Platychirograpsus spectabilis

Invasion History

First Non-native North American Tidal Record: 1939
First Non-native West Coast Tidal Record:
First Non-native East/Gulf Coast Tidal Record: 1939

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General Invasion History:

The Saber Crab, Platychirograpsus spectabilis, is a grapsoid crab native to rivers in the states of Veracruz and Tabasco in southeastern Mexico. It is catadromous – mating adults and ovigerous females have been seen in brackish lagoons in Mexico, but adults are commonly found in and along rivers and burrowing in riverbanks more than 200 km from the sea (Marchand et al. 1946; Poss et al. 1999; Schubart et al. 2002).

North American Invasion History:

Invasion History on the Gulf Coast:

In 1939, Lewis Marchand found large numbers of this crab among rocks and submerged timbers in the Hillsborough River, Florida, a Tampa Bay tributary. The crabs occurred up to 10 miles upstream from the bay. A sawmill on the river received cedar logs shipped from Mexico before World War II, and these crabs were commonly found on the logs. In 1940, Marchand observed P. spectabilis on logs in the hold of a ship in the Port of Tampa, which had arrived from Tabasco, Mexico (Marchand 1946). In the 1980s-1990s, these crabs were seen in the Alafia River, Florida, but an acid spill in 1998 may have affected their population. The distribution of these crabs in Florida is quite restricted, and their current status is uncertain (Poss 1999; Baker et al. 2004). Transport on log cargo may be the main introduction vector for this species, but the transport of larvae in ballast water is also possible.

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Description

Platychirograpsus spectabilis, the Saber Crab, has a roughly square carapace. The frontal region, between the eyes has two blunt teeth, with a gap at the midpoint. Posterior to the eyes, there are four teeth on the antero-lateral edge of the carapace. The posterior edge is straight. The carapace is rough, with two median bulges, separated by a sinus (groove). The edges of the walking legs are lined with triangular spines. A remarkable feature of mature males is a hugely enlarged single claw, which can exceed the width and length of the carapace. Either the right or the left claw (but never both) become enlarged. The claw is flattened laterally, and the palm of the claw is roughly triangular, the fingers are thick and blunt and the modified claw resembles a wrench. The surface of the claw is covered with large tubercles. Claws of females, juvenile males, and the unmodified claw of mature males are small, less than one-half the carapace width. The proximal inner surface of each finger of the claw bears six or seven large tubercles, while the outer third is a prominent hardened ridge, apparently modified for scraping algae off surfaces. Male crabs reach 51 mm carapace width, females 41 mm (Rathbun 1914; Marchand 1946; Burmeister 1978; Schubart et al. 2002). Note: Some of this description is based on photographs in Marchand 1946 and Burmeister 1978.

The taxonomist who first described P. spectabilis, de Man, erroneously gave the type locality as Gabon, West Africa. It was subsequently redescribed as P. typicus, from Mexico (Rathbun 1914). However, the type specimens proved to be identical to the Mexican specimens, and no specimens of this genus are known from Africa, so P. spectabilis is considered the senior and correct name (Schubart et al. 2002).

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Taxonomy

Ecology

General:

Life History- Platychirograpsus spectabilis is catadromous – adults live in and along freshwater rivers and streams, but migrate to brackish estuaries for spawning (Schubart et al. 2000; Schubart et al. 2002). Male brachyuran crabs copulate with females, inserting the first pair of pleopods, carrying sperm, into the female's seminal receptacles. The eggs are fertilized internally, and then extruded as a 'sponge' or a mass of eggs, which is brooded between the abdomen and the body (Barnes 1983). The eggs hatch into zoeae, larvae about 0.7 mm long, armed with long spines, which drift in the plankton. Each zoea goes through an unknown number of molts, and eventually molts into a postlarval megalopa, with prominent eyes and partially developed appendages (Kornienko et al. 2008). The megalopa molts into a miniature 'first crab' which has all the features of an adult crab, and is capable of crawling on the benthos (Barnes 1983). The juvenile stages of P. spectabilis apparently migrate upstream into non-tidal freshwaters (Schubart et al. 2000; Schubart et al. 2002). The large modified claws of mature males may be used for aggressive displays or fighting between males (Marchand 1946).

Food:

Macroalgae, Diatoms, dead fish

Trophic Status:

Omnivore

Omni

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Habitats

General Habitat	Nontidal Freshwater	None
General Habitat	Fresh (nontidal) Marsh	None
General Habitat	Tidal Fresh Marsh	None
General Habitat	Swamp	None
General Habitat	Unstructured Bottom	None
General Habitat	Coarse Woody Debris	None
Salinity Range	Limnetic	0-0.5 PSU
Salinity Range	Oligohaline	0.5-5 PSU
Tidal Range	Subtidal	None
Tidal Range	Low Intertidal	None
Tidal Range	Mid Intertidal	None
Tidal Range	High Intertidal	None
Tidal Range	Supratidal	None
Vertical Habitat	Endobenthic	None

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Tolerances and Life History Parameters

Minimum Salinity (‰)	0	None
Maximum Length (mm)	44.5	Adult males, females up to 34.8 mm (Schubart et al. 2002)
Broad Temperature Range	None	Subtropical
Broad Salinity Range	None	Nontidal Limnetic-Polyhaline

General Impacts

In the 1930s, Platychirograpsus spectabilis were abundant in their restricted range in Hillsborough River, but no ecological or economic impacts were reported (Marchand 1946). At present, they are apparently rare - we have no recent information on their abundance in Florida.

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References

Baker, Patrick; Baker, Shirley M.; Fajans, Jon (2004) Nonindigenous marine species in the greater Tampa Bay ecosystem., Tampa Bay Estuary Program, Tampa FL. Pp. <missing location>

Barnes, Robert D. (1983) Invertebrate Zoology, Saunders, Philadelphia. Pp. 883

Burmeister, E. G. (1978) Zum fund von Platychirograpsus typicus Rathbun 1914 (Crustacea, Decapoda, Brachyura) in Mexico, Studies on Neotropical Fauna and Environment 13(3): 195-201

Kornienko, E. S.; Korn, O. M.; Kashenko, S. D. (2008) Comparative morphology of larvae of coastal crabs (Crustacea: Decapoda: Varunidae), Russian Journal of Marine Biology 34(2): 77-93

Marchand, Lewis J. (1946) The saber crab, Platychirograpsus typicus Rathburn, in Florida: a case of accidental dispersal, Quarterly Journal of the Florida Academy of Sciences 9(2): 93-100

McCann, James A.; Arkin, Lori; Williams, James D. (1996) <missing title>, University of Florida, Center for Aquatic Plants, Gainesville. Pp. unpaged

Montalvo-Urgel, Hugo; Sánchez, Alberto J.; Florido, Rosa; Macossay-Cortez, Alberto A. (2010) [List of crustaceans distributed in submerged woody debris in the tropical wetlands of Pantanos de Centla, southern Gulf of Mexico], Revista Mexicana de Biodiversidad 81: S121- S131

Poss, Stuart G. 1999 Nonindigenous species in the Gulf of Mexico. <missing URL>



Rathbun, Mary J. (1914) New genera and species of American brachyrhynchous crabs, Proceedings of the United States National Museum 47: 117-129

Schubart, Christoph D.; Cuesta, José A.; Felder, Darryl L. (2002) Glyptograpsidae, a new brachyuran family from Central America: Larval and adult morphology, and a molecular phylogeny of the Grapsoidea., Journal of Crustacean Biology 22: 28-44

Schubart, Christoph D.; Cuesta, Jose´ A.; Diesel, Rudolf; Felder, Darryl L. (2000) Molecular phylogeny, taxonomy, and evolution of nonmarine lineages within the american grapsoid crabs (Crustacea: Brachyura), Molecular Phylogenetics and Evolution 15(2): 179-190

U.S. National Museum of Natural History 2002-2021 Invertebrate Zoology Collections Database. http://collections.nmnh.si.edu/search/iz/

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