Morphological and molecular analysis of Propanagrolaimus siweyae sp. n. (Nematoda: Panagrolaimidae) from Molepo dam, Limpopo Province, South Africa, and its relationship with water parameters

Abstract Panagrolaimidae members are bacterivorous with global distribution. There is no information on this species' morphology and molecular characterization in South Africa. During a survey of Molepo dam, Limpopo Province, a population of Propanagrolaimus nematodes belonging to the family Panagrolaimidae was recovered and determined utilizing conventional and molecular characters. Propanagrolaimus siweyae sp. n., was confirmed by morphological and molecular informations. Propanagrolaimus siweyae sp. n. is characterized by a body length 1026–1258 µm (a = 39.4–45.5, b = 5.4–6.5, c = 8.1–10.0, c’ = 6.9–7.8, V = 53–57), post vulval uterine sac 25–53 µm, and tail length 108–158 µm long. The scan electron microscopy (SEM) photographs revealed a tessellated cuticle and six slightly separated lips. The discriminant analysis placed populations of P. siweyae sp. n. close to P. hygrophilus with clear separation from the mentioned species. Partial sequences of the 18S and 28S regions of the ribosomal DNA gene were amplified for P. siweyae sp. n. The phylogenetic analysis grouped P. siweyae sp. n. in a clade with 1.00 and 0.87 posterior probability values together with other Propanagrolaimus and Halicephalobus based on 18S and 28S rDNA, respectively. Principal component analysis revealed no correlation between Propanagrolaimus and water parameters. However, the result showed a high correlation with diatoms ( r = 0.937) in Molepo dam (site MD-6). In contrast, The PCA showed salinity, pH, and temperature with no significant effect on nematodes in Molepo dam, Limpopo Province, South Africa. In conclusion, the usefulness of free-living nematodes as bioindicators is an advantage to studying pollution in aquatic systems. Limpopo Province is facing pollution in the river and dam systems. Therefore, finding a bioindicator is critical to examine the ecological role of free-living nematodes such as Propanagrolaimus .