Search

SUMMARY Over 400 species of Chaetoceros Ehrenberg have been described since the genus was created in 1844, making this one of the most species-rich genera of marine planktonic diatoms. Although Chaetoceros is cosmopolitan in distribution, the temperate north Atlantic taxa are best known. Examination of material from tropical seas suggests that there are numerous Chaetoceros endemic to these biogeographic regions, which await formal description. Chaetoceros phuketensis sp. nov. is described from the Andaman Sea, in the tropical Indian Ocean. It possesses several unusual morphological characteristics not found in temperate taxa, including multiple central processes on terminal valves, vermiform chloroplasts and large size. It is most similar to Chaetoceros buceros Karsten and Chaetoceros bermejensis Hernández-Becerril, which also inhabit tropical seas. These taxa are not easily accommodated in the traditional classification scheme, which was based on turn-of-the-century knowledge of north Atlantic taxa. Approaches for classifying these unusual species include modifications of the extant scheme and creation of a new scheme based on phylogenetic principles. [ABSTRACT FROM AUTHOR]

The marine diatom flora of the tropical western Pacific island of Guam is all but unknown. Following several taxonomic/systematic papers, this floristics paper documents 179 new records of diatoms identified from light microscopy and/or scanning electron microscopy. Samples were collected from diverse habitats for several research projects in the authors’ laboratories, but the majority reported here are epiphytic, especially from pomacentrid farmer-fish territories. While many of the species are well known from other regions, some recently named, rarely seen, or poorly-described taxa include Amphora decussata Grunow;Ardissonea fulgens var. fulgens (Greville) Grunow and var. gigantea (Lobarzewsky) De Toni; Campylodiscus humilis Greville; Falcula paracelsianus Voigt; Hyalosira interrupta (Ehrenberg) Navarro; Olifantiella pilosella Riaux-Gobin; andTriceratium pulchellum (Grunow) Grunow. A preliminary checklist incorporating the new records and our previous records totals 237 taxa, which is a step towards the development of the regional flora. Many taxa remain to be identified from the documentation so far and few samples have been analyzed from other habitats such as sediments and mangroves. Only 28–42% of the species in this checklist also occurred in lists from the Society Islands, Mahé, Puerto Rico and The Bahamas—but all regions remain seriously undersampled. We do, however note some apparent differences in common and distinctive species.

Scientists building the Tree of Life face an overwhelming challenge to categorize phenotypes (e.g., anatomy, physiology) from millions of living and fossil species. This biodiversity challenge far outstrips the capacities of trained scientific experts. Here we explore whether crowdsourcing can be used to collect matrix data on a large scale with the participation of nonexpert students, or "citizen scientists." Crowdsourcing, or data collection by nonexperts, frequently via the internet, has enabled scientists to tackle some large-scale data collection challenges too massive for individuals or scientific teams alone. The quality of work by nonexpert crowds is, however, often questioned and little data have been collected on how such crowds perform on complex tasks such as phylogenetic character coding. We studied a crowd of over 600 nonexperts and found that they could use images to identify anatomical similarity (hypotheses of homology) with an average accuracy of 82% compared with scores provided by experts in the field. This performance pattern held across the Tree of Life, from protists to vertebrates. We introduce a procedure that predicts the difficulty of each character and that can be used to assign harder characters to experts and easier characters to a nonexpert crowd for scoring. We test this procedure in a controlled experiment comparing crowd scores to those of experts and show that crowds can produce matrices with over 90% of cells scored correctly while reducing the number of cells to be scored by experts by 50%. Preparation time, including image collection and processing, for a crowdsourcing experiment is significant, and does not currently save time of scientific experts overall. However, if innovations in automation or robotics can reduce such effort, then large-scale implementation of our method could greatly increase the collective scientific knowledge of species phenotypes for phylogenetic tree building. For the field of crowdsourcing, we provide a rare study with ground truth, or an experimental control that many studies lack, and contribute new methods on how to coordinate the work of experts and nonexperts. We show that there are important instances in which crowd consensus is not a good proxy for correctness., (© The Author(s) 2017. Published by Oxford University Press on behalf of the Systematic Biologists. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Competing Interests: The authors have declared that no competing interests exist.

Phylogenetic hypotheses generated from cladistic analysis of organismal and molecular data are shown to be generally congruent and/or complementary for comparisons of unicellular and colonial green algae in the Chlorophyceae. Cladistic analysis of organismal character data corroborates the alliance of colonial Stephanosphaera with unicellular Haematococcus (Haematococcaceae sensu Smith), inferred from previous studies of nuclear-encoded rRNA sequence data. The organismal data also support monophyly of the colonial Volvocaceae (sensu Smith). Alliances of other unicellular taxa, including those ascribed to the "Euchlamydomonas" Hauptgruppe (sensu Ettl), are not resolved by organismal characters principally because the structure of the data is skewed to shared ancestral characters (symplesiomorphies) and unique characters (autapomorphies) which define individual taxa only. Reanalysis of rRNA sequence data, with additional sequence data for critical taxa, does not support monophyly of the colonial Volvocaceae (sensu Smith). However, these data are weak in the support of the alternate hypothesis of nonmonophyly. In contrast, relationships among most unicellular flagellates are unambiguously resolved by the molecular data. Although the failure of the sequence data to resolve relationships among colonial flagellates appears to be due to a sampling of conservative sequences, an ancient, rapid radiation event or taxon sampling bias may also be contributing to the ambiguity problem. Results from analysis of a combined data set (organismal and molecular) are generally consistent with the inferences of the organismal character data regarding the colonial flagellates and are also consistent with the inferences of the sequence data regarding the unicellular taxa.

We have sequenced regions of the ZFY and Sox genes in the turtle Chelydra serpentina, a reptile with temperature-dependent sex determination. The ZFY gene in mammals encodes a transcription factor with multiple zinc fingers that may be involved in spermatogenesis as well as other processes. The turtle homologue, Zft, is 92% identical to the ZFY gene at the nucleotide and amino acid levels in the region of zinc fingers 7-12. There are several Sox genes in the turtle that are only 57-70% identical at the nucleotide level and about 55% identical at the amino acid level to the human sex-determining SRY gene. However, the turtle Sox genes, termed TSox, have the conserved motif called the HMG-box (for high mobility group DNA-binding protein) that defines a probable DNA-binding region, and thus are in the same gene family as the Sox genes of other organisms from Drosophila to man. One TSox sequence is identical at the amino acid level to a sequence found in birds, and is 98% identical to a sequence encoded autosomally in mouse and in man. The extent of sequence conservation among the Sox genes suggests that some of their functions may be conserved. Phylogenetic analysis of available Sox sequences including SRY (Sry) sequences suggests that there was a high degree of divergence between any possible immediate common ancestor of the turtle Sox sequences and the SRY (Sry) sequences.

Spontaneous rupture of a splenic artery aneurysm in the third trimester of pregnancy is a catastrophic event associated with a very high fetal and maternal mortality rate. There are only five reported instances of both maternal and fetal survival after spontaneous rupture of a splenic artery aneurysm. This report not only documents the sixth such case, but also recommends a different therapeutic approach for the management of such cases.