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A life history, morphologic and taxonomic study of Aplysia (Gastropoda: Opisthobranchia): A. brasiliana Rang 1828, A. cervina Dall and Simpson 1901 in the Lower Laguna Madre, Texas
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Thirty-five species of Aplysia are currently recognized. Four species live in the Lower Laguna Madre of Texas. Two of the species, A. brasiliana Rang 1828 and A. cervina Dall and Simpson 1901, had been observed mating when held in laboratory aquaria and some field-collected specimens exhibited color characteristics of both species. A series of 6 experiments were conducted to elucidate the taxonomic relationship of the two species. Crop content analysis and feeding preference studies indicated that the two species preferred different algal species. A. brasiliana preferred rhodophyte algae, while A. cervina preferred chlorophyte algae. Ecological niche surveys indicated that both species occur in higher numbers in areas of higher salinities and lower dissolved oxygen levels, but A. cervina only occurred in 3 of the 8 sampling sites, while A. brasiliana occurred in all 8. Autoradiographic studies and mating assays indicate that the two species mate, reproduce and produce reproductively viable offspring through the F3 generation. Molecular evidence from 16 s mtDNA indicates that the two species and a third species, A. fasciata Poiret 1789, are identical. 12s mtDNA indicates that there is one base pair difference between the three species. Temperature, salinity, microalgae and macroalgae were found not to promote different phenotypic expression when veligers were raised under different parameters. Morphological analysis indicated that radula formula, currently used to differentiate Aplysia species, is unreliable when applied to A. brasiliana and A. cervina. Radula formulae were found to be statistically insignificant in differentiating these two species. Penis morphology, parapodial fusion and the structure of the accessory genital mass were also found to be unreliable taxonomical indicators. All the data indicate that A. brasiliana, A. cervina and A. fasciata are all the same species. Of the three species, A. fasciata Poiret 1789 has precedence. A. brasiliana, A. cervina therefore become synonyms of A. fasciata.
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Includes bibliographical references (leaves 84-89).
Issued also on microfiche from Lange Micrographics.
Black, Sara Curran (2004). A life history, morphologic and taxonomic study of Aplysia (Gastropoda: Opisthobranchia): A. brasiliana Rang 1828, A. cervina Dall and Simpson 1901 in the Lower Laguna Madre, Texas. Master's thesis, Texas A&M University. Available electronically from
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