SoaresFilho&Machado2003 (2)

7/21/2019 SoaresFilho&Machado2003 (2)

http://slidepdf.com/reader/full/soaresfilhomachado2003-2 1/9

Summary

A new species of Arrojadoa , Arrojadoa marylanae

Soares Filho & M.Machado, is described. The

new species is characterized by its robust, erect

and unbranched stems with woolly ring cephalia,

the high number of ribs, the areoles with flexible

spines, the small tubular flowers with thin and

delicate, spreading perianth segments, and the

small obovoid fruits with translucent and aqueous

funicular pulp.

Resumo

Uma nova espécie de Arrojadoa, Arrojadoa mary-

lanae Soares Filho & M.Machado, é descrita. A

nova espécie se caracteriza por seu caule robusto,

ereto e indiviso provido de cefálios anelares

lanosos, pelo elevado número de costelas, pelas

aréolas providas de espinhos flexíveis, pelas flores

tubulares pequenas com segmentos do perianto

pouco espessos, delicados e patentes, e pelos fru-

tos obovóides pequenos com polpa funicular

translúcida e aquosa.

Description

Arrojadoa marylanae sp. nov. Holotypus: Brazil,Bahia, Mun. Tanhaçu, district of Suçuarana, Serra

Escura, 19 Apr. 2003, M.Machado 28 (HUEFS).

ab omnibus speciebus Arrojadoae habito erecto, planta

longiora latioraque, caule indiviso costis numerosioribus,

spinis setosis flexilibus, cephalio lanosiore, floribus cum

petalis tenuibus expansisque, fructibus cum pulpas aqu-

osa, reliquiis floris basi angustioribus differt.

Figure 1 The flower of Arrojadoa marylanae

Figure 2 (Facing page) Avaldo de Oliveira Soares Filho and Marlyan Coelho, the discoverers of Arrojadoa marylanae,

standing next to a tall, branching specimen

Arrojadoa marylanae –a new Arrojadoa species from

the state of Bahia, BrazilBy Avaldo de Oliveira Soares Filho1 & Marlon Machado2. Photography by Marlon Machado.

1 Departamento de Ciências Naturais, Universidade Estadual do Sudoeste da Bahia, Estrada do Bem Querer,

Km 04, Vitória da Conquista, Bahia, CEP 45100-000, Brazil. Email: [email protected] 2 Departamento de Ciências Biológicas, Universidade Estadual de Feira de Santana, Rodovia BR 116, km 03,

Feira de Santana, Bahia, CEP 44031-460, Brazil. Email: [email protected]





Stem solitary, columnar-erect, 1.5–3m tall, normallyunbranched unless damaged, but sometimes develop-ing a few lateral branches in very old specimens; vasc-ular cylinder rather woody, 20 mm in diameter; tissuesmucilaginous; roots fibrous, much branched and super-ficial. Stem 6–8(10)cm in diameter, segmented by ringcephalia, segments 4–10cm high, the basal segment30-60cm in height (corresponding to the juvenilephase of growth), epidermis dark green; ribs 24–36,low, crenate, rounded, 3–5mm wide, 4–5mm high,5–8mm apart; number of ribs in the same individualvariable between segments. Areoles orbicular, 2mmwide, 7–9mm apart along the rib, with white felt atfirst, later glabrous; spines flexible, thin, aciculate,scarcely differentiated between centrals and radials,12–18 at first, 2–20mm in length with one longer to35mm in length, golden yellow when new, then strawyellow, brownish-grey in older portions of the stem;indeterminate growth of areoles near stem base presentwith new spines to 60mm in length. Fertile part of stem apical, forming a cephalium as broad as the stemapex, later transformed into a lateral, ring-like cephal-ium through continued vegetative growth of the stem,that in this way develops up to 20 and sometimes morering cephalia along its axis, each ring cephalium

8–12mm high, 7–9cm in diameter; cephalium areoleswith abundant cream-yellow to orange-yellow woolinterspersed with long reddish brown bristles to25–35mm. Flowers appear both in the new apicalcephalium and in the older ring cephalia; flower-budscoloured pink to pale pinkish magenta from the earlieststages of their development; flowers diurnal, openingat morning and remaining open until late afternoon,sometimes remaining open through the night and clos-ing in the next morning, tubular, pink to pale pinkishmagenta, 25–30(–35)mm in length, only one third tohalf of its length exserted from the cephalium; peri-

anth 10–12mm in diameter, segments patent, innerperianth segments spatulate, 7–9mm in length, 1mmwide, outer perianth segments scale-like, 1–7mm inlength, 1mm wide; tube nearly cylindric, slightlybroadened near the base (nectar-chamber region),upper region striated longitudinally, 10–12mm inlength, 4–5mm in diameter above the nectar-chamberregion, 5–6mm in diameter at apex just below theouter perianth segments; nectar-chamber region of thetube slightly flattened, 4mm in length, 5mm wide,4mm thick; pericarpel smooth, naked, obovoid, slight-

ly flattened, clearly delimited from the tube, 3–4mm inlength, 4mm wide, 2mm thick; stamens numerous,2mm in length, covering the inner surface of the tubelike a carpet; style 14 mm in length, enclosed in thetube; stigma 6-lobed, each lobe 2mm in length. Fruitobovoid to globose, indehiscent, naked except for thepersistent floral remains attached at apex, expressedfrom the cephalium and falling down from the plant;flower remnant drying black, normally erect, 4mm atbase, shallowly inserted in fruit apex; pericarp smooth,slightly flattened longitudinally, 10–15mm in length,

Figure 4 Fruits of Arrojadoa marylanae (left, three fruits)and Melocactus bahiensis (right, two fruits)

Figure 3 The fruit of Arrojadoa marylanae



10mm in diameter, bright lilac-pink topinkish-magenta, paler towards the base;funicular pulp translucent, aqueous. Seedsnumerous, usually more than 200 per

fruit, cochleariform, glossy, small, 1.1-0.9mm, testa-cells flat, with interstitialpits.

Habitat and distribution

On exposed rock outcrops composed of white quartz rock, in fissures of rock facesor in shallow cavities in the rock filledwith quartz gravel, quartz sand andhumus, in an altitude of 550–750m,within the caatinga vegetation zone in asummer rainfall semiarid region, south-western Bahia, Brazil.

Etymology

The species is named after the biology stu-dent Marylan Coelho, who discovered theplant together with the first author in anexpedition to the Serra Escura inSeptember of 2001. The expedition toexplore the flora of the Serra Escura wasenvisioned by Marylan Coelho, who grewup in Suçuarana, a small village close to

the Serra Escura, and always wanted toexplore it., and the authors wish toacknowledge this by describing the newspecies with her name.

The new species was discovered inSeptember of 2001 during an expeditionorganized by Avaldo de Oliveira Soares

Filho, Professor of Ecology in the NaturalSciences Department of the StateUniversity of south-western Bahia, andMarylan Coelho, biology student in thatuniversity. The goal of the expedition wasto explore the flora of Serra Escura, a hillrising to about 300m altitude above thesurrounding countryside, and located nearSuçuarana, a small village which is in adistrict belonging to the municipality of Tanhaçu, in the south-western region of

the state of Bahia. The lower areas sur-rounding the hill have patches of caatinga vegetation interspaced with cultivated

Figure 5 Seedling plant of Arrojadoa marylanaegrowing in the white quartz gravel

Figure 6 Cliff habitat with dozens of plants of Arrojadoa marylanae.The population consists of plants of all sizes





land, mostly pasture land; on the slopes of the hillgrows a low deciduous dry forest, and the uppermostportion of the hill is a massive outcrop of white quartzrock where grows a sparse rupicolous vegetation. Thename Serra Escura means black mountain, and this is areflection of the sense of humour of the local people,as the mountain is actually white. Soares Filho andMarylan Coelho decided to survey the rupicolous veg-etation of the hill, potentially rich in endemics due tothe isolation of this habitat, and photographs weretaken of all plants they found.

During August 2002 Marlon Machado visited SoaresFilho in Vitória da Conquista, Bahia, and Soares Filho

asked him to identify the cacti he had photographed inhis expedition to the Serra Escura. Machado immed-iately recognized the Arrojadoa species shown in thepictures as something new. A new expedition to thesite was then planned, with the objective of collectingmaterial of the new species for study. In January of 2003 the discoverers of the new species and the sec-ond author visited the Serra Escura, and plants werefound in flower. A few plants were collected and kept

in cultivation by Soares Filho in order to proceed withthe description of the new species. A further visit tothe habitat was made in April 2003 by Soares Filho,Machado and Coelho, this time accompanied byRaymundo Reis Filho, Marcello Moreira, and the Kewbotanists Nigel Taylor and Daniela Zappi. At this timeplants were found in fruit, and the description couldthen be completed.

The accompanying vegetation is composed of smallshrubs in the legume family (Camptosema sp., and Senna sp.), Velloziaceae (Vellozia sp., Barbacenia sp.), Rubiaceae , Malvaceae , and herbs, grasses, and bulbs includingHippeastrum sp. Other cactus species found in the hab-itat of Arrojadoa marylanae are Espostoopsis dybowskii (theSerra Escura is a new locality for this species), Melocactus bahiensis , Melocactus ernestii , Melocactus sp.,Pilosocereus pachycladus , and Tacinga inamoena . In thecaatinga vegetation that surrounds the Serra Escura the

following cactus species can also be found: Arrojadoa penicillata , Arrojadoa rhodantha , Cereus jamacaru ,Coleocephalocereus goebelianus , Melocactus salvadorensis , Melocactus zehntneri , Pereskia bahiensis , Pilosocereus cating- icola , Pilosocereus gounellei , Pilosocereus pentaedrophorus

Figure 9 Pilosocereus pachycladus shares the same habitat with Arrojadoa marylanae

Figure 8 Plant of Arrojadoa marylanae in fruit

Figure 7 (facing page) A small but mature individual of Arrojadoa marylanae



ssp. robustus , Stephanocereus leucostele , Tacinga funalis andTacinga palmadora .

Arrojadoa marylanae readily stands out from all other Arrojadoa species due to its bigger size, thicker andunbranched stems, higher number of ribs, flexiblespines, woollier cephalia, flowers with thin, spreadingperianth segments (Figure 1), fruits with watery pulp

and flower remnant narrower at base and shallowlyinserted in fruit apex. The seeds with flat testa-cells andinterstitial pits could be viewed as another distinguish-ing feature, but this testa morphology is also present in Arrojadoa dinae , as illustrated by Barthlott & Hunt(2000, pag. 104 fig. 49.5). The cephalium seems par-ticularly well-developed in this species when comparedto other Arrojadoa species: it occupies the whole apexof the stem, and is much woollier. Also, growththrough the cephalium compresses it and forces itsstructures to a horizontal position, while in the other

Arrojadoa species growth through the cephalium makesthe cephalium structures only a little inclined.

The overall shape of Arrojadoa marylanae is highly rem-iniscent of Stephanocereus leucostele , and without theflowers and fruits it could easily be mistaken as a mem-

ber of that genus, particularly when old, tall plantsdevelop side branches (Figure 2). However, branchingis extremely rare in this species, only two specimensbranching naturally (without apparent damage to theapical meristem) having been observed.

The flowers of this species show a superficial similar-ity to Melocactus flowers, as they have thin and elon-

gated, spreading perianth segments, and half or moreof the length of the flower is concealed by the cephal-ium wool (Figure 1). The more striking differencebetween the flowers of Arrojadoa marylanae and flowersof other Arrojadoa species is the absence in the first of the convex, fleshy outer perianth segments typical of the later. However, flowers with characteristics similarto those of Arrojadoa marylanae are also found in thegenus, e.g. in Arrojadoa multiflora .

The small fruits with watery pulp are also highly rem-iniscent of Melocactus , and in colour and size (but notin diameter) the fruits of Arrojadoa marylanae matchvery well those of the sympatric Melocactus bahiensis (Figure 4). Melocactus fruits are regularly eaten bylizards, probably for the water content; as a resultlizards disperse the seeds of Melocactus (Taylor 1991).

Figure 10 Melocactus bahiensis growing in the white quartz sand at the habitat of Arrojadoa marylanae

Figure 11 (facing page) Espostoopsis dybowskii is also found at the habitat of Arrojadoa marylanae





It is hypothesized here that the similarities in fruitcharacters between Arrojadoa marylanae and Melocactus could be a case of convergence to the same dispersalagent. Perhaps the similarities of fruit size and waterypulp reflect the preferences of the lizards – a suitablefruit size for nipping, and a suitable water content.Even the more well-developed cephalium of Arrojadoa marylanae could be linked with the mode of dispersalof its fruits, as the tight wool of the cephalium causesthe fruits to be actively expressed from it, falling to theground and thus becoming more conspicuous to thelizards.

Another distinguishing feature of Arrojadoa marylanae is the very regular production of the ring cephalia, asshown by the uniform size of the stem segmentsbetween consecutive cephalia. In Arrojadoa rhodantha and in Stephanocereus leucostele (species that, in commonwith Arrojadoa marylanae, produce many cephalia along

their stems), the stem-segments are often not uniformin size, and vegetative growth of the stem can span formore than one season of growth, with checks of thegrowth during unfavorable periods showing as con-strictions along the stem. These growth checks arecompletely absent in Arrojadoa marylanae ; thus, due to

the very regular production of ring cephalia in this

species, the number of segments can be an indication

of the age of the plant. If each segment corresponds

to one year’s growth, a plant with 20 cephalia is more

than 20 years old, taking into account the growth of

the juvenile phase.

So far Arrojadoa marylanae is known only from the type

locality, where the population is estimated to be a few

thousand plants of all sizes. The number of seedling

plants is particularly high in number and density, and

shows that the species is reproducing well. There are

no current threats to the habitat as the terrain is unsuit-

able for farming, and quarrying is not likely to occur as

the quartz rock is fragile and breaks easily. The only

threat the plants can face is that of collection. It is

hoped that it will not endanger this unique and rare

species.

REFERENCES:

BARTHLOTT, W. & HUNT. D. (2000) Seed-diversity in the Cactaceae sub- fam. Cactoideae . Succulent Plant Research 5. 173p.

TAYLOR, N. P. (1991) The Genus Melocactus (Cactaceae) in Central andSouth America. Bradleya 9: 1-80.

SoaresFilho&Machado2003 (2)

Documents