Tridacna noae (Röding, 1798) – a valid giant clam species separated from T. maxima (Röding, 1798) by morphological and genetic data
Su, Y.; Hung, J.-H.; Kubo, H.; Liu, L.-L. (2014). Tridacna noae (Röding, 1798) – a valid giant clam species separated from T. maxima (Röding, 1798) by morphological and genetic data. Raffles Bull. Zool. 62: 124-135
In: The Raffles Bulletin of Zoology. National University of Singapore: Singapore. ISSN 0217-2445, more
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Tridacninae, CO1, 16S rRNA, 18S rRNA, 28S rRNA, lectotype, Taiwan |
| Authors | | Top |
- Su, Y.
- Hung, J.-H.
- Kubo, H.
- Liu, L.-L.
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| Abstract |
The taxonomic status of a giant clam species Tridacna noae (Röding, 1798) in relation to its congener T. maxima (Röding, 1798) was examined by a combination of molecular and morphological analyses. Until recently, T. noae was considered conspecific with T. maxima. However, in this study, among the four genes (COI, 16S rRNA, 18S rRNA, 28S rRNA) examined, two (i.e., 16S rRNA and COI) genes grouped T. maxima into two distinct clades, suggesting that a cryptic species was involved. The genetic distance of the 16S rRNA gene between T. maxima and cryptic species was 0.042–0.048. In contrast, the differences within the clades comprising T. maxima and the cryptic species were 0–0.003 and 0–0.005, respectively. A careful comparison of morphological traits revealed differences between T. maxima and the cryptic species, and the shells of the latter species were consistent with the figures referred to by Röding for the species he named ‘noae’. Tridacna noae differs from T. maxima in the appearance and arrangement of hyaline organs on the mantle in living specimens. In contrast, shell characters such as numbers of radial ribs and prominence of rib scales, were relatively unreliable. Occasionally, prominent rib scales only grew in one valve of an individual, e.g., in one T. maxima specimen from Hongchia. Based on previous and the present studies, here, a formal taxonomic description of Tridacna noae (Röding, 1798) with the designation of a neotype is provided. |
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