BIOLOGY, POPULATIONS AND DISTRIBUTION AREA OF THE EUROPEAN ENDEMIC SPECIES PTILOTHAMNION

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Thalassas, 2005, 21 (2): 21-30
                                                                        An International Journal of Marine Sciences

  BIOLOGY, POPULATIONS AND DISTRIBUTION AREA OF THE
      EUROPEAN ENDEMIC SPECIES PTILOTHAMNION
 SPHAERICUM (CERAMIALES, RHODOPHYTA) IN THE IBERIAN
                     PENINSULA.

P. DÍAZ TAPIA & I. BÁRBARA

Keywords: Ptilothamnion sphaericum, seaweeds, Rhodophyta, Iberian Peninsula, Galicia, Portugal, biogeography, vegetation,
conservation, morphology, reproduction.

 ABSTRACT                                                       Ptilothamnion sphaericum occurs from middle to
     A study of the distribution, biology                       lower intertidal in seaweeds communities
 populations of the European endemic species                    characteristic      in      sandy     rocky     like
 Ptilothamnion sphaericum along the Atlantic                    Rhodothamniella         floridula,   Ophidocladus
 coasts of the Iberian Peninsula, is shown. P.                  simpliciusculus, Plocamium cartilagineum,
 sphaericum is reported by 18 localities, from Lugo             Polysiphonia nigra, Hypnea musciformis or
 in the North of Galicia to Algarve in the South of             Ahnfeltia plicata populations, but in some
 Portugal; standing up Galicia as the European                  localities P. sphaericum covers the middle
 region containing the bigest number of citations.              intertidal rocks where it develops an extensive
 The morphology and reproduction of P.                          band. A field study of natural turfs and cultures of
 sphaericum is described, as well as its habitat.               tufts in laboratory show that P. sphaericum has a
 Iberian tufts of P. sphaericum -composed by rigid              hight ability to bear long dark periods. Individuals
 erect axes and prostrate axes with rizoids- match              growing at 6:18 and 9:15 light:dark photoperiods
 with the tufts described in the British Isles.                 exhibted symptoms of deterioration at 1-3 months
 Likewise polysporangia are similar to the ones                 and they not survived more than 3-4 months.
 described in the British Isles, however anomalous              Individuals longer surviving were grown at 1:23
 off-wite polysporangia located in the apex of axes             light:dark photoperiod; they lived in culture until
 and branches were observed in Galician material.               21 months since lower temperature, irradiance and
                                                                photoperiod were similar to its natural habitat. P.
                                                                sphaericum is a successful species that colonize
                                                                sandy rocky where sand buried the tufts of the
pidita@udc.es & barbara@udc.es
                                                                algae during several months. Survival and
Departamento de Biología Animal, Biología Vegetal y             colonization potential of new sustrata for P.
Ecología,                                                       sphaericum is established where environmental
Facultad de Ciencias, Universidad de A Coruña,
Campus de A Zapateira s/n, 15071 A Coruña, España.              conditions are too harsh.

                                                                                                                      21
P. Diaz Tapia & I. Barbara

                                                                    2005). The scarce information about the P. sphaericum
                                                                    distribution is due to it lives in rocky habitats mixed
                                                                    with sand, from lower intertidal to upper subtidal, and
                                                                    it is composed by small filamentosus thalli that are
                                                                    easilly confused with another species.
                                                                         In the Iberian Peninsula, P. sphaericum has only
                                                                    previously been reported in three localities nearby one
                                                                    another and all of them focus in the A Coruña's
                                                                    province (Bárbara et al., 2001, 2002, Díaz Tapia &
                                                                    Bárbara 2004). In the current reseachers that we are
                                                                    carrying about the flora and vegetation of sandy-rocky
                                                                    habitats of the Atlantic Iberian Peninsula we have
                                                                    found new populations of P. sphaericum, thus we
                                                                    increased the scarce information of this species in
                                                                    Spain. Taking into account that P. sphaericum is an
                                                                    endemic species poorly known, we have done a field
                                                                    study of its nature populations and cultures in
                                                                    laboratory to test its capacity of living in habitats
                                                                    where environmental conditions are too harsh (e.g.,
                                                                    moving sand scour and bury of substratum).

                                                                    MATERIAL AND METHODS

                                                                        Along the Atlantic Iberian Peninsula, more than 30
                                                                    localities were explored to find new populations and
                             Figure 1.                              complete the Iberian distribution area of Ptilothamnion
 Distribution area of Ptilothamnion sphaericum (A) Galway, (B)      sphaericum. Mainly, intertidal and upper subtidal
Clare, (C) Cork, (D) Cornwall, (E) Dorset, (F) Brest, (G) Galicia
 and Portugal. Localities in the Iberian Peninsula (1) Playa de
                                                                    rocky substrata near to the beaches were selected. The
 las Catedrales, (2) Peinzás, (3) Playa del Lago, (4) Playa de      cespitose vegetation was studied in samples from 100
 Santa Comba, (5) Playa de Barrañán, (6) Puerto de Sorrizo,         to 1600 cm2 where we estimated visually the percent
  (7) Playa de Leira, (8) Playa de Seaia, (9) Playa de Barizo,      cover for the main species (Tab. 1) and subsequently
(10) Ensenada de Barda, (11) Aguiño, (12) Ribeira, (13) Punta
 Area Brava, (14) Cangas, (15) Amorosa (Araujo, et al 2005.),       verified in the laboratory by stereo microscope and
     (16) Leça da Palmeira, (17) Buarcos, (18) Dona Ana.            microscope. The algal material was preserved in 4%
                                                                    formalin seawater at 4ºC in dark until its study in
                                                                    laboratory. The herbarium material is housed at the
                                                                    herbarium of the Universidad de Santiago de
INTRODUCTION
                                                                    Compostela (SANT).
                                                                        With the aim to test the variability of nature
    Ptilothamnion sphaericum (P.L. Crouan et H.M.
                                                                    populations, a seasonal field study was done from
Crouan ex J. Agardh) Maggs et Hommersand is an
                                                                    2002 to 2004 in three Galician localities (Barrañán,
European endemic species which is only known from
                                                                    Seaia and Barizo) where P. sphaericum was more
the warm-temperate NE Atlantic subregion 1, in the
                                                                    abundant. Moreover, to obtain data of thallus survival
terminology of Hoek & Breeman (1990). As it shown
                                                                    that could explain the ability of natural colonizacion
in the Figure 1, P. sphaericum was only reported for
                                                                    populations, some turfs of P. sphaericum were cultured
the northeast of France (J. Agardh, 1851), South of the
                                                                    in Petri's dish with seawater (Fig. 4H). The culture
British Isles (Maggs & Hommersand, 1993, Hardy &
                                                                    conditions were: temperature 10ºC, irradiance 15 µm
Guiry, 2003) and atlantic coasts of the Iberian
                                                                    m-2 s-1 (18-watt light aquarium Grolux tube) and
Peninsula (Bárbara et al., 2001, 2002, Díaz Tapia &
                                                                    photoperiod (light:dark, 9:15, 6:18 and 1:23).
Bárbara, 2004, Araújo et al., 2005, Peña & Bárbara

22
Biology, Populations and Distribution Area of the European Endemic Species Ptilothamniom Sphaericum (Ceramiales, Rhodophyta) in the Iberian Peninsula.

                                                                                over rocky-sandy sustrata by mean of prostrate axes
    Herbarium material:                                                         and rizoids (Fig. 3F-I). Dense mass of prostrate axes
    LUGO: Playa de las Catedrales, Ribadeo,                                     (Fig. 3G, H) irregularly branched, pinkish-red in
29TPJ490242, 4-XI-2003, SANT-Algae 15130.                                       colour, 35-90 µm wide, and composed of cells 1,5-4
Peinzás, Foz, 29TPJ396277, 19-II-2003, SANT-Algae                               diameters long. Erect axes and rhizoids grow in middle
15131.                                                                          position of prostrate cells (Fig. 3G-H) which is a
    A CORUÑA: Playa de Santa Comba, Ferrol,                                     distinctive character to Spermothamnion repens.
29TNJ580233, 22-I-2004, 26-IV-2005, SANT-Algae                                  Unicellular rhizoids (Fig. 3I), 30-40 µm wide, up to
15154, 15599. Playa de Barrañán, Arteixo,                                       750 µm long and ending up in unicellular discoid
29TNH358957, 11-IX-2002, 5-XI-2002, 5-XII-2002,                                 holdfast up to 100 µm in diameter. Ramification of the
5-I-2003, 19-III-2003, 18-X-2003, 24-XII-2003,                                  erect axes varies from a dense irregularly secund
SANT-Algae 15021, 15120, 15122-15127. Puerto de                                 arrangement of branches up to 4º order (Fig. 3A) to
Sorrizo, Arteixo, 29TNH352958, 18-X-2003, SANT-                                 axes unbranched. Axes bearing polysporangia are
Algae 14998. Playa de Leira, Carballo,                                          plentifully branched especially towards the tips (Fig.
29TNH297954, 3-III-2002, 4-XII-2002, SANT-Algae                                 3A, D). Erect axes dark red, sometimes brownish,
13884, 15128. Playa de Seaia, Malpica,
29TNH143975, 27-II-2002, 22-VIII-2002, 20-II-2003,                                A                                   B
11-XI-2003, 29-III-2005, SANT-Algae 13878-13880,
14632, 15121, 15132, 15133, 15550. Playa de Barizo,
Malpica, 29TNH102958, 10-XII-2000, 22-VI-2001, 3-
I-2003, 5-IV-2004, 8-IV-2005, SANT-Algae 12931,
13372, 15129, 15553, 15556. Ensenada de Barda,
Ponteceso, 29TNH059924, 21-I-2003, SANT-Algae
                                                                                  C                    D                                           E
13903. Aguiño, Ribeira, Ría de Arousa,
29TMH993077, 20-XII-2002, SANT-Algae 15153.
Punta Corbeiro, Ribeira, parte externa Ría de Arousa,
28-IV-2004, SANT-Algae 15148.
    PONTEVEDRA: Punta Area Brava, Cangas, Ría
de Aldán, 29TNG134825, 25-I-2004, SANT-Algae
15033. Rodeira, Cangas, Ría de Vigo, 29TNG205783,
17-III-2004, SANT-Algae 15152.
    MIHNO: Minho, Amorosa, 29TNG147098, 20-II-
2003.                                                                             F                                   G

    DOURO LITORAL: Leça de Palmeira,
29TNF240601, 26-X-2004, SANT-Algae 15551.
    BEIRA LITORAL: Buarcos (al noroeste),
29TNE075485, 15-XI-2004, SANT-Algae 15552.
    ALGARVE: Dona Ana, 29SNB296054, 8-V-2005,
SANT-Algae 15733.
                                                                                                              Figure 2.
                                                                                A B: Intertidal rocks of the playa de Seaia (20-II-2003 and 11-
    RESULTS AND DISCUSSION                                                      XI-2003, respectively), where Ptilothamnion sphaericum occurs
                                                                                in dense populations. C: Subtidal populations of P. sphaericum
    Description                                                                  in the playa de Barrañán (19-III-2003). D: playa de Seaia (22-
                                                                                  VIII-2002), mixte community of Plocamium cartilagineum and
    As Bárbara et al. (2001) show, individuals of                                   Hypoglossum hypoglossoides with P. sphaericum. E y F:
Ptilothamnion sphaericum from the Iberian Peninsula                               Intertidal turfs of P. sphaericum in the playa de Seaia (27-II-
match with the ones described by Maggs &                                         2002 over Lithophyllum incrustans and 11-XI-2003 over tubes
Hommersand (1993) for the British Isles. Thallus                                       of polychaetes, respectively). G: Mixe tuft of Hypnea
                                                                                   musciformis, Pterocladiella melanoidea and P. sphaericum
forms rigid tufts (up to 2,5 cm) composed by                                                 from the playa de Barrañán (11-IX-2002).
ecorticated erect filaments (Fig. 3A, D) which settle

                                                                                                                                                    23
P. Diaz Tapia & I. Barbara

                                                                Table. 1
        Galician vegetation samples containg Ptilothamnion sphaericum. Littoral level: (MI) middle intertidal, (LI) lower intertidal, (SU)
                                       subtidal. Wave exposure: (EX) exposed, (SE) semiexposed.

24
Biology, Populations and Distribution Area of the European Endemic Species Ptilothamniom Sphaericum (Ceramiales, Rhodophyta) in the Iberian Peninsula.

                                                                                                                                                   25
P. Diaz Tapia & I. Barbara

 A                    150                                     C
                                                                    1993). Polysporangia are sessile, 1-2 per cell, are
                                            550
                                                                    laterally produced near to the apex of the main axes
                                                                    and branches, in series or solitary (Fig. 3D, 4A, D).
                                                                    They are spherical (up to 100 µm in diameter) and
                                                                    contain 8-16 spores, 32-45 µm in diameter. Although
                                                                    tipical polysporangia were usually observed growing
                                                                    laterally to the axes, in Barizo (April 2004) and Seaia
                                                                    (March 2005) we observed several individuals with
                                                                    anomalous off-white polysporangia (30-100 µm in
                                    70 µm                           diameter) located in the apex of axes and branches
                                     B                              (Fig. 4B, C).
D               E                             G                          Ptilothamnion sphaericum is resemblance to some
                                                                    Spermothamnion species, especially with S. irregulare
                                                                    (J. Agardh) Ardissone (Maggs & Hommersand 1993),
                                                                    which is a common especies in sandy habitats of the
                                     180
                                                                    Atlantic coasts of Iberian Peninsula. It can be confused
                                 90 µm                                                      B   150         40 µm       C
 90             F

                                                            160

H

                                                                      A              1,5                                         350
10 months             9 months              1 month                                                                         D
                                                                     E              F                  1 mm
                           Figura 4.
     Ptilothamnion sphaericum. A: Branches with lateral
  polysporangia. B-C: Anomalous off-wite polysporangia. D:
Tipical lateral polysporangia. E: Swollen cells in the middle of
    apical axes. F-G: Apical rhizoids linking cells of closer
                                                                      1 cm
branches. H: Culture in Petri's dish from Seaia (left, right) and
  Barrañán (centre). A, D and E: Barizo (10-XII-2000); B-C:
       Seaia (29-III-2003); F-G: Barrañán (19-III-2003).

increasing from a barrel-shaped apical cell (Fig. 3B-                                                                   200
                                                                                                                    G
D), 70 µm wide and 0,7-1,5 diameters long, to
cylindrical cells 50-120 µm wide and 1-3 diameters                    H                               160

long in the middle of the erect axes. Erect axes contain
short and long cells together due to difference growing
cell. Cells contain numerous discoidal plastids (Fig.
3C) and cell wall 5-12 µm wide. As novelty for P.                                                                               40 µm
                                                                                                                I
sphaericum, swollen cells in the middle of apical cells
(Fig. 4E) and apical rhizoids (Fig. 4F, G) linking cells                                        Figura 3.
                                                                        Ptilothamnion sphaericum. A: Brancehd erect axes with
of closer branches were observed in nature populations              polysponangia. B: Apical cell and barrel-shaped cells. C: Erect
as well as in culture.                                               cells with numerous discoidal plastids. D: Branches bearing
     Sexual structures are unkown for P. sphaericumso                polysporangia. E: Tufts in lower axes of Ahnfeltia plicata. F:
                                                                     Habit. G-I: Prostrate axes bearing rhizoids in middle position
the classification in Ptilothamnion or Spermothamnion                  and several erect axes. A-D, H: Barizo (10-XII-2000); E:
genus is based in vegetative characters and the                     Barrañán (19-III-2003); F-G: Area Brava (25-IV-2004); I: Barizo
polysporangia development (Maggs & Hommersand,                                                (5-IV-2004).

26
Biology, Populations and Distribution Area of the European Endemic Species Ptilothamniom Sphaericum (Ceramiales, Rhodophyta) in the Iberian Peninsula.

with P. sphaericum, especially young individuals                                Rhodothamniella           floridula,       Ophidocladus
without long erect axes and branches. Both species can                          simpliciusculus, Hypoglossum hypoglossoides,
be distinguished in the positions of the rizhoids and the                       Plocamium cartilagineum, Gracilaria gracilis,
celler diameter, since in P. sphaericum, rihizoids grow                         Cladostephus spongiosus, Polysiphonia nigra and
in the middle of prostrate cells (Fig. 3G-I), whereas in                        Hypnea musciformis. Filaments of P. sphaericum form
S. repens they grow laterally and the diameter axes of                          a mixture of turfs with the ones of several species, like
P. sphaericum are bigger than the S. repens ones.                               Hypnea musciformis and Pterocladiella melanoidea
                                                                                (Fig. 2G). Often, P. sphaericum is unnoticed among
     Distribution                                                               filamentous species thereby samples of turfs have to be
     Ptilothamnion sphaericum was first reported to the                         study in the laboratory to a proper specific
Iberian Peninsula in the Playa de Barizo (Bárbara et                            identification. Especially, Ptilothamnion sphaericum is
al., 2001) and secondly in the Playa de Leira (Bárbara                          a common species in the subtidal vegetation of
et al., 2002). Subsequently, it was reported for the                            Ahnfeltia plicata, living over hard sustrata (Fig. 2C)
Playa de Barrañán (Díaz Tapia & Bárbara 2004) and                               with Jania longifurca, or epiphyte of A. plicata (Fig.
new record for Portugal by Araújo et al. (2005) in the                          3E) as it was described by Agardh (1851) in the
Minho's region. In the current studies that we are doing                        northwest France. In general, Spermothamnion repens
about the flora and vegetation of sandy-rocky, P.                               is an epiphytic species of A. plicata but it occurs in
sphaericum was found in 15 new localities, so it is                             middle and upper axes of A. plicata whereas P.
nowadays known in 18 localities along the Iberian                               sphaericum occurs in lower axes and over hard
Peninsula, from Lugo in the North of Galicia to                                 sustrata; thereby its thallus can be buried by sand for
Algarve in the South of Portugal (Fig. 1). Standing up                          several months.
Galicia as the European region containing the bigest                                The ecotonic habitats of sand and rock where P.
number of citations (14 localities) and overcoming the                          sphaericum occurs are very stressful for the seaweeds,
Brithis Isles, where it is reported only a few sites                            since they are usually scoured and buried by sand. In
(Maggs & Hommersand 1993, Hardy & Guiry 2003).                                  contrast with the rocky platforms, removing thallus
Taking into account that the number of Iberian                                  tissue, decreasing light and substratum, as well as
localities of P. sphaericum has increased in the last                           depth, duration of burial and degree of water motion
four years, it will feasible an increasing of new records                       are important disturbance agents modifying the
towards Cantabric sea and Mediterranean Spain. Even                             recruitment and settlement of spores and plant growing
in the Northern Africa since the lusitanic endemic                              in sandy-rocky substrata (Devinny & Volse 1978,
species Eryhroglossum lusitanicum Ardré was                                     D'Antonio 1986, Chapman & Fletcher 2002).
likewise reported for the Atlantic coasts of Morocco                            However, sandy-rocky substrata have a characteristic
(see Benhissoune et al., 2003).                                                 vegetation that usually cover the substratum owing to
                                                                                a selection of competitive species that can endure the
     Habitat                                                                    stressful condition of life, like the opportunists, stress-
     In the Atlantic Iberian Peninsula, Ptilothamnion                           tolerant and biotically-competent species commented
sphaericum is usually collected in sandy-rocky                                  by Littler et al. (1983). Filaments -retraining sand and
habitats (Fig. 2A-D) from middle and lower intertidal                           forming bushy cousions made of mixture of soft
to upper subtidal of exposed and semiexposed                                    substratum and algae thallus- are the predominant
localities and, recently, it was found in subtidal maërl                        vegetation covering the sand-rocky plataforms of the
beds of Galicia (Peña & Bárbara 2005). These soft                               northwest Iberian Peninsula similarly that Hommeril
substrata of the Iberian habitats are similar to the ones                       & Rioult (1965), D´Antonio (1986), Stewart (1983)
mentioned by Maggs & Hommersand (1993) for the                                  and Airoldi et al. (1995) observed in other countries.
British Isles and not present distinguished diferences in                       Like Airoldi (1998) comment the monopolization of
latitudinal variations.                                                         space may be remarkably persistent and it occurs
     Generally, Ptilothamnion sphaericum occurs from                            because the environmental conditions are too harsh,
middle to lower intertidal as a discrete species in                             allowing persistence of only those species that are
seaweeds communities characteristic in sandy rocky                              resistant o resilient to disruption or tolerant to stress.
(Table 1, Fig. 2D, G) like populations of                                       Distinguishing feature of P. sphaericum, as

                                                                                                                                                    27
P. Diaz Tapia & I. Barbara

                                                             Table 2
Field seasonal study (2002-2004) of Ptilothamnion sphaericum in four populations from three Galician localities: Playa de Seaia, Playa
                        de Barrañán and Playa de Barizo. Presence conditions: bur=buried, no=not observed.

                                  2000   2001               2002                                             2003                                 2004   2005
                                  Dec    Jun    Feb   Aug   Sep    Nov   Dec   Jan   Feb   Mar   Abr   May   Jun    Aug   Sep   Oct   Nov   Dec   Apr    abr
    Playa de      Presence and
      Seaia         size (cm)                    2     2                             2,5               bur          bur         bur    2          bur    2,5
    (middle       Polysporangia
   intertid al)        (%)                      20    no                             no                 -            -           -     5           -      5
    Playa de      Presence and
    Barrañán        size (cm)                               1,1    no    no    1,5         0,8                1                 1           0,7
  (subtidal, -1   Polysporangia
     metre)            (%)                                   5      -     -    80           5                 no                no          no
    Playa de      Presence and
    Barrañán        size (cm)                               0,4    1,5    2    bur         0,5   0,4                0,4                     0,7
     (lower       Polysporangia
   intertidal)         (%)                                   no    20    no                no    no                 no                      no
    Playa de      Presence and
     Barizo         size (cm)     0,5    0,5                 no                0,5                     no                 no                      1,2     1
     (lower       Polysporangia
   intertidal)         (%)        10     No                  -                 no                       -                  -                       5      -

development of a wide system of prostrate axes with                                   latidudes is lower than the one of the NW-Spain, from
numerous rhizoids and erect axes that surface through                                 11ºC to 18ºC.
the sand, explain that it be a competitive species in                                      Incomplete or asexual life histories, usually allied
stressed sandy-rocky habitats. Thereby, Ptilothamnion                                 to remarkable powers of regeneration are common in
sphaericum forms monospecific populations (Table 1,                                   cespitose algae living in sandy and rocky habitats
Fig. 2E, F) in some Galician localities. In the Playa de                              (Norton et. al 1982) and is in agreement with the
Seaia (Fig. 2A, B) P. sphaericum covers the middle                                    growth strategy of P. sphaericum. Sexual phases are
intertidal rocks where it develops an extensive band                                  unknown in P. sphaericum (Maggs & Hommersand
over Lithophyllum incrustans (Fig. 2A, E) and tubes of                                1993) however is necessary to stand out that in the
polychaetes (Fig. 2F), with few accompanying species                                  Playa de Barrañán (November 2002) we found some
like Rhodothamniella floridula, Pterocladiella                                        apical filaments bearing unfertilized procarps which
melanoidea, etc. In the Playa de Barrañán dense turfs                                 were anomalous and miscarried in appearance.
of P. sphaericum (Fig 2C) has only been observed in
the lower intertidal.                                                                     Seasonality of the populations
                                                                                          In the Playa de Seaia (Fig. 2A, B) Ptilothamnion
    Reproduction and phenology                                                        sphaericum covers the middle intertidal rocks where it
    According to Maggs & Hommersand (1993),                                           develops an extensive band over Lithophyllum
individuals obtained by cultures of spores have not                                   incrustans (Fig. 2A, E) and tubes of polychaetes (Fig.
developed sexual structures and populations,                                          2F), with few species like Rhodothamniella floridula
apparently, reproduced by extensive propagation of                                    and Pterocladiella melanoidea. P. sphaericum forms a
prostrate axes followed by fragmentation of thalli.                                   dense and stable population that can be buried by 1
Polysporangia are the unique known reproductive                                       meter of sand during several months (Fig. 2B, D).
structures. In the Atlantic coast of the Iberian                                      Only few days per years the sand was withdrawed
Peninsula, we found polysporangia from January to                                     from the rocks of Seaia beach, in parallel to
April, September, November and December, and none                                     southwestern swell and wind. Hence that populations
observations of them in the hot season. In the                                        of Seaia was only observed unburied in February, April
populations of Barrañán, Seaia and Barizo we found                                    and November, however P. sphaericum seen to be
polysporangia in few months (Table 2) being abundant                                  present all months of the period and it survived long
in January, February and November. In the Brithis                                     buried time, since always the sustratum was unburied
Isles, Maggs & Hommersand (1993) observed                                             of sand we collected alive individuals of P.
polysporangia in March and Augoust, which could be                                    sphaericum.
close to Galicia since the temperature in August in high                                  Since the first collection in Seaia (February 2002)

28
Biology, Populations and Distribution Area of the European Endemic Species Ptilothamniom Sphaericum (Ceramiales, Rhodophyta) in the Iberian Peninsula.

                                                                 Table. 3
 Culture in laboratory (2003-2004) of Ptilothamnion sphaericum from two Galician localities: Playa de Seaia and Playa de Barrañán.
                                          Individual conditions: liv=live, dyi=dying, dea=dead.

                              Photoperiod                            2003                                       2004                 2005
                               light:dark      Feb    Mar     Apr    May     Jun    Sep   Nov     Dec    Feb     Jun     Jul   Oct    Jan    Apr
                                  9:15          liv    liv    liv     dyi    dea
       Playa de Seaia             6:18          liv    liv    liv     dea
     (middle intertidal)
                                  1:23          liv    liv    liv     liv    liv    liv    liv    liv     liv     liv    liv   dyi    dea
                                  1:23                                                     liv    liv     liv     liv    liv   liv    dyi     dyi
                                  9:15           -     liv    dyi     dea    dea
     Playa de Barrañán
     (lower intertidal)           6:18           -     liv    dyi     dyi    dyi    dea
                                  1:23           -     liv    liv     liv    liv    liv    liv    liv     liv    dyi    dyi    dyi    dea

neither decline of the area occupied by P. sphaericum                           sphaericum was observed in the mayority of the
no changes in location of the original population was                           months. The thalli were 0,7-1,5 cm long and no
detected. In adition, erec axes are longer (2,5 cm long)                        seasonal variations were detected. In lower intertidal
than the others localities (Table 2). In contrast, the                          and upper subtidal was present all period with little
apical cells from Seaia are more pale in colour (lower                          variations in abundance; however in subtidal
pigmentation) than the ones collected in other                                  populations of Ahnfeltia plicata, from December 2002
localities, conceivably, due to recent propagation of                           to March 2003, P. sphaericum was unmonitored owing
erect axes is produced when the sustratum is unburied,                          to A. plicata was saturated by fuel oil from the
which is only during one or two weeks. Erects axes                              oiltanker "Prestige" (Bárbara 2002). In three months
remain dormant during long buried periods, so growth                            the thalli were almost cleaned and the abundance of A.
and reproduction run slow in the Ptilothamnion                                  plicata and its epiphytes were similar to the original
sphaericum populations. It can be possible that the                             one (Díaz Tapia & Bárbara, 2004).
propagation carried out when thallus of P. sphaericum                                Barrañán's tuft growing in culture at 6:18 and 9:15
are uncovered by sand, so if P. spaericum is collected                          light:dark photoperiods exhibted symptoms of
one or two days after the sand has been withdraw from                           deterioration at 1 month and no survived more than 3-
the substratum the apical cells are pale in colour.                             4 months (Table 3). Similarly to the Playa de Seaia,
Polysporangia are scarce and inmature after two or                              individuals longer surviving from Barrañán were
three days unburied and its development agreement to                            grown at 1:23 light:dark photoperiod; they lived in
the intesive asexual and vegetative propagation                                 culture no more than 20 months.
mentioned by Norton et al (1982) for cespitose algae                                 In the Playa de Barizo, Ptilothamnion sphaericum
living in sandy and rocky habitats.                                             is known since December 2000 when the species was
    To test the ability survival of Ptilothamnion                               new record from Spain (Bárbara et al. 2001). From
sphaericum in stressed sandy habitats, tufts from the                           June 2001 to April 2005 we sampled (January,
Playa de Seaia were cultured in laboratory (Table 3,                            February, April, May, June and September) the sandy
Fig. 4H). Individuals growing at 6:18 and 9:15                                  rocky habitats of Barizo beach (Ahnfeltia plicata and
light:dark photoperiods exhibted symptoms of                                    Rhodothamniella floridula vegetation), but P.
deterioration at 2-3 month and they not survived more                           sphaericum was only found in June 2001, January
than 4 months. Individuals longer surviving were                                2003 and April 2004. In general, collection shortages
grown at 1:23 light:dark photoperiod. They lived in                             of P. sphaericum is due to burying by sand. Individuals
culture for 21 months (Table 3) since lower                                     of P. sphaericum were small (1,2 cm long) and usually
temperature, irradiance and photoperiod were similar                            vegetative, except in December 2000 and April 2004.
to its habitat and explain why P. sphaericum is a
successful species that colonize sandy rocky where
sand buried the tufts of the algae during several                               ACKNOWLEDGEMENTS
months.                                                                            We thank to Rita Araújo (University of Oporto,
    In the Playa de Barrañán Ptilothamnion                                      Portugal) and Estíbaliz Berecibar (University of

                                                                                                                                                    29
P. Diaz Tapia & I. Barbara

Algarve, Portugal) for their support with the field-           275.
work. Likewise we thank two anonymous referees for         Díaz Tapia, P. & Bárbara, I. 2004. Vegetación algal de
their suggestions and corrections to the manuscript.           ambientes rocoso-arenosos de Galicia y su relación
                                                               con el vertido del Prestige. Bol. Inf. Soc. Esp.
                                                               Ficol., 31: 28-33.
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                                                           (Received: July, 16, 2004. Accepted: April, 8, 2005)

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