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R, J.G.M. A S, A., . e
rst record in more than a century of Solemya
togata (Poli, ) (Bivalvia: Solemyidae) from the
Cantabrian Sea a nd notes on its presence in the I be-
rian At lantic – Basteria , (): -. Leiden. Pub-
lished 20 December 2024.
Key words: Bivalvia, Solemya togata, Asturias, Cantabrian
Sea, Iberian Peninsula.
Summary
Two juveniles of Solemya togata (Poli, ) have been found
in the marina of Gijón, Asturias. As only juveniles were
found it appears the species has recently settled there. It
is the rst record from the Cantabrian Sea in more than a
century and the rst record from Asturias. Possibly, this is
the northern limit of its distribution area.
Resumen
Dos juveniles de Solemya togata (Poli, ) han sido encon-
trado en la marina de Gijón, Asturias. Como solo se encon-
traron especímenes juveniles parece que la especie se ha
establecido recientemente. Es la primera cita del Cantábrico
en más de un siglo y la primera cita de Asturias. Posible-
mente ese es el límite septentrional de su área de distribu-
ción.
INTRODUCTION
Solemya togata (Poli, ) is a bivalve with an elongated
shell and very characteristic dark brown periostracum
with radial ribs that extend beyond the valves as irregular
fringes. e Solemyidae are chemosymbiotic (having sul-
phide oxidising chemoautotrophic bacteria living within
their gills) oen associated with seagrass beds (Taylor et al.,
; Rueda et al., ; Oliver et al., ).
Unexpectedly two juvenile specimens were found in the
marina of Gijón (°'N, °'W), Asturias, Spain (Fig. ).
e largest is a single valve of . mm length, the other a
fresh pair of . mm that may have been alive when sam-
pled (Figs -). Note that the smallest specimen does not yet
have the periostracum extending beyond the valves.
MATERIAL AND METHODS
Sampling in the marina was carried out with a small dredge
of approximately litre volume. e muddy bottom was
sampled multiple times during and from a jetty
in the Fomento Dock and in January twice from the
jetty closest to the entry of the marina in the Exterior Dock
reserved for visitors (Fig. ). Many tens of litres of sediment
have been sieved. Over the last year the muddy bottom has
largely been covered by the invasive sea weed Gracilaria
vermiculophylla Ohmi.
e development of Poniente beach, constructed with
sand dredged from oshore Luanco, has been monitored
since the ’s. Since about years a small eld of dwarf
eelgrass Zostera noltei Hornemann, has developed on
the muddy seabed in front of the easternmost part of the
beach. At exceptionally low tides the seagrass eld has been
inspected directly. More regularly fresh, empty shells of
molluscs that supposedly lived between the seagrass have
been collected from the beach immediately adjoining the
seagrass eld. As seagrass is a preferred habitat for Solemy-
idae, on the th of August the sea grass was visually
inspected whilst snorkelling, sand from patches between
the seagrass was collected and sieved, and a week later the
seagrass was again visually inspected during low tide and
more sand patches were sampled (in total > litres of sand
were sieved).
e rst record of Solemya togata (Poli, 1791) (Bivalvia: Solemyidae)
from the Cantabrian Sea in more than a century and notes
on its presence in the Iberian Atlantic
J.G.M. (H) R
Naturalis Biodiversity Center, P.O. Box , RA Leiden, e Netherlands; han.raven@naturalis.nl [corresponding author]
A A S
Inesto ,º J, Gijón, Asturias, Spain
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J.G.M. R A. A S – Solemya togata Iberia
January a similar volume was sieved delivering a
younger pair.
Aer the seagrass eld established at Poniente beach,
fresh pairs of other species of bivalves were regularly found
on the adjoining part of Poniente beach: Lucinella divari-
RESULTS
Initial sieving (on th January ) of an estimated
litres of mud from the Exterior Dock of the Gijón marina
delivered a single valve. During a second visit on the th
Fig. 1. Sample localities in the Gijón marina and the seagrass eld at Poniente beach, Gijón, Asturias (Google Earth).
Figs 2-3. Solemya togata from the Exterior dock at the Gijón marina (coll. R, ). 2. Juvenile pair, L . mm. 3. Juvenile valve, umbo
damaged, L . mm.
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J.G.M. R A. A S – Solemya togata Iberia
Rolán et al. (: -) recorded it from the outer parts
of the Vigo estuary, with living specimens in the lagoon of
the Cíes islands and valves from Patos and the Baiona Bay,
whereas Rolán & Otero-Schmitt (: ) also recorded it
from the Arousa estuary, all on the Atlantic coast of Gali-
cia. Hidalgo () gives more details on the record from
Santander, stating it was found in mud at the “playa del
Semáforo”, referring to the signal previously installed on
the Magdalena Peninsula, thus one of the beaches on the
eastern side of this peninsula (now divided by breakwaters).
No later records from the city A Coruña or from Santander
are known.
Interestingly, on th April Marc Lavaleye found
tens of fresh pairs on the beach Praia Troia Mar (.
N, . W) on an isthmus just south of Setúbal in Por-
tugal (Fig. ). It was beached with seagrass. Undoubtedly
shells and seagrass originated from the Sado estuary nature
reserve just east of Setúbal, renowned for its seagrass elds.
It is included in the checklist of macrofauna living at that
locality (Ferreira et al., ), documenting its high bio-
diversity. An overview of localities in the Iberian Atlantic
from which the species has been recorded is given in Fig. .
According to Poppe & Goto (: ) S. togata usually
has a length of to mm, exceptionally over mm. In
Galicia they reach mm (Rolán & Otero-Schmitt, :
). By all means our specimens are juveniles. e smallest
is < year old, the larger one < years. As no specimens have
been recorded before and no adults have been found, it is
likely the species has recently settled here.
cata (Linnaeus, ), Cerastoderma edule (Linnaeus, ),
Parvicardium exiguum (Gmelin, ), Bosemprella incar-
nata (Linnaeus, ), Spisula subtruncata (da Costa, ),
Polititapes aureus (Gmelin, ) and Ruditapes decussatus
(Linnaeus, ). ese are clearly animals that lived in the
mud between the seagrass. Part of the Polititapes aureus
were cracked, typically on the posterior side, due to pre-
dation by crabs. During the snorkelling and from the sed-
iment samples, amongst others, also living Loripes orbicu-
latus Poli, , Tritia reticulata (Linnaeus, ) and Tritia
varicosa (W. Turton, ) were observed. us far no Sole-
mya togata have been found there, but the area is clearly
still developing.
DISCUSSION
According to Huber (: -) the species is known
from the eastern Atlantic from Iceland to South Africa, and
the Mediterranean, but is rare everywhere (Poppe & Goto,
: ) and usually occurs in low numbers. However, no
records have been found for Norway or Iceland (e.g. Hisae-
ter, ; Warén, , ; Hansson, ; Delongueville et
al., ), (e.g. Oliver et al., ; Atlas), North Sea
(Kreps, ) or the Atlantic coast of France (e.g. &
, -). Cosel & Gofas (: ) state it ranges
from northern Spain (Ria de Vigo) to southern Angola and
throughout the Mediterranean. In the collections of Natu-
ralis the only European lots of S. togata are from the Canary
Islands and the Mediterranean. us the records by Hidalgo
(: ), from Santander along the coast of the Cantabrian
Sea in NW Spain could be the northernmost of its distribu-
tion area. H idalgo () also lists Coru ña (with which he pos-
sibly indicated the region Galicia) and Setúbal in Portugal.
Fig. 4. Solemya togata (arrow) on the Praia Troia Mar, south of
Setúbal in Portugal (Fig. ). Note the dried seagrass. Photo: Marc
Lavaleye.
Fig. 5. Localities in the Iberian Atlantic from which Solemya
togata has been recorded (base map Google Earth).
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J.G.M. R A. A S – Solemya togata Iberia
reviewed the paper and made several good recommenda-
tions that improved this paper.
REFERENCES
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In Galicia the species preferably lives in seagrass elds
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morpha intestinalis (Linnaeus, ) (Huber, : -;
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Despite our limited sampling, the Gijón marina was
found to harbour an impressive biodiversity with more
than species of molluscs, most of them living and
reproducing within the marina (in the mud or attached
to the jetties). Of some species only a few juveniles have
been found, which may represent the occasional arrival of
planktonic larvae. ese may die before becoming adult,
may grow up without reproducing or eventually may estab-
lish a local population. e specimens of S. togata lived in
the muddy substrate of the marina. As only a few m of
substrate were sampled it is likely that many more juve-
niles live there now and they could develop into a repro-
ducing population of this rare species. e marina has
been awarded a ‘’bandera azul’’ (blue ag) for many years,
amongst others because of its environmental management,
which clearly is paying o.
e seagrass eld on the eastern side of Poniente beach
would also provide an excellent habitat, which could be
reached directly by planktonic larvae or indirectly from
the marina through undirected swimming of larger spec-
imens. It is hoped it establishes a healthy population. Fur-
ther monitoring and sampling at both localities is recom-
mended. Currently the marina is well suited, although
further expansion of Gracilaria vermiculophylla could
choke part of the bottom fauna. e seagrass eld is rather
exposed as the plants are trampled on by bathers at low tide
during summer. It is hoped it will be allowed to develop
further – as it could host other rare species.
ACKNOWLEDGEMENTS
e Consejería De Medio Rural Y Cohesión Territorial of
the Government of the Principality of Asturias is thanked
for the collection permit which enabled our study. Marc
Lavaleye provided the interesting data and photo of S.
togata from Sebúbal. Frank Wesselingh (Naturalis) pro-
vided access to the stereomicroscope with which the photos
were made. Graham Oliver (National Museum of Wales)
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J.G.M. R A. A S – Solemya togata Iberia
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