Anguillosyllis carolina, Maciolek, 2020

Maciolek, Nancy J., 2020, Anguillosyllis (Annelida: Syllidae) from multiple deep-water locations in the northern and southern hemispheres, Zootaxa 4793 (1), pp. 1-73 : 30-31

Anguillosyllis carolina n. sp.

Figures 9–10A urn:lsid:zoobank.org:act:70825BC8-0893-49EC-8BD2-4A705D2E3D24

Material examined. (4 specimens from 3 stations). off North Carolina, U.S. South ACSAR Program, coll. J.A. Blake (Battelle), Chief Scientist. Sta. 1, Cruise SA 1, R/ V Columbus Iselin, 11 Nov 1983, Rep. 1, 34°16.40′N, 75°45.01′W, 720 m, paratype ( USNM 1480215 ) . Sta. 12, Cruise SA 6, R/ V Cape Hatteras, 21 Nov 1985, Rep. 1, 33°00.55′N, 76°07.45′W, 1992 m, very soft mud, paratype ( USNM 1480216 ) . Sta. 13, Cruise SA 6, R/ V Cape Hatteras, 20 Nov 1985, Rep. 1, 32°55.16′N, 75°50.25′W, 2999 m, holotype ( USNM 1480214 ) .

Description. Body with 10 setigers ( Figs. 9A , 10B ), slender, linear; all specimens 1–1.3 mm long, 0.25 mm wide without parapodia, 0.6 mm wide with parapodia but without setae. Palps slim, bean-shaped ovals, free to base. Prostomium wider than long, appearing to be in two parts with inner part smaller, dome-shaped anteriorly, slightly raised and outer part inflated, surrounding inner part like a collar ( Fig. 9A ); eyes lacking; antennae long, clubshaped, presumed to be three in total but individual specimens with only one or two. Peristomium with two large tentacular cirri. Nuchal cilia in obvious patches between prostomium and peristomium. Proventricle in 3–4 setigers, oval, barrel-shaped, posterior end not tapered ( Figs. 9A , 10A ); muscle rows not clearly defined, at least 8–10; cells of post-ventricle caeca do not retain MB stain (holotype), or stain very faintly (USNM 1480215).

Dorsum of setiger 1 weakly biannulate, others uniannulate, posterior setigers distorted by eggs. Parapodia uniramous, shortest on setiger 1, becoming longer on setigers 2–3, elongated on setigers 4–10. Very small anterior lobe visible on anterior setigers ( Fig. 9 B–C); posterior lobe small on anterior setigers ( Fig. 9B ), more obvious on later setigers ( Fig. 9C ), especially setigers 8–9, absent on setiger 10 ( Fig. 9D ); dorsal lobe small rounded knob on all setigers. Elongate internal parapodial glands present in all setigers; these few, deep within tissue, some entering dorsal lobe; external glands present on dorsum at anterior and posterior bases of parapodia (visible on holotype in anterior setigers) ( Fig. 9A ). Dorsal cirri present on setigers 1 (holotype) and 4–8, others absent or lost; ventral cirri short, wider at base then tapered, inserted in middle of parapodium.

All setae compound with heterogomph shafts; most setae emerge from distal tip of parapodium, several others from ventral face of parapodium. Setiger 1–2 with ca. 25–35 setae, setiger 3 with ca. 25 setae; setae becoming less numerous in posterior setigers, ca. 16 in setiger 9. Blades ranging in length; shortest ventral falcigers 25 µm long, with narrow, fine (but blunt, not hooked) tips; longest dorsal spiniger-like setae up to 130 µm long, with long fine tips; all blades with deeply serrated proximal area. Parapodia each with two aciculae, not emerging but forming anterior and posterior bumps at distal end of parapodia ( Fig. 9 B–D); aciculae bluntly pointed.

All anal cirri lost.

Oocytes in coelom of setigers 6–9 of all specimens, measuring 60–85 µm greatest diameter; large oocytes entering parapodia.

Remarks. The palps of Anguillosyllis carolina n. sp. are clearly free on the dorsal surface and, while they also appear free to the base, they possibly are connected by a membrane on the ventral surface close to the base: some of the fine structural details of these small specimens were difficult to confirm with light microscopy and the pharynx was everted on one. The prostomium is unusual in appearing to be a structure with two parts, with the inner area slightly raised and the outer portion bearing the antennae; the prostomia of A. denaria n. sp. and A. taleola n. sp. from Brunei are similar.

Anguillosyllis carolina n. sp. differs from most of the other Anguillosyllis species with free or mostly free palps in having 10 rather than 11 setigers. Only A. denaria n. sp. and A. taleola n. sp., both from the South China Sea, also have 10 setigers. Anguillosyllis carolina n. sp. and A. taleola n. sp. are similar in having palps that are entirely free (at least on the dorsal side), whereas A. denaria n. sp. has palps that are fused halfway both dorsally and ventrally. Anguillosyllis carolina n. sp. and A. taleola n. sp. are also similar in having large nuchal patches in comparison to the small ones of A. denaria n. sp. Anguillosyllis carolina n. sp. and A. taleola n. sp. differ in that the former species has small posterior lobes on the posterior setigers except setiger 10, and A. taleola n. sp. lacks these posterior lobes; A. carolina n. sp. has more setae in anterior setigers, and finer-tipped falcigers than A. taleola n. sp., and also has shorter setal shafts relative to blade length (see below).

Etymology. The species name carolina refers to the collection of this species at stations off the coast of North Carolina, USA, during the ACSAR program.

Records. Off North Carolina, USA, 720–2999 m .

Figures

FIGURE 9. Anguillosyllis carolina n. sp. Holotype (USNM 1480214): A, entire specimen, dorsal view. B, setiger 2; C, setiger 5; D, setiger 10. Abbreviations: Acb—acicular bump, acic—acicula, aL—anterior lobe, dC—dorsal cirrus, nuc—nuchal cilia, ip—inner prostomium, op—outer prostomium, phar—pharynx, pL—posterior lobe, prst—prostomium, tC—tentacular cirrus, vC—ventral cirrus.

FIGURE 10. Anguillosyllis carolina n. sp. Holotype (USNM 1480214): A, anterior end, dorsal view.—Anguillosyllis denaria n. sp. Holotype (MCZ 151152): B, entire specimen, dorsal view. Paratype (MCZ 151147): C, setigers 1–5, dorsal view, pharynx, proventricle and post-ventricle MG-stained cells. Holotype (MCZ 151152): D, eggs in coelom of setigers 7–9. Paratype (MCZ 151152): E, setigers 9–10 and pygidium.