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 genus (Porifera, Poecilosclerida) from the Madagascar Ridge.

Family Latrunculiidae Topsent, 1922 comprises seven genera: Latrunculia Barboza du Bocage, 1869; Sceptrella Schmidt, 1870; Strongylodesma Lvi, 1969; Tsitsikamma Samaai Kelly, 2002; Cyclacanthia Samaai Kelly in Samaai et al. (2004); Bomba and Latrunclava Kelly, Reiswig Samaai in Kelly et al. (2016) (Samaai Kelly 2002; Kelly et al. 2016; Samaai et al. 2020), with 83 valid species predominantly in the Southern Hemisphere (de Voogd et al. 2021). Latrunculiidae are differentiated primarily on the form and ornamentation of the diagnostic discorhabd microscleres (see Fig. 1) which may be anisodiscorhabds (Latrunculia, Bomba), isospinodiscorhabds (Cyclacanthia), and isochiadiscorhabds (Tsitsikamma). These may be accompanied by an additional longer microsclere, the amphiclad sceptre and anisoconicorhabd, in Sceptrella and Latrunclava, respectively. Here we describe a new latrunculid genus and species, Biverticillus tenuissimus gen. et sp. nov., from Walters Shoal on the Madagascar Ridge south of Madagascar in the Western Indian Ocean (Fig. 1A), the diagnostic microscleres of which are anisospinodiscorhabds, with two centrally located equidiametral whorls, equally spaced between each other and the apical whorl and manubrium. The microscleres are aniso- in their form because the apical and basal substructures differ slightly in the angle of repose of the spines.

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.

The cushion-star Parvulastra exigua in South Africa: one species or more?

The cushion-star Parvulastra exigua (Lamarck, 1816) is a widely distributed member of the temperate intertidal fauna in the southern hemisphere. In South Africa, it occurs in sympatry with the endemic Parvulastra dyscrita (Clark, 1923), the two species being differentiated predominantly by gonopore placement. Several recent studies have suggested that there may be additional cryptic species within the Parvulastra exigua complex in South Africa, based variously on color morphology, genetic evidence and the differential placement of the gonopores. This paper attempts to resolve whether one or more species are represented within Parvulastra exigua. A total of 346 Parvulastra exigua and 8 Parvulastra dyscrita were collected from sites on the west and south-west coasts of South Africa; morphological, anatomical and genetic analyses were performed to determine whether cryptic species and/or Parvulastra exigua specimens with aboral gonopores were present. Results show that neither cryptic species nor Parvulastra exigua specimens with aboral gonopores occur at these sites. This study thus refutes previous claims of the existence of aboral gonopores in South African Parvulastra exigua, and suggests that a single species is represented. The distinction between Parvulastra exigua and Parvulastra dyscrita is also confirmed, and features separating these two species are clarified and documented.