Anguillosyllis sepula, 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 : 68-69

Anguillosyllis sepula n. sp.

Figures 30B , 34

urn:lsid:zoobank.org:act:295ABD2B-B8DF-444F-982C-3C26DC786D21

Material examined. South China Sea,off Brunei. (7specimens from 6stations) . Coll. J.A.Blake. Sta. 33, 4 Jun2011, 5 o 48′54.28228″N, 114 o 14′02.81573″E, 1370 m, 1 specimen ( MCZ 150581 ) ; Sta. 45, 2 Jun 2011, 5 o 48′57.88185″N, 114 o 17′18.08262″E, 1260 m, holotype ( MCZ 150582 ) ; Sta. 46, 2 Jun 2011, 5 o 48′02.68476″N, 114 o 18′10.00693″E, 1234 m, paratype ( MCZ 150583 ) ; Sta. 61, 31 May 11, 5°40′32.90422″N, 114°13′15.64893″E, 1050 m, 1 specimen (NJM); Sta. WH-Jokit-SW, 5 Jun 2011, 5 o 46′27.76503″N, 114 o 07′33.98027″E, 1487 m, 1 specimen ( MCZ 150584 ) . Coll. P. Neubert. Sta. TU7, 4 Jul 2011, 5 o 19′24.21956″N, 113 o 47′15.61845″E, 1327 m, 1 specimen ( MCZ 150585 ) ; Sta. TU10, 23 Jun 2011, 5 o 24′42.72532″N, 113 o 51′35.81868″E, 1354 m, 1 specimen ( MCZ 150586 ) .

Description. Body with 10 setigers ( Figs. 30B , 34A ), colorless; holotype 1.2 mm long without anal cirri, 0.25 mm wide without parapodia, 0.5 mm wide with parapodia but excluding setae. Palps completely fused, slightly wider at base, narrowing to somewhat pointed anterior margin; prostomium oval, with three long antennae, eyes lacking; peristomium short, with two oval tentacular cirri. Nuchal cilia not noticeable even when specimen stained with Shirlastain A. Proventricle in 3–4, setigers, bluntly barrel-shaped anteriorly, gently tapered posteriorly; rows of muscle cells indistinct anterior and posterior, ca. 10 rows in middle section ( Figs. 30B , 34A ); post-ventricle with dorsal circlet of cells retaining MG stain ( Fig. 30B ).

Parapodia uniramous, shortest on setiger 1, becoming longer, rectangular over next few setigers, then shorter again on setigers 9–10. Anterior and posterior parapodial lobes absent; dorsal lobe round, curled up or back on some setigers, most obvious on setigers 3–6 ( Fig. 34 C–F); pad of cells that retain MG stain on posterior portion of parapodia, surrounding smooth gland that opens at tip of parapodium ( Fig. 34 D–E). Dorsal cirri long, filamentous, observed only on setiger 1, possibly lost on other setigers. Ventral parapodial cirri digitiform, inserted in middle of parapodium.

All setae compound, heterogomph; setiger 1 with ca. 24 setae, setigers 8–10 with 8–10 setae; several setae emerge from ventral face of parapodium between insertion of ventral cirrus and distal tip, remaining setae emerge from distal tip of parapodium. Ventral falcigers with blunt-tipped blades measuring 20–40 µm ( Fig. 34B ), blades of distal setae long, thin, measuring up to ca. 120 µm in middle setigers. All blades with fine proximal serrations, difficult to see even at 1500x. Parapodia each with at least two aciculae, not protruding but forming anterior and posterior bumps at distal end of parapodia; aciculae with straight or angled tips.

Anal cirri fragile, mostly lost, holotype with one long filiform ventromedial cirrus, another specimen with oval lateral cirrus (lost during examination).

Reproductive specimens with oocytes in coelom of setigers 6–10, oocytes crowded against or entering parapodia ( Figs. 30B , 34A ); oocytes appear especially large in relation to body size, measuring 85–120 µm greatest diameter (ave. = 102.9 µm, median = 107.5 µm).

Remarks. Anguillosyllis sepula n. sp. is most similar to A. blakei n. sp. from offshore California, but lacks the biannulation on the dorsum of the first one or two setigers and also lacks the small anterior and posterior parapodial lobes seen in A. blakei n. sp. The large clear golden tubular gland seen in A. blakei n. sp. is not as obvious in A. sepula n. sp., being more-or-less hidden behind the pad of cells on the posterior part of the parapodium. Anguillosyllis sepula n. sp. is more robust than A. blakei n. sp.: the parapodia are slightly wider and longer when two specimens of a similar size are compared side-by-side, and A. sepula n. sp. has more setae in the first few setigers than A. blakei n. sp. The eggs are also fewer and much larger in A. sepula n. sp. than in other Anguillosyllis species examined.

Etymology. From the Malay word sepuluh, meaning ten; referring to the ten setigers of this species.

Records. South China Sea, off Brunei, 1234–1487 m.

Figures

FIGURE 30. Anguillosyllis hessleri n. sp. Holotype (LACM-AHF Poly 110169): A, entire specimen, dorsal view.—Anguillosyllis sepula n. sp. Holotype (MCZ 150582): B, entire specimen, dorsal view.

FIGURE 34. Anguillosyllis sepula n. sp. Holotype (MCZ 150582): A, entire specimen; B, ventral falciger, setiger 1; C, setiger 2; D, setiger 4; E, setiger 5; F, setiger 7. A, C–F: dorsal view. Abbreviations: dL—dorsal lobe, pap—papillae, phar—pharynx, InGl—internal gland.