r99rl HAHN: ACANTHOCOCOS t67 Principes, 35(3), IS91, pp. 167-l7l Notes on the Genus Acanthococos Wnrmlt JeMns HIHN Dept. of Botany, Uniuersity of Wisconsin, Madison, WI 53706 Several recent authors (Moore 1973; In the later publication(1903), Barbosa "trlbe'o Dransfieldand Uhl 1986; Uhl and Drans- Rodrigues subdivided the Coco- field 1987) havelisted the SouthAmerican ineae Bentham & Hooker (currently rec- cerrado palm genus Acanthococos Bar- ognized as Cocoeae Martius) into seven bosa Rodrigues as synonymous with the subtribes,Attaleaineae BarbosaRodrigues, more widespread.Acrocomio Martius with- Eucocoineae Drude, Barbosineae Bar- out formal transfer of the type species.In bosa Rodrigues, Bactrisineae Barbosa addition, little or no discussionof the rea- Rodrigues,Astrocaryineae BarbosaRod- sonsbehind this reduction nor of the rela- rigues,Manicariineae BarbosaRodrigues, tionships of the genus and its component and.Leopoldiniineae BarbosaRodrigues. specieshas been offered. Current work on Manicariineae and.Leo poldiniineae are the taxonomy of Paraguayanpalms (Hahn presently placed as subtribes in the tribe 1990, in prep.) has required an exami- Areceae,Attaleaineae (: Attaleinae nation of the genusand its three described Drude) is currently recognizedmore or less species. intact as a subtribe in rhe Cocoeae, and The type species,Acanthococos has- Barbosineaehas been united with Euco- sleri, was described by Joao Barbosa coineae as subtribe Butiineae Saakov Rodriguesin 1900 basedon a collection (Dransfieldand Uhl l986). of Emil Hassler from Ype-hu in eastern The two remaining subtribes, Bactri- Paraguay and illustrated with a colored sineae(with Acanthococos,Bactris, Gui- plate in Barbosa Rodrigues' Sertum Pal- lielma Martius, Martinezia auctores (: rlarum Brasiliensium (1903). In the orig- Aiphanes Willdenow),Amylocar pus Bar- inal publicationoBarbosa Rodrigues spec- bosaRodrigues, and DesmoncusMartius) ulated about the affinities of the newly and,Astrocaryineae (with Acrocomia described taxon concluding that it was Martius and. Astrocaryurn, G. F. W. intermediatelo Bactris N. J. Jacquinand Meyer), are distinguishedfrom the others Syagrus Martius (under the then broadly by the presence of spines on some or all defined Cocos L.) citing the presence of parts of the plant. These are currently spines,free petals in the pistillate flowers, united as subtribe Bactrid.ineae J. D. and what he took to be basal endocarp Hooker (Dransfieldand Uhl l986). pores. This latter feature is anomolousfor No clear characters to differentiate the a spiny member of the Cocoeae.The non- two spiny subtribesfrom each other were spiny members of the tribe are variable in presentedin Barbosa Rodrigues' subtribal pore placement with a basal position most descriptions nor in his analytical key frequent (Uhl and Dransfield 1987). An (1903). Extracting informationfrom Bar- examination of material from the type bosa Rodrigues' generic descriptions, it locality and numerous additional speci- would appearthat the Astrocaryineae are mens from throughout the range of Acan- separatedby the staminate flowers sunken thococosohowever, shows an equatorial in pits on the rachillae accentuated by a rather than basalposition for the endocarp rim of raisedfloral bracts.This character, "honeycomb- Pores' which has beendescribed as I68 PRINCIPES [Vor. 35 like" in appearance (Uhl and Dransfield (1908), and Lem6e(1929, l94l) who 1987), is clearly illustrated in the color included the genus in the otherwise non- plate of Acanthococos hassleri (Barbosa spiny subtribeAttaleinae. Rodrigues, I903) though no mention of it Toledo differentiated Acanthococos is made in the various descriptions of that from genera of subtribe Bactridinae with taxon. The Cuban endemic Gastrococos sympetalousstaminate flowers (Bactris, Morales was not mentioned by Barbosa Guilielma (: Bactris), and' Astryocar- Rodrigues though it also bears the same yum) stating that it occupies a position characteristic rachilla pits. intermediateto theseand the choripetalous A second species from the cerrado of genera of the subtribe (Acrocom'ia, Braz'I, Acanthococos sericea, was de- Aiphanes, andDesmoncus). He calledinto scribed by Burret (1940) based on differ- question the subtribal separation of the ences in tomentum and spine density, spine spiny Cocoeae into groups by Barbosa color, and subterranean stem thickness. Rodrigues pointing out the similarities The author noted the similarities of Acan' betweenAcanthococcos and Acrocomia thococos with Bactris but differentiated it and between Astrocaryum and Bactris. from that genus based on the free petals No mentionwas made of the choripetalous of the pistillate flowers. No mention was Gastrococos. made of endocarp pore position nor of the Wessels-Boer(1965) mentioned the rachilla pits. possibilitythat Aconthococosis synony- Toledo (1952) described a third species mous with Acrocomia but did not make from Brazil, Acanthococos e/nensis, with the new combinationdue to a lack of access two varieties, one each from the States of to material. Sao Paulo (var. emensis) and Minas Gerais Moore (1973) merely listed the name (var. pubifera), based on differences in as synonymous with Acrocornia without stem thickness, spine density, length of additional justification. In Genera Pal- staminate flower pedicels, and apparent tnarunl(Uhl and Dransfield,I9B7), a work differences in anther shape. His under- basedon Moore'snoteso Acanthococos was standing of previously described species informally placed in synonymy under was based entirely on published descrip- Acrocomia. Justifi.cationfor this was that tions and illustrations. An examination of the only difference between the two was specimens shows that stem thickness and in habit (p. 5I9). The genericdescription spine density tend to be variable characters of Acrocomia in Genera Palrnarum in both Acanthococos and the widespread includeslcan thococosand states an equa- Acrocomia aculeata (Jacquin) Lodd. ex torial position for the endocarp pores. In Martius. In addition, basal staminate flow- the subtribal description and in the key to ers are pedicellate in both of these taxa genera,however, a basalpore positionfor while the apical staminate flowers are pre- Acanthococos(under Acrocomia) is main- dominantly sessile. tained. Toledo (1952) also discussed the taxo- Generic boundariesin the Bactridinae nomic position of the genus correctly are fairly well established(Uhl and Drans- describing the illustrating of the equatorial field i987, p. 516) though the relation- rather than basal position of the endocarp ships of the various genera to each other pores. Based on this observationohe placed is still subjectto debate.A basicseparation the genus in subtribe Bactridinae th:us of genera into choripetalous and sympet- correcting the erroneous arguments offered alous generaas per Toledo (1952) would by Barbosa Rodrigues and perpetuated by seemto have considerablevalue though it Dalla Torre and Harms (1907), Pilger is difficult to apply to intermediate genera r99ll HAHN: ACANTHOCOCOS r69 and abun- such as Gastrococosand Aiphanes. The staminodialtube to the corolla,.With finely dividedand inconsistentsystem pro- dant, short mesocarpfibers. the cor- posedby BarbosaRodrigues (1903) relies rection of the erroneous original obser- too heavily on similaritiesin grossstructure vation of endocarp pore position, the large and ignores many of the detailed features number of similaritiesbetween the two gen- held in common. era justify placementof Acanthococosin InGenera Palmarum, no subdivisionof synonymy under Acrocomia. the spiny Bactridinae is employedthough Due to the abundance of edible and the genera are presented in a sequence industrial quality oil in the mesocarp and of proposed evolutionary advancement. endosperm(Balick 1979, Lleras 1985), Reduction in number of pistillate flowers the genusAcrocomia hasbeen the subject and connation of perianth parts, especially of considerablebiosystematic and evolu- in the pistillate flowers, are characteristics tionary study (e.g., Scariot l9B7). The considered most important in assessing taxonomy of the genus, howeveroremains specialization. uncertain(Uhl and DransfieldI9B7). Ear- The genus which has been most fre- lier workers (i.e., Bailey 1941, Glassman quently associatedwith Acrocomia, Gas- 1982) maintained the genus with a large trococos, shares a similar floral arrange- number of speciesmostly basedon natrrow, ment, rachilla chambers, and a connate typological definitions. Recent work con- staminodial ring adnate to the corolla but cerning the systematics of neotropical can be differentiatedby the connate sepals palms, however, supports rather broad of both staminateand pistillate flowers,the speciesconcepts for many groups,partic- pistillate petals distinctly connate basally, ularly those which have been exploited by the erect filaments with basifixed anthers, man or which occur in environmentsinflu- and the absenceof short mesocarp fibers enced by local human populations (Balick adherent to the endocarp. The only other et al. l9\7a" b: Anderson and Balick choripetalous genus in the subtribe, l9BB). As the genusAcanthococos occurs Aiphanes, shares rachilla chambers, free in areas of {requent fire or tilling (Eiten sepals, and a staminodial tube adnate to 1963, I972), these observationssuggest the corolla, but differs in its praemorse that the three describedspecies of Acan- leaflet margins, erect filaments with basi- thococos are merely minor deviations of fixed anthers,basally connate pistillate