Earliest known ophiuroids from high palaeolatitude, southern Gondwana, recovered from the Pragian to earliest Emsian Baviaanskloof Formation (Table Mountain Group, Cape Supergroup) South Africa.

For the first time, ophiuroids have been found in South African strata predating the lowermost Bokkeveld Group. These comprise natural moulds and casts from two localities in the 'upper unit' of the Baviaanskloof Formation (Table Mountain Group). As a Pragian to earliest Emsian age has been inferred for this member, the new taxa comprise the earliest high-palaeolatitude ophiuroid records from southern Gondwana. Morphological analysis of the specimens revealed the presence of two distinct taxa. One is here described as Krommaster spinosus gen. et sp. nov., a new encrinasterid characterised by very large spines on the dorsal side of the disc, the ventral interradial marginal plates and the arm midlines. The second taxon is a poorly preserved specimen of Hexuraster weitzi, a cheiropterasterid previously described from the slightly younger Bokkeveld Group.

Continent-wide declines in shallow reef life over a decade of ocean warming.

Human society is dependent on nature1,2, but whether our ecological foundations are at risk remains unknown in the absence of systematic monitoring of species' populations3. Knowledge of species fluctuations is particularly inadequate in the marine realm4. Here we assess the population trends of 1,057 common shallow reef species from multiple phyla at 1,636 sites around Australia over the past decade. Most populations decreased over this period, including many tropical fishes, temperate invertebrates (particularly echinoderms) and southwestern Australian macroalgae, whereas coral populations remained relatively stable. Population declines typically followed heatwave years, when local water temperatures were more than 0.5 °C above temperatures in 2008. Following heatwaves5,6, species abundances generally tended to decline near warm range edges, and increase near cool range edges. More than 30% of shallow invertebrate species in cool latitudes exhibited high extinction risk, with rapidly declining populations trapped by deep ocean barriers, preventing poleward retreat as temperatures rise. Greater conservation effort is needed to safeguard temperate marine ecosystems, which are disproportionately threatened and include species with deep evolutionary roots. Fundamental among such efforts, and broader societal needs to efficiently adapt to interacting anthropogenic and natural pressures, is greatly expanded monitoring of species' population trends7,8.

Miniaturization during a Silurian environmental crisis generated the modern brittle star body plan.

Pivotal anatomical innovations often seem to appear by chance when viewed through the lens of the fossil record. As a consequence, specific driving forces behind the origination of major organismal clades generally remain speculative. Here, we present a rare exception to this axiom by constraining the appearance of a diverse animal group (the living Ophiuroidea) to a single speciation event rather than hypothetical ancestors. Fossils belonging to a new pair of temporally consecutive species of brittle stars (Ophiopetagno paicei gen. et sp. nov. and Muldaster haakei gen. et sp. nov.) from the Silurian (444-419 Mya) of Sweden reveal a process of miniaturization that temporally coincides with a global extinction and environmental perturbation known as the Mulde Event. The reduction in size from O. paicei to M. haakei forced a structural simplification of the ophiuroid skeleton through ontogenetic retention of juvenile traits, thereby generating the modern brittle star bauplan.

Echinobase: leveraging an extant model organism database to build a knowledgebase supporting research on the genomics and biology of echinoderms.

Echinobase (www.echinobase.org) is a third generation web resource supporting genomic research on echinoderms. The new version was built by cloning the mature Xenopus model organism knowledgebase, Xenbase, refactoring data ingestion pipelines and modifying the user interface to adapt to multispecies echinoderm content. This approach leveraged over 15 years of previous database and web application development to generate a new fully featured informatics resource in a single year. In addition to the software stack, Echinobase uses the private cloud and physical hosts that support Xenbase. Echinobase currently supports six echinoderm species, focused on those used for genomics, developmental biology and gene regulatory network analyses. Over 38 000 gene pages, 18 000 publications, new improved genome assemblies, JBrowse genome browser and BLAST + services are available and supported by the development of a new echinoderm anatomical ontology, uniformly applied formal gene nomenclature, and consistent orthology predictions. A novel feature of Echinobase is integrating support for multiple, disparate species. New genomes from the diverse echinoderm phylum will be added and supported as data becomes available. The common code development design of the integrated knowledgebases ensures parallel improvements as each resource evolves. This approach is widely applicable for developing new model organism informatics resources.

Catalogue of living crinoids (Echinodermata: Crinoidea) from Brazil.

Knowledge of living crinoids from Brazil is chiefly restricted to the contributions of Dr Luis Roberto Tommasi between the decades of 1950 and 1970. Herein we present an updated catalogue of the crinoids occurring along the Brazilian coast, including data on synonyms, type localities, type material, geographical distribution, bathymetric ranges, and occurrences of species along the coast. The data is based on an extensive revision of the literature and on a survey of several databases. A total of 20 species were catalogued, of which two are endemic (Phrixometra longipinna var. brasiliensis and Thaumatometra minutissima). According to information from the literature, P. longipinna var. brasiliensis represents an undescribed taxon. Although Brazil supports the greatest number of crinoid species in the Southwestern Atlantic, its crinoid fauna remains understudied and likely underestimated. Research on crinoids remains a subject of great potential, not only for taxonomy but also for other areas of knowledge.

Deep-sea Ophiuroidea (Echinodermata) from the Danish Galathea II Expedition, 1950-52, with taxonomic revisions.

The brittle star samples collected by the Danish cruise 'Galathea II' (1950-52) had not been studied completely. We examined the remaining deep-sea samples (400 m) and present the species inventory, discussing taxonomic issues in relation to recent phylogenetic data. About 235 samples were examined, over 9,300 individuals, from 67 species and 74 sampling localities, at depths of 425-5340 m. The species complex Amphiophiura bullata (Thomson, 1877) is morphologically not well separated, but molecular data suggest at least two clades. We propose to apply A. bullata for Atlantic and Australian populations and A. convexa (Lyman, 1878) for the North Pacific clade. We consider A. bullata pacifica Litvinova, 1971 conspecific with A. convexa. Ophiuroglypha irrorata (Lyman, 1878) and its subspecies are a polyphyletic group with unclear morphological boundaries. We propose to transfer Ophiura ossiculata (Koehler, 1908), Ophiura plana (Lütken Mortensen, 1899) and Ophiura scomba Paterson, 1985 to Ophiuroglypha. Silax Fell, 1962, until now synonymised with Amphioplus Verrill, 1899, is proposed as a valid genus with the species S. verrilli (Lyman, 1879), S. consors (Koehler, 1908), S. daleus (Lyman, 1879), S. patulus (Lyman, 1879) and S. magnificus (Koehler, 1907). Triplodia Turner Hallen, 2011 (a replacement name for Triodia A. M. Clark, 1970, due to homonymy) is synonymised with Silax, and possible specimens of its type species Triodia abdita A. M. Clark, 1970 are analysed. The species limits of Ophiacantha cosmica Lyman, 1879 and Ophiacantha pacifica Lütken Mortensen, 1899 could not be confirmed morphologically, but published molecular data suggest two clades. We propose to apply O. pacifica to the Northern/Central Pacific population and O. cosmica to the Southern Pacific/Antarctic population.

A diverse crinoid fauna (Echinodermata, Crinoidea) from the Lower Eocene of the Gulf of Languedoc (Corbières, Aude, southern France).

Detailed studies of the middle Ilerdian (lower Ypresian) blue marls of the Gulf of Languedoc (Corbières, Aude, France), belonging to the north Pyrenean foreland basin, have revealed a more abundant and diverse crinoid fauna than previously documented from the Lower Eocene. Here we describe five species of stalked crinoids in the family Rhizocrinidae (Cherbonniericrinus requiensis n. sp., ?Democrinus elongatus, Globulocrinus amphoraformis n. gen., n. sp., Pseudoconocrinus doncieuxi and P. lavadensis n. sp.), one barnacle-like species in the stalkless family Holopodidae (Holopus plaziati n. sp.) and a single feather star in the family Conometridae (Amphorometra atacica). Several sites have yielded brachials and rhizoids in addition to abundant aboral cups and columnals indicating in situ fossilisation of the dissociated skeletal elements. P. lavadensis n. sp. and ?D. elongatus have been collected only from outcrops located in the upper part of the middle blue marls, while P. doncieuxi predominates, with a wide range of morphological variation, in the lower blue marls. The fossil assemblage at the locality of Réqui near Montlaur differs from the others in the smaller size of most individuals and the presence of H. plaziati n. sp., C. requiensis n. sp., G. amphoraformis n. gen., n. sp., and P. doncieuxi suboblongus n. subsp. This particular association with high juvenile mortality corresponds to an unstable environment with mixed substrates (muddy and rocky). The crinoid fauna of the Corbières appears to be the most diverse of Early Eocene age known to date. With the fauna of the London Clay, a boreal formation of the same age, it shares the presence of the genera Democrinus and Amphorometra in an open-sea environment. A comparison with extant faunas allows the depth of deposition at the Ypresian sites in the Gulf of Languedoc to be estimated between from 100 and 140 meters.

Taxonomy of the sea stars (Echinodermata: Asteroidea) from Bahia State, including ontogenetic variation and an illustrated key to the Brazilian species.

Describing ontogenetic morphological change is an important part of integrative taxonomy; still, most taxonomic studies are based only on adult characters. Here, we provide illustrations and a morphological description of the sea stars from Bahia, including ontogenetic and intraspecific variation, and identify taxonomic issues. A total of 293 specimens from different localities along the Bahia State coastline and comparative material from other localities were examined. Eighteen species (11 genera, eight families) of Asteroidea were identified; Astropectinidae was the most representative family. All species identified also occur in subtropical Brazilian waters and most species are from shallow water habitats with soft bottoms. Most observed ontogenetic variation was quantitative in nature, such as the increase in the number of spines in the furrow and of spinelets in the paxillae with specimen growth. Genera that require further taxonomic studies are Astropecten and Othilia, whose specimens are commonly misidentified in local studies. One third of the species from Bahia are currently classified as "Vulnerable" in the Brazilian Red List, but baseline data on the population biology of these species are scarce. An illustrated identification key to the 65 Brazilian sea star species is also provided. This taxonomic study will facilitate the identification of specimens occurring along the Brazilian coast and help scientists and policy makers to establish the conservation status of the Brazilian species.

Expansion of the genus Massinium (Holothuroidea: Thyonidae) to the American continent and description of a new species / Expansión del género Massinium (Holothuroidea: Thyonidae) al continente americano y descripción de una nueva especie

Introduction: The genus Massinium includes 11 species, most from the Indo Pacific Ocean, and had not previously being reported from the American continent. Objective: To present the new record of the genus Massinium and describe a new species of this genus. Methods: Material collection was done by SCUBA-diving to depths of a maximum of 9 m. Results: Massinium ocumichoensis sp. nov. is described from seven specimens that extends the range of the genus to the American continent (Guerrero, Michoacan and Jalisco, Mexico). The new species lives in sandy-rocky substrata, from 2 to 16 m deep. It is distinguished from its congeneric species by a combination of morphological characters: mid-dorsal slightly bigger pseudobuttons (40-60 μm), and tables in the body wall. A taxonomic key for distinguishing the species of Massinium is provided. Conclusions: The geographic range of the genus Massinium is extended to the Mexican Pacific with M. ocumichoensis sp. nov.

Introducción : El género Massinium incluye 11 especies, la mayoría del Océano Indo-Pacífico, y no se había reportado previamente en el continente americano. Objetivo: Presentar el nuevo registro del género Massinium y describir una nueva especie de este. Métodos: La recolección de material se realizó mediante buceo a una profundidad máxima de 9 m. Resultados: Massinium ocumichoensis sp. nov. se describe a partir de siete ejemplares que extiende el rango de distribución del género al Continente Americano (Guerrero, Michoacán y Jalisco, México). La nueva especie vive en sustratos arenosos-rocosos, de 2 a 16 m de profundidad. Se distingue de sus especies congenéricas por una combinación de caracteres morfológicos: pseudobotones de la zona dorsal media ligeramente más grandes (40-60 μm) y tablas en la pared del cuerpo. Se proporciona una clave taxonómica para distinguir las especies de Massinium. Conclusiones: El rango geográfico del género Massinium se extiende al Pacífico mexicano con M. ocumichoensis sp. nov.

Los ofiuroideos (Echinodermata: Ophiuroidea) de la bahía de Chamela, Jalisco, México / Ophiuroids (Echinodermata: Ophiuroidea) from Chamela bay, Jalisco, Mexico

Introducción: La bahía de Chamela está ubicada en la parte central de la costa del estado de Jalisco, México y es un importante área natural protegida. Pese a ello, el estudio de los equinodermos en la zona es incipiente. Objetivo: Proporcionar una lista de verificación actualizada, descripciones de las especies y una clave taxonómica de los ofiuroideos de la bahía de Chamela. Métodos: Recolectamos en la bahía de 1998 a 2018, y también analizamos información de la literatura y especímenes en colecciones científicas internacionales. Resultados: se reportan 19 especies de ofiuroides para el área de estudio, distribuidas en dos órdenes, siete familias y 11 géneros. Ocho de estos corresponden a nuevos registros para el área y tres posiblemente representan nuevas especies. La biodiversidad de ofiuroideos en la bahía de Chamela representa el 15.2% de las especies de ofiuroides del Pacífico mexicano y el 73% de Jalisco. El número de equinodermos conocidos en la bahía de Chamela aumenta a 48 especies. Conclusiones: Se presenta el listado más completo de la clase Ophiuroidea en la bahía de Chamela, Jalisco. La información proporcionada se puede utilizar para otras áreas del Pacífico oriental. La bahía de Chamela es importante en términos de riqueza de especies debido a su heterogeneidad ambiental y numerosas islas.

Introduction: Chamela bay is located in the central portion of the coast from the Jalisco state, Mexico and is an important protected natural area. Despite this, the study of echinoderms in the area is incipient. Objective: To provide an updated checklist, descriptions of the species and a taxonomic key of the ophiuroids from Chamela bay. Methods: We collected specimens from 1998 to 2018, and also analyzed information from the literature and specimens deposited at international scientific collections from Chamela bay. Results: 19 species of ophiuroids are reported for the study area, distributed in two orders, seven families, and 11 genera. Seven of these correspond to new records for the area, one to a new record for Jalisco state, and two possibly represent new species. The biodiversity of ophiuroids in Chamela bay represents 15.2 % of ophiuroid species from the Mexican Pacific and 73 % from Jalisco. The number of known echinoderms in Chamela bay is increased to 48 species. Conclusions: The most complete checklist of the class Ophiuroidea in Chamela bay, Jalisco, is presented. The information provided can be used for other areas of the eastern Pacific. Chamela bay is important in terms of species richness due to its environmental heterogeneity and numerous islands.

Equinodermos de Isla La Roqueta de Acapulco, Guerrero, México / Echinoderms from La Roqueta Island in Acapulco, Guerrero, México

Introducción: Guerrero es el cuarto Estado más biodiverso en México, ejemplo de ello, es la riqueza de equinodermos habitantes en sus costas, alberga el mayor número de especies en comparación con los estados del Pacífico Sur Mexicano, presenta 135 especies, mientras que Oaxaca 94 y Chiapas 15. El presente estudio se desarrolló en isla La Roqueta en Acapulco, Guerrero, México, es parte del 0.3 % del territorio nacional. Las islas son el hábitat de mayor número de especies y de endemismos, comparadas con áreas continentales de igual dimensión, isla La Roqueta, como otras islas en México, son reconocidas como sitios de gran valor, sin embargo, enfrentan graves amenazas que ponen en riesgo su estabilidad. Objetivo: Enlistar las especies de equinodermos en isla La Roqueta de Acapulco, Guerrero, México. Métodos: Se realizaron recolectas en agosto y octubre 2018 y mayo 2019, mediante buceo libre y Scuba en cuatro sitios, usando técnicas de captura directa, búsqueda de barrido, aleatorio y transecto. Resultados: 214 ejemplares fueron recolectados, en cuatro clases, nueve órdenes, 16 familias y 23 géneros, para un total de 40 especies. Se reconocen registros importantes: Ophiocoma sp., Phataria sp., Pentaceraster sp., Cucumaria sp., Astropyga sp., Meoma sp., Diadema sp., Afrocucumis ovulum, Pseudocnus californicus, Neocucumis veleronis y Holothuria imitans. Además, se destacan nuevos registros para el estado. Conclusiones: La complejidad de los diversos ambientes y sustratos marinos en Guerrero, en particular de isla La Roqueta, denota la posibilidad de nuevas especies.

Introduction: Guerrero is the fourth most biodiverse state in Mexico, an example of this is the wealth of echinoderms that inhabit its coasts, it houses the largest number of species compared to the states of the Mexican South Pacific, it has 135 species, while Oaxaca 94 and Chiapas 15. The present study was developed on La Roqueta Island in Acapulco, Guerrero, Mexico, it is part of 0.3% of the national territory. The islands are the habitat of a greater number of species and endemisms, compared to continental areas of the same size, isla La Roqueta, like other islands in Mexico, are recognized as sites of great value, however, they face serious threats that put their stability at risk. Objective: To list the species of echinoderms on the island of La Roqueta de Acapulco, Guerrero, México. Methods: We collected in August and October 2018 and May 2019, through free diving and Scuba, at four sites, using direct capture, sweep search, random and transect techniques. Results: 214 specimens were collected, in four classes, nine orders, 16 families and 23 genera, for a total of 40 species. Important records are recognized: Ophiocoma sp., Phataria sp., Pentaceraster sp., Cucumaria sp., Astropyga sp., Meoma sp., Diadema sp., Afrocucumis ovulum, Pseudocnus californicus, Neocucumis veleronis and Holothuria imitans. Conclusions: The complexity of the various marine environments and substrates in Guerrero, particularly on La Roqueta Island, denotes the possibility of new species.

Los equinodermos de El Salvador depositados en colecciones científicas / Echinoderms from El Salvador deposited at scientific collections

Introducción: El valor de las colecciones científicas radica en que los registros están vinculados directamente a especímenes físicos permitiendo conocer los avances en taxonomía, biogeografía e historia evolutiva de las especies. En El Salvador, las colecciones científicas están representadas en su mayoría por ejemplares de vertebrados terrestres y en menor proporción invertebrados marinos, en específico para el grupo de equinodermos su representación es escasa. Objetivo: Enlistar las colecciones científicas en las cuales se encuentran depositados ejemplares de equinodermos de El Salvador, conocer los esfuerzos realizados para la recolección de estos ejemplares y evaluar el aporte de las colecciones al conocimiento del taxón en el país. Métodos: Revisión de bases de datos abiertas de 18 colecciones extranjeras y nacionales; recopilando información biológica, número de ejemplares, sitio, año de recolecta y recolector. Resultados: Se encontraron 536 ejemplares en 192 registros de equinodermos depositados en seis colecciones científicas, nacionales y extranjeras, clasificadas en 40 especies, una de ellas nueva para El Salvador: Ophionereis perplexa. El National Museum of Natural History Smithsonian y el Instituto de Ciencias del Mar y Limnología de la Universidad de El Salvador albergan el mayor número de ejemplares, el primero con los ejemplares más antiguos, con más recolectas en La Unión y Sonsonate para ambas colecciones. Conclusiones: La representación de ejemplares en colecciones científicas nacionales y extranjeras es aceptable, registrando en los depósitos el 66.7 % del total reportado para El Salvador. Se recomienda continuar los esfuerzos en la identificación y catalogación de especies de aguas someras e iniciar las investigaciones con el taxón en aguas profundas.

Introduction: The value of scientific collections lies in the fact that the records are directly linked to real physical specimens allowing us to learn the advances in taxonomy, biogeography and evolutionary history of the species. In El Salvador, the scientific collections are represented mostly by specimens of terrestrial vertebrates and, to a lesser proportion, marine invertebrates, specifically for the group of echinoderms their representation is scarce. Objective: To enlist the scientific collections in which echinoderm specimens of El Salvador are deposited, to know about the efforts made to collect these specimens and evaluate the contribution of the collections to the knowledge of the taxon in the country. Methods: Review of open databases of 18 foreign and national collections; collecting biological information, number of specimens, site, year of collection and collector. Results: 536 specimens were found in 192 records of echinoderms deposited in six scientific collections, national and foreign, classified into 40 species, one of them new for El Salvador: Ophionereis perplexa. The National Museum of Natural History (Smithsonian) and the Institute of Marine Sciences and Limnology of the University of El Salvador have the largest number of specimens (Smithsonian has the oldest specimens). Conclusions: The representation of specimens in national and foreign scientific collections is acceptable, with 67 % of the total reported for El Salvador. We recommend continuation of work in shallow-waters and start of deep-water study.

Morphological variability of recent species of the order Cassiduloida (Echinodermata: Echinoidea) of Mexico / Variabilidad morfológica de especies recientes del orden Cassiduloida (Echinodermata: Echinoidea) de México

Introduction: In Mexico, there are two recorded living species of Cassiduloida: Cassidulus caribaearum and Rhyncholampas pacifica. Most of the taxonomic studies on cassiduloids have used external morphology, pedicellariae and morphometric characters; however, the intraspecific variation of quantitative and qualitative characters has been poorly evaluated. Objective: To compare the basic morphology of R. pacifica and C. caribaearum. Methods: We examined a total of 2 158 specimens of R. pacifica and C. caribaearum, selecting 50 to evaluate shape and size with linear regression and Principal Component analysis. We selected an additional 62 specimens per species to identify significant character correlations and morphological groups within species. Results: There is a direct relationship between Test length and Test width. Test height/Test width, and Total length (oral view)/Distance from the ambitus to the peristome apex, are the two main ratios to distinguish both species. C. caribaearum is more dorsoventrally compressed and has a round peristome base; versus R. pacifica has a tall and triangular one. There are four morphological groups of C. caribaearum and two groups for R. pacifica. Conclusions: These two species can be distinguished with reliable morphological characters, in which peristome shape suggests that R. pacifica is more adapted to burrowing deeper into certain types of substratum.

Introducción: En México, hay dos especies vivientes registradas de Cassiduloida: Cassidulus caribaearum y Rhyncholampas pacifica. La mayoría de los estudios taxonómicos sobre casiduloides han utilizado morfología externa, pedicelarios y caracteres morfométricos; sin embargo, la variación intraespecífica de caracteres cuantitativos y cualitativos ha sido poco evaluada. Objetivo: Comparar la morfología básica de R. pacifica y C. caribaearum. Métodos: Examinamos un total de 2 158 especímenes de R. pacifica y C. caribaearum, seleccionando 50 para evaluar la forma y el tamaño con regresión lineal y análisis de componentes principales. Seleccionamos 62 especímenes adicionales por especie para identificar correlaciones significativas de caracteres y grupos morfológicos dentro de las especies. Resultados: Existe una relación directa entre la longitud de la testa y el ancho de la testa. La Altura de la testa / Anchura de la testa y la Longitud total (vista oral) / Distancia desde el ambitus hasta el ápice del peristoma, son las dos proporciones principales para distinguir ambas especies. C. caribaearum está más comprimido dorsoventralmente y tiene una base del peristoma redonda; versus R. pacifica que tenía una alta y triangular. Hay cuatro grupos morfológicos de C. caribaearum y dos grupos de R. pacifica. Conclusiones: Estas dos especies se pueden distinguir con caracteres morfológicos confiables, en los que la forma del peristoma sugiere que R. pacifica está más adaptada para excavar más profundamente en ciertos tipos de sustratos.

Echinoderms (Echinodermata) from the Central Mexican Pacific / Equinodermos (Echinodermata) del Pacífico Central mexicano

Introduction: The echinoderms from the Central Mexican Pacific are of high scientific interest and, prior to this present work, there was a lack of basic information that included incomplete checklists with inconsistencies in systematics and spatial distribution. Objective: To provide a historical review, and an updated checklist with a more complete richness of echinoderms for each state and island of the region. Methods: A checklist was elaborated based on an exhaustive literature search of the Echinodermata, and was complemented with taxonomical revisions of Ophiuroidea scientific collections. All the geographical coordinates of the records were validated. Results: The region harbors 187 species of Echinodermata: three Crinoidea, 35 Asteroidea, 67 Ophiuroidea, 32 Echinoidea, and 50 Holothuroidea. We detected 52 records in the literature that must be considered as invalid and five as doubtful. We provide 16 new records of Ophiuroidea from different states and islands; of them, four are new records for the region. Jalisco presented the highest number of species (84), followed by the coast of Nayarit (74), Michoacán (63), and Colima (55); among the islands, Revillagigedo showed the major number of species (85) followed by Marías (81), Marietas (48), and Isabel (44). Conclusions: The numbers of species known in the region are mostly related to both sampling effort and environmental characteristics that promote high biodiversity. The Central Mexican Pacific is an oceanographic region with mixed conditions from the North and South of the Mexican Pacific, and therefore, with a biogeographical importance reflected in its species richness.

Introducción: Los equinodermos del Pacífico Central mexicano poseen un alto interés científico, pero anterior al presente trabajo existía un vacío en la información básica como listados de especies incompletos con inconsistencias sistemáticas y de distribución espacial. Objetivo: Proporcionar una revisión histórica y un listado de especies actualizado con la riqueza completa de equinodermos para cada estado e islas de la región. Métodos: Se elaboró un listado de especies basado en una búsqueda exhaustiva de Echinodermata, y fue complementada con la revisión taxonómica de Ophiuroidea de colecciones científicas. Todas las coordenadas geográficas de los registros fueron validadas. Resultados: La región posee 187 especies de Echinodermata: tres Crinoidea, 35 Asteroidea, 67 Ophiuroidea, 32 Echinoidea, y 50 Holothuroidea. Detectamos 52 registros en la literatura considerados como inválidos y cinco como dudosos. Proveemos 16 nuevos registros de Ophiuroidea para diversos estados e islas; de estos, cuatro son nuevos registros para la región. Jalisco presentó el mayor número de especies (84), seguido por las costas de Nayarit (74), Michoacán (63), y Colima (55); entre las islas, Revillagigedo presentó el mayor número de especies (85) seguido por Marías (81), Marietas (48), e Isabel (44). Conclusiones: Los números de especies de la región están mayormente relacionados tanto con el esfuerzo de muestreo como con características ambientales que promueven una alta biodiversidad. El Pacífico Central mexicano es una región oceanográfica con condiciones mixtas del norte y sur del Pacífico mexicano, y por lo tanto con una importancia biogeográfica reflejada en la riqueza de la región.

Biodiversidad de ofiuroideos (Echinodermata: Ophiuroidea) del talud de la Península de Yucatán, México / Biodiversity of ophiuroids (Echinodermata: Ophiuroidea) from the slope of the Yucatan Peninsula, Mexico

Introduction: The Ophiuroidea class is the most diverse of the Phylum Echinodermata, with 2 064 described species, which can be found from intertidal zones to abyssal depths, but the fauna of Yucatan peninsula needs more study. Objective: To describe the diversity of ophiuroids in the Yucatan continental slope. Methods: Information was compiled from four oceanographic surveys carried out in August 2005, June 2007 (BIOREPES 1 and 2: BRP1 and BRP2), April 2011 and August 2014 (COBERPES 2 and 6: CBP2 and CBP6). The specimens were obtained by trawling with a shrimp net in soft substrates and with a skimmer-type trawl dredge at a depth range of 200 to 1 071 m off the states of Yucatán and Quintana Roo, Mexico. Results: We found members of two superorders, five orders, six suborders, five superfamilies, 18 families, 28 genera and 43 species. Conclusions: The northeast zone Yucatan Peninsula has at least 43 species, of which 19 are new records for the area.

Introducción: La clase Ophiuroidea es la más diversa del Phylum Echinodermata, con 2 064 especies descritas, que se pueden encontrar desde zonas intermareales hasta profundidades abisales, pero la fauna de la península de Yucatán necesita más estudio. Objetivo: Describir la diversidad de ofiuroideos en el talud continental de Yucatán. Métodos: Se recopiló información de cuatro estudios oceanográficos llevados a cabo en agosto de 2005, junio de 2007 (BIOREPES 1 y 2: BRP1 y BRP2), abril de 2011 y agosto de 2014 (COBERPES 2 y 6: CBP2 y CBP6). Los especímenes se obtuvieron mediante la pesca de arrastre con una red camaronera en sustratos blandos y con una draga de arrastre tipo skimmer en un rango de profundidad de 200 a 1 071 m frente a los estados de Yucatán y Quintana Roo, México. Resultados: Encontramos miembros de dos superórdenes, cinco órdenes, seis subórdenes, cinco superfamilias, 18 familias, 28 géneros y 43 especies. Conclusiones: La zona noreste de la Península de Yucatán tiene al menos 43 especies, de las cuales 19 son nuevos registros para el área.

Diversity and biostratigraphy of the late Oligocene-late Miocene sand dollars (Echinoidea: Scutelliformes) of Argentina and Uruguay / Diversidad y bioestratigrafía de las galletas de mar (Echinoidea: Scutelloida: Scutellifomes) del Oligoceno tardío-Mioceno tardío de Argentina y Uruguay

Introduction: Scutelliforms were diverse and widespread in shallow marine environments during Neogene times in South America. Nevertheless, they have almost never been used as biostratigraphic tools. Objective: To provide a refined stratigraphic frame useful for calibrating temporal dimensions of scutelliform diversity from Argentina and Uruguay and its correlation with the molluscan assemblages previously proposed. Methods: A detailed survey of their geographic and stratigraphic provenance was carried out. We revised both the bibliography and collections (institutional and from our own field work). Results: The group is represented by 14 species belonging to six genera, and four assemblages were identified. Numerical dates of the Neogene marine rocks obtained recently allowed their placement in a chronological scheme: "Iheringiella" sp. A is restricted to the late Oligocene, the genera Camachoaster and "Eoscutella" and the species Monophoraster telfordi to the early Miocene, Abertella gualichensis and Abertella miskellyi to the middle Miocene, and Monophoraster duboisi, Amplaster coloniensis and Amplaster ellipticus to the late Miocene. Non-lunulate scutelliforms are not restricted to the late Oligocene as previously supposed. The oldest occurrence of the genus Monophoraster corresponds to the early Miocene, and along with Iheringiella are long-living taxa that embrace the 25.3 Ma-18.1 Ma (Iheringiella patagonensis) and approximately 15 Ma-6.48 Ma (Monophoraster darwini) intervals. The presence of Iheringiella in the early Miocene of northeastern Patagonia is corroborated, reaching there its northernmost distribution. Monophoraster darwini has a temporal range from the late Miocene (where it was previously thought to be restricted) back to the middle Miocene, since this is the species yielded in the well-known and discussed "Monophoraster and Venericor Beds". Conclusions: The Paleogene-Neogene scutelliforms of Argentina and Uruguay range from the late Oligocene to the late Miocene. There is a good correspondence among the numerical ages, molluscan biozones and scutelliform assemblages.

Introducción: Realizamos una síntesis actualizada de la composición taxonómica de las asociaciones de escutélidos del Oligoceno tardío-Mioceno tardío de Argentina y Uruguay. Objetivo: Ubicar los escutélidos en un marco estratigráfico refinado, a los efectos de observar su diversidad a lo largo del tiempo y la correlación de sus ensambles con los ya conocidos de moluscos. Métodos: Revisamos en detalle la procedencia geográfica y estratigráfica de los ejemplares y su asignación taxonómica, basándonos tanto en la bibliografía como en colecciones institucionales y producto de nuestras campañas de colecta. Resultados: El grupo está representado por 14 especies agrupadas en seis géneros, siendo identificadas en cuatro ensambles. Las edades numéricas recientemente obtenidas permitieron su ubicación en un esquema cronológico: "Iheringiella" sp. A se restringe al Oligoceno tardío, Camachoaster y "Eoscutella", y Monophoraster telfordi al Mioceno temprano, Abertella gualichensis y Abertella miskellyi al Mioceno medio, y Monophoraster duboisi, Amplaster coloniensis y Amplaster ellipticus al Mioceno tardío. Los escutélidos sin lúnula no están restringidos al Oligoceno tardío como se suponía. Monophoraster aparece en el Mioceno temprano y junto con Iheringiella abarcan largos períodos de tiempo, encontrándoselos entre los 25.3 Ma-18.1 Ma (Iheringiella patagonensis) y aproximadamente los 15 Ma-6.48 Ma (Monophoraster darwini). Se corrobora la presencia de Iheringiella en el Mioceno temprano del noreste de Patagonia, donde alcanza su punto más septentrional. Monophoraster darwini se encuentra desde el Mioceno medio hasta el Mioceno tardío (lapso para el cual previamente se consideraba restringido), ya que se trata de la especie presente en los bien conocidos "estratos con Monophoraster y Venericor". Conclusiones: Los escutélidos del Paleógeno-Neógeno de Argentina y Uruguay se encuentran desde el Oligoceno tardío hasta el Mioceno tardío. Hay una buena correspondencia entre las edades numéricas, las biozonas de moluscos y los ensambles de escutélidos.

Annotated checklist for the Gorgonocephalidae family (Echinodermata: Ophiuroidea) from the National Echinoderm Collection "Dra. Ma. E. Caso M." of the Instituto de Ciencias del Mar y Limnología, UNAM / Lista anotada de la familia Gorgonocephalidae (Echinodermata: Ophiuroidea) de la Colección Nacional de Equinodermos "Dra. Ma. E. Caso M." del Instituto de Ciencias del Mar y Limnología, UNAM

Introduction: The order Euryalida is represented by fragile ophiuroids with long and slender arms that can be ramified. Species within the family Gorgonocephalidae are characterized by the presence of tiny hooklets on the dorsal aspect of their arms. There are very few published studies referring to species of the family Gorgonocephalidae inhabiting Mexican waters. Objective: To review the taxonomic status of the species belonging to this taxonomic family, identifying their diagnostic taxonomic characteristics to create an illustrated guide of species kept at the CNE, UNAM. Methods: Specialized bibliography of the Gorgonocephalidae family was gathered. Subsequently, all the specimens from the CNE were photographed using Scanning Electron and Multifocal Microscopy photography, to show the structures of taxonomic relevance. Results: A total of 193 specimens corresponding to eight genera and nine species were reviewed. The genus Astrocaneum presented the highest species richness. Conclusions: For the species identified in this study and for the sake of accurate identification, morphological characters such as the shape of hooklets and arm plates were highlighted.

Introducción: El orden Euryalida está formado por ofiuros frágiles con brazos delgados, largos y a veces ramificados. Las especies de la familia Gorgonocephalidae se caracterizan por la presencia de diminutos ganchos en el lado dorsal de sus brazos. Los estudios que refieren especies de la familia Gorgonocephalidae que habitan en aguas mexicanas son escasos. Objetivo: Realizar la revisión taxonómica de dicha familia, reconociendo los caracteres taxonómicos diagnósticos para generar una guía ilustrada de cada una de las especies que se encuentran en la CNE del ICML, UNAM. Métodos: Se recopiló toda la bibliografía especializada de la familia, posteriormente con ayuda de fotografías de MEB y multifocal se fotografiaron los especímenes de la CNE para destacar las estructuras de importancia taxonómica. Resultados: se revisaron un total de 193 ejemplares correspondientes a ocho géneros, nueve especies, siendo el género Astrocaneum el de mayor riqueza específica. Conclusiones: Para las especies identificadas en este estudio, para dar una identificación más precisa, se destacaron los caracteres morfológicos forma de los ganchos y forma de las placas de los brazos.

Molecular and functional characterization of somatostatin-type signalling in a deuterostome invertebrate.

Somatostatin (SS) and allatostatin-C (ASTC) are structurally and evolutionarily related neuropeptides that act as inhibitory regulators of physiological processes in mammals and insects, respectively. Here, we report the first molecular and functional characterization of SS/ASTC-type signalling in a deuterostome invertebrate-the starfish Asterias rubens (phylum Echinodermata). Two SS/ASTC-type precursors were identified in A. rubens (ArSSP1 and ArSSP2) and the structures of neuropeptides derived from these proteins (ArSS1 and ArSS2) were analysed using mass spectrometry. Pharmacological characterization of three cloned A. rubens SS/ASTC-type receptors (ArSSR1-3) revealed that ArSS2, but not ArSS1, acts as a ligand for all three receptors. Analysis of ArSS2 expression in A. rubens using mRNA in situ hybridization and immunohistochemistry revealed stained cells/fibres in the central nervous system, the digestive system (e.g. cardiac stomach) and the body wall and its appendages (e.g. tube feet). Furthermore, in vitro pharmacological tests revealed that ArSS2 causes dose-dependent relaxation of tube foot and cardiac stomach preparations, while injection of ArSS2 in vivo causes partial eversion of the cardiac stomach. Our findings provide new insights into the molecular evolution of SS/ASTC-type signalling in the animal kingdom and reveal an ancient role of SS-type neuropeptides as inhibitory regulators of muscle contractility.

Aproximación morfológica y molecular al conocimiento de las ofiuras (Echinodermata: Ophiuroidea) en el Parque Nacional Marino Las Baulas (Pacífico Norte, Costa Rica) / Morphological and molecular approaches to the study of ophiuroids (Echinodermata: Ophiuroidea) at Las Baulas Marine National Park (North Pacific, Costa Rica)

Introducción: El conocimiento de la Clase Ophiuroidea es muy escaso y deficiente, a pesar de ser la que presenta el mayor número de especies del Filo Echinodermata con hasta 2 100. Además, apenas existen publicaciones dedicadas específicamente al grupo de las ofiuras en la vertiente pacífica de Costa Rica. Objetivo: La caracterización morfológica y genética de las ofiuras de la franja intermareal y sublitoral somero del Parque Nacional Marino Las Baulas (Pacífico de Costa Rica). Métodos: El periodo de recolecta se extendió entre enero y abril de 2018 y tuvo lugar a lo largo de siete localidades: Punta del Morro, Playa Carbón, Playa Ventanas, Playa Grande, Playa Tamarindo Ciudad, Playa Tamarindo y Playa Langosta. Se ha realizado la caracterización de 214 ofiuras mediante claves taxonómicas, descripciones originales y el marcador mitocondrial citocromo c oxidasa subunidad I (COI). Resultados: En total, combinando los caracteres morfológicos y genéticos, se han identificado 11 especies, cuatro de las cuales podrían ser nuevas, nueve constituyen nuevos registros en el parque y una de las especies se ha encontrado por primera vez en Costa Rica (Ophiophragmus aff. stellatus). Además, se han identificado individuos juveniles y se han encontrado dos especies crípticas. Conclusión: Del estudio molecular se concluye que el marcador COI es útil para delimitar molecularmente las especies y establecer relaciones filogenéticas para los niveles taxonómicos de género y especie, pero no para los superiores. Se aportan observaciones morfológicas e imágenes como contribución a la taxonomía del grupo.

Introduction: Information on the class Ophiuroidea is very scarce, despite it consisting of the highest number of species within the phylum Echinodermata, with up to 2 100 species. In particular, there are hardly any study focused specifically to ophiuroids found along the Pacific coast of Costa Rica. Objective: Morphological and genetic characterization of ophiuroids of the shallow intertidal and sublittoral areas of Las Baulas Marine National Park (Pacific coast of Costa Rica). Methods: Sampling was conducted between January and April of 2018 at seven locations: Punta del Morro, Playa Carbón, Playa Ventanas, Playa Grande, Playa Tamarindo Ciudad, Playa Tamarindo and Playa Langosta. A total of 214 ophiuroids were characterized using taxonomic keys and original descriptions and a molecular analysis of the mitochondrial Cytochrome oxidase I (COI) gene. Results: An analysis of morphological and genetic characters indicates that 11 species are present in the study site. Four may represent new species, nine constitute new records for the area and one (Ophiophragmus aff. stellatus) is recorded in Costa Rica for the first time. Additionally, juvenile individuals of different species were identified, and two cryptic species were detected. Conclusions: According to the molecular analysis, COI is useful to delimit ophiuroid species and to establish phylogenetic relationships at lower (genera and species) but not higher taxonomic levels. This study also provides images and morphological remarks for future comparative studies.

Evolution and Development at the Origin of a Phylum.

Quantifying morphological evolution is key to determining the patterns and processes underlying the origin of phyla. We constructed a hierarchical morphological character matrix to characterize the radiation and establishment of echinoderm body plans during the early Paleozoic. This showed that subphylum-level clades diverged gradually through the Cambrian, and the distinctiveness of the resulting body plans was amplified by the extinction of transitional forms and obscured by convergent evolution during the Ordovician. Higher-order characters that define these body plans were not fixed at the origin of the phylum, countering hypotheses regarding developmental processes governing the early evolution of animals. Instead, these burdened characters were flexible, enabling continued evolutionary innovation throughout the clades' history.