Keywords
Neognathostomata; Cassiduloida; morfometría; México.
How to Cite
Abstract
ntroduction: In Mexico, there are two recorded living species of Cassiduloida: Cassidulus caribaearum and Rhyncholampas pacifica. Most of the taxonomic studies on cassiduloids have used external morphology, pedicellariae and morphometric characters; however, the intraspecific variation of quantitative and qualitative characters has been poorly evaluated. Objective: To compare the basic morphology of R. pacifica and C. caribaearum. Methods: We examined a total of 2 158 specimens of R. pacifica and C. caribaearum, selecting 50 to evaluate shape and size with linear regression and Principal Component analysis. We selected an additional 62 specimens per species to identify significant character correlations and morphological groups within species. Results: There is a direct relationship between Test length and Test width. Test height/Test width, and Total length (oral view)/Distance from the ambitus to the peristome apex, are the two main ratios to distinguish both species. C. caribaearum is more dorsoventrally compressed and has a round peristome base; versus R. pacifica has a tall and triangular one. There are four morphological groups of C. caribaearum and two groups for R. pacifica. Conclusions: These two species can be distinguished with reliable morphological characters, in which peristome shape suggests that R. pacifica is more adapted to burrowing deeper into certain types of substratum.
References
Agassiz, A. (1869). Preliminary report on the Echini and star-fishes dredged in deep water between Cuba and the Florida Reef, by L.F. de Pourtales, Assist. U.S. Coast Survey. Bulletin of the Museum of Comparative Zoölogy at Harvard College, 1, 253-308.
Agassiz, A. (1872). Revision of the echini. Memoirs of the Museum of Comparative Zoology, 3, 383-762.
Boivin, S., Saucède, T., Laffont, R., Steimetz, E., & Neige, P. (2018). Diversification rates indicate an early role of adaptive radiations at the origin of modern echinoid fauna. PLoS ONE, 13(4), e0194575.
Borrero-Pérez, G.H., Benavides-Serrato, M., & Diaz-Sanchez, C.M. (2012). Equinodermos del Caribe colombiano II: Echinoidea y Holothuroidea. Santa Marta, Colombia: Serie de Publicaciones Especiales de Invemar No. 30.
Buitrón-Sánchez, B.E., Solís-Marín, F.A., Conejeros-Vargas, C.A., & Caballero-Ochoa, A.A. (2019). Equinodermos de las familias Echinolampadidae Gray, 1851 y Cassidulidae L. Agassiz y Desor, 1847 fósiles y recientes de México: estudio comparativo con base en macro y microestructuras. Paleontología Mexicana, 8(1), 51-63.
Caballero-Ochoa, A.A., Martínez-Melo, A., Conejeros-Vargas, C.A., Solís-Marín, F.A., & Laguarda-Figueras, A. (2017). Diversidad, patrones de distribución y “hotspots” de los equinoideos irregulares (Echinoidea: Irregularia) de México. Revista Biología Tropical, 65(1), S42-S59.
Carter, B.D., & Beisel, T.H. (1987). “Cassidulus” trojanus belongs in the genus Eurhodia (Echinoidea) based upon new criteria. Journal of Paleontology, 61(5), 1080-1083.
Ciampaglio, C.N., & D’Orazio, A.E. (2007). Heterochrony within the cassiduloid echinoids from the Castle Hayne Limestone of southeastern North Carolina. Historical Biology: An International Journal of Paleobiology, 19(4), 301-313.
Clark, H.L. (1925). Marine Zoology of Tropical Central Pacific: Echinoderms other than sea-stars. Bulletin of the Bernice Pauahi Bishop Museum, 27, 89-111.
Gladfelter, W.B. (1978). General ecology of the cassiduloid urchin Cassidulus caribbearum. Marine Biology, 47, 149-160.
Hartigan, J.A., & Wong, M.A. (1979). Algorithm AS 136: A K-means clustering algorithm. Journal of the Royal Statistical Society, Series C, Applied Statistics, 28(1), 100-108.
Kier, P.M. (1962). Revision of the cassiduloid echinoids. Smithsonian Miscellaneous Collections, 144(3), 1-262.
Kier, P.M. (1974). Evolutionary trends and their functional significance in the post-Paleozoic echinoids. Journal of Paleontology, 48(S5), 1-95.
Kier, P.M. (1975). The echinoids of Carrie Bow Cay, Belize. Smithsonian Contributions to Zoology, 206, 1-45.
Lawrence, J.M., & Cobb, J. (2017). Validation of Astropecten jarli Madsen, 1950 and implications for A. cingulatus Sladen, 1883 (Paxillosida: Astropectinidae). Zootaxa, 4269(1), 101-114.
Lê, S., Josse, J., & Husson, F. (2008). FactoMineR: An R Package for Multivariate Analysis. Journal of Statistical Software, 25(1), 1-18.
MacLeod, N. (2017). Morphometrics: History, development methods and prospects. Zoological Systematics, 42(1), 4-33.
Martínez-Melo, A. (2008). Relación heterocrónica entre Rhyncholampas pacificus (A. Agassiz, 1863) y Cassidulus caribaearum Lamarck, 1801. (Master’s thesis). Universidad Nacional Autonoma de Mexico, Mexico City, Mexico.
Martínez-Melo, A., De Luna, E., & Buitrón-Sánchez, B.E. (2017). Morfometría de los equinoideos de la familia Cassidulidae (Echinoidea: Cassiduloida). Revista de Biología Tropical, 65(1), S233-S243.
McKinney, M.L. (1984). Allometry and heterochrony in an Eocene echinoid lineage: morphological change as by-product of size selection. Paleobiology, 10(4), 407-419.
McKinney, M.L. (1986). Ecological causation of heterochrony: a test and implications for evolutionary theory. Paleobiology, 12(3), 282-289.
McNamara, K., Pawson, D., Miskelly, A., & Byrne, M. (2017). Class Echinoidea. In M. Byrne, & T.D. O´Hara (Eds.), Australian Echinoderms: Biology, Ecology and Evolution (pp. 351-445). Clayton South: CSIRO Publishing.
Mooi, R. (1990). Living cassiduloids (Echinodermata: Echinoidea): a key and annotated list. Proceedings of the Biological Society of Washington, 103(1), 63-85.
Ocakoglu, G., & Ercan, I. (2013). Traditional and modern morphometrics: review. Turkiye Klinikleri Journal of Biostatistics, 5(1), 37-41.
R Core Team. (2019). R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing. Vienna, Austria. Retrieved from http://www.r-project.org
Remagnino, P., Mayo, S., Wilkin, P., Cope, J., & Kirkup, D. (2016). Morphometrics: a brief review. In P. Remagnino, S. Mayo, P. Wilkin, J. Cope, & D. Kirkup, D. (Eds.), Computational Botany (pp. 11-32). Germany: Springer-Verlag Berlin Heidelberg.
Saitoh, M., & Kanazawa, K. (2012). Adaptative morphology for living in shallow water environments in spatangoid echinoids. Zoosymposia, 7, 255-265.
Schultz, H.A.G. (2017). Echinoidea. Vol. 2, Echinoidea with bilateral symmetry. Irregularia. In A. Schmidt-Rhaesa (Ed.), Handbook of Zoology-Handbuch der Zoologie (pp. 1-359). Hemdingen, Germany: De Gruyter.
Solís-Marín, F.A., Alvarado, J.J., Abreu-Pérez, M., Aguilera, O., Alió, J., Bacallado-Aránega, J.J., Barraza, E., … Williams, S.M. (2013). Appendix: A.1 Taxonomic list of the Echinoderms of the Pacific coast of Latin America. In J.J. Alvarado & F.A. Solís-Marín (Ed.), Echinoderm Research and Diversity in Latin America (pp. 544-601). Berlin, Heidelberg: Springer.
Solís-Marín, F.A., Caballero-Ochoa, A.A., Laguarda-Figueras, A., & Durán-González, A. (2017). Catálogo de Autoridades Taxonómicas de los Equinodermos de México. Ciudad de México, México: Instituto de Ciencias del Mar y Limnología (ICML), Universidad Nacional Autónoma de México (UNAM). Informe final, SNIB-CONABIO, proyecto No. Z002.
Souto, C., & Martins, L. (2018). Synchrotron micro-CT scanning leads to the discovery of a new genus of morphologically conserved echinoid (Echinodermata: Cassiduloida). Zootaxa, 4457(1), 70-92.
Souto, C., Mooi, R., Martins, L., Menegola, C., & Marshall, C.R. (2019). Homoplasy and extinction: the phylogeny of cassidulid echinoids (Echinodermata). Zoological Journal of the Linnean Society, 187, 622-660.
Suter, S.J. (1988). The decline of the cassiduloids: merely bad luck? Victoria: Proceedings of the International Echinoderms Conference.
Comments
This work is licensed under a Creative Commons Attribution 4.0 International License.