Morphological and molecular characterization of Butlerius butleri Goodey, 1929 (Nematoda: Diplogastridae) from South Africa: First report.

Two populations of a Butlerius species were recovered from compost in two gardens in Potchefstroom, North-West Province, South Africa. Although the genus has previously been reported from South Africa, no species of the genus has ever been identified in the country. Based on morphological, morphometric, and molecular studies, the specimens were identified as Butlerius butleri and are herein reported for the first time from South Africa. The South African specimens are 1,082 to 1,423 µm long, a = 40.8 to 47.6; b = 4.7 to 5.8; c = 4.0 to 6.0; c' = 117 to 16.3; V = 44 to 47%. Cuticle with evenly spaced punctations. Reproductive system didelphic, amphidelphic, both branches equal in length. Four large glands opening into proximal part of uterus. Males with prominent sphincter present in mid-region of vas deferens. Spicules 36 to 43 µm long, gubernaculum 23 to 31 µm long, nine pairs of genital papillae, three pre-cloacal and six post-cloacal, formula: v1, v2, v3d/v4, ad, ph, v5, 6, 7, pd. The v5, 6, 7 clusters greatly separated, left subventral group at level of phasmid, right subventral group at level of posterior dorsal papilla. Although there were some differences, the South African populations of the species compare well to all know descriptions of the species. Phylogenetic analysis based on partial small subunit (SSU) rDNA sequences showed that both South African populations of B. butleri are in a maximally supported sister relation with an Iranian population of this species. Based on large subunit (LSU) rDNA sequences, the two populations of B. butleri clustered together in a well-supported clade.

Nematodes and the effect of seasonality in grassland habitats of South Africa.

Nematodes in South Africa have mainly been studied for their diversity and agricultural importance. However, the ecological status of nematodes and the effect of seasonal variation in local grasslands remain unknown. For this reason, a nematode study was conducted in the Telperion Nature Reserve and represented the first ecological study in a natural grassland area in South Africa. In total, 104 soil samples were collected during four consecutive seasons from 2015 until 2016 in three habitats, viz. (i) open grassland, (ii) shrubland with rocky outcrops, and (iii) riparian zone. From these the nematode community structure and soil ecosystem status were studied. In total, 93 genera from 50 families were recorded with herbivores and bacterivores being the most abundant trophic groups in all three habitats. Linear mixed models revealed that season had an overwhelmingly dominant impact on the condition, food web status, and functioning of the soil ecosystems with pairwise comparisons indicating that significantly higher values were recorded during winter. Interestingly, this seasonal shift can largely be attributed to fluctuations in the populations of only a few nematode groups (namely Aporcelaimellus, Dorylaimidae, Iotonchus, and Mononchus) with high colonizer-persister values. Although the reason for the higher abundance of specific nematode groups recorded during the winter is not explicitly clear, it is possibly linked to reduced competition from other soil fauna. This study clearly shows that further investigations are required to better understand the dynamics of grassland ecosystems.

Cephalenchus driekieae n. sp. (Nematoda: Tylenchidae) from South Africa, a new member of the genus with a long pharyngeal overlap.

Cephalenchus driekieae n. sp. is described and illustrated based on its morphological, morphometric, and molecular characteristics. This new species is mainly characterized by its short stylet 11.5 to 13.0 µm, and 13.5 to 17.5 µm long pharyngeal overlap extending over the intestine. It could further be delimited by 451 to 526 µm long females with a prominently annulated cuticle, dorso-ventral amphidial openings as shown using scanning electron microscopy (SEM), four lines in the lateral field, anchor-shaped stylet knobs, empty spermatheca, elongate conoid tail with finely rounded tip and males absent. The shortest stylet and long pharyngeal overlap, distinguish this new species from previously described members and update the characteristics of the genus. With four lines in the lateral field, this new species was morphologically compared with four previously described species with this feature and another species with a short stylet. Molecular phylogenetic analyses using the partial small and large subunit ribosomal DNA gene (SSU and LSU rDNA D2-D3) sequences showed that it was clustered with other Cephalenchus spp. in both SSU and LSU trees, retaining the monophyly of the genus. This new species from South Africa updates the biogeography of the genus.Cephalenchus driekieae n. sp. is described and illustrated based on its morphological, morphometric, and molecular characteristics. This new species is mainly characterized by its short stylet 11.5 to 13.0 µm, and 13.5 to 17.5 µm long pharyngeal overlap extending over the intestine. It could further be delimited by 451 to 526 µm long females with a prominently annulated cuticle, dorso-ventral amphidial openings as shown using scanning electron microscopy (SEM), four lines in the lateral field, anchor-shaped stylet knobs, empty spermatheca, elongate conoid tail with finely rounded tip and males absent. The shortest stylet and long pharyngeal overlap, distinguish this new species from previously described members and update the characteristics of the genus. With four lines in the lateral field, this new species was morphologically compared with four previously described species with this feature and another species with a short stylet. Molecular phylogenetic analyses using the partial small and large subunit ribosomal DNA gene (SSU and LSU rDNA D2-D3) sequences showed that it was clustered with other Cephalenchus spp. in both SSU and LSU trees, retaining the monophyly of the genus. This new species from South Africa updates the biogeography of the genus.

Influence of Mining Pollution on Metal Bioaccumulation and Biomarker Responses in Cave Dwelling Fish, Clarias gariepinus.

Cave ecosystems remain largely unstudied and risk being severely degraded as a result of anthropogenic activities. The Wonderfontein Cave, situated in the extensive gold mining region of the Witwatersrand Basin, is one such system that hosts a population of Clarias gariepinus, which is exposed to the influx of polluted mine water from the Wonderfontein Spruit River. The aim of this study was to investigate the bioaccumulation of metals, as well as relevant biomarkers, in C. gariepinus specimens sampled from the Wonderfontein Cave during high (April 2013) and low (September 2013) flow surveys. Results were also compared to a surface population associated with the Wonderfontein Spruit River. There were temporal differences in metal bioaccumulation patterns and this was attributed to the lack of dilution during the low flow period. Metals associated with acid mine drainage, i.e. Co, Mn and Zn were significantly higher in the Wonderfontein Cave population and were reflected in an increase in oxidative stress biomarkers (catalase, protein carbonyls and superoxide dismutase) and the induction of metallothionein, a biomarker of metal exposure. The surface population was exposed to metals associated with geological weathering processes, i.e. Fe and Al.

Soil enzyme profile analysis for indicating decomposer micro-food web.

Highly diverse exoenzymes mediate the energy flow from substrates to the multitrophic microbiota within the soil decomposer micro-food web. Here, we used a "soil enzyme profile analysis" approach to establish a series of enzyme profile indices; those indices were hypothesized to reflect micro-food web features. We systematically evaluated the shifts in enzyme profile indices in relation to the micro-food web features in the restoration of an abandoned cropland to a natural area. We found that enzymatic C:N stoichiometry and decomposability index were significantly associated with substrate availability. Furthermore, the higher Shannon diversity index in the exoenzyme profile, especially for the C-degrading hydrolase, corresponded to a greater microbiota community diversity. The increased complexity and stability of the exoenzyme network reflected similar changes with the micro-food web networks. In addition, the gross activity of the enzyme profile as a parameter for soil multifunctionality, effectively predicted the substrate content, microbiota community size, diversity, and network complexity. Ultimately, the proposed enzymic channel index was closely associated with the traditional decomposition channel indices derived from microorganisms and nematodes. Our results showed that soil enzyme profile analysis reflected very well the decomposer food web features. Our study has important implications for projecting future climate change or anthropogenic disturbance impacts on soil decomposer micro-food web features by using soil enzyme profile analysis.