Syllidae Grube, 1850 (Annelida) from Southern Africa. A taxonomic update, with a focus on Syllis Lamarck, 1818

[摘要] ENGLISH ABSTRACT: Syllidae is a common polychaete family in South African coastal environments but have not been the focus of research since the publication of a comprehensive polychaete identification guide by Day (1967). Further, they are not listed in any local alien species inventories despite several geographically widespread species (with type localities elsewhere) occurring here. Thus, my aim was to update the list of syllids in Day (1967), allocating each species with a general status: alien, indigenous, cryptogenic or with questionable identifications (i.e., species reported without sufficient information, making their taxonomic status uncertain), using recent publications and databases to update species records. This resulted in 29 taxonomic changes and decreased the total number of valid species from 67 to 59. Additionally, >50% have a questionable taxonomic status; ~ 40% were indigenous, 8% casual and 2% potentially alien. Advancements in technology have led to the dissolution of many questionable species into complexes comprising morphologically similar species, often revealing new indigenous species. Thus, the high prevalence of questionable species among records in Day (1967) suggests an underestimation of native and alien syllid diversity. To test this underestimation, three rocky shore sites were sampled along the south coast of South Africa, a reportedly species rich region for polychaetes overall. Collected individuals were identified to species level and assigned a general taxonomic status as before. More than 600 individuals were collected, representing 13 species with 11 more being unidentifiable. Almost 80% of the species identified had a questionable taxonomy, while the remaining was indigenous. Further, the three most abundant unidentifiable species were described, increasing the total number to 62. Species with questionable taxonomy remain dominant and, along with the many unidentifiable species, makes the underestimation of syllid diversity more apparent. The notion that apparently cosmopolitan species actually represent indigenous species was tested by considering three morphologically similar species; the indigenous Syllis amicarmillaris and the apparently cosmopolitan Syllis armillaris and Syllis amica. The aim was to determine whether S. armillaris, previously considered common in the region but not collected during my study, and the rare S. amica had been identified correctly and are considered as belonging to S. amicarmillaris. Fifty individuals from South Africa and Europe were compared morphometrically, based on 46 characters and using Principal Component and Discriminant Function Analyses and pairwise comparisons. These showed that 1) S. amica from South Africa is morphologically distinct from S. amicarmillaris but similar to specimens from Europe; 2) S. armillaris from South Africa is distinct from European conspecifics but morphologically very similar to S. amicarmillaris, with only four characters weakly significantly different between them. I therefore recommend that S. armillaris from South Africa be referred to as S. cf. amicarmillaris and S. amica from South Africa as S. cf. amica. This shows that two apparently cosmopolitan species have been mis-identified, supporting the the notion that apparently cosmopolitan species actually represent indigenous species. This is especially true for S. cf. amicarmillaris. This study adds two more species to the growing list of questionable species in Day (1967).

[发布机构] Stellenbosch University