Syllis amicarmillaris Simon, San Martin & Robinson 2014

Syllis amicarmillaris Simon, San Martín & Robinson, 2014 Figs 9–12 Syllis amicarmillaris Simon, San Martín & Robinson, 2014: 736–738, figs 7–11. Syllis amicarmillaris – Sedick 2018: 137–138. Material examined SOUTH AFRICA • 3 entire specimens, 4 lacking posterior end; Mossel Bay; 34°11ʹ11ʺ S, 22°09ʹ38ʺ E; Apr.–Oct. 2015; Safiyya Sedick leg.; intertidal algal turf; fixed in 4% seawater formalin, preserved in 70% ethanol; CEAB AP 1003A • 2 specimens, prepared for light microscopy; same collection data as for preceding; CEAB AP 1003B • 2 specimens, prepared for SEM; same collection data as for preceding; CEAB AP 1003C. Other material examined SOUTH AFRICA • 17 complete specimens; Saldanha Bay, Lynch Point, UCT Ecological Survey, station SB155 X; 33°2ʹ52.774ʺ S, 18°0ʹ45.186ʺ E; 22 Sep. 1957; fixed in 4% seawater formalin, preserved in 70% ethanol; SAM-MB-A060395. Description Body long, thick, 8–9.5 mm long 0.6–0.7 mm wide, with 74–90 chaetigers (Figs 9A–B, 11A–B). Prostomium small, with four eyes, with two eyespots in anterior position (Figs 9A–D, 11A, C). Palps triangular (Fig. 9A–D). Median antenna with 15 articles, lateral ones with 11 articles (Figs 9C–D, 11C). Tentacular segment with dorsal (13 articles) and ventral (11 articles) tentacular cirri (Fig. 9C–D, 11C). Dorsal cirri of chaetiger 1 with 15–16 articles, 13–16 in chaetiger 2, 16 in chaetiger 3, and 6–7 (short) and 10–11 (long) in midbody and posterior chaetigers (Figs 9A–F, 11C–E). Parapodial lobes short, with rounded ends (Figs 9G–I, 11C–F). Ventral cirri short, lanceolate with round tips, slightly distally bilobed (Figs 9G–I, 11D, F–H). Compound chaetae heterogomph, bidentate, with very small proximal tooth, and moderately long spines on margin, all similar throughout, with some dorso-ventral and antero-posterior gradation in length (Figs 10A–D, 12A–D, G). Anterior parapodia with 6–9 compound chaetae, blades 36 µm (long), progressively decreasing dorso-ventrally to 17 µm (short) (Figs 10A, 12A). Midbody parapodia with 5–7 compound chaetae, blades 28 µm (long) progressively decreasing to 17 µm (short), with 5–6 segments showing 2–3 pseudo-simple chaetae by loss of blade and with shafts slightly thicker than compound chaetae, not present in all parapodia (Figs 10B–E, 12B–E). Posterior parapodia with 6–10 compound chaetae, blades 28 µm (long), 19 µm (short) (Figs 10F–G, 12F–G). Dorsal simple chaetae straight (Figs 10H, 12H–J), ventral simple chaetae sinuous (Figs 10I, 12K). Three aciculae in anterior parapodia (two with oblique tip, one with acuminate, pointed, straight tip); two in midbody parapodia (one acuminate, one oblique); one in posterior parapodia, with oblique tips, thicker than anterior ones, slightly protruding from parapodial lobes (Figs 10J–L, 12E). Pharynx long, extending over 8–10 segments, with small, conical tooth on anterior margin (Fig. 9A–D). Proventricle similar in length to pharynx, extending through 10–11 segments, with about 41–45 muscle cell rows (Fig. 9A–B). Pygidium with two long anal cirri with 16 articles and a digitiform median appendix (Figs 9A–B, F, J–K, 11B, G–H). Distribution South African coasts. Western Cape Province: west (Saldanha Bay), south-west (west and east Walker Bay – type locality) and south (Mossel Bay). Remarks The specimens collected at Mossel Bay fully agree with the morphology the types of S. amicarmillaris (Simon et al. 2014). Both have similar body shapes and lack pigmentation, have heterogomph, bidentate compound chaetae with small proximal tooth, show midbody pseudo-simple chaetae by loss of blade and enlargement of shaft, have sinuous ventral simple chaetae, long pharynx extending over 8–10 segments, and proventricle equal in length with pharynx extending over 10–11 segments with a similar number of muscular rows. The only observed differences are likely caused by the differences in size, as the types of S. amicarmillaris are longer (32 mm vs 8–9.5 mm in our specimens). Therefore, the number of chaetigers is higher (181 vs 74–90) and the midbody dorsal cirri have more articles (12–19 vs 9–10). Also, the number of parapodia bearing pseudo-simple chaetae is smaller in our specimens, with these chaetae being sometimes present in the parapodia of one side of a segment and absent in that of the other side. Moreover, when present, its number may vary in the two parapodia of the same segment. Samples identified as S. variegata collected in 1957 as part of the UCT Ecological Survey in Saldanha Bay, and possibly identified by John Day, were in fact S. amicarmillaris. These specimens could not be linked to any publications, but they are unlikely to have been used to develop the description of S. variegata owing to the presence of the short dorsal cirri and pseudo-simple chaetae that are characteristic for S. amicarmillaris. The original description of S. amicarmillaris includes populations distributed along the South African coast from Walker Bay (the type locality) to Saldanha Bay (Simon et al. 2014), a distance of approximately 350 km. Although Mossel Bay is somewhat closer to Walker Bay (approximately 260 km away), this geographic distance could still act as a barrier to gene flow. Nonetheless, the available morphological evidence does not support a clear distinction between these populations. Further molecular analyses are needed to determine whether the specimens from Walker Bay and Mossel Bay represent geographically separated populations of a single species or whether speciation has already occurred. Additionally, while Day (1960) reported S. variegata from Mossel Bay —three lots of which matching with S. pseudohyalina sp. nov. — Day (1953) also listed Danger Point as a locality for S. variegata. However, this site is in Walker Bay, very close to the type locality of S. amicarmillaris. These partly overlapping and potentially conflicting records by Day add further confusion to the taxonomic and biogeographic picture of polychaetes from South African coasts, highlighting the need for more detailed morphological and genetic studies to resolve these issues.