Pablo Hernández-Alcántara - Academia.edu (original) (raw)
Papers by Pablo Hernández-Alcántara
Spatial variations of polychaetes along the Baja California Peninsula continental shelf were anal... more Spatial variations of polychaetes along the Baja California Peninsula continental shelf were analysed in two ways: (1) by evaluating the species richness and defining the faunal assemblages from local sampling, and (2) by characterizing the latitudinal variation of beta-diversity based on the distribution of all polychaetes reported up to now. Twenty-seven stations from
three oceanographic expeditions were sampled, and 2858 individuals from 38 families and 231 species were identified. Polychaetes were abundant (mean= 37.5 ind/0.1 m2) and diversified (mean= 15 species/station). Differences in species composition defined seven faunal assemblages, but their number of species did not show significant latitudinal changes. The beta-diversity analysis was based on distribution data of 730 species from 47 families. The presence of a group of islands in the middle Gulf could have a negative effect on the species distribution, since the lowest values of beta-diversity (0.39) were found in the northern Gulf, but their species were different from those recorded in the central
region. The wide variation in beta-diversity (0.5–0.87) showed latitudinal changes in the species composition, mainly in the Gulf mouth (0.86–0.87), which indicated that the fauna inside the Gulf was different from that inhabiting the Pacific coasts. The ICE and Chao2 estimators showed that the polychaetes in the study area are relatively well known (>80%), and that most species (415) have small distribution ranges. The effects of these infrequent species were similar at each latitudinal band, which suggested that the observed beta-diversity pattern could represent a suitable stimation.
Paradiopatra multibranchiata, an onuphid found commonly in shelf sediments of the tropical easter... more Paradiopatra multibranchiata, an onuphid found commonly in shelf sediments of the tropical eastern Pacific, is described here. It belongs to the group of Paradiopatra species characterized by the presence of branchiae on the most anterior parapodia (chaetigers 2–3), with at least seven filaments when fully developed. The new species closely resembles P. parva, also distributed in the eastern Pacific but in temperate habitats. It can be distinguished from the latter by the presence rather than the absence of eyes, and because
it bears the highest number of branchial filaments (up to 37) observed in any Paradiopatra species known so far (14–18 filaments at most). The taxonomic status of the new species is supported by comparative morphometric and multivariate analyses, which also allowed us to
verify its differences with P. parva. The branchial development was the most useful character to determine the relationships between the specimens of P. multibranchiata sp. nov., while its separation from P. parva (Wilks’ lambda = 0.060, P < 0.0001) was weighted most heavily by the number of filaments at chaetigers 2 and 10, and the length of the median antenna. An
anatomical examination with methylene blue stain and with scanning electron microscopy was carried out to illustrate the ventral glandular pad staining pattern and the features of their cuticular pores.
Hydrobiologia, 2000
The deep water polychaete fauna is analyzed in this study particularly regarding its composition ... more The deep water polychaete fauna is analyzed in this study particularly regarding its composition and variations with depth in the Sigsbee Basin, northwestern region of the Gulf of Mexico. Samples were taken at 10 stations along a bathymetric gradient with depth ranges from 200 to 3760 m with a USNEL (0.25 m 2 ) corer. A total of 287 individuals were identified, from 21 families and 65 species. The most important families, both in terms of abundance and species richness, were: Paraonidae (65.4 ind./0.25 m 2 , 9 spp.), Cirratulidae (28.93 ind./0.25 m 2 , 7 spp.) and Spionidae (18.07 ind./0.25 m 2 , 7 spp.). In general, density tended to decrease with depth with minima at around 2000 m, although two abundance peaks were detected at 3700 and 3760 m, making the pattern seem an inverted parabolic curve. The Shannon-Wiener diversity values varied from 0.54-0.92 at around 2000 m to 3.39 at 3620 m and 3.34 at 3760 m. These results contrast with what is already reported from the North Atlantic and the Tropical Pacific deep benthic communities, where highest diversities are found at 2000 m. Faunal changes evaluated through Beta Diversity (0.08-0.1) and the low similarity found between the stations, emphasized the high variability in the composition of the fauna in the Sigsee Basin, meaning that the faunal composition is practically different at all the sampling stations. Ten species are newly recorded for the Mexican fauna.
Memoirs of Museum Victoria
Hernández-Alcántara, P., Cortés-Solano, J.D., Medina-Cantú, N.M., Avilés-Díaz, A.L. and Solís-Wei... more Hernández-Alcántara, P., Cortés-Solano, J.D., Medina-Cantú, N.M., Avilés-Díaz, A.L. and Solís-Weiss, V. 2014. Polychaete diversity in the estuarine habitats of Términos Lagoon, Southern Gulf of Mexico. Memoirs of Museum Victoria 71: 97-107.
Zootaxa, 2013
The aim of this study was to analyze the taxonomy and distribution of the polychaetes of the fami... more The aim of this study was to analyze the taxonomy and distribution of the polychaetes of the family Paraonidae from a lagoon-estuarine ecosystem in the Gulf of Mexico. The samples come from 20 soft bottom stations in the Términos Lagoon during the dry and rainy seasons, of which eight included paraonids. In all, 1183 specimens belonging to two new species were identified: Aricidea (Acmira) hirsuta (1125 specimens) and Paradoneis carmelitensis (58 specimens). A. (A.) hirsuta is clearly distinguished from other members of the genus by the presence of unidentate curved spines with a dense pubescence along their medium and distal margins, and because the median antenna is short. P carmelitensis is mainly characterized by the absence of eyes, by the presence of triangular shaped postchaetal prebranchial lobes, and the presence of branchiae and lyriform chaetae from chaetiger 4. The paraonids occurrence was mainly associated with salinities close to marine conditions (31.71 to 35.85 psu)....
Zootaxa, 2015
Endoparasitic relationships among polychaetes are uncommon and mostly restricted to about 20 spec... more Endoparasitic relationships among polychaetes are uncommon and mostly restricted to about 20 species of the family Oenonidae. We herein describe Labrorostratus caribensis, a new oenonid species living in the body cavity of a nereidid polychaete in Chinchorro Bank (Mexican Caribbean). This is the first report of a parasitic relationship between oenonids and nereidids in the Grand Caribbean region. The new species is diagnosed by the jaw apparatus reduced to only maxillary carriers fused, one simple modified ventral chaeta from midbody and lack of acicular spines. The generic diagnosis is emended to include species without maxillary plates. A synopsis of parasitism among polychaetes worldwide is presented.
Zootaxa, 2015
A new species of polychaete, Nereis alacranensis n. sp., was found in dead coral rocks in the int... more A new species of polychaete, Nereis alacranensis n. sp., was found in dead coral rocks in the intertidal zone of Alacranes reef, southern Gulf of Mexico. N. alacranensis n. sp. can be included in a group of nereidids characterized by the absence of paragnaths in areas I and V of the pharynx, the presence of cones in a single row or absent in areas VII-VIII, and short blades in notopodial homogomph falcigers. The new species can be separated from the other species of the group by the presence of 3-7 cones in area VI and 7 cones arranged in a row in areas VII-VIII, finely dentate blades in notopodial homogomph falcigers, but most of all, by the presence of an unusual brown coarse arc shaped plate on the external ventral region of the peristomium. This structure has not yet been reported, at least in this genus. A taxonomic key of the species of Nereis recorded from the Grand Caribbean region is included.
Revista de biologia tropical
Revista de biologia tropical
Proceedings of the Biological Society of Washington
Revista de biologia tropical
The composítion of the benthic macrofauna associated with the red mangrove (Rhizophora mangle) in... more The composítion of the benthic macrofauna associated with the red mangrove (Rhizophora mangle) in Térmi nos Lagoon, Mexico, were analyzed together with some ecologicaJ parameters. Five sampling stations, were chosen re flecting the conttasting environmental conditions prevailing in the Lagoon, (marine or freshwater influence). The sam pies (0.3 m 2 of sediment) were collected at three month intervals between May 1983 and May 1984 with a corer (20 cm in diameter), and sieved through a 0.5 mm mesh screen. We found 3757 organísms of tbree taxa: Polychaeta (22 fami lies, 43 species), Mollusca (11 fanúlies, 17 species) and Crustacea (20 families, 27 species). The polychaetes dominated in each sample. Capitella .. capitata ", Mediomastus califomiensis, Laeonereis culveri, Streblospio benedicti, Lembos sp, Lucína pectinata, Palaemonetes vulgaris, Melínna maculata, Tellina lineata. Xenanthura sp . Tellina altemata tayloria na ami Parandalia vivianneae were the most abundant species, although not present at evety station, presumably becau se oC the contrasting environmental conditions. The híghest abundances were registered at stations under marine influen ce, especially during the rainy and winter seasons. Diversity fluctuated at each station; the híghest values were recorded in the southem (2.11 on average) and northeastem (2.06 on average) regions.
Bulletin of Marine Science -Miami-
We analyzed 556 specimens from the family Magelonidae collected during surveys made along the con... more We analyzed 556 specimens from the family Magelonidae collected during surveys made along the continental shelf of the Pacific coasts of Mexico (Gulf of California, Gulf of Tehuantepec, and the state of Guerrero). The study area covers latitudes 15°35′N to 31°20′N and longitudes 94°00′W to 114°23′W. Additional material from the northern Gulf of Mexico (USA region) belonging to the USNM collections was also examined. Earlier records of magelonids in the Mexican Pacific include Magelona pacifica, M. pitelkai, M. sacculata, and M. californica. A new genus (Meredithia), characterized by the presence of acicular spines in abdominal parapodia, as well as four new magelonid species are described. Affinities to related species in both genera (Magelona and Meredithia) are discussed. Magelona marianae is the only species in the genus with bidentate hooded hooks and notopodial lateral lamellae distally crenulate. In Magelona tehuanensis, the tip of the prostomium is crenulate with frontal horn...
Spatial variations of polychaetes along the Baja California Peninsula continental shelf were anal... more Spatial variations of polychaetes along the Baja California Peninsula continental shelf were analysed in two ways: (1) by evaluating the species richness and defining the faunal assemblages from local sampling, and (2) by characterizing the latitudinal variation of beta-diversity based on the distribution of all polychaetes reported up to now. Twenty-seven stations from
three oceanographic expeditions were sampled, and 2858 individuals from 38 families and 231 species were identified. Polychaetes were abundant (mean= 37.5 ind/0.1 m2) and diversified (mean= 15 species/station). Differences in species composition defined seven faunal assemblages, but their number of species did not show significant latitudinal changes. The beta-diversity analysis was based on distribution data of 730 species from 47 families. The presence of a group of islands in the middle Gulf could have a negative effect on the species distribution, since the lowest values of beta-diversity (0.39) were found in the northern Gulf, but their species were different from those recorded in the central
region. The wide variation in beta-diversity (0.5–0.87) showed latitudinal changes in the species composition, mainly in the Gulf mouth (0.86–0.87), which indicated that the fauna inside the Gulf was different from that inhabiting the Pacific coasts. The ICE and Chao2 estimators showed that the polychaetes in the study area are relatively well known (>80%), and that most species (415) have small distribution ranges. The effects of these infrequent species were similar at each latitudinal band, which suggested that the observed beta-diversity pattern could represent a suitable stimation.
Paradiopatra multibranchiata, an onuphid found commonly in shelf sediments of the tropical easter... more Paradiopatra multibranchiata, an onuphid found commonly in shelf sediments of the tropical eastern Pacific, is described here. It belongs to the group of Paradiopatra species characterized by the presence of branchiae on the most anterior parapodia (chaetigers 2–3), with at least seven filaments when fully developed. The new species closely resembles P. parva, also distributed in the eastern Pacific but in temperate habitats. It can be distinguished from the latter by the presence rather than the absence of eyes, and because
it bears the highest number of branchial filaments (up to 37) observed in any Paradiopatra species known so far (14–18 filaments at most). The taxonomic status of the new species is supported by comparative morphometric and multivariate analyses, which also allowed us to
verify its differences with P. parva. The branchial development was the most useful character to determine the relationships between the specimens of P. multibranchiata sp. nov., while its separation from P. parva (Wilks’ lambda = 0.060, P < 0.0001) was weighted most heavily by the number of filaments at chaetigers 2 and 10, and the length of the median antenna. An
anatomical examination with methylene blue stain and with scanning electron microscopy was carried out to illustrate the ventral glandular pad staining pattern and the features of their cuticular pores.
Hydrobiologia, 2000
The deep water polychaete fauna is analyzed in this study particularly regarding its composition ... more The deep water polychaete fauna is analyzed in this study particularly regarding its composition and variations with depth in the Sigsbee Basin, northwestern region of the Gulf of Mexico. Samples were taken at 10 stations along a bathymetric gradient with depth ranges from 200 to 3760 m with a USNEL (0.25 m 2 ) corer. A total of 287 individuals were identified, from 21 families and 65 species. The most important families, both in terms of abundance and species richness, were: Paraonidae (65.4 ind./0.25 m 2 , 9 spp.), Cirratulidae (28.93 ind./0.25 m 2 , 7 spp.) and Spionidae (18.07 ind./0.25 m 2 , 7 spp.). In general, density tended to decrease with depth with minima at around 2000 m, although two abundance peaks were detected at 3700 and 3760 m, making the pattern seem an inverted parabolic curve. The Shannon-Wiener diversity values varied from 0.54-0.92 at around 2000 m to 3.39 at 3620 m and 3.34 at 3760 m. These results contrast with what is already reported from the North Atlantic and the Tropical Pacific deep benthic communities, where highest diversities are found at 2000 m. Faunal changes evaluated through Beta Diversity (0.08-0.1) and the low similarity found between the stations, emphasized the high variability in the composition of the fauna in the Sigsee Basin, meaning that the faunal composition is practically different at all the sampling stations. Ten species are newly recorded for the Mexican fauna.
Memoirs of Museum Victoria
Hernández-Alcántara, P., Cortés-Solano, J.D., Medina-Cantú, N.M., Avilés-Díaz, A.L. and Solís-Wei... more Hernández-Alcántara, P., Cortés-Solano, J.D., Medina-Cantú, N.M., Avilés-Díaz, A.L. and Solís-Weiss, V. 2014. Polychaete diversity in the estuarine habitats of Términos Lagoon, Southern Gulf of Mexico. Memoirs of Museum Victoria 71: 97-107.
Zootaxa, 2013
The aim of this study was to analyze the taxonomy and distribution of the polychaetes of the fami... more The aim of this study was to analyze the taxonomy and distribution of the polychaetes of the family Paraonidae from a lagoon-estuarine ecosystem in the Gulf of Mexico. The samples come from 20 soft bottom stations in the Términos Lagoon during the dry and rainy seasons, of which eight included paraonids. In all, 1183 specimens belonging to two new species were identified: Aricidea (Acmira) hirsuta (1125 specimens) and Paradoneis carmelitensis (58 specimens). A. (A.) hirsuta is clearly distinguished from other members of the genus by the presence of unidentate curved spines with a dense pubescence along their medium and distal margins, and because the median antenna is short. P carmelitensis is mainly characterized by the absence of eyes, by the presence of triangular shaped postchaetal prebranchial lobes, and the presence of branchiae and lyriform chaetae from chaetiger 4. The paraonids occurrence was mainly associated with salinities close to marine conditions (31.71 to 35.85 psu)....
Zootaxa, 2015
Endoparasitic relationships among polychaetes are uncommon and mostly restricted to about 20 spec... more Endoparasitic relationships among polychaetes are uncommon and mostly restricted to about 20 species of the family Oenonidae. We herein describe Labrorostratus caribensis, a new oenonid species living in the body cavity of a nereidid polychaete in Chinchorro Bank (Mexican Caribbean). This is the first report of a parasitic relationship between oenonids and nereidids in the Grand Caribbean region. The new species is diagnosed by the jaw apparatus reduced to only maxillary carriers fused, one simple modified ventral chaeta from midbody and lack of acicular spines. The generic diagnosis is emended to include species without maxillary plates. A synopsis of parasitism among polychaetes worldwide is presented.
Zootaxa, 2015
A new species of polychaete, Nereis alacranensis n. sp., was found in dead coral rocks in the int... more A new species of polychaete, Nereis alacranensis n. sp., was found in dead coral rocks in the intertidal zone of Alacranes reef, southern Gulf of Mexico. N. alacranensis n. sp. can be included in a group of nereidids characterized by the absence of paragnaths in areas I and V of the pharynx, the presence of cones in a single row or absent in areas VII-VIII, and short blades in notopodial homogomph falcigers. The new species can be separated from the other species of the group by the presence of 3-7 cones in area VI and 7 cones arranged in a row in areas VII-VIII, finely dentate blades in notopodial homogomph falcigers, but most of all, by the presence of an unusual brown coarse arc shaped plate on the external ventral region of the peristomium. This structure has not yet been reported, at least in this genus. A taxonomic key of the species of Nereis recorded from the Grand Caribbean region is included.
Revista de biologia tropical
Revista de biologia tropical
Proceedings of the Biological Society of Washington
Revista de biologia tropical
The composítion of the benthic macrofauna associated with the red mangrove (Rhizophora mangle) in... more The composítion of the benthic macrofauna associated with the red mangrove (Rhizophora mangle) in Térmi nos Lagoon, Mexico, were analyzed together with some ecologicaJ parameters. Five sampling stations, were chosen re flecting the conttasting environmental conditions prevailing in the Lagoon, (marine or freshwater influence). The sam pies (0.3 m 2 of sediment) were collected at three month intervals between May 1983 and May 1984 with a corer (20 cm in diameter), and sieved through a 0.5 mm mesh screen. We found 3757 organísms of tbree taxa: Polychaeta (22 fami lies, 43 species), Mollusca (11 fanúlies, 17 species) and Crustacea (20 families, 27 species). The polychaetes dominated in each sample. Capitella .. capitata ", Mediomastus califomiensis, Laeonereis culveri, Streblospio benedicti, Lembos sp, Lucína pectinata, Palaemonetes vulgaris, Melínna maculata, Tellina lineata. Xenanthura sp . Tellina altemata tayloria na ami Parandalia vivianneae were the most abundant species, although not present at evety station, presumably becau se oC the contrasting environmental conditions. The híghest abundances were registered at stations under marine influen ce, especially during the rainy and winter seasons. Diversity fluctuated at each station; the híghest values were recorded in the southem (2.11 on average) and northeastem (2.06 on average) regions.
Bulletin of Marine Science -Miami-
We analyzed 556 specimens from the family Magelonidae collected during surveys made along the con... more We analyzed 556 specimens from the family Magelonidae collected during surveys made along the continental shelf of the Pacific coasts of Mexico (Gulf of California, Gulf of Tehuantepec, and the state of Guerrero). The study area covers latitudes 15°35′N to 31°20′N and longitudes 94°00′W to 114°23′W. Additional material from the northern Gulf of Mexico (USA region) belonging to the USNM collections was also examined. Earlier records of magelonids in the Mexican Pacific include Magelona pacifica, M. pitelkai, M. sacculata, and M. californica. A new genus (Meredithia), characterized by the presence of acicular spines in abdominal parapodia, as well as four new magelonid species are described. Affinities to related species in both genera (Magelona and Meredithia) are discussed. Magelona marianae is the only species in the genus with bidentate hooded hooks and notopodial lateral lamellae distally crenulate. In Magelona tehuanensis, the tip of the prostomium is crenulate with frontal horn...