Macroderoides texanus n. sp. (Digenea: Macroderoididae) from alligator gar, Atractosteus spatula in Texas
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Macroderoides texanus n. sp. is described based on 16 specimens collected from the intestine of the North American alligator gar, Atractosteus spatula. Of the five established species of Macroderoides, the new species is morphologically most similar to Macroderoides spiniferus and Macroderoides trilobatus. M. texanus n. sp. differs from M. spiniferus by having the ovary situated immediately posterior to the cirrus sac rather than at mid-way between the cirrus sac and anterior testis, the ventral sucker situated further posteriorly, and the vitelline fields extending somewhat posterior to posterior testis rather than to the middle of posterior testis. M. texanus n. sp. differs from M. trilobatus by having the ovary positioned immediately adjacent to, or overlapping the cirrus sac rather than at some distance posterior to it, and by having significantly larger eggs. Additionally, the new species has two distinctive rows of spines on the postero-ventral surface of the oral sucker that are lacking in M. spiniferus and M. trilobatus. Comparison of approximately 2,700-base-pair sequences of nuclear rDNA (partial 18S, complete ITS region and partial 28S) from M. texanus n. sp., M. spiniferus and M. trilobatus, strongly supports the status of M. texanus n. sp. as a new species.
KeywordsVentral Sucker Oral Sucker ITS1 Region Genital Atrium Anterior Testis
The authors sincerely thank Andres Soto (Texas A&M University, Kingsville), Stephen Curran (Gulf Coast Research Laboratory, University of Southern Mississippi) and Scott Snyder (University of Nebraska at Omaha) for their help in the field. Eric Hoberg and Patricia Pillitt arranged a loan of type and voucher specimens from the U.S. National Parasite collection. This work was supported by The Systematic Research Fund of The Linnean Society of London and the Systematics Association (UK) for Vasyl Tkach and LeAnne Froese, and ND EPSCoR AURA (Advanced Undergraduate Research Assistanships) for Eric Strand. All experiments and procedures described in this publication were in compliance with current laws of the states in which they were performed.
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