© Sociedad Española de Malacología Iberus, 28 (1): 91-96, 2010
A new Manzonia (Gastropoda: Rissoidae) from northwes- tern Morocco
Una nueva Manzonia (Gastropoda, Rissoidae) del Noroeste de Marruecos
Serge GOFAS*
Recibido el 10-II-2010. Aceptado el 30-IV-2010
ABSTRACT A new species of the family Rissoidae is described from the upper slope of Northwestern Morocco. Some characters of this species would relate it to the genus Manzonia whereas others are shared with species currently assigned to the genus Alvania (subgenus Alvinia). Some possible diagnostic characters of Manzonia are discussed.
RESUMEN Se describe una nueva especie de la familia Rissoidae, de la parte superior del talud con- tinental del Noroeste de Marruecos. Algunos caracteres de esta especie sugieren su inclu- sión en el género Manzonia, mientras otros se asemejan a especies que se clasifican actualmente en el género Alvania (sugénero Alvinia). Se comentan algunos caracteres posiblemente diagnósticos del género Manzonia.
INTRODUCTION
Small gastropods belonging to the this family recognized as valid for the family Rissoidae are a prominent part of Mediterranean and Northeast Atlantic the littoral, shelf and upper bathyal mol- south to 28º N (CLEMAM database luscan faunas in the Mediterranean,
* Departamento de Biología Animal, Facultad de Ciencias, Universidad de Málaga, E-29071 Málaga, Spain. Correspondence: [email protected]
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Gibraltar, presently known only from The species is tentatively assigned to the two specimens but definitely distinct genus Manzonia, and the definitive char- from those previously known in the area. acters of Manzonia are discussed.
SYSTEMATICS
Genus Manzonia Brusina, 1870
Type species: Turbo costatus J. Adams, 1797, by original designation (= Turbo crassus Kanmacher, 1798; non Turbo costatus von Salis Marschlins, 1793)
Manzonia alexandrei n. sp. (Figs. 1-7)
Type material: Holotype MNHN 22876 (shell, 1,8 × 1.1 mm) from “Balgim” sta. DW57, and 1 paratype MNHN 22877 (specimen, 1.5 × 1.0 mm) from a sample collected in the vicinity of strait of Gibraltar, from fishermen, 1971. Only known from the type specimens. Type locality: off NW Morocco, 35° 42’ N, 06° 35’ W, 548 m. Etymology: The species is dedicated to my son Alexandre
Description. Shell with a moderately towards the adjacent surface of body high spire, adults up to 1.8 × 1.1 mm. whorl; smooth inside. Inner lip rather Protoconch of 1.25 convex whorls, with thin, slightly detached from the preced- a sculpture of six rather flat, beaded ing whorl except in the centre of the spiral cords, narrower than the inter- parietal area. Shell colour white. spaces; the nodes on the cords extend Remarks: This species seems to be towards the interspaces in which they living on hard substrate in rather deep- determine faint axial folds. Teleoconch water, which would explain its rarity, or 1 1 of 2 /4 to 2 /2 convex whorls, angu- difficulty of collection. The specimen lated at a distance abapically from from the strait of Gibraltar was retrieved suture so as to make the whorls shoul- from a large stone riddled with cavities, dered. Axial sculpture of flexuous, together with many specimens of narrow and very elevated folds, highest Alvania zylensis Gofas and Warén 1982 at the shoulder of whorls, fading out and other gastropods. prior to reaching the suture which is not The new species features a combina- at all undulated, and reaching quite far tion of character states which are not towards the abapical surface of the body found together in any of the species whorl. Spiral sculpture of very flat described in the eastern Atlantic or cords, broader than the interspaces, Mediterranean. The protoconch with bearing irregular, very faint grooves nodose spirals differs drastically from the along spiral lines forming irregular pits; pattern seen in most species of Manzonia interspaces with those grooves much with paucispiral protoconch from Mac- more definite, separating ca. 15 raised aronesia (see MOOLENBECKAND FABER, spiral threads; the spiral cords are more 1987) or from the Lusitanian seamounts elevated towards the abapical half of the (see GOFAS, 2007) where the cords, if any, body whorl, below the line prolonging are smooth. It is reminiscent of the kind the suture. The base of the body whorl of protoconch seen in Alvania weinkauffi with a rather strong and elevated spiral Weinkauff, 1868 (see PONDER, 1985, fig. cord, situated very close to a small 102B) and in its sibling Alvania fischeri umbilical chink and separated from the (Jeffreys, 1884) but there, the nodes are rest of the whorl by a distinct spiral even more separated, looking under high depression. Outer lip opisthocline, bent magnification like small patches aligned in its adapical part and thickened exter- over a minute spiral thread and pasted nally by a broad rim sloping gently over the underlying surface.
92 GOFAS: A new Manzonia from nothwestern Morocco
2 100 µm
3 50 µm
1
5 100 µm 6 100 µm
4 7 50 µm
Figures 1-7. Manzonia alexandrei n. sp. 1: holotype from off NW Morocco, 548 m, apertural view (actual size 1.8 mm); 2: protoconch of the holotype; 3: detail of microsculpture of the holotype; 4: paratype from near the strait of Gibraltar, apertural view (actual size 1.5 mm); 5: protoconch of the paratype; 6, 7: detail of microsculpture of the paratype. Figures 1-7. Manzonia alexandrei n. sp. 1: holotipo, frente a la costa NO de Marruecos, 548 m, vista apertural (tamaño real 1,8 mm); 2: protoconcha del holotipo; 3: detalle de la microescultura del holo- tipo; 4: paratipo, cerca del estrecho de Gibraltar, vista apertural (tamaño real 1,5 mm); 5: protoconcha del paratipo; 6, 7: detalle de la microescultura del paratipo.
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8 9 50 µm Figures 8, 9. Details of microsculpture of Manzonia, comparable to Figures 3 and 7. 8: Manzonia crassa (Kanmacher, 1798), specimen from Benalmádena, southern Spain; 9: Manzonia arata Gofas, 2007, shell from Ampère seamount. Figuras 8, 9. Detalles de la microescultura de Manzonia, comparables con las Figuras 3 y 7. 8: Manzo- nia crassa (Kanmacher, 1798), ejemplar de Benalmádena, sur de España; 9: Manzonia arata Gofas, 2007, concha del banco Ampère .
The most similar species with respect shell and the presence of a spiral depres- to characters of the teleoconch may be sion around the base of the body whorl. Manzonia arata Gofas, 2007, described Nevertheless it must be stressed that the from the Ampère seamount off western separation between the genera Morocco, which shares the general Manzonia, Alvania s.l. and Onoba is not at outline and aspect of the spiral sculpture. all clearcut. Manzonia, as currently rec- The latter is nevertheless clearly different ognized, may form a monophyletic in having the ribs protruding against the group around its type species Manzonia suture so as to make it strongly undu- crassa. Its diagnostic character states lated; the completely different proto- (MOOLENBEEK AND FABER, 1987) include conch, keeled with indistinct and smooth (1) the presence of a “duplicate” peris- spirals, may indicate that they are unre- tome i. e. a strong outer rim on which lated. There is also a superficial resem- the sculpture of the outer surface of the blance with Frigidoalvania thalassae body whorl is usually continued, and an Bouchet and Warén, 1993, described from inner rim continuing the inner surface deep water of Bay of Biscay, but the latter of the aperture, (2) the presence of a spi- differs in being much larger and in ral depression and/or stronger spirals having more numerous and less raised on the abapical part of body whorl, and axial ribs. The protoconch of F. thalassae is (3) a peculiar microsculpture where the radically different, being rather conical in larger spirals bear spirally aligned rows shape with faint spiral striae. of minute (ca. 1 µm) pits whereas the in- The generic placement in Manzonia tervening spaces are furnished with is backed by the general build of the minute, raised spiral lamellae, and still
94 GOFAS: A new Manzonia from nothwestern Morocco
more minute axial threads abutting be- should belong to Manzonia rather than tween these. The value of this latter to Alvania, based on shared characters character has been treated as doubtful such as the presence of a duplicated by BOUCHET AND WARÉN (1993: 657) peristome, of stronger spiral cords on The microsculpture seen in Manzonia the abapical part and the radula with alexandrei n. sp. is not as characteristic as numerous cusps on the inner side of the that seen in the type species and in laterals. This view is also supported by many Macaronesian coastal species. It is the fact that Alvinia has a simple trian- nevertheless not structurally different, gular metapodial tentacle like Manzonia, and differs from Manzonia crassa (figure and unlike Alvania s. str. (see PONDER, 8) in that the spiral elements in the 1985: 39) which has a bundle of separate grooves are more closely packed metapodial tentacles. together and the pits are not so neatly The combination of characters seen demarcated. However such a structure in Manzonia alexandrei n. sp. further sup- can be seen to be very similar in Manzo- ports Ponder’s view that some species nia arata, which from other characters which lack the typical Manzonia- can be assumed to be phylogenetically microsculpture may nevertheless be related to Manzonia lusitanica Gofas more closely related to Manzonia than to 2007, M. crispa (Watson, 1897) and to the Alvania s. str. More independent charac- type species. ters, including those based on molecular PONDER (1985: 48) advocated that sequences, are needed to assess the the subgenus Alvinia Monterosato, 1884 value of this morphological character to (with Alvania weinkauffi as type species) be held as diagnostic of Manzonia.
BIBLIOGRAPHY
AMATI B. 1992. On a new species of Manzonia MOOLENBEEK R.G. AND HOENSELAAR H.J. 1989. from Selvagens Islands, (Gastropoda, Pro- The genus Alvania on the Canary Islands and sobranchia, Rissoidae). Publicações Ocasionais Madeira (Mollusca, Gastropoda) part 1. Bul- da Sociedade Portuguesa de Malacología, 16: 9- letin, Zoölogisch Museum, Universiteit van Am- 12. sterdam, 11 (27): 215–228. BOUCHET P. AND WARÉN A. 1993. Revision of OLIVERIO M. 1994. Developmental vs. genetic the Northeast Atlantic bathyal and abyssal variation in two Mediterranean rissoid com- Mesogastropoda. Bollettino Malacologico, sup- plexes. Journal of Molluscan Studies, 60: 461- plement 3: 579–840. 465. GOFAS S. 1990. The littoral Rissoidae and Ana- OLIVERIO M. 1996. Contrasting developmental bathridae of São Miguel, Azores. Açoreana, strategies and speciation in N.E. Atlantic supplement: 97–134. prosobranchs: preliminary analysis. En: Ori- GOFAS S. 2007. Rissoidae (Mollusca: Gas- gin and evolutionary radiation of the Mollusca tropoda) from northeast Atlantic sea- (Taylor, J. ed.), Oxford University Press, pp. mounts. Journal of Natural History, 41 (13-16): 261-266. 779-885 PONDER W. 1985. A review of the genera of the HOENSELAAR H.J. AND GOUD J. 1998. The Ri- Rissoidae (Mollusca: Mesogastropoda: Ri- ssoidae of the Cancap expeditions, I: the ssoacea). Records of the Australian Museum, genus Alvania Risso, 1826 (Gastropoda Proso- supplement 4: 1–221. branchia). Basteria, 62: 69–115. ROLÁN E. 1987. El género Manzonia Brusina, MOOLENBEEK R.G. AND FABER M.J. 1987. The 1870 en el Archipiélago de Cabo Verde. Pub- Macaronesian species of the genus Manzonia. licações Ocasionais da Sociedade Portuguesa de De Kreukel, 23 (1): 1–16, pl. 1; 23 (2-3): 23–31; Malacologia, 9: 27–36. 23 (10): 166–179, pl. 2–3. ROLÁN, E. 1987. Aportaciones al estudio de MOOLENBEEK R.G. AND ROLÁN E. 1988. New los Risoaceos de las Islas Canarias: I. Des- species of Rissoidae from the Cape Verde Is- cripción de tres especies nuevas. Publi- lands (Mollusca, Gastropoda) part 1. Bul- cações Ocasionais da Sociedade Portuguesa de letin, Zoölogisch Museum, Universiteit van Am- Malacología, 8: 1-4. sterdam, 11 (14): 121–126.
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ROLÁN E. AND FERNANDES F. 1990. Tres nuevas VAN AARTSEN J.J. 1981. Manzonia overdiepi, a especies del género Manzonia (Mollusca, new marine gastropoda (Rissoidae) from Ca- Gastropoda) para la costa occidental de nary and Madeira Is. La Conchiglia, 15 (168- Africa. Publicações Ocasionais da Sociedade Por- 169): 6-7. tuguesa de Malacología, 15: 63-68. SEGERS W. AND SWINNEN F. 2002. Manzonia ba- calladoi, a new species from the Madeiran ar- chipiélago. Gloria Maris, 40 (6): 120-125.
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