Two new species of the family Cornirostridae (Gastropoda: Heterobranchia: Valvatoidea) from Senegal (West Africa)

2008·2.4 MB·

by  Emilio Rolán

E. ROLÂN & F. RUBIO Novapex9(4): 155-160, 10 novembre 2008
Two new species ofthe family Cornirostridae
(Gastropoda: Heterobranchia: Valvatoidea) from Sénégal (West Africa)
ROLAN
Emilio
Canovas del Castillo, 22
36202 Vigo, Spain
E-mail: emiliorolanfainicia.es
Federico RUBIO
Pintor Ribera, 4-16a
46930 Quart de Poblet, Valencia
Spain
KEY WORDS. Cornirostridae. Tomura, West Africa. Sénégal, new species.
ABSTRACT. Two new species of the genus Tomura collected in sédiment from Dakar are
described and compared with the species previously known from West Africa. A list ofthe species
ofCornirostridae is compiled with indication ofthe distribution area.
INTRODUCTION
The genus Tomura was described by Pilsbry & spécimens were shown in a table, and the generic and
McGinty (1946) as a subgenus of Vitrinella due to the family diagnosis were discussed. The shells and soft
great similarity in the characters oftheir shells. They parts ofthe family were redefined: "small (<2.3 mm)
figured the animal of the new species Tomura valvatoideans with (almost) smooth skeneiform
bicaudata with an anteriorly bifurcated foot. teleoconchs of 2-3 more-or-less convex whorls and
Moore (1964) doubted the placement ofthis genus simple peristome, and (weakly) sinistral protoconchs
in Vitrinellidae because ofthe scarce présence ofthe coiling around the same axis (this larval hyperstrophy
cephalic tentacle represented in the original figure might not be expressed if only protoconch I
(Pilsbry& McGinty, 1946). (embryonic shell) is présent, e.g., Noerrevangia);
Ponder (1990: 554) introduced the family snout long, with two tentacle-like oral lobes; radula
Cornirostridae with two monotypical gênera: with 7-9 teeth per row including 2-3 partly
Cornirostra (type species Microdiscula pellucida overlapping latéral teeth. and rachidian with highly
Laseron. 1954) and Tomura [type species Vitrinella developed latéral support; foot with propodial and
{Tomura) bicaudata Pilsbry & McGinty, 1946], giving metapodial extensions, cleft anteriorly and posteriorly;
no formai diagnosis of the gênera, but showing single right palliai tentacle: bipectinate. basally
numerous morphological différences and similarities attached gill; hermaphroditic reproductive System with
with freshwaterValvatidae. cephalic pénis".
Warén. Gofas & Schander (1993: 2) presented the The first species ofthe genus Tomura recorded for
morphologie characters of Cornirostridae, discussing the North African coast by Rubio-Salazar (1990) was
and correcting the radular characteristics of Oxystele depressa Granata, 1877 (from which
Skeneopsis pellucida (Laseron, 1954) and Tomura Tharsiella tinostomoides Fekih & Gougerot, 1977 is a
bicaudata, assigning Skeneopsis pellucida to the synonym). It is a typically Mediterranean species,
genus Xenoskenea Warén & Gofas, 1993. which is Rabat (Morocco) being its southernmost record.
included in the family Hyalogyrinidae Warén & Fukuda & Yamasita (1993) described two new species
Bouchet, 1992. from Japan.
Rubio & Rolân (1998) described Tomura There were no new additions to the genus until
xenoskenoides from Yucatan, Mexico, presenting Rolân & Rubio (1999) described Tomura abscondita
anatomical and radular information. as a new species from the Cape Verde Archipelago.
&
Bieler. Bail Mikkelsen (1998) described In sédiment samples collected in récent years by
Cornirostra floridana from Florida Cays (USA), the senior author, several shells of two unidentified
adding a detailed anatomical study. The anatomical species of Tomura were found. Being différent from
and morphological characters of the shell of the the previously known species. they are described as
animal ofthe seven species known from live taken new for science.
155
I Roi VN&F. Ri Hlii Two new species ofCornirostridae
xhhiohuions collections: I (Fig. 5) AMNH. 1 BMNH 20080187, 1
(Fig. 4) USNM I 1 12470. 1 ZSM. I CJH. 2 (Figs. 2-4.
\\l\ll American Muséum ofNaturel History, New 6-9) MlINS. ail of them from the type locality; 2
MNHN
York, l SA. 20845. l'rom hors Coast.
BMNH: I lie Naturel Historj Muséum, London, UK.
\III\S: Museo de Historia Naturel "Luis Iglesias", Type locality. Sénégal. Dakar Bay. between 15 and
Santiago de Compostela, Spam. 40 m.
\1\1IV Muséum national d'Histoire naturelle. Paris. Etymology. The spécifie naine refers to the almost
France. spherical shape ofthe shell.
MNCN: Museo Nacional de Ciencias Naturales,
Madrid. Spam. Description. Shell (Figs 1-9) small, rather sturdily
MCZ: Muséum ofComparative Zoology, Cambridge. built, almost spherical, subovate in outline, weakly
U.K. depressed. quite smooth, slightly glassy, white. The
I SNM: National Muséum oï Natural History. upper surface is convex. The protoconch (Figs 10-11),
Washington D. C. USA. hyperstrophic, small, with 3A of whorl, apparently
ZSM: Zoologisehe Staatssammlung, Mûnchen, smooth; its diameter is ofabout 190 um. Protoconch I
Germany. partially visible, separated from the Protoconch II by a
CJH: collection o\~ José Maria Hernândez, Gran strong axial rib. The teleoconch has between 2.15-2.25
Canaria. whorls in adult spécimens. The spire increases
uniformly. The suture is clear but not deep and a slight
SYSTEMATICS
dépression appears below it. The aperture (Fig. 1) is
HETEROBRANCHIA almost circular, slightly pyriform; the columella
Subclass
VALVATOIDEA strongly curved, a little angled and opisthocline. There
Superfamily Gray, 1840
Family CORNIROSTRIDAE Ponder. 1990 is a short callus which totally covers the umbilicus.
Genus Tomura Pilsbry & McGinty. 1946 The apertural border is sharp and the peristome
continuous, a little wider at the base. The surface of
&TypMecGispnetcyi,es:194Vi6trbiynemlolano(tTyopmyu.ra) bicaudata Pilsbry the shell is covered with numerous very fine spiral
striae, and axial growth Unes which foim some folds
& near the base. Under high magnification there can be
Diagnosis (after Pilsbry McGinty, 1946). Shell
orbicular. depressed, polished, last vvhorl rounded at seen that the spiral striation is formed by very small,
impressed, irregularand poorly limited cords (Figs 12-
the periphery: ombilical région covered with a large,
13) which are more évident on the upper part of the
liât callus; aperture transverse, rounded, greatly
whorls.
produced and elongated, ending anteriorly in a slightly
Holotype: height 0.84 mm, width 0.94 mm.
canaliculate point; inner lip smooth, callous, not
emarginate or truncate anteriorly; outer lip thin, Dimensions ofthe largest spécimens 1.0 x 1.1 mm.
Soft parts unknown.
simple, not marginated or reflected.
Remarks. According to Warén et al. (1993), the Remarks. Tomurasphaerica differs from T. depressa,
species ofCornirostridae are nearly similar to those of by its smaller size, the more globose shape ofits shell
Vitrinellidae in shell characters. Some species, like and by having its entire surface covered by spiral
Tomura depressa can be recognized as belonging to threads.
Heterobranchia, by their heterostrophic larval shell, It can be separated from T. abscondita because the
but a radular study is required to confirm its family callus formed by the thickening of its internai lip
placement. This character is more évident in some completely covers the umbilicus.
species of the genus Tomura (as T. depressa and T. It differs from T. bicaudata by its sculpture and the
ascondita) and less so in T. bicaudata. lack ofa periumbilical cord.
Tomurasphaerica sp. nov. Tomura umbiliobsessa sp. nov.
Figs 1-13 Figs 14-23
Type material. Holotype (Fig. 1) deposited in the Type material. Holotype (Fig. 14) deposited in the
MNCN MNCN
15.05/47.523. Paratypes in the following 15.05/47.524. Paratypes in the following
Figures 1-13. Tomura sphaerica sp. nov., Dakar, Sénégal.
1. holotype. 0.94 mm (MNCN 15.05/47.523); 2-3. paratypes, 1.09, 0.98 mm (MHNS); 4. paratype, 1.05 mm
(USNM); 5. paratype, 1.03 mm (AMNH); 6-9. paratypes, 1.10, 1.05, 0.96, 1.01 mm (MHNS); 10-11.
protoconch; 12. microsculpture on the shell on its dorsal part; 13. microsculpture in ventral part.
156
E. ROLÂN& F. RUBIO N0VAPEX9(4): 155-160, 10 novembre 2008
157
w\
I ROI I Ki lilo Two ncu species ofCornirostridae
collections: I (Fig. 16) \\l\ll: 1 BMNH 20080188; I rom F sphaerica, for being less globose, having an
I \l\ll\ 20S44; I USNM II 12469; I /S\l; 3 ( JH open umbilicus and small pits in the microsculpture.
and4(l igs 17-20) \lll\s. AH frornthetype locality.
Discussion
4l0\mpe. locality. Sénégal, Dakar Bay, between 20 and The species known in the family Cornirostridae are
the following:
Etymology. rhe spécifie oame is formed by the Cornirostra pellucida (Laseron, 1954)-
fusion ofthe two Latin words, umbilicus and obsessa
Mediterranean.
"which makes blockade", alluding to the partial Cornirostra floridana Bieler & Mikkelsen, 1998-
obstruction ofthe umbilicus by the callus. Florida Keys, USA.
Description. Shell (Figs 14-20) small, sturdily built. Tomura bicaudata (Pilsbry & McGinty, 1946)-
depressed, smooth, not glassy, dorsally with a circulai" Florida Keys, USA.
outline, whitish. The hyperstrophic protoconch (Fig. Tomura xenoskenoides Rubio & Rolàn, 1998-
21 ), is small with about one apparently smooth whorl, Yucatân, Mexico.
with a diameter of about 160 uni. The teleoconch is Tomura depressa (Granata.1877)- Mediterranean Sea,
about 2.25 whorls in adult spécimens. The last whorl W. Africa.
is regularly convex and the spire is only very slightly Tomura abscondita Rolàn & Rubio, 1999- Cape
elevated. The suture is évident but shallow. The Verde Archipelago.
aperture is almost circulai", the columella is regularly Tomurasphaerica spec. nov.- Sénégal.
curved. It spreads both towards the base and the Tomura umhiliobsessa spec. nov.- Sénégal.
umbilicus. more noticeably in mature spécimens. The Tomura yashima Fukuda & Yamashita, 1997- Seto
umbilicus is not covered. being limited by a prominent Inland Sea, Japan.
told ofthe widened columella. The apertural border is Tomura himeshima Fukuda & Yamashita, 1997- Seto
narrow except in the place of the two émargements. Inland Sea, Japan.
The external surface (Figs 22-23) ofthe shell, seems Noerrevangia fragilis Warén & Schander, 1993-
smooth, but when magnification it becomes obvious Faroe Islands.
that it is totally covered with small threads. more
évident on the lower part ofthe shell, with pits in the Hyalogyrinidae
intervais. Thèse threads are crossed by growth Unes. Xenoskenea pellucida (Monterosato, 1874)-
Holotype: height 0.8 mm, width 1.04 mm. Largest Mediterranean.
mm
spécimen: 1.15 width.
Soft parts unknown. ACKNOVVLEDGEMENTS
Remarks. The gênerai aspect, protoconch, columella The authors thank Jesûs Méndez from the CACT1 of
and inner lip ofthis species are very similar to those Vigo University for the SEM photographs and the two
of Tomura bicaudata. from which it is différent by its référées fortheir useful comments.
smaller size and microsculpture formed by spiral
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Figures 14-23. Tomura umbiliobsessa spec. nov., Dakar, Sénégal.
14. holotype, 1.04 mm (MNCN 15.05/47.524): 15. paratype, 1.06 mm (CJH); 16. paratype, 1.15 mm (AMNH);
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158
E. ROLÂN& F. RUBIO NOVAPEX 9 (4): 155-160, 10 novembre 2008
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