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Senegal
Cone Shells
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Author : Le
Béon Roger
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A. The Environment
B.
The Landscapes
C. The Cone shells
D. ICONOGRAPHY & DISCUSSION
E. Comments
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This
article shows cones I have founded during a two years stay in Senegal
(1990-1992). It is a tentative to illustrate as accurately as possible
these species and to show the associate biota’s. For identification
it use the help of the " Les cônes du Sénégal "
publication by Marcel PIN and K.D. LEUNG TACK, publicised as a supplement
of La Conchiglia n° 277, in 1995.
This document
is the latest about this subject and even if the identification process
of identification used is not widely accepted, mainly by the scientific
old, it is still the most interesting publication concerning Senegal’s
cones.. The other popular existing publication about cones shells,
the " Cone shells " of Walls, is quite erroneous concerning
the Senegal’s cones, as Marcel PIN says. |
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| A.
The Environment |
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Atlantic ocean waters of
Senegal not allows an easy seashells collect by free diving as I
have done as well as beach comber fishing during low tide. The sea
, warm during summer is quite cold during winter. The visibility
is usually poor on the sea side, and very often, the sea state is
very hard with big waves due to the strong south west Alize wind,
during a long period of the year. Only the rocky area of the Cap
Vert peninsula allows such kind of collect during some quiet periods.
These areas are mainly situated at the north and west of Dakar city.
They are :
The
Yoff area, north of the peninsula with
numerous rocks that's appears at low tide.
The
N’Gor area, where close to rocks piles,
is a little sandy beach protected by the N’Gor island.
The
Almadies cape with rocks piles and two
little beaches .
The Ouakam area with
high cliffs at the base of the higher Senegal’s hill "
less Mamelles ", where some wide natural pools remains
at low tide.
The
Fann area between Ouakam and Soumbedioun
villages severely polluted an hardly beat by the waves.
All long the
corniche where are numerous little sandy
bays with rocks piles and natural pools . This area is also
quite polluted despite some hotels have their private beach
here.
Goree
island situated close off the Dakar port.
Here is a little beach surrounded by rocky areas and some high
cliff. It is probably the best spot for shelling but the pollution
is coming and some times the visibility is very poor.
The
Bel Air cape is edged by two beaches ,
the public " voile d’or " is a popular beach but totally
sterilised, and the private military beach with a long pier
and some rocky places. In all this area I never find any shell
except beach ones.
Southerly starts a
large area which lays from the Hann bay
to the Sine Saloum river mouth
and then the very far Casamance
province. On this " petite
côte " some little villages like Popomguine, N’Gaparu,
M’Bour and Joal Fadiouth allows to reach the sea side. Totally
polluted between Hann and the cap des Biches this area
only allows shelling at low tide and exceptionally by
snorkelling with a very low visibility reduced to less than
20 centimetres Southerly the area is very rich (marginellas,
helmets, volutes, murex, cones and even cypreae…), but the only
means to catch them is by using trawlers or diving off shore
on the rocky banks. Fishermen find very often interesting species
that you can buy.
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Goree island
one of the best diving spot
of Senegal.
Just here bellow, is the Tacoma wreck ( between 15 and 20 meters)
where is a very popular diving place used by the Dakar diving club.
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| B. The Landscapes |
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Goree island.
The old prison, now a museum. Here behind this place is a
submarine rock masswhere you can find if you are lucky some
beautiful sanguinolenta endemic or the cone unifasciatus
that is described lower.
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In the
far the Madeleines islands you
can see from the Fann ClaudeL district. The island is a zoological
reserve and the access is normally restricted. In the foreground
you can find some C. unifasciatus but in very
bad condition because the sea is often rough here.
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Typical
landscape of the petite côte
with black rocks appearing at low tide and protecting the
beach of the strong waves. Here in the N’Gaparou surroundings,
you can find at some periods of the year, numerous C.
cacao around the rocks. Free diving is difficult close
to the sea side because the visibility is very poor. You might
have the luck to find some beautiful Cyp. stercoraria
very often greenish or sometimes very black
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Typical
landscape of the petite côte
with black rocks appearing at low tide and protecting the
beach of the strong waves. Here in the N’Gaparou surroundings,
you can find at some periods of the year, numerous C.
cacao around the rocks. Free diving is difficult close
to the sea side because the visibility is very poor. You might
have the luck to find some beautiful Cyp. stercoraria
very often greenish or sometimes very black
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| C. The Cone
shells |
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In his study M. Pin described
eighteen species of Senegal’s cones. I only found thirteen of them.
That are absent of my inventory are :
C. brugieresi
(Kiener, 1945)
C. belairensis
(Pin-Leung Tack, 1989)
C. mediterraneus
(Hwass in Bruguière, 1792)
That do
not, naturally, means that they do not exist. My investigations
were probably outside their normal biotops. I’ve never investigated
the Yoff area that is the normal breading zone of C. bruguieresis
and C. mediterraneus as M. Pin says. On the other hand the Bel Air
area becomes a real malacological desert. The only cone I found
there was a big C. pulcher. The C.belairensis is disappeared
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The species I discovered
are :
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Species
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Author
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max.
Size (mm)
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Areas
& means of collect
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Sympatry
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hybridus
(lamarkii f. hybridus ?)
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Kiener,
1845
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From
Almadies to Ouakam
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tabidus
equinophilus
mercator
ermineus
pulcher
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| guinaicus |
Hwass
in Bruguière, 1792
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cacao
pulcher
ambiguus
ermineus
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| equinophilus |
Petuch,1975
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Almadies'
point
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Id.
hybridus
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| mercator |
Linne,
1758
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Almadies
to Ouakam
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Id.
hybridus
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| cacao |
Ferrario,
1983
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Petite
côte
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cacao
pulcher
ambiguus
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| cloveri |
Walls,
1978
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Région
Ouakam
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ermineus
hybridus
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unifasciatus
(nota)
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Kiener,
1845
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South
Ouakam
to Gorée
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hybridus
equinophilus
ermineus
pulcher
genuanus
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| genuanus |
Linne,
1758
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Gorée
By fisherman (>20m)
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Id
unifasciatus
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| ambiguus |
Reeve,
1844
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By
fisherman
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Id
guineicus
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tabidus
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Reeve,
1844
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Almadies
to Gorée
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hybridus
equinophilus
ermineus
pulcher
genuanus |
| ermineus |
Born,
1778
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N’gor
Ouakam. Gorée
By fishermen Petite côte
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hybridus
equinophilus
ermineus
pulcher
genuanus
cacao
ambiguus
cloveri
mercator
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| pinaui |
Pin,1989
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By
diver Gorée area |
Id.
unifasciatus |
| pulcher |
Lightfoot,
1786
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Everywhere
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All
species |
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| D. ICONOGRAPHY
& DISCUSSION |
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Conus hybridus (lamarkii
hybridus ?)
This cone is quite common in the north and west part
of the Cap Vert peninsula where it is less numerous than c.tabidus
and c. mercator. At low depth you can find it by free
diving . I discovered a special one near 12 meters deep at
the foot of the Ouakam cliffs. It is special by its elongate
form and its special drawing (but is it an hybridus ?)
. I have found some species bigger than 50 mm, maximum length
as Pin says.
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Typical
form of C. hybridus L : 51.5mm I
: 25.8mm
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L : 44.7mm
I : 21.2mm
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Almadies
(-1.5 metres)
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Ouakam
(-12 metres).
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Three beautiful specimen
of c. hybridus. >From left to right :
L : 51.5 . l :
25.8
L : 50.4 . l : 24.1
L : 51.4 . l : 25.7
Drawing are very
variable. It may be all blue grey
with always present
two clear bands at the lower third and at the shoulders level
on the back.
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Conus guinaicus
I only find two beached species
on the " petite côte ". That is true, I never
investigate the Popomguine area which is its birthing area as
M.Pin says. I nevertheless received few specimens from local
fishermen. It is quite easy to make the difference with C.
hybridus because it is more thicker with a lower spire and
a more regular drawing, the two white bands are absent or quite
obsolete. |
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Beautiful
specimen L: 53mm , l : 29mm
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L : 46mm
I : 27mm
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Conus mercator
This
kind small shell is present all long the north and west coast
of the Cap vert peninsula. Very easy to find it lives in very
little deep water. I never find it south of the N’Gor area
while Pin says it was present nee Dakar city . It may be that
is the result of the invading pollution ? It is easily
recognisable despite a very varying drawing.
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Typical
form. L : 39.2 mm , l :22.2 mm.
Sector de N’Gor (-0.5 metres).
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Two
beautiful species . d= 39 and 38 mm
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Different
drawings. The juveniles have often very special drawings that
become more classic when they become older.
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Conus cacao
This cone
which have been sometimes confused with C. mercator
in the past is obviously very different with a general light
brown pattern colour, more heavy, and presence of two clear
bands at the first third and on the shoulders levels, even
if the netting drawing and its general shape looks like this
one. It is usually found on the petite côte area near
N’Gaparou where the C mercator is absent. It
is numerous at some period of the year (breeding time ?)
half buried in the sand, close to the rocks.
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Large
specimen L : 45.1 mm , l : 258
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Series
with different patterns, but not as various as on c. mercator
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Conus cloveri
I
have find this species at only one place, at the foot of the
Ouakam cliff in a large natural pool at low tide. In this
very restricted area there were numerous pieces to gather
with some big C. ermineus in very bad state. This little
cone is quite easily recognisable and cannot be confuse with
any other cone. It can be considered as quite rare. Very nice
species in GEM condition are very rare.
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Typical
C. cloveri L : 30.5 mm, l : 16.4 mm.
Ouakam (-0.5
metres).
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Serial.
The drawing is quite constant but may obsolete on some specimens
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Conus unifasciatus
I have
some trouble identifying this species. Those I collected are
quite typical of the description by M.Pin. However the places
where I found them are quite different . Pin says they are
from the northern area of the peninsula, but mine comes from
and area spread from the Ouakam village and Goree island where
they do not inhabit with the other species that Pin says.
On an other hand their maximum length exceeds largely the
40 mm that Pin quotes.( 47 and 48 for the biggest).
I have
found a colony quite homogeneous both by its black brown colour
an its light weight aspect in regard to the other, in a very
narrow area in Goree island.
In fact
it seems to me, that apart its colour and for some specimens
its more thick appearance, this species looks like closely
to C. hybridus : same shape and density, same
length range, and presence of two white bands… ?
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C.unifasciatus
Fann area,( -0.5 metres).
L : 47.1
mm , l : 25 mm . White bands quite obsolete
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C .
unifasciatus from Gorée ,( -1.5 metres).
L : 48.3
mm , l : 27 mm. White bands more visible with some white
spots at the bands level.
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Serial
of C. unifasciatus from Goree. The white spots
are more numerous on the small specimens.
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Serial
of C. unifasciatus from the Ouakam/ Fann area.
Some specimens are grey and finely reticulated.
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Conus genuanus
Here is a very beautiful cone
with no identification problem. Its shape and drawing are very
constant. I only found one by diving at about 6 meters on a
sandy bottom in Goree island. This is quite normal because it
is usually found deeper. My other specimens come from fishermen
on the " petite côte ". |
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C.
genuanus, dredged in Hann bay . L :57.6 mm
. l : 35.5 mm .
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Serial.
Constant drawing.
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Conus ambiguus
I did not found this
species by myself. The specimen I have come from fishermen of
the " petite côte " area. There are two forms.
The small one have a smooth shell lightly coloured of pink brown.
The big form has a white background with some brown longitudinal
flames. On the two forms there are brown radial markings on
the shoulders. |
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Big form
specimen dredged
. L : 66 mm l : 35.5 mm.
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Small form
specimen dredged.
L : 36.2 mm,L : 20 mm
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Conus tabidus
This small cone is
quite common at small depth on all the Dakar peninsula except
its southern part. It lives often with C. mercator
and C. hybridus. Small sized it is covered with a quite
thick brownish periostractum ; There not any identification
problem apart with the small specimen of C. ambiguus.
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C.
tabidus
have rounded shoulders. The brown flames drawings are less
numerous on the spire area.
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c. tabidus. L :
31.8 mm,
l : 17.4 mm. Pointe
des Almadies (0.5 meters)
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c.
ambiguus might be confuse with C. tabidus
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Conus ermineus
This beautiful cone
is present on all the Cap Vert peninsula area and in the islands
so called where I had the opportunity to go and dive. Its
birthing area is probably wider and transatlantic. C. ermineus
() is also present in the Caribian area. It has a wide range
of length, colour and drawings ; Its biotop is also very
variable. You can found it in very few depth waters at low
tide as well as at depth closing 20 to 30 meters (off the
petite côte). However its shape is always the same and
it can be identified easily.
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Beautiful
specimen dredged in the petite côte area. L : 71.8
mm , l : 38.6 mm.
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Low depth
specimen from the N’Gor area
L : 62.3 mm , l : 37 mm .
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Specimens
without drawing, yellow pattern ; dredged off petite
côte. L : 52.7 mm , l : 29 mm.
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Two species
from Sal island ( Cabo Verde islands ). normal colour:
46 X 25.8 . red colour :
46 X 25.7
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Conus pinaui
Recently described by Marcel
Pin, it was named in honour of doctor Pinau, M. Pin’s friend,
french radiologist from Dakar and great shells collector. They
are both died recently. I had the opportunity to receive some
rare species of this fine cone from the Dakar diving club director.
Unfortunately only one remains in my collection, this explains
the poor iconography. Collected by scuba diving off Goree at
20 meters, it is exactly identical to the M.Pin description.
It do not looks like strictly to any other cone except, may
be, to a C. ambiguus (the small form), witch had lost
the drawings. |
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C. pinaui
from the Hann bay ( 15 to 20 metres).
L : 34.7 mm ; l : 20.4 mm. Typical form
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C. pinaui
and C. ambiguus side by side. Questioning ?
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Conus pulcher
Probably the world biggest
cone , C. pulcher is present every where in Senegal,
where it do not reach the huge size that you can find southerly
in the west Africa area. Juveniles specimens are more attractive
because of their more brighter colours and drawings. The specimens
I have collected by free diving between 0.5 and 12 meters in
the Cap Vert area, are broader and heavier than the dredged
specimens. |
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C. pulcher
typical from the Cap Vert peninsula, broad and heavy.
Collected at Bel Air, outside the pier. L : 133 mm .
l : 92 mm
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C. pulcher
dredged off the petite côte, Narrow and lighter.
L : 116 mm. L : 69 mm
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Conus equinophylus
This cone is illustrated here
but I had some difficulties due to its very short size to take
pictures. I have found 4 specimens of this tiny cone at the
pointe des Almadies area, in little depth water. The shells
are strictly identical to the description of M. Pin. |
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| E. COMMENTS |
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These comments are strictly personal
. They only give my feeling without any scientific evidence since
I do not have this competence. This will only show how difficult
the Senegal’s cones identification is. These shells need to be more
accurately studied
C.
mediterraneus : I had the opportunity to see
some specimens of this cone from the Alexandria area (Egypt),
which resemble closely to the C. hybridus illustrated
here. In an other hand the C. mediterraneus illustrated
in the Pin’s study do not give any distinctive clues to make
the difference with C. hybridus .
C.
unifasciatus : like I explained before, numerous
common characteristics exist with C.hybridus : general
shape, size, two white stripes…
C.
cacao : if you can easily distinguish this species
from C. mercator, you can also find numerous common clues
with C. hybridus : size, general shape,but a little
broader, and presence of two white bands…
Considering
that these cones are not living in the same places together,
and that they are spread from north to south of the peninsula
as follows : C. hybridus, C. unifasciatus, C. cacao,
we are allowed to ask the question if it is not the same
cone (why not C. mediterraneus ?), with some variations
due to the different biotops ?
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From
left to right : C. hybridus, C. unifasciatus, C.
hybridus, C. unifasciatus (Gorée), C. unifasciatus.
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From
left to right : 1 à 4 : C. unifasciatus,
5 : C. cacao
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I hope this article will
contribute a little to enhance the Senegal’s cones knowledge.
I am waiting for your comments. Send me a mail. contact : Rlebeon@wanadoo.fr
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