Refine
Year of publication
- 2017 (2) (remove)
Document Type
Language
- English (2) (remove)
Has Fulltext
- yes (2)
Is part of the Bibliography
- no (2) (remove)
Keywords
- 28S (1)
- Amphidromous prawn (1)
- Indo-West Pacific (1)
- Turbinidae (1)
- cox1 (1)
- deep-sea environments (1)
- molecular systematics (1)
- morphology (1)
- multi-locus phylogeny (1)
Macrobrachium australe is an amphidromous prawn living in the insular freshwater systems of the Indo-Pacific. Because it possesses few informative morphological characters, that often vary from one habitat to another, M. australe has produced much taxonomic confusion and has historically been described under eight synonyms. Here, 53 specimens collected throughout the Indo-Pacific under the name M. australe were phylogenetically and morphologically examined. Results revealed that what has been called M. australe belongs to at least two distinct species: M. australe, distributed from the Southwest Indian Ocean to the Central Pacific Ocean, and a cryptic species potentially restricted to the Northwest Pacific Ocean, here identified as M. ustulatum, which until now was considered as a junior synonym. Although they are not quite found in the same habitat (lentic-lotic), the presence of these distinct, and reciprocally monophyletic entities in the same rivers on the islands of Palau and Santo strongly favors the hypothesis of two reproductively isolated entities. Six morphological characters, including the proportions of the joints of the male second pereiopod, the shape of the epistome lobe and the armature of the fourth thoracic sternite, are evidenced as diagnostic. A neotype of M. australe is designated and deposited in the Muséum national d’Histoire naturelle in Paris.
In shelled molluscs, assigning valid species names to independent evolutionary lineages can be a difficult task. Most original descriptions are based on empty shells and the high levels of variation in shape, color and pattern in some groups can make the shell a poor proxy for species-level identification. The deep-sea gastropod turbinid genus Bolma is one such example, where species-level identification based on shell characters alone is challenging. Here, we show that in Bolma both traditional and molecular taxonomic treatments are associated with a number of pitfalls that can lead to biased inferences about species diversity. Challenges derive from the few phylogenetically informative characters of shells, insufficient information provided in original descriptions and sampling artefacts, which at the molecular level in spatially fragmented organisms can blur distinctions between genetically divergent populations and separate species. Based on a comprehensive dataset combining molecular, morphological and distributional data, this study identified several cases of shell-morphological plasticity and convergence. Results also suggest that what was thought to be a set of distinct, range-restricted species corresponds instead to a smaller number of more widespread species. Overall, using an appropriate sampling design, including type localities, allowed us to assign available names to evolutionarily significant units.