Peresiella ellae sp. nov.

Figures 2G–I, 3F–H & 4D, E.

Material examined. Holotype: MNHN-IA-2000-2088, incomplete, Northern Atlantic, Bay of Biscay, West Gironde Mud Patch M 2-2C, 45.725°N, 1.629°E, depth 48 m.

Description. Holotype lacking posterior segments, about 12 mm long, 0.2 mm wide for about 39 chaetigers. Body elongate, thread-like, first four thoracic segments short then becoming as long as wide and abdominal segments longer, 4–5x longer than wider; lateral groove present on anterior thoracic region, ventral groove present throughout, deeper on thoracic segments. Colour in alcohol pale yellow.

Prostomium short with conical palpode (Fig. 2G); eyespots absent, nuchal organs not observed but may be present on retracted region of prostomium. Peristomium clearly distinct from prostomium with two annuli each as long as chaetiger 1 (Fig. 2G). Proboscis not observed.

Thorax with eleven segments (Figs 2G; 4E); thoracic segment weakly biannulate. Chaetiger 1 uniramous with two bilimbate notopodial capillaries (Figs 2G; 3F). Chaetigers 2–3 with 4–5 bilimbate notopodial and 4–5 bilimbate neuropodial capillaries. Capillaries short with wide wings (Fig. 3F). Thoracic chaetigers 4–11 with 4–5 spatulate chaetae on both notopodial and neuropodial rami. Notopodial and neuropodial spatulate chaetae similar in shape and length; long and without arista (Figs 2H; 3G).

Transition between thorax and abdomen marked by change in shape of segments and chaetation (Figs 2G; 4D, E); holotype with about 28 abdominal segments, several times longer than wide, multi-annulated (Fig. 4D), with short-hooded hooks throughout. Noto- and neuropodia with well separated glandular tori throughout; notopodial tori dorso-lateral and neuropodial tori lateral.Anterior abdominal segments with 6–7 short hooded hooks, increasing to about 14 short hooded hooks on last segments of fragments. Hooks with short shaft, hoods not extending beyond main fang, lacking distinct node on shaft (Fig. 3H) and 6–7 rows of 8–10 teeth above main fang (Fig. 2I). Branchiae (as notopodial extensions) not observed on fragmented abdomen.

Pygidium not observed.

Methyl Green Staining Pattern. Distinct staining pattern on thoracic region (Fig. 4D, E). Prostomial palpode not stained. Dorsal region of prostomium and peristomium stained with a light green. Thoracic region stained with solid green bands from chaetiger 3 backwards; darker rings present irregularly on a few thoracic segments beginning from chaetiger 5 (Fig. 4D, E).

Remarks. Peresiella species have been distinguished based on the presence of eyespots (present only in Peresiella clymenoides Harmelin, 1968 and P. platyalia Green, 2002), segmental origin and number of segments with modified spatulate chaetae (chaetigers 4–11 in P. clymenoides, P. spathulata Ewing, 1984, and P. megapapilata Silva & Amaral 2022; 4–5 in P. acuminatobranchiata Thomassin, 1970 and 7–10 in P. platyalia), presence of branchiae (as notopodial expansions) and dentition of abdominal hooded hooks (see Table 2 updated after Silva & Amaral 2022). The new species Peresiella ellae sp. nov. is most similar to the type species P. spathulata by the absence of eyespots and presence of modified spatulate chaetae on chaetigers 4–11. It differs on the presence of two peristomial annuli in the new species (Fig. 2G) and peristomium presumably forming a single achaetous region in P. spatulata (Ewing, 1984), shape of thoracic and abdominal segments being multi-annulated and several times longer than wider from the beginning of abdomen in Peresiella ellae sp. nov. number of spatulate chaetae per tori (4–5 in Peresiella ellae sp. nov. and 6–8 in P. spathulata), and dentition of hooded hooks (6–7 rows of 8–10 teeth in Peresiella ellae sp. nov. and 3–4 rows of 10–13 teeth in P. spatulata). Spatulate chaetae in Peresiella ellae sp. nov. lacks arista that was observed in P. spatulata but Ewing (1984) commented that arista were sometimes broken off in some chaetae.

Etymology. This species is dedicated to jazz singer Ella Fitzgerald, as much for her major contribution to music as for her involvement in civil rights.

Type locality. Bay of Biscay, West Gironde Mud Patch .

Habitat. Muddy bottoms, 48 m depth.

Distribution. Only known from the type locality.