Syllis bunaa Sedick & Simon 2019, sp. nov.

Syllis bunaa sp. nov.

(Figures 3B and 5)

urn:lsid:zoobank.org:act: B7110550-8319-47CC-A78D-742C828958C0

Material examined. 20 specimens. Mossel Bay (34°11’6.396”S; 22°9’34.649”E), South Africa, algal turf, lower intertidal, rocky shore, S. Sedick coll., October 2015. Holotype (SAMC-A089057) and four Paratypes, plus one slide of anterior, mid-body and posterior parapodia (SAMC-A089058). Additional material examined. 15 specimens, same data as for Holotype and Paratypes.

Description. Holotype complete specimen, robust, 6 mm long, 0.4 mm wide for 61 chaetigers (additional material 2–9 mm for 49–61 chaetigers). Body cylindrical, dorsally swollen, appearing rounder in cross section anteriorly than posteriorly, becoming less swollen toward posterior body (Fig. 3B). Dark brown pigmentation, almost completely opaque on prostomium and anterior segments, fading toward posterior end, both in vivo and preserved specimens. Dark chocolate to light brown pigmentation that may extend to inner dorsal margins of palps. Intersegmental brown bars, starting just after proventricle, fading toward posterior. Prostomium oval; two pairs of similarly-sized red rounded eyes, in trapezoidal arrangement (Figs 3B, 5A). Median and lateral antennae, dorsal and tentacular cirri distinctly articulated (Figs 3B, 5A). Median antenna longer than palps and prostomium together, originating from middle of prostomium, with 17–23 articles (Fig. 5A). Lateral antennae longer than palps, arising from anterior margin of prostomium, with 13–17 articles (Fig. 5A). Palps basally fused, ovate, similar in length to prostomium. Peristomium shorter than subsequent segments; two pairs of tentacular cirri, dorsal pair with 14–24 articles, ventral pair with 13–18. Dorsal cirri shorter than or subequal to body width, long dorsal cirri with 13–20 articles anteriorly, up to 27 articles in larger specimens, 12–19 articles on midbody parapodia, up to 34 in largest specimens. In holotype dorsal cirri with 27 & 25, 11 & 18, and 21 & 19 articles on left and right parapodia of chaetigers 1 to 3, respectively, up to 22 articles in midbody. Ventral cirri short, not extending beyond parapodial lobes. Parapodia conical, slender. Anterior parapodia each with 6–13 compound chaetae, 6–10 in mid-body, 5–8 in posterior parapodia. Compound chaetae heterogomph bidentate falcigers, with moderately long, thin spines on blades, fine spines on basal margin in some chaetae (Fig. 5 B–D). Proximal tooth always shorter than distal tooth, becoming progressively smaller in mid- to posterior body (Figs 5 B-D). Dorso-ventral gradation in length of blades; 26 µm to 24 µm in anterior; 30 µm to 23 µm in midbody; 24 µm to 22 µm in posterior. On anterior body, length of teeth on falciger blades appear uniform in length but top-most teeth shorter, especially on longer falciger blades. On mid- and posterior body, a clear gradation in length of teeth exists, bottom-most teeth longest. Chaetae with shorter falciger blades may have shorter teeth. Pseudo-simple chaetae by loss of blades and enlargement of shafts differ from shafts of compound falcigers in having broad, narrow shaft, rounded tip or narrow shaft with wide pointed tip (Fig. 5E). Up to three pseudo-simple chaetae may be present in anterior and mid-body only, or along the whole body. Solitary dorsal capillary simple chaetae on posterior parapodia, straight, thick with rounded tip (Fig. 5F 1). Solitary ventral capillary chaetae thin and pointed (Fig. 5F 2) or thick with serrations along inner edge of chaetal shaft (Fig. 5F). Up to three aciculae in each anterior body parapodium of four types: narrow, acuminate, rounded point (Fig. 5G, 1, 2, 3) or distally bent (Fig. 5G 4). Two aciculae in each mid-body parapodium; broad, acuminate, rounded point (Fig. 5H 1) or bent, rounded tip (Fig. 5H 2). One or two aciculae in each posterior body parapodium: broad, acuminate, with rounded tips (Fig. 5I 1) or narrow, pointed tip (Fig. 5I 2). Pharynx extends through 5–8 chaetigers; mid-dorsal pharyngeal tooth small, teardrop shaped, located on anterior margin of pharynx. Proventricle extends through 5–8 chaetigers, with about 26 muscle cell rows (Fig. 5A). Two anal cirri, with 9–16 articles. Pygidium rounded, no median stylus.

Habitat. Algal turf, lower intertidal, rocky shore.

Distribution. Mossel Bay, South Africa.

Etymology. From the Arabic word meaning “brown”, referring to the distinctive brown colour of the worm.