The high popularity of a commercial sea cucumber species on Pangkor Island (i.e. Stichopus horrens) has resulted in a lack of studies on Holothuria (Mertensiothuria) leucospilota from Pangkor Island, Perak, Malaysia. S. horrens is the main ingredient of gamat-based traditional medicine on the resort island, while H. leucospilota is the most dominant species. For that reason, this study aimed to isolate ossicles from a specimen of morphospecies H. leucospilota collected from Teluk Nipah Beach, Pangkor Island; and to determine the shapes of the ossicles for species verification. A number of six ossicle shapes were observed. Beside buttons and tables as the common ossicle shapes; I-shaped rod, long I-shaped rod, branched rod, and spider-shaped rod were also documented. Nonetheless, the spider-shaped rod is an unusual ossicle shape in H. leucospilota as there was no previous record on it, thus it could be considered as a new finding. In summary, the results of this research indicate the uniqueness of the specimen of morphospecies H. leucospilota as a result of the presence of the spider-shaped rod. More studies with more samples, more morphological approaches as well as more molecular techniques need to be incorporated in future for a better insight.
This study aimed to resolve the taxonomic status of a morphologically undetermined sea cucumber species of order Apodida
from Malaysia (GenBank accession no.: FJ223867) using partial 16S mitochondrial rRNA gene sequences and subsequently
to determine the validity of morphological taxonomy of Holothuria species into its current subgenera. The undetermined
species clustered with all taxa of Holothuria in previous study. Phylogenetic analyses using maximum parsimony and
Bayesian methods suggest that the undetermined species was genetically closer to Holothuria (Lessonothuria) pardalis and
Holothuria (Acanthotrapeza) coluber; and its position in both phylogenetic trees further suggests its status as a Holothuria
taxon. Subgenera of Holothuria, Merthensiothuria and Metriatyla are monophyletic with strong bootstrap supports and
posterior probabilities of clades, thus strengthening their morphological taxonomies. Nonetheless, the non-monophyly of
subgenera of Halodeima, Microthele and Platyperona suggests a requirement for their taxonomic revisions using integrative
taxonomy. The status of Holothuria (Halodeima) edulis subgroups in the maximum parsimony and Bayesian trees is
indistinct and further taxonomic revisions are necessary. In terms of sister relationship, both phylogenetic trees suggest
that subgenus Holothuria is a sister taxon of subgenus Roweothuria while the other sister relationships were unclear due
to the undetermined species, paraphyly and polyphyly of a number of subgenera. Further studies with more specimens of
genus Holothuria from broader geographical locations and various mtDNA genes along with morphological approaches
may facilitate to provide better insights into the molecular phylogeny of subgenera of Holothuria.