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

Sedick, Safiyya (2018-03)

Thesis (MSc)--Stellenbosch University, 2018.

Thesis

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).

AFRIKAANSE OPSOMMING: Syllidae is ‘n algemene borselwurm familie wat gevind word in kusomgewings, maar is nie die hoof fokus van navorsing vanaf die volledige borselwurm studie van Day (1967). Verder word hulle nie gelys in enige plaaslike uitheemse inventaris nie, alhoewel daar verskeie geografies wydverspreide spesies voorkom asook dat die soort ligging van die spesies elders is. My doel was om 'n opgedateerde lys van syllids vanaf Day (1967) te genereer, waar elke spesie 'n algemene status toe geken was soos volg: vreemdeling, inheemse of twyfelagtige identifikasies; deur gebruik te maak van onlangse publikasies en databasisse om spesie rekords te kan opdateer. Dit het gelei tot 29 taksonomiese veranderinge waar die totale aantal spesies verminder het vanaf 67 tot 59. Verder het > 50% 'n twyfelagtige taksonomiese status ontvang; ~ 40% was inheems, 8% ongereeld en 2% moontlik uitheemse spesies. Bevorderings in tegnologie het gelei tot die ontbinding van talle twyfelagtige spesies in komplekse wat morfologies soortgelyke spesies insluit, wat dikwels nuwe inheemse spesies openbaar. Dus dui die hoë voorkoms van twyfelagtige spesies onder rekords in Day (1967) 'n onderskatting van inheemse en vreemde syllid diversiteit. Om hierdie onderskatting te toets, is drie rotsagtige kusgebiede langs die Suidkus (‘n spesies-ryk streek vir borselwurms in geheel) van Suid-Afrika monsters geneem. Versamelde individue is geïdentifiseer volgens spesievlak en 'n algemene taksonomiese status was toegeken soos voorheen. Meer as 600 individue was versamel wat 13 spesies verteenwoordig, terwyl nog 11 spesies onbekendbaar is. Bykans 80% van die geïdentifiseerde spesies het 'n twyfelagtige taksonomie status gehad terwyl die oorblywende spesies as inheems geïdentifiseer was. Verder is die drie mees algehele onbekende spesies beskryf wat die totale aantal spesies tot 62 verhoog. Spesies met 'n twyfelagtige status bly oorheersend in spesiesrykheid en oorvloed, saam met die aansienlike aantal onidentifiseerbare spesies, maak die onderskatting van syllid diversiteit meer duidelik. Met hierdie in gedagte, is die idee dat skynbare kosmopolitiese spesies eintlik inheemse spesies verteenwoordig, dit is getoets deur drie morfologies soortgelyke spesies te oorweeg; die inheemse Syllis amicarmillaris en skynbaar kosmopolitiese Syllis armillaris en Syllis amica. Die doel van die studie was om vas te stel of S. armillaris, wat voorheen algemeen in die streek beskou is, maar nie tydens die huidige studie versamel is nie, en die skaarse S. amica korrek geïdentifiseer is en word beskou as S. amicarmillaris. Vyftig individue van Suid-Afrika en Europa (binne die soort streke van laasgenoemde spesies) is vergelyk met die morfometriese karakters van 46 spesies. Analise van hoofkomponent- en diskriminerende funksie analise en pare vergelykings was gebruik. Die analise het getoon dat 1) S. amica van Suid-Afrika morfologies afsondelik is van S. amicarmillaris, maar soortgelyk is aan die monsters van Europa; 2) S. armillaris vanaf Suid-Afrika is onderskei van Europese spesies, maar morfologies baie soortgelyk aan S. amicarmillaris met slegs vier van 16 karakters wat swak betekenisvol verskil tussen hierdie twee groepe. Daarom beveel ek aan dat S. armillaris van Suid-Afrika verwys kan word as S. cf. amicarmillaris en S. amica van Suid-Afrika, verwys as S. cf. amica. Dit bied bewyse vir die begrip wat vroeër uitgedruk is en toon dat twee skynbaar kosmopolitiese spesies misidentifiseer is.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/103860
This item appears in the following collections: