Raphitoma stanici Prkić, Giannuzzi-Savelli & Pusateri, 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 : 229-235

Raphitoma stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp.

( Figs 10 A-F; 11 A-E; 12 A, B; 16 A)

urn:lsid:zoobank.org:act:1DA03143-93D0-4960-A911-DFCD255CDB71

Raphitoma sp. A – Russini et al. 2020: 301.

TYPE MATERIAL. — Holotype. Croatia • lv; MNHN-IM-2000-34890 (height 14.33 mm, width 6.38 mm); Sukošan ; 44°01’30”N, 15°20’50”E; 2-6 m depth.

Paratypes. Croatia • 1 lv; MNHN-IM-2000-34891; Brač Island • 5 lv; coll. PRK; same locality data as holotype • 1 lv; coll. PUS- 2801; Brač Island • 1 lv; coll. RGS- 120249; same locality data as holotype • 6 lv; coll. STA; Brač Island • 2 lv; BAU-2256.2, BAU- 2256.3; same locality data as holotype .

TYPE LOCALITY. — Croatia, Sukošan; 44°01’30”N, 15°20’50”E; 2-6 m depth.

OTHER MATERIAL EXAMINED. — Croatia • 4 sh; coll. PRK; Rivanj Island ; 20-30 m depth • 4 lv, 2 sh; coll. PRK; Sukošan ; 44°01’30”N, 15°20’50”E; 2-6 m depth • 12 lv; coll. PET; 44°01’30”N, 15°20’50”E; 2-6 m depth • 5 sh; coll. LET; 44°01’30”N, 15°20’50”E; 2-6 m depth • 5 lv; coll. PET; Biograd, Bošana ; 1-2 m depth • 1 lv; coll. PET; Tribunj ; 2 m depth • 1 lv; coll. PET; Stari Trogir ; 2 m depth • 1 sh; coll. PRK; Voluja • 8 lv; coll. STA; Brač Island , Milna; 8-20 m depth. Sicily • 8 sh; MCZR-M-16899; Gulf of Palermo .

DISTRIBUTION. — Only known from the material examined, in Croatia and in Sicily.

ETYMOLOGY. — After Rino Stanić, for his great contribution to the study of the Croatian molluscs and to the present paper.

HABITAT. — This species has been collected on rocky bottoms with plenty of small and medium-sized stones, on the underside of which the specimens are found at daytime. This is a shallow-water species, most of the live specimens were found at 2-8 m depth, only a few of them were found at 15-20 m depth (R. Stanić, personal communication). R. stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp. often lives in sympatry/syntopy with other raphitomids ( Cyrillia linearis , Leufroyia leufroyi , L. concinna , Raphitoma contigua , R. cordieri AA., R. densa , R. echinata AA. - morphotype 2 [see below], C. cf. ephesina , R. laviae , R. cf. locardi , R. petanii Prkić, Giannuzzi-Savelli & Pusateri n. sp., R. cf. smriglioi , etc.), sometimes with specimens of 5-6 different species occurring under the same stone.

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

Robust and broad, of medium size for the genus. Height: 10.56-19.42 mm [14.33]; width: 5.34-9.17 mm [6.38]; h/d: 1.83-2.3 [2.3].

Protoconch

Multispiral with 2.1 to 2.5 [2.3], convex whorls and large nucleus (d: 150 µm). Protoconch I of 1.2 whorls, 230 µm in diameter, covered by dense cancellate sculpture; protoconch II with well-spaced axial threads under the suture extending as low as to mid-height of whorl, and diagonally cancellate sculpture on the rest of whorl. A short and narrow keel at the end of last whorl. Protoconch-teleoconch boundary of flexuose, opisthocline growth lines. Colour usually dark brown or blackish, with or without white nucleus, occasionally entirely very light cream or very light brownish.

Teleoconch

Of 6.05-7.7 [7.1] convex whorls, suture incised, sculpture very prominent, whole surface covered with extremely fine and dense microgranules. Axial sculpture of 13-18 [14] strong, equidistant, orthocline or slightly opisthocline ribs, much broader than spiral cords, slightly narrower than interspaces. Spiral sculpture of 15-19 [17], spiral cords on the last whorl, of which 5-7 [7] primary cords, above the aperture, first adapical always weaker than second one, starting only at third/fourth whorl; one very weak secondary cordlet on subsutural ramp, with small tubercles at intersection with axial ribs, usually connected by very thin threads. Occasionally on last 0.5-1.5 whorls 1-4 secondary cordlets between primary cords, weak to quite evident. Below periphery 2-4 [2] cords, clearly separated from cords on siphonal fasciole by a wide interspace. Siphonal fasciole with 7-9 [8] nodulose cords, often relatively thin and well-spaced. Cancellation varying from rectangular to squared even on same shell, with very elongate and highly elevated tubercles at the intersections; tubercles on first 3-4 adapical primary cords always spinulose. Subsutural ramp wide and inclined, dark brown or black, with broad white comma-shaped lines. Columella simple, straight and slightly inclined to the right anteriorly, strongly angled posteriorly. Siphonal canal short and widely open at the end, posterior channel wide and relatively shallow. Outer lip with 9-10 [9] strong plicate inner denticles.

Colour

Background colour brown, brown-reddish or grey-blackish, usually darker in the interspaces and on the ramp; light areas, cream, yellowish or light brownish sparse on the shell; a darker band below the periphery. Broad, curved, comma-shaped whitish lines in most interspaces.

Soft parts

Foot long and broad, deeply bilobed anteriorly and with recurved anterolateral corners, narrowly tapering posteriorly. Head small with a pair of long cylindrical tentacles, black eyes on bulges about halfway along their length, distal part slightly longer and much narrower than basal. Colour translucent yellow or yellowish-white, with minute white speckles covering the whole body, including proximal part of tentacles. Siphon black, often with white speckles on the tip. Small greyish areas occasionally present on head, just behind or below tentacles, sometimes extending from mouth area toward the edge of anterior part of foot.

Diagnostic nucleotides

91, 331, 448, 592, 625 (COI), and 304, 348, 357, 358 (ITS2). REMARKS

The height and maximum diameter of protoconch depend on the number of whorls: in the photographed specimen ( Fig. 11 A-E) with PW = 2.5 these two features are: H = 507 µm and max. D = 412 µm. The protoconch is often very small, with just a little over two whorls, in such cases its profile is more cylindrical due to a large nucleus.

When the secondary cordlet on the subsutural ramp is very weak there are always nine denticles and the uppermost one is placed under the interspace between first and second primary cords. In the cases when the secondary cordlet is somewhat stronger there is an additional small denticle placed under the interspace between this secondary cordlet and first primary cord; in such cases the number of denticles is always 10.

A B

After a few years from the time of collecting the shells may look significantly different from fresh ones, especially since the dark colours fade out and the whole coloration becomes lighter.

At low magnification the surface looks like sandpaper with ultra-fine microgrits. The extremely fine microgranules on teleoconch surface ( Fig. 11B ) are similar in size and density to those of the recently described Raphitoma zamponorum Horro, Gori & Rolán, 2019 from São Tomé, which differs in the longer protoconch (over 3 whorls vs 2-1-2.5 whorls in R. stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp.), the higher h/d ratio (2.6 vs 1.8-2.3 in R. stanici Prkić , Giannuzzi- Savelli & Pusateri n. sp.), the fewer axials (11 vs 13-18 in R. stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp.).

We have found no clear phylogenetic affinity for R. stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp. among the other assayed species of Raphitoma , with genetic divergence from the other species ranging from 7% to 12%. Morphologically, R. stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp. may resemble the complex of species referable to R. echinata ( Brocchi, 1814) , which were unfortunately not available for DNA analyses.

The types of Murex echinatus Brocchi, 1814 consist of three inventoried specimens (Museo Civico di Storia Naturale, Milano), with numbers i5427, i5428 and i5429, from the Pliocene (Piacentian) of Italy. The first of them was designated by Pinna & Spezia (1978: 148) as the “ holotype ” and the two others as the “ paratypes ”. According to the ICZN (1999: art. 74.6), in this case Pinna & Spezia actually designated a “ lectotype ” leaving the other two as “ paralectotypes ”. However, the three syntypes belong to 3 different entities. The “ lectotype ” i5427 ( Figs 13A ; 15A ) (h: 21.6 mm, d: 8.38 mm, h/d: 2.58) refers to the species that recent authors identify as R. cordieri (Payraudeau, 1826) . Rossi Ronchetti (1955) also identified this specimen as Philbertia cordieri ( Fig. 14F ). Based on its small size, the fine microgranulation covering the entire shell, the very strong sculpture, and the two denticles adjacent to the posterior siphon more robust than the others, the paralectotype i5429 ( Figs 14A ; 15C, E ) (h: 6.67 mm, d: 2.96 mm, h/d: 2.25), refers to a species of the group of Cyrillia linearis (Montagu, 1803) . The “ paralectotype ” i5428 ( Figs 13D ; 15B, D ) (h: 18.61 mm, d: 7.93 mm, h/d: 2.35) is the only one that corresponds quite well to the figure of Brocchi ( Fig. 13C ), his description and the currently accepted concept of R. echinata . Also, its size is close to that reported by Brocchi (1814; 9 lines = 19 mm). There are many interpretations of Brocchi’s taxon in the literature and various morphs or species have been identified as R. echinata . We suspect that under the nominal taxon “ R. echinata ” of authors a complex of distinct species may be concealed. Pending a revision of the complex based on DNA data, and an extensive study of fossil material (where possibly some nomenclatorial ruling will be necessary), we refer here to the known morphotypes, which may correspond or not to biological species but remain as clear reference for subsequent investigations.Two of them occur in Croatia and are worthy of comparison with R. stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp.: R. echinata morphotype 1 ( Fig. 13E ), the most similar to paralectotype i5428, and so far known only from Croatia, and R. echinata morphotype 2 ( Figs 16D ; 17 ).

R. echinata morphotypes 1 and 2 share with R. stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp. some morphological features: medium size for the genus; multispiral protoconch; short siphonal canal; 9-10 denticles on the outer lip; strong teleoconch sculpture with more or less spinulose tubercles and axial ribs broader than the spiral cords; 14-20 axial ribs; 5-6 primary spiral cords above the aperture; 3-4 spiral cords below the periphery of the last whorl, which are always well separated from the cords on the siphonal fasciole; 7-9 cords on the siphonal fasciole; wide subsutural ramps with broad white comma-shaped lines; similar colour pattern with broad and curved white lines in the interspaces; microscopic and extremely dense granules that cover the whole surface of the teleoconch.

Paralectotype i5428 of Murex echinatus also shows most of these features: medium size for the genus; short siphonal canal; 10 denticles on the outer lip; strong teleoconch sculpture with spinulose tubercles and axial ribs much larger than the spiral cords; 20 axial ribs; six primary spiral cords above the aperture; three spiral cords below the periphery of the last whorl which are well spaced from the cords on the siphonal fasciole; nine cords on the siphonal fasciole.The colour pattern is unknown in this fossil shell and the protoconch is missing.

R. stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp. differs from paralectotype i 5428 in the more robust aspect of the shell, stronger and less numerous axial ribs [13-18 (mean 15.19) vs 20], broader shell [h/d: 1.83-2.25 (mean 2.05) vs 2.35], wider aperture, wider subsutural ramps, presence of microscopic granules, which are absent in paralectotype i5428.

R. stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp. differs from R. echinata morphotype 1 in the darker colour pattern of the shell, the more robust aspect, the wider aperture, the smaller number of protoconch whorls [2.1-2.5 (mean 2.32) vs 3.1-3.35 (mean 3.28)].

R. stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp. differs from R. echinata morphotype 2 in the broader shell, the more elevated and more spinulose tubercles, the wider subsutural ramps, the smaller number of protoconch whorls (2.1-2.5 vs 2.7-3.3), the smaller number of teleoconch whorls at the same shell size (e.g. for h = 18.3 mm TW is 7.5 vs 8.5), the absence of pinkish areas on the teleoconch which are always present in fresh shells of the morphotype 2. They differ also in the colour pattern of the animal, the animal in morphotype 2 ( Fig. 17 ) being always completely white except for some scattered grey speckles occasionally present on the siphon.

Figures

FIG. 10. — Raphitoma stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp.: A, holotype, MNHN-IM-2000-34890, 14.3 mm, Sukošan;B, paratype, coll. STA,14.5 mm, Brač Is.; C, paratype, coll. RGS 120249, 16.1 mm, Sukošan; D, paratype, coll. PRK, 16.5 mm, Sukošan; E, paratype, coll. PUS 2801, 14.3 mm, Brač Is.; F, paratype, coll. PRK, 17.1 mm, Sukošan.

FIG. 11. — Raphitoma stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp., Brač Island, paratype 13, MNHN, 12.4 mm: A, dorsal view of protoconch; B, detail of microgranules; C-D, apical and frontal view of protoconch; E, detail of transition from protoconch to teleoconch. Scale bars: A, C-E, 300 µm; B, 20 µm.

FIG. 12. — A, B, live specimens of Raphitoma stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp.: A, Sukošan, depth 3-5 m, 19.4 mm; B, Biograd, depth 2 m, 16.1 mm. Photos courtesy: A. Petani.

FIG. 16. — A, Raphitoma stanici Prkić, Giannuzzi-Savelli & Pusateri n. sp., paratype, coll. STA, 13.22 mm, Brač Is., Croatia; B, R. echinata sensu Auctores - morphotype 3,12.7 mm, Le Grau du Roi,France;C, R. echinata AA.- morphotype 4, 9.2 mm,Saronic Gulf,Greece;D, E, R. echinata AA.- morphotype 2: D, 18.3 mm, Sevid, Croatia; E, 9.55 mm, Saronic Gulf, Greece; F, G, R. echinata AA. - morphotype 5: F, 9.4 mm, Saronic Gulf, Greece; G, 8.0 mm, Alboran Sea, Spain. Scale bars: 3 mm. Photos courtesy: E, F, Kontadakis.

FIG. 13. — A, Murex echinatus Brocchi, 1814, lectotype, MCSNM i5427, 21.6 mm; B, Raphitoma cordieri (Payraudeau,1826), 22.0 mm, Capraia Is., Italy; C, after Brocchi (1814: fig. 3), 19.0 mm; D, Murex echinatus Brocchi, 1814, paralectotype, MCSNM i5428, 18.6 mm; E, Raphitoma echinata sensu Auctores - morphotype 1, 13.0 mm, Mljet Is., Croatia. Scale bars: 5 mm. A, D: photo courtesy by Michele Zilioli (MCSNM).

FIG. 15. — Murex echinatus Brocchi, 1814: A, lectotype, MCSNM i 5427; B, D, paralectotype, MCSNM i5428; C, E, paralectotype, MCSNM i5429. Photos courtesy: Martina Paolini (MCSNM).

FIG. 14. — Murex echinatus Brocchi,1814:A, paralectotype, MCSNM i5429,6.67 mm; B, box of types; C, probable Brocchi’s original label; D, E, museum labels; F, label written by Rossi Ronchetti. Scale bar: 3 mm. Photos courtesy: Michele Zilioli (MCSNM).

FIG. 17. — Live specimen of Raphitoma echinatasensu Auctores - morphotype 2, Sevid, Croatia, depth 5 m, 18.3 mm.