Vivianne Solís-Weiss

Distribution and diversity of the Syllidae (Annelida: Polychaeta) from the Mexican Gulf of Mexico and Caribbean

The objective of this study was to contribute to the knowledge of the syllids distributed in the eastern coasts of Mexico (Gulf of Mexico and Caribbean) taking into consideration their composition, distribution and diversity. Sampling was done at 77 stations including 49 in soft bottoms (terrigenous and carbonate sediments), and 28 in hard bottoms (coralline substrates) sampled in nine reef zones included in three reef systems (Veracruz, Campeche and Cozumel). In all 2084 individuals were collected (13.5% in soft sediments and 86.4% in coralline areas). Forty-five species were identified: 31 in soft bottoms and 38 in corals, with 21 species common to both types of environments. In soft bottoms, the highest species richness and diversity were found in the Carbonate Zone, while syllids were uncommon in the Terrigenous Zone. In hard bottoms, the highest density, species richness and diversity values were found in the Veracruz Reef System, followed by the Campeche Bank and Cozumel Island Reef Systems. The dominant species in soft bottoms were Haplosyllis spongicola, Exogone lourei, Typosyllis cornuta and T. papillosus, whereas T. alosae, T. corallicola, T. cornuta and H. spongicola dominated in hard bottoms. The importance and success of the syllids in both soft bottoms and reef environments, particularly in those of the Gulf of Mexico is emphasized.

Bathymetric distribution and diversity of deep water polychaetous annelids in the Sigsbee Basin, northwestern Gulf of Mexico

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 m2) 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 m2, 9 spp.), Cirratulidae (28.93 ind./0.25 m2, 7 spp.) and Spionidae (18.07 ind./0.25 m2, 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.

Parasitism among polychaetes : A rare case illustrated by a new species : Labrorostratus zaragozensis, n. sp. (Oenonidae) found in the Gulf of California, Mexico

We describe a new species of polychaetous annelid from the family Oenonidae, Labrorostratus zaragozensis, n. sp., which is parasitic on another polychaete from the family Trichobranchidae (Terebellides californica). It can be differentiated from the other 4 species of the genus (Labrorostratus parasiticus, Labrorostratus jonicus, Labrorostratus prolificus, Labrorostratus sp.), basically by the shape of the mandibles and in the case of L. luteus, by the presence of hooded acicular hooks. Along with the description, a review and discussion of all previous records of the parasites in the Oenonidae and their related interactions with their hosts is presented.

Experimental evidence of pollination in marine flowers by invertebrate fauna

Pollen transport by water-flow (hydrophily) is a typical, and almost exclusive, adaptation of plants to life in the marine environment. It is thought that, unlike terrestrial environments, animals are not involved in pollination in the sea. The male flowers of the tropical marine angiosperm Thalassia testudinum open-up and release pollen in mucilage at night when invertebrate fauna is active. Here we present experimental evidence that, in the absence of water-flow, these invertebrates visit the flowers, carry and transfer mucilage mass with embedded pollen from the male flowers to the stigmas of the female flowers. Pollen tubes are formed on the stigmas, indicating that pollination is successful. Thus, T. testudinum has mixed abiotic–biotic pollination. We propose a zoobenthophilous pollination syndrome (pollen transfer in the benthic zone by invertebrate animals) which shares many characteristics with hydrophily, but flowers are expected to open-up during the night.

Distribution of polychaete feeding guilds in sedimentary environments of the Campeche Bank, Southern Gulf of Mexico

The aim of this study was to analyze the trophic structure of the polychaete assemblages found in the Campeche Bank, southern Gulf of Mexico and to examine the effect of the sediment composition on the spatial distribution of the feeding guilds. In all, 2,662 organisms belonging to 160 species and 16 feeding guilds were identified. Filter-feeders (Fabricinuda trilobata and Bispira melanostigma) dominated. Five groups of stations were defined based on feeding guilds: one, in the southwest, characterized by motile jawed burrowers (17.14% contribution); the second, from the southeast to the northwest, characterized by seven guilds (45.25%), mainly filter-feeders and surface deposit-feeders; the third, in the southwest, characterized by three guilds (42.13%), mainly discretely motile tentaculate filter-feeders and motile unarmed burrowers; group four, in the east, was characterized by sessile tentaculate filter-feeders (63.68%); and group five, in the center and to the north, was characterized by four guilds (53.69%), mainly discretely motile tentaculate filter-feeders. The variety of feeding guilds was higher in the northwest with seven guilds, and the lowest variety was found in the east and south with only one or two guilds. Contrary to the starting hypothesis, the sediment composition was not the main factor that determined the distribution of the polychaete feeding guilds. Instead, salinity and depth were more important for the spatial arrangement of the trophic groups. The feeding guilds of polychaetes proved to be more sensitive to environmental changes than density or diversity.

Hyalella cenotensis, a new species of Hyalellidae (Crustacea: Amphipoda) from the Yucatán Peninsula, Mexico.

In this study the first blind species of Hyalella for Mexico is described; it is the second in the genus to be recorded there. The new species is closer to the eyeless species: H. anophthalma Ruffo, 1957, H. muerta Baldinger, Shepard & Threloff, 2000, H. caeca Pereira, 1989, H. spelaea Bueno & Cardoso, 2011 in Cardoso et al. 2011, H. imbya Rodrigues & Bueno, 2012 in Rodrigues et al. 2012, but with no curved seta at the inner ramus of uropod 1, antennae 1 shorter than antennae 2, no apical setae on the telson and a characteristic dorsoposterior carina and three pappose setae on the inner plate of maxilla 1. The morphological intraspecific variations that can be found in this genus are discussed.

Carapace relative growth of Trapezia Latreille, 1828 (Decapoda, Brachyura), crabs that are symbionts of hard corals, from Clipperton atoll and the Revillagigedo islands: ecological and zoogeographical implications

[Decapod metapopulation dynamics are better understood by confronting theoretical studies with empirical data. In this study, our goal was to analyse the morphometric characteristics and relative growth of the carapace of Trapezia bidentata (Forskal, 1775) and T. digitalis Latreille, 1828, crabs from the islands Clipperton and Revillagigedo, in order to assess the degree of inter- and intraspecific similarity of the four insular populations. We examined 325 specimens and identified four species: T. bidentata (72.9% of total abundance), T. digitalis (23.1%), T. formosa Smith, 1869 (3.4%), and T. corallina Gerstaecker, 1857 (0.6%). Three carapace measurements were taken for each specimen: carapace width (CW), carapace length (CL), and interocular distance (ID). The variables CL and ID were fit to a power equation taking CW as the reference dimension. As in other brachyurans, growth pattern analyses indicated an isometric type in all CW vs CL and CW vs ID relationships examined. Interspecific differences included a larger body size for T. bidentata and larger ID/CW for T. digitalis . Significant intraspecific differences in the two insular populations of T. digitalis were evidenced in the ID/CW ratio. In contrast, populations of T. bidentata were morphometrically closer. These results indicate a higher degree of connectedness of the parts of the T. bidentata metapopulation than of that of T. digitalis , probably due to differences in the duration of their larval stages. We think that the larger body size in T. bidentata might account for competitive advantages in food gathering and habitat selection over the remaining species. In turn, as a counteracting trait for its smaller size, the larger ID might allow T. digitalis a better ability to perceive 3D and to judge relative distances between objects, thus avoiding competitive combats and improving antipredatory or escape responses. La dinamica de las metapoblaciones de decapodos se comprende mejor confrontando estudios teoricos con datos empiricos. En este estudio, nuestro objetivo fue analizar las caracteristicas morfometricas y el crecimiento relativo del caparazon de Trapezia bidentata (Forskal, 1775) y T. digitalis Latreille, 1828, cangrejos de las islas Clipperton y Revillagigedo a fin de determinar el grado de similitud inter- e intraespecifica de las cuatro poblaciones insulares. Se examinaron 325 especimenes e identificaron cuatro especies: T. bidentata (72.9% de la abundancia total), T. digitalis (23.1%), T. formosa Smith, 1869 (3.4%) y T. corallina Gerstaecker, 1857 (0.6%). Para cada especimen, se tomaron tres dimensiones del caparazon: ancho (CW), largo (CL) y distancia interocular (ID). Las variables CL e ID se ajustaron a una ecuacion de tipo potencial tomando CW como la dimension de referencia. Como en otros braquiuros, los analisis del patron de crecimiento mostraron un tipo isometrico en todas las relaciones CW vs CL y CW vs ID examinadas. Las diferencias interespecificas incluyeron un mayor tamano corporal para T. bidentata y un mayor valor en el cociente ID/CW para T. digitalis . Se evidenciaron diferencias significativas intraespecificas entre las dos poblaciones insulares de T. digitalis en el cociente ID/CW. En contraste, las poblaciones de T. bidentata fueron morfometricamente mas semejantes. Estos resultados indican un mayor grado de conectividad en la metapoblacion de T. bidentata que en aquella de T. digitalis , debido probablemente a diferencias en la duracion de sus estados larvarios. Se piensa que la mayor talla corporal de T. bidentata representaria una mayor ventaja competitiva sobre el resto de las especies para atrapar alimento y seleccionar su habitat. A su vez, para contrarrestar su pequeno tamano, mayor ID permitiria a T. digitalis una mejor habilidad para percibir la 3D y juzgar la distancia relativa entre los objetos, evitando asi combates competitivos y mejorando sus respuestas de escape y antidepredatorias. , Decapod metapopulation dynamics are better understood by confronting theoretical studies with empirical data. In this study, our goal was to analyse the morphometric characteristics and relative growth of the carapace of Trapezia bidentata (Forskal, 1775) and T. digitalis Latreille, 1828, crabs from the islands Clipperton and Revillagigedo, in order to assess the degree of inter- and intraspecific similarity of the four insular populations. We examined 325 specimens and identified four species: T. bidentata (72.9% of total abundance), T. digitalis (23.1%), T. formosa Smith, 1869 (3.4%), and T. corallina Gerstaecker, 1857 (0.6%). Three carapace measurements were taken for each specimen: carapace width (CW), carapace length (CL), and interocular distance (ID). The variables CL and ID were fit to a power equation taking CW as the reference dimension. As in other brachyurans, growth pattern analyses indicated an isometric type in all CW vs CL and CW vs ID relationships examined. Interspecific differences included a larger body size for T. bidentata and larger ID/CW for T. digitalis . Significant intraspecific differences in the two insular populations of T. digitalis were evidenced in the ID/CW ratio. In contrast, populations of T. bidentata were morphometrically closer. These results indicate a higher degree of connectedness of the parts of the T. bidentata metapopulation than of that of T. digitalis , probably due to differences in the duration of their larval stages. We think that the larger body size in T. bidentata might account for competitive advantages in food gathering and habitat selection over the remaining species. In turn, as a counteracting trait for its smaller size, the larger ID might allow T. digitalis a better ability to perceive 3D and to judge relative distances between objects, thus avoiding competitive combats and improving antipredatory or escape responses. La dinamica de las metapoblaciones de decapodos se comprende mejor confrontando estudios teoricos con datos empiricos. En este estudio, nuestro objetivo fue analizar las caracteristicas morfometricas y el crecimiento relativo del caparazon de Trapezia bidentata (Forskal, 1775) y T. digitalis Latreille, 1828, cangrejos de las islas Clipperton y Revillagigedo a fin de determinar el grado de similitud inter- e intraespecifica de las cuatro poblaciones insulares. Se examinaron 325 especimenes e identificaron cuatro especies: T. bidentata (72.9% de la abundancia total), T. digitalis (23.1%), T. formosa Smith, 1869 (3.4%) y T. corallina Gerstaecker, 1857 (0.6%). Para cada especimen, se tomaron tres dimensiones del caparazon: ancho (CW), largo (CL) y distancia interocular (ID). Las variables CL e ID se ajustaron a una ecuacion de tipo potencial tomando CW como la dimension de referencia. Como en otros braquiuros, los analisis del patron de crecimiento mostraron un tipo isometrico en todas las relaciones CW vs CL y CW vs ID examinadas. Las diferencias interespecificas incluyeron un mayor tamano corporal para T. bidentata y un mayor valor en el cociente ID/CW para T. digitalis . Se evidenciaron diferencias significativas intraespecificas entre las dos poblaciones insulares de T. digitalis en el cociente ID/CW. En contraste, las poblaciones de T. bidentata fueron morfometricamente mas semejantes. Estos resultados indican un mayor grado de conectividad en la metapoblacion de T. bidentata que en aquella de T. digitalis , debido probablemente a diferencias en la duracion de sus estados larvarios. Se piensa que la mayor talla corporal de T. bidentata representaria una mayor ventaja competitiva sobre el resto de las especies para atrapar alimento y seleccionar su habitat. A su vez, para contrarrestar su pequeno tamano, mayor ID permitiria a T. digitalis una mejor habilidad para percibir la 3D y juzgar la distancia relativa entre los objetos, evitando asi combates competitivos y mejorando sus respuestas de escape y antidepredatorias. ]

Geographical patterns in species richness of the benthic polychaetes in the continental shelf of the Gulf of California, Mexican Pacific

The present study is the first attempt to describe meso-scale patterns in the species richness of polychaetes along the Gulf of California, which stretches from about 23°N to 31°N. We examine herein the spatial changes in species distribution and explore the overlapping of species’ ranges towards the centre of the Gulf, to test whether the mid-domain effect (MDE) could explain an expected mid-domain peak in species richness. The faunal composition and the latitudinal range of 244 species of polychaetes recorded along the continental shelf of the Gulf of California were analysed in latitude bands of 1°. The species composition changes around the Gulf’s archipelago (~29°N), and the highest values of species richness are found at the 25° (197 species) and 26° (193 species) of latitude. Although the species richness pattern could be described by a parabolic shape, the regional trend was not strongly consistent with the peak of diversity at 27°N (176–191 species) predicted by the mid-domain effect: the random sorting of species’ ranges within spatial domain does not explain satisfactorily the geographical patterns of diversity. Nevertheless, a partial contribution of MDE to these natural patterns of diversity could be detected, and the increase in species richness towards middle latitudes was basically determined by species with distribution ranges larger than 6°. The low level of significance between the empirical species richness pattern and the mid-domain model prediction for polychaetes in the Gulf does not restrict their use as a model for exploring the randomness of the diversity patterns.

Eusyllinae, Exogoninae and Autolytinae (Syllidae: Polychaeta) from the Southern Mexican Pacific, with the description of three new species.

Previous studies have dealt recently with syllid polychaetes in soft sediments from Acapulco Bay (Southern Mexican Pacific) with new species and new records of the subfamily Syllinae published, but the remaining subfamilies found in the area had not been included. This study deals with syllids belonging to those subfamilies: Eusyllinae, Exogoninae and Autolytinae, since the Anoplosyllinae were not found. Three species are described as new: Odontosyllis septemdentata n. sp., characterized by having bidentate falcigers and a trepan with 7 teeth alternating in size; Sphaerosyllis tetralobata n. sp., which is characterized by having unidentate compound chaetae and segments divided in four annuli, and Prosphaerosyllis sotoi n. sp., characterized by having compound chaetae with short and hooked unidentate blades, and by being the only species of the genus that lacks dorsal cirri in the second parapodia. Additionally, Westheidesyllis gesae (Perkins 1981) is newly recorded for the Pacific Ocean, while Odontosyllis fulgurans (Audouin & Milne Edwards 1834), Erinaceusyllis bidentata (Hartmann-Schröder 1974) and Myrianida dentalia (Imajima 1966) are recorded for the first time from the Mexican Pacific coasts.

Description of two new species of Pisione (Polychaeta: Sigalionidae) and first record of Pisione galapagoensis Westheide in the Southern Mexican Pacific.

The genus Pisione Grube 1857 was composed up to now of 40 species and 4 subspecies. Although distributed worldwide, in the Mexican Pacific little is known about its taxonomy and distribution, and only two species of this genus have been recorded: Pisione longispinulata Aguado & San Martín, 2004 and Pisione remota (Southern, 1914), but the records of the latter remain questionable. For this study, 406 pisionids from soft sediments of Acapulco Bay, Southern Mexican Pacific, were examined. Two new species are described: Pisione hippocampus n. sp. characterized by having protruding notoaciculae in posterior chaetigers, the second dorsal cirrus elongated and copulatory organs resembling the body shape of a seahorse and Pisione sanmartini n. sp. characterized by having protruding notoaciculae from the first chaetiger, buccal aciculae with a distal crenulate plate resembling the edge of a shell, and prechaetal bifurcated lobes along the body. Pisione galapagoensis Westheide, 1974 is newly recorded for the Mexican Pacific, its known distribution being extended northward from the Galapagos Islands and Panama. A comparative table with the main diagnostic characters and the distribution of all the species so far described in the genus Pisione is included, as well as a key to the species of the Eastern Pacific.