Fiddler Crabs Home

Systematics

Systematic Hierarchy

Family


Family Ocypodidae Rafinesque, 1815

Type
Genus Ocypode
Contains subfamilies
Subfamily Gelasiminae, Subfamily Ucinae

Fiddler Crabs are in the family Ocypodidae, along with Ghost Crabs and Mangrove Crabs.

Subfamilies

Within the Ocypodidae, there is some uncertainty as to the relationship between fiddler crabs and ghost crabs, such that at this time fiddler crabs are not all within a single named taxon to the exclusion of non-fiddler crabs. Fiddler crabs are split between two subfamilies: (1) Gelasiminae and (2) Ucinae or Ocypodinae, depending on the hypothesis of the relationship between this subset of fiddler crabs and ghost crabs one believes. If the relationship between all fiddler crabs is resolved such that they can be placed in a single group to the exclusion of ghost crabs, that group would be the single subfamily, Ucinae.


Subfamily Gelasiminae Miers, 1886

Type
Genus Gelasimus
Part of family
Family Ocypodidae
Contains supertribe
Supertribe Gelasimitae

Under current nomenclature, the subfamily Gelasiminae contains nine genera within two major subclades (two tribes within a single redundant supertribe). If all fiddler crabs are later found to be part of a single monophyletic clade, Gelasiminae would be eliminated as a subfamily in favor or Ucinae, and this group would be represented soley by the supertribe Gelasimitae.


Subfamily Ucinae Dana, 1851

Type
Genus Uca
Part of family
Family Ocypodidae
Contains supertribe
Supertribe Ucitae

Under current nomenclature, the subfamily Ucinae contains two genera (which can be viewed as within a single tribe within a single supertribe). Depending on the precise relationship between fiddler crabs and ghost crabs, it is possible that this subfamily is invalid and a junior synonym for the ghost crab subfamily Ocypodinae. On the other hand, if all fiddler crabs are later found to be part of a single monophyletic clade, Ucinae would have priority as the name that represented the entirety of fiddlers (and thus eliminating the subfamily Gelasiminae).

Supertribes

Under the current taxonomic system of two subfamilies, the supertribes are unnecessary/redundant as each subfamily would contain only a single supertribe. These supertribes become more important if fiddler crabs are reduced to a single subfamily.


Supertribe Gelasimitae Miers, 1886

Type
Genus Gelasimus
Part of subfamily
Subfamily Gelasiminae
Contains tribes
Tribe Gelasimini, Tribe Minucini

The supertribe Gelasimitae contains two tribes. Under current nomenclature it is redundant/identical in content with the subfamily Gelasiminae, but could serve an important nomenclatural purpose if fiddler crabs return to a single group in the subfamily Ucinae.


Supertribe Ucitae Dana, 1851

Type
Genus Uca
Part of subfamily
Subfamily Ucinae
Contains tribe
Tribe Ucini

The supertribe Ucitae contains only a single tribe. Under current nomenclature it is redundant/identical in content with the subfamily Ucinae, but could serve an important nomenclatural purpose if Ucinae is expanded to include all fiddler crabs.

Tribes

Under the pair of subfamilies and/or supertribes, fiddler crabs can be split into three tribes. These tribes are likely to be stable even if the number of subfamilies changes.


Tribe Gelasimini Miers, 1886

Type
Genus Gelasimus
Part of supertribe
Supertribe Gelasimitae
Contains genera
Genus Austruca, Genus Cranuca, Genus Gelasimus, Genus Paraleptuca, Genus Tubuca, Genus Xeruca

The Gelasimini contains all of the fiddler crab genera found along the coasts and islands of the Indian Ocean and the central and western Pacific Ocean.


Tribe Minucini Bott, 1973

Type
Genus Minuca
Part of supertribe
Supertribe Gelasimitae
Contains genera
Genus Leptuca, Genus Minuca, Genus Petruca

The Minucini contains the broad-front fiddler genera found along the coasts of the Americas.


Tribe Ucini Dana, 1851

Type
Genus Uca
Part of supertribe
Supertribe Ucitae
Contains genera
Genus Afruca, Genus Uca

The Ucini contains the narrow-front fiddler genera found along the American coasts and the single genus found on the eastern Atlantic Ocean. It is redundant/identical with the supertribe Ucitae, but included for rank symmetry.

Genera

Until recently, fiddler crabs were generally considered to belong to a single genus, Gelasimus for most of the 19th century, Uca for the 20th and early 21st. Shih et al. (2016) divided fiddler crabs into eleven genera, all of which had previously been considered subgenera. These genera fall into three main groups represented by the tribes described above.


Genus Afruca Crane, 1975

Type
Afruca tangeri
Part of tribe
Tribe Ucini
Contains species
Afruca miocenica , Afruca tangeri

This monotypic genus consists of the single species Afruca tangeri. It is the only species found in the eastern Atlantic Ocean, along the western coast of Africa and the southeastern edge of Europe.


Genus Austruca Bott, 1973

Type
Austruca lactea
Part of tribe
Tribe Gelasimini
Contains subgenera
Subgenus Austruca, Subgenus Cuneatuca, Subgenus Sinduca

This genus is the largest broad-front fiddler genus for species from the Indian and central-to-western Pacific Oceans.


Genus Cranuca Beinlich & von Hagen, 2006

Type
Cranuca inversa
Part of tribe
Tribe Gelasimini
Contains species
Cranuca inversa

This monotypic genus consists of the single species Cranuca inversa.


Genus Gelasimus Latreille, 1817

Type
Gelasimus vocans
Part of tribe
Tribe Gelasimini
Contains subgenera
Subgenus Gelasimus, Subgenus Mesuca

Gelasimus was considered to be the primary fiddler crab genus for most of the 19th century, until it was shown that Uca had priority (Rathbun 1893). Starting toward the end of the 20th century it was used as a subgenus of Uca. It returned to genus status when fiddler crabs were separated into multiple genera (Shih et al. 2016).


Genus Leptuca Bott, 1973

Type
Leptuca stenodactylus
Part of tribe
Tribe Minucini
Contains species
Leptuca batuenta, Leptuca beebei, Leptuca coloradensis, Leptuca crenulata, Leptuca cumulanta, Leptuca deichmanni, Leptuca dorotheae, Leptuca festae, Leptuca helleri, Leptuca inaequalis, Leptuca latimanus, Leptuca leptodactyla, Leptuca limicola, Leptuca musica, Leptuca oerstedi, Leptuca panacea, Leptuca pugilator, Leptuca pygmaea, Leptuca saltitanta, Leptuca speciosa, Leptuca spinicarpa, Leptuca stenodactylus, Leptuca subcylindrica, Leptuca tallanica, Leptuca tenuipedis, Leptuca terpsichores, Leptuca thayeri, Leptuca tomentosa, Leptuca umbratila, Leptuca uruguayensis

The genus Leptuca represents one of the two broad-front American genera which make up the tribe Minucini. The relationships between these genera has been a little unclear as a number of species have been moved back and forth between them as our systematic understanding of the groups has been refined.


Genus Minuca Bott, 1954

Type
Minuca mordax
Part of tribe
Tribe Minucini
Contains species
Minuca argillicola, Minuca brevifrons, Minuca burgersi, Minuca ecuadoriensis, Minuca galapagensis, Minuca hamlini , Minuca herradurensis, Minuca longisignalis, Minuca marguerita, Minuca minax, Minuca mordax, Minuca osa, Minuca panema, Minuca pugnax, Minuca rapax, Minuca victoriana, Minuca virens, Minuca vocator, Minuca zacae

The genus Minuca was originally erected as a subgenus to represent the broad-front fiddlers (as a contrast to the narrow-front species). It now represents one of the two broad-front American genera which make up the tribe Minucini. The relationships between these genera has been a little unclear as a number of species have been moved back and forth between them as our systematic understanding of the groups has been refined.


Genus Paraleptuca Bott, 1973

Type
Paraleptuca chlorophthalmus
Part of tribe
Tribe Gelasimini
Contains species
Paraleptuca boninensis, Paraleptuca chlorophthalmus, Paraleptuca crassipes, Paraleptuca splendida

This small genus contains a few closely-related species with medium-to-broad fronts.


Genus Petruca Shih et al., 2015

Type
Petruca panamensis
Part of tribe
Tribe Minucini
Contains species
Petruca panamensis

This monotypic genus consists of the single species Petruca panamensis.


Genus Tubuca Bott, 1973

Type
Tubuca urvillei
Part of tribe
Tribe Gelasimini
Contains subgenera
Subgenus Angustuca, Subgenus Australuca, Subgenus Tubuca

This large genus contains most of the narrow-front fiddler species found in the Indian and central-to-western Pacific Oceans.


Genus Uca Leach, 1814

Type
Uca major
Part of tribe
Tribe Ucini
Contains subgenera
Subgenus Acanthoplax, Subgenus Uca

The genus Uca has a complicated history. 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, fiddler crabs were considered to be in the genus 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) at the time. 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.

Uca persisted as the sole genus of fiddler crabs until Shih et al. (2016) elevated eleven subgenera into separate genera. The genus Uca now represents the large, narrow-front fiddlers found in the Americas.


Genus Xeruca Shih, 2015

Type
Xeruca formosensis
Part of tribe
Tribe Gelasimini
Contains species
Xeruca formosensis

This monotypic genus consists of the single species Xeruca formosensis.

Subgenera

Prior to Shih et al. (2016), all fiddler crabs were considered to be a single genus and thus they were divided into subgenera within that genus. With the raising of the old subgenera to new genera, most of the new genera do not currently have subgenera. However, a few of the new genera have distinct enough subgroupings of species to warrant subgenera of their own.


Subgenus Acanthoplax H. Milne Edwards, 1852

Type
Uca insignis
Part of genus
Genus Uca
Contains species
Uca antiqua , Uca insignis, Uca maracoani, Uca marinae , Uca ornata

This subgenus within the genus Uca contains a number of very large species whose major claws have strikingly large and flat pollex and dactyl.


Subgenus Angustuca Rosenberg, 2019

Type
Tubuca acuta
Part of genus
Genus Tubuca
Contains species
Tubuca acuta, Tubuca rhizophorae, Tubuca rosea

This subgenus of Tubuca contains three closely-related species that Crane (1975) had considered a superspecies complex under the name acuta.


Subgenus Australuca Crane, 1975

Type
Tubuca bellator
Part of genus
Genus Tubuca
Contains species
Tubuca bellator, Tubuca elegans, Tubuca hirsutimanus, Tubuca longidigitum, Tubuca polita, Tubuca seismella, Tubuca signata

Australuca was originally a subgenus of Uca. It was eventually abandoned when found to be a subset of another subgenus, btu with the Tubuca now considered a genus in its own right, Australuca can serve as a subgenus within it. All but one of the narrow-front fiddler species in this genus are restricted to Australia.


Subgenus Austruca Bott, 1973

Type
Austruca lactea
Part of genus
Genus Austruca
Contains species
Austruca albimana, Austruca annulipes, Austruca citrus, Austruca cryptica, Austruca iranica, Austruca lactea, Austruca mjoebergi, Austruca occidentalis, Austruca perplexa

The subgenus Austruca, within the genus Austruca, contains the species often unofficially referred to as the lactea-species group. It is the four species identified by Crane (1975) as subspecies of Austruca lactea, along with additional species subsequently split from that group.


Subgenus Cuneatuca Rosenberg, 2019

Type
Austruca triangularis
Part of genus
Genus Austruca
Contains species
Austruca bengali, Austruca triangularis, Austruca variegata

The subgenus Cuneatuca, within the genus Austruca, contains the two very small, closely-related species that Crane (1975) had combined into the single species Uca triangualris.


Subgenus Gelasimus Latreille, 1817

Type
Gelasimus vocans
Part of genus
Genus Gelasimus
Contains species
Gelasimus borealis, Gelasimus dampieri, Gelasimus excisa, Gelasimus hesperiae, Gelasimus jocelynae, Gelasimus vocans, Gelasimus vomeris

The subgenus Gelasimus, within the genus Gelasimus, contains the species often unofficially referred to as the vocans-species group. It is the six species identified by Crane (1975) as subspecies of Gelasimus vocans, along with an additional species subsequently split from that group.


Subgenus Mesuca Bott, 1973

Type
Gelasimus tetragonon
Part of genus
Genus Gelasimus
Contains species
Gelasimus tetragonon

This monotypic subgenus within the genus Gelasimuscontains the species Gelasimus tetragonon.


Subgenus Sinduca Rosenberg, 2019

Type
Austruca sindensis
Part of genus
Genus Austruca
Contains species
Austruca sindensis

This monotypic subgenus within the genus Austruca contains the species Austruca sindensis.


Subgenus Tubuca Bott, 1973

Type
Tubuca urvillei
Part of genus
Genus Tubuca
Contains species
Tubuca alcocki, Tubuca arcuata, Tubuca capricornis, Tubuca coarctata, Tubuca demani, Tubuca dussumieri, Tubuca flammula, Tubuca forcipata, Tubuca paradussumieri, Tubuca typhoni, Tubuca urvillei

This subgenus contains most of the species that had long been considered part of the genus when it was still a subgenus of Uca.


Subgenus Uca Leach, 1814

Type
Uca major
Part of genus
Genus Uca
Contains species
Uca heteropleura, Uca intermedia, Uca major, Uca monilifera, Uca oldroydi , Uca princeps, Uca stylifera

This subgenus is a bit of a catch-all for the species in the genus that are not part of the subgenus Acanthoplax.