Callichirus major sensu lato is a monophyletic species complex of ghost shrimp in the infraorder Axiidea, found in flat sandy beaches across the Pan-American coastline.
Originally described as a single species, genetic studies eventually classified it as at least four almost morphologically indistinguishable species, one of which was given the binomial denomination Callichirus macrotelsonis (Peiró, 2012). The complex is distinguished by sexual dimorphism, distinctly separated coxae and bases in the maxilla and gonochorism, despite vestigial signs of ancestral hermaphroditism in C. macrotelsonis.
The widespread extraction of individuals for living fishing bait has endangered both its conservation and that of their respective ecosystems.
Callichirus major was first described as Callianassa major by Thomas Say in 1818, specifically in the Gulf of Mexico and East Florida.[1] Its genus was renamed Callichirus in 1866 by William Stimpson.[2] It used to be classified in the infraorder Thalassinidea (ghost shrimp) of decapod crustaceans until this infraorder was proven to be paraphyletic in 2009, after which the family Callianassidae, in which C. major is included, was definitely placed in the infraorder Axiidae (de Saint Laurent, 1979).[3] A supposed Brazilian species described as Anomalocaris macrotelsonis (Ortmann, 1893) was eventually discovered in 1974 to be the fourth larval stage of C. major.[4]
In 1995, the results of genetic testing published by Staton and Felder concluded that Caribbean Colombian populations described as C. major could not belong to the same species as those found in the United States Atlantic Ocean. Among those in the United States, although there were minor morphological differences between the populations of the East Coast (from North Carolina to Georgia) and those of the Gulf of Mexico (from Louisiana to Texas), the overall internal diversity of each population made them genetically indistinguishable.[5] Samples of Pacific Mexican ghost shrimps also later suggested a species not identical, but close to C. major s.s.[6]
Further testing by Peiró confirmed that populations of the East Coast and the Gulf of Mexico belonged to the same species, which was in turn different from the Colombian ones, but C. major was definitely described not as only two, but four distinct species with a monophyletic origin. Apart from C. major stricto sensu in the United States, the Colombian populations were found to belong to a different species than those of Pacific Mexico and Costa Rica. Those were described simply as C. aff. major sp. 2 and C. aff. major sp. 1, still pending binomial naming. The Brazilian populations, on the other hand, were successfully described as a fourth one, designed as C. macrotelsonis.[7] The relative genetical proximity between Caribbean and Pacific populations implies a separation posterior to the uplift of the Isthmus of Panama.[8] Rio confirmed Peiró's tests at a morphological level, suggesting that the absolute lack of information on vestigial signs of hermaphroditism in C. major s.s. might indicate that this feature could be exclusive of the Brazilian species, which she denominated C. brasiliensis sp. nov.[9]
Based on descriptions by Sakai and Türkay in 2012, Felder and Dworschak suggested that the formers' denomination C. santarosaensis might be ascribed to populations formerly designated as C. major in the northern Gulf of Mexico, although pending further genetic analysis and casting doubt on the validity of Sakai's and Türkay's description of a damaged juvenile specimen, prejudicing the validity of the taxon.[10][11]
The great morphological similarities between all species of the C. major complex has proven to be a difficulty for the distinction of its closely related species.[12]
The C. major has a carapace with a rigid anterior margin, turning backwards to the linea thalassinica (an uncalcified membranous groove, in the complex's case distinctly parallel to the longitudinal axis of the body) and forwards to the rounded angles of the branchiostegal lung. The sternum is inconspicuous between the first and third pairs of pereopods. The complex has a flanked rostrum, with characteristically obtuse angles near the base of the eyestalks, which in turn almost reach the basal segment of the antennules' peduncles. The antennules have a third segments 1.5 to 2.5 times as longer as the first and second together.[13]
The maxilla has distinctly separated coxae and bases. The first pair of pereopods is very unequal in size, especially in adult males, presenting a uniquely bold instance sexual dimorphism in the genus. The second pair is well chelated, but the fourth and fifth have rather imperfect chelae. The first and second segments of the abdomen are membranous and soft, the latter being longer than the first, and almost twice as long as the third, fourth and sixth segments. The third, fourth and sixth segments have approximately the same length, although the fifth is slightly longer than its adjacent segments.[14]
Distinctly for its genus, C. major is gonochoristic. The vestigial signs of ancestral hermaphroditism (namely, the production of unused ovaries by males and additional gonopores in females) in C. macrotelsonis and the fully functional hermaphroditism in sister species such as C. seillacheri, however, implies that the genus Callichirus may have a unique case of crustacean basal, but not universal, hermaphroditism.[15]
C. major s.l. occurs in open, dissipative and flat sandy beaches, mostly in deep galleries in the intertidal zone, but also in shallow subtidal depths of 2–3 m.[1] It has a very large geographic distribution across Pan-American coastlines. In the Atlantic coastline, the distribution occurs from North Carolina to Santa Catarina, although with a large hiatus from Southern Texas to Pará, being therein only sporadically found in Colombia and Venezuela.[1][16] In the Pacific coastline, the complex has been identified in both Baja California and Costa Rica.[8][16]
C. major s.l. is widely employed as living fishing bait by many human coastal populations, including those in the United States and Brazil, due to its easy availability.[17] Ghost shrimp mass extraction, both specifically regarding C. major and generically, has been described as ecologically harmful not only for their own ecological stability, but also to different animals that are killed in the procedure.[18] The complex's IUCN status has been suggested as critically endangered, although it has not been officially reviewed by the IUCN.[19]
Callichirus major sensu lato is a monophyletic species complex of ghost shrimp in the infraorder Axiidea, found in flat sandy beaches across the Pan-American coastline.
Originally described as a single species, genetic studies eventually classified it as at least four almost morphologically indistinguishable species, one of which was given the binomial denomination Callichirus macrotelsonis (Peiró, 2012). The complex is distinguished by sexual dimorphism, distinctly separated coxae and bases in the maxilla and gonochorism, despite vestigial signs of ancestral hermaphroditism in C. macrotelsonis.
The widespread extraction of individuals for living fishing bait has endangered both its conservation and that of their respective ecosystems.
Callichirus major is een tienpotigensoort uit de familie van de Callianassidae.[1] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1818 door Thomas Say.
Bronnen, noten en/of referenties
Corrupto (Callichirus major, Stimpson, 1866) é um crustáceo decápode cavador, lato sensu podendo referir-se a todos os crustáceos da antiga infraordem Thalassinidea,[1] hoje superada pela Axiidea (à qual pertence o Callichirus major) e a Gebiidea.[2][3]
Os corruptos apresentam indivíduos maiores atingindo cerca de 20 centímetros de comprimento, tendo o abdome com coloração amarelada. Possuem garras em forma de pinças, sendo uma delas bem maior que a outra. Deve-se tomar cuidado com os espécimes de maior tamanho, já que sua garra pode causar pequenos ferimentos. São apelidados de corruptos, pois são muitos, não "aparecem" e são difíceis de capturar. Eles cavam buracos onde se escondem, e são capturados com o equipamento que faz furos para guarda-sol.
Vivem em praias rasas de areia fina, próximos à linha d'água, em profundas tocas verticais escavadas na areia. Quanto maior o buraco, maior o animal que nele habita. Alimentam-se de matéria orgânica em decomposição e de pequenos animais. Geralmente seus buracos ficam expostos apenas durante a maré baixa, 20 centímetros ou mais. Portanto, conforme a tábua das marés, verifique o dia mais adequado, num horário em que a água esteja em seu ponto mínimo. Nos buracos cobertos pela água, o Corrupto estará mais próximo à superfície.
A pesca destes organismos cavadores pode ocasionar alterações, tanto na espécie alvo, como em outras espécies existentes no sedimento, devido à própria técnica de captura utilizada. Na África do Sul, a cada 50 corruptos coletados com bomba de sucção, 50 gramas de organismos da macroinfauna acabam morrendo ou sendo predados por aves e outros organismos, em consequência da perturbação. Por outro lado, um esforço de pesca excessivo pode levar a sobre-exploração do recurso e até ao total desaparecimento das populações alvo. A estrutura populacional de Callichirus major pode ter sido afetada pela pesca no litoral do Estado de São Paulo, onde foi registrada uma diminuição na moda média do tamanho dos indivíduos da população ao longo de 6 anos de estudo. Este resultado pode ser consequência de um aumento na intensidade dos recrutamentos, devido à maior disponibilidade de substrato resultante da remoção de indivíduos maiores.[4]
No município de Ilha Comprida, moradores locais fazem um trabalho de conscientização junto aos pescadores amadores que buscam a exploração deste categoria de isca. A devolução das fêmeas ovuladas para garantia de reprodução e sobrevivência da espécie, são um dos principais argumentos para tal.
C. major s.l. ocorre em praias arenosas abertas, dissipativas e planas, principalmente em galerias profundas na zona entremarés, mas também em profundidade subdiais rasas de 2–3 m.[5] Tem uma distribuição geográfica muito grande ao longo da costa pan-americana. Na costa atlântica, a distribuição ocorre da Carolina do Norte a Santa Catarina, embora com um grande hiato do sul do Texas ao Pará, sendo encontrada apenas esporadicamente na Colômbia e na Venezuela.[5][6] Na costa do Pacífico, o complexo foi identificado na Baja Califórnia e na Costa Rica.[7][6]
C. major s.l. é amplamente empregada como isca viva de pesca por muitas populações costeiras humanas, incluindo as dos Estados Unidos e do Brasil, devido à sua fácil disponibilidade.[8] A extração em massa do camarão fantasma, tanto especificamente em relação a C. major quanto genericamente, foi descrita como ecologicamente prejudicial não apenas para sua própria estabilidade ecológica, mas também para diferentes animais que são mortos no procedimento.[9] O status da IUCN do complexo foi sugerido como criticamente em perigo, embora não tenha sido oficialmente revisado pela IUCN.[10]
Corrupto (Callichirus major, Stimpson, 1866) é um crustáceo decápode cavador, lato sensu podendo referir-se a todos os crustáceos da antiga infraordem Thalassinidea, hoje superada pela Axiidea (à qual pertence o Callichirus major) e a Gebiidea.
