The importance of molecular characters when morphological variability hinders diagnosability: systematics of the moon jellyfish genus Aurelia (Cnidaria: Scyphozoa)

Cryptic species have been detected across Metazoa, and while no apparent morphological features distinguish them, it should not impede taxonomists from formal descriptions. We accepted this challenge for the jellyfish genus Aurelia, which has a long and confusing taxonomic history. We demonstrate that morphological variability in Aurelia medusae overlaps across very distant geographic localities. Even though some morphological features seem responsible for most of the variation, regional geographic patterns of dissimilarities are lacking. This is further emphasized by morphological differences found when comparing lab-cultured Aurelia coerulea medusae with the diagnostic features in its recent redescription. Previous studies have also highlighted the difficulties in distinguishing Aurelia polyps and ephyrae, and their morphological plasticity. Therefore, mostly based on genetic data, we recognize 28 species of Aurelia, of which seven were already described, 10 are formally described herein, four are resurrected and seven remain undescribed. We present diagnostic genetic characters for all species and designate type materials for newly described and some resurrected species. Recognizing moon jellyfish diversity with formal names is vital for conservation efforts and other studies. This work clarifies the practical implications of molecular genetic data as diagnostic characters, and sheds light on the patterns and processes that generate crypsis.Fil: Lawley, Jonathan W.. Universidade de Sao Paulo; Brasil. Griffith University; AustraliaFil: Gamero Mora, Edgar. Universidade de Sao Paulo; BrasilFil: Maronna, Maximiliano Manuel. Universidade de Sao Paulo; BrasilFil: Chiaverano, Luciano Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: Stampar, Sérgio N.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Hopcroft, Russell R.. University of Alaska; Estados UnidosFil: Collins, Allen G.. National Museum of Natural History; Estados UnidosFil: Morandini, André C.. Universidade de Sao Paulo; Brasi

Morphology is not always useful for diagnosis, and that’s ok: Species hypotheses should not be bound to a class of data. Reply to Brown and Gibbons (S Afr J Sci. 2022;118(9/10), Art. #12590)

This paper serves as a reply to the Commentary by Brown and Gibbons (S Afr J Sci. 2022;118(9/10), Art. #12590) on our recently published paper on systematics of the moon jellyfish genus Aurelia (Lawley et al. PeerJ 2021;9, e11954)). We emphasise that we are not advocating for the routine use of molecular data alone in taxonomic diagnoses, rather that it is a valid approach in cases where, after detailed analyses, morphological features are shown to be unreliable

Morphological and molecular revision of the upside-down jellyfish Cassiopea Péron & Lesueur, 1810 (Cnidaria: Scyphozoa: Rhizostomeae)

As medusas do gênero Cassiopea Péron & Lesueur, 1810 estão amplamente distribuídas em habitats marinhos e estuarinos, tropicais e subtropicais, rasos; são os únicos membros de Kolpophorae com representantes no Atlântico Ocidental e no Indo-Pacífico. O status atual da diversidade de Cassiopea é incerto e pode estar subestimado pela (1) presença de espécies crípticas, (2) baixa representatividade geográfica na amostragem de trabalhos anteriores, (3) falta de estudos sistemáticos comparados direcionados ao grupo. Compreender a sistemática do gênero Cassiopea tem se tornado uma prioridade uma vez que espécies deste táxon tem ganhando terreno como organismos modelo nos últimos anos. Assim, este projeto foi elaborado para realizar uma revisão sistemática do gênero Cassiopea (que permitiria uma melhor compreensão da evolução, biogeografia e ecologia do grupo) utilizando dados moleculares e morfológicos. O 2o. capítulo \"Hidden diversity and insights into the origin and biogeography of the upside-down jellyfishes (Cnidaria: Scyphozoa)\" foi baseado em dados moleculares, e nos permitiu detectar uma divisão no nó mais profundo da filogenia entre as linhagens Atlântica e Indo-Pacífica. Além disso, foi revelada uma diversidade oculta no Indo-Pacífico. No total, foram delimitadas 17 espécies, as quais estão diagnosticadas por caracteres moleculares. Os resultados foram discutidos no contexto da riqueza de espécies e das relações de parentesco do grupo, sendo possível elucidar aspetos sobre sua origem e biogeografia. No 3o. capítulo \"Revision of the upside-down jellyfish genus Cassiopea Péron & Lesueur, 1810 (Cnidaria: Scyphozoa)\" encontramos que caracteres morfológicos derivados da observação dos braços orais, apêndices orais, ropálios e óstios subgenitais são úteis para delimitar algumas espécies. No entanto, a morfologia nem sempre é suficiente para a elucidação e delimitação de espécies, sendo necessário o uso de outras fontes de informação em alguns casos. Nossos resultados indicam que das 11 espécies nominais de Cassiopea oito foram consideradas válidas: C. frondosa, C. andromeda, C. mertensi, C. ornata, C. picta, C. xamachana, C. ndrosia, C. maremetens; sendo designados neótipos para seis delas. C, vanderhorsti foi considerada sinônimo de C. xamachana. Cassiopea depressa foi considerada species inquirenda. Cassiopea medusa foi considerada nomen dubium. Duas espécies novas são propostas e descritas: C. apendicula [Localidade-tipo: Subic Bay, Luzon Island, Philippines] e C. ongaeli [Localidade-tipo: Ongael Lake, Palau, Oceania]. No 4o. capítulo \"Regenerative Capacity of the Upside-down Jellyfish Cassiopea xamachana\" usamos abordagens morfológicas e moleculares para identificar a espécie e discutir um processo que foi observado no tecido umbrelar que pode levar à formação de praticamente todas as estruturas corporais em C. xamachanaJellyfishes of the genus Cassiopea Péron & Lesueur, 1810 are widely distributed throughout shallow tropical and subtropical marine and estuarine habitats, being the only members within Kolpophorae with representatives both in the Western Atlantic and the Indo- Pacific region. The present status of Cassiopea diversity is uncertain and could be underestimated by (1) cryptic forms that hampers the establishment of species boundaries, (2) poor collecting efforts, and (3) the lack of comparative systematics studies directed to this group. Understanding the systematics of the genus Cassiopea has become a priority because some species are gaining ground as model organisms. This project was designed to perform a revision of the genus Cassiopea (which would allow a better comprehension of the evolution, biogeography, and ecology of this group) under the light of molecular and morphological data. The 2nd chapter \"Hidden diversity and insights into the origin and biogeography of the upside-down jellyfishes (Cnidaria: Scyphozoa)\" based on molecular data let us to identify an early division into Atlantic and Indo-Pacific lineages. Also, it revealed a hidden diversity, in the Indo-Pacific region, allowing us to recognize and propose diagnostic molecular characters for 17 species. We discussed our findings in the context of the species richness and phylogenetic relationships within Cassiopea, to elucidate about its origin and biogeography. In the 3rd chapter \"Revision of the upside-down jellyfish genus Cassiopea Péron & Lesueur, 1810 (Cnidaria: Scyphozoa)\" our results indicate that morphological characters derived from the observation of the oral arms, oral appendages, sense organs, and subgenital pits are useful for delimiting some species. However, morphology was not always reliable to discover and establish limits between certain species, being necessary other sources of information to support species hypotheses. Taxonomic actions that followed our revision included: eight valid species: C. frondosa, C. andromeda, C. mertensi, C. ornata, C. picta, C. xamachana, C. ndrosia and C. maremetens. Cassiopea vanderhorsti is considered a synonym of C. xamachana. Cassiopea depressa is considered species inquirenda. Cassiopea medusa is considered nomen dubium. Two new species are proposed and described: C. appendicular [Type-locality: Subic Bay, Luzon Island, Philippines] e C. ongaeli [Type-locality: Ongael Lake, Palau, Oceania]. In the 4th chapter \"Regenerative Capacity of the Upside-down Jellyfish Cassiopea xamachana\", morphological and molecular approaches were used to identify the species and discuss a process in which we observed that the umbrellar tissue can lead to the formation of virtually all body structures in C. xamachan

Análisis de la comunidad del zooplancton gelatinoso (Hydrozoa, Ctenophora, Thaliacea) en el Pacífico central mexicano, abril-mayo 2011

The gelatinous zooplankton, an important functional group in the water column, was studied during April and May 2011 in Mexican waters of the Eastern Tropical Pacific. Zooplankton samples and environmental data were obtained during the MareaR-III cruise on board the R/V `El Puma' (Universidad Nacional Autónoma de México, UNAM). We identified 32 species of gelatinous zooplankton including 25 species of cnidarians (14 medusae, 11 siphonophores), 2 ctenophores and 5 thaliaceans. Up to 14 of these species represent new records for the surveyed area. The medusae Calycopsis simplex, Sphaerocoryne bedoti, Stauridiosarsia baukalion, Lovenella clausa and the siphonophore Sphaeronectes irregularis are recorded for the first time in Mexican waters. High occurrences and/or abundances of the thaliacean Dolioletta gegenbauri, Doliolum nationalis, the medusae Aglaura hemistoma, Liriope tetraphylla, Rhopalonema velatum, Cunina octonaria and the siphonophore Muggiaea atlantica were detected. Lowest diversity values were found in the northern and southern sectors of the surveyed area. The canonical correspondence analysis revealed that most species are related to environmental characteristics of the northern part of the surveyed area. The species richness and the abundance were highly influenced by the occurrence of trachy and narcomedusas in sampling stations both near as far from the shore line, as well as by the occurrence of doliolids. The high abundance of gelatinous zooplankton from oceanic waters throughout the surveyed area is attributed to the narrowness of the continental shelf.El zooplancton gelatinoso, un importante grupo funcional en la columna de agua, fue estudiado en aguas mexicanas del Pacífico tropical oriental durante abril y mayo de 2011. El material analizado se recolectó durante la campaña oceanográfica MareaR-III a bordo del B/O `El Puma' (Universidad Nacional Autónoma de México, UNAM). Se identificaron 32 especies de zooplancton gelatinoso, incluyendo 25 especies de cnidarios (14 medusas, 11 sifonóforos), 2 ctenóforos y 5 taliáceos; 14 son nuevos registros para el área de estudio. Se registran por primera vez en aguas mexicanas las medusas Calycopsis simplex, Sphaerocoryne bedoti, Stauridiosarsia baukalion, Lovenella clausa, y el sifonóforo Sphaeronectes irregularis. Destacan por su frecuencia y por su alta densidad los taliáceos Dolioletta gegenbauri, Doliolum nationalis, las medusas Aglaura hemistoma, Liriope tetraphylla, Rhopalonema velatum, Cunina octonaria y el sifonóforo Muggiaea atlantica. La diversidad de Shannon presentó sus valores menores en las zonas más septentrionales y meridionales. El análisis de correspondencia canónica reveló que la mayoría de las especies son afines a las características ambientales registradas en el sector norte del Pacífico central mexicano. Tanto la riqueza de especies como la densidad de organismos están determinadas por la presencia de narcomedusas y traquimedusas, así como por doliólidos. La alta densidad de seres del zooplancton gelatinoso de aguas oceánicas en toda la zona de estudio es favorecida por la estrechez de la plataforma continental en el Pacífico central mexicano

The puzzling occurrence of the upside-down jellyfish Cassiopea (Cnidaria: Scyphozoa) along the Brazilian coast: a result of several invasion events?

The massive occurrence of jellyfish in several areas of the world is reported annually, but most of the data come from the northern hemisphere and often refer to a restricted group of species that are not in the genus Cassiopea. This study records a massive, clonal and non-native population of Cassiopea and discusses the possible scenarios that resulted in the invasion of the Brazilian coast by these organisms. The results indicate that this jellyfish might have invaded the Brazilian coast multiple times

The puzzling occurrence of the upside-down jellyfish Cassiopea (Cnidaria: Scyphozoa) along the Brazilian coast: a result of several invasion events?

The massive occurrence of jellyfish in several areas of the world is reported annually, but most of the data come from the northern hemisphere and often refer to a restricted group of species that are not in the genus Cassiopea. This study records a massive, clonal and non-native population of Cassiopea and discusses the possible scenarios that resulted in the invasion of the Brazilian coast by these organisms. The results indicate that this jellyfish might have invaded the Brazilian coast multiple times

Morphology is not always useful for diagnosis, and that’s ok: Species hypotheses should not be bound to a class of data. Reply to Brown and Gibbons (S Afr J Sci. 2022;118(9/10), Art. #12590)

This paper serves as a reply to the Commentary by Brown and Gibbons (S Afr J Sci. 2022;118(9/10), Art. #12590) on our recently published paper on systematics of the moon jellyfish genus Aurelia (Lawley et al. PeerJ 2021;9, e11954)). We emphasise that we are not advocating for the routine use of molecular data alone in taxonomic diagnoses, rather that it is a valid approach in cases where, after detailed analyses, morphological features are shown to be unreliable

Recognizing the diversity of jellyfishes (Medusozoa, Rhopaliophora)

This project aims to generate knowledge about thesystematics of jellyfish, focusing on morphological aspects and using moleculartools. Life cycle studies and biology data will also be used once they provideadditional data for identification and help comprehend the role of jellyfish inthe marine environment (blooms/outbreaks, trophic chains). The differential ofthe project lies in using an integrative approach [life cycle, biology,detailed morphology, molecular data] to diagnose and define species. It iscomposed of several smaller projects including different students andcollaborators. Concerning the systematics part: a book describing all speciesof scyphozoans and cubozoans was finished (271 species); we advanced inresolving the identification of species of the genera Aurelia,Cassiopea, Linuche and Nausithoe allof them with specimens from Brazil using both morphology and molecular data;the species Catostylus tagi from thePortuguese coast will be redescribed; the species Lychnorhiza lucerna has little genetic variability throughout itsdistributional range; data from the ultrastructure of the sperm of jellyfishescan help in distinguishing the classes Scyphozoa and Cubozoa. Concerning thebiology of species: aspects of the sexual reproduction is being investigatedfocusing on the somatic and gonadal growth; the life cycle of Catostylus tagi was studied and will bepublished soon; some species are under study to evaluate the effect oftemperature on development. Studies concerning the genome size of severaljellyfish species were conducted and data about species in cultivation willculminate with a data bank.Fil: Morandini, André C.. Universidade de Sao Paulo; BrasilFil: Cavalcante, Arthur S.. Universidade de Sao Paulo; BrasilFil: Gamero Mora, Edgar. Universidade de Sao Paulo; BrasilFil: Jordano, Mayara A.. Universidade de Sao Paulo; BrasilFil: Klovrza, Anabelle. Universidade de Sao Paulo; BrasilFil: Lawley, Jonathan W.. Griffith University; AustraliaFil: Maronna, Maximiliano Manuel. Universidade de Sao Paulo; BrasilFil: Molinari, Clarissa G.. Universidade de Sao Paulo; BrasilFil: Tiseo, Gisele R.. Universidade de Sao Paulo; BrasilFil: Schiariti, Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Stampar, Sergio. Universidade Estadual de São Paulo; BrasilXX Simpósio de Biología MarinhaSao SebastiaoBrasilUniversidad de Sao Paul