Filogranula stellata ( Southward, 1963 )

Filogranula stellata ( Southward, 1963) View in CoL

Fig. 6A–F View Figure 6

Ompalopoma stellata Southward, 1963: 576–578 , fig. 3 ( Atlantic Ocean , continental slope of the UK, between 46° and 52°N, 320–1775 m).

Filogranula stellata View in CoL – Bianchi, 1981: 99–100, fig. 38a-c (Mediterranean); Ben-Eliahu & Fiege, 1996: 11–12 (Central and Eastern Mediterranean); ten Hove & Kupriyanova, 2009: 45 (name only), 47, fig. 19A–E (SEM micrographs of chaetae); Kupriyanova et al., 2023 (DNA, phylogeny, Lost City Hydrothermal field, Mid-Atlantic Ridge, SAM E3606): Rosso et al., 2021 (Mediterranean, submarine caves).

Filogranula cf. stellata – Kupriyanova et al., 2011: 52, fig. 5J (tube only, RV “ Vityaz ” Stn. 6348-2, Pacific Ocean, 18º35'N, 175º05'W, 1600–1900 m).

Material examined. W.53461, Territory of Christmas Island, Clara Marie Seamount (13°34'35"S, 105°19'39"E), depth 2189–2264 m, 12/07/2021 (1 tube); W.53462 (LK257), same as above (1 spec.) GoogleMaps ; W.53403 (LK261), Christmas Island SE (10°33'22"S, 105°45'51"E), depth 3200–3345 m, 07/07/2021 (1 spec.) GoogleMaps ; W.53407 (LK269), same as above (1 spec.); W.54390 (LK280), Cocos (Keeling) Islands Territory (12°13'32"S, 96°57'36"E), depth 1113–1343 m, 17/10/2022 (1 spec. prepared for SEM) GoogleMaps .

Species diagnosis. Tube white, opaque, with elaborate star-like peristomes; denticulate keel present ( Fig. 6A View Figure 6 ). Operculum with chitinous concave endplate ( Fig. 6A, C View Figure 6 ). Peduncle smooth cylindrical, without wings, gradually continuing into operculum without constriction ( Fig. 6C View Figure 6 ), inserted as 2 nd dorsal radiole on one side. Seven thoracic chaetigerous segments ( Fig. 6C View Figure 6 ). Collar non-lobed with entire edge, continuous with short thoracic membranes, ending at 2 nd thoracic chaetiger ( Fig. 6D View Figure 6 ). Collar chaetae fin-and-blade and limbate ( Fig. 6F View Figure 6 ). Apomatus chaetae present ( Fig. 6E View Figure 6 ). Illustrations of uncini and abdominal chaetae are given by ten Hove and Kupriyanova (2009, fig. 19).

Remarks. This species with very characteristic tubes bearing denticulate collars was originally described from the Northern Atlantic. Kupriyanova et al. (2011) provided the first (tentative as based on an empty tube only) record of the species from the Pacific Ocean. Most recently, the molecular phylogeny of Kupriyanova et al. (2023) included sequences of a specimen from Lost City Hydrothermal field located on Mid-Atlantic Ridge ( Table 1). This study provided the first record of the species from the Indian Ocean. The phylogenetic results of this study support placement of the collected specimens into Filogranula stellata .

Distribution. North Atlantic Ocean, 320–1775 m; Mediterranean, 700–2485 m; Pacific Ocean, 1600–1900 m; Indian Ocean, Territories of Christmas and Cocos (Keeling) Islands, 1113–3345 m.