Skip to main content

Brent Thoma

Jackson State University, Biology, Faculty Member

Followers

62

Following

15

Public Views

Phone: 601-979-3461
Address: Department of Biology
Jackson State University
PO Box 18540
Jackson, MS 39217

less

FDA

William Santana

Universidade do Sagrado Coração - Brasil

Western Australian Museum

University of Kerala

Universidade Federal do Ceará

National University of Singapore

University of Kerala

J.c. Vaupel Klein

Leiden University

InterestsView All (49)

Uploads

Papers by Brent Thoma

A new genus and species of xanthoid crab (Decapoda: Brachyura) from offshore hard bank habitats in the Gulf of Mexico

Zootaxa

Speciose populations of small xanthoid crabs on offshore banks and reefs of the northern Gulf of ... more Speciose populations of small xanthoid crabs on offshore banks and reefs of the northern Gulf of Mexico include a new species that is not assignable to presently named genera. Morphological diagnoses of the new genus and species are underpinned by previously published gene sequence analyses, originally misattributed to another species but now known to apply to this taxon. Herein named Guinope tiara n. gen., n. sp., the species shows molecular phylogenetic affinities with the family Linnaeoxanthidae Števčić, 2005, an ally of panopeid and pseudorhombilid crabs. Specimens from Occulina banks off the Florida Atlantic coast, previously regarded to represent Garthiope barbadensis (Rathbun, 1921), are not that species but instead morphologically assignable to Guinope n. gen. Whether they represent variants of Guinope tiara n. gen, n. sp. or a second species of the genus awaits the collection of fresh materials for DNA analyses.

Polycheria josephensis, a new species of symbiotic amphipod (Crustacea, Amphipoda, Dexaminidae) from the Northern Gulf of Mexico, with notes on its ecology

Polycheria josephensis sp. n. (Dexaminidae), an ascidian symbiont, is described from St. Joseph B... more Polycheria josephensis sp. n. (Dexaminidae), an ascidian symbiont, is described from St. Joseph Bay, Florida and other locations in the Gulf of Mexico and the nearshore Atlantic Ocean from South Carolina to northern Florida. Observations on its ecology, behavior, and distribution are provided. Polycheria josephensis sp. n. is morphologically most similar to Polycheria osborni Calman, 1898 from the Pacific coast of North America. Polycheria josephensis sp. n. differs from P. osborni in the number, spacing and size of the spines on the inner plate of the maxilliped and the shape of the distal margins of coxae 1-7.

Evolution of American mud crabs (Crustacea, Decapoda, Brachyura, Xanthoidea) inferred from nuclear and mitochondrial markers with comments on adult morphology.

Zoological Journal of the Linnaean Society., 2014

Members of the brachyuran crab superfamily Xanthoidea sensu Ng, Guinot & Davie (2008) are a morph... more Members of the brachyuran crab superfamily Xanthoidea sensu Ng, Guinot & Davie (2008) are a morphologically and ecologically diverse assemblage encompassing more than 780 nominal species. On the basis of morphology, Xanthoidea is presently regarded to represent three families: Xanthidae, Pseudorhombilidae, and Panopeidae. However, few studies have examined this superfamily using modern phylogenetic methods, despite the ecological and economic importance of this large, poorly understood group. In this study we examine phylogenetic relationships within the superfamily Xanthoidea using three mitochondrial markers, 12S rRNA, 16S rRNA, and cytochrome oxidase I (COI), and three nuclear markers, 18S rRNA, enolase (ENO) and histone H3 (H3). Bayesian and maximum-likelihood analyses indicate that the superfamily Xanthoidea is monophyletic; however, the families Xanthidae, Panopeidae, and Pseudorhombilidae, as defined by Ng et al., are not, and their representative memberships must be redefined. To this end, some relevant morphological characters are discussed.

Phylogeny of eriphioid crabs (Brachyura, Eriphioidea) inferred from molecular and morphological studies.

Zoologica Scripta, 2014

The evolutionary relationships of the brachyuran crab superfamily Eriphioidea, commonly known as ... more The evolutionary relationships of the brachyuran crab superfamily Eriphioidea, commonly known as stone or rubble crabs, are examined. Analysis of three mitochondrial (12S, 16S and COI) and two nuclear loci (18S and Histone 3) was carried out for 51 taxa representing the Carpilioidea, Dairoidea, Eriphioidea, Goneplacoidea, Parthenopoidea, Pilumnoidea, Portunoidea, Pseudozioidea and Xanthoidea. Phylogenetic analyses of molecular data used three methods of inference that recovered similar topologies with minor differences. Maximum parsimony analysis of 20 morphological characters taken from first zoeas of 11 species
yielded two equally parsimonious trees and generally supported the molecular analyses. None of the analyses recovered Eriphioidea as monophyletic, and each of the eriphioid families represented by two or more taxa was shown to be polyphyletic in both molecular and larval analyses. This study indicates that the present classification based on adult morphology is incongruent with phylogenetic relationships and that the diagnostic characters the result of convergence (particularly in feeding morphology) rather than shared ancestry.

A new genus for Chlorodiella longimana (H. Milne Edwards, 1834) supported by morphology and molecular data, and a preliminary phylogeny of the subfamily Chlorodiellinae (Crustacea: Decapoda: Xanthidae).

Invertebrate Systematics, 2013

Chlorodiella longimana is the only chlorodielline species presently known from the western Atlant... more Chlorodiella longimana is the only chlorodielline species presently known from the western Atlantic Ocean. Although C. longimana superficially resembles other species of the genus in general appearance of the carapace, morphological analyses revealed a suite of characters that separate it from all other known species of Chlorodiella – in particular, ambulatory legs having dactyli with a single tip and a basal antennal segment with a lateral flange that extends halfway into the orbital hiatus, excluding the antennal flagellum. In addition, a phylogenetic analysis of the Chlorodiellinae
inferred from three mitochondrial markers (12S, 16S,COXI) and a nuclear marker (histone H3), confirms that C. longimana is genetically distinct from its congeners. A new genus, Ratha, is proposed to accommodate C. longimana. In addition, a phylogenetic analysis of six chlorodielline genera indicates that the subfamily is polyphyletic as presently defined.

Review of the family Platyxanthidae Guinot, 1977 (Crustacea, Decapoda, Brachyura, Eriphioidea), with the description of a new genus and a key to genera and species

Zootaxa, 2012

During recent studies of phylogenetic relationships within Eriphioidea (sensu Ng et al. 2008), we... more During recent studies of phylogenetic relationships within Eriphioidea (sensu Ng et al. 2008), we recovered molecular evidence that the genus Platyxanthus A. Milne-Edwards, 1863, was not monophyletic. This prompted detailed morphological examination of the group, which confirmed that clear differences in characteristics of the carapace, first male pleopod, antennae, antennules, epistome, abdomen, and thoracic sternum serve to separate the species of Platyxanthus into three distinct groups. Comparison of the type material of Peloeus cokeri (Rathbun, 1930), (formerly Platyxanthus cokeri) to Peloeus armatus Eydoux & Souleyet, 1842, indicated that P. cokeri is a junior synonym of P. armatus and that Gordonoxanthus Števčić, 2011 (type species Platyxanthus cokeri Rathbun, 1930) is thus a junior synonym of Peloeus. Danielethus n. gen. is described to accommodate Platyxanthus patagonicus A. Milne-Edwards, 1863, and Platyxanthus crenulatus A. Milne-Edwards, 1863. A key to the known genera and species of the family Platyxanthidae Guinot, 1977 is provided.

Redescription of Hexapanopeus lobipes, and its reassignment to Milnepanopeus n. gen. (Decapoda: Brachyura: Panopeidae)

Milnepanopeus n. gen. is proposed to accommodate the western Atlantic brachyuran crab, Hexapanope... more Milnepanopeus n. gen. is proposed to accommodate the western Atlantic brachyuran crab, Hexapanopeus lobipes. Characters of the carapace, sternal groove, carpus of the ambulatory pereiopods, and male first gonopod define this presently monospecific genus. Recent molecular analyses support removal of H. lobipes from Hexapanopeus, and segregate this genus as a distinct lineage of Panopeidae Ortmann, 1893. The species is redescribed as Milnepanopeus lobipes, n. comb., on the basis of the holotype and supplementary material from deep banks in the Gulf of Mexico. Variations in morphology are addressed along with morphological comparisons to related genera of the family.

Notes on crabs of the families Goneplacidae and Dorippidae (Decapoda: Brachyura) from the Dampier Archipelago, Western Australia

Nineteen specimens representing four species in the brachyuran families Goneplacidae and Dorippid... more Nineteen specimens representing four species in the brachyuran families Goneplacidae and Dorippidae were collected during a four year biological survey of the Dampier Archipelago, in northwest Western Australia, conducted by the Western Australia Museum. Two of the species are goneplacids, Eucrate affinis and E. dorsalis and the other two are dorippids, Dorippe quadridens and Paradorippe australiensis. Notes on range extensions, habitats, etc., are provided for these four species.

Description of Etisus guinotae n. sp., and discussion of its recent discovery in the Gulf of Mexico (Brachyura, Decapoda, Xanthidae)

Recent collecting efforts on continental shelf banks in the Gulf of Mexico have produced material... more Recent collecting efforts on continental shelf banks in the Gulf of Mexico have produced material of a previously unknown but colorful and conspicuous xanthoid crab, herewith assigned to the species, Etisus guinotae n. sp. Initial collection of a single specimen from the eastern Gulf of Mexico in 2004 raised suspicion that it was an introduction or morphological anomaly of some known species, but exhaustive searches of world literature and consultations with colleagues produced no clear evidence of its identity. Subsequent discovery of additional specimens on banks in the northwestern Gulf of Mexico during August 2008 revealed presence of this species in habitats where it was not found during extensive sampling over 12 previous years and provided additional materials that confirmed its unique characters. Molecular genetic analyses based on 16S mt, 12S mt, and Histone 3 nuclear genes position this species among other Xanthidae sensu stricto, and morphological comparisons place it nearest Indo-West Pacific representatives of Etisus, the genus to which it is provisionally assigned.

A New Species of Parapinnixa (Decapoda: Brachyura: Pinnotheridae) From Isla Del Coco, Costa Rica

Proceedings of the Biological Society of …, Jan 1, 2005

Range Extensions and Review of the Caprellid Amphipods (Crustacea: Amphipoda: Caprellidae) From the Shallow, Coastal Waters From the Suwannee River, …

Gulf and Caribbean Research, Jan 1, 2004

A Guide to the Thalassinidea (Crustacea: Malacostraca: Decapoda) of the South Atlantic Bight

A New Species of the Genus Gammarus (Crustacea: Amphipoda: Gammaridae) From the Low Salinity Habitats In the Northern Gulf of Mexico

Zootaxa, Jan 1, 2015

Molecular Phylogeny of Western Atlantic Representatives of the Genus Hexapanopeus (Decapoda: Brachyura: Panopeidae)

brentthoma.net

Redescription of Pinnixa Arenicola Rathbun, 1922 (Decapoda: Brachyura: Pinnotheridae), With New Observations on Its Range and Host

Proceedings of the Biological Society of …, Jan 1, 2009

Stomatopoda (Crustacea: Hoplocarida) From the Shallow, Inshore Waters of the Northern Gulf of Mexico (Apalachicola River, Florida to Port Aransas, Texas)

Gulf and Caribbean Research, Jan 1, 2004

A new genus and species of xanthoid crab (Decapoda: Brachyura) from offshore hard bank habitats in the Gulf of Mexico

Zootaxa

Speciose populations of small xanthoid crabs on offshore banks and reefs of the northern Gulf of ... more Speciose populations of small xanthoid crabs on offshore banks and reefs of the northern Gulf of Mexico include a new species that is not assignable to presently named genera. Morphological diagnoses of the new genus and species are underpinned by previously published gene sequence analyses, originally misattributed to another species but now known to apply to this taxon. Herein named Guinope tiara n. gen., n. sp., the species shows molecular phylogenetic affinities with the family Linnaeoxanthidae Števčić, 2005, an ally of panopeid and pseudorhombilid crabs. Specimens from Occulina banks off the Florida Atlantic coast, previously regarded to represent Garthiope barbadensis (Rathbun, 1921), are not that species but instead morphologically assignable to Guinope n. gen. Whether they represent variants of Guinope tiara n. gen, n. sp. or a second species of the genus awaits the collection of fresh materials for DNA analyses.

Polycheria josephensis, a new species of symbiotic amphipod (Crustacea, Amphipoda, Dexaminidae) from the Northern Gulf of Mexico, with notes on its ecology

Polycheria josephensis sp. n. (Dexaminidae), an ascidian symbiont, is described from St. Joseph B... more Polycheria josephensis sp. n. (Dexaminidae), an ascidian symbiont, is described from St. Joseph Bay, Florida and other locations in the Gulf of Mexico and the nearshore Atlantic Ocean from South Carolina to northern Florida. Observations on its ecology, behavior, and distribution are provided. Polycheria josephensis sp. n. is morphologically most similar to Polycheria osborni Calman, 1898 from the Pacific coast of North America. Polycheria josephensis sp. n. differs from P. osborni in the number, spacing and size of the spines on the inner plate of the maxilliped and the shape of the distal margins of coxae 1-7.

Evolution of American mud crabs (Crustacea, Decapoda, Brachyura, Xanthoidea) inferred from nuclear and mitochondrial markers with comments on adult morphology.

Zoological Journal of the Linnaean Society., 2014

Members of the brachyuran crab superfamily Xanthoidea sensu Ng, Guinot & Davie (2008) are a morph... more Members of the brachyuran crab superfamily Xanthoidea sensu Ng, Guinot & Davie (2008) are a morphologically and ecologically diverse assemblage encompassing more than 780 nominal species. On the basis of morphology, Xanthoidea is presently regarded to represent three families: Xanthidae, Pseudorhombilidae, and Panopeidae. However, few studies have examined this superfamily using modern phylogenetic methods, despite the ecological and economic importance of this large, poorly understood group. In this study we examine phylogenetic relationships within the superfamily Xanthoidea using three mitochondrial markers, 12S rRNA, 16S rRNA, and cytochrome oxidase I (COI), and three nuclear markers, 18S rRNA, enolase (ENO) and histone H3 (H3). Bayesian and maximum-likelihood analyses indicate that the superfamily Xanthoidea is monophyletic; however, the families Xanthidae, Panopeidae, and Pseudorhombilidae, as defined by Ng et al., are not, and their representative memberships must be redefined. To this end, some relevant morphological characters are discussed.

Phylogeny of eriphioid crabs (Brachyura, Eriphioidea) inferred from molecular and morphological studies.

Zoologica Scripta, 2014

The evolutionary relationships of the brachyuran crab superfamily Eriphioidea, commonly known as ... more The evolutionary relationships of the brachyuran crab superfamily Eriphioidea, commonly known as stone or rubble crabs, are examined. Analysis of three mitochondrial (12S, 16S and COI) and two nuclear loci (18S and Histone 3) was carried out for 51 taxa representing the Carpilioidea, Dairoidea, Eriphioidea, Goneplacoidea, Parthenopoidea, Pilumnoidea, Portunoidea, Pseudozioidea and Xanthoidea. Phylogenetic analyses of molecular data used three methods of inference that recovered similar topologies with minor differences. Maximum parsimony analysis of 20 morphological characters taken from first zoeas of 11 species
yielded two equally parsimonious trees and generally supported the molecular analyses. None of the analyses recovered Eriphioidea as monophyletic, and each of the eriphioid families represented by two or more taxa was shown to be polyphyletic in both molecular and larval analyses. This study indicates that the present classification based on adult morphology is incongruent with phylogenetic relationships and that the diagnostic characters the result of convergence (particularly in feeding morphology) rather than shared ancestry.

A new genus for Chlorodiella longimana (H. Milne Edwards, 1834) supported by morphology and molecular data, and a preliminary phylogeny of the subfamily Chlorodiellinae (Crustacea: Decapoda: Xanthidae).

Invertebrate Systematics, 2013

Chlorodiella longimana is the only chlorodielline species presently known from the western Atlant... more Chlorodiella longimana is the only chlorodielline species presently known from the western Atlantic Ocean. Although C. longimana superficially resembles other species of the genus in general appearance of the carapace, morphological analyses revealed a suite of characters that separate it from all other known species of Chlorodiella – in particular, ambulatory legs having dactyli with a single tip and a basal antennal segment with a lateral flange that extends halfway into the orbital hiatus, excluding the antennal flagellum. In addition, a phylogenetic analysis of the Chlorodiellinae
inferred from three mitochondrial markers (12S, 16S,COXI) and a nuclear marker (histone H3), confirms that C. longimana is genetically distinct from its congeners. A new genus, Ratha, is proposed to accommodate C. longimana. In addition, a phylogenetic analysis of six chlorodielline genera indicates that the subfamily is polyphyletic as presently defined.

Review of the family Platyxanthidae Guinot, 1977 (Crustacea, Decapoda, Brachyura, Eriphioidea), with the description of a new genus and a key to genera and species

Zootaxa, 2012

During recent studies of phylogenetic relationships within Eriphioidea (sensu Ng et al. 2008), we... more During recent studies of phylogenetic relationships within Eriphioidea (sensu Ng et al. 2008), we recovered molecular evidence that the genus Platyxanthus A. Milne-Edwards, 1863, was not monophyletic. This prompted detailed morphological examination of the group, which confirmed that clear differences in characteristics of the carapace, first male pleopod, antennae, antennules, epistome, abdomen, and thoracic sternum serve to separate the species of Platyxanthus into three distinct groups. Comparison of the type material of Peloeus cokeri (Rathbun, 1930), (formerly Platyxanthus cokeri) to Peloeus armatus Eydoux & Souleyet, 1842, indicated that P. cokeri is a junior synonym of P. armatus and that Gordonoxanthus Števčić, 2011 (type species Platyxanthus cokeri Rathbun, 1930) is thus a junior synonym of Peloeus. Danielethus n. gen. is described to accommodate Platyxanthus patagonicus A. Milne-Edwards, 1863, and Platyxanthus crenulatus A. Milne-Edwards, 1863. A key to the known genera and species of the family Platyxanthidae Guinot, 1977 is provided.

Redescription of Hexapanopeus lobipes, and its reassignment to Milnepanopeus n. gen. (Decapoda: Brachyura: Panopeidae)

Milnepanopeus n. gen. is proposed to accommodate the western Atlantic brachyuran crab, Hexapanope... more Milnepanopeus n. gen. is proposed to accommodate the western Atlantic brachyuran crab, Hexapanopeus lobipes. Characters of the carapace, sternal groove, carpus of the ambulatory pereiopods, and male first gonopod define this presently monospecific genus. Recent molecular analyses support removal of H. lobipes from Hexapanopeus, and segregate this genus as a distinct lineage of Panopeidae Ortmann, 1893. The species is redescribed as Milnepanopeus lobipes, n. comb., on the basis of the holotype and supplementary material from deep banks in the Gulf of Mexico. Variations in morphology are addressed along with morphological comparisons to related genera of the family.

Notes on crabs of the families Goneplacidae and Dorippidae (Decapoda: Brachyura) from the Dampier Archipelago, Western Australia

Nineteen specimens representing four species in the brachyuran families Goneplacidae and Dorippid... more Nineteen specimens representing four species in the brachyuran families Goneplacidae and Dorippidae were collected during a four year biological survey of the Dampier Archipelago, in northwest Western Australia, conducted by the Western Australia Museum. Two of the species are goneplacids, Eucrate affinis and E. dorsalis and the other two are dorippids, Dorippe quadridens and Paradorippe australiensis. Notes on range extensions, habitats, etc., are provided for these four species.

Description of Etisus guinotae n. sp., and discussion of its recent discovery in the Gulf of Mexico (Brachyura, Decapoda, Xanthidae)

Recent collecting efforts on continental shelf banks in the Gulf of Mexico have produced material... more Recent collecting efforts on continental shelf banks in the Gulf of Mexico have produced material of a previously unknown but colorful and conspicuous xanthoid crab, herewith assigned to the species, Etisus guinotae n. sp. Initial collection of a single specimen from the eastern Gulf of Mexico in 2004 raised suspicion that it was an introduction or morphological anomaly of some known species, but exhaustive searches of world literature and consultations with colleagues produced no clear evidence of its identity. Subsequent discovery of additional specimens on banks in the northwestern Gulf of Mexico during August 2008 revealed presence of this species in habitats where it was not found during extensive sampling over 12 previous years and provided additional materials that confirmed its unique characters. Molecular genetic analyses based on 16S mt, 12S mt, and Histone 3 nuclear genes position this species among other Xanthidae sensu stricto, and morphological comparisons place it nearest Indo-West Pacific representatives of Etisus, the genus to which it is provisionally assigned.

A New Species of Parapinnixa (Decapoda: Brachyura: Pinnotheridae) From Isla Del Coco, Costa Rica

Proceedings of the Biological Society of …, Jan 1, 2005

Range Extensions and Review of the Caprellid Amphipods (Crustacea: Amphipoda: Caprellidae) From the Shallow, Coastal Waters From the Suwannee River, …

Gulf and Caribbean Research, Jan 1, 2004

A Guide to the Thalassinidea (Crustacea: Malacostraca: Decapoda) of the South Atlantic Bight

A New Species of the Genus Gammarus (Crustacea: Amphipoda: Gammaridae) From the Low Salinity Habitats In the Northern Gulf of Mexico

Zootaxa, Jan 1, 2015

Molecular Phylogeny of Western Atlantic Representatives of the Genus Hexapanopeus (Decapoda: Brachyura: Panopeidae)

brentthoma.net

Redescription of Pinnixa Arenicola Rathbun, 1922 (Decapoda: Brachyura: Pinnotheridae), With New Observations on Its Range and Host

Proceedings of the Biological Society of …, Jan 1, 2009

Stomatopoda (Crustacea: Hoplocarida) From the Shallow, Inshore Waters of the Northern Gulf of Mexico (Apalachicola River, Florida to Port Aransas, Texas)

Gulf and Caribbean Research, Jan 1, 2004