Gustav M. Kessel’s research while affiliated with Victoria University of Wellington and other places


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Publications (4)


Kingdom Animalia, phylum Cnidaria (corals, medusae, anemones, hydroids, staurozoans, & myxozoans).
  • Chapter

December 2023

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106 Reads

Diana Macpherson

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Di Tracey

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The total number of described, and known but undescribed, extant marine cnidarian species, from the Aotearoa New Zealand region, is 1420 (Table 6.1; Figs 6.1–6.3). In their first major inventory of the cnidarian fauna of New Zealand, Cairns et al. (2009) recorded 1112 marine species, of which 323 were undescribed or unidentified. Over the last decade there has been a considerable increase in our overall knowledge of cnidarian diversity for New Zealand waters. Described cnidarian species have increased to 1020 and undescribed cnidarians to 400 species. The discovery rate and rate of description of new taxa has increased primarily due to significant new taxa de- scriptions for black corals (Antipatharia) and primnoids (Scleralcyonacea; Primnoidae). The inventory of New Zealand Cnidaria has been updated here and a checklist of extant taxa is included. No updates have been made to the checklist of fossil Cnidaria of New Zealand except for the addition of Bensonularia spatulata (Hamilton 1958).


Fig. 1 A selection of Kotatea lobata (a-c) and K. aurantiaca (d-f) colonies (separated by lines), illustrating the typical range of expanded (a, d), partly expanded (e) and contracted (b, c, f) states exhibited by sets of preserved specimens. Note that depending on the state of expansion/contraction, the two species can resemble one another closely in colony growth form (e.g. differences are not as apparent between b and e or between c and f as they are between a and d)
Novel species discrimination method elucidates colony growth form variation between the New Zealand soft corals Kotatea aurantiaca and Kotatea lobata
  • Article
  • Full-text available

June 2023

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137 Reads

Marine Biodiversity

In New Zealand, Kotatea aurantiaca and Kotatea lobata are two common, endemic, co-occurring, and morphologically similar soft coral species that currently cannot be distinguished without microscopic examination of sclerites and of which little is known regarding any aspect of their ecology or biology. The aim of the present study is to ascertain if, and in what ways, their colony growth forms differ, and to test the taxonomic value of macroscopic morphological character measurements using statistical discrimination analyses. A binary logistic regression model is developed whereby macroscopic characters of colony morphology can be used to assign specimens to either species with ~ 90% accuracy. Species assignment accuracy is greatest when ratios formed from morphological measurements are used rather than direct measurements. Here, these ratios are used for the first time to account for the appearance-altering habit among soft corals of hydrostatically expanding and contracting their coelenteron with seawater. Relationships between colony morphology and depth are also examined, and it is suggested that phenotypic plasticity detected in K. lobata , causing it to resemble K. aurantiaca more closely at greater depths, may contribute to their morphological overlap. It is anticipated that this discrimination technique will facilitate future research on the ecology and biology of these species and will be replicated on other sets of morphologically similar soft corals for which species discrimination has been problematic.

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The use of integrative taxonomy in Octocorallia (Cnidaria: Anthozoa): a literature survey

November 2022

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267 Reads

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3 Citations

Zoological Journal of the Linnean Society

Octocorals are problematic in their systematics, and the extent of their biodiversity is poorly understood. Integrative taxonomy (the use of two or more lines of evidence for the delimitation and description of taxa) is seen as a promising way to produce more robust species hypotheses and achieve taxonomic progress in this group. However, many octocoral descriptions continue to rely on morphological evidence alone, and the prevalence of integrative methods is unclear. Here, a literature survey was conducted to gain an overview of historical description rates and to examine trends in the publication of integrative descriptions between the years 2000 and 2020. We find that recent description rates are among the highest in the history of octocoral taxonomy, and although increasing, integrative taxon descriptions remain in the minority overall. We also find that integrative taxonomy has been applied unevenly across octocoral groups and geographical regions. Description rates show no signs of slowing, and no ceiling of total species richness has yet come into view. Coupled with a continued overreliance on morphological variation, particularly at the species level, this suggests that we might be adding to the workload of taxa requiring future revision faster than such instances can be resolved.


Dead man’s fingers point to new taxa: Two new genera of New Zealand soft corals (Anthozoa, Octocorallia) and a revision of Alcyonium aurantiacum Quoy & Gaimard, 1833

September 2022

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218 Reads

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2 Citations

European Journal of Taxonomy

The taxonomic status of Alcyonium aurantiacum Quoy & Gaimard, 1833, an octocoral endemic to New Zealand, was reviewed through morpho-molecular data comparisons in an integrative approach. Molecular phylogenetic analyses (nuclear 28S and mitochondrial mtMutS) resolved New Zealand taxa as more closely related to other genera and nominal Alcyonium Linnaeus, 1758 from South America than to the genus’ North Atlantic type species. Due to low genetic variation, species delimitation relied predominantly on identifying consistent differences in sclerite and colony morphology. The former A. aurantiacum is reassigned to Kotatea gen. nov. as K. aurantiaca gen. et comb. nov. and seven new species are described in this genus (K. amicispongia gen. et sp. nov., K. lobata gen. et sp. nov., K. kapotaiora gen. et sp. nov., K. kurakootingotingo gen. et sp. nov., K. niwa gen. et sp. nov., K. raekura gen. et sp. nov., and K. teorowai gen. et sp. nov.). Three new species in Ushanaia gen. nov. are also described (U. ferruginea gen. et sp. nov., U. fervens gen. et sp. nov. and U. solida gen. et sp. nov. ). These descriptions increase our understanding of New Zealand’s endemic octocoral diversity and contribute to ongoing systematic revisions of Alcyonium.

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Citations (2)


... It allows researchers to harness the combined strength of various data types, including genetics, morphology, biochemical, and ecological information, to more accurately infer species boundaries [3,18]. This approach is particularly relevant when inferences based on morphology fail, especially when dealing with lineages that contain species complexes or cryptic species [19,20]. Thus, the integration of multiple datasets allows a more comprehensive understanding of the complex evolutionary processes that give rise to unrecognized species [21], such as ecological speciation [22] and incomplete lineage sorting [5]. ...

Reference:

Integrative taxonomy of the genus Coridius Illiger, 1807 (Hemiptera: Heteroptera: Dinidoridae) reveals hidden diversity and three new species from North-East India
The use of integrative taxonomy in Octocorallia (Cnidaria: Anthozoa): a literature survey

Zoological Journal of the Linnean Society

... During taxonomic revision of the nominal soft coral species "Alcyonium aurantiacum" and its associated species Communicated by B.W. Hoeksema complex in New Zealand (Kessel et al. 2022), it became apparent that two of the species involved can be extremely difficult to distinguish based on macroscopic morphological characters, despite being separated by consistent sclerite differences (for details on taxonomic characters see Kessel et al. 2022). Specimens of Kotatea aurantiaca Quoy & Gaimard, 1833 and the newly described K. lobata Kessel et al., 2022(Alcyoniidae Lamouroux, 1812 can be similar in colony growth form and dimensions, as well as in the number and shapes of their colonies' lobes. ...

Dead man’s fingers point to new taxa: Two new genera of New Zealand soft corals (Anthozoa, Octocorallia) and a revision of Alcyonium aurantiacum Quoy & Gaimard, 1833

European Journal of Taxonomy