List of Titles

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Phylogeny, biogeography and classification of the snake superfamily Elapoidea a rapid radiation in the late Eocene

- Kelly, Christopher M R, Barker, Nigel P, Villet, Martin H, Broadley, Donald G

Authors: Kelly, Christopher M R , Barker, Nigel P , Villet, Martin H , Broadley, Donald G
Date: 2009
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/442267 , vital:73971 , https://doi.org/10.1111/j.1096-0031.2008.00237.x
Description: The snake superfamily Elapoidea presents one of the most intransigent problems in systematics of the Caenophidia. Its monophyly is undisputed and several cohesive constituent lineages have been identified (including the diverse and clinically important family Elapidae), but its basal phylogenetic structure is obscure. We investigate phylogenetic relationships and spatial and temporal history of the Elapoidea using 94 caenophidian species and approximately 2300–4300 bases of DNA sequence from one nuclear and four mitochondrial genes. Phylogenetic reconstruction was conducted in a parametric framework using complex models of sequence evolution. We employed Bayesian relaxed clocks and Penalized Likelihood with rate smoothing to date the phylogeny, in conjunction with seven fossil calibration constraints. Elapoid biogeography was investigated using maximum likelihood and maximum parsimony methods. Resolution was poor for early relationships in the Elapoidea and in Elapidae and our results imply rapid basal diversification in both clades, in the late Eocene of Africa (Elapoidea) and the mid‐Oligocene of the Oriental region (Elapidae). We identify the major elapoid and elapid lineages, present a phylogenetic classification system for the superfamily (excluding Elapidae), and combine our phylogenetic, temporal and biogeographic results to provide an account of elapoid evolution in light of current palaeontological data and palaeogeographic models.
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Date Issued: 2009

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Predicting geographic distribution of seven blowfly species (Diptera: Calliphoridae) in South Africa

- Richards, Cameron S, Williams, Kirstin A, Villet, Martin H

Authors: Richards, Cameron S , Williams, Kirstin A , Villet, Martin H
Date: 2009
Language: English
Type: text , Article
Identifier: vital:6854 , http://hdl.handle.net/10962/d1011135
Description: The predicted geographic distributions of seven forensically important blowfly species are modelled using the computer program Maxent, based on selected climatic variables for South Africa, a country with large climatic and environmental gradients. It is shown that although temperature was hypothesized to most influence the distributions of these ectotherms, moisture, and particularly humidity, was in fact usually paramount. Chrysomya albiceps (Wiedemann) and C. marginalis (Robineau-Desvoidy) had the most widespread geographic and climatic distribution, while the forest-associated C. inclinata(Walker) was the least widespread. Chrysomya putoria (Wiedemann) and C. megacephala (Fabricius) had very similar predicted distributions that were restricted mainly to Limpopo, Mpumalanga, KwaZulu-Natal and the coast of the Eastern Cape. Chrysomya chloropyga (Wiedemann) and Calliphora croceipalpis (Jaennicke) were the only species predicted to occur at high altitudes. Blowfly distributions restricted to part of the map area were predicted better than those that were more widespread in the region, presumably because species with extremely widespread distributions in a study area occupy nearly the whole range of variation of most predictor variables, leaving little variation with which themaximumentropy modelling method can discriminate between presence and absence of the organism.
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Date Issued: 2009

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Thermal ecophysiology of seven carrion‐feeding blowflies in Southern Africa

- Richards, Cameron S, Price, Benjamin W, Villet, Martin H

Authors: Richards, Cameron S , Price, Benjamin W , Villet, Martin H
Date: 2009
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/442384 , vital:73980 , https://doi.org/10.1111/j.1570-7458.2009.00824.x
Description: A variety of temperature thresholds for larvae, pupae, and adults of seven African species of carrion‐feeding blowflies (Diptera: Calliphoridae) was measured and compared to understand their basic thermal biology and the influence of temperature on their behaviour. Calliphoraácroceipalpis (Jaennicke) had consistently lower temperature thresholds than all other species tested for all larval (42.9á░C), pupal (16.6á░C), and adult (45.6á░C) stages. Larvae (50.1á░C) and adults (53.4á░C) of Chrysomyaámarginalis (Robineau‐Desvoidy) had higher upper lethal temperature thresholds than all other species and weighed more than all other species. Pupae and adults of both Chrysomyaáalbiceps (Wiedemann) and Luciliaásericata (Meigen) had similar temperature thresholds, whereas Chrysomyaáputoria (Wiedemann), Chrysomyaáchloropyga (Wiedemann), and Chrysomyaámegacephala (Fabricius) had inconsistent rank temperature thresholds between the larval, pupal, and adult stages. With a few minor exceptions, the nervous activity, muscle activity, and death thresholds in female adult flies responded at higher temperatures than conspecific male flies for all species tested. Similarly, female adult flies weighed consistently more than conspecific male flies for all species tested, except Ca.ácroceipalpis. These data suggest that there is a phylogenetic component to the thermal biology of blowflies, because Ca.ácroceipalpis belongs to a primarily Holarctic genus and shows adaptation to that climate even though it inhabits Africa. Comparisons between these temperature thresholds and the distributions of blowfly species present on three rhinoceros carcasses suggest that blowfly larvae with high upper lethal temperature thresholds (particularly C.ámarginalis) dominate in interspecific competition on the carcass by raising the temperature of the amassed maggots above the thresholds of other carrion‐feeding blowflies, through metabolically generated heat.
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Date Issued: 2009

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A global study of forensically significant calliphorids: implications for identification

- Harvey, M L, Gaudieri, S, Villet, Martin H, Dadour, I R

Authors: Harvey, M L , Gaudieri, S , Villet, Martin H , Dadour, I R
Date: 2008
Language: English
Type: text , Article
Identifier: vital:6863 , http://hdl.handle.net/10962/d1011156
Description: A proliferation of molecular studies of the forensically significant Calliphoridae in the last decade has seen molecule-based identification of immature and damaged specimens become a routine complement to traditional morphological identification as a preliminary to the accurate estimation of post-mortem intervals (PMI), which depends on the use of species-specific developmental data. Published molecular studies have tended to focus on generating data for geographically localised communities of species of importance, which has limited the consideration of intraspecific variation in species of global distribution. This study used phylogenetic analysis to assess the species status of 27 forensically important calliphorid species based on 1167 base pairs of the COI gene of 119 specimens from 22 countries, and confirmed the utility of the COI gene in identifying most species. The species Lucilia cuprina, Chrysomya megacephala, Ch. saffranea, Ch. albifrontalis and Calliphora stygia were unable to be monophyletically resolved based on these data. Identification of phylogenetically young species will require a faster-evolving molecular marker, but most species could be unambiguously characterised by sampling relatively few conspecific individuals if they were from distant localities. Intraspecific geographical variation was observed within Ch. rufifacies and L. cuprina, and is discussed with reference to unrecognised species.
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Date Issued: 2008

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A survey of fruit-feeding insects and their parasitoids occurring on wild olives, Olea europaea ssp. cuspidata, in the Eastern Cape of South Africa

- Mkize, Nolwazi, Hoelmer, Kim A, Villet, Martin H

Authors: Mkize, Nolwazi , Hoelmer, Kim A , Villet, Martin H
Date: 2008
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/441694 , vital:73907 , https://doi.org/10.1080/09583150802450154
Description: Fruits of wild olives, Olea europaea ssp. cuspidata (Wall. ex G. Don) Cif., were collected in the Eastern Cape, South Africa, during 2003–2005 to quantify levels of fruit-infesting pests and their parasitoids. Two species of Tephritidae, Bactrocera oleae (Rossi) and B. biguttula (Bezzi), were the most abundant insects recovered and were reared from most samples. Fruit infestation rates by the Bactrocera spp. were generally below 8% and over half of the infestations were under 1%. When parasitism occurred in samples with flies, levels ranged from 7 to 83%. Several species of opiine braconid wasps, Psyttalia concolor (Szépligeti), Psyttalia lounsburyi (Silvestri), and Utetes africanus (Szépligeti) and one braconine wasp, Bracon celer Szépligeti, were reared from fruits containing B. oleae and/or B. biguttula. Chalcidoid parasitoids and seed wasps included seven species of Eurytomidae (Eurytoma oleae, Eurytoma sp., and Sycophila sp.), Ormyridae (Ormyrus sp.), Torymidae (Megastigmus sp.), and Eupelmidae (Eupelmus afer and E. spermophilus). One species of moth, Palpita unionalis (Hübner) (Crambidae), was recovered in very low numbers and without parasitoids. The survey results indicate that fruit flies might not become economic pests of the nascent commercial olive industry in the Eastern Cape, and the small numbers present may be controlled to a considerable level by natural enemies.
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Date Issued: 2008

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Baited traps may be an alternative to conventional pesticides in the integrated crop management of chicory (Compositae) in South Africa

- Midgley, John M, Hill, Martin P, Villet, Martin H

Authors: Midgley, John M , Hill, Martin P , Villet, Martin H
Date: 2008
Language: English
Type: Article
Identifier: vital:6858 , http://hdl.handle.net/10962/d1011141 , http://dx.doi.org/10.1603/0022-0493(2008)101[99:BTMBAA]2.0.CO;2 , https://orcid.org/0000-0003-0579-5298
Description: Chicory, Chicorium intybus L. (Compositae), is a major field crop in the Eastern Cape Province of South Africa. Several pests feed on the leaves of the plant, resulting in reduced yield. The most important of these are the noctuid moths Helicoverpa armigera (Hübner), Chrysodeixis acuta (Walker), and Trichoplusia orichalcea (F.). The use of attract-and-kill traps offers an alternative to broad-based insecticides in the control of these species. Three fields were treated with normal insecticides and three fields with yellow-baited traps. Eight additional traps were placed in each field, with half of the traps containing the insecticide 2,2-dichlorovinyl dimethyl phosphate (dichlorvos) and half without dichlorvos; and half yellow and half green. Total moth numbers and nonphytophage diversity were measured from these eight traps. Although no differences in H. armigera or T. orichalcea catches were observed between insecticide- and trap-treated fields, numbers of C. acuta and the total number of moths were significantly higher in insecticide-treated fields. Yellow traps containing dichlorvos contained more moths than yellow traps without dichlorvos, or green traps with dichlorvos, or green traps without dichlorvos; but they also contained more nonphytophagous insects. Yellow traps also enhanced the catches of thrips on card traps associated with them. These results offer an opportunity for the South African chicory industry to reduce pesticide applications and thus mitigate environmental impacts.
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Date Issued: 2008

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Editorial: authorship and responsibility [African Entomology]

- Villet, Martin H

Authors: Villet, Martin H
Date: 2008
Language: English
Type: Article
Identifier: vital:6851 , http://hdl.handle.net/10962/d1011132
Description: Editorial service is a privilege in many senses: editors have a much broader view of disciplinary practices than most of their colleagues; they see work from more institutions; and are privy to manuscripts in all states of fitness for publication. The spectrum of practice is eye-opening, and editors are placed in a position of stewardship, and often mentorship, that inevitably focuses attention on quality assurance and ethics (Lawrence 2003; Bulger 2004; Grieger 2005; Graf et al. 2007). Recently, the Committee on Scholarly Publishing in South Africa, a body within the Academy of Science of South Africa (ASSAf), has drafted Guidelines for best practice in editorial discretion and peer review for South African scholarly journals to assist editors.
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Date Issued: 2008

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Estimating the age of immature Chrysomya albiceps (Diptera: Calliphoridae), correcting for temperature and geographical latitude

- Richards, Cameron S, Paterson, Iain D, Villet, Martin H

Authors: Richards, Cameron S , Paterson, Iain D , Villet, Martin H
Date: 2008
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/442129 , vital:73961 , https://doi.org/10.1007/s00414-007-0201-7
Description: Developmental curves for Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae) were established at 13 different constant temperatures using developmental landmarks and length as measures of age. The thermal summation constants (K) and developmental zeros (D 0) were calculated for five developmental landmarks using the method described by Ikemoto and Takai (Environ Entomol 29:671–682, 2000). Comparison with the K and D 0 values of our findings to those of three previously published studies of C. albiceps suggests that K is directly proportional to geographic latitude, and D 0 is inversely proportional to both K and geographic latitude. Body size and developmental landmarks have a complex relationship because of trade-offs between mortality risk and female fecundity (as measured by body size) at non-optimal temperatures. This relationship can be summarized using superimposed isomorphen and isomegalen diagrams, which can then be used to make forensic estimates of postmortem intervals from larval body lengths. Finally, we recommend that future studies providing data for precise forensic estimates of postmortem intervals should use a relative temporal precision of about 10% of the total duration being measured. For many blowflies, this translates into a sampling interval of approximately every 2 h before hatching, 3 h before first ecdysis and 6 h before second ecdysis.
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Date Issued: 2008

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Factors affecting accuracy and precision of thermal summation models of insect development used to estimate post-mortem intervals

- Richards, Cameron S, Villet, Martin H

Authors: Richards, Cameron S , Villet, Martin H
Date: 2008
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/442142 , vital:73962 , https://doi.org/10.1007/s00414-008-0243-5
Description: This paper investigates the effects that different summary statistics (minimum, median, mean, or maximum), temporal sampling resolutions (duration between sampling events), and sample sizes (number of individuals sampled per sampling event) had on the accuracy and precision of the regression coefficients of a typical thermal summation model used to calculate minimum post-mortem interval (PMI). No significant differences were found in the values of the developmental constants calculated from different summary statistics of the duration of development. Sample size was found to affect the precision of measurement of the duration of development but had little overall influence on thermal summation constant (K) and developmental threshold (D 0) calculations (and therefore, subsequent PMI estimates), but temporal sampling resolution had a direct influence on the accuracy of K and D 0 calculations. These data suggest that when numbers of experimental maggots are limited, it is more important to sample more frequently using smaller sample sizes than to sample less frequently with large sample sizes. Furthermore, we suggest that the median is the most representative summary measure of the duration of development and should be used preferentially.
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Date Issued: 2008

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Forensic Entomology: An Introduction, D.E. Gennard book: review

- Villet, Martin H, Richards, Cameron S

Authors: Villet, Martin H , Richards, Cameron S
Date: 2008
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/451690 , vital:75070 , https://hdl.handle.net/10520/EJC32766
Description: Since the publication of Smith's (1986) "A manual of forensic entomology", there have been a series of useful texts in forensic entomology, some written as authoritative resources (Byrd and Castner 2001; Greenberg and Kunish 2002; Wyss and Cherix 2006) and others as training manuals (Catts and Haskell 1990). Dorothy Gennard's contribution is a bit of both, being the first text written primarily as a broad introduction to medico-criminal forensic entomology for specialised undergraduate classes.
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Date Issued: 2008

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Identifying flies used for maggot debridement therapy

- Williams, Kirstin A, Cronje, F, Avenant, L, Villet, Martin H

Authors: Williams, Kirstin A , Cronje, F , Avenant, L , Villet, Martin H
Date: 2008
Language: English
Type: Article
Identifier: vital:6852 , http://hdl.handle.net/10962/d1011133
Description: To the Editor: The use of maggots to clean necrotic wounds, known as maggot debridement therapy (MDT), has long been known to the scientific world. Its use has been recorded since the 1500s when soldiers’ wounds were often infested with maggots. Napoleon’s surgeon, Baron Dominic Larrey, reported that wounds that were infested with maggots appeared to heal faster than those without maggots.1 William Baer is considered to be the founder of modern MDT. While treating soldiers in World War I, he noted the good condition of wounds that had been infested with maggots, and was the first doctor on record to experiment with the use of maggots in treating infections.1 MDT even featured in the recent version of the film ‘Spartacus’. Various species of flies have been used for MDT,1 the most commonly used being Lucilia sericata, a greenbottle blowfly (Figs 1 and 2). This fly is closely related to another greenbottle, L. cuprina, but L. cuprina feeds on live as well as necrotic tissue, which is undesirable in MDT. L. cuprina is commonly named the ‘sheep blowfly’ because it is responsible for fly-strike in sheep, a form of massive, usually rectal myiasis that can kill sheep. A recent article2 suggested that L. cuprina was being used successfully for MDT at the Eugene Marais Hospital Wound Care Centre (EMHWCC). As this would be inconsistent with international experience in MDT and at odds with the usual biology of L. cuprina, it was decided to check the identity of these flies.
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Date Issued: 2008

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The snake family Psammophiidae (Reptilia: Serpentes): phylogenetics and species delimitation in the African sand snakes (Psammophis Boie, 1825) and allied genera

- Kelly, Christopher M R, Barker, Nigel P, Villet, Martin H, Broadley, Donald G, Branch, William R

Authors: Kelly, Christopher M R , Barker, Nigel P , Villet, Martin H , Broadley, Donald G , Branch, William R
Date: 2008
Language: English
Type: Article
Identifier: vital:6522 , http://hdl.handle.net/10962/d1005953
Description: This study constitutes the first evolutionary investigation of the snake family Psammophiidae—the most widespread, most clearly defined, yet perhaps the taxonomically most problematic of Africa's familylevel snake lineages. Little is known of psammophiid evolutionary relationships, and the type genus Psammophis is one of the largest and taxonomically most complex of the African snake genera. Our aims were to reconstruct psammophiid phylogenetic relationships and to improve characterisation of species boundaries in problematic Psammophis species complexes. We used approximately 2500 bases of DNA sequence from the mitochondrial and nuclear genomes, and 114 terminals covering all psammophiid genera and incorporating approximately 75% of recognised species and subspecies. Phylogenetic reconstructions were conducted primarily in a Bayesian framework and we used the Wiens/Penkrot protocol to aid species delimitation. Rhamphiophis is diphyletic, with Rhamphiophis acutus emerging sister to Psammophylax. Consequently we transfer the three subspecies of Rhamphiophis acutus to the genus Psammophylax. The monotypic genus Dipsina is sister to Psammophis. The two species of Dromophis occupy divergent positions deeply nested within Psammophis, and we therefore relegate Dromophis to the synonymy of Psammophis. Our results allow division of the taxonomically problematic Psammophis 'sibilans' species complex into two monophyletic entities, provisionally named the 'phillipsii' and 'subtaeniatus' complexes. Within these two clades we found support for the status of many existing species, but not for a distinction between P.p. phillipsii and P. mossambicus. Additionally, P. cf. phillipsii occidentalis deserves species status as the sister taxon of P. brevirostris.
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Date Issued: 2008

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An inexpensive geometrical micrometer for measuring small, live insects quickly without harming them

- Villet, Martin H

Authors: Villet, Martin H
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/441860 , vital:73928 , https://doi.org/10.1111/j.1570-7458.2006.00520.x
Description: The article discusses the technical note for the journal" Entomologia Experimentalis et Applicata," in the first quarter of 2007 issue. The author provides information about an inexpensive geometrical micrometer for measuring small, live insects rapidly and accurately without causing harm to the organism. The method he applied for making the measurements is related to the wedge micrometer as described by the scientist SD Porter in 1983.
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Date Issued: 2007

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Karyology of three evolutionarily hexaploid southern African species of yellowfish, Labeobarbus Rüppel, 1836 (Cyprinidae)

- Naran, Daksha, Skelton, Paul H, Villet, Martin H

Authors: Naran, Daksha , Skelton, Paul H , Villet, Martin H
Date: 2007
Language: English
Type: Article
Identifier: vital:6855 , http://hdl.handle.net/10962/d1011138 , http://dx.doi.org/10.3377/1562-7020(2007)42[254:KOTEHS]2.0.CO;2
Description: The karyotypes of three species of yellowfish, namely Labeobarbus marequensis (A. Smith, 1841), L. capensis (A. Smith, 1841) and L. polylepis (Boulenger, 1907), were examined by Giemsa staining using an approach improved for the description of high chromosome numbers. In each case, 2n = 150; no heteromorphic chromosomes were detected; chromosomes in all morphological categories ranged smoothly from large to small, with no distinctly large submetacentric pairs; and metacentric chromosomes showed little variation in size. Labeobarbus marequensis had 26 metacentric (m), 44 submetacentric (sm), 42 subtelocentric (st) and 38 acrocentric (a) chromosomes and a fundamental number (FN) of 262; L. capensis had 16 m, 58 sm, 42 st and 34 a chromosomes and FN = 266; and L. polylepis had 18 m, 60 sm, 42 st and 30 a chromosomes and FN = 270. These results, combined with published literature, imply that Labeobarbus Rüppel, 1836 is an evolutionarily hexaploid African lineage and support its removal from synonymy with the evolutionarily tetraploid Asian genus Tor Gray, 1834. A review of fundamental numbers for conspecific Labeobarbus species examined in different studies implicated karyological technique as a confounding factor in assessing details of karyotypes, leading to recommendations for future karyological studies of barbine fishes. Potential synapomorphies are pointed out in karyological characters of species within Labeobarbus.
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Date Issued: 2007

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Patterns and processes underlying evolutionary significant units in the Platypleura stridula L. species complex (Hemiptera: Cicadidae) in the Cape Floristic Region, South Africa

- Price, Benjamin W, Barker, Nigel P, Villet, Martin H

Authors: Price, Benjamin W , Barker, Nigel P , Villet, Martin H
Date: 2007
Language: English
Type: Article
Identifier: vital:6964 , http://hdl.handle.net/10962/d1012027
Description: Cicadas have been shown to be useful organisms for examining the effects of distribution, plant association and geographical barriers on gene flow between populations. The cicadas of the Platypleura stridula species complex are restricted to the biologically diverse Cape Floristic Region (CFR) of South Africa. They are thus an excellent study group for elucidating the mechanisms by which hemipteran diversity is generated and maintained in the CFR. Phylogeographical analysis of this species complex using mitochondrial DNA Cytochrome Oxidase I (COI) and ribosomal 16S sequence data, coupled with preliminary morphological and acoustic data, resolves six clades, each of which has specific host-plant associations and distinct geographical ranges. The phylogeographical structure implies simultaneous or near-simultaneous radiation events, coupled with shifts in host-plant associations. When calibrated using published COI and 16S substitution rates typical for related insects, these lineages date back to the late Pliocene - early Pleistocene, coincident with vegetation change, altered drainage patterns and accelerated erosion in response to neotectonic crustal uplift and cyclic Pleistocene climate change, and glaciation-associated changes in climate and sea level.
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Date Issued: 2007

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Report of the multidisciplinary investigation of differentiation and potential hybridisation between two Yellowfish species Labeobarbus Kimberleyensis and L. Aeneus from the Orange-Vaal system

- Bloomer, Paulette, Villet, Martin H, Bills, Ian R, Van der Bank, F Herman, Jones, Nick, Walsh, Gina

Authors: Bloomer, Paulette , Villet, Martin H , Bills, Ian R , Van der Bank, F Herman , Jones, Nick , Walsh, Gina
Date: 2007
Language: English
Type: Report
Identifier: vital:7162 , http://hdl.handle.net/10962/d1011937
Description: From the executive summary]: The relationships within and between two yellowfish species, Labeobarbus aeneus (smallmouth yellowfish) and L. kimberleyensis (largemouth yellowfish) from the Orange-Vaal system were investigated through three independently conducted studies of the same material collected from the Sak River (the type locality of L. aeneus), the upper Orange River at Aliwal North and the lower Orange River at Pella and Onseepkans.
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Date Issued: 2007

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Spermiogenesis in three species of cicadas (Hemiptera: Cicadidae)

- Chawanji, A S, Hodgson, Alan N, Villet, Martin H, Sanborn, Allen F, Phillips, Polly K F

Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H , Sanborn, Allen F , Phillips, Polly K F
Date: 2007
Language: English
Type: Article
Identifier: vital:6865 , http://hdl.handle.net/10962/d1011207
Description: Spermiogenesis in three species of cicadas representing one cicadettine (Monomatapa matoposa Boulard) and two cicadines (Diceroprocta biconica [Walker] and Kongota punctigera [Walker]) was investigated by light and electron microscopy. Although spermiogenesis was occurring in the testis of adult males of all species, earlier spermiogenic stages were observed in D. biconica only. While spermiogenesis was similar to that described for other insects, some differences were noted. For example granular material did not assemble around the centriole to form a centriolar adjunct but did accumulate in the cytoplasm of early spermatids adjacent to a region of the nuclear membrane where nuclear pores were aggregated. In late spermatids this material accumulated anterior to the mitochondrial derivatives in a developing postero-lateral nuclear groove. While this material has been named the ‘centriolar adjunct’ by previous authors, its formation away from the centriole raises questions about its true identity. Second, during acrosome maturation an ante-acrosomal region of cytoplasm develops. Although present in later spermatids, this region is lost in spermatozoa. Interspecific variations in chromatin condensation patterns and the number of microtubule layers encircling the spermatid nucleus during spermiogenesis were noted.
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Date Issued: 2007

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