Gonadal morphology of the weedy seadragon, Phyllopteryx taeniolatus (Lacépède): characterisation of ovarian and testicular maturation
K. L. Forsgren A B C and K. A. Young AA Department of Biological Sciences, California State University – Long Beach, Long Beach, CA 90840, USA.
B Current address: School of Aquatic and Fisheries Sciences, University of Washington, 1122 NE Boat Street, Box 355020, Seattle, WA 98195, USA.
C Corresponding author. Email: klforsg@u.washington.edu
Australian Journal of Zoology 56(6) 441-446 https://doi.org/10.1071/ZO08031
Submitted: 21 March 2008 Accepted: 24 February 2009 Published: 24 March 2009
Abstract
Because little is known about the reproductive biology of the weedy seadragon, Phyllopteryx taeniolatus, we sought to characterise for the first time the morphology and histology of the gonads of female and male weedy seadragons. Each seadragon ovary consisted of a pair of cylindrical tubes with a total of four tubes per female with follicles arranged with less mature oocytes originating from the germinal ridge and progressively more advanced oocytes occurring in a spiral fashion around the periphery of less-developed oocytes. Seadragon testes had a system of interconnecting seminiferous tubules with spermatocyte development occurring within the tubule. Spermatocytes were observed along the testis wall and appeared to emerge into the lumen where further development of spermatocytes occurred. This study represents the first examination of the gonadal structures of the weedy seadragon, a species currently classified by the International Union for Conservation of Nature (IUCN) as ‘Near Threatened’. The descriptions of morphological development of the gonads may be useful in the histological identification of the stages of gametogenesis and reproductive status of other syngnathids. In addition, this information may also provide useful information in elucidating the phylogeny of this family of fishes.
Acknowledgements
We thank the Aquarium of the Pacific for their support and access to their weedy seadragon collection. Special thanks to Dr C. Lowe and Dr G. Young for their continued support. We also thank: Sigma Xi Grants-in-Aid of Research (KLF), Boeing-CNSM Graduate Scholarship (KLF), and NSF MRI 0421441 (KAY) that provided funding for this project.
Ah-King, M. , Elofsson, H. , Kvarnemo, C. , Rosenqvist, G. , and Berglund, A. (2006). Why is there no sperm competition in a pipefish with externally brooding males? Insights from sperm activation and morphology. Journal of Fish Biology 68, 958–962.
| Crossref | GoogleScholarGoogle Scholar |
Forsgren, K. L. , and Lowe, C. G. (2006). The life history of weedy seadragons, Phyllopteryx taeniolatus (Teleostei: Syngnathidae). Marine and Freshwater Research 57, 313–322.
| Crossref | GoogleScholarGoogle Scholar |
Foster, S. , and Vincent, A. (2004). Life history and ecology of seahorses: implications for conservation and management. Journal of Fish Biology 65, 1–61.
| Crossref | GoogleScholarGoogle Scholar |
Grier, H. J. (1981). Cellular organization of the testis and spermatogenesis in fishes. American Zoologist 21, 345–357.
Herald, E. S. (1959). From pipefish to seahorse: a study of phylogenetic relationships. Proceedings of the California Academy of Sciences 24, 465–473.
Kvarnemo, C. , and Simmons, L. W. (2004). Testes investment and spawning mode in pipefishes and seahorses (Syngnathidae). Biological Journal of the Linnean Society 83, 369–376.
| Crossref | GoogleScholarGoogle Scholar |
Kvarnemo, C. , Simmons, L. W. , Ah-King, M. , and Elofsson, H. (2003). The myth of the sperm cloud – or why is testes size not affected by spawning mode in seahorses and pipefishes. Journal of Fish Biology 63(Supplement A), 235.
| Crossref | GoogleScholarGoogle Scholar |
Lyons, D. O. , and Dunne, J. J. (2003). Reproductive costs to male and female worm pipefish. Journal of Fish Biology 62, 767–773.
| Crossref | GoogleScholarGoogle Scholar |
Masonjones, H. D. , and Lewis, S. M. (1996). Courtship behaviour in the dwarf seahorse, Hippocampus zosterae. Copeia 1996, 634–640.
| Crossref | GoogleScholarGoogle Scholar |
McCoy, E. E. , Jones, A. G. , and Avise, J. C. (2001). The genetic mating system and tests for cuckoldry in a pipefish species in which males fertilize eggs and brood offspring externally. Molecular Ecology 10, 1793–1800.
| Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |
Miranda-Marure, M. E. , Martínez-Pérez, J. A. , and Brown-Peterson, N. J. (2004). Reproductive biology of the opossum pipefish, Microphis brachyurus lineatus, in Tecolutla Estuary, Veracruz, Mexico. Gulf and Caribbean Research 16, 101–108.
Parenti, L. R. , and Grier, H. J. (2004). Evolution and phylogeny of gonad morphology in bony fishes. Integrative and Comparative Biology 44, 333–348.
| Crossref | GoogleScholarGoogle Scholar |
Poortenaar, C. W. , Woods, C. M. C. , James, P. J. J. , Giambartolomei, F. M. , and Lokman, P. M. (2004). Reproductive biology of female big-bellied seahorses. Journal of Fish Biology 64, 717–725.
| Crossref | GoogleScholarGoogle Scholar |
Ripley, J. L. , and Foran, C. M. (2006). Differential parental nutrient allocation in two congeneric pipefish species (Syngnathidae: Syngnathus spp.). The Journal of Experimental Biology 209, 1112–1121.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Ruby, S. M. , and McMillan, D. B. (1970). Cyclic changes in the testis of the brook stickleback Eucalia inconstans (Kirtland). Journal of Morphology 131, 447–466.
| Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |
Sanchez-Camara, J. , Booth, D. J. , and Turon, X. (2005). Reproductive cycle and growth of Phyllopteryx taeniolatus. Journal of Fish Biology 67, 133–148.
| Crossref | GoogleScholarGoogle Scholar |
Selman, K. , Wallace, R. A. , and Player, D. (1991). Ovary of the seahorse, Hippocampus erectus. Journal of Morphology 209, 285–304.
| Crossref | GoogleScholarGoogle Scholar |
Takahashi, E. , Connolly, R. M. , and Lee, S. Y. (2003). Growth and reproduction of double-ended pipefish, Syngnathoides biaculeatus, in Moreton Bay, Queensland, Australia. Environmental Biology of Fishes 67, 23–33.
| Crossref | GoogleScholarGoogle Scholar |
Tyler, C. R. , and Sumpter, J. P. (1996). Oocyte growth and development in teleosts. Reviews in Fish Biology and Fisheries 6, 287–318.
| Crossref | GoogleScholarGoogle Scholar |
Van Look, K. J. W. , Dzyuba, B. , Cliffe, A. , Koldewey, H. J. , and Holt, W. V. (2007). Dimorphic sperm and the unlikely route to fertilization in the yellow seahorse. The Journal of Experimental Biology 210, 432–437.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Vincent, A. C. J. (1995). A role for daily greetings in maintaining seahorse pair bonds. Animal Behaviour 49, 258–260.
| Crossref | GoogleScholarGoogle Scholar |
Wallace, R. A. , and Selman, K. (1981). Cellular and dynamic aspects of oocyte growth in teleosts. American Zoologist 21, 325–343.
Watanabe, S. , Hara, M. , and Watanabe, Y. (2000). Male internal fertilization and introsperm-like sperm of the seaweed pipefish (Syngnathus schlegeli). Zoological Science 17, 759–767.
| Crossref | GoogleScholarGoogle Scholar |
Wilson, A. , Vincent, A. , Ahnesjo, I. , and Meyer, A. (2001). Male pregnancy in seahorses and pipefishes (Family Syngnathidae): rapid diversification of paternal brood pouch morphology inferred from a molecular phylogeny. The Journal of Heredity 92, 159–166.
| Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |
Wilson, A. B. , Ahnesjo, I. , Vincent, C. J. A. , and Meyer, A. (2003). The dynamics of male brooding, mating patterns, and sex roles in pipefishes and seahorses (Family Syngnathidae). Evolution 57, 1374–1386.
| PubMed |
