International Journal of Marine Science 2016, Vol.6, No.33, 1-7
6
4 Discussion
A morphological analysis has been done for
Kappaphycus
and
Eucheuma
samples based on plant size, color,
branch diameter, branching patterns and thalli texture (Tan et al., 2013). Branch diameter, branching patterns and
thalli texture are the main differentiating criteria for
K. alvarezii
,
K. striatus
,
K. malesianus
and
E. denticulatum
.
Specimen AS 12 has the largest branch diameters, followed by
K. alvarezii,
K
.
striatus
,
K. malesianus
and
E.
denticulatum
. Specimen AS 12 has low branching frequency as compared to
K. striatus
(highest branching
frequency),
K. malesianus
and
K. alvarezii
. The main morphological difference between
K. alvarezii
,
K. striatus
,
K. malesianus
and specimen AS 12 is that
K. alvarezii
is characterized by its long and cylindrical thalli and sparse
branches with sharp pointed,
K. striatus
is characterized by stubby and thick cylindrical branches with blunt and
forked tips, which resemble a cauliflower shape (Hurtado et al., 2008),
K. malesianus
is characterized by
smoother and slender to flexuous terminal branches without blunt protuberances scattered throughout its thalli
(Tan et al., 2014), while specimen AS 12 is characterized by its thick and trapezoid-like thalli covered with dense
short protrusions. Morphologically the specimen AS 12 can be readily distinguished from
K. alvarezii
,
K. striatus
,
K. malesianus
and
E. denticulatum
by having entire margins and the short protrusions as compared to other
Kappaphycus
species and
E. denticulatum
. Unlike the fleshy and cartilaginous nature of
Kappaphycus
species, the
thallus of the specimen AS 12 is harder and inflexible
.
The size of plant is obviously smaller than
K. alvarezii
,
K.
striatus
,
K. malesianus
and
E. denticulatum
.
The mitochondrial-encoded
cox
2-3 spacer, nuclear-encoded ribosomal internal transcribed spacer (ITS) and
plastid-encoded RuBisCo spacer were selected because they are adequate molecular markers for the determination
of species boundaries according to number of studies carried out on different orders of red algae including
Kappaphycus
and
Eucheuma
(Zuccarello et al., 2006; Conklin et al., 2009; Zhao and He, 2011; Tan et al., 2013).
Our molecular phylogenetic analyses revealed its uniqueness, with a sufficient amount of gene sequence
divergence from its putative relatives. The high level of congruence and bootstrap values between trees of
cox
2-3
spacer, ITS region and RuBisCo spacer datasets showed the distinctness of the specimen AS 12. The specimen AS
12 was placed in
Kappaphycus
clade, as a sister taxon to
K. alvarezii
;
K. striatus
and
K. malesianus
. This
specimen is believed to have shared the same common ancestor with that of
Kappaphycus
species. In addition,
there is no affinity of the specimen AS 12 to the gene sequences available in GenBank and it might probably be a
new species or variety. The exact taxonomic status of this entity remained unresolved and its true identity will
require further clarification.
Author’s contributions
V. Y. Thien collected the samples and conducted the experiments. W. T. L. Yong and G. J. W. L. Chin supervised the samples
preparation, analysis and characterization. All authors read and approved the final manuscript.
Acknowledgements
The authors wish to thank the Biotechnology Research Institute of Universiti Malaysia Sabah for funding and providing facilities for
the research.
References
Conklin K.Y., Kurihara A., and Sherwood A.R., 2009, A molecular method for identification of the morphologically plastic invasive algal genera
Eucheuma
and
Kappaphycus
(Rhodophyta, Gigartinales) in Hawaii. Journal of Applied Phycology 21: 691-699.
Góes H.G., and Reis R.P., 2011, Temporal variation of the growth, carrageenan yield and quality of
Kappaphycus alvarezii
(Rhodophyta, Gigartinales)
cultivated at Sepetiba Bay, southeastern Brazilian coast. Journal of Applied Phycology 24: 173-180.
Hurtado A.Q., Critchley A.T., Trespoey A., and Bleicher-Lhonneur G., 2008, Growth and carrageenan quality of
Kappaphycus striatum
var.
sacol
grown at
different stoking densities, duration of culture and depth. Journal of Applied Phycology 20: 551-555.
Munoz J., Freile-Pelegrin Y., and Robledo D., 2004, Mariculture of
Kappaphycus alvarezii
(Rhodophyta, Solieriaceae) color strains in tropical waters of
Yucatan, Mexico. Aquaculture 239: 161-177.
