María Herranz

• PhD
• PostDoc Position at University of Copenhagen

The latest animal phylum to be discovered, Micrognathozoa, constitutes a rare group of limnic meiofauna. These microscopic ‘jaw animals’ are among the smallest metazoans yet possess highly complex jaw structures. The single species of Micrognathozoa, Limnognathia maerski Kristensen and Funch, 2000, was first described from Greenland, later reported...

Priapulida is a small phylum of 22 described species that are divided into two size classes (microscopic and macroscopic), distinguished by adult and larval morphology. Most priapulidans are rare or live in inaccessible habitats, and freshly collected material for molecular studies is difficult to obtain. With this study, we for the first time aim...

Background This study sheds light on the genetic blueprints of chaetogenesis (bristle formation), a complex biomineralization process essential not only for the diverse group of bristle worms (annelids) but also for other spiralians. We explore the complex genetic mechanisms behind chaetae formation in Osedax japonicus, the bone-devouring deep-sea...

The Ibero-Balearic area is one of the richest European regions in animal species diversity. Since 1988, the objective of the Spanish nationally funded “Fauna Ibérica” project has been to document the animal biodiversity of the area. In the context of this project, our research group initiated in 2019 the taxonomic and integrative study of the phylu...

Hemichordata has always played a central role in evolutionary studies of Chordata due to their close phylogenetic affinity and shared morphological characteristics. Hemichordates had no meiofaunal representatives until the surprising discovery of a microscopic, paedomorphic enteropneust Meioglossus psammophilus (Harrimaniidae, Hemichordata) from th...

Hemichordata has always played a central role in evolutionary studies of Chordata due to their close phylogenetic affinity and shared morphological characteristics. Neither chordates nor hemichordates had meiofaunal representatives until the surprising discovery of a microscopic, paedomorphic enteropneust Meioglossus psammophilus (Harrimaniidae, He...

A new genus and species of Loricifera, Scaberiloricus samba gen. et sp. nov., is described from the continental shelf and slope off Rio de Janeiro, Brazil. Adult morphology remains unknown for the new entity, but information is available from three different Higgins larval instars. The Higgins larva of the new species is characterised by a bulbous...

Symbiotic relationships between microbes and animals are incredibly common. However, most studies focus on the bacterial symbionts of vertebrate hosts and ignore both eukaryotic symbionts and invertebrate hosts. Some of the technical limitations complicating research into eukaryotic symbionts have largely been overcome, but there is an added wrinkl...

The fauna of Loricifera along a north-south longitudinal transect following the Atacama Trench was explored. Whereas no loriciferans were collected from the actual trench, the continental slope and surrounding abyssal plains yielded two species of Rugiloricus and two of Pliciloricus. All four species are considered as new to science, but only one o...

A new species of Echinoderes is described from the Chuuk Islands, Micronesia. Echinoderes inaequalis sp. nov. clearly belongs to the Echinoderes coulli species group due to the presence of enlarged sieve plates, reduced trunk spines (excluding the terminal series) and a hairy habitus. E. inaequalis sp. nov. is characterised by the presence of a min...

Taxonomic studies of Kinorhyncha follow a standardised structure, which is extremely useful in many aspects, such as making it easier to read and compare the different species descriptions. However, the morphological measurements methods, essential for formal description of species, may differ according to the authors. In the present contribution,...

Two new species of Echinoderes are described from Mexico. Echinoderes abeli sp. nov. is described from the archipelago Islas Marias in the Mexican Pacific Ocean west coast. The species is characterized by very short and stout lateral terminal spines, middorsal spines on segments 4 to 8 and lateroventral spines on segments 6 to 9, lateroventral tube...

Animals and microorganisms often establish close ecological relationships. However, much of our knowledge about animal microbiomes comes from two deeply studied groups: vertebrates and arthropods. To understand interactions on a broader scale of diversity, we characterized the bacterial microbiomes of close to 1,000 microscopic marine invertebrates...

The present contribution provides the first exploration of the Loricifera fauna in New Zealand. A new species, Pliciloricus apteryx sp. nov. and a new species and genus, Patuloricus tangaroa gen. et sp. nov., are described from Bay of Plenty at North Island. The latter species is represented by a Shira larva containing a different larval stage. Thi...

Mud dragons (Kinorhyncha) are microscopic invertebrates, inhabiting marine sediments across the globe from intertidal to hadal depths. They are segmented, moulting animals like arthropods, but grouping with the unsegmented priapulans and loriciferans within Ecdysozoa. There are more than 300 species of kinorhynchs described within 31 genera and 11...

Background Kinorhynch segmentation differs from the patterns found in Chordata, Arthropoda and Annelida which have coeloms and circulatory systems. Due to these differences and their obsolete status as ‘Aschelminthes’, the microscopic kinorhynchs are often not acknowledged as segmented bilaterians. Yet, morphological studies have shown a conserved...

Aberrant kinorhynchs show several modifications deviating from the typical kinorhynch body plan, including a modified introvert with very elongated and flexible scalids, a weakly developed neck, and a slender trunk with less distinct segmentation. How these aberrant external features are reflected in the inner anatomy and how their aberrant body pl...

We describe new insights into the morphology and life history of the bizarre parasite Haplozoon axiothellae (Dinoflagellata) using light microscopy (LM), scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Trophonts were isolated from the intestines of host maldanid polychaetes, Axiothella rubrocincta, collected from S...

Thirteen species of Echinoderes with nearly identical spine/tube patterns, and apparently similar tergal extensions were re-examined and compared. Based on this, redescriptions and/or emended species diagnoses are provided for Echinoderes aureus, E. dujardinii, E. gerardi, E. imperforatus, E. pacificus, E. pilosus, E. sensibilis, E. sublicarum and...

Adult dimorphism (i.e. non‐sexual dimorphism observed among sexually mature specimens) and the existence of two morphologically distinct adult stages are for the first time reported from a species of the kentrorhagid kinorhynch genus Sphenoderes. The dimorphism was found in a new species, Sphenoderes neptunus sp. nov., from the Gulf of Naples, Ital...

The publisher regrets that the presentation of Fig. 8 in the original version of this article contained an error where all serotonergic somata , represented as blue circles in Fig. 8c, with associated labels ‘vms’ and ‘vncs5’ were omitted during the publication process

Comprehensive morphological investigations covering the diversity of metazoan lineages are needed to obtain a complete picture of organ system evolution. Despite the increased amount of studies on lesser-known phyla during the last decades, the gap in knowledge for these lineages is still remarkable. This is the case for kinorhynchs, or mud dragons...

An interactive, continuously updated identification key to species of the large kinorhynch family Echinoderidae has been made available online. The key is based on the DELTA format (DEscription Language for TAxonomy), and provides, with a multiple entry approach, an intuitive and user friendly tool to identify more than 145 echinoderid species. The...

Since its discovery in the mid-1950'ies, Cateria has been an enigmatic kinorhynch genus due to its aberrant worm-like shape and extremely thin cuticle. However, the rare occurrence of the species, only found in sandy intertidal habitats, and the poor preservation of the type material have hampered detailed studies of the genus over time. Now, sixty...

The application of metabarcoding to study animal‐associated microeukaryotes has been restricted because the universal barcode used to study microeukaryotic ecology and distribution in the environment, the Small Subunit of the Ribosomal RNA gene (18S rRNA), is also present in the host. As a result, when host‐associated microbial eukaryotes are analy...

To date, sea slugs have been considered the only animals known to sequester functional algal plastids into their own cells, via a process called “kleptoplasty.” We report here, however, that endosymbionts in the marine flatworms Baicalellia solaris and Pogaina paranygulgus are isolated plastids stolen from diatoms. Ultrastructural data show that kl...

Kinorhyncha is a phylum of microscopic, benthic marine invertebrates found throughout the world, from the Arctic to Antarctica and from the intertidal zone to the deep sea. Within the most species-rich genus, Echinoderes, we find a putatively monophyletic species group, the so-called Echinoderes coulli-group. The remarkable morphological similariti...

Background The Scalidophora (Kinorhyncha, Loricifera and Priapulida) have an important phylogenetic position as early branching ecdysozoans, yet the architecture of their nervous organ systems is notably underinvestigated. Without such information, and in the absence of a stable phylogenetic context, we are inhibited from producing adequate hypothe...

Dinoflagellates are some of the most common eukaryotic cells in the ocean, but have very unusual nuclei. Many exhibit a form of closed mitosis (dinomitosis) wherein the nuclear envelope (NE) invaginates to form one or more trans-nuclear tunnels. Rather than contact spindles directly, the chromatids then bind to membrane-based kinetochores on the NE...

Background: Unlike the study of bacterial microbiomes, the study of the microeukaryotes associated with animals has largely been restricted to visual identification or molecular targeting of particular groups. The application of high-throughput sequencing (HTS) approaches, such as those used to look at bacteria, has been restricted because the barc...

Barriers to gene flow in marine environments vary between species and are highly dependent on dispersal ability and habitat discontinuity. Intertidal sand and mud flats are discontinuous areas, separated by other habitat types along a coastline or by subtidal zones. The São Sebastião Channel in eastern Brazil, which is situated between Rio de Janei...

Surveys of kinorhynch diversity in the northeastern Pacific Ocean are rare, and only eight species have been described from the region so far. We explored the diversity of kinorhynchs from a pristine coastal habitat of British Columbia (Calvert Island) and discovered a new subtidal species, Echinoderes hakaiensis sp. nov.We also redescribed one of...

We examine the origin of harpoon-like secretory organelles (nematocysts) in dinoflagellate protists. These ballistic organelles have been hypothesized to be homologous to similarly complex structures in animals (cnidarians); but we show, using structural, functional, and phylogenomic data, that nematocysts evolved independently in both lineages. We...

Sampling for meiofauna was carried out in 2010 in Bocas del Toro, Northwest Caribbean Panama, as the first part of a study along Caribbean and Pacific coasts of Panama. Nine kinorhynch species were known previously from the area, some of them being confirmed in the present contribution plus several new citations. In addition, four species new to sc...

Meiofaunal sampling was carried out in 2011 in the Pacific coast of Panama, West of Panama City and Las Perlas Archipielago. No kinorhynch species have previously been reported from the area. Seven species were found, four of them new to science: Echinoderes belenae sp. nov., Echinoderes muricatus sp. nov., Echinoderes strii sp. nov., and Cristaphy...

The first exploration of the kinorhynch meiofauna in Portuguese marine waters has revealed the existence of two undescribed species of the cyclorhagid genus Echinoderes. In the present contribution we describe Echinoderes lusitanicus sp. nov. and Echinoderes reicherti sp. nov., both collected from subtidal regions of the coast of Algarve in the sou...

Sampling of meiofauna along the US continental shelf of the Gulf of Mexico has been carried out in an eight year period, from 2007 to 2014. Studies of the kinorhynch fauna from these collections have resulted in the description of two new species, Echinoderes augustae and E. skipperae. The present contribution includes new recordings of E. augustae...

The phylogeny of Kinorhyncha was analyzed using morphology and the molecular loci 18S rRNA and 28S rRNA. The different datasets were analyzed separately and in combination , using maximum likelihood and Bayesian Inference. Bayesian inference of molecular sequence data in combination with morphology supported the division of Kinorhyncha into two maj...

Kinorhyncha is a clade of marine invertebrate meiofauna. Their body plan includes a retractable introvert bearing rings of cuticular spines, and a limbless trunk with distinct segmentation of nervous, muscular and epidermal organ systems. As derived members within the basal branch of Ecdysozoa, kinorhynchs may provide an important example of conver...

Two new species of homalorhagid kinorhynchs of the genus Pycnophyes, Pycnophyes almansae sp. nov. and Pycnophyes lageria sp. nov., are described from the Atlantic and Spanish waters of the Mediterranean Sea, using scanning electron microscopy and differential interference contrast microscopy. Pycnophyes almansae sp. nov. is recognized by the presen...

The present contribution includes the description of two new species of the phylum Kinorhyncha collected off the East coast of Florida, USA and assigned to two recently and still poorly known genera:Fissuroderes Neuhaus and Blasche, 2006 and Meristoderes Herranz et al., 2012. They both belong to thefamily Echinoderidae Bütschli, 1876. Species of Fi...

Four new species of Kinorhynchs are described from the West Atlantic coast off Fort Pierce, Florida, USA. They are the following: Antygomonas gwenae n. sp., Echinoderes riceae n. sp., Echinoderes adrianovi n. sp. and Pycnophyes norenburgi n. sp. All species were collected at the same locality called ‘‘20 miles station.’’ Samples were processed for...

Cycloneuralian taxa exhibit similar organ system architectures, providing informative characters of metazoan evolution, yet very few modern comparative descriptions of cellular and molecular homologies within and among those taxa are available. We immunolabeled and characterized elements of the serotonergic nervous system in the kinorhynchs Echinod...

A new kinorhynch genus, Meristoderes gen. nov., and two new species from Spain and the Solomon Islands, respectively, are described. The new genus is distinguished from all other genera by the first segment consisting of a closed cuticular ring, and the second segment having partial tergosternal junctions, and a superficial midventral fold. This is...

Data are presented from the first intensive sampling of Kinorhyncha around the Iberian Peninsula over a 21-year period from 1990 to 2011, from 81 sites mostly in less than 100 m water depth. Light-microscopic examination of approximately 2000 specimens yielded 11 genera and 29 species, only 11 of which were previously recorded from peninsular water...

The type species of Dracoderes, D. abei, is redescribed based on specimens from several localities in Japan and Korea, and a new species of the genus, Dracoderes gallaicus sp. nov., is described from the coast of Spain in Western Europe. The new species is distinguished by the presence of lateral accessory spines on segment 5. In addition, prelimin...

Two new species of the kinorhynch genus Pycnophyes are described from the Atlantic Ocean, Northwest Spain, and the Mediterranean Sea, East of Spain, using differential interference contrast microscopy and scanning electron microscopy (SEM): Pycnophyes dolichurus sp. nov. and P. aulacodes sp. nov. Taxonomic characters from cuticular structures in ho...

The kinorhynch genus Paracentrophyes currently consists of two species only: P. quadridentatus (Zelinka, 1928) from the Mediterranean Sea and P. praedictus Higgins, 1983 from Belize in the Caribbean. Both species have until now been recorded from their type localities only. In the present contribution a new species of Paracentrophyes, P. anurus sp....