M. Amelia Chemisquy

Phylogenetic studies favour the unification of Pennisetum, Cenchrus and Odontelytrum (Poaceae): a combined nuclear, plastid and morphological analysis, and nomenclatural combinations in Cenchrus

BACKGROUNDS AND AIMS Twenty-five genera having sterile inflorescence branches were recognized as the bristle clade within the x = 9 Paniceae (Panicoideae). Within the bristle clade, taxonomic circumscription of Cenchrus (20-25 species), Pennisetum (80-140) and the monotypic Odontelytrum is still unclear. Several criteria have been applied to characterize Cenchrus and Pennisetum, but none of these has proved satisfactory as the diagnostic characters, such as fusion of bristles in the inflorescences, show continuous variation. METHODS A phylogenetic analysis based on morphological, plastid (trnL-F, ndhF) and nuclear (knotted) data is presented for a representative species sampling of the genera. All analyses were conducted under parsimony, using heuristic searches with TBR branch swapping. Branch support was assessed with parsimony jackknifing. KEY RESULTS Based on plastid and morphological data, Pennisetum, Cenchrus and Odontelytrum were supported as a monophyletic group: the PCO clade. Only one section of Pennisetum (Brevivalvula) was supported as monophyletic. The position of P. lanatum differed among data partitions, although the combined plastid and morphology and nuclear analyses showed this species to be a member of the PCO clade. The basic chromosome number x = 9 was found to be plesiomorphic, and x = 5, 7, 8, 10 and 17 were derived states. The nuclear phylogenetic analysis revealed a reticulate pattern of relationships among Pennisetum and Cenchrus, suggesting that there are at least three different genomes. Because apomixis can be transferred among species through hybridization, its history most likely reflects crossing relationships, rather than multiple independent appearances. CONCLUSIONS Due to the consistency between the present results and different phylogenetic hypotheses (including morphological, developmental and multilocus approaches), and the high support found for the PCO clade, also including the type species of the three genera, we propose unification of Pennisetum, Cenchrus and Odontelytrum. Species of Pennisetum and Odontelytrum are here transferred into Cenchrus, which has priority. Sixty-six new combinations are made here.

Morfología craneana en tigres dientes de sable: alometría, función y filogenia

Abstract. Cranial Morphology in Sabertooth cats: allometry, function and phylogeny. Cranial morphology of felids and other sabre-toothed mammals has been studied using different approaches and methodologies. Recent studies used geometric morphometry analyses of the lateral view of the mandible and skull, and showed that “derived” sabretooth cats differ from recent felids by having a set of characters (e.g., small coronoid process, large chin and mastoid processes) associated with the presence of hypertrophied upper canines. In this study, we used geometric morphometrics to analyze the shape of the skull (dorsal and ventral views) and mandible (lateral view) in a large sample of extant felids (Felinae), extinct sabretooth felids (machairodontines), nimravids, creodonts, and the marsupial sabretooth Thylacosmilus Riggs. Results were congruent with those obtained using a lateral view of the skull: “primitive” sabretooth fell next to recent Felinae, but “derived” ones fell outside the range of Felinae, because they possessed larger mastoid process, larger and more procumbent upper incisors, and smaller temporal fossa, among other characters. However, sabretooth shared some features (e.g., large palate and canines) with larger Felinae (e.g., Panthera spp.), suggesting that they were able to hunt large mammals. The pattern of cranial variability of these groups is explained by ecological factors but also by phylogenetic constraints. The shape of the skull was correlated with the size and the length of the upper canines, two features that presented a clear correlation along the phylogeny of the group.

Molecular phylogeny of Gavilea (Chloraeinae: Orchidaceae) using plastid and nuclear markers

A phylogenetic analysis is provided for 70% of the representatives of genus Gavilea, as well as for several species of the remaining genera of subtribe Chloraeinae: Bipinnula, Chloraea and Geoblasta. Sequences from the plastid markers rpoC1, matK-trnK and atpB-rbcL and the nuclear marker ITS, were analyzed using Maximum Parsimony and Bayesian Inference. Monophyly of subtribe Chloraeinae was confirmed, as well as its position inside tribe Cranichideae. Neither Chloraea nor Bipinnula were recovered as monophyletic. Gavilea turned out polyphyletic, with Chloraeachica embedded in the genus while Gavilea supralabellata was related to Chloraea and might be a hybrid between both genera. None of the two sections of Gavilea were monophyletic, and the topologies obtained do not suggest a new division of the genus.

Phylogenetic analysis of the subtribe Chloraeinae (Orchidaceae): a preliminary approach based on three chloroplast markers.

The systematic position and relationships between some South American terrestrial orchids, such as Bipinnula Comm. ex Juss., Chloraea Lindl., Gavilea Poepp. and Geoblasta Barb. Rodr., is unclear. These four genera have been grouped in the subtribe Chloraeinae by several authors. Previous phylogenetic studies of the group have included only a few species of Chloraea and Gavilea and not of Bipinnula or Geoblasta. Relationships among these four genera were explored and the monophyly of the subtribe Chloraeinae and the genera Chloraea and Gavilea were tested in this contribution. Molecular phylogenetic analyses were conducted, using the following three chloroplast markers: the matK–trnK intron, the atpB–rbcL spacer and the rpoC1 gene. Sequences were analysed under maximum parsimony and Bayesian inference. In all the analyses, Bipinnula, Chloraea, Gavilea and Geoblasta were grouped in a clade with high support, where Bipinnula, Geoblasta and Gavilea were nested inside Chloraea. Consequently, Chloraea was paraphyletic, whereas Gavilea turned out to be monophyletic with high values of support. The other species of tribe Cranichideae appeared as sister groups of the Chloraeinae. A more exhaustive taxonomic sampling is needed to resolve the systematic placement of the subtribe Chloraeinae and the internal relationships between the genera and species that form it.

The Lucilia group (Asteraceae, Gnaphalieae): phylogenetic and taxonomic considerations based on molecular and morphological evidence

The Lucilia group sensu Anderberg and Freire comprises nine South American genera: Belloa, Berroa, Chevreulia, Cuatrecasasiella, Facelis, Gamochaetopsis, Jalcophila, Lucilia and Luciliocline. The aims of this contribution were, using DNA sequences from plastid (rpl32-trnL, trnL-F) and nuclear (ITS and ETS) markers, together with morphological characters, to test the monophyly of the Lucilia group and provide new insight into generic circumscriptions. Our studies, including a broad taxon sampling of Gnaphalieae species, suggest that the Lucilia group is paraphyletic, since Antennaria, Chionolaena, Gamochaeta, Loricaria, Micropsis, Mniodes and Stuckertiella are all nested within the Lucilia group. Morphology and molecular analyses combined showed that the traditional generic circumscription of most of the genera (e.g., Berroa, Chevreulia, Chionolaena, Cuatrecasasiella, Facelis, Jalcophila and Micropsis) correlates with the inferred phylogenetic relationships. Conversely, Lucilia and Luciliocline are non-monophyletic. Lucilia is nested in a clade with Berroa, Facelis and Micropsis. Luciliocline is strongly embedded within the clade Belloa pp + Mniodes. Our results are consistent with Dillon’s study that considered Belloa as a montotypic genus (B. chilensis). Luciliocline and the remaining species of Belloa are accommodated in the genus Mniodes, and the necessary combinations are proposed for the expanded Mniodes. All the analyses showed that the monotypic genera Stuckertiella and Gamochaetopsis are in a well-supported clade nested within Gamochaeta, which implies that taxonomic changes are required also for these genera. Internal relationships in the group and the key morphological characters used in the taxonomy of the group, as well as incongruences found between morphological and molecular analyses, are discussed.

Peramorphic males and extreme sexual dimorphism in Monodelphis dimidiata (Didelphidae)

The southern short-tailed opossum, Monodelphisdimidiata, is a species known not only for its semelparous life cycle, but also for the extreme sexual dimorphism of adults, where males are not only larger, but also have distinctive morphological characters in their skull. Using geometric morphometrics and a suite of statistical tests, I analyzed the postweaning ontogenetic development of this species in order to evaluate the age-class where sexual dimorphism becomes significant and the amount of change exhibited by both sexes. My results showed that M.dimidiata partly follows the ontogenetic pattern described for didelphids by previous authors. The character that escapes the general pattern is rostral length, which becomes shorter instead of lengthening throughout the development. This change could be related to an increment in the bite force in the anterior part of the dentition. The amount of sexual dimorphism found for this species is larger than the reported previously for other American marsupials, and I also found a higher rate of growth in males at the attaining of sexual maturity. Based on my results and the information available for other didelphids, I can suggest that M.dimidiata males undergo through a process of hypermorphosis, resulting in a peramorphic condition. It is possible that the extreme sexual dimorphism present in this species is related to reproductive success, specially taking into account their semelparous life cycle.

Gavilea gladysiae (Chloraeeae: Orchidaceae), a new orchid from southern Argentina and Chile

A new species, Gavilea gladysiae, is described and illustrated. This rare species inhabits the humid forests of Santa Cruz (southern Argentina) and the Magellan region (southern Chile). This species has been mistakenly identified as Gavilea kingii in herbarium collections and previous floristic works.

Evolution of the Carnassial in Living Mammalian Carnivores (Carnivora, Didelphimorphia, Dasyuromorphia): Diet, Phylogeny, and Allometry

Different living mammals have developed a carnivorous habit (e.g., Carnivora, Dasyuridae, Thylacinidae, some Didelphidae). They exhibit different specializations for carnivory; however, they share some characters such as a carnassial molar. Previous studies have correlated the shape of molars with diet using morphometric indices or surface scans. In this work, we used 3D geometric morphometrics to explore the shape of the lower carnassials of 235 specimens corresponding to 71 extant species of Carnivora and six extant species of Marsupialia, both Didelphimorphia and Dasyuromorphia. We statistically estimated the effect of size, diet, and phylogeny on molar shape. All the analyses indicated a higher correlation between diet and molar shape, and a better correlation between molar shape and the position of each species on the phylogeny. Therefore, if we take into account the phylogenetic pattern, we can use molar morphology to infer diet of fossil species. Finally, this work evaluates for the first time, in a quantitative way, which of the lower molars of the Metatheria (m3 or m4) is the best analogue to the m1 of Carnivora; our results indicated the m4 is the best analogue.