Light and electron microscope observations on Nephroselmis astigmatica sp. nov. (Prasinophyceae)

Nephroselmis astigmatica sp. nov. is described based on light and electron microscope observations of cultured material, originally collected and isolated from the Natal South Coast, Republic of South Africa. It is characterized by (1) large cell size, (2) absence of a stigma, (3) markedly differentiated anterior part of the cell, (4) possessing two types of flagellar scales in addition to hair scales, (5) possessing four types of body scales and (6) the presence of characteristic pit scales in the flagellar pit. Scale morphology was compared with previously described species, and the morphology of spiny (or stellate) body scales thought to be one of the most useful diagnostic characters in delineating species within the genus. The origin of pit scales is discussed and a similar origin for the third layer of flagellar scales of the type species, N. olivacea Stein is suggested. N. astigmatica shares many ultrastructural features with the type species, including the microtubular flagellar root system consisting of three different roots, one of which is multilayered. The validity of this root system as a generic character is suggested.     

Ultrastructure of the flagellar apparatus inPleurochrysis (classPrymnesiophyceae)

Summary The ultrastructure of the flagellar apparatus of aPleurochrysis, a coccolithophorid was studied in detail. Three major fibrous connecting bands and several accessory fibrous bands link the basal bodies, haptonema and microtubular flagellar roots. The asymmetrical flagellar root system is composed of three different microtubular roots (referred to here as roots 1,2, and 3) and a fibrous root. Root 1, associated with one of the basal bodies, is of the compound type, constructed of two sets of microtubules,viz. a broad sheet consisting of up to twenty closely aligned microtubules, and a secondary bundle made up of 100–200 microtubules which arises at right angles to the former. A thin electron-dense plate occurs on the surface of the microtubular sheet opposite the secondary bundle. The fibrous root arises from the same basal body and passes along the plasmalemma together with the microtubular sheet of root 1. Root 2 is also of the compound type and arises from one of the major connecting bands (called a distal band) as a four-stranded microtubular root and extends in the opposite direction to the haptonema. From this stranded root a secondary bundle of microtubules arises at approximately right angle. Root 3 is a more simple type, composed of at least six microtubules which are associated with the basal body. The flagellar transition region was found to be unusual for the classPrymnesiophyceae. The phylogenetic significance of the flagellar apparatus in thePrymnesiophyceae is discussed.     

THE FINE STRUCTURE OF HYMENOMONAS (CRICOSPHAERA) CARTERAE. II. OBSERVATIONS ON SCALE AND COCCOLITH PRODUCTION

The fine structure of the marine coccolithophorid Hymenomonas (Cricosphaera) carterae (Braarud & Fagerland) Manton & Peterfi is reported. Details of the formation of the circular organic body scales are presented. Their formation is shown to be closely linked with the presence of tubules found within the Golgi cisternae. The details of coccolith production are also discussed. The formation of the organic matrix scale appears to be associated with a densely staining organelle, the intracellular coccolith pre-cursor. The precise mechanisms involved in the mineralization of the organic matrix scale is not known but 2 possibilities are discussed. The production of coccoliths in H. carterae is compared with coccolith production in other coccolithophorids that have been investigated finestructurally.     

Investigating Support for Management of the Pet Trade Invasion Risk

The non-native pet trade contributes directly to species invasions, thereby threatening wildlife. Biological invasions influence environmental change, resulting in species extinctions and biodiversity loss. To mitigate the pet trade invasion risk, interventions are required to prevent trade in non-native animals with high invasion potential, impulse or ill-informed purchases of non-native pets by individuals who may release these animals, and the deliberate release of non-native animals by pet owners. Interventions are also required to prevent the establishment of non-native animals that have been released by pet owners (e.g., euthanasia). The successful implementation of these interventions depends on the support of pet owners and the public in the form of political support for, and compliance with, interventions. In 2017–2018, using both mail and online surveys, we measured the support of 1,171 members of the public and 550 owners of non-native pets in Florida, USA, for 7 different interventions to mitigate the pet trade invasion risk, and we investigated determinants of this support. We found that individuals' support for interventions depended on their concern related to the invasion risks associated with the pet trade, trust in government to manage the pet trade, perceptions of how effective interventions would be in mitigating the pet trade invasion risk, and demographic characteristics. Support for interventions differed across pet owners and the public. Educating pet owners about the traits and cost of care for non-native animals and providing them with options to relinquish unwanted pets may reduce the pet trade invasion risk. Engaging the pet trade in the design of interventions to mitigate invasion risks is likely important to attain voluntary compliance with these interventions. The effectiveness of interventions also depends on enforcement by agencies. Implementing interventions that effectively reduce the pet trade invasion risk is important to protect native and endangered wildlife. © 2020 The Wildlife Society.     

Stocking rate and organic waste type affect development of three Chrysomya species and Lucilia sericata (Diptera: Calliphoridae): Implications for bioconversion

Fly larvae can be used effectively to reduce various organic waste types and produce value-added products, including protein as an ingredient in livestock feeds and oil for biodiesel production. However, fly development on different waste types may cause differences in growth rate and the body composition, which can further be influenced by fly species and their stocking rate. This study explored the impact of different waste types (kitchen waste, abattoir waste and swine manure) and larval stocking rate on growth and body composition of four blowfly species, Chrysomya chloropyga (Wiedemann), Chrysomya megacephala (Fabricius), Chrysomya putoria (Wiedemann) and Lucilia sericata (Meigen). First-instar larvae (20, 50 or 100), less than 3 hr old, were placed on 100 g of each waste type. Pre-pupal mass at commencement of post-feeding larval dispersal, time to onset of dispersal, survival and nutrient reserves were determined for each species, stocking rate and waste type. Our results revealed that larvae fed kitchen and abattoir waste had significantly higher dry mass, crude protein and lipid content compared with those fed swine manure. Higher survival rate was observed with increasing larval stocking rate. We provide important information to guide the mass production of high-quality nutrient-rich larvae and recommend C. putoria, which is versatile and effective on a range of waste products, as well as high in protein and lipids. The implications for waste management are discussed.     

The Mitochondrial Genomes of Nuttalliella namaqua (Ixodoidea: Nuttalliellidae) and Argas africolumbae (Ixodoidae: Argasidae): Estimation of Divergence Dates for the Major Tick Lineages and Reconstruction of Ancestral Blood-Feeding Characters

Ixodida are composed of hard (Ixodidae), soft (Argasidae) and the monotypic Nuttalliellidae (Nuttalliella namaqua) tick families. Nuclear 18S rRNA analysis suggested that N. namaqua was the closest extant relative to the last common ancestral tick lineage. The mitochondrial genomes of N. namaqua and Argas africolumbae were determined using next generation sequencing and de novo assembly to investigate this further. The latter was included since previous estimates on the divergence times of argasids lacked data for this major genus. Mitochondrial gene order for both was identical to that of the Argasidae and Prostriata. Bayesian analysis of the COI, Cytb, ND1, ND2 and ND4 genes confirmed the monophyly of ticks, the basal position of N. namaqua to the other tick families and the accepted systematic relationships of the other tick genera. Molecular clock estimates were derived for the divergence of the major tick lineages and supported previous estimates on the origins of ticks in the Carboniferous. N. namaqua larvae fed successfully on lizards and mice in a prolonged manner similar to many argasids and all ixodids. Excess blood meal-derived water was secreted via the salivary glands, similar to ixodids. We propose that this prolonged larval feeding style eventually gave rise to the long feeding periods that typify the single larval, nymphal and adult stages of ixodid ticks and the associated secretion of water via the salivary glands. Ancestral reconstruction of characters involved in blood-feeding indicates that most of the characteristics unique to either hard or soft tick families were present in the ancestral tick lineage.