Repository logo

Entomology

Permanent URI for this communityhttps://hdl.handle.net/10413/7530

Browse

Browsing Entomology by Author "Brothers, Denis John."

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Phylogenetic systematics of Scrapter (Hymenoptera: Anthophila: Colletidae).
    (2006) Davies, Gregory Bernard Peter.; Brothers, Denis John.
    Scrapter Lepeletier de Saint-Fargeau & Audinet-Serville, 1828 (Hymenoptera: Aculeatea: Anthophila: Colletidae) is a genus of solitary bees largely endemic to southern Africa. This dissertation investigated the phylogenetic systematics of the genus. Eleven new species of Scrapter are described, principally from the Succulent Karoo biome of South Africa, bringing the total number of species in the genus to 42. An updated dichotomous key to facilitate identification is provided. The previously unknown females of S. albifumus Eardley and S. amplispinatus Eardley are also described. The genus is recorded from outside southern Africa for the first time with the collection of S. nitidus (Friese) in Kenya. This constitutes a significant range extension of the genus. The taxonomic status of five species described by Cockerell in 1944, and subsequently overlooked, is addressed. They are all found to be synonyms of other Scrapter species, except one, which is found to be a Ctenoplectrina species (Apidae: Apinae: Ctenoplectrini). The new synonymies are: S. subincertus Cockerell = S. niger Lepeletier de Saint-Fargeau & Audinet-Serville; S. brunneipennis Cockerell = S. niger Lepeletier de Saint-Fargeau & Audinet-Serville; S. merescens Cockerell = S. leonis Cockerell; S. sinophilus Cockerell = S. algoensis (Friese). Scrapter ugandica Cockerell becomes Ctenoplectrina ugandica (Cockerell) as a new combination. Investigation of selected morphological features (e.g. postmentum, facial fovea, galea) revealed much diversity in Scrapter. The monophyly of Scrapter is not supported by unambiguous apomorphies, but is defensible by the congruence of various qualitative characters (e.g. premental fovea, T2 fovea, hindleg and sternal scopa in [females], two submarginal cells). A cladistic analysis using 25 morphological characters recovered numerous most parsimonious trees under both equal- and successive-weighting. To aid in resolution, several taxa known from only one sex or from very limited material, and with many unknown states, were deleted from the matrix. Analysis using this reduced matrix under equal- and successive-weighting resulted in better resolution, although with low consistency index values. Several subclades were common to both cladograms, and likely represent monophyla. The low consistency indices and general lack of unique synapomorphies upholding these subclades, however, dictated against making any classificatory re-arrangements.
  • Thumbnail Image
    Item
    Systematic revision of Tricholabiodes Radoszkowski (Hymenoptera: Mutillidae)
    (1998) Bayliss, Paul Spencer.; Brothers, Denis John.
    This study comprises an examination of over 4000 male specimens, including nearly all type material, a detailed study of the genitalia, and a key to the majority of the species of Tricholabiodes Radoszkowski. Thirty species and subspecies are redescribed and 22 new species described. The 22 newly described species are: T. acer, T. alveolus, T. brothersi, T. concavus, T. convexus, T. denticidatus, T. disgregus, T. femoralis, T. ferrugineus, T. indistinctus, T. inornatus, T. longicarinatus, T. liiridus, T. parallel™, T. paulocellatiis, T. petiolatus, T. protitberans, T. recurvatus, T. sinuatus, T. thisboides, T. tortilis and T. trochantalis. Tricholabiodes semisthataeformis Bischoff and T. pathzii Invrea are synonyms of T. stigmaticus Bischoff and T. pallidicornis Bischoff, respectively. Phenograms and principal component plots were derived to clarify species status, make decisions on species limits and used to determine the morphological similarity between the species. The phenetic analysis was used only as a tool, and not a final product. For the determination of species limits, which included an analysis of 447 specimens, the continuous quantitative and coded characters were analysed separately. Forty-three continuous quantitative characters were analysed either as standardized measurements (against mesosoma length) or as ratios (32), since it was not possible, even via gap coding, to code these characters. Scatterplots and a phenogram from the principal components and cluster analyses respectively, are presented. Size and shape were not particularly helpful characters in determining species limits. One hundred and twenty five coded characters were analysed in a cluster analysis and part of the final phenogram is presented. For the determination of morphological similarity between the species, a hypothetical specimen, typical of each species, was derived. Again, one hundred and twenty-five coded characters were analysed in a cluster analysis and the final phenogram is presented. Representatives from each of the species and subspecies were examined with respect to 93 coded characters. The character states were polarised using the outgroup Dasylabroides Andre. Where Tricholabiodes had all states occurring in Dasylabroides, and the primitive state could not be identified, these characters, and their states, were considered for the entire tribe, and the sister tribe of Dasylabrini, Sphaeropthalmini, was taken as the outgroup. The cladograms were constructed with the software Hennig86. The most variable characters were eliminated from the analysis. Selection of the cladogram representing the most likely phylogeny of the genus was based on parsimony, resolution of the tree, character placement on the tree, comparison of the tree with weighted/unweighted consensus trees and biogeography. The phylogeny presented, which is to be regarded only as a hypothesis, suggests that Tricholabiodes underwent nine separate radiations. The southern African species are divided into two lineages: the first divergence stems from the base of the tree while the more recent lineage stems from the apex. Evidence suggests that the genus arose in central Africa, spreading south (twice) into southern Africa, north into North Africa, west across central North Africa and east into southeastern Asia. The study has also shown that the majority of the species are restricted in their distribution, with none of Palaearctic species occurring in southern Africa, and vice versa. It is hypothesised that the present distribution of the genus is partially restricted by dispersal ability and climate.