Fiddler Crabs Home Blog


The following information is an expansion and update of that found in:

Rosenberg, M.S. 2001. The systematics and taxonomy of fiddler crabs: A phylogeny of the genus Uca. Journal of Crustacean Biology 21(3):839-869.

Additional references for updated information will be detailed below.

A Note on Classification

Shih et al. (2016) published a paper which uses a phylogenetic tree showing ghost crabs as a subgroup of fiddler crabs to justify splitting fiddler crabs into eleven different genera (essentially, raising the subgenera listed below to genera, except for Australuca which they find to be a subset of Tubuca). While one can argue whether differences among the subgroups warrant being considered genera or subgenera, I do not believe the phylogenetic tree which they use to justify this change is correct and for now am sticking with the more traditional approach of keeping all fiddler crabs within a single genus on this website. I will update this site to match their classification if additional data and future analyses continue to support their result.

Genus Uca Leach, 1814

Type species: Cancer vocans major Herbst, 1782

The earliest description of the type species of Uca is from a drawing in Seba (1758), which he called Cancer uka una, Brasiliensibus (shown below).

Seba's fiddler crab image

A number of authors subsequently used this same picture as a basis for naming the species (Manning & Holthuis 1981). Cancer vocans major Herbst, 1782; Ocypode heterochelos Lamarck, 1801; Cancer uka Shaw and Nodder, 1802; and Uca una Leach, 1814, are all objective synonyms, because they are all based on the picture and description from Seba. Because of this, the official type specimen of the genus Uca is Cancer vocans major. The earliest description of this species based on actual specimens and not on Seba's drawing was Gelasimus platydactylus Milne-Edwards, 1837.

As an aside, Seba's name, Cancer uka una comes from the nomenclature of Marcgrave (1648), who mispelled “uça una” as “uca una”. Not only did Seba copy the mispelling, but he applied it to the fiddler crab instead of the mangrove crab (which is today called Ucides) to which Marcgrave applied the name (see below). Latreille's (1817) proposal of the generic name Gelasimus for fiddler crabs was so that Uca could be applied to mangrove crabs; as this was an invalid proposal, Uca is retained for fiddlers, despite being due to a pair of errors (Tavares 1993).
Marcgrave's Maracoani image
Oldest known drawing of a fiddler crab (Marcgrave 1648). He labeled it “Maracoani”, and it represents the namesake of the species Uca maracoani.
Marcgrave's Uca una image
The drawing actually labeled “Uca Una” by Marcgrave (1648) is not a fiddler crab. Today this species is known as the mangrove crab Ucides cordatus.
Marcgrave's Ciecie Ete image
The other fiddler crab drawing found in Marcgrave (1648), labeled “Ciecie Ete” (he also refers to a very similar species called “Ciecie Panema”). This figure is believed to most likely represent Uca thayeri.

For about 60 years, the genus was known as Gelasimus, until Rathbun (1897) showed that the abandonment of the older name Uca did not conform to zoological naming conventions. The type species of Uca was known as both Uca heterochelos and U. platydactylus, until Rathbun (1918) suggested the adoption of U. heterochelos as the valid name. Almost 50 years later, Holthuis (1962) pointed out that U. heterochelos was an objective junior synonym of U. major, thus the type species has been referred to as U. major ever since.

However, Bott (1973) discovered that there has been a universal misinterpretation of the type species; the species pictured by Seba is not the American species commonly referred to as U. major, but rather the West African/Portuguese species called U. tangeri (Eydoux, 1835). Correcting this error would have caused a somewhat painful change of names (Holthuis 1979; Manning & Holthuis 1981). The type species would still be called U. major, but would refer to the West African/European species rather than the American one; the American species, which has been called U. major since 1962, would be called U. platydactylus, a name not used since 1918.

To deal with this dilemma, the Society of Zoological Nomenclature officially designated the holotype of Gelasimus platydactylus as a neotype of Cancer vocans major (Holthuis 1979; ICZN 1983). The result of this decision is that we retain the names U. major for the American species and U. tangeri for the West African/European species. It also means that although U. tangeri is technically the species upon which the genus is named, U. major (Cancer vocans major) is still the official type species of the genus Uca.


There have been two major proposals for splitting up the genus, one by Bott (1973) and the other by Crane (1975). Neither is based on a numerical phylogeny. Crane's descriptions are very complete. Bott's descriptions are poor, but have priority. For a long time, scientists actively ignored both subdivisions and when there was a reference in the literature, it almost always used Crane's names and not Bott's. Bott also split the genus into multiple genera rather than subgenera, an unnecessary complication in most researcher's minds.

Rosenberg (2001) partly cleared up the confusion between the two systems. More recent work by Beinlich & von Hagen (2006), Shih et al. (2009), Spivak & Cuesta (2009), Naderloo et al. (2010), Landstorfer & Schubart (2010), and Shih (2015) have continued to refine the subgenera as detailed below.

Subgenus Uca Leach, 1814

Uca major
All Species
Uca antiqua , Uca heteropleura, Uca insignis, Uca intermedia, Uca major, Uca maracoani, Uca marinae , Uca monilifera, Uca oldroydi , Uca ornata, Uca princeps, Uca stylifera

This subgenus is equivalent to Crane's Uca. U. tangeri is sometimes placed in this subgenus and sometimes placed in its own monotypic subgenus (below).

Subgenus Afruca Crane, 1975

Uca tangeri
All Species
Uca miocenica , Uca tangeri

This monotypic subgenus consists of the single species U. tangeri. It is sometimes combined into the subgenus Uca.

Subgenus Minuca Bott, 1954

Uca mordax
All Species
Uca brevifrons, Uca burgersi, Uca ecuadoriensis, Uca galapagensis, Uca hamlini , Uca herradurensis, Uca longisignalis, Uca marguerita, Uca minax, Uca mordax, Uca osa, Uca panacea, Uca pugilator, Uca pugnax, Uca pygmaea, Uca rapax, Uca subcylindrica, Uca thayeri, Uca umbratila, Uca victoriana, Uca virens, Uca vocator, Uca zacae

This subgenus is largely equivalent to a combination of Crane's Minuca and Boboruca. I have also included U. pugilator and U. panacea, which Crane placed with the Leptuca.

Subgenus Leptuca Bott, 1973

Uca stenodactylus
All Species
Uca argillicola, Uca batuenta, Uca beebei, Uca coloradensis, Uca crenulata, Uca cumulanta, Uca deichmanni, Uca dorotheae, Uca festae, Uca helleri, Uca inaequalis, Uca latimanus, Uca leptodactyla, Uca limicola, Uca musica, Uca oerstedi, Uca saltitanta, Uca speciosa, Uca spinicarpa, Uca stenodactylus, Uca tallanica, Uca tenuipedis, Uca terpsichores, Uca tomentosa, Uca uruguayensis

This subgenus is largely equivalent to Crane's Celuca, without any of the Indo-West Pacific species. This subgenus is certainly paraphyletic and quite possibly polyphyletic. It is essentially the catch-all group for any broad-fronted American species which is not part of the Minuca.

Subgenus Austruca Bott, 1973

Uca lactea
All Species
Uca albimana, Uca annulipes, Uca bengali, Uca cryptica, Uca iranica, Uca lactea, Uca mjoebergi, Uca occidentalis, Uca perplexa, Uca triangularis

This subgenus is the U. lactea species complex (formerly part of Crane's Celuca), plus a few recently identified/resurrected species.

Subgenus Paraleptuca Bott, 1973

Uca chlorophthalmus
All Species
Uca boninensis, Uca chlorophthalmus, Uca crassipes, Uca sindensis, Uca splendida

This subgenus is roughly equivalent to Crane's Amphiuca, minus U. inversa.

Subgenus Cranuca Beinlich & von Hagen, 2006

Uca inversa
All Species
Uca inversa

This monotypic subgenus consists of the single species U. inversa.

Subgenus Gelasimus Latreille, 1817

Uca vocans
All Species
Uca borealis, Uca dampieri, Uca excisa, Uca hesperiae, Uca jocelynae, Uca tetragonon, Uca vocans, Uca vomeris

This subgenus is equivalent to Crane's Thalassuca, minus U. formosensis.

Subgenus Tubuca Bott, 1973

Uca urvillei
All Species
Uca acuta, Uca arcuata, Uca capricornis, Uca coarctata, Uca demani, Uca dussumieri, Uca flammula, Uca forcipata, Uca paradussumieri, Uca rhizophorae, Uca rosea, Uca typhoni, Uca urvillei

This subgenus is equivalent to Crane's Deltuca.

Subgenus Australuca Crane, 1975

Uca bellator
All Species
Uca bellator, Uca elegans, Uca hirsutimanus, Uca longidigitum, Uca polita, Uca seismella, Uca signata

This subgenus is essentially unchanged from Crane's original description, except for the addition of a few species described after the original designation.

Subgenus Xeruca Shih, 2015

Uca formosensis
All Species
Uca formosensis

This monotypic subgenus consists of the single species U. formosensis.

Subgenus Petruca Shih et al., 2015

Uca panamensis
All Species
Uca panamensis

This monotypic subgenus consists of the single species U. panamensis.

Species Level Systematics

For an overview of all Uca species, the best reference is Crane (1975); any earlier major work would be overridden by Crane's descriptions. For the most part, the taxa recognized by Crane are still accepted today. A number of new species have been described since the publication of her monograph, a few species has been discovered to be invalid, and two of her new species were previously described by Bott (1973); as with the subgenera, his names have priority and take precedence. These changes are summarized below.

Changes to the species level taxonomy of the genus Uca since Crane (1975)

New/Validated Extant Species Reference(s)
Uca panacea Novak & Salmon (1974)
Uca marguerita Thurman (1981)
Uca elegans George & Jones (1982)
Uca hirsutimanus George & Jones (1982)
Uca intermedia von Prahl & Toro (1985)
Uca victoriana von Hagen (1987)
Uca albimana Kossmann (1877), Shih et al. (2009), Naderloo et al. (2010)
Uca iranica Pretzmann (1971), Shih et al. (2009), Naderloo et al. (2010)
Uca cryptica Naderloo et al. (2010)
Uca osa Landstorfer & Schubart (2010)
Uca jocelynae Shih et al. (2010)
Uca splendida Stimpson (1858), Shih et al. (2012)
Uca boninensis Shih et al. (2013)
Junior Subsynonym Correct Name Reference(s)
Uca australiae Uca demani George & Jones (1982)
Uca minima Uca signata George & Jones (1982)
Uca pavo Uca capricornis von Hagen & Jones (1989)
Uca spinata Uca paradussmieri Dai & Yang (1991), Jones & Morton (1994)
Uca pacificensis Uca excisa Unpublished
Uca leptochela Uca festae Beinlich & von Hagen (2006)
Incorrect Spelling Correct Spelling Reference(s)
Uca longidigita Uca longidigitum von Hagen & Jones (1989)
Uca mjobergi Uca mjoebergi von Hagen & Jones (1989)

Crane (1975) tended to lump related taxa into subspecies rather than treat them as distinct species. A number of studies since that time have raised virtually all of her subspecies to specific status (e.g., Barnwell 1980; Barnwell & Thurman 1984; Collins et al. 1984; Green 1980; Salmon et al. 1979; Salmon & Kettler 1987; Thurman 1979; Thurman 1982; von Hagen & Jones 1989). It has become common practice with many authors to ignore all of the subspecific designations and treat each as a separate species (e.g., George & Jones 1982; Jones & Morton 1994; von Hagen & Jones 1989). I follow this practice throughout this website.