# The More You Search, the More You Find: A New Mediterranean Endemism of the Genus Ocenebra Gray, 1847 (Mollusca: Gastropoda: Muricidae) from a Submarine Cave of the Messina Strait Area (Italy)

Fabio Crocetta, Roland Houart, Giuseppe Bonomolo

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Fabio Crocetta, Roland Houart, Giuseppe Bonomolo. The More You Search, the More You Find: A New Mediterranean Endemism of the Genus Ocenebra Gray, 1847 (Mollusca: Gastropoda: Muricidae) from a Submarine Cave of the Messina Strait Area (Italy). Journal of Marine Science and Engineering, 2020, Benthic Biodiversity in the Northeastern Atlantic and the Mediterranean Sea, 8 (6), pp.443. 10.3390/jmse8060443. [https://doi.org/10.3390/jmse8060443](https://doi.org/10.3390/jmse8060443)

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Article

# The More You Search, the More You Find: A New Mediterranean Endemism of the Genus *Ocenebra* Gray, 1847 (Mollusca: Gastropoda: Muricidae) from a Submarine Cave of the Messina Strait Area (Italy)

Fabio Crocetta <fnref n="1" />,* , Roland Houart <fnref n="2" />,<fnref n="3" /> and Giuseppe Bonomolo <fnref n="4" />

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Received: 20 May 2020; Accepted: 12 June 2020; Published: 16 June 2020

**Abstract:** Three hundred years of study on the Mediterranean molluscan fauna led the scientific community to consider it as the best ever known. However, the rate at which new taxa are discovered and described every year is still remarkably high, even in key predators such as Muricidae Rafinesque, 1815. Within this family, the genus *Ocenebra* Gray, 1847 comprises species widely distributed in the northeastern Atlantic and the Mediterranean Sea that were already the target of a decadal nomenclatural, morphological, and molecular combined research. Notwithstanding, we hereby describe an additional ocenebrid endemism from the Mediterranean Sea, whose distribution appears to be restricted to a circalittoral submarine cave of the Messina Strait area (Italy). The new species *Ocenebra vazzanai* is compared with the recent Atlanto-Mediterranean congeneric taxa on the basis of the known type materials, and a table summarizing the main diagnostic features of the species is offered to facilitate future identifications. The high biodiversity highlighted in the genus *Ocenebra* reveals a wide adaptive radiation and suggests the necessity of further studies aiming to tackle biodiversity issues even in popular groups, such as molluscs, and in widely studied biogeographic areas, such as Italy, and the Mediterranean basin in general.

**Keywords:** mussel drills; adaptive radiation; biodiversity; alpha taxonomy; *Ocenebra vazzanai* new species

## 1. Introduction

The Mediterranean Sea has a long history of scientific exploration and is commonly considered a biodiversity hotspot, hosting about 17,000 marine species [1,2]. The Mediterranean Mollusca, in particular, have been the subject of a plethora of studies over the last three centuries, with malacologists producing an extensive bibliography aiming to clarify taxonomical and nomenclatural issues and to discover, as much as possible, the real magnitude of the molluscan biodiversity in the Mediterranean Sea [3,4]. In fact, despite the general crisis of taxonomic studies in recent decades and the increasingly reduced recognition of the importance of taxonomy, which in turn resulted in diminished funding, lower interest from journals in publishing taxonomic research, and a reduced number of young scientists entering the field [5,6], Mollusca always remained a popular,

<footnote n="1">¹ Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Villa Comunale, I-80121 Napoli, Italy</footnote>

<footnote n="2">² Research associate, Institut royal des Sciences naturelles de Belgique, rue Vautier, 29, 1000 Bruxelles, Belgium; roland.houart@skynet.be</footnote>

<footnote n="3">³ Research associate, Institute of Systematics, Evolution, Biodiversity (ISYEB), National Museum of Natural History (MNHN), CNRS, SU, EPHE, UA, CP 51, 57 rue Cuvier, 75005 Paris, France</footnote>

<footnote n="4">⁴ Via Giuseppe Mazzini 9, I-61022 Vallefoglia, Italy; gp.bonomolo@libero.it</footnote>

<footnote>* Correspondence: fabio.crocetta@szn.it</footnote>
and thus frequently investigated group by both professional and amateur malacologists, with more
than 2000 recent taxa recorded in or described from the Mediterranean Sea to date [1,4].

Among them, the family Muricidae Rafinesque, 1815 (oyster drills, mussel drills, and rock shells) includes predators of commercial interest because of their potential impact on marine resources. After centuries of taxonomic studies on muricids of the northeastern Atlantic and Mediterranean [7–24], the local species biodiversity was first summarised by Houart [25], who highlighted the need for a careful revision of several groups. Then, the taxonomy and the phylogenetic position of several species was reviewed by additional authors [26–32], who mostly investigated the subfamily Ocenebrinae Cossmann, 1903 and not only clarified the phylogenetic position of the species formerly ascribed to the genera *Ocenebra* Gray, 1847 and *Ocinebrina* Jousseaume, 1880 but also described several species new to science and synonymised other ones.

Notwithstanding twenty years of continuous work, the alpha taxonomy and the general
biodiversity of the local muricids is still unclear and presumably underestimated. Some genera,
including *Murexsul* Iredale, 1915 and *Muricopsis* Bucquoy & Dautzenberg, 1882, have never been
investigated through an integrative approach (authors' data). Other genera or species still require
additional work. As an example, recent molecular studies suggested that specimens previously ascribed
to *Hexaplex trunculus trunculus* (Linnaeus, 1758) may comprise a complex of cryptic species [33,34],
but the validity of its Levantine congeneric species *Hexaplex pecchiolianus* (d'Ancona, 1871) is still
debated, and nobody has investigated the phylogenetic relationships between these two species to date
(authors' data). Some muricid taxa are widespread and highly polymorphic, e.g., *Ocenebra erinaceus*
*erinaceus* (Linnaeus, 1758), whose distributional range spans from the British Isles to Madeira and the
Azores, including the entire Mediterranean Sea [25,35], whereas other taxa have a restricted distribution
connected to peculiar habitats, e.g., *Ocenebra paddeui* (Bonomolo and Buzzurro, 2006), only known from
northern Sardinia (western Mediterranean) and living in association with the red coral *Corallium rubrum*
(Linnaeus, 1758) [26,36]. A review of the taxonomy of the shallow water taxa of the *Ocenebra edwardsii*
(Payraudeau, 1826) complex revealed the possible presence of several cryptic lineages, some of which
may account for undescribed species [30]. *Ocenebra* taxa, and especially deep-water species, seems to
be rare to absent in the easternmost areas of the Mediterranean basin (i.e., the Levant Sea) [37–39],
thus leaving as unknown whether the area is characterised by a paucity of species or this is the result of
taxonomic impediments and a lack of field studies. Yet, even widely studied biogeographic areas may
reveal the presence of possibly undescribed taxa. This is the case of a new *Ocenebra* species, described
here, from the Messina Strait area (Italy) and only known to date from a circalittoral submarine cave.

**2. Material and Methods**

2.1. *Field Work*

The material examined in the present paper was collected by SCUBA diving by Angelo Vazzana (Associazione-Museo di Biologia Marina e Paleontologia di Reggio Calabria, MBMPRC; Italy) in a circalittoral submarine cave located at a depth of 50–52 m between “secondo dente di Scilla” and “terzo dente di Scilla” and known as “Grotta dei Gamberi” (38°15′25.05″ N, 15°42′46.11″ E) [40,41]. The biogenic sediment of the cave (52 m) was collected with a scoop. The internal surfaces of the cave (50–52 m) were scraped with a broom. The material obtained was subsequently placed in different nets (mesh size: ~0.2 mm) and subsequently transferred to the MBMPRC laboratory. The cave is generally characterised by the presence of benthic communities dominated by poriferans and mostly by the unicorn shrimp *Plesionika narval* (Fabricius, 1787) [40,41]. The nearby area is dominated by cnidarian taxa, among which a *Paramuricea clavata* (Risso, 1826) forest was widely investigated [40–43]. Preliminary results on the living molluscan communities and the local thanatocoenoses of the area were published by Vazzana [41].
## 2.2. Laboratory Work

The biogenic sediment was washed with fresh water and air dried for subsequent sorting under a Skymaster stereomicroscope. Fragments (including complete protoconchs) and shells were mounted on SEM stubs and gold-palladium coated in an SC7640 Sputter Coater for SEM examination with a Jeol JSM-6700 F microscope. Live material was sorted out in Petri dishes filled with sea water soon after sampling. Living molluscs were isolated, photographed with a lightstand and 1–5× macro lens mounted on a Canon EOS 5D, and soon fixed in 70% alcohol for radula extraction. The radula was extracted from the buccal mass after tissues had been partly dissolved in a 10% solution of sodium hydroxide (NaOH), then rinsed in distilled water, air dried on a bed of polyvinyl acetate glue, and gold coated. Photos were taken with a Hitachi s-4300 field emission instrument. Samples were measured with Vernier calipers to the nearest 0.1 mm. Sizes are reported in millimetres and given as total height (TH, from the protoconch to the end of the siphonal canal) × total width (TW, perpendicular from the height line). The analysed material is currently preserved either in private or institutional collections (explanation under individual records).

## 2.3. Nomenclature, Abbreviations, and Acronyms

The following abbreviations and acronyms were also used: AN (Andrea Nappo private collection, Pomezia, Italy); AR (Agatino Reitano private collection, Catania, Italy); FC (Fabio Crocetta private collection, Napoli, Italy); GB (Giuseppe Bonomolo private collection, Jesi, Italy); MBMPRC (Associazione-Museo di Biologia Marina e Paleontologia di Reggio Calabria, Italy); MCZR (Museo Civico di Zoologia, Roma, Italy); MMF (Marine Biology Station of Funchal, Portugal); MNHM (Museo Civico di Storia Naturale, Milano, Italy); MNHN (Muséum National d'Histoire Naturelle, Paris, France); NHMUK (The Natural History Museum, London, U.K.); RH (Roland Houart private collection, Landen, Belgium); SMF (Senckenberg Museum Frankfurt, Frankfurt/Main, Germany); SZN (Stazione Zoologica Anton Dohrn, Naples, Italy); sh, shell(s); lv, specimen(s); TH (total height); TW (total width).

Abbreviations used for spiral sculpture and internal denticles in Muricidae follow Merle [44,45]: IP (infrasutural primary cord); abis (abapical infrasutural secondary cord); P1–P6 (primary cords of the convex part of the teleoconch whorl); s1–s5 (secondary cords of the convex part of the teleoconch whorl); t (threads); ADP (adapical siphonal cord); D1–D5 (denticles within the apertural outer lip).

Updated species taxonomy and nomenclature follow MolluscaBase [46], unless differently stated.

# 3. Results

## 3.1. Systematics

- Phylum Mollusca Cuvier, 1797

- Class Gastropoda Cuvier, 1795

- Subclass Caenogastropoda Cox, 1960

- Order Neogastropoda Wenz, 1938

- Superfamily Muricoidea Rafinesque, 1815

- Family Muricidae Rafinesque, 1815

- Subfamily Ocenebrinae Cossmann, 1903

- Genus *Ocenebra* Gray, 1847

*Ocenebra vazzanai* sp. nov. (Figure 1A–G and Figure 4C)

urn:lsid:zoobank.org:pub:83D771F2-E8FA-45F7-9CB4-851912659ADF

## 3.2. Material Examined

Type material. Holotype: one shell (SZN-MOL034—15.5 × 8.5). Paratypes: A-one shell (SZN-MOL035—14.9 × 8); B-one shell (SZN-MOL036—14 × 7); C-one shell (SZN-MOL037—15 × 8); D-one shell (SZN-MOL038—15.5 × 8); E-one shell (SZN-MOL039—16.1 × 8.2); F-one shell (SZN-MOL040—18.4 × 9.6); G-one damaged shell (broken apex) (SZN-MOL041—16.2 × 10); H-one
specimen (shell broken to analyse radular features) (SZN-MOL042—12.9 × 8.1); I-one juvenile specimen (SZN-MOL043—4.5 × 2.3). All specimens/shells listed here come from the type locality.

Additional material. One golden-coated stub, on which (among others) both the specimen used to represent juveniles and the selected protoconchs are mounted (SZN-MOL044); one shell (FC—16 × 7.8); one shell (GB—15 × 7.6); one shell (RH—15.1 × 7.5); four shells (MBMPRC—12.2 × 6.4; 11.3 × 6.1; 16.2 × 9.3; 12.1 × 7); 12 juvenile shells (MBMPRC); 40 fragments (MBMPRC). All shells listed here come from the type locality.

### 3.3. *Type Locality*

Grotta dei gamberi (Scilla, Reggio Calabria, Italy) (38°15′25.05″N, 15°42′46.11″ E), 50–52 m depth.

### 3.4. *Description*

Species with solid and fusiform shell, slightly scalariform appearance. Medium-sized for the genus, TH up to 18.4 mm (paratype F) and TW up to 10 mm (paratype G) (15.5 × 8.5 mm in the holotype—Figure 4C). Paucispiral protoconch of 1.25–1.5 rounded whorls (holotype: 1.5) (Figure 1E), globose, apparently smooth, with micro-sculpture of several irregularly shaped granules, ca. 5 µm in diameter (Figure 1F–G). Teleoconch of 5.5–6 convex whorls at maturity (holotype: 5.5), elongated but rounded, broad in median zone, with last whorl consisting of ca. ⅜ of total height.

Protoconch amber, teleoconch pale brown, reddish, or orangish in colour, sometimes with whitish spiral band in median zone, and occasional second tiny whitish spiral band near siphonal canal (paratype C); dark spots on ribs, in proximity of spiral cords, often more expanded on P1 (Figure 1A and Figure 4C); edge of aperture white, pale brown within. Subsutural ramp slightly angled, fairly broad, with adpressed suture.

Spiral sculpture of convex part of whorl consisting of six nodose, rounded primary cords, higher and more spinose on last whorl, alternated by smaller secondary cords and smaller threads (holotype: present) (Figure 1A,C and Figure 4C). IP, P1, and P2 starting from first teleoconch whorl, soon followed by abis from second whorl, while s1 and s2 can start from second to third whorl (holotype: s1 from second whorl, s2 from third whorl, and abis from second whorl). P3 often visible from third whorl, but sometimes partially covered by subsequent whorl. Axial sculpture consisting of rounded and nodose ribs: 13 or 14 on first teleoconch whorl; 11–13 on second; 10 or 11 on third; nine or 10 on fourth; eight or nine on fifth and on last whorl (holotype: 12 on first whorl; 11 on second; 11 on third; 10 on fourth; nine on the last whorl: Figure 1A,B and Figure 4C). Ribs usually more prominent, high and spinose on last whorl or rarely on penultimate and last whorl, occasionally with one or two erratically placed varices, and one or two strong nodes on last whorl.

Aperture (Figure 1C) slightly narrow, elongate-ovate, outer apertural lip crenulate, erect, with five strong internal denticles: D1–D5 (one rarely split), ID absent. Labral varix slightly high and expanded, from nodose-rounded to spiny aspect. Columellar lip smooth, slightly expanded ventrally, erect abapically and adherent adapically. Labral tooth absent. Siphonal canal moderately long, ventrally sealed and dorsally spirally sculptured (Figure 1C).

Animal translucent with pale brown/whitish spots all over body, yellow spots at base of foot and at end of ocular tentacles, black eyes (Figure 1A). Radula typical of Ocenebrinae, with sickle-shaped lateral teeth with broad base, rachidian bearing short and thick central and lateral cups with short and thick inner lateral denticle on base. Marginal area with short denticles and thick marginal cusp (Figure 1B).
<figure><img src="image_4.png" /><figcaption>**Figure 1.** *Ocenebra vazzanai* sp. nov. (A,B) Paratype H (SZN-MOL042—12.9 × 8.1): details of the animal and its radula. (B) Scale bar: 10 µm. (C) Holotype (SZN-MOL034—15.5 × 8.5): spiral sculpture on the last whorl and internal denticles (for acronyms see "Abbreviations used"). (D) Juvenile specimen (SZN-MOL044): adapertural view and protoconch-teleoconch border. Scale bar: 200 µm. (E) Protoconch (SZN-MOL044): apical view. Scale bar: 100 µm. (F,G) Protoconch (SZN-MOL044): general microsculpture and higher magnification (Figure 2G corresponds to the black square in Figure 2F). (F,G) Scale bars: 10 µm.</figcaption></figure>
### 3.5. Etymology

Named after Angelo Vazzana (male), scientific director of MBMPRC (Italy), who provided the material studied here.

### 3.6. Distribution

A species endemic to the Mediterranean Sea, to date restricted to its type locality.

### 3.7. Taxonomic Remarks

*Ocenebra vazzanai* sp. nov. is easily distinguishable from the other northeastern Atlantic and Mediterranean species of *Ocenebra* and *Ocinebrina* due to its unmistakable shell. In fact, the shell of *O. vazzanai* only partially resembles that of *Ocinebrina reinai* Bonomolo and Crocetta, 2012 due to the colour pattern with presence of dark spots on ribs and the spiral and axial sculpture of the teleoconch. However, *Ocinebrina* taxa are characterised by animals with reddish colour patterns, contrarily to the creamish pattern of the *Ocenebra* taxa. *Ocinebrina reinai* is also smaller than *O. vazzanai*, lacks the general spiny aspect of the last whorl, and has a different aperture, with the presence of ID and sometimes of a labral tooth. With regards the congeneric species, the *Ocenebra* taxa more similar to *O. vazzanai* are *O. helleri* (Brusina, 1865), *O. nicolai* Monterosato, 1884, and *O. paddeui* Bonomolo and Buzzurro, 2006 due to the general teleoconch aspect of their shells and the known depth range. However: i) *Ocenebra helleri* has a more scalariform appearance than *O. vazzanai*, its spiral sculpture is stronger and conspicuous all over the shell (in *O. vazzanai* it is mostly visible on the axial sculpture and varices), P3 is always visible from the third whorl, its general aspect is less spiny and more nodose, and the shell usually lacks dark spots on the ribs. In addition, *Ocenebra helleri* has five strong and conspicuous teeth, but often one, and sometimes two, are split, whilst *O. vazzanai* has always five strong teeth and rarely one is split; ii) *Ocenebra nicolai* is rounder than *O. vazzanai*, has larger whorls, and the general teleoconch aspect is quite different due to a stronger sculpture and the absence of spiny varices. Moreover, the teleoconch colour is usually lighter, with an absence of brown spots; iii) *Ocenebra paddeui* has a smooth protoconch with obvious growth lines, is slenderer than *O. vazzanai*, and lacks both its typical spiny and scalariform aspect. It also mostly differs in the lesser number of axial ribs and, as in *O. nicolai*, it always lacks dark spots on the ribs. No other fossil species of European Muricidae assigned to the genera *Ocenebra* or *Ocinebrina* is close enough to *O. vazzanai* to require further comparisons [47–53]. We here deepen the differences between *O. vazzanai* and the recent northeastern Atlantic and Mediterranean congeneric species in Table 1 and also offer an amended comparative plate of the small species of the genus so as to facilitate future identifications (Figures 2–4).
<table><caption>**Table 1.** Comparative table of the recent northeastern Atlantic and Mediterranean species of the genus *Ocenebra* Gray, 1847. Data amended from [21,25–28,30,35,36,54–57].</caption><thead><tr><th></th><th>O. [erinaceus] erinaceus<br>(Linnaeus, 1758)</th><th>O. [erinaceus] brevirobusta<br>Houart, 2000</th><th>O. chavesi<br>Houart, 1996</th><th>O. edwardsii<br>(Payraveau, 1826) complex</th></tr></thead><tbody><tr><td>Figures</td><td></td><td></td><td></td><td>2A-E</td></tr><tr><td>Shell TH (in mm)</td><td>up to 65</td><td>up to 42</td><td>up to 21.4</td><td>up to 26.82</td></tr><tr><td>Protoconch</td><td></td><td></td><td></td><td></td></tr><tr><td>w: whorls</td><td>w: 1.25-1.5</td><td>w: 1.5</td><td>w: 1.5</td><td>w: 1.25-1.5</td></tr><tr><td>m: microsculpture</td><td>m: smooth</td><td>m: smooth</td><td>m: smooth</td><td>m: smooth or with small granules</td></tr><tr><td>Teleoconch</td><td>ga: fusiform, rounded whorls</td><td>ga: rounded</td><td>ga: rounded, slightly scalariform</td><td>ga: rounded, scalariform</td></tr><tr><td>ga: general aspect</td><td>w: up to 7</td><td>w: up to 6</td><td>w: up to 6</td><td>w: up to 6.5</td></tr><tr><td>w: whorls</td><td>cp: whitish, light tan, pale brown,</td><td>cp: pale or dark brown</td><td>cp: light tan or pale brown</td><td>cp: various (from whitish to dark<br>brown, usually light tan with brown<br>blotches or whitish spiral bands)</td></tr><tr><td>cp: colour pattern</td><td>occasionally with darker spiral bands</td><td></td><td></td><td></td></tr><tr><td>Teleoconch sculpture of the<br>convex part of the last whorl</td><td>a: 3-11 low or high, rounded,<br>occasionally strong varices</td><td>a: 4-6 broad, large, rounded varices,<br>occasionally very low</td><td>a: 6-7 broad, high, squamous ribs</td><td>a: from 7-9 low, rounded, nodose or<br>occasionally spinose ribs, usually<br>with 1-2 erratically placed varices</td></tr><tr><td>a: axial</td><td>s: 6 primary cords alternated by</td><td>s: 6 primary cords (with obsolete P2)</td><td>s: 6 primary cords alternated by</td><td>s: 6 narrow and strong primary<br>chains alternated by smaller<br>secondary cords</td></tr><tr><td>s: spiral</td><td>smaller secondary cords</td><td>alternated by smaller secondary cords</td><td>smaller secondary cords</td><td>chains alternated by smaller<br>secondary cords</td></tr><tr><td>t: threads</td><td>t: often present</td><td>t: occasionally present</td><td>t: often present</td><td>t: present, occasionally absent</td></tr><tr><td>Aperture</td><td>ga: moderately large, elongate-ovate,<br>whitish internal colour</td><td>ga: moderately large, broad, roundy-ovate,<br>whitish internal colour</td><td>ga: moderately large, ovate, whitish<br>internal colour</td><td>ga: large, ovate, white or pale<br>brown internal colour, with<br>occasionally whitish spiral bands</td></tr><tr><td>ga: general aspect</td><td>cl: narrow, smooth, adherent</td><td>cl: narrow, smooth, adherent</td><td>cl: smooth, adherent</td><td>cl: narrow, smooth, adherent</td></tr><tr><td>cl: columellar lip</td><td>adapically</td><td>adapically</td><td>adapically</td><td>adapically</td></tr><tr><td>ol: outer lip</td><td>ol: weakly crenulate</td><td>ol: crenulate</td><td>ol: crenulate</td><td>ol: crenulate, erect.</td></tr><tr><td>d: denticles</td><td>d: from absent to 5 weak or strong,</td><td>d: 5 strong, occasionally some could<br>appear double</td><td>d: 5 weak, sometimes one could<br>appear double</td><td>d: 5 weak, sometimes one could<br>appear double</td></tr><tr><td>ID: infrasutural apertural<br>denticle</td><td>occasionally some could appear<br>double</td><td>ID: occasionally present</td><td>ID: occasionally present</td><td>ID: absent</td></tr><tr><td>lt: labral tooth</td><td>ID: occasionally present<br>lt: absent</td><td>lt: absent</td><td>lt: absent</td><td>lt: absent</td></tr><tr><td>Radula rachidian cusps</td><td></td><td></td><td></td><td></td></tr><tr><td>c: central</td><td>c: elongate but quite thick</td><td>unknown</td><td>c: elongate but quite thick</td><td>c: elongate</td></tr><tr><td>l: lateral</td><td>l: elongate but quite thick</td><td>unknown</td><td>l: elongate but quite thick</td><td>l: elongate</td></tr><tr><td>Animal general colour pattern</td><td>creamish</td><td>unknown</td><td>unknown</td><td>creamish</td></tr><tr><td>Depth range (in m)</td><td>0-130</td><td>littoral</td><td>10-22</td><td>0-70</td></tr><tr><td>Distribution</td><td>Atlantic-Mediterranean</td><td>Atlantic</td><td>Atlantic</td><td>Atlantic-Mediterranean</td></tr><tr><td>Notes</td><td>1</td><td>1</td><td></td><td>2</td></tr></tbody></table>
<table><caption>Table 1. *Cont.*</caption><thead><tr><th></th><th>O. helleri<br>(Brusina, 1865)</th><th>O. hybrida<br>(Aradas and Benoît, 1876)<br>-<br>O. piantonii<br>(Cecalupo, Buzzurro, and Mariani, 2008)</th><th>O. inordinata<br>Houart and Abreu, 1994</th><th>O. miscowichae<br>(Pallary, 1920)</th></tr></thead><tbody><tr><td>Figures</td><td>2F</td><td>3A, possibly 3B, and 3C (see Notes)</td><td>3D</td><td>3E</td></tr><tr><td>Shell TH (in mm)</td><td>up to 23</td><td>up to 18.5</td><td>up to 21</td><td>up to 22</td></tr><tr><td>Protoconch</td><td>w: 1.5</td><td>w: 1.25-1.5</td><td>w: 1.25-1.5</td><td>w: 1.25</td></tr><tr><td>w: whorls</td><td>m: smooth with small and dense granules, often with well visible</td><td>m: uncertain, presumably with small granules</td><td>m: unknown</td><td>m: unknown</td></tr><tr><td>m: microsculpture</td><td>dense growth lines on the last half whorl</td><td></td><td></td><td></td></tr><tr><td>Teleoconch</td><td>ga: slender, scalariform</td><td>ga: rounded, scalariform</td><td>ga: shouldered, strongly nodose</td><td>ga: rounded, scalariform</td></tr><tr><td>ga: general aspect</td><td>w: up to 6.5</td><td>w: up to 5</td><td>w: up to 6</td><td>w: up to 5</td></tr><tr><td>w: whorls</td><td>cp: from pale orange to light tan, often with a whitish spiral band in</td><td>cp: various (uniformly light or dark brown, blackish or whitish, occasionally with one or two spiral bands in median zone)</td><td>cp: light brown</td><td>cp: uniformly light tan or light tan with darker spiral bands</td></tr><tr><td>cp: colour pattern</td><td>median zone (sometimes two)</td><td></td><td></td><td></td></tr><tr><td>Teleoconch sculpture of the convex part of the last whorl</td><td>a: 6-13 broad, rounded, nodose ribs, occasionally with an erratically placed varix</td><td>a: from 3-5 to 6-7 narrow, high, spinose varices, occasionally with weak nodose ribs</td><td>a: 4-5 varices alternated by 1-2 high strong nodes</td><td>a: 7-9 low, weakly nodose ribs</td></tr><tr><td>a: axial</td><td>s: 6 high and rounded primary cords</td><td>s: 6 narrow and strong rounded primary</td><td>s: 6 low shallow primary cords</td><td>s: 6 strong and narrow primary</td></tr><tr><td>s: spiral</td><td>alternated by smaller secondary cords</td><td>cord alternated by smaller secondary cords</td><td>alternated by smaller secondary cords</td><td>secondary cords</td></tr><tr><td>t: threads</td><td>t: absent</td><td>t: present</td><td>t: occasionally present</td><td>t: occasionally present</td></tr><tr><td>Aperture</td><td>ga: moderately large, ovate, brown internal colour</td><td>ga: large, ovate, white or black internal colour</td><td>ga: moderately large, ovate, white internal colour</td><td>ga: moderately large, ovate, white internal colour with brown spiral bands</td></tr><tr><td>ga: general aspect</td><td>cl: narrow, smooth, weakly erect</td><td>cl: smooth, adherent, weakly erect</td><td>cl: smooth, margin partially weakly erect, adherent</td><td>cl: narrow, smooth, adherent</td></tr><tr><td>cl: columellar lip</td><td>abapically, adherent adapically</td><td>abapically</td><td>ol: crenulate, erect</td><td>ol: crenulate, erect</td></tr><tr><td>ol: outer lip</td><td>ol: crenulate, erect</td><td>ol: crenulate</td><td>d: 5 strong, sometimes one could appear double</td><td>d: 5 weak, sometimes one could appear double</td></tr><tr><td>d: denticles</td><td>d: 5 strong and well-marked, often one (or two) appear/s double</td><td>d: 5 strong, sometimes one could appear double</td><td>d: 5 strong, sometimes one could appear double</td><td>d: 5 weak, sometimes one could appear double</td></tr><tr><td>ID: infrasutural apertural denticle</td><td>ID: occasionally present</td><td>ID: absent</td><td>ID: absent</td><td>ID: absent</td></tr><tr><td>lt: labral tooth</td><td>lt: absent</td><td>lt: absent</td><td>lt: absent</td><td>lt: absent</td></tr><tr><td>Radula rachidian cusps</td><td></td><td>c: elongate</td><td>unknown</td><td>unknown</td></tr><tr><td>c: central</td><td>unknown</td><td>l: elongate</td><td>unknown</td><td>unknown</td></tr><tr><td>l: lateral</td><td></td><td></td><td></td><td></td></tr><tr><td>Animal general colour pattern</td><td>creamish</td><td>creamish</td><td>unknown</td><td>unknown</td></tr><tr><td>Depth range (in m)</td><td>20-80</td><td>0-8</td><td>14-86</td><td>infralittoral</td></tr><tr><td>Distribution</td><td>Mediterranean</td><td>Mediterranean</td><td>Atlantic</td><td>Atlantic</td></tr><tr><td>Notes</td><td></td><td>3</td><td></td><td></td></tr></tbody></table>
<table><caption>Table 1. *Cont.*</caption><thead><tr><th></th><th>O. nicolai<br>(Monterosato, 1884)</th><th>O. paddeui<br>(Bonomolo and Buzzurro, 2006)</th><th>O. purpuroidea<br>(Pallary, 1920)</th><th>O. vazzanai<br>sp. nov.</th></tr></thead><tbody><tr><td>Figures</td><td>3F</td><td>4A</td><td>4B</td><td>1A–G and 4C</td></tr><tr><td>Shell TH (in mm)</td><td>up to 19.74</td><td>up to 15.03</td><td>up to 16</td><td>up to 18.4</td></tr><tr><td>Protoconch</td><td>w: unknown</td><td>w: 1.15</td><td>w: 1.25–1.5</td><td>w: 1.25–1.5</td></tr><tr><td>w: whorls</td><td>m: unknown</td><td>m: smooth with growth lines</td><td>m: unknown</td><td>m: with small granules</td></tr><tr><td>Protoconch</td><td>ga: rounded, slightly scalariform</td><td>ga: slender, not scalariform</td><td>ga: broad, not scalariform</td><td>ga: slender, slightly scalariform</td></tr><tr><td>ga: general aspect</td><td>w: up to 6.5</td><td>w: up to 5.5</td><td>w: up to 5</td><td>w: up to 6</td></tr><tr><td>w: whorls</td><td>cp: from uniformly whitish to light tan</td><td>cp: pale brown with whitish spiral</td><td>cp: light tan with brown blotches</td><td>cp: uniformly pale brown/reddish/orangish, often with a whitish spiral band in median zone (sometimes two), dark spots on ribs</td></tr><tr><td>cp: colour pattern</td><td>or pale brown with a whitish spiral band in median zone (sometimes two)</td><td>bands in median zone (always two but even more)</td><td></td><td></td></tr><tr><td>Teleoconch sculpture of the convex part of the last whorl</td><td>a: 7–9 rounded and nodose ribs, sometimes with 1–2 erratically placed varices</td><td>a: 6–7 low ribs, occasionally with an erratically placed varix</td><td>a: obsolete, with rarely broad, very low ribs</td><td>a: 8–9 rounded and nodose/spinose ribs, sometimes with 1–2 erratically placed varices</td></tr><tr><td>a: axial</td><td>s: 6 low and strong primary cords</td><td>s: 6 low and weak primary cords</td><td>s: 6 high and narrow primary cords and approximately similarly sized secondary cords</td><td>s: 6 nodose and rounded primary cords alternated by smaller secondary cords</td></tr><tr><td>s: spiral</td><td>alternated by smaller secondary cords</td><td>alternated by smaller secondary cords</td><td>t: occasionally present</td><td>t: often present</td></tr><tr><td>t: threads</td><td>t: occasionally present</td><td>t: occasionally present</td><td>t: occasionally present</td><td>t: often present</td></tr><tr><td>Aperture</td><td>ga: moderately large, ovate, pale brown</td><td>ga: narrow and elongate, ovate, shiny white internal colour with brown spiral bands</td><td>ga: large and broad, roundly-ovate, white internal colour with brown spiral bands</td><td>ga: slightly narrow, elongate-ovate, pale brown internal colour</td></tr><tr><td>ga: general aspect</td><td>internal colour</td><td>cl: smooth, weakly erect abapically, adherent adapically</td><td>cl: narrow, smooth, adherent</td><td>cl: smooth, slightly expanded ventrally, erect abapically and adherent adapically</td></tr><tr><td>cl: columellar lip</td><td>cl: narrow, smooth, adherent</td><td>ol: crenulate, erect</td><td>ol: crenulate</td><td>ol: crenulate, erect</td></tr><tr><td>ol: outer lip</td><td>ol: crenulate, erect</td><td>ol: crenulate, erect</td><td>d: 5 weak pairs</td><td>d: 5 strong, rarely one could appear double</td></tr><tr><td>d: denticles</td><td>d: 5 weak</td><td>d: 5 weak</td><td>ID: absent</td><td>ID: absent</td></tr><tr><td>ID: infrasutural apertural denticle</td><td>ID: absent</td><td>ID: absent</td><td>lt: absent</td><td>lt: absent</td></tr><tr><td>lt: labral tooth</td><td>lt: absent</td><td>lt: absent</td><td>lt: absent</td><td>lt: absent</td></tr><tr><td>Radula rachidian cusps</td><td>unknown</td><td>unknown</td><td>unknown</td><td>c: short and thick<br>l: short and thick</td></tr><tr><td>c: central</td><td></td><td></td><td></td><td></td></tr><tr><td>l: lateral</td><td></td><td></td><td></td><td></td></tr><tr><td>Animal general colour pattern</td><td>unknown</td><td>unknown</td><td>unknown</td><td>creamish</td></tr><tr><td>Depth range (in m)</td><td>circalittoral</td><td>80–120</td><td>infralittoral</td><td>50–52</td></tr><tr><td>Distribution</td><td>Mediterranean</td><td>Mediterranean</td><td>Atlantic</td><td>Mediterranean</td></tr><tr><td>Notes</td><td colspan="4">Notes: (1) Houart [25] considered O. erinaceus and O. brevirobusta as different species, whereas Berrou et al. [35] kept them as subspecies. We keep them separated based on MolluscaBase [41]; (2) Taxa previously ascribed to O. edwardsii, O. hispidula, O. ingloria, and O. leukos belong to an unsolved complex of species, that we keep here as "Ocenebra edwardsii" (Payraudeau, 1826) complex" [30]. These taxa are figured below with O. cyclopus (Monterosato, 1884); (3) Ocenebra hybrida is morphologically indistinguishable from O. piantonii. Despite this, we still kept the two taxa separated [30], but our O. hybrida description includes O. piantonii. Ocenebra hybrida is also possibly conspecific with O. baetica (Reeve, 1845), figured below. If so, O. hybrida should be considered a junior synonym.</td></tr></tbody></table>

Notes: (1) Houart [25] considered *O. erinaceus* and *O. brevirobusta* as different species, whereas Berrou et al. [35] kept them as subspecies. We keep them separated based on MolluscaBase [41]; (2) Taxa previously ascribed to *O. edwardsii*, *O. hispidula*, *O. ingloria*, and *O. leukos* belong to an unsolved complex of species, that we keep here as "*Ocenebra edwardsii*" (Payraudeau, 1826) complex" [30]. These taxa are figured below with *O. cyclopus* (Monterosato, 1884); (3) *Ocenebra hybrida* is morphologically indistinguishable from *O. piantonii*. Despite this, we still kept the two taxa separated [30], but our *O. hybrida* description includes *O. piantonii*. *Ocenebra hybrida* is also possibly conspecific with *O. baetica* (Reeve, 1845), figured below. If so, *O. hybrida* should be considered a junior synonym.
<figure><img src="image_5.png" /><figcaption>**Figure 2.** Recent northeastern Atlantic and Mediterranean small species of the genus *Ocenebra* Gray, 1847, with primary cords in the labral varix of the last whorl highlighted (when present): apertural and adapertural views (part 1). Specimens not to scale (sizes in mm as TH × TW). Abbreviations used for spiral sculpture as in Material and Methods. (A–E) *Ocenebra edwardsii* (Payraveau, 1826) complex. (A) *Ocenebra edwardsii* (Payraveau, 1826). Holotype of *Amyclina compacta* Nordsieck, 1968 (SMF 344006, 12.6 × 7.7). (B) *Ocenebrina cyclopus* Monterosato, 1884 (already a synonym of *O. edwardsii*, see Table 1). Syntype (MCZR-M-30033, 13 × 7.45), frontal view after Appolloni et al. [57]. (C) *Ocenebra hispidula* (Pallary, 1904). Syntype (MNHN 1001, 21.9 × 12). (D) *Ocenebra ingloria* (Crosse, 1865). Holotype (MNHN 0993, 18.2 × 8.6). (E) *Ocenebra leukos* (Houart, 2000). Holotype (MNHN 0966, 18.9 × 8.8). (F) *Ocenebra helleri* (Brusina, 1865). Specimen from the closest site to its original description (Mijet Island, Croatia, 60–90 m, 11 × 5.7) (AN private collection).</figcaption></figure>
<figure><img src="image_6.png" /><figcaption>**Figure 3.** Recent northeastern Atlantic and Mediterranean small species of the genus *Ocenebra* Gray, 1847, with primary cords in the labral varix of the last whorl highlighted (when present): apertural and adapertural views (part 2). Specimens not to scale (sizes in mm as TH × TW). Abbreviations used for spiral sculpture as in Material and Methods. (A) *Ocenebra hybrida* (Aradas and Benoît, 1876). Specimen from the closest site to its original description (Isola delle Correnti, Italy, 2 m, 11.5 × 6.5) (AR private collection). (B) Syntype of *Murex baeticus* Reeve, 1845 (NHMUK 1972024, 15.8 × 8.5), a possible senior synonym of *O. hybrida*. (C) *Ocenebra piantonii* (Cecalupo, Buzzurro, and Mariani, 2008). Holotype (MNHM 33490, 10.3 × 6.5). (D) *Ocenebra inordinata* Houart and Abreu, 1994. Holotype (MMF 25429, 19.2 × 10.0). (E) *Ocenebra miscowichae* (Pallary, 1920). Syntype (MNHN 177, 12 × 6.3). (F) *Ocenebra nicolai* (Monterosato, 1884). Syntype (MCZR-M-30034, 19.7 × 11.3), frontal view after Appolloni et al. [57].</figcaption></figure>
<figure><img src="image_7.png" /><figcaption>**Figure 4.** Recent northeastern Atlantic and Mediterranean small species of the genus *Ocenebra* Gray, 1847, with primary cords in the labral varix of the last whorl highlighted (when present): apertural and adapertural views (part 3). Specimens not to scale (sizes in mm as TH × TW). Abbreviations used for spiral sculpture as in Material and Methods. (A) *Ocenebra paddeui* (Bonomolo and Buzzurro, 2006). Holotype (MNHM 29909, 13.2 × 6). (B) *Ocenebra purpuroidea* (Pallary, 1920). Syntype (MNHN 0931, 14.8 × 9). (C) *Ocenebra vazzanai* sp. nov. Holotype (SZN-MOL034, 15.5 × 8.5).</figcaption></figure>

**4. Discussion**

Muricidae in the northeastern Atlantic and Mediterranean have been always considered a relatively speciose family, with about 60 species (excluding the subfamily Coralliophilinae Chenu, 1859), of which 40 occur in the Mediterranean Sea, a number that also includes about 15 endemic taxa [25; authors' data]. Results from recent systematic studies further confirmed this perception [26–30,32,34], and the present paper additionally raises the biodiversity of the genus *Ocenebra* to at least 13 taxa (one of which is a complex, see Table 1). Such a wide adaptive radiation in the northeastern Atlantic–Mediterranean is not entirely unexpected per se, as *Ocenebra* taxa possess a paucispiral protoconch (up to 1.75 whorls) pointing toward an intracapsular development or a very short pelagic phase, which is usually related to low dispersal capability, high speciation rates, and the presence of endemisms [58]. This is also in agreement with recent studies investigating, among the others, the genera *Aplus* De Gregorio, 1885 and *Dendropoma* Mörch, 1861 in the Mediterranean Sea [59,60]. At the same time, it is also worth a mention that the rate of description of new taxa in the northeastern Atlantic and Mediterranean continues to be
remarkably high [28,32,61–65]. However, the majority of the taxa described as new in the last decades were minute shelled taxa (usually about or less than 5 mm) or sea slugs (and thus without shells that can be found even centuries after their death), or were discovered through a combined approach that involves molecular tools, being cryptic or pseudocryptic of common and widespread species. Contrarily to the examples listed above, *Ocenebra vazzanai* sp. nov. is a relatively large species, belongs to a well-studied taxonomic group, and comes from a widely studied biogeographic area such as Italy.

During the last decades, we (F.C., R.H., G.B.) analysed a wide number of muricids from the northeastern Atlantic and Mediterranean (about 20,000 shells and specimens), and found no samples similar to *O. vazzanai* from any other locality than the Messina Strait area. Despite the fact that we were not able to obtain here any molecular data due to the paucity of living samples and objective difficulties in sampling the type locality again, this new taxon has an unmistakable shell morphology which does not even slightly resemble any other known recent or fossil species, and thus, if widespread, it should not have passed unnoticed until now. Overall, this suggests that *O. vazzanai* is presumably a true endemism, or that it lives in a peculiar habitat connected to underwater caves or perhaps dark environments not easily sampled by professional and amateur malacologists. Marine caves are now widely acknowledged for their rich biodiversity, hosting a variety of sciaphilic communities, ranging from coralligenous to semi- and entirely-dark cave assemblages, and are known to host more than 2000 taxa in the Mediterranean Sea, among which there are ~250 molluscan species [66]. Among them, some Mollusca were described and are still known only from these peculiar environments, i.e., the gastropods *Skeneoides digeronimoi* La Perna, 1999 and *Hyalogyra zibrowii* Warén, 1997 and the bivalves *Neolepton discriminatum* Palazzi and Villari, 2001 and *Lucinoma spelaeum* Palazzi and Villari, 2001 [67–69]. Until further evidence, *O. vazzanai* should also be ascribed to this group of species.

In summary, the present paper adds another proof to the fact that even the northeastern Atlantic-Mediterranean is still an understudied biogeographic region prone to the discovery of new species and further highlights the necessity of taxonomic studies on the local biota, despite the long-lasting malacological and zoological tradition.

**Author Contributions:** Conceptualisation, F.C. and G.B.; methodology, F.C. and G.B.; lab work, F.C.; bibliographic researches, F.C., R.H., and G.B.; writing—original draft preparation, F.C. and G.B.; writing—review and editing, F.C., R.H., and G.B.; funding acquisition, F.C. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** Angelo Vazzana (MBMPRC, Italy) provided the material on which the new species was described. Anders Warén (Sweden) provided photos of the radula. Massimo Appolloni and Angela Perullo provided photos from MCZR (Italy). Joao Canning-Clode, Frederico Cardigos, Manuel Conceicao Biscoito, Teresa Mafalda Goncalves Jardim de Freitas Araujo, Fernando Tempera, and Peter Wirtz provided photos from MMF (Azores). Monica Leonardi, Martina Paolini, and Michele Zilioli provided photos from MNHM (Italy). Manuel Caballer Gutiérrez, Virginie Héros, and Philippe Maestrati provided photos from MNHN (France) [Progam RECOLNAT (ANR-11-INBS-0004)]. Amelia MacLellan provided photos from NHMUK (United Kingdom). Sigrid Hof and Ronald Janssen provided photos from SMF (Germany). Andrea Nappo (Italy), Jakov Prkić (Croatia), and Agatino Reitano (Italy) provided photos and/or specimens from their private collections. Three anonymous referees improved the present paper. We are grateful to all of them.

**Conflicts of Interest:** The authors declare no conflict of interest.

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