15Bollettino della Società Paleontologica Italiana, 48 (1), 2009, 15-19. Modena, 15 maggio 2009

ISSN 0375-7633

INTRODUCTION

Garilli & Messina (2006) recently discussed theoccurrence of the eulimid gastropod genus ChileutomiaTate & Cossmann in Tate, 1898 in the Pliocene to RecentMediterranean area and described a possible new species,reported as Chileutomia (?) sp., from the Pliocene ofNorth Italy (Emilia Romagna, Campore). In the presentpaper we rediscuss the systematic attribution of this taxonon the basis of new well preserved shells from the samearea and a new species of the family Aclididae isdescribed.

MATERIALS AND METHODS

The study material consists of six shells, collected inthe last two decades by one of us (L.B.) from the Pliocenesediments of Emilia Romagna, Northern Italy. Inparticular, five shells (L. Bertolaso collection) wererecovered from the Lower Pliocene (Piacenzian) clayeybeds cropping out at the Campore quarry (SalsomaggioreTerme, Parma, N Italy), the same locality where thebroken shell of Garilli & Messina (2006) was collected(see Raffi & Taviani, 1985; Bianucci, 1997; Bertolaso &Palazzi, 1997, and Channel et al., 1994 for geographicallocation, paleoecological and stratigraphic informationon this outcrop). One shell (L. Bertolaso collection) wasrecovered from the clays cropping out near Ca’ de Fii,about 3.5 Km N of Castellarano (Reggio Emilia). As faras we are aware, no detailed stratigraphic information isavailable for the deposit of Ca’ de Fii which belongs to

the Lower Pliocene-Lower Pleistocene “Argille Azzurre”(Vai, 1988) or “Argille di Lugagnano” (Arrigoni et al.,1965) formation (Losacco et al., 1964; Cita et al., 2006;Bosellini et al., 2003). The lower circalittoral toepibathyal molluscan assemblage from this outcrop iscomparable with that from the Piacenzian of Campore(as described by Raffi & Taviani, 1985), though the formerhas a lower diversity. Anyway a prudent approach suggeststhat an Early to early Middle Pliocene age could beassigned to the deposit of Ca’ de Fii, as supported by theoccurrence of Mitrella compta (Bronn, 1831) and,subordinately, Cerithiella genei (Bellardi & Michelotti,1840) (see Marasti & Raffi, 1976 and 1977 for theirstratigraphic meaning). Actually these species arerepresentative of the Mediterranean Upper Neogenemolluscs of tropical affinities, whose extinction occurredin the early Piacenzian, approximating the MammothSubchron (Raffi & Marasti, 1982).

Four shells (holotype and paratypes 1-3) were studiedby the scanning electron microscope using a Philips XL30 ESEM. Particular attention was given to protoconchand teleoconch microsculpture as possible taxonomiccharacters at species level. The number of protoconchwhorls was counted according to Verduin’s method(1977).

SYSTEMATICS

The systematics of the family Aclididae, as well asother supposed Ptenoglossa (see Collin, 2002 and 2004for a short overview on this suborder), is still uncertain.

Description of Aclis aurisparva n. sp. (Gastropoda, Aclididae)from the Pliocene of Emilia Romagna (N Italy)

Luca BERTOLASO & Vittorio GARILLI

L. Bertolaso, Via Manzotti 35, I-42015 Correggio (Reggio Emilia), Italy.V. Garilli, APEMA Research and Educational Service, Via Alla Falconara 34, I-90136 Palermo, Italy; vittoriogarilli@apema.eu

KEY WORDS - Gastropoda, Aclididae, Aclis new species, Pliocene, N Italy.

ABSTRACT - A new species of the family Aclididae is described from the Pliocene of Emilia Romagna (Northern Italy) as Aclis aurisparvan. sp. This species was formerly reported as Chileutomia (?) sp. (family Eulimidae) but the finding of new, well preserved material has alloweda correct systematic placement. This new species and other similar Mio-Pliocene congeners, with apparently-polished-shells (Italian andTurkish material, under study) close to the A. attenuans - A. walleri group, allow us to hypothesise that the Aclis species with smooth shells (orwith a spiral microsculpture) from the Mediterranean Upper Neogene are more numerous than expected.

RIASSUNTO - [Descrizione di Aclis aurisparva n. sp. (Gastropoda, Aclididae) dal Pliocene dell’Emilia Romagna (N Italia)] - Sulla base dinuovi ritrovamenti di materiale ben preservato, proveniente dal Pliocene (presumibilmente Zancleano-primo Piacenziano) dell’Emilia Romagna,viene ridiscussa la posizione sistematica del taxon precedentemente riportato come Chileutomia (?) sp. (famiglia Eulimidae). Tale taxon, quidescritto come Aclis aurisparva n. sp., è caratterizzato da una minuta ornamentazione spirale sulla teleoconca e da un marcato processo labialevaricoso il quale forma una caratteristica espansione del labbro esterno, particolarmente sviluppata negli esemplari subadulti. Aclis aurisparvan. sp. è confrontabile con A. attenuans e A. walleri, rispettivamente viventi in Mediterraneo ed Atlantico orientale, e con alcune specie fossilicongeneriche ad esse particolarmente affini (in studio). La descrizione di questo taxon, e l’osservazione di altro materiale inedito, utilizzatoper confronto, consentono di suggerire che le Aclis spp. lisce (o provviste di una fine microscultura spirale) del Neogene mediterraneocostituiscano un gruppo più numeroso di quanto desumibile dalla letteratura malacologia.

16 Bollettino della Società Paleontologica Italiana, 48 (1), 2009

According to Warén (in Giannuzzi-Savelli et al., 1999,p. 7) most part of the genera and species traditionallyincluded in this family could be placed in theHeterobranchia, as suggested by some data from livingspecies. For the moment being, we maintain the placementin the Ptenoglossa, following the systematic proposedby Giannuzzi-Savelli et al. (1999).

Class GASTROPODA Cuvier, 1797Order NEOTAENIOGLOSSA Haller, 1882

Suborder PTENOGLOSSA Gray J.E., 1853Superfamily JANTHINOIDEA Lamarck, 1810

Family ACLIDIDAE Sars G.O., 1878Genus Aclis Lovén, 1846

Type species - Alvania supranitida Wood S.V., 1842by monotypy.

Aclis aurisparva n. sp.(Pl. 1, figs. 1-15)

2006 Chileutomia (?) sp. GARILLI & MESSINA, pp. 198-199, Fig.1c, Pl. 1, figs. 6-7, 9-10.

Description - Shell conical, macroscopicallypolished, rather thin and minute, 2.5 mm in height and0.95 mm in width (in holotype). Protoconch multispiral,conical and elongated, 0.6 mm in height (paratype 1), witha rather immersed nucleus and slightly convex whorls.Protoconch I consisting of little less than one smoothwhorl; protoconch II formed by about 2.3 whorls, with

numerous growth scars running from suture to sutureand irregularly spaced. Growth scars sinuous,prosocirte and opisthocirte in the abapical and in theadapical portion of the whorl respectively. Protoconch/teleoconch boundary marked by a sinuous scar.Teleoconch formed by 2.5-5 strongly convex whorlsoften bearing expanded varicose labial processes andforming a moderately pronounced subsutural ramp inthe area near the varicose processes. Labial processesare evident from the penultimate whorl and may bewell to moderately expanded adapically and clearly half-detached, or reduced to very few detached prominentscars. Angular distance between them of about 90° and180°. Teleoconch microsculpture consisting ofnumerous (35-40 on the penultimate whorl of paratype2), fine and moderately raised spiral threads, somewhatdiscontinuous, becoming coarser and more closelyspaced on subsutural area. Teleoconch is crossed byirregularly spaced, moderately marked and slightlycurved, opisthocline growth lines, and few rough andvery irregular raised scars. Sutures slightly inclined andmoderately deep. Last whorl making up little more thanone half of the total shell height. Aperture ovate, higherthan broad, extended in its lower part, making up abouttwo thirds of last whorl height and one third of totalshell height. Outer lip flattened in the lower part, andfolded in the remaining part, where a sort of slightconcavity occurs along the edge. This concavityappears deeper on the uppermost area, close to thecontact with the body whorl, where the lip expansionmay form a short wing-shaped extension, making theperistoma ear-shaped. Inner lip curved and with a thinexpansion which is narrower along the columellar side.

EXPLANATION OF PLATE 1

figs. 1-5 - Aclis aurisparva n. sp. Pliocene of Campore, Salsomaggiore Terme, Parma, N Italy.1 - Protoconch of paratype 1 (MZB45638), showing the sinuous scars.2 - Protoconch of paratype 1 (MZB45638), showing the sinuous scars, the protoconch I/protoconch II (black arrow) and

protoconch/teleoconch boundaries (white arrows).3 - Protoconch of paratype 1 (MZB45638), showing the sinuous scars and protoconch/teleoconch boundary (white

arrows).4 - Protoconch of paratype 2 (MZB45639), showing the sinuous scars.5 - Protoconch of paratype 1 (MZB45638), showing the sinuous scars and the protoconch I/protoconch II boundary

(black arrow).

figs. 6-7 - Aclis aurisparva n. sp. Holotype (H = 2.5 mm, MZB45642).6 - Apertural view of the shell.7 - Detail of teleoconch microsculpture.

figs. 8-10 - Aclis aurisparva n. sp. Paratype 1 (H = 1.3 mm, MZB45638).8 - Apertural view of the shell.9 - Dorsal view of the shell.10 - Detail of the upper part of the outer lip.

figs. 11, 13-15 - Aclis aurisparva n. sp. Paratype 2 (H = 1.2 mm, MZB45639). Pliocene of Campore, Salsomaggiore Terme, Parma, N Italy.11 - Detail of the umbilical chink.13 - Apertural view of the shell.14 - Dorsal view of the shell.15 - Detail of the spiral microsculpture.

fig. 12 - Dorsal view of paratype 3 (H=1.3 mm, MZB45640), Pliocene of Ca’ de Fii, Castellarano, Reggio Emilia, N Italy.

Scale bars = 100 μm in figs. 1-4, 10-11; = 50 μm in figs. 5, 7, 15.

17L. Bertolaso, V. Garilli - A new Pliocene aclidid gastropod Pl. 1

18 Bollettino della Società Paleontologica Italiana, 48 (1), 2009

Narrow umbilical chink, partially covered by theexpansion of the inner lip.

Type material - Holotype and paratypes 1-4 arehoused in the Museo di Zoologia of the University ofBologna (MZB), paratypes 5 and 6 are housed in theDipartimento di Geologia e Geodesia of the Universityof Palermo (DGUP), coll. V. Garilli.

Holotype (2.5 mm x 0.95 mm, catalogue numberMZB45642), paratype 1 (1.3 mm x 0.6 mm, cataloguenumber MZB45638), paratypes 2 (1.2 mm in height,catalogue number MZB45639), 4 (1,2 mm in height,catalogue number MZB45641), 5 (catalogue n°CAPA001/536, ex F75A coll. S. Palazzi, the broken shellillustrated by Garilli & Messina, 2006, pl. 1, figs. 6-7, 9-10 and Fig. 1c) and 6 (1.05 mm x 0.5 mm, cataloguenumber DGUP CAPA002/537) are from the Pliocenedeposit at the Campore quarry, Salsomaggiore Terme,Parma, Emilia Romagna, North Italy; paratype 3 (1.3 mmin height, catalogue number MZB45640) is from thePliocene clays cropping out at an abandoned quarry nextto Ca’ de Fii, about 3.5 Km N of Castellarano, ReggioEmilia, North Italy (44°32’16”N 10°45’00”E).

Type locality - The Pliocene bluish clay cropping outin the Campore quarry, Salsomaggiore Terme, Parma,North Italy.

Etymology - After the Latin auris (ear) and parva(small), referring to the ear-shaped peristoma, moreclearly shown by paratype 1.

Distribution - Aclis aurisparva n. sp. is only knownfrom the Pliocene (possibly Zanclean to earlyPiacenzian) lower circalittoral to epibathyal depositsfrom Campore and Ca’ de Fii, Emilia Romagna (N Italy).

Comparisons and remarks - The general shell shape,the characters of protoconch and aperture, and the finespiral sculpture exclude the placement of this species inChileutomia Tate & Cossmann in Tate, 1898. This genusis characterized by more markedly varicose shell with analmost pyriform aperture provided with a sinus in the upperpart of the outer lip. Admittedly, the characteristicincremental scars (also forming varicose labialprocesses) occurring in Aclis aurisparva n. sp. are quitecommon in the families Muricidae, Cymathiidae andEpitoniidae, and even vetigastropods show similarprocesses (A. Warén, 2008, personal communication).Expanded labial processes also occur in the genusHoplopteron Fischer, 1876, tentatively assigned toEulimidae (Warén, 1984). However this genus (asillustrated by Warén, 1984, fig. 108) shows markedlyexpanded varices, its aperture is almost pyriform, and theteleoconch whorls lacks ornamentation and are lessconvex, particularly when comparing with the Eocenetype species of Ptereulima (a synonym of Hoplopteronaccording to Warén, 1984, p. 68, fig. 161).

The general teleoconch and protoconch shape, and theovate aperture of the new species indicate a strong affinitywith Aclididae, though all these characters may also occurwith similar patterns in the families Epitoniidae andEulimidae (A. Warén, 2008, pers. comm.). As an

example, the Mediterranean Aclis attenuans Jeffreys,1883 and the Atlantic A. walleri Jeffreys, 1867 have ageneral shell shape very close to that of Aclis aurisparvan. sp., with which they also share the expansion of thelower part of the aperture, the shape of the umbilicusand the occurrence of numerous irregular scars, thelast two features being common in the genus Aclis (seeBouchet & Warén, 1986, fig. 726-727 and 730-732for Recent shells of A. attenuans and A. walleri and DiGeronimo & La Perna, 1997, pl. 4, fig. 10 for PleistoceneA. attenuans). Also the sinuous scars occurring onprotoconch II are very similar to that shown by A. walleri.The extremely fine spiral striation shown by A.aurisparva n. sp. is another significant character. Thismicrosculptural pattern is not found in the Epitonidae andscarcely represented in the Eulimidae, but seemswidespread in the family Aclididae: e.g. Aclis crassilirata(Cossmann, 1900), Eocene of France, Bois Gouët; A.carolinensis Bartsch, 1911, North Carolina, Recent; A.thesauraria Melvill, 1904, Gulf of Oman, Recent (A.Warén, 2008, pers. comm.). Also the supposed AclididaeHemiaclis hyalina (Watson, 1880), from the north-eastern coasts of Brazil (Mello et al., 2003), shows asimilar sculpture (see Mello et al., 2003, fig. 1e). A spiralmicrosculpture similar to that of Aclis is present in someeulimids, such as Pelseneeria Koeler & Vaney, 1908 (seeP. striata Bouchet & Warén, 1986, figs. 994-995),whereas other genera of the same family (e.g.Amamibalcis Kuroda & Habe, 1950, Annulobalcis Habe,1965, Arcuella Nevill, 1874 and Trochostilifer Warén,1980) have different, much more pronounced spiralsculpture (see Warén, 1984 and Warén et al., 1984).

Aclis aurisparva n. sp. shows a remarkable rangeof variation in shape. Whereas the paratype 1 shows amore slender, elongate shell, paratypes 2 and 3 havebroader shells. Following Bouchet & Warén (1986),this variation, rather common in the genus Aclis, islikely due to sexual dimorphism (see Bouchet & Warén,1986, pp. 726-727 and 730-732 for A. attenuans andA. walleri and Giannuzzi-Savelli et al., 1999, figs. 110and 111 for A. attenuans and A. gulsonae (W. Clark,1850)). We noted the same variation among someMediterranean Mio-Pliocene (from North Italy andSouth Turkey, L. Bertolaso collection) apparentlysmooth Aclis spp., more or less related to the A.attenuans-A. walleri group or with a somewhatangulated base.

CONCLUDING REMARKS

Chileutomia miranda (Dautzenberg, 1925) remainsthe sole known representative of its genus in the Plioceneto Recent Mediterranean area, whereas Chileutomia (?)sp. of Garilli & Messina (2006) is proved to be an aclididspecies, herein described.

Aclis aurisparva n. sp. is well characterized by itsear-shaped peristoma and the presence of amicrosculpture, and cannot be confused with congeners.It is noteworthy that among the recorded Aclis speciesfrom the Mediterranean Pliocene (Tabanelli, 1997, listed14 Plio-Pleistocene species from Italy) only A.attenuans (including the Mediterranean citation of A.

19

walleri), A. brugnoniana De Stefani & Pantanelli, 1879and A. gulsonae var. subappenninica Sacco, 1891 (thelast two are poorly known, needing to be revised) have,at least apparently, no spiral sculpture. However theoccurrences of the Pliocene A. aurisparva n. sp. andthe above mentioned Mio-Pliocene undetermined Aclisspp. (our material from Italy and Turkey, under study)allows to suppose that more (macroscopically) polishedaclidid species lived in the Mediterranean area duringthe Neogene.

ACKNOWLEDGMENTS

We would like to thank Anders Warén (Swedish Museum ofNatural History, Stockholm) for the useful discussion and commentson the systematic placement of Aclis aurisparva n. sp. He alsoreviewed the submitted manuscript. Thanks are also due to LucaGalletti (APEMA, Research and Educational Service, Palermo) forthe help in providing SEM images. We are grateful to Marina Cantelliand Bruno Sabelli (Museo di Zoologia, University of Bologna) whoprovided catalogue numbers. Rafael La Perna (Dipartimento diGeologia e Geofisica, University of Bari) reviewed the manuscriptand provided valuable comments.

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Manuscript received 06 May 2008Revised manuscript accepted 14 October 2008

L. Bertolaso, V. Garilli - A new Pliocene aclidid gastropod