Abstract
Lobithelphusa Rodriguez, 1982 is endemic to southern Mexico. Assigned to this monotypic genus is the freshwater pseudothelphusid crab, L. mexicana Rodriguez, 1982. The original description based on an old, dry, male specimen in the collections of the Natural History Museum, London, is brief and the crab was only partially figured. Lobithelphusa mexicana has subsequently never been recorded from Mexico and, consequently, the conservation status of this species is unknown. The type specimen has a complete, but detached left chela; is devoid of the left ambulatory pereiopods 1–3, with the fourth missing the carpus, propodus and dactylus; and its left first gonopod detached but retained in a glass tube kept adjacent to the crab. In spite of this damage the crab is still in remarkably good condition for a specimen registered in 1860. The purpose of this study is to apply computed tomography (CT) scanning techniques on the extant type, including its first gonopod, in order to provide detailed illustrations of the crab. These, in turn, shall be used to re-describe the species in order to help establish the current distribution status of L. mexicana in Mexico, and clarify its systematic position within the Pseudothelphusidae Ortmann, 1893.
References
Alvarez, F. (1989) Smalleyus tricristatus, new genus, new species, and Pseudothelphusa parabelliana, new species (Brachyura: Pseudothelphusidae) from Los Tuxtlas, Veracruz, Mexico. Proceedings of the Biological Society of Washington, 102 (1), 45−49.
Alvarez, F. & Villalobos, J.L. (2016) Freshwater decapod diversity and conservation in Mexico. In: Kawai, T. & Cumberlidge, N. (Eds.), Conservation and Biology of Freshwater Decapoda: A Global Overview. Springer, Cham, pp. 237–266.
https://doi.org/10.1007/978-3-319-42527-6_8
Alvarez, F., Villalobos J.L., Rojas, Y. & Robles, R. (1999) Listas y comentarios sobre los crustáceos decápodos de Veracruz, México. Anales del Instituto de Biología, Universidad Nacional Autónoma de México, Serie Zoología, 70 (1), 1−27.
Ball, A.D., Goral, T. & Kamanli, S.A. (2017) Confocal microscopy applied to paleontological specimens. The Paleontological Society Papers, 22, 39−55.
Bott, R. (1967) Fluß-Krabben aus dem wetlichen Mittelamerika (Crust., Decap.). Senckenbergiana Biologica, 48 (5/6), 373–380.
Campos, M.R. (2005) Freshwater crabs from Colombia. A taxonomic and distributional study. Academia Colombiana de Ciencias Exactas Físicas y Naturales. Col. Jorge Álvarez Lleras No. 24. Academia Colombiana de Ciencias Exactas, Físicas y Naturales, Bogotá, 363 pp.
Campos, M.R. & Magalhães, C. (2014) Colombiathelphusa, a new genus of freshwater crab from Colombia, a new species, and the first location record of Eidocamptophallus chacei (Pretzmann, 1967) (Crustacea: Decapoda: Pseudothelphusidae). Zootaxa, 3860 (6), 571–579.
https://doi.org/10.11646/zootaxa.3860.6.5Cumberlidge, N., Álvarez, F. & Villalobos, J.L. (2014) Results of the global conservation assessment of the freshwater crabs: The Neotropical region (Brachyura: Pseudothelphusidae and Trichodactylidae), with an update on diversity. Zookeys, 457, 133−157.
https://doi.org/10.3897/zookeys.457.6598
Kamanli, S.A., Kihara, T.C., Ball, A.D., Morritt, D. & Clark, P.F. (2017) A 3D imaging and visualization workflow, using confocal microscopy and advanced image processing for brachyuran crab larvae. Journal of Microscopy, 266 (3), 307−323.
https://doi.org/10.1111/jmi.12540
Koch, M., Kamanli, S.A., Crimmen, O., Lin, C.W., Clark, P.F. & Ďuriš, Z. (2017) The identity of Monomia argentata (Crustacea: Brachyura: Portunidae) resolved by X-ray, computed tomography scanning and molecular comparisons. Invertebrate Systematics, 31, 797−811.
https://doi.org/10.1071/IS16058
Limaye, A. (2012) Drishti: a volume exploration and presentation tool. In: Stock, S.R. (Ed.), Developments in X-Ray Tomography VIII. Proceedings of SPIE Vol. 8506 SPIE. Bellingham, Washington, pp. 1–9.
Ng, P.K.L. & Low, M.E.Y. (2010) On the generic nomenclature of nine brachyuran names, with four replacement names and two nomina protecta (Crustacea: Decapoda). Zootaxa, 2489 (1), 34–46.
https://doi.org/10.11646/zootaxa.2489.1.2
Ng, P.K.L., Guinot, D. & Davie, P.J.F. (2008) Systema Brachyurorum: Part I. An annotated checklist of extant brachyuran crabs of the world. Raffles Bulletin of Zoology, 17 (Supplement), 1–286.
Ojeda-Escoto, J.C. (2017) Sistemática y biogeografía de los cangrejos de agua dulce de México de la familia Pseudothelphusidae (Crustacea: Decapoda). Ph.D. Dissertation, Posgrado en Ciencias Biológicas, Instituto de Biología, Universidad Nacional Autónoma de México, Mexico City, 124 pp.
Ojeda-Escoto, J.C., Villalobos, J.L. & Alvarez, F. (2017) Three new species of freshwater crabs of the genus Pseudothelphusa (De Saussure, 1857) (Crustacea: Decapoda: Pseudothelphusidae) from Mexico. Zootaxa, 4216 (6), 559−571.
https://doi.org/10.11646/zootaxa.4216.6.3
Ortmann, A. (1893) Die Decapoden-Krebse des Strasbourg Museums, mit besonderer bërucksichtingung der von Herrn Dr. Döderlein bei Japan und bei den Liu-Kiu-Inseln gesammelten und zur Zeit im Strassburger Museum aufbewahrten Formen. VII. Theil. Abtheilung: Brachyura (Brachyura genuina Boas) II. Unterabtheilung: Cancroidea, 2. Section: Cancrinea, 1. Gruppe: Cyclometopa. Zoologische Jahrbücher Abtheilung für Systematik, Geographie und Biologie der Thiere, 7, 411–495.
Ortmann, A. (1897) Carcinologishe Stuiden. Zoologische Jahrbücher Abtheilung für Systematik, Geographie und Biologie der Thiere, 10, 258–372.
Pearse, A.S. (1911) Report on the Crustacea collected by the University of Michigan. Walker expedition in the state of Vera Cruz, Mexico. Reports of the Michigan Academy Science, 13, 108–112.
Poettinger, T.S., Klaus, S. & Schubart, C.D. (2016) Phylogenetic relationships among Neotropical freshwater crabs of the Pseudothelphusidae (Decapoda, Brachyura) and the taxonomic position of Ptychophallus and related genera. Crustaceana, 89 (14), 1717–1728.
https://doi.org/10.1163/15685403-00003627
Pretzmann, G. (1965) Vorläufiger Bericht über die Familie Pseudothelphusidae. Anzeiger der Mathematisch-Naturwissenschaftlichen Klasse der Österreichische Akademie der Wissenschaften, 1965 (1), 1–10.
Pretzmann, G. (1971) Fortschritte in der Klassifizierung der Pseudothelphusidae. Aus den Sitzungsberichten der Österreichische Akademie der Wissenschaften, 179 (8), 15–24.
Pretzmann, G. (1972) Die Pseudothelphusidae (Crustacea Brachyura). Zoologica, Stuttgart, 42 (120), 1−182.
Pretzmann, G. (1977) Zur Taxonomie, Chorologie und Systematik der mittelandischen Hypolobocerini. Sitzungsberichten der Österreichischen Akademie der Wissenschaften, Mathematisch Naturwissenschaftliche Klasse, Abt. 1 (186), 429–439.
Rathbun, M.J. (1893) Descriptions of new species of American freshwater crabs. Proceedings of the United States National Museum, 16 (959), 649–661.
https://doi.org/10.5479/si.00963801.16-959.649
Rodriguez, G. (1980) Description preliminaire de quelques espéces et genres nouveaux de crabes d’eau douce de I’Amerique tropicale (Crustacea, Decapoda, Pseudothelphusidae). Bulletin du Museum nationale d’Histoire naturelle, Paris, 4° Série, 2, Section A (3), 889–894.
Rodriguez, G. (1982) Les crabes d’eau douce d’Amérique: Famille des Pseudothelphusidae. Faune Tropicale, 12, 1−225.
Rodríguez, G. & López, B. (2003) Insular species of Neotropical freshwater crabs (Crustacea: Brachyura). Journal of Natural History, 37, 2599–2614.
https://doi.org/10.1080/00222930210155710
Rodríguez, G. & Smalley, A. (1972) Los cangrejos de agua dulce de México de la familia Pseudothelphusidae (Crustacea, Brachyura). Anales del Instituto de Biología Universidad Nacional Autónoma de México, 40 (1), 69–112.
Rodríguez, G. & Suárez, H. (2004) A revision of the freshwater crabs of the family Pseudothelphusidae (Decapoda: Brachyura) from Peru with notes on the southern limits of the family. Amazoniana, 18 (1/2), 11–28.
Smalley, A. (1964a) A terminology for the gonopods of the American river crabs. Systematic Zoology, 13 (1), 28−31.
Smalley, A. (1964b) The river crabs of Costa Rica, and the subfamilies of the Pseudothelphusidae. Tulane Studies in Zoology, 12 (6), 5–13.
Smalley, A. (1970) A new genus of freshwater crabs from Guatemala, with a key to the Middle American genera (Crustacea, Decapoda, Pseudothelphusidae). American Midland Naturalist, 83 (1), 96–106.
Smalley, A. & Adkison, D.L. (1984) Disparithelphusa pecki, a new genus and species of fresh-water crab from Mexico (Brachyura: Pseudothelphusidae). Journal of Crustacean Biology, 4 (1), 127−133.
https://doi.org/10.2307/1547901
Villalobos, J.L. & Alvarez, F. (2010) Phylogenetic analysis of the Mexican freshwater crabs of the tribe Pseudothelphusini (Decapoda, Brachyura, Pseudothelphusidae). Zoological Journal of the Linnean Society, 160, 457–481.
https://doi.org/10.1111/j.1096-3642.2009.00606.x
Villalobos, J.L. & Álvarez, F. (2013) Two new genera and three new species of freshwater crabs (Crustacea: Pseudothelphusidae: Potamocarcinini) from Chiapas, Mexico. Zootaxa, 3599 (5), 457–470.
https://doi.org/10.11646/zootaxa.3599.5.3
Villalobos-Figueroa, A. (1982) Decapoda. In: Hulbert, S.H. & Villalobos-Figueroa, A. (Eds.), Aquatic biota of Mexico, Central America and the West Indies. San Diego State University, San Diego, California, pp. 215–238.
Villalobos-Hiriart, J.L. (2005) Sistemática de los cangrejos de agua dulce de México, tribu Pseudothelphusini Ortmann, 1897 (Crustacea: Decapoda: Brachyura: Pseudothelphusidae). Análisis filogenético, biogeográfico y descripción de especies nuevas. Ph.D. Dissertation, Facultad de Ciencias, Universidad Nacional Autónoma de México, 394 pp.
Villalobos-Hiriart, J.L., Cantú Díaz-Barriga A. & Lira- Fernández, E. (1993) Los crustáceos de agua dulce de México. Revista de la Sociedad Mexicana de Historia Natural, Volumen Especial, XLIV, 267−290.
Villalobos-Hiriart, J.L. & Álvarez, F. (2008) Los cangrejos de agua dulce de la familia Pseudothelphusidae (Decapoda: Brachyura: Eubrachyura) de México. Con un apéndice de las especies citadas para América hasta el 2006. In: Alvarez, F. & Rodríguez, G. (Eds.), Crustáceos de México: Estado actual de su conocimiento. UANL-PROMEP-SEP. Dirección General de Publicaciones, Universidad Autónoma de Nuevo León, México, D.F., pp. 239–299.
Yeo, D.C.J., Ng, P.K.L. Cumberlidge, N., Magalhães, C., Daniels, S.R. & Campos, M.R. (2008). Global diversity of crabs (Crustacea: Decapoda: Brachyura) in freshwater. Hydrobiologia, 595, 275−286.
https://doi.org/10.1007/s10750-007-9023-3