Jessea and Talamancalia, Two New Genera of the Senecioneae (Asteraceae) from Costa Rica and Panama

Abstract

Two new genera from Costa Rica and Panama, Jessea and Talamancalia, are described. Both genera have elongate corolla lobes, styles with paired stigmatic lines and narrowly rounded penicillate-haired tips, small papillose cells on the achene surface, and neither has tails on the anthers. Jessea has a spiciferous receptacle and carpopodia with many rows of cells. Jessea includes Senecio cooperi, S. megaphyllus, and S. multivenius, with the last as type; the appropriate new combinations are made herein. Talamancalia has mucilage hairs on the achene and carpopodia nearly obsolete. The genus includes Talamancalia boquletensis (Standley) H. Robinson & J. Cuatrecasas and the new species, T. westonii, with the latter as type. Two new genera are established for species of Senecioneae from Panama and Costa Rica that have some of the general appearance of true Senecio L., and have some aspects of PseudogynoxAys (Greenman) Cabrera and Jacmaia B. Nordenstam, but differ in details of the style tips, stigmatic surfaces, corolla lobes, and the setulae of the achene. The first genus, Jessea, includes Senecio multivenius and two other species that in some characters resemble the genus Jacmaia of Nordenstam. The other genus, Talamancalia, includes Senecio boquetensis Standley and a second species, Talamancalia westonii, which is described here as new. Senecio multivenius Bentham ex Oersted of Costa Rica was described almost 150 years ago, and is the best known of the series of superficially similar, but poorly understood species in southern Central America. The group includes the more recently described and closely related S. cooperi Greenman and S. megaphyllus Greenman. The superficially similar Senecio boquetensis was described about 50 years ago from the province of Chiriqui in Panama. All the species mentioned have elongate corolla lobes, style tips rather rounded and bearing an apical pencil of hairs, and small papillose cells on the surface of the achene. In contrast, Senecio sensu stricto has short corolla lobes, truncate style tips without apical hairs, and usually narrow smooth cells on the surface NOVON 4: 48-52. 1994. of the achene. The species all require transfer from Senecio sensu stricto to other genera. The first of the Central American species listed above to be removed from Senecio was the Panamanian endemic S. boquetensis, one of two species transferred by Turner (1991) to the widely distributed neotropical genus Pseudog)noxys (Greenman) Cabrera. The position of the species in Pseudogvnoxvs was accepted by Jeffrey (1992). Jeffrey (1992) also transferred the Costa Rican S. cooperi, S. megaphyvllus, and S. multivenius to the previously exclusively Jamaican genus Jacmaia of Nordenstam (1978). The latter transfer reflected a similarity in habit and the presence of subulate processes in the receptacle in Jacmaia and the S. multi venius group. Of these treatments, the present study accepts the conclusion by Jeffrey that the primarily Costa Rican S. multivenius group and the Panamanian S. boquetensis are not directly related to each other. However, the present study rejects Jeffrey's (1992) placement of the S. multivenius group in Jacmaia and rejects Turner's (1991) and Jeffrey's (1992) placement of S. boquetensis in Pseudogy)nox s. Both elements are named here as new genera. The Central American species listed above all fall among the senecionoid genera of the tribe Senecioneae in the list by Jeffrey (1992) although they are placed in different subgroups. Jacmaia, including the S. multirenius series, is placed by Jeffrey in his Neotropical Group, with mostly woody genera such as Pentacalia. Jeffrey's Jacmaia sensu lato is described as having scalelike processes on the receptacle, style-arms appendaged, a massive carpopodium with 10-12 or more rows of cells, and leaves pinnately lobed. Pseudog)nox s, with S. boquetensis, is placed by Jeffrey in his senecionoid group closer to Erechtites Rafinesque and Emilia (Cassini) Cassini and Senecio L. sensu stricto. Jeffrey states that the styles have trullate appendages, the carpopodia are obscure, and the genus does not have processes on the receptacle. Some of the differences between Jacmaia and Pseudogynoxv s noted by Jeffrey (1992) are retained here to distinguish the two new genera, but This content downloaded from 157.55.39.136 on Thu, 19 May 2016 04:40:03 UTC All use subject to http://about.jstor.org/terms Volume 4, Number 1 1994 49 Robinson & Cuatrecasas Jessea and Talamancalia the new genera are not considered as distant from each other in relationship as suggested by Jeffrey, and they do not belong to the genera in which they are placed by Turner (1991) and Jeffrey (1992). The Senecio multivenius group differs from Jacmaia by three striking features. The style appendage in the Jamaican type species of Jacmaia, J. incana (Swartz) B. Nordenstam, is sharply acute, the stigmatic surface is continuous over the inner surface of each branch, and anther bases have long tails. The style tip of the S. multivenius group is rounded and ends in a pencil of long hairs, the style branch has separated paired stigmatic lines, and the anthers have no tails. In Jacmaia the continuous stigmatic surface is correlated with a greatly enlarged resin duct in the style branch. The style branches of the S. multivenius group and S. boquetensis have only a slender duct. The S. multivenius group is here named as a new genus, Jessea, in honor of the wellknown authority in the Senecioneae, Jesse M. Greenman (1867-1951). The comparative similarity of Senecio boquetensis to Pseudogynoxys is not considered sufficient to include the species in that genus. The Panamanian endemic and the related undescribed Costa Rican species are erect herbs or subshrubs, while species of Pseudogynoxys are scrambling subshrubs or vines. The difference in habit from Pseudogynoxys is particularly marked in the previously undescribed shrubby Costa Rican relative of S. boquetensis. The leaves of the new genus are deeply, pinnately lobed at the base of the blade, while those of Pseudogynoxys are unlobed. The leaf bases have stipulelike continuations of the petiolar wing that clasp the stem, but isolated stipulelike lobes at the bases of unwinged petioles are found in only a few species of Pseudogynoxys (Robinson & Cuatrecasas, 1977). An additional useful feature of the new genus is the fattened and often obviously mucilaginous setulae on the achene wall. The setulae of Pseudogynoxys are smaller and not mucilaginous. The tips of the styles of the new genus are narrowly rounded with an abruptly delimited apical penicillate tuft of hairs, while the style tips of Pseudogynoxys are distinctly pointed and hairs are often continuous along the margins of the tapering tip. The anther appendages of the new genus have thicker-walled inner cells and a channeled center, but the appendages of Pseudogynoxys have more uniformly thickened cells throughout with no central channel. The new genus, with two species, is here named Talamancalia after the Talamanca Mountains of Costa Rica and Panama where it occurs. A comparison of the two new genera shows that in addition to having an armed receptacle and a carpopodium with many rows of cells, Jessea differs from Talamancalia by having the narrow heads clustered in dense corymbiform cymes, in having only eight involucral bracts in each head, and in the less complex and less polarized thickenings of its median endothecial cells. One additional element of interest in the Jessea and Talamancalia relationship is the second species transferred to Pseudogynoxys by Turner (1991), Senecio telembinus Cuatrecasas of the Rio Maldonado on the border of Ecuador and Colombia. The South American species is like S. boquetensis in superficial aspect, having similar enlarged leaf bases, and close-set, ascending secondary veins. The Maldonado species differs from the Panama species, and from much of Senecio sensu stricto, by the lack of lobes on the leaves, by the lack of setulae on the achenes, by the presence of only eight ribs in the achene, and by the short-triangular style tip with a long apical pencil of hairs and strong subapical fringe. The South American species has no woolly pubescence. The species differs more importantly from all the discussed elements by the base of the leaf forming a sheath completely surrounding the stem. The Maldonado species was the basis of a separate genus, Garcibarrigoa, by Cuatrecasas (1986). In spite of the differences, it seems likely that Garcibarrigoa is a rather close relative of Talamancalia. The five genera, Garcibarrigoa, Jacmaia, Jessea, Pseudogynoxys, and Talamancalia, differ from almost all species of Senecio sensu stricto by having long and narrow lobes on the corolla. The lobes in Jacmaia and all of Jessea except the type species are about as long as the throat. The limbs and the lobes of the corolla of Garcibarrigoa are comparatively short with the lobes narrowly triangular rather than narrowly oblong. The new genus Jessea is characterized as follows: Jessea H. Robinson & J. Cuatrecasas, gen. nov. TYPE: Jessea multivenia (Bentham ex Oersted) H. Robinson & J. Cuatrecasas. In receptaculis armatis Jacmaiae similis sed in apicibus stylorum rotundatis et penicillate pilosis in lineis stigmataceis binis et in thecis antherarum base non caudatis