Confirmation of the southern African distribution of the marine sponge Hymeniacidon perlevis (Montagu, 1814) in the context of its global dispersal.

Background: Intertidal rocky shore surveys along the South African coastline (∼3,000 km) have demonstrated the presence and abundance of the encrusting orange sponge Hymeniacidon perlevis (Montagu, 1814), a well-known globally distributed species. After analysing the southern African populations, we gained a better understanding of the genetic structure of this now-accepted global species. Apart from confirming the presence of a single population of H. perlevis, we also determined its distribution in the southern African intertidal rocky shore ecosystem, compared its genetic diversity to congeners, predict its global distribution via environmental niche modelling, and discussed possible underlying mechanisms controlling the species' global distribution. Methods: We surveyed the South African coastline and sampled sponges at 53 rocky shore sites spanning over 3,000 km, from Grosse Bucht south of Lüderitz (Namibia) to Kosi Bay on the east coast of South Africa. DNA sequences of the nuclear rDNA internal transcribed spacer (ITS1) and the COI mitochondrial gene were obtained from 61 samples and compared them to a world-wide sample of other H. perlevis sequences. Using environmental predictor variables from the global dataset BIO-ORACLE, we predicted the probability of global occurrence of the species using an ensemble of eight distribution models. Results: South African specimens were found to be 99-100% identical to other populations of H. perlevis (=H. sinapium) from other world-wide regions. The presence of a single population of H. perlevis in southern Africa is supported by genetic data, extending its distribution to a relatively wide geographical range spanning more than 4,000 km along the temperate southern African coast. The predicted global occurrence by ensemble model matched well with the observed distribution. Surface temperature mean and range were the most important predictor variables. Conclusion: While H. perlevis appears to have been introduced in many parts of the world, its origins in Europe and southern Africa are unclear.

New Latrunculiidae (Demospongiae, Poecilosclerida) from the Agulhas ecoregion of temperate southern Africa.

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.

A new species of habitat-forming Suberites (Porifera, Demospongiae, Suberitida) in the Benguela upwelling region (South Africa).

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.