Syllis zahri, Sedick & Simon, 2019

Sedick, Safiyya & Simon, Carol, 2019, Three new species of Syllis Savigny in Lamarck, 1818 (Annelida: Syllidae) from the south coast of South Africa, Zootaxa 4688 (4), pp. 585-598 : 586-588

Syllis zahri sp. nov.

( Figures 1 and 2)

urn:lsid:zoobank.org:act:0CE0E191-5FC5-428C-B884-0A127E09BAB1 Material examined. 15 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-A089053) and two Paratypes: (SAMC- A089054). One specimen and permanent slides of anterior, midbody and posterior parapodia, Additional material examined. 12 complete specimens ( SAMC-A089054 ), data as for Holotype and Paratypes .

Description. Holotype complete specimen 3 mm long, 0.3 mm wide for 44 chaetigers (additional material 2.3

- 5.2 mm for 34 - 53 chaetigers). Body cylindrical, short and broad, tapering posteriorly. In live and preserved specimens, anterior segments light pink to light brown, with two thin dark brown bars running across dorsum at anterior and posterior margins of each of anterior chaetigers ( Fig. 1A); median transverse bands in some ( Figs 1A, 2A). Prostomium oval, with two pairs of red eyes; anterior pair larger than posterior pair, in wide trapezoidal arrangement ( Fig. 1A). Palps basally fused, broadly triangular. Antennae, tentacular and dorsal cirri distinctly articulated ( Fig. 2A). Median antenna inserted between posterior eyes, longer than combined length of prostomium and palps ( Fig. 2A), 16–21 articles long. Lateral antennae longer than palps, arising from anterior margin of prostomium, in front of anterior pair of eyes, with about 14–20 articles ( Fig. 2A). Peristomium shorter than subsequent chaetigers; two pairs of tentacular cirri, dorsal pair with 17–30 articles, ventral pair with 13–20 ( Fig. 2A). Dorsal cirri slender, subequal to or longer than body width; alternate in length; long dorsal cirri with 19–27 articles on anterior parapodia, up to 33 in larger specimens; in holotype dorsal cirri with 25 & 21; 14 & 15 and 17 & 17 articles on left and right parapodia of chaetigers 1 to 3, respectively; up to 21 articles in midbody. Ventral cirri short, not extending beyond parapodial lobe, digitiform. Parapodia conical usually raised or distally rounded on one side, with up to nine, seven, and six compound heterogomph falcigers in anterior, mid- and posterior body, respectively. Anterior parapodia with 7–10 chaetae each, 7–9 in midbody, 6–8 in posterior. Blades of falcigers minutely to strongly bidentate along length of body, proximal tooth about half the length of distal tooth in anterior chaetigers, becoming subequal in mid- and posterior body ( Figs 2 B-D); dorso-ventral gradation in blade length, in anterior parapodia 34 µm to 25 µm ( Fig. 2B), in midbody 36 µm to 27 µm ( Fig. 2C) and in posterior 30 µm to 22 µm ( Figs 2D). Fine teeth on falciger blades throughout body, gradation in length, top-most teeth shortest, bottom-most longest. Pseudo-simple chaetae formed by loss of blade and enlargement of shaft may be present only in anterior or only in midbody or throughout length of body. Solitary pseudo-simple chaetae on each parapodium, of two sizes ( Fig. 2E), rounded tips, with short spines on one margin, often broader than compound chaetae. Solitary dorsal capillary simple chaetae straight, with rounded tip, smooth on margin ( Fig. 2F); solitary ventral capillary simple chaetae slightly curved ( Fig. 2G), unidentate, smooth on margin, only present on most posterior chaetigers. Up to three aciculae per parapodium anteriorly, two in midbody, one or two in posterior parapodia. Anterior aciculae straight, narrow and club-shaped ( Fig. 2H 1), or broad and distally rounded ( Fig. 2H 2, 3); in midbody distally rounded but narrow or broad ( Fig. 2I 1, 2, respectively), posteriorly straight and hollow ( Fig. 2J 1), knobbed ( Fig. 2J 2) or broad and distally rounded ( Fig. 2J 3). Pharynx usually 5–8 chaetigers long (up to 11 chaetigers long in larger individuals); mid-dorsal tooth triangular, located on anterior margin. Proventricle 5–8 chaetigers long, with about 23 muscle rows. Two anal cirri, with14–22 articles. Pygidium with small median stylus.

Numerous protozoans present on dorsum and grooves between dorsal cirri ( Fig. 1B, indicated by arrow), present along body, but more concentrated anteriorly.

Habitat. Algal turf, lower intertidal, rocky shore.

Distribution. Mossel Bay, South Africa.

Etymology. From the Arabic word meaning “pink”, referring to the general colour of the worm.