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Background and Aims: In Mexico, the Neotropical genera of Annonaceae tribe Miliuseae, including Sapranthus, Stenanona and the Mexican endemic genus Tridimeris, are particularly diverse and many of their species are endemic to this country. This diversity is not fully documented and many new species have been discovered as a result of recent botanical explorations in southern Mexico. Here, we describe a new species of Stenanona.Methods: We collected a new species of Stenanona during field work in a little known karst forest area located in the highlands of Chiapas, Mexico. The new species was recognized using the unique combination of features through comparisons with morphologically similar species and literature review. We assessed its conservation status by calculating its extent of occurrence (EOO) and its area of occupancy (AOO) using the GeoCAT tool and applying the IUCN Red List Categories and criteria.Key results: A new species of Annonaceae, namely Stenanona morenoi, endemic to karstic forests of southern Mexico, is described and illustrated. According to the criteria established by the IUCN, it is possible to tentatively determine the species as Critically Endangered (CR B1ab (iii)).Conclusions: Based on its general floral morphology, S. morenoi is hypothesized to belong to subclade A of the Desmopsis-Stenanona clade. Within this lineage, S. morenoi shares several morphological features with S. migueliana, S. stenopetala and S. zoque.

The phylogenetic relationships among members of the Neotropical clade of Miliuseae were inferred using Bayesian inference, maximum likelihood, and parsimony on a dataset of six plastid regions (ndhF, matK, psbA-trnH, rbcL, rps16-trnQ, and trnL-F). The phylogenetic hypothesis obtained indicate that the Neotropical clade of Miliuseae is a monophyletic group, composed of two distinct lineages: the first comprises the genera Sapranthus and Tridimeris, and the second is composed of Desmopsis, Stenanona, and two potentially new taxa, which together form the Desmopsis-Stenanona clade. However, the relationships within the Desmopsis-Stenanona clade are not fully resolved; the phylogenetic results indicate that Desmopsis and Stenanona, as currently circumscribed, are not monophyletic. The morphological characteristics that distinguish each genus and potential synapomorphies are discussed. We conclude that the observed variation in floral and fruit characteristics among the members of the Desmopsis-Stenano...

Based on phylogenetic and morphological evidence, Tridimeris chiapensis Escobar-Castellanos & Ortiz-Rodr., sp. n. (Annonaceae), a new species from the karst forest of southern Mexico, is described and illustrated. The new species differs from Tridimeris hahniana, the only described species in the genus, in that the latter has flowers with sepals densely tomentose outside, one (rarely two) carpel(s) per flower and fruits densely covered with golden-brown hairs, while Tridimeris chiapensis has flowers with glabrous sepals outside, two to five carpels per flower and glabrous fruits. Furthermore, a shallow triangular white patch at the base of the inner petals is found in Tridimeris chiapensis, a morphological character shared with the sister genus Sapranthus but absent in Tridimeris hahniana. Geographically, both species occur allopatrically. With just one known locality and seven individuals of Tridimeris chiapensis recorded in one sampling hectare, and based on application of the criteria established by the IUCN, we conclude tentatively that the species is critically endangered.

A taxonomic revision of the genus Sapranthus is presented. Within the genus Sapranthus 8 species are recognized, 2 of which are new. Distinguishing morphological characteristics are discussed, and a dichotomous key to all species is given. The species treatments include descriptions, full synonymy, geographical and ecological notes, vernacular names, and taxonomic notes. Distribution maps are presented of all species, and a complete identification list of exsiccatae examined is included.

Premise of the study: Tribe Miliuseae (~25 genera and ~510 species) includes a substantial part of the species and generic diversity in the pantropical flowering-plant family Annonaceae (~108 genera and ~2400 species). Previous molecular phylogenetic analyses have failed to resolve the backbone phylogeny of the tribe, impeding biogeographical and evolutionary studies. We use a dense generic taxon sample (~89% of generic diversity in Miliuseae) and plastid DNA sequence data (~7 kb) to clarify the phylogenetic relationships of and within the tribe. Methods: Parsimony and Bayesian phylogenetic reconstructions and ancestral character-state reconstructions of several reproductive characters were performed. Key results: Dendrokingstoniae, Monocarpieae, and Miliuseae are recovered in a strongly supported clade, and each tribe is strongly supported as monophyletic. Miliuseae are characterized by a synapomorphic cryptoaperturate/disulculate pollen apertural system. Stenanona is shown to be nested within the paraphyletic genus Desmopsis. The only Neotropical clade (Sapranthus, Tridimeris, Desmopsis, and Stenanona) in the predominantly Asian Miliuseae is shown to be closely related to an undescribed genus from continental Southeast Asia and the Indo-Malayan and Austral-Pacific genus Meiogyne. Ancestral character-state reconstructions of several reproductive characters that are diagnostically important at the generic level indicate a considerable degree of homoplasy. Conclusions: The results improve our understanding of the relationships of and within Miliuseae, but parts of the backbone of the phylogeny remain poorly supported. Additional data from variable nuclear markers or reduced-genome-representation approaches seem to be required to further resolve relationships within this recalcitrant clade

Two new species of Annonaceae, Sapranthus viridiflorus G. E. Schatz and Unonopsis stevensii G. E. Schatz, are described from Mesoamerica. Color photographs of the new species can be accessed over the World Wide Web by searching the name in WZTROPICOS at http://www.mobot.org/ Pick/Search/pick.html. RESUMEN. Se decriben dos especies nuevas de Annonaceae, Sapranthus viridiflorus G. E. Schatz y Unonopsis stevensii G. E. Schatz, de Mesoambrica. Fotograffas a color de las especies nuevas son accesibles buscando el nombre en las piginas de Internet de WZTROPICOS en la siguiente direcci6n: http://www.mobot.org/Pick/Search/pick.html. In anticipation of the upcoming publication of the Flora de Nicaragua, I provide here names and descriptions for two undescribed species of Annonaceae from Mesoamerica. Sapranthus viridiflorus G. E. Schatz is the southernmost of seven species in a genus extending from the states of Sinaloa and Veracruz, Mexico, to the province of Los Santos, Panama. In contrast to the other species of Sapranthus B. C. Seemann, which occur in seasonally dry deciduous forest and possess membranaceous reddish to deep purple petals with evident venation, S. viridflorus occurs in moist to wet evergreen forest and exhibits thick, fleshy green petals lacking venation at maturity. Unonopsis R. E. Fries is a genus of ca. 40 species distributed from Belize to Bolivia in wet, evergreen forest, with 6 species currently known from Mesoamerica, and an additional 4-5 new species awaiting description. Although not yet known from Nicaragua, Unonopsis stevensii G. E. Schatz is to be expected in the southeastern region of the country along the Rio San Juan just to the north of Cerro Coronel and Barra del Colorado in Costa Rica, the sole locality for the new species. Sapranthus viridiflorus G. E. Schatz, sp. nov. TYPE: Costa Rica. Heredia: La Selva Biological Station of the Organization for Tropical Studies, 4 km S of Puerto Viejo de Sarapiqui, 10026'N, 84001'W, 35 m, 15 Feb. 1984 (fl), G. E. Schatz 963 (holotype, MO; isotypes, CR, WIS). Figures 1, 2, and http://hoya.mobot.org/ mobot/research/image/01602308O001.jpg, http: //hoya. mobot. org/mobot/research/image/ 01602308002.jpg A speciebus aliis Sapranthi petalis enervibus carnosis viridibus et carpellis 2-5 differt. Tree to 12 m tall, the young branches brownish gray tomentose. Leaves membranaceous, the petiole 0.4-1.0 cm long, shallowly canaliculate, brownish gray tomentose; lamina elliptic to oblong-obovate, 5.6-29.8 cm long, 2.7-12.1 cm broad, the base cuneate to rounded and somewhat truncate, the apex acuminate to cuspidate, the upper lamina surface sparsely white velutinous, the lower surface white velutinous, the margins finely ciliate; venation weakly brochidodromous with 8-15 lateral veins per side, the midrib slightly impressed and densely white velutinous above, especially toward the base, prominently elevated and short white hirsute below, drying purplish black, the slender lateral veins elevated and short white hirsute below. Flowers solitary, pendent, terminal but appearing leaf-opposed (or rarely cauliflorous and borne on older wood), with a fruity fragranice, albeit with a slightly fetid component; pedicel 1.0-1.7 cm long, sparsely tomentellous, bearing a lanceolate-ovate to rounded bract near the base to 0.8 cm from the base, 0.50.9 cm long, 0.3-0.5 cm broad, the apex acute to obtuse, the base decurrent along the pedicel, the margins revolute. Sepals triangular, 0.7-0.8 cm long, 0.5-0.7 cm broad, the apex acute, slightly reflexed, the base truncate, tomentellous outside. Petals 6, in 2 subequal imbricate whorls, membranaceous and with venation evident in bud, becoming fleshy and lacking any evident venation at anthesis when fresh, revealing faint venation when NovoN 8: 436-440. 1998. This content downloaded from 207.46.13.128 on Wed, 07 Sep 2016 05:04:21 UTC All use subject to http://about.jstor.org/terms Volume 8, Number 4 Schatz 437 1998 New Species of Annonaceae ,,? ?r:: ~ r. r r??

Within the large palaeotropical genusPolyalthia so far five different pollen types are described (two monosulcate types, two disulcate types, and a single omniaperturate type). One of the disulcatePolyalthia types is similar to the disulcate neotropical genusSapranthus. All the newly described types differ predominantly not in exine but rather in intine characters. From this it can be concluded that seemingly “inaperturate” grains are disculcate in function, generally with two clearly recognizable germination zones, or omniaperturate, with the whole sporoderm capable of germination. The functions of the intine layers within the germination zones and within the nongerminating areas are very different and cooperate during the first germination steps in bursting the exine. It is difficult clearly to define the germination zones of pollen grains if the exine exhibits no modifications. Based on our and other results a more precise definition is suggested.