Free-living marine invertebrates occupy one of two environments as adults -the pelagos or the benthos. Many benthic animals nevertheless occupy the pelagos for a short period of time at some stage in their life, be it as gametes or developing larvae. These temporary components of the plankton are referred to as meroplankton, whilst organisms that remain in the plankton for the full duration of their life are known as holoplankton. The length of time that a life cycle stage is resident in the plankton is related to the trophic mode of that stage. Taxa with lecithotrophic larvae or non-feeding life cycle stages tend to be pelagic for relatively short periods of time, and dispersal is comparatively limited (e.g. Scheltema, 1986). Others have planktotrophic larvae that feed whilst in the plankton, and these may be resident for prolonged periods of time during which they undergo extensive and sometimes complex development and can disperse over much greater distances (e.g. Scheltema, 1986;Avise et al., 1987).The evolution of benthic taxa, because of their obvious association with the seabed and their relatively restricted use of the pelagos, is thought to have been strongly influenced by tectonic and climatic events, and vicariance has been suggested to be the major mechanism leading to allopatric speciation (e.g. Springer, 1982;Heads, 2005). The diversity of the marine benthos is comparatively high, and relatively few species are ABSTRACT Aim Using the genus as the unit of analysis, we examine the relationship between richness, distribution and life cycle strategy for all currently recognized marine Hydrozoa.Location The global marine environment.Methods A global dataset detailing the number of species per genus and the mean date of first description (as a proxy for geographic range size) per genus was assembled for all currently recognized marine Hydrozoa. Differences in means per genus were examined by dominant life cycle strategy (holoplanktic, meroplanktic and benthic) using nonparametric ANOVA and resampling methods.Results By comparison with benthic taxa, holopelagic genera are (on average) significantly less species rich and were described at a significantly earlier date. Taxa with meroplanktic life cycles have a richness and a date of first description that is mid-way between the two extremes.Main conclusions Following from previous work showing that there is a negative relationship between the date of first description and geographic range size, our data indicate that holopelagic taxa not only have fewer species per genus but also have a wider distribution than benthic taxa. These quantitative results are in agreement with long-standing intuitions, and should be applicable to other taxa. They run counter to some recent genetic observations that suggest taxa having planktic larvae might nevertheless show restricted distributions; we argue that this inference reflects a lack of sampling of holopelagic taxa, and a call is made to provide empirical evidence from this realm.

33 species of shallow-water Demospongiae (Phylum Porifera) are described from Sodwana Bay, iSimangaliso Wetland Park, on the east coast of South Africa. Of the 33 species collected, 18 are redescribed from fresh material and 15 are new to science. Orders Clionaida, Poecilosclerida, Axinellida, Haplosclerida and Dictyoceratida are well represented in the collection with 4 to 6 species each, with the first three groups appearing to have the greatest diversity on the east coast of South Africa. The east coast of South Africa appears to have a high abundance of poecilosclerid and dictyoceratid sponges. The results of this study underscore the importance of poecilosclerid and dictyoceratid sponge fauna of the east coast of South Africa, in terms of the potential for the continued discovery of new species.

Sixteen species of Latrunculiidae Topsent, 1922, belonging to the genera Latrunculia du Bocage, 1869, Strongylodesma Lévi, 1969, Cyclacanthia Samaai & Kelly, 2004, Samaai & Kelly, 2002, are currently known from the temperate waters of South Africa. Extensive new sponge collections from the Amathole region of South Africa revealed the existence of three new species of Tsitsikamma, T. amatholensis sp. nov., T. madiba sp. nov., and T. beukesi sp. nov., and a new species of the endemic South African genus Cyclacanthia, C. rethahofmeyri sp. nov. With the recent addition of two new species of Tsitsikamma from Algoa Bay and Tsitsikamma National Park (T. michaeli Parker-Nance, 2019; T. nguni Parker-Nance, 2019) the total number of known South African Latrunculiidae is now 20 species in four genera. Here we propose two new subgenera of Tsitsikamma, Tsitsikamma Samaai & Kelly, 2002 and Clavicaulis subgen. nov., based on the morphological groups “favus” and “pedunculata” hypothesized by Parker-Nance et al. (2019). Species in the nominotypical subgenus Tsitsikamma, containing the type species, are thick encrusting to hemispherical with a rigid honeycombed choanosome, while species in the new subgenus Clavicaulis subgen. nov. have a purse or sac-like morphology with little choanosomal structure. Despite the obvious species-level differences in morphology, multivariate analysis based on spicule measurements (anisostyle length, discorhabd length, shaft and whorl length) was not able to distinguish between the proposed Tsitsikamma species, but separated known species T. favus Samaai & Kelly, 2002, T. pedunculata Samaai & Kelly, 2003, and T. scurra Samaai & Kelly, 2003, from each other. Similarly, DNA barcoding of the mitochondrial COI  and the nuclear ITS of Tsitsikamma specimens failed to clearly differentiate between species, but was able to differentiate sister taxon relationships within the Latrunculiidae.

S. dandelenae sp. nov. is described from the west coast of South Africa and occurs at depths of 80-500 m among unconsolidated sediments. Specimens can reach 40 cm in length and in some areas off South Africa, up to 18 tons/km2 can be collected in a single demersal trawl. Morphologically, the sponge is straw yellow, massive with rounded lobes and has a velvety surface: it is characterized by subradiate, irregular reticulation of bundles of tylostyles and tylostrongyles. Specimens of S. dandelenae sp. nov. have three size classes of tylostyles with the largest tylostyle lengths being 516 μm (441-614 μm), medium tylostyle lengths being 352 μm (307-422 μm) and the shortest tylostyle lengths being 215 μm (153-288 μm). Apart from the presence of tylostyles, some specimens of S. dandelenae sp. nov. also possess centrotylostongyles/oxeas, tylostrongyles and microacanthostrongyles spicules. We have used morphological characters to distinguish this species and a molecular marker (cox1) to conform that all specimens are the same species. At the spicular level, S. dandelenae sp. nov. is characterized by a complex of spicule types that vary with specimen size. Following a histological investigation and re-description of the holotypes of S. ficus (Johnston, 1842) and S. tylobtusus Lévi, 1958, and comparisons with S. carnosus (Johnston, 1842), S. stilensis Burton, 1933, and other Suberites species described from the African region, it is clear that the new species is different in spicule morphology, spicule size and external morphology. For example, microacanthostrongyles are not present in S. tylobtusus and S. carnosus, whilst S. ficus possesses a second, non-spinose category of microstrongyles. Suberites tylobtusus has tylostyles that are sometimes polytylote, with heads either well formed, pear shaped or reduced, in only one size catogory. The 'tylobtuse' condition of the tylostyles is also different to the kidney-shaped and centrotylostrongyles found in S. dandelenae sp. nov. Suberites stilensis Burton, 1933 has larger and thicker tylostyles (800 μm length x 10 μm thick) than those of S. dandelenae sp. nov. A comparative analysis of partial cox1 sequences from morphologically diverse specimens of S. dandelenae sp. nov. with published material indicates that all specimens comprise a monophyletic clade. The combined morphological and genetic data support the designation of Suberites dandelenae sp. nov.

Three new species of Latrunculia are described from Algoa Bay, and Alphard and 45-Mile Banks, on the Agulhascontinental shelf off the southern coast of South Africa. Latrunculia gotzi sp. nov., from Alphard Banks, forms a thickraised pad with broad, low, meandering areolate porefields that are characteristically lighter in colour than the surroundingmahogany brown ectosome. Latrunculia kerwathi sp. nov., from 45-Mile Banks, forms a thin, dark greenish brownencrustation, with very small, discrete, crater-shaped porefields. Latrunculia algoaensis sp. nov., from Algoa Bay, is agreen hemisphere with relatively large, thick-lipped, circular areolate porefields. While the megascleres in these newspecies vary specifically in their dimensions, the former two species have small irregular spines on the styles. Theanisodiscorhabds of the new species also vary specifically in dimensions and degree of ornamentation, but have anundifferentiated basal whorl and manubrium, with only median and subsidiary whorls around the shaft. These are identicalin overall form to the anisodiscorhabds in several South African and New Zealand species currently recognised within thesubgenus Latrunculia (Biannulata) Samaai et al., 2006, a group of 13 species for which no type species was ever assigned. A type species is designated herein.

Originating from the Second International Indian Ocean Expedition (IIOE-2), the main goal of the Western Indian Ocean (WIO) Regional Benthic Imagery Workshop, was to provide information and training on the use of various underwater imagery platforms in benthic research. To date, attempts made to explore the bottom of the ocean range from simple diving bells to more advanced camera systems, and the rapidly expanding field of underwater image-based research has supported marine exploration in many forms, from biodiversity surveys, spatial analyses and temporal studies, to monitoring schemes. Alongside the increasing use of underwater camera systems worldwide, there is an evident need to improve training and access to these techniques for students and researchers from institutes within the WIO. The week-long virtual event was conducted between 30 August and 3 September 2021 with 266 participants. Sessions consisted of lessons, practical demonstrations and interactive discussions which covered the steps required to conduct underwater imagery surveys, taking participants through elements of sampling design, data acquisition and processing, considerations for statistical analysis and, effective managment of data. The session recordings from the workshop are available online as a teaching aid which has the potential to reach marine researchers both regionally and globally. It is crucial that we build on this momentum by continuing to develop and strengthen the network established through this initiative for standardised benthic-image-based research within the WIO.

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