© Sociedad Española de Malacología Iberus, 34 (1): 83-88, 2016
Notas breves
Moelleriopsis messanensis (Seguenza, 1876), its radula and taxonomic position (Vetigastropoda, Trochoidea, Skeneidae)
Moelleriopsis messanensis (Seguenza, 1876), su rádula y posición taxo- nómica (Vetigastropoda, Trochoidea, Skeneidae)
Luigi ROMANI*,1 & Cesare BOGI**
Recibido el 30-VI-2015. Acceptado el 18-XI-2015
INTRODUCTION
The family Skeneidae W. Clark, 1851 (Seguenza, 1876) and discuss the taxo- is a speciose group of small vetigastro- nomic position of the genus. pods that appears very heterogeneous and probably polyphyletic (WARéN, 1992; BOuCHET & ROCROI, 2005; MATERIALS AND METHODS WIllIAMS & OzAWA, 2006; HICkMAN, 2013). Numerous genera previously in Abbreviations and acronyms: Skeneidae are now provisionally assig- ned to the Seguenzioidea A.E.Verrill, H: maximum height (in mm), 1884 based on molecular and anatomical W: maximum width (in mm), data (WARéN & BOuCHET, 1989; kANO, MNHNP: Muséum national d’Histoire 2008; kANO, CHIkyu & WARéN, 2009), naturelle, Paris, among them Akritogyra Warén, 1992, SEM: scanning electron microscope. Anekes Bouchet & Warén, 1979, Gra- All Tuscan material was obtained nigyra Dall, 1889, Lissotesta Iredale, 1915, from bottom samples trawled by local Moelleriopsis Bush, 1897 and Trenchia fishermen, the French specimen was knudsen, 1964 have Mediterranean dredged in the frame of representatives. The taxonomic position IFREMER/DEPRO 96 project. Shells of Moelleriopsis Bush, 1897 is quite and opercula were examined with a ste- uncertain, as kANO ET AL. (2009) listed it reomicroscope. Images were obtained as a “plausible” member of the Seguen- with a digital photocamera and SEM. zioidea, but did not include it in their The protoconch whorls are counted molecular dataset. Here we present new according to the method of VERDuIN information on Moelleriopsis messanensis (1977).
* Via delle ville 79, 55013 Lammari (LU), Italy, E-mail: [email protected] ** Via Gino Romiti, 37, I-57124 Livorno, Italy, E-mail: [email protected] 1 Corresponding author
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TAXONOMY
Class GASTROPODA Cuvier, 1795 Subclass VETIGASTROPODA Salvini-Plawen, 1980 Superfamily TROCHOIDEA Rafinesque, 1815 Family SkENEIDAE W.Clark, 1851 Genus Moelleriopsis Bush, 1897 Moelleriopsis messanensis (Seguenza, 1876) [Cyclostrema] (Figs. 1, 2)
Material examined: Moelleriopsis messanensis (Seguenza, 1876): 1 specimen, off Gorgona Island (livorno, Italy) 400 m depth, in Francesco Giusti collection (livorno) (Fig. 1 D); more than 100 shells, off Gorgona Island (livorno, Italy), 500–600 m depth, in luigi Romani collection (lucca), Cesare Bogi collection (livorno), Francesco Giusti collection (livorno); 1 specimen, off Capraia Island (livorno, Italy) 550 m depth, in Francesco Giusti collection (livorno); 1 specimen, Gulf of lion (France), DEPRO, station 3, 1129–1193 m depth, 42° 44.5’ N, 004° 29.4’ E, in MNHNP (Fig. 1A–C, E, F).
Description: Shell skeneiform, bearing a serrated strong central cusp depressed, thin, glossy, with rapidly (Fig. 2 B, C). The numerous marginal expanding whorls. Surface smooth teeth decrease in size outwards and are except for 5–7 basal ridges running claw-shaped with a serrated apical part. inside and around the umbilicus and a The innermost marginals have a very dorsal ridge starting at the beginning of strong central cusp and few smaller teleoconch and slowly fading next the 1 lateral cusps, they become smaller and ½ whorl (Fig. 1 A, B, D). Protoconch of the same size moving outwards (Fig. paucispiral of about 0.5 whorl sculptu- 2 D). There is no lateromarginal plate. red with close-set spiral threads and The external morphology of the animal separated from teleoconch by a varix is unknown. (Fig. 1C). umbilicus broad and deep. Distribution: the Holocene range of Opening wide, circular. The average Moelleriopsis messanensis extends from adult shell reaches 2–2.5 mm in diame- the Bay of Biscay to the lusitanian Sea- ter. The shell does not change its outline mounts and the West-Central Mediterra- through various stages of growth. nean Sea (WARéN, 1992; BECk, METzGER Operculum horny, yellowish and trans- & FREIWAlD, 2006). There are very few parent, multispiral with central nucleus records of live-taken specimens in the and narrow growing edge (Fig. 1 D, E). Mediterranean Basin, all from the The radula is more than 5 times as long North-Central Tyrrhenian Sea and the as wide, bilaterally symmetrical, of the Gulf of lion, from 400–1200 m depth rhipidoglossate type, with formula: n - (ARDOVINI & COSSIGNANI, 1999; COSSIG- 4 - 1 - 4 - n. The transverse rows are NANI & ARDOVINI, 2011; present study); more or less sigmoid; the central field empty shells are found between (rachidan + lateral teeth) is not very 350–2500 m depths. wide, the marginal fields are wide with Cyclostrema messanensis was descri- more than 25 teeth each (Fig. 1 F, 2 A, bed by G. Seguenza (1876) as a fossil B). The rachidian tooth is large, subtra- from the Pliocene of southern Italy but pezoidal, with a wide base laterally never illustrated. The type material is expanded, crossed by a horizontal supposedly lost (lA PERNA & D’AB- central ridge. The cutting edge is equip- RAMO, 2010) but three shells were subse- ped with 13–17 cusps, the central cusp quently found in a collection by is much larger than lateral ones (Fig. 2 Seguenza in the Geological and Paleon- C). The lateral teeth, increasing in size tological Museum of Florence univer- outwards, have a curved base, a sity (BERTOlASO & PAlAzzI, 2000), thus straight shaft and bent cutting edges confirming the identity of the species.
84 ROMANI & BOGI: Moelleriopsis messanensis, its radula and taxonomic position
A B
D
C 200 µm
500 µm E F
Figure 1. Moelleriopsis messanensis. A–C, E, F: Gulf of Lion, H 1.52 mm, W 2.01 mm. A: frontal view; B: apical view; C: protoconch; E: operculum, diameter 1.08 mm; F: radula. D: off Gorgona Island, H 1.05 mm, W 1.50 mm, frontal view. Figura 1. Moelleriopsis messanensis. A–C, E, F: Golfo de León, H 1,52 mm, W 2,01 mm. A: vista frontal; B: vista apical; C: protoconcha; E: opérculo, diámetro 1,08 mm; F: rádula. D: frente a la isla de Gorgona, H 1,05 mm, W 1,50 mm, vista frontal.
DISCUSSION
The genus Moelleriopsis Bush, 1897 sabysssicola is characterized by spiral was created for Moelleriopsis abyssicola keels running on the smooth whorls (1 Bush, 1897 a deep water skeneiform adapical and 4 periumbilical). This from the North-Eastern Atlantic Ocean, sculpture is very similar to that of known only from an incomplete empty Cyclostrema messanensis, which induced shell (BuSH, 1897: 138). Moelleriopsi- WARéN (1992) to consider the two
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A 25 µm B 20 µm
C 10 µm D 20 µm Figure 2. Moelleriopsis messanensis, radula, Gulf of Lion. A: whole view; B, C: partial views of central and lateral teeth; D: marginal teeth. Figura 2. Moelleriopsis messanensis, radula, Golfo de León. A: vista general; B, C: vistas parciales de los dientes central y laterales; D: dientes marginales.
species congeneric even if no anatomical species and M. messanensis, though details were known at that time. Other having somewhat similar shells, display skeneiform gastropods, both recent and completely different radular and oper- fossil, where also assigned to Moelleriop- cular patterns so cannot be regarded as sis only on conchological grounds, congeneric or even confamiliar. Instead (WARéN, 1992; HASEGAWA & OkuTANI, the radula of M. messanensis is very 2011; ENGl, 2012). The World Register of similar to that of Skenea basistriata (Jef- Marine species accepts nine Recent freys, 1877). species of Moelleriopsis (BOuCHET & The use of shell morphology to GOFAS, 2014), to which should be added assess the phylogenetic relationships of unidentified species reported by WARéN skeneiforms is not reliable, as concholo- & BOuCHET (1989), WARéN (1992), HASE- gical homoplasy is quite common in GAWA (2005) and BECk ET AL. (2006), and these small gastropods. Combined con- two fossil species (TABANEllI, 1991; chological, radular, anatomical and lOzOuET, 1999). molecular criteria must be used for this WARéN (1992), in his revised diagno- purpose. Since Moelleriopsis abyssicola is sis of Moelleriopsis, included radular unknown anatomically and the characters based on an undescribed holotype and only known specimen species from the Indian Ocean having a lacks a protoconch, it is not possible to radula of the “seguenzioid” type. This resolve this conflict definitely, but,
86 ROMANI & BOGI: Moelleriopsis messanensis, its radula and taxonomic position
pending the availability of new material MNHNP provided the French material. for anatomical examination, it is reaso- Giovanni Repetto, Attilio Pagli and nable to provisionally place Moelleriopsis kazunori Hasegawa provided biblio- Bush, 1897 in the family Skeneidae graphic assistence. Sincere thanks are (Warén, pers. comm.). due to Stefano Bartolini for digital pho- tographs, to Anders Warèn for the SEM images and for useful exchange of views ACKNOWLEDGEMENTS and advices, to Enzo Campani for reading the manuscript. Harry G. lee The authors are grateful to Francesco contributed the English revision of the Giusti for the loan of material, the manuscript and made other suggestions.
BIBLIOGRAPHY
BECk T., METzGER T. & FREIWAlD A. 2006. HICkMAN C.S. 2013. Crosseolidae, a new fa- Biodiversity inventorial atlas of macro- mily of skeneiform microgastropods and benthic seamount animals. Eu-ESF project progress toward definition of monophyletic OASIS, 126 pp. Oceanic seamounts: an Skeneidae. American Malacological Bulletin, integrated study; EVk2-CT-2002-00073, 31 (1): 1–16. downloaded at
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WATSON R. B. 1886. Report on the Scaphopoda WIllIAMS S. T. & OzAWA T. 2006. Molecular and Gasteropoda collected by H.M.S. Cha- phylogeny suggests polyphyly of both the llenger during the years 1873–1876. Reports turban shells (family Turbinidae) and the su- of the scientific results of the voyage of H.M.S. perfamily Trochoidea (Mollusca: Vetigas- “Challenger”, Zoology 15 (part 42): 1–756, pl. tropoda). Molecular Phylogenetics and Evolu- 1–50 and Caecidae pl. 1–3. tion, 39: 33–51.
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