Raphitoma pusaterii Prkić & Giannuzzi-Savelli, 2020

Prkić, Jakov, Giannuzzi-Savelli, Riccardo, Pusateri, Francesco, Russini, Valeria, Fassio, Giulia & Oliverio, Marco, 2020, Three new species of Raphitoma Bellardi, 1847 (Mollusca, Gastropoda, Raphitomidae) from Croatian waters (NE Adriatic Sea), Zoosystema 42 (16), pp. 215-237 : 226

Raphitoma pusaterii Prkić & Giannuzzi-Savelli n. sp.

( Figs 8 A-F; 9 A-E)

urn:lsid:zoobank.org:act:CE75ED2B-10E0-4971-AAB0-7593588A637E

TYPE MATERIAL. — Holotype. Croatia • lv; MNHN-IM-2000-34889 (height 8.9 mm, width 3.58 mm); Mljet Island ; 60-100 m depth. Paratypes. Croatia • 2 sh; coll. PRK; same locality data as holotype • 2 sh; coll. RGS- 120247, coll. RGS- 120248; same locality data as holotype • 4 sh; coll. LET; same locality data as holotype .

TYPE LOCALITY. — Croatia, Mljet Island; 60-100 m depth.

OTHER MATERIAL EXAMINED. — Croatia • 4 sh; coll. PRK; Mljet Island ; same locality data as holotype • 2 sh; coll. RGS; same local- ity data as holotype • 5 sh; coll. LET; same locality data as holotype • 2 sh; coll. PET; same locality data as holotype • 2 sh; coll. STA; same locality data as holotype .

DISTRIBUTION. — Only known from the material examined.

ETYMOLOGY. — After Francesco Pusateri, for his great and wellknown contribution to the study of the Mediterranean raphitomids.

HABITAT. — All available specimens (including the holotype and 2 paratypes that have dried soft parts inside the shell) were sorted out of dried residues obtained from scuba divers fishing red coral manually at 60-100 m depth. This material consisted of small pieces of fragmented rock, small quantity of mud, sponges, bryozoans, molluscs, brachiopods, echinoderms, etc. In Croatia the red coral community is particularly rich in molluscs, with more than 300 species so far inventoried (Prkić, unpublished data) at various depths and localities. Among them several species of Raphitomidae are common: Leufroyia concinna (Scacchi, 1836) , L. erronea Monterosato, 1884 , L. leufroyi (Michaud, 1828) , L. villaria (Pusateri & Giannuzzi-Savelli, 2008) , Cyrillia linearis (Montagu, 1803) and Teretia teres (Reeve, 1844) ; others are uncommon or rare: Clathromangelia granum (Philippi, 1844) , Pleurotomella gibbera Bouchet & Warén, 1980 , Cyrillia aequalis (Jeffreys, 1867) ; Raphitoma cf. atropurpurea (Locard & Caziot, 1900) , R. bicolor (Risso, 1826) , R. echinata AA. - morphotype 1 [see below], R. cf. ephesina Pusateri, Giannuzzi-Savelli & Stahlschmidt, 2017 , R. farolita F. Nordsieck, 1977 , R. cf. laviae (Philippi, 1844) , R. lineolata (Bucquoy, Dautzenberg & Dollfus, 1883) , R. melitis Kontadakis & Mbazios, 2019 , R. pseudohystrix (Sykes, 1906) , R. pusaterii Prkić & Giannuzzi-Savelli n. sp., R. cf. spadiana Pusateri & Giannuzzi-Savelli, 2012 , and other still unidentified species.

DESCRIPTION [in square brackets the data of the holotype] Shell

Solid and fusiform-acute, of small size for the genus. Height: 6.8-9.2 mm [8.75]; width: 3.0- 3.8 mm [3.57]; h/d: 2.27- 2.54 [2.45].

Protoconch

Multispiral of 3.1-3.3 [3.1] convex whorls, occasionally up to 3.6 whorls ( Figs 2 ; 9B ). Protoconch I of 1.1 whorls 190 µm in diameter, covered by dense cancellate sculpture; protoconch II with axial threads below the suture and less dense and diagonally cancellated sculpture on the rest of whorls. A short median strong keel at the end of last whorl, with minute spiral cordlets in between axial threads above keel. Protoconch-teleoconch boundary of strongly flexuose and opisthocline growth lines. Colour brownish with whitish nucleus, occasionally entirely whitish.

Teleoconch

Of 5.2-6.15 [6.05] slightly convex, stepped whorls, mean 5.7, suture incised, sculpture prominent, whole surface covered with dense microgranules. Axial sculpture of 17-21 [21] orthocline or slightly prosocline (occasionally slightly opisthocline), equidistant ribs, more evident than spiral cords, narrower than interspaces. Spiral sculpture of 21-23 [23] spiral cords on the last whorl, of which 7-8 [8] primary cords, occasionally 6, above the aperture and 2 [2] weak secondary cordlets on the subsutural ramp. Siphonal fasciole with 8-10 [10] strong nodulose cords. Cancellation rectangular, with strong and elongate tubercles at intersections; tubercles on first two primary cords and lower secondary cordlet slightly spinulose. Subsutural ramp very narrow, sometimes with short comma-shaped whitish spots. Columella simple, straight and inclined to the right anteriorly, gently angled posteriorly. Siphonal canal short and widely open at the end; posterior channel wide. Outer lip with 11 [11] occasionally 10 strong inner plicate denticles.

Background colour

Light orange-brownish, sometimes with a yellowish hue, lower part of last whorl occasionally slightly darker. Blotches and spots of variable size and number, white or just slightly lighter than the background colour. Interspaces between tubercles on ribs and cords frequently whitish or just lighter than the tubercles. One or two peripheral cords and some of axial ribs partially (or occasionally entirely) lighter or whitish.

Soft parts

Unknown.

REMARKS

The height and maximum diameter of protoconch depend on the number of whorls; in the photographed specimen ( Fig. 9 A-E) with PW = 3.6 these two features are: H = 646 µm and max. D = 440 µm. All the specimens mentioned in the “Other material examined” paragraph consisted of juvenile or subadult shells.

R. pusaterii Prkić & Giannuzzi-Savelli n. sp. may be easily confused with Raphitoma corbis (Potiez & Michaud, 1838) by their similar colour, sculpture and profile of the shell. However, their protoconchs differ in the number of whorls (3.1-3.6 vs 2.4 in R. corbis ), and as a consequence the protoconch of R. corbis also has smaller height and diameter. Teleoconch characters are mostly similar, but R. corbis does not have the microgranules. Also, the size of the shells seems to be different, the maximum registered height for fully adult R. pusaterii Prkić & Giannuzzi-Savelli n. sp. is 9.2 mm (mean 7.88) vs 12.2 mm (mean 9.75) for R. corbis .

R. contigua ( Monterosato, 1884) also shows some similarities with R. pusaterii Prkić & Giannuzzi-Savelli n. sp., but they differ in the number of protoconch whorls (2.7 in R. contigua vs 3.1-3.6 in R. pusaterii Prkić & Giannuzzi- Savelli n. sp.), max. size of the shell (16 mm in R. contigua vs 9.2 mm in R. pusaterii Prkić & Giannuzzi-Savelli n. sp.), absence of microgranules and more glossy surface of the teleoconch in R. contigua , colour of the shell (light to dark tawny with dark interspaces between the cords in R. contigua vs light orange brownish or yellowish in R. pusaterii Prkić & Giannuzzi-Savelli n. sp.).

Figures

FIG. 8. — Raphitoma pusaterii Prkić & Giannuzzi-Savelli n. sp., Mljet Island: A, holotype, MNHN-IM-2000-34889, h = 8.75 mm; B, paratype, coll. RGS 120247, h = 7.35 mm; C, paratype, coll. PRK, h = 9.2 mm; D, paratype, coll. PRK, h = 7.2 mm; E, paratype, coll. RGS 120248, h = 6.8 mm; F, coll. RGS, h = 5.8 mm.

FIG. 9. — Raphitoma pusaterii Prkić & Giannuzzi-Savelli n. sp., Mljet Island (coll. RGS, h = 3.46 mm): frontal view of shell (A); apical (B), frontal (D) and dorsal (E) view of protoconch; detail of microgranules and transition from protoconch to teleoconch (C). Scale bars: A, 1 mm; B-E, 200 µm.

FIG. 2. — Measurements taken on protoconch of Raphitoma pusaterii Prkić & Giannuzzi-Savelli n. sp.Diameter of nucleus (D nuc. = 105 µm), diameter of first half-whorl (D ½ = 159 µm), diameter of first whorl (D 1 = 190 µm), maximum diameter (Max. D = 440 µm), number of whorls (PW = 3.6), number of whorls of protoconch 1 (PW 1 = 1.1). Scale bar: 200 µm.