1 mm in diam.; stamens 25-30, filaments hirsute distally with long spreading hairs on outer surface, ca. 1 mm long, anther sacs ca. 0.6 mm long. Pistillate cymules sessile, involucel of 2(3) striate-veined bracts with margins irrregularly denticulate, adaxial faces glabrescent, abaxial faces hirsute with straw- colored to orange hair; adaxial (distal) bractlets simple, ovate, overlapped by margins of abaxial bract, 7-9 mm long, 6-8 mm wide; abaxial (proximal) bracts simple, ovate, 7-10 mm long, 10-12 mm wide. Pistillate flowers at anthesis subsessile, sepals 5-6, hirsute with straw-colored to orange hairs, 4-5 mm long, ca. 1.5 mm wide, margins shallowly laciniate, laciniae 0.2- 0.8 mm long, hispidulous; ovaries ca. 2 mm high, ca. 2 mm in diam., densely hirsute with long straw-colored hairs; stylar column curved up- wards (adaxially) for basal 1/2, and downward (abaxially) for distal 1/4 of length, subcylindrical, tapering slightly toward base (columns 0.7-0.8 mm in diam. proximally, 0.9-1.2 mm in diam. distally), 8-10 mm long, puberulent for basal 2/5, stigmatic surface covering distal 3/5, tip with central pit, distinctly dilated (2.5-4 mm wide), forming a down-turned, irregularly 3-lobed plate. In fruit, central pistillate pedicels 5-7 mm long, laterals ca. 2 mm long, pistillate sepals lanceolate, 10-15 mm long, 3-4 mm wide, densely hispid, laciniate, laciniae ca. 2 mm long. Capsules 8-10 mm in diam., densely hirsute with straw-colored to orange hairs; seeds oval, ca. 5 mm long, ca. 4 mm wide, surface only slightly roughened with small ridges, mottled brown and gray, hilum oval, ca. 1 mm long.

Additional specimens examined. COSTA RICA. Pun- tarenas: Osa Peninsula, ca. 5 km west of Rincon de Osa, 8?42'N, 83?31'W, 24-30 Mar 1973, Burger & Gentry 8962 (F); slopes adjacent to airport, 8 Feb 1974, Liesner 1869 (F); road to the Pacific, south and west of the airstrip, 24 Jul 1974, Utley & Utley 1214 (F); Esquinas Ridge, 150-250 m, Jan 1983, Gomez 19672 (F); Parque Nacional Corcovado, ca. 3 km NW of Playa La Llorona on trail to San Pedrillo, 4 Jan 1984, Armbruster & Herzig 83-109 (ALA).

Dalechampia osana would belong to sect. Scan- dentes in the treatment of Pax and Hoffmann (1919). Within this section it would key near D.




tiliifolia Lam. The free staminate involucellar bractlets and laciniate resiniferous bractlets of D. osana, however, indicate its affinities to the members of sect. Dioscoreifoliae (see Armbruster 1984a). Its closest relative in this section, as cir- cumscribed by Pax and Hoffmann (1919), may be D. canescens Kunth, from which it differs in having 3-lobed as well as unlobed leaves, orange pubescence, and resiniferous bractlets subtending the ventral arm (i.e., closest to the pistillate cymule) of the staminate pleiochasium.

In many ways, D. osana most closely resem- bles D. shankii, with which it has been confused in the past. Both species have striking orange pubescence on the stems, leaves, and bracts, and have both unlobed and 3-lobed leaves. Unusual characters shared by both species include the presence of resiniferous fimbria on the margins of staminate involucellar bractlets and the presence of resiniferous bractlets surrounding the ventral arm of the staminate pleiochasium. The two species differ, however, in important reproductive characters, including different num- bers of fertile arms and flowers in the staminate pleiochasium (3 fertile arms and 10 flowers in D. osana, 4 fertile arms and 13 flowers in D. shankii), the presence of a distinct, well devel- oped resin gland in D. osana and its absence in D. shankii, and more dilated stigmas in D. osana (fig. 1). Several differences in vegetative characters include usually shallower leaf sinuses, orange hairs more spreading-hirsute (vs. hirsute-lanate), and generally smaller leaves in D. osana.

Unless the similarity between D. osana and D. shankii is the result of convergence, they would appear to be quite closely related. It would be valuable to know whether their common ancestor was more like D. osana or D. shankii. If the former were the case, then the absence of the resin gland and the fertile pleiochasial arm in D. shankii represents an autapomorphic evolu- tionary reversal of what otherwise appear to be very conservative characters (Armbruster, in prep.). The alternative, that the inflorescence morphology of D. shankii is generally more ple- siomorphic, suggests that D. osana and all other species of Dalechampia with resin glands share a common ancestor, which itself was derived from an ancestor like D. shankii, or that the resin gland has evolved independently in the D. osa-

na line and the line leading to other species with resin glands. Resolution of these phylo- genetic questions must await thorough cladistic analysis of the entire genus.

Dalechampia osana appears to be endemic to the Osa Peninsula of Costa Rica. This distribution may be the result of contraction of a previously broader distribution. Its closest rel- atives, or even conspecifics, may yet be discov- ered in northern South America, as has been the case for several other plants that are pres- ently found in Central America only on the Osa Peninsula (W. Burger, pers. comm.; see Hart- shorn 1983).

Dalechampia osana occurs on the Osa Penin- sula in small natural or anthropogenic disturbances in mature rain forests. It is especially common along stream courses and in regener- ating tree-fall gaps. It may also be a canopy liana in mature forests.

Dalechampia osana secretes copious amounts of whitish resin from the resin gland of the staminate involucel. This resin was collected by the stingless bee, Trigona sp., during observations in January 1983; judging from the gland size (mean = 18.2 mm2, N = 15), however, it should also be visited by larger bees such as Euglossa and Eulaema (Apidae: Euglossini; Arm- bruster 1984b). Stingless bees were not effective pollinators because they were too small to reg- ularly contact the stigmas when collecting resin. The distances between the gland and stigmas (mean = 4.9 mm, N = 14) and the gland and anthers (mean = 5.1 mm, N = 9) strongly suggest that only larger bees such as euglossines are likely to be effective at transferring pollen to the stigmas (see Armbruster 1985).

SYNOPSIS OF COSTA RICAN DALECHAMPIA

The 10 species treated below are arranged by natural sections and species groups that rough- ly reflect phylogeny (Armbruster, in prep.). These sections and species groups deviate con- siderably from the most recent sectional treatment (Pax and Hoffmann 1919); the new sectional classification will be presented formally elsewhere (Webster and Armbruster, in prep.). Specimens examined for this treatment were borrowed from F, MO, NY, and GH and were seen at CR, SCZ, STRI, and DAV. My own collections are deposited at ALA and DAV.




Artificial Key to Dalechampia of Costa Rica

1. Plant a monopodial shrub 0.5-1.5 m tall; leaves simple, pinnately veined, oblanceolate; inflorescence with pink (whitish) involucral bracts; glands of staminate involucels yellow, lacking resin ........ ................................................................................ 6. D. spathulata

1. Plant a twining vine; leaves simple, palmately veined, and more or less ovate or compound; involucral bracts white or green (pink in D. dioscoreifolia); glands of staminate involucels covered with clear, white, yellow, or maroon resin, or gland absent.

2. Leaves palmately compound (may be intermixed with simple leaves). 3. Stems finely retrorse-pubescent to glabrescent; stipules less than 5 mm long; involucral bracts deep

green at anthesis, more or less shallowly cordate, persistent into fruit development; staminate involucellar bractlets connate; resin clear-whitish; pistillate sepals usually 9-10 ............. ....................................................................... 8. D. heteromorpha

3. Stems spreading-hirsute; stipules 8-12 mm long; involucral bracts white at anthesis, clawed, deciduous prior to fruit development; staminate involucellar bractlets free, 4; resin yellow; pistillate sepals 6 . ............................................................... 4. D. websteri

2. Leaves simple, 3-lobed or unlobed. 4. Stems, leaves, and bracts hirsute or lanate with orange hairs; leaves usually both 3-lobed and

unlobed on same plant; staminate involucellar bractlets free, 4, glandular-laciniate. 5. Stems more or less spreading-lanate; leaves usually deeply cordate with narrow sinus; staminate

involucel without distinct resin gland; staminate flowers usually 13 in 4 fertile pleiochasial arms; stigmas weakly dilated at tip, ca. 2 mm across ....... ................... 1. D. shankii

5. Stems spreading hirsute; leaves less deeply cordate with usually open, more or less triangular sinus; staminate involucel with distinct gland producing whitish resin; staminate flowers 10 in 3 fertile pleiochasial arms; stigmas markedly dilated at tip, 2.5-4.0 mm across .... 2. D. osana

4. Stems, leaves, and bracts lacking orange hairs; leaves lobed or unlobed, but usually not both on the same plant (except D. tiliifolia); staminate involucellar bractlets free or connate, not glandular- laciniate.

6. Staminate involucellar bractlets free, 4; involucral bracts clawed, early deciduous prior to fruit development; leaves unlobed, ovate, base deeply cordate.

7. Involucral bracts pink with maroon veins; resin dark maroon; stigmas strongly dilated and peltate, 2.5 mm or more across; pistillate sepals 6-11, deeply pectinate-lobed, central portion much narrower than depth of lobing; stems and leaves finely pubescent with minute hairs, long hairs absent; leaf base with open sinus usually as broad or broader than deep . ........................................................ 5. D. dioscoreifolia

7. Involucral bracts white with green veins; resin pale yellow; stigmas only weakly dilated, not peltate, 1.5 mm or less across; pistillate sepals 5-6(8), laciniate, central portion broader than depth of lobing; stems and leaves densely pubescent with short hairs, sparsely hirsute with long hairs; leaf base with sinus commonly closed by overlapping basal lobes, usually deeper than broad ................................................... 3. D. canescens

6. Staminate involucellar bractlets connate to at least 1/3 of distance from base; involucral bracts persistent into fruit; leaves lobed or unlobed.

8. Staminate involucellar bractlets fused at base, free for over 1/2 length; margins of resiniferous bractlets shallowly laciniate; involucral bracts cream-colored at anthesis (green in fruit), shallowly 3-dentate at apex; leaves dimorphic, 3-lobed and unlobed usually on same plant; stipules lance-linear, usually over 6 times as long as broad, caducous ....... 7. D. tiliifolia

8. Staminate involucellar bractlets completely connate into cup-like or bilabiate structure subtending staminate flowers and resin gland; margins of resiniferous bractlets entire; involucral bracts greenish to white at anthesis, deeply 3-5-lobed to 1/3 bract length (sometimes 2-lobed or entire in D. heteromorpha); leaves usually monomorphic (sometimes dimorphic in D. scandens and D. heteromorpha); stipules lanceolate to lance-ovate, less than 5 times as long as broad, persistent.

9. Leaves nearly always 3-lobed, rarely unlobed; involucral bracts pale green to white at anthesis, deeply 3-lobed to ca. 1/2 distance from tip; resin produced by gland white . . .................................................................. 10. D. scandens

9. Leaves unlobed and more or less cordate, almost never 3-lobed (D. heteromorpha may have compound and 2-lobed leaves intermixed); involucral bracts deep to pale green at




anthesis, unlobed to deeply 3-lobed (D. heteromorpha) or deeply 5-lobed; resin produced by gland clear or yellow.

10. Leaf base cordate with deep, narrow sinus 1-2 cm deep, 5-10 mm broad; lamina simple, unlobed, ovate; involucral bracts pale green at anthesis, 5-lobed with 7-9 main veins from base; resin yellow ........ .................... 9. D. arenalensis

10. Leaf base weakly cordate with usually broad shallow sinus 1.0(1.5) cm or less deep; lamina simple, unlobed, or simple leaves intermixed with compound and 2-lobed leaves; involucral bracts deep leaf-green at anthesis, deeply 3-lobed or unlobed (sometimes asymmetrically 2-lobed) with 5 main veins from base; resin clear . . .

........................................................... 8. D. heteromorpha

A. Section Dioscoreifoliae Pax & Hoffmann, Das Pflanzenreich IV. 147. XII(68):45. 1919.-Vines with free staminate involucellar bracts and laciniate resiniferous bractlets.

Species Group 1-Leaves simple; pistillate sepals 5-6, with broad central strap and relatively shallow lobing.

1. DALECHAMPIA SHANKII (A. Molina) Huft, Ann. Missouri Bot. Gard. 71:341. 1984.-Tragia shankii A. Molina, Ceiba 11:68. 1965.-TYPE: Costa Rica, Prov. Limon, drainage of Rio Reventazon, 15 m, 23 Oct 1951, Shank & Molina 4427 (F!).

This species is infrequently collected but is apparently widely distributed on the lower Ca- ribbean slope of Costa Rica and Panama (fig. 2). It generally occurs in wet primary forests or lightly disturbed forests below 300 m elevation. It is unique among Mesoamerican Dalechampia in lacking a distinct resin gland in the staminate cymule and having bright orange pubescence on the stems and leaves. It has been hypothe- sized that this species is pollinated by pollen- collecting bees (Armbruster 1984b), but critical observations are lacking and need to be made prior to destruction of the forest habitats in which it occurs. Dalechampia shankii blooms at least in the dry season, or perhaps year-round.

2. DALECHAMPIA OSANA Armbruster, described herein.

Dalechampia osana appears to be restricted to lowland primary and secondary forests of the Osa Peninsula (fig. 2). It bears large resin glands and its pollinators are probably female euglossine bees (see Armbruster 1984b), but critical observations are lacking. It blooms in the dry season.

3. DALECHAMPIA CANESCENS Kunth subsp. FRIED- RICHSTHALII (Muell. Arg.) Webster & Huft,

Ann. Missouri Bot. Gard. (in press). 1988. Dalechampia friedrichsthalii Muell. Arg., Flora LV:45. 1872.-TYPE: Nicaragua, Rio San Juan, Friedrichsthal 683 (G).

Dalechampia canescens has been collected in central and eastern Panama and in Nicaragua. The type collection for subsp. friedrichsthalii is from the Costa Rica-Nicaragua border at Rio San Juan, thus D. canescens subsp. friedrichsthalii probably occurs along the Caribbean lowlands of Costa Rica. Nevertheless, it appears to be quite rare. Dalechampia canescens subsp. canescens [type: Colombia, Mariquita, Humbolt s.n. (P)] occurs in Colombia and western Venezuela. The two subspecies are only dubiously separable, and should perhaps be synonymized. Dalecham- pia canescens has a large resin gland, and it is pollinated by resin-collecting, female euglossine bees in Venezuela (Armbruster, unpubl. obs.). Its blooming season in Costa Rica is not known.

Species Group 2-Leaves compound; pistillate sepals 5-6, with broad central strap and relatively shallow lobing.

4. DALECHAMPIA WEBSTERI Armbruster, Syst. Bot. 9:272. 1984.-TYPE: Costa Rica, Prov. He- redia, Finca la Selva, ca. 3 km SE Puerto Viejo de Sarapiqui, ca. 45 m, 21 Dec 1979, Armbruster & Herzig 79-207 (DAV!).

Dalechampia websteri is a distinctive species with compound leaves like D. heteromorpha, but with inflorescences typical of section Diosco- reifoliae. It has been collected from scattered sta- tions in the lowland to mid-elevations (300 m or less) on the Caribbean slope of Costa Rica and western Panama (fig. 2). Dalechampia websteri has moderately large resin-producing glands, and it is pollinated primarily by female euglossine bees (Armbruster 1984a, 1984b). It apparently blooms mostly in the dry season.




fO ~NICARAGUA 0 D shank/ii 0 D osona A D. websferi

l A V. dioscoreifolia

S t~~~~COT o RICA

-90

-80 I

FIG. 2MaofCsR 85? 84d o h D ots

FIG. 2. Map of Costa Rica showing dis-tribution of D. shankii, D. osana, D. websteri, and D. dioscoreifolia.

Species Group 3-Leaves simple; pistillate sepals 6-11, with deep lobing and narrow central strap.

5. DALECHAMPIA DIOSCOREIFOLIA Poeppig in Poeppig & Endlicher, Nov. Gen. Spec. Plant. III:20. [1841]1845.-TYPE: Peru, Maynas, Poeppig 2163 (B).

Dalechampia dioscoreifolia can be distinguished from all other viny species of Dalechampia in Costa Rica and Panama by its showy pink involucral bracts. It is known from primary (or secondary) lowland wet or moist forests. In Cos- ta Rica, D. dioscoreifolia has been collected from scattered localities on both the Pacific and Ca- ribbean slopes (fig. 2). Recent collections, however, are few; it appears that this forest-dwell- ing species has become very uncommon in Costa Rica because of the deforestation of the past fifty years. It is common in central Panama and has been collected in Caribbean Nicaragua. Dale- champia dioscoreifolia has a large resin gland and in Panama is pollinated by resin-collecting female euglossine bees (including Eulaema spp.) (Armbruster and Herzig 1984). It blooms in Panama (and probably Costa Rica) from No- vember to April (Armbruster and Herzig 1984; cf. Croat 1978).

B. Section Cremophyllum (Scheidw.) Baillon, Etude Gen. Euphorb. 487. 1858. Cremophyllum Scheidw., Bull. Acad. Bruxelles IX:23. 1842.- Small, erect, monopodial shrubs, leaves simple, pinnately veined; staminate involucellar bracts free.

6. DALECHAMPIA SPATHULATA (Scheidw.) Bail- lon, Etude Gen. Euphorb. 487. 1858.-Cre- mophyllum spathulata Scheidw., Bull. Acad. Bruxelles IX:23. 1842.-TYPE: Brazil, described from cultivatd plants.

Dalechampia roezliana Muell. Arg. in DC., Prodr. 15(2):1233. 1866.-TYPE: Mexico, Veracruz, Sontecomapan, Roezl s.n. (G).

Dalechampia spathulata is unique among the Mesoamerican species in being a monopodial shrub. It is known from Costa Rica by a single collection from near Tilaran made in 1935. It appears to occur only in the understory of primary lowland to premontane wet forest. This species is either very rare or extinct in Costa Rica; collectors should be on the lookout for it in the Caribbean lowlands and eastern slopes of the cordilleras. The nearest other collections are from Honduras, Belize, Guatemala, and Mexico. This species is particularly interesting because, although it is probably derived from




resin-secreting ancestors (Armbruster 1983a), it secretes monoterpene fragrances from a structure homologous to the resin gland (Whitten et al. 1986) and is pollinated by male Eulaema (Ap- idae: Euglossini) (Armbruster and Webster 1979). Dalechampia spathulata blooms year-round in Mexico.

C. Dalechampia L. Section Tiliifoliae Webster & Armbruster, sect. nov.-TYPE: Dalechampia tiliifolia Lam.

Differt ab aliis sectionibus generis bracteis involucellorum staminalium connatis 1/3 longi- tudinum et bracteolis resiniferis laciniatis. Vines; staminate involucellar bracts fused for ca. 1/3

length, 4 lobes asymmetrically arranged, one subtending the resin gland, 3 subtending the staminate flowers; resiniferous bractlets laciniate.

7. DALECHAMPIA TILIIFOLIA Lam., Encycl. 11:257. 1786. -TYPE: Probably collected in Peru, Jo- seph Jussieu s.n. (P).

Dalechampia tiliifolia is quite common in much of the lowland Pacific slope of Costa Rica (fig. 3). It is found in disturbances in primary moist to dry forests, in secondary forests, and in de- graded secondary scrub and roadsides. It is generally found in drier more open habitats than D. dioscoreifolia and other wet-forest species (Armbruster and Herzig 1984), but in moister habitats than D. scandens in Costa Rica. Dale- champia tiliifolia has very large inflorescences with large resin glands. It is pollinated in Costa Rica and Panama by female euglossine bees (primarily Eulaema spp.) (Armbruster and Her- zig 1984). It blooms only in the dry season.

D. Section Dalechampia. Vines with simple or compound leaves; staminate involucellar bracts more or less completely connate or bilabiate; margins of resiniferous bractlets entire.

Species Group 1-Vines with all trifoliolate leaves, mixed trifoliolate and simple, unlobed (rarely lobed) leaves, or, rarely, all simple, unlobed leaves; involucral bracts leaf-green at anthesis.

8. DALECHAMPIA HETEROMORPHA Pax & Hoff- mann, Das Pflanzenreich IV. 147. XII(68): 26. 1919. -TYPE: Costa Rica, Rio Grande, San Ramon, Brenes 14414 (B).

Dalechampia heteromorpha may turn out to be a synonym of D. cissifolia Poeppig (see Webster and Burch 1968), but until a thorough systematic study is undertaken, I have chosen to refer all Mesoamerican populations with both trifoliolate and simple leaves, and with "hetermor- pha-like" inflorescences, to this species. Dale- champia heteromorpha is probably the most common species of Dalechampia in the moist to wet forests of lowland and premontane Costa Rica (under 1200 m). It is common in secondary vegetation, including roadside scrub, and as an understory vine. The inconspicuous inflorescences bear moderately small resin glands and are pollinated by small to medium-sized bees, including worker Trigona spp. (Apidae: Mele- ponini) and female Hypanthidium spp. (Mega- chilidae: Anthidiini) in Costa Rica and Panama (Armbruster 1984b; Armbruster and Herzig 1984). Dalechampia heteromorpha blooms year- round.

Species Group 2-Vines with simple, unlobed or 3-lobed leaves; involucral bracts pale green to white at anthesis.

9. DALECHAMPIA ARENALENSIS Armbruster, Syst. Bot. 9:272. 1984.-TYPE: Costa Rica, Prov. Alajuela, 5 km W La Fortuna, 370 m, 3 Feb 1980, Armbruster & Herzig 79-215 (DAV!).

Dalechampia arenalensis is a very rare species, having been collected only twice in two nearby localities, and appears to be restricted to the north slope of Volcan Arenal (fig. 3). It may be threatened with immediate extinction due to deforestation in that area. In the only site at which I have found it, it occurs along the for- ested margins of a stream, in remnants of wet lowland-premontane transition forests. It has relatively large glands and is visited and probably pollinated by female Euglossa sp. and perhaps other euglossine bees (Armbruster 1984a). Flower have been collected in January and Au- gust; it may bloom year-round.

10. DALECHAMPIA SCANDENS L. Sp. P1. 1054. 1753.-TYPE: Presumably in Hortus Clif- fortianus Herb. (BM).

Dalechampia scandens is the most common and widespread species of Dalechampia in the drier parts of the Pacific slope of Costa Rica (fig. 3). It is especially common in Guanacaste. It occurs




N I NICARAGUA . . ........... .I@1 ti/ilfo/la 96 o 0 1? heteromorpho

A 'S' A 12D. arena/ensis A A A D. scandens

90~~~~

80~~~~~~

F.. pfoRcs id i OfTA .ICA t

| X (~~~~~~o PANAMA l

l O,~~~ 30 60 km 85? 84? 830 820

FIG. 3. Map of Costa Rica showing distribution of D. tiliifolia, D. heteromorpha, D. arenalensis, and D. scandens.

at the margins of dry forests, in secondary scrub, along roadsides and in other weedy habitats. In Costa Rica, the inflorescences have large resin glands and are probably pollinated by euglossine bees and possibly Hypanthidium spp. (see Armbruster 1984b, 1985). It blooms only in the dry season in Guanacaste.

ACKNOWLEDGMENTS. I thank Servicios de Parques Nacionales of Costa Rica for permission to work in Corcovado and Santa Rosa national parks, to Michael Kay and James Lewis of Costa Rica Expeditions for logistic assistance, William Burger and Michael Huft for making loans of material from F, Alan Young for sending me collections of Dalechampia, Sylvia Kelso for help in measuring specimens, Donald Borchert and Kay Holmes for the figures, Nancy Anderson for typing, William Burger, Michael Huft, Sylvia Kelso, David Murray, and Grady Webster for making com- ments on the manuscript, and Christa Hollerbach for checking the Latin diagnoses. Financial assistance supporting this work was provided by the National Science Foundation (BSR-8509031) and the University of Alaska.

LITERATURE CITED

Armbruster, W. S. 1982. Seed production and dis- persal in Dalechampia (Euphorbiaceae): Divergent patterns and ecological consequences. Amer. J. Bot. 69:1429-1440.

* 1983a. Evolution and chemistry of pollinator rewards in the genus Dalechampia (Euphorbi- aceae). Amer. J. Bot. 70(5, pt. 2):104.

* 1983b. Dalechampia scandens. Pp. 230-233 in Costa Rican natural history, ed. D. H. Janzen. Chi- cago: University of Chicago Press.

1984a. Two new species of Dalechampia (Eu- phorbiaceae) from Mesoamerica. Syst. Bot. 9:272- 278.

1984b. The role of resin in angiosperm pollination: Ecological and chemical considerations. Amer. J. Bot. 71:1149-1160.

1985. Patterns of character divergence and the evolution of reproductive ecotypes in Dale- champia scandens (Euphorbiaceae). Evolution 39: 733-752.

and A. L. HERZIG. 1984. Partitioning and sharing of pollinators by four sympatric species of Dalechampia (Euphorbiaceae) in Panama. Ann. Missouri Bot. Gard. 71:1-16.

and G. L. WEBSTER. 1979. Pollination of two species of Dalechampia (Euphorbiaceae) in Mexico by euglossine bees. Biotropica 11:278-283.

CROAT, T. B. 1978. Flora of Barro Colorado Island. Stan- ford: Stanford University Press.

HARTSHORN, G. S. 1983. Introduction to the plants. Pp. 118-157 in Costa Rican natural history, ed. D. H. Janzen. Chicago: University of Chicago Press.

HUFT, M. J. 1984. A new combination in Dalechampia (Euphorbiaceae). Ann. Missouri Bot. Gard. 71:341.

PAx, F. and K. HOFFMANN. 1919. Euphorbiaceae- Dalechampieae. Pp. 1-59 in Das Pflanzenreich




IV.147.XII(Heft 68), ed. A. Engler. Leipzig: Verlag von Wilhelm Engelmann.

STANDLEY, P. C. 1937. Flora of Costa Rica. Publ. Field Mus. Nat. Hist., Bot. Ser. 18.

WEBSTER, G. L. and D. BURCH. 1968. Flora of Panama: Euphorbiaceae. Ann. Missouri Bot. Gard. 54: 211- 350.

WHITTEN, W. M., N. H. WILLIAMS, W. S. ARMBRUSTER, M. A. BATTISTE, L. STREKOWSKI, and N. LINDQuIsT. 1986. Carvone oxide: An example of convergent evolution in euglossine pollinated plants. Syst. Bot. 11:222-228.

Addendum for Syst. Bot. 9:272-278. 1984: Part of the description of Dalechampia websteri (p. 272) was in- advertently omitted. The description of the stipules, petioles, and stipels should read: Stipules reflexed, persistent, lanceolate, acute, entire, and non-glandular except at base, indistinctly striate-veined, sparsely strigose on both faces, sericeous hirsute on abaxial face and margins, 8-12 mm long, 2-3 mm broad; petioles pubescent as the stem, terete, 2-7 cm long, 0.5-1.5 mm in diam.; stipels at base of leaflets usually 4, lanceolate, gland tipped, 2-4 mm long, 0.3- 0.5 mm wide, margins with a few sessile reddish glands.

Announcement Systematic Botany Monographs. Currently available from ASPT:

Volume 18. Monograph of the Eremolepidaceae, Job Kuijt, 60 pp., January 1.988. ISBN 0-912861-18-5. US orders: $8.00; non-US orders: $8.50.

Volume 19. Revision of Tristerix (Loranthaceae), Job Kuijt, 61 pp., January 1988. ISBN 0- 912861-19-3. US orders: $8.00; non-US orders: $8.50.

Volume 20. Revision of Cuphea Section Heterodon (Lythraceae), Shirley A. Graham, 168 pp., March 1988. ISBN 0-912861-20-7. US orders: $20.00; non-US orders: $20.50.

Volume 21. Systematics of Coursetia (Leguminosae- Papilionoideae), Matt Lavin, ca. 165 pp.,

April 1988. ISBN 0-912861-21-5. US orders: $20.00; non-US orders: $20.50.

Terms: Payment in US currency must precede shipment. Not available as exchange. No discounts al- lowed on single orders. No refunds. Price is postpaid. Make checks payable to American Society of Plant Tax- onomists and send with order to: Systematic Botany Monographs, University of Michigan Herbarium, North University Building, Ann Arbor, MI 48109- 1057.

Standing order customers receive a 10% discount beginning with the current volume and are billed with shipment.

Information about previously published volumes and instructions for contributors may be obtained by writing to the editor, Christiane Anderson, at the above address.



Documents

A New Species, Section, and Synopsis of Dalechampia (Euphorbiaceae) from Costa Rica