THE BIOLOGY AND SYSTEMATICS OF A NEW SPECIES OF RIBBON WORM, GENUS TUBULANUS (PHYLUM NEMERTEA) By Rebecca Kirk Ritger Submitted to the Faculty of the College of Arts and Sciences of American University in Partial Fulfillment of the Requirements for the Degree of Master of Science In Biology Chair: Dr. Qiristopher'Tudge m Dr.David C r. Jon L. Norenburg Dean of the College of Arts and Sciences JuK4£ __________ Date 2004 American University Washington, D.C. 20016 AMERICAN UNIVERSITY LIBRARY 1 1 0 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number: 1421360 INFORMATION TO USERS The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. ® UMI UMI Microform 1421360 Copyright 2004 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. THE BIOLOGY AND SYSTEMATICS OF A NEW SPECIES OF RIBBON WORM, GENUS TUBULANUS (PHYLUM NEMERTEA) By Rebecca Kirk Ritger ABSTRACT Most nemerteans are studied from poorly preserved museum specimens. Much of the existing data on this group of worms is incomplete at best. Only through thorough species descriptions from live animals and properly preserved specimens will we be able to reconstruct the life history relationships of this cryptic group of worms. Since nemerteans generally have very few distinctive external characters, the primary source of data used for species descriptions and phylogenetic reconstruction comes from internal morphology based on histological slide material. The goal of this project is the preparation of properly stained and sectioned material used to compare species in this particular genus. A new species of Tubulanus (Tubulanidae: Palaeonemertea: Nemertea) from southern Florida and Belize is described and illustrated. This study adds important infor­ mation about anatomy and life history and yields the most comprehensive description of a palaeonemertean. This description serves as the baseline for a preliminary phylogenetic analysis of the genus. ii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS ABSTRACT....................................................................................................................... ii TABLE OF CONTENTS.................................................................................................. iii LIST OF TABLES............................................................................................................ vi LIST OF FIGURES..........................................................................................................vii Chapter 1. INTRODUCTION .......................................................... 1 Phylum Nemertea.................................................................................................... 1 Nemertean Taxonomy and Systematics.................................................................. 1 Palaeonemertean Systematics................................................................................. 3 Genus Tubulanus....................................................................................................3 Nemertean Anatomy and Development.................................................................. 5 Purpose of Study.....................................................................................................7 2. MATERIALS AND METHODS ............................................................... 9 Specimen Collection................................................................................ 9 Histology............................................................................................................. 10 Pre-fixation treatment........................................................................................10 Fixation..............................................................................................................11 Washing ................................................................................................ 12 Dehydrating ............. 13 iii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Clearing............................................................................................................. 13 Infiltrating with paraffin...................................................................................13 Sectioning.........................................................................................................14 Staining.............................................................................................................15 Electron Microscopy............................................................................................. 17 Light Microscopy vs. Electron Microscopy...................................................... 17 Scanning electron microscopy.......................................................................... 17 Transmission electron microscopy................ 19 3. RESULTS...........................................................................................................24 Anatomy Summary...............................................................................................24 External morphology............................................................................................24 Body wall.............................................................................................................. 25 Proboscis ...............................................................................................................26 Brain organization.................................................................................................27 Cerebral sensory organs........................................................................................ 27 Lateral sensory organs.......................................................................................... 28 Nephridial system................................................................................................. 28 A New Species of Palaeonemertean, Tubulanus riceae n. sp. (Nemertea), from South Florida and Belize............................................................... 29 Materials and Methods................................................. 29 Systematic Account .................................................................................... 29 Description.............. 31 iv Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Preliminary Phylogenetic Analysis of the GenusTubulanus ...........................59 4. DISCUSSION............................................................................................... 60 Tubulanus Systematics..........................................................................................60 Character Modification Justification.....................................................................65 Color.................................................................................................................65 Rhynchocoel villus............................................................................................66 Fixation artifact in anterior region....................................................................66 Head wider than body.......................................................................................66 Glandular cell types in the midgut/lateral sensory organs region.....................67 Eyes...................................................................................................................67 5. CONCLUSIONS AND FUTURE RESEARCH GOALS.................................... 71 Appendix A. LIST OF CHARACTERS AND THEIR STATES.............................................. 73 B. CHARACTER MATRIX FOR THE GENUS TUBULANUS ............................. 81 C. LIST OF TUBULANUS SPECIES BY LOCALITY............................................ 85 D. LIST OF TUBULANUS SPECIES DISTRIBUTION....................... 88 E. RECIPES FOR HISTOLOGICAL AND TEM PREPARATION....................... 92 REFERENCES.............. 93 v Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF TABLES Table 1. The palaeonemertean species included in the phylogenetic analysis vi Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF FIGURES Figure 1. Tubulanus riceae n. sp. Drawing of complete individual in dorsal aspect....................8 2. Tubulanus riceae n. sp. in its tube................................................................................ 44 3. Tubulanus rhabdotus....................................................................................................45 4. Tubulanus pellucidus, T. rhabdotus, and T. riceae