Anguillosyllis andeepia, 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 : 46-47

Anguillosyllis andeepia n. sp.

Figures 20–21

urn:lsid:zoobank.org:act:BA33786A-A665-40C1-AE6E-1CBA34BEB6FA

Material examined. South Atlantic Ocean, abyssal plain, South of Meteor Rise (1 specimen from 1 station) Coll. S. Doner ANDEEP III, Sta. PS 67/21-3, 29 Jan 2005, 47°40.05′S, 4°14.84′E, large box corer, 4551 m, holotype ( SMF 24863) .

Description. Body with 8 setigers ( Figs. 20A , 21A ), colorless; holotype slightly longer than 1 mm without anal cirri, 0.2 mm wide without parapodia, 0.5 mm wide with parapodia but excluding setae; posterior appearing somewhat wide and flat due to distortion by eggs. Palps elongated, completely fused, narrowing to softly pointed anterior margin, with faint internal indication of median furrow; prostomium dome-shaped, not well demarcated from palps, with three antennae in transverse row; eyes lacking; peristomium 0.6 mm long, 1.5 times longer than prostomium ( Figs. 20A, C ; 21A ), with two short oval tentacular cirri. No nuchal cilia visible even when specimen stained with Shirlastain A. Proventricle in two setigers, bluntly barrel-shaped anteriorly, slightly tapered posteriorly, rows of muscle cells indistinct ( Figs. 20A , 21A ).

Parapodia uniramous, shortest on setiger 1, becoming longer, rectangular over next few setigers; very small anterior lobe present on all setigers; posterior lobe smallest on setiger 1, becoming much larger through setiger 7, then slightly smaller on setiger 8 ( Figs. 20B , 21B ); dorsal lobe rounded; parapodia without internal glands. Dorsal cirri lost, basal cirrophores present on setigers 1, 3–8; ventral cirri short, digitiform, inserted in middle of parapodium.

All setae compound with heterogomph shafts; setiger 1 with 18–20 setae, setiger 2 with 20–22 setae, remaining setigers with similar numbers, fewer setae in setiger 8. Several setae emerging from distal tip of parapodium, others from ventral face of parapodium; ventral-most blades shortest, 25–50 µm, terminating in pointed tips; longer blades 85–110 µm, with long, fine, drawn-out tips; blades possibly with very fine serrations in proximal portion (difficult to see in light microscope even at 1500x). Parapodia each with two thick, bluntly pointed golden aciculae, not protruding but forming anterior and posterior bumps at distal end of parapodia.

Pygidial cirri lost.

Oocytes in coelom of setigers 5/ 6–8 ( Fig. 21A ), measuring 65–80 µm greatest diameter; some oocytes entering or within parapodia.

Remarks. Anguillosyllis andeepia n. sp. is unique in the proportions of the peristomium, which is 1.5 times the length of the prostomium and much longer than typical Anguillosyllis peristomia; it is also one of only two species encountered in this study that are reproductively mature with eight setigers. The completely fused palps align it with the group of species with similar palps. Of those, four species in addition to A. andeepia n. sp. have large posterior lobes on the parapodia: A. denaria n. sp. from the South China Sea, which has 10 setigers and elongated, slightly rounded palps; A. pupa from the North Atlantic, which has nine setigers and low, rounded palps; an unnamed 9-setiger species from the CCFZ, and A. bruneiensis n. sp. from the South China Sea, which also has eight setigers but has anteriorly rounded palps. In addition to differences in palp structure, all four species have a peristomium that is shorter than the prostomium, in contrast to the deep peristomium of A. andeepia n. sp.

Etymology. This species name is based on ANDEEP, the acronym for the expedition to study deep-sea biodiversity in Antarctica.

Records. Antarctica, 4551 m.

Figures

FIGURE 20. Anguillosyllis andeepia n. sp. Holotype (SMF 24863): A, entire specimen, dorsal view; B, setiger 1; C, prostomium and peristomium, dorsal view, segments delineated. Abbreviations: Acb—acicular bump, aL—anterior lobe, dC—dorsal cirrus, dL—dorsal lobe, pa—palp, pan—prostomial antenna, per—peristomium, pL—posterior lobe, pro—prostomium, tC—tentacular cirrus.

FIGURE 21. Anguillosyllis andeepia n. sp. Holotype (SMF 2463): A, entire specimen, dorsal view; B, setigers 1–5, right side, dorsal view.