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opencc-zeroApr 2023View details →

Morphometric and phylogeny data for: Morphology, variation, and systematics of the late Cambrian Laurentian dikelocephalid trilobite Walcottaspis vanhornei

These pages provide details of the taxa, characters and character states used in the phylogenetic analyses of Walcottaspis vanhornei (Walcott, 1914) and relatives in the accompanying paper. Phylogenetic information included here provides details of characters and taxa used for both the parsimony-based and Bayesian analyses and documents levels of support of two types (Bremer and bootstrap) for the parsimony analysis. Also included here is the result of Bayesian maximum likelihood analysis that provides further support to the results of parsimony analysis. We include bivariate plots of the variance explained by each relative warp for the sclerites analyzed and morphometric measurement error analysis.

opencc-zeroMay 2023View details →

Patterns of genetic variation and morphology support the recognition of five species in the Gaultheria leucocarpa Blume (Ericaceae) group from mainland China

Gaultheria leucocarpa and its varieties form a clade of aromatic shrubs that is widely distributed in subtropical and East Asian tropical regions. The group is taxonomically difficult and is in need of thorough taxonomic investigation. This study focused on taxonomic delimitation within the G. leucocarpa group from mainland China. Field surveys covering the distributional range of G. leucocarpa in mainland China were conducted, wherein four populations from Yunnan and one from Hunan were found bearing visibly morphological and habitat differences. A 63-species phylogenetic tree of Gaultheria based on one nuclear and three chloroplast markers that included samples from the G. leucocarpa group was reconstructed with maximum likelihood to clarify the monophyly of the G. leucocarpa group. Taxonomic relationships among populations of the G. leucocarpa group were investigated with morphology and population genetics, the latter by using two chloroplast genes and two low-copy nuclear genes. Based on the sum of morphological and genetic analyses, we described three species of Gaultheria as new to science, clarified the taxonomic status of G. leucocarpa var. pingbienensis, elevating it to the species level, and resurrected G. crenulata and treated the varieties G. leucocarpa var. crenulata, and G. leucocarpa var. yunnanensis as synonyms of this species. We provide a key to the five species now recognized, along with descriptions and photographs.

Figure 7 in Expanding knowledge of American Cerambycidae (Coleoptera): new species, new records, and morphological variations

Figure 7. Phaea quadrimaculata Wappes & Santos-Silva, 2020. (A-E) Male from Mexico, Oaxaca: (A) Dorsal habitus; (B) Ventral habitus; (C) Abdominal ventrites; (D) Lateral habitus; (E) Head, frontal view. (F) Holotype female, abdominal ventrites.

Figure 1 in Expanding knowledge of American Cerambycidae (Coleoptera): new species, new records, and morphological variations

Figure 1. Xystochroma luteotarsis sp. nov. (A-E) Holotype male: (A) Dorsal habitus; (B) Ventral habitus; (C) Lateral habitus; (D) Head, frontal view; (E) Scape. (F-G) Paratype female: (F) Dorsal habitus; (G) Ventral habitus.

Figure 4 in Expanding knowledge of American Cerambycidae (Coleoptera): new species, new records, and morphological variations

Figure 4. Rosalba strandi (Breuning, 1943). (A-D) Male, specimen 1, from Paraguay: (A) Dorsal habitus; (B) Ventral habitus; (C) Lateral habitus; (D) Head, frontal view. (E) Male from Brazil (Minas Gerais, Serra do Caraça), dorsal habitus. (F-G) Female from Paraguay: (F) Dorsal habitus; (G) Ventral habitus. (H-J) Males from Paraguay, dorsal habitus: (H) specimen 2; (I) specimen 3; (J) specimen 4.

Figure 3 in Expanding knowledge of American Cerambycidae (Coleoptera): new species, new records, and morphological variations

Figure 3. Bisaltes (Bisaltes) lateralis sp. nov., holotype female: (A) Dorsal habitus; (B) Ventral habitus; (C) Lateral habitus; (D) Head, frontal view; (E) Scape.

Figure 2 in Expanding knowledge of American Cerambycidae (Coleoptera): new species, new records, and morphological variations

Figure 2. Psyrassa spp. (A-F) P. tysoni sp. nov., holotype female: (A) Dorsal habitus; (B) Ventral habitus; (C) Lateral habitus; (D) Head, frontal view; (E) Head, lateral view; (F) Procoxal cavities. (G-J) P. pertenuis (Casey, 1924), holotype: (G) Lateroventral view; (H) Dorsal habitus; (I) Head, frontal view; (J) Partial lateral habitus. Figures G, I, and J by Eugenio H. Nearns; figure H from Lingafelter et al. (2023).

opencc-zeroJul 2023View details →

Genetic and morphological data from two bird genera (Cranioleuca and Geospiza) showing continuous variation

Extinction is a dominant force shaping patterns of biodiversity through time however its role as a catalyst of speciation has been overlooked. Here, we synthesize ideas alluded to by Darwin and others into the model of 'speciation-by-extinction' in which speciation results from the extinction of intermediate populations within a single geographically variable species. We explore the properties and distinguishing features of speciation-by-extinction with respect to other established speciation models. We demonstrate its plausibility by showing that the experimental extinction of populations within variable species can result in speciation. The prerequisites for speciation-by-extinction, geographically structured intraspecific variation and local extinction, are ubiquitous in nature, indicating that speciation-by-extinction may be a prevalent, but underappreciated, speciation mechanism.