Time filter

Source Type

Los Angeles, CA, United States

Previous descriptions of members of Fabricia oregonica Banse, 1956, have distinguished it by the presence of only narrowly hooded inferior thoracic notochaetae, in contrast to the presence of pseudospatulate chaetae in median chaetigers of the type species, F. stellaris (Müller, 1774). In other respects, past descriptions of specimens to which F. oregonica refers have lacked the necessary detail to clearly determine generic placement, and the type material is in poor condition. Recently collected specimens matching earlier descriptions are used to redescribe members of the species. An exclusive sister-group relationship does not exist between F. stellaris and F. oregonica, precluding the latter species being assigned to Fabricia. Fabricia oregonica is therefore placed in a new genus, Bansella. Under the view that all taxa, whether phylogenetic or specific, are explanatory hypotheses, it is pointed out that the monotypic Bansella cannot be defined as such a hypothesis. While the International Code of Zoological Nomenclature requires that names be defined by way of 'differentiating characters,' this approach is at odds with the scientific endeavor of biological systematics to infer explanatory hypotheses, colloquially known as taxa. In addition to only having narrowly hooded inferior notochaetae, members of B. oregonica differ from F. stellaris specimens in having abdominal uncini with a much shorter manubrium. The ventral, lobe-like collar in B. oregonica specimens is also distinctly rectangular as opposed to triangular. Members of the two species are similar in that females have pigmented spermathecae in the bases of branchial lobes and spermiogenesis occurs in males in chaetigers 3-8. Copyright © 2010 · Magnolia Press.

Fitzhugh K.,Research and Collections Branch
Zootaxa | Year: 2012

Ernst Mayr's (1961, Science 131: 1501-1506) distinction between proximate and ultimate causation in biology is examined with regard to the acquisition of understanding in biological systematics. Rather than a two-part distinction, understanding in systematics is characterized by relations between three explanatory components: descriptive (observation statements)-proximate (ontogenetic hypotheses)-ultimate (e.g. specific and phylogenetic hypotheses). Initial inferential actions in each component involve reasoning to explanatory hypotheses via abductive inference, providing preliminary understanding. Testing hypotheses, to critically assess understanding, is varied. Descriptive- and proximate-level hypotheses are routinely tested, but ultimate hypotheses present inherent difficulties that impose severe limits, contrary to what is usually claimed in the systematics literature. The problem is compounded by imprecise considerations of 'evidence' and 'support.' For instance, in most cases, the 'evidence' offering 'support' for phylogenetic hypotheses, as cladograms, is nothing more than the abductive evidence (premises) used to infer those hypotheses, i.e. character data and associated phylogenetic-based theories. By definition, such evidence only offers initial, trivial understanding, whereas the pertinent evidence sought in the sciences is test evidence, which cannot be supplanted by character data. The pursuit of ultimate understanding by way of spurious procedures such as contrived testing, Bremer support, and resampling methods are discussed with regard to phylogenetic hypotheses. Copyright © 2012 Magnolia Press.

Huang D.,University of California at San Diego | Huang D.,National University of Singapore | Fitzhugh K.,Research and Collections Branch | Rouse G.W.,University of California at San Diego
Cladistics | Year: 2011

Cladistic relationships among fabriciids have to date been explored in the context of adult morphology, but resolution has been declining as more species are described. In this study, we incorporated data on the reproductive system, including features related to the male sperm and sperm storage by females, to supplement existing data on adult morphology (for a total of 50 characters). Three nuclear DNA markers (18S rDNA approximately 1800bp, the D1 region of 28S rDNA approximately 320bp, and histone H3 approximately 330bp) were sequenced from 21 species of fabriciids. We assessed the phylogeny of Fabriciidae based on an integrative analysis of these morphological and molecular characters. Our results show that, in addition to three previously recovered apomorphies for Fabriciidae (absence of ventral lips, modification of abdominal uncini to an elongate manubrium, and presence of branchial hearts), six more apomorphies associated with the reproductive system can be used to support this clade-spermiogenesis only in the thorax, spermiogenesis in large clusters with a central cytophore, single dorsal sperm duct, sperm nuclear projection, thickening of the sperm nuclear membrane and the sperm extra-axonemal sheath. The results require the erection of two new genera and two new species, which are described. © The Willi Hennig Society 2010.

Worthy T.H.,University of New South Wales | Worthy T.H.,University of Adelaide | Hand S.J.,University of New South Wales | Nguyen J.M.T.,University of New South Wales | And 6 more authors.
Journal of Vertebrate Paleontology | Year: 2010

A new species and genus of acanthisittid wren (Aves: Passeriformes: Acanthisittidae) is described from the Early Miocene (1916 Ma) St Bathans Fauna from Otago, New Zealand, based on four fossil bones. The first Tertiary fossil passerine to be described from New Zealand, it is similar in size to New Zealand's smallest extant bird, the Rifleman Acanthisitta chloris. A phylogenetic analysis of 53 osteological characters and 24 terminal taxa, including four suboscines, basal corvoids (Menuridae, Atrichornithidae, Climacteridae, Ptilonorhynchidae, Maluridae, Dasyornithidae, Acanthizidae, Pardalotidae, Meliphagidae), and all seven Recent acanthisittid species, identifies it as the sister group to Acanthisitta. This, the first phylogenetic analysis of the basal passerine groups to use morphological characters, recovers a similar pattern of relationships of basal corvoid taxa to that obtained by recent molecular studies. The analysis also suggests that Acanthisitta chloris and the new species are the most deeply nested taxa within the family, suggesting that the radiation of Recent acanthisittids originated no later than the Early Miocene. © 2010 by the Society of Vertebrate Paleontology.

Fitzhugh K.,Research and Collections Branch
Evolutionary Biology | Year: 2010

The popular defense of intelligent design/creationism (ID) theories, as well as theories in evolutionary biology, especially from the perspective that both are worthy of scientific consideration, is that empirical evidence has been presented that supports both. Both schools of thought have had a tendency to rely on the same class of evidence, namely, the observations of organisms that are in need of being explained by those theories. The result is conflation of the evidence that prompts one to infer hypotheses applying ID or evolutionary theories with the evidence that would be required to critically test those theories. Evidence is discussed in the contexts of inferring theories/hypotheses, suggesting what would be possible tests, and actual testing. These three classes of inference being abduction, deduction, and induction, respectively. Identifying these different inferential processes in evolutionary biology and ID allow for showing that the evidence to which theories and hypotheses provide understanding cannot be the same evidence supporting those theories and hypotheses. This clarification provides a strong criterion for showing the inability of an ID theory to be of utility in the ongoing process of acquiring causal understanding, that is the hallmark of science. © 2010 Springer Science+Business Media, LLC.

Discover hidden collaborations