Iphitus (Depressiphitus) davidei, Taviani & Bini & Nappo & Pagli, 2025

Iphitus (Depressiphitus) davidei sp. n.

urn:lsid:zoobank.org:act:7ACCAC51-8B28-416D-883B-E8A395AC16DF

( Figs. 2–3 View FIGURE 2 View FIGURE 3 )

Type material. Holotype: Northeastern Atlantic Ocean: Atlantis Seamount; Seamount 2-DW 264 : 34°24’42 N; 30°30’48 W, 795–830 m ( MNHN-IM-2000-39815 ) GoogleMaps . Paratypes: Paratype 1: Northeastern Atlantic Ocean: Coral Patch Seamount ; 34° 57’ N; 11° 53’ W, 936–965 m ( MZUB 60359 View Materials ) GoogleMaps . Paratype 2: Northeastern Atlantic Ocean: Coral Patch Seamount ; 34° 57’ N; 11° 53’ W, 936–965 m ( MZUB 60360 View Materials ) GoogleMaps . Paratype 3: Atlantic Ocean: Coral Patch Seamount ; 34° 57’ N; 11° 53’ W, 936–965 m ( MZUB 60361 View Materials ) GoogleMaps . Paratype 4: Northeastern Atlantic Ocean: Coral Patch Seamount ; 34° 57’ N; 11° 53’ W, 936–965 m ( MMK n. 34222 ) GoogleMaps .

Description (holotype). Shell morphology as for Depressiphitus subgen. nov. Shell small, fragile, globose-depressed, wider than high (diameter 2.93 mm; height 2.16 mm), white with thin, glossy and translucent surface in fresh specimens (opaque-whitish in old shells). Teleoconch of two rounded whorls separated by deeply impressed suture. Sculpture of numerous weak orthocline axial ribs and 3–5 weak spiral cords. Aperture oval, almost circular, inner lip smooth. Umbilicus open, simple and deep, with a weak spiral sculpture formed by few cords. Protoconch brownish, multispiral, conic-subcylindrical of 3.5 whorls, deviated from axis of teleoconch by about 20°; height 320 µm, diameter 280 µm, strongly sculptured with orthocline axial ribs. Embryonic whorl dome-shaped, smooth. Operculum and animal unknown.

Type locality. Atlantis Seamount (34°24’42 N; 30°30’48 W, at 795–830 m).

Age. Quaternary, possibly subrecent.

Etymology. The species honors the marine biologist Davide Tagliapietra (1960–2023) in recognition of his important contributions on the ecology of the north Adriatic and Venice Lagoon, with special focus on shipworm bivalves.

Habitat. I. davidei sp. nov. is a bathyal species, probably an ectoparasite of unknown cnidarians associated with cold-water coral habitats, as also suggested by the richness in dead scleractinians at both collecting stations.

Epitoniids are all parasites on cnidarians ( Robertson 1970; Beu 1978; Bouchet & Warén 1986; Gittenberger et al. 2000; Gofas et al. 2011; Rueda et al. 2019, with references therein) and we assume that the present new species is no exception. However, this remains speculative at this stage, and we assume that I. davidei parasitizes a still unknown deep-water cnidarian(s), by analogy with a few live-collected Iphitus all found associated with colonial scleractinians (e.g., Beu & Climo 1974; Beu 1978; Taviani & Sabelli 1982; Bouchet & Waren 1986; Rubio Salazar 1987). The skeletal assemblage at Coral Patch included also empty shells belonging to other Iphitus , namely I. tenuisculptus and I. tuberatus . Colonial and solitary dead scleractinian corals (e.g., Madrepora oculata , Madracis sp. ) contributed to the taphocoenoses draping the upper part of the Coral Patch Seamount, and scleractinians occur also in the skeletal assemblage on the Atlantis Seamount. The rather fragile globose shell and very small dimensions of I. davidei sp. nov. could indicate that the species could possibly live embedded within a (small-sized?) cnidarian other than a scleractinian. In the lack of any direct evidence, this hypothesis is only conjectural.

Additional remarks. The best-preserved shell from Coral Patch Seamount was originally selected as holotype but got irreparably damaged after its SEM study ( Fig. 3 View FIGURE 3 ). Therefore, we select as holotype the next best-preserved shell, i.e., a specimen from Atlantis Seamount.