Dissertation/Thesis Abstract

Molecular Phylogenetics and Species Divergence in Selected Pinnotheridae (Crustacea: Brachyura: Decapoda)
by Palacios Theil, Emma, Ph.D., University of Louisiana at Lafayette, 2014, 245; 3687699
Abstract (Summary)

The family Pinnotheridae comprises about 300 species separated in two subfamilies, Pinnotherinae and Pinnothereliinae. They are symbiotic decapod crustaceans that live in association with other invertebrates, such as bivalves, gastropods, sea cucumbers, sand dollars, tunicates, polychaete worms, or ghost shrimps. Pinnotherids could represent an excellent model for studies of biogeography and evolutionary ecology, but their small size and cryptic nature, together with the high biodiversity in the group, have posed a challenged to carcinologists and taxonomists for decades.

Here the evolutionary history of the group was studied using molecular markers and comparisons to morphological observations. The resulting phylogenies indicated that the species Parapinnixa cortesi, Parapinnixa hendersoni, Pinnotherelia laevigata, Sakaina yokoyai, Tetrias fischerii, and Tetrias scabripes must be removed from the family Pinnotheridae. After removing the monotypic genus Pinnotherelia, type of the subfamily Pinnothereliinae, remaining species of the former subfamily were assigned to Pinnixinae, a new subfamily based upon revision and elevation of rank for the tribe Pinnixini Števčić, 2005. In addition, the subfamily P___ , was proposed to accommodate species that were excluded from the other two subfamilies.

At the generic level results confirmed that Clypeasterophilus, Dissodactylus, Fabia, Nepinnotheres, and Pinnixa are not monophyletic. Nineteen species were removed from the genus Pinnixa. Eleven of them are reassigned to existing genera: P. faba, P. franciscana, P. littoralis, P. schmitti, P. tomentosa, and P. tubicola are placed within the genus Scleroplax, whereas P. abbotti, P. arenicola, P. faxoni, P. floridana, and P. vanderhorsti are reassigned to Glassella. T___ n. gen. is erected to receive P. chaetopterana, and taxa in the P. brevipollex – P. rapax complex while J___ n. gen. was erected to receive members of the P. pearsei – P. sayana complex, P. affinis, and species in the P. californiensis – P. occidentalis complex.

At species level, the molecular data supported observations based on morphology and confirmed the existence of five new pinnotherid species, three in the genus Austinixa, one in Tumidotheres, and one in Pinnixa. Two of them, Austinixa r___ and Tumidotheres c___ , were described here.

Indexing (document details)
Advisor: Felder, Darryl L.
Commitee: Bauer, Raymond T., Cuesta, Jose A., France, Scott C., Neigel, Joseph E.
School: University of Louisiana at Lafayette
Department: Biology
School Location: United States -- Louisiana
Source: DAI-B 76/08(E), Dissertation Abstracts International
Subjects: Ecology, Systematic, Zoology
Keywords: Biogeography, Cryptic species, Evolutionary history, Marine symbiosis
Publication Number: 3687699
ISBN: 978-1-321-65582-7
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