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Wikisource:WikiProject Open Access/Programmatic import from PubMed Central/The land crab Johngarthia planata (Stimpson 1860) (Crustacea Brachyura Gecarcinidae) colonizes human-dominated ecosystems in the continental main

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The land crab Johngarthiaplanata (Stimpson, 1860) (Crustacea, Brachyura, Gecarcinidae) colonizes human-dominated ecosystems in the continental mainland coast of Mexico by Mr Robert Perger
Biodiversity Data Journal , iss. p.

AbstractEdit

AbstractThe land crab Johngarthiaplanata (Stimpson, 1860) has been reported from the Baja California Peninsula and several oceanic islands in the Eastern Pacific as well as inshore islands of the Mexican, Costa Rican and Colombian coast. However, the species has not been observed on the continental mainland, as it is likely that the high diversity of terrestrial predators/competitors make the establishment of mainland populations nearly impossible. In this contribution, several new records of this species that have been observed in urban areas along the continental Pacific coast of Mexico are reported. These records demonstrate that the presence of humans does not necessarily have a negative impact on land crab species. Indeed, the presence of humans may actually discourage the presence of native crab predators/competitors and hence increase the likelihood of a successful mainland settlement of land crab species that are otherwise island and peninsula restricted. The presence of Johngarthiaplanata is ecologically relevant for coastal forests because gecarcinid crabs significantly influence plant recruitment and Johngarthiaplanata is considerably larger than the mainland species Gecarcinusquadratus.

IntroductionEdit

Macroevolutionary transitions between marine and non-marine habitats are uncommon and rarely lead to long-term success in the invaded habitat ([1]). This is largely due to terrestrial niches being occupied by groups with a longer evolutionary history in these habitats as well as the marine invaders' lack of traits withwhich to successfully confront the differences in terrestrial selection regimes ([1]).

However, while their larvae still develop in marine habitats, adults of the crab family Gecarcinidae have successfully conquered island habitats, where they play an important ecological role ([2] for a review). Species of the Gecarcinus-group (including Johngarthia, Gecarcinus and Gecarcoidea ([3]) are dominant through sheer numbers, on some islands their mass exceeds the total mass of animals reported in tropical rain forests in Costa Rica and the central Amazon ([2]) and they may occupy the top of the energy pyramid ([4]).

Nevertheless, despite their success on islands and possible dispersal in their larval stage via sea currents, most species of the Gecarcinus-group are absent from continental mainland habitats ([3]; see [5]). One reason for this may be the predictable mass migrations to the coast for larval release (e.g. [6], [7], [8]), which may render species of this group especially vulnerable to terrestrial predators, therefore limiting dispersion and the chances of success on the continental mainland. The negative impact on populations exerted by e.g. terrestrial vertebrates is supported by observed population declines or extinctions after island settlements by humans, which often actively hunt land crabs, or after the anthropogenic introduction of crab predators/competitors such as rats, feral cats and pigs ([5]).

Johngarthiaplanata (Stimpson, 1860) appears to be a textbook example for the group's failure to establish itself on the continental mainland despite the advantages of ecological flexibility and favorable larval dispersion patterns (reviewed by [9]). Johngarthiaplanata occurs on the Baja California Peninsula and several oceanic islands in the Eastern Pacific as well as on inshore islands of the Mexican, Costa Rican and Colombian coasts. This wide presence is likely the result of amplified dispersal via coastal currents ([9]). However, likely due to the large diversity of terrestrial predators/competitors, Johngarthiaplanata has not been observed on continental mainland locations until now ([9]).

In this study I report the first continental mainland records for Johngarthiaplanata and discuss the possibility that human presence might actually facilitate the mainland settlement of such a species.

Materials and methodsEdit

The present study encompasses the Pacific coast from Mexico to Colombia. Following [10] and [11] the Baja California peninsula is treated separately to the rest of Mexico, which is referred to throughout the text as “Mexican mainland” or “continental mainland” respectively. To investigate the mainland presence/absence patterns of Johngarthiaplanata I performed an Internet search via Google.com (search function “images”) and flickr.com. Flickr is an image hosting web site that is reported to host more than 6 billion photographs. Users uploading their photos to Flickr are able to add key words (“tags”) that facilitate a search on Flickr and also in web search services such as Google and Yahoo.  I searched with various combinations of the key words “crab” or “cangrejo” (Spanish for crab) and “Pacific, Mexico, Guatemala, El Salvador, Nicaragua, Costa Rica, Panama, Colombia”; and all regions of the respective countries with access to the Pacific coast. I then considered for evaluation only individuals on photographs from locations that were confirmed by the photographers and demonstrated clearly visible characteristics of Johngarthiaplanata (see [9]).

The following abbreviations are used in the text: LACM – Natural History Museum of Los Angeles County, Los Angeles, California; MNHN – Muséum National d’Histoire Naturelle, Paris, France; MZ-UCR – Museo de Zoología, Universidad de Costa Rica, San José, Costa Rica; USNM – National Museum of Natural History, Smithsonian Institution, Washington, D.C.

Taxon treatmentsEdit

JohngarthiaplanataEdit

(Stimpson, 1860)

MaterialsEdit

  1. Type status:Other material. Occurrence: recordedBy: Robert Perger; individualCount: 2; sex: 1 male, 1 female; reproductiveCondition: egg-bearing female; behavior: running, agonistic display, pinching, producing bubbles in mouth area; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; island: Caño Island; country: Costa Rica; stateProvince: Puntarenas; verbatimLocality: Caño Island; verbatimElevation: 39 m; decimalLatitude: 8.70861111111111; decimalLongitude: -83.88916666666667; Identification: identificationID: Robert Perger; Event: samplingProtocol: manual search; samplingEffort: 2 hours; eventDate: 2011-02-25# Type status:Other material. Occurrence: recordedBy: Robert Perger; individualCount: 14; sex: juveniles; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; island: Nairita Island; country: Costa Rica; stateProvince: Puntarenas; verbatimLocality: Nairita Island; verbatimElevation: 1 m; decimalLatitude: 8.67; decimalLongitude: -83.71777777777778; Identification: identificationID: Robert Perger; Event: samplingProtocol: manual search; samplingEffort: 4 hours; eventDate: 2011-03-17; Record Level: institutionCode: MZ-UCR# Type status:Other material. Occurrence: recordedBy: F. Joyce; individualCount: 2; sex: males; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; island: Colorada Island; country: Costa Rica; stateProvince: Guanacaste; verbatimLocality: Colorada Island; verbatimElevation: 13 m; decimalLatitude: 10.846111111111112; decimalLongitude: -85.8611111111111; Identification: identificationID: Robert Perger; Event: eventDate: 2000-10-20; Record Level: institutionCode: MZ-UCR# Type status:Other material. Occurrence: recordedBy: A. Anthony; individualCount: 1; sex: male; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; island: Socorro Island; country: Mexico; verbatimLocality: Socorro Island; Record Level: institutionCode: MNHN# Type status:Other material. Occurrence: individualCount: 2; sex: males; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; island: Socorro Island; country: Mexico; verbatimLocality: Socorro Island; Identification: identificationID: John Garth; Event: eventDate: 1971-02-16; Record Level: institutionCode: LACM# Type status:Other material. Occurrence: recordedBy: A. Anthony; individualCount: 1; sex: male; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; island: Socorro Island; country: Mexico; verbatimLocality: Socorro Island; Record Level: institutionCode: USNM# Type status:Other material. Occurrence: individualCount: 2; sex: males; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; island: San Benedicto Island; country: Mexico; verbatimLocality: San Benedicto Island; Identification: identificationID: John Garth; Record Level: institutionCode: LACM# Type status:Other material. Occurrence: recordedBy: A. Anthony; individualCount: 1; sex: male; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; island: San Benedicto Island; country: Mexico; verbatimLocality: San Benedicto Island; Record Level: institutionCode: USNM# Type status:Other material. Occurrence: recordedBy: Léon Diguet; individualCount: 1; sex: male; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Mexico; verbatimLocality: Baja California; Record Level: institutionCode: MNHN# Type status:Other material. Occurrence: recordedBy: Edward William Nelson; Edward Alphonso Goldman; individualCount: 1; sex: male; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Mexico; verbatimLocality: María Cleofas Island; Event: eventDate: 1897-05-30; Record Level: institutionCode: USNM# Type status:Other material. Occurrence: recordedBy: Conrad Limbaugh; individualCount: 4; sex: males; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: France; verbatimLocality: Clipperton Island; Identification: identificationID: John Garth; Event: eventDate: 1958-09-12; Record Level: institutionCode: LACM# Type status:Other material. Occurrence: individualCount: 1; sex: male; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: France; verbatimLocality: Clipperton Island; Identification: identificationID: Danièle Guinot; Record Level: institutionCode: MNHN# Type status:Other material. Occurrence: recordedBy: J. Arnheim; individualCount: 2; sex: 1 male, 1 female; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: France; verbatimLocality: Clipperton Island; Record Level: institutionCode: USNM# Type status:Other material. Occurrence: recordedBy: María Elena Valencia; individualCount: 1; sex: female; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Panama; verbatimLocality: Iguana Island; Identification: identificationID: Robert Perger; Event: year: 2006; habitat: beach; Record Level: type: Photograph; rightsHolder: María Elena Valencia# Type status:Other material. Occurrence: recordedBy: Julio Larish; individualCount: 1; sex: juvenile; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Panama; verbatimLocality: Iguana Island; Identification: identificationID: Robert Perger; Event: year: 2013; habitat: beach; Record Level: type: Photograph; rightsHolder: Julio Larish# Type status:Other material. Occurrence: recordedBy: Lisa Brettschneider; individualCount: 1; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Mexico; stateProvince: Sinaloa; verbatimLocality: Mazatlán; Identification: identificationID: Robert Perger; Event: year: 2008; habitat: beach; Record Level: type: Photograph; rightsHolder: Lisa Brettschneider# Type status:Other material. Occurrence: recordedBy: Lisa Johnston; individualCount: 1; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Mexico; stateProvince: Nayarit; verbatimLocality: Sayulita; Identification: identificationID: Robert Perger; Event: year: 2005; habitat: beach; Record Level: type: Photograph; rightsHolder: Lisa Johnston# Type status:Other material. Occurrence: recordedBy: Tania Beagley-Brown; individualCount: 1; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Mexico; stateProvince: Nayarit; verbatimLocality: Sayulita; Identification: identificationID: Robert Perger; Event: year: 2007; habitat: on roof of house; Record Level: type: Photograph; rightsHolder: Tania Beagley-Brown# Type status:Other material. Occurrence: recordedBy: Daniel Brewer; individualCount: 2; sex: 1 male, 1 female; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Mexico; stateProvince: Nayarit; verbatimLocality: Sayulita; Identification: identificationID: Robert Perger; Event: year: 2010; habitat: beach; Record Level: type: Photograph; rightsHolder: Daniel Brewer# Type status:Other material. Occurrence: recordedBy: Daniel Brewer; individualCount: 2; sex: 1 male, 1 female; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Mexico; stateProvince: Nayarit; verbatimLocality: Sayulita; Identification: identificationID: Robert Perger; Event: year: 2010; habitat: beach; Record Level: type: Photograph; rightsHolder: Daniel Brewer# Type status:Other material. Occurrence: recordedBy: Madeline Milne; individualCount: 1; sex: male; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Mexico; stateProvince: Nayarit; verbatimLocality: Sayulita; Identification: identificationID: Robert Perger; Event: year: 2013; habitat: beach; Record Level: type: Photograph; rightsHolder: Madeline Milne# Type status:Other material. Occurrence: recordedBy: Darin Williams; individualCount: 1; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Mexico; stateProvince: Jalisco; verbatimLocality: Mismaloya; Identification: identificationID: Robert Perger; Event: year: 2007; habitat: beach; Record Level: type: Photograph; rightsHolder: Darin Williams# Type status:Other material. Occurrence: recordedBy: Derek Zoebelein; individualCount: 1; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Mexico; stateProvince: Colima; verbatimLocality: Manzanillo; Identification: identificationID: Robert Perger; Event: year: 2004; habitat: beach; Record Level: type: Photograph; rightsHolder: Derek Zoebelein# Type status:Other material. Occurrence: recordedBy: Miguel Angel Morales; individualCount: 1; sex: male; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Mexico; stateProvince: Guerrero; verbatimLocality: Ixtapa; Identification: identificationID: Robert Perger; Event: year: 2012; habitat: beach; Record Level: type: Photograph; rightsHolder: Miguel Angel Morales# Type status:Other material. Occurrence: recordedBy: Gustavo A. Zambrano Cabrera; individualCount: 1; sex: male; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Mexico; stateProvince: Oaxaca; verbatimLocality: Mazunte; Identification: identificationID: Robert Perger; Event: year: 2008; habitat: beach; Record Level: type: Photograph; rightsHolder: Gustavo A. Zambrano Cabrera# Type status:Other material. Occurrence: recordedBy: Mike Gardiner; individualCount: 1; sex: male; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Mexico; stateProvince: Oaxaca; verbatimLocality: Escondido Beach; Identification: identificationID: Robert Perger; Event: year: 2010; habitat: beach; Record Level: type: Photograph; rightsHolder: Mike Gardiner# Type status:Other material. Occurrence: recordedBy: Claudia Glechner; individualCount: 1; sex: juvenile; Taxon: scientificName: Johngarthiaplanata Stimpson, 1860; namePublishedIn: Stimpson W (1860) Notes on North American Crustacea, in the museum of the Smithsonian Institution, No II. Annals of the Lyceum of Natural History of New York 7: 176–246.; order: Decapoda; family: Gecarcinidae; genus: Johngarthia; specificEpithet: planata; scientificNameAuthorship: W. Stimpson 1860; Location: waterBody: East Pacific; country: Mexico; stateProvince: Oaxaca; verbatimLocality: Zapotengo Beach; Identification: identificationID: Robert Perger; Event: year: 2011; habitat: beach; Record Level: type: Photograph; rightsHolder: Claudia Glechner

AnalysisEdit

The Internet search revealed photographs of 12 individuals from Mexico (mainland) and three individuals from Panama (Iguana Island) (Table 1, Figs 1, 2). The diagnostic characters used (both apical lobes of the third maxilliped merus subequal, the leg spines prominently developed, the carapace depressed and the dark red color with orange chelipeds and cream cutting edges) (Fig. 1) were consistent with other examined specimens found on islands in Mexico and Costa Rica ([9]) as well as on Gorgona Island, Colombia (see [12]). The specimens found on the Mexican mainland are the first continental mainland specimens ever recorded, and the specimens on Iguana Island are the first recorded in Panama. The species has been previously reported by [13] and [14] for “Panama” in error, likely following the reference “Malpelo Island, off Bay of Panama” by [15]. Malpelo Island is inhabited by Johngarthiamalpilensis, but the island is part of Colombia.

All mainland records of Johngarthiaplanata cited here refer to tourist beaches close to villages or small cities. Several photographs show individuals of Johngarthiaplanata foraging diurnally, running along house walls or even inside of houses and mating (Fig. 1).

The Internet search did not reveal any photographs of Johngarthiaplanata from Guatemala, El Salvador, Nicaragua and Costa Rica. For the latter country, the only known records to date are those cited by [9].

DiscussionEdit

[5] attribute the absence of land crab species on the continental mainland to the presence of predators. However, this pattern is less pronounced in the Neotropics where Cardisomacrassum, Cardisomaguanhumi, Gecarcinuslateralis and Gecarcinusquadratus share evolutionary traits which allow it to adapt to the conditions in a coastal band of the continental mainland (e.g. [16], [17], [2]). On the other hand, the remaining four species of Johngarthia (see [18], [19], [20]) and Gecarcinusruricola ([13]) have been reported from islands only, supporting the pattern suggested by [5]. Several studies strongly indicate that Johngarthiaplanata has not established populations along the Central American mainland coast (see [9] for a short review; Fig. 2), which agrees with the pattern of mainland absence observed in the four congeners. The ecological flexibility of Johngarthiaplanata, which occurs in habitats ranging from island rainforests to rocky terrain with sparse vegetation ([21], [9]), suggest that the most significant factors which preclude such species from inhabiting the mainland are indeed competition or/and predation ([9]). The presence/absence pattern of Johngarthiaplanata in continental mainland habitats roughly coincides with the replacement of the moist forests of Panama and Costa Rica by dry forests that extend from Nicaragua to Mexico (see [22]). The diversity of possible crab predators such as birds ([23]) and mammals ([24]) is lower in the Southern Pacific Dry forest ecoregion than in tropical rainforests of Central America. Whether Johngarthiaplanata appears as well in non-urban areas along the Mexican Pacific coast remains unclear, however, the mainland establishment of such species might be facilitated close to or in urban areas where the lower diversity or/and abundance of possible predators/competitors is influenced by the presence of humans. Studies from undisturbed forest in the Pacific coast of Costa Rica ([17], [25], pers. observ.) relate cryptic behavior of gecarcinid land crabs to less suitable abiotic conditions and predator presence. On Caño and Nairita ([9]), Maria Cleofa ([26]), Socorro ([21]) and Gorgona ([18]) islands, Johngarthiaplanata is active at night, which is most likely due to the presence of bird predators. In contrast, observations from Sayulita ([27]), a newly reported mainland record for Johngarthiaplanata (Table 1; Fig. 1), suggest that the land crab activity there is less influenced by predator impact:

“Visitors who arrive in Sayulita during the rainy season (June-October) and decide to take a leisurely walk through the jungle towards the beach are usually quite surprised, even shocked, to find the jungle floor literally teeming with thousands of purple-and-yellow and red land crabs. Crabs seem to be foraging everywhere in the leaf litter, wildly waving their claws and scurrying away to their burrows and caves at the first apprehension of danger. Most people find them interesting and amusing, even comical, with their tubular, hyper-vigilant eyes, their defensive postures and wild gestures.”

Further photographs and accounts by [27] and Brewer (in litt.) indicate that Johngarthiaplanata is a common element of the urban wildlife and seeks food and shelter in closest proximity to human houses:

“People who have built homes in the jungle near the ocean, however, consider the all-pervasive land crabs quite troublesome. If the crabs can get into the house (they can climb walls!), they can damage clothing, books, and food. Outside of the house, they are quite hard on garden plants, shredding foliage and damaging plant roots from inside their tunnels. By the time November comes, most folks are happy to see the crabs retreat into the ground!” ([27])

These observations demonstrate that human presence does not necessarily have a negative impact on land crabs, as suggested by [5]. The relationship between land crabs and humans might depend on the type of habitat, human settlement system and land use. Exploitation by hunter-gatherers on islands and the introduction of domesticated animals are assumed to have resulted in the extinction of local populations of Gecarcinusruricola ([28]) and a species of Geograpsus ([5]). However, the consumption of land crabs has not been reported from tourist destinations along the Neotropical Pacific coast. As free-roaming domestic animals may be seen as a detriment to tourism ([29]), populations of possible land crab predators/competitors such as pigs, cats, dogs and rats (see [5]) tend to be more controlled than in areas with farmers or hunter-gatherers.

Because gecarcinid land crabs significantly influence tree recruitment by consuming seeds, propagules and seedlings, they are considered important ecosystem engineers (reviewed by [2]). While human presence might open a new evolutionary pathway for these otherwise island restricted land crabs, the colonization of continental mainland forests by a large species such as Johngarthiaplanata (see [18] for a size comparison) would certainly have profound consequences for the structure and species composition of coastal ecosystems, particularly in view of the possibility that their foraging activity would be less restricted due to lower predation pressure. Further surveys for Johngarthiaplanata and possible crab predators/competitors are needed to determine if the known distributional pattern of such species is the result of human influence.

Supplementary MaterialEdit

XML Treatment for JohngarthiaplanataEdit

File:BDJ.2.e1161-treatment1.xml

AcknowledgementsEdit

Thanks are extended to Daniel Brewer, María Elena Valencia, Tania Beagley-Brown, Derek Zoebelein and Mike Gardiner for granting permission to publish their excellent photographs of Johngarthiaplanata and to Daniel Brewer for providing useful information on Johngarthiaplanata in Sayulita. I also thank Hsi-Te Shih (Department of Life Science, National Chung Hsing University, Taiwan) for making available a copy of Manrique (1981), and Richard Hartnoll (School of Biological Sciences, University of Liverpool), David Wilcox (USA), Lyubomir Penev (Bulgarian Academy of Science, Sofia), Niamh Kilgallen (Australian Museum, Sydney) and the anonymous reviewer for providing suggestions on an earlier draft of this manuscript.

ReferencesEdit

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