Female monogonont rotifers are among the smallest animals, with many species less than 100 mm in length. Male rotifers are enigmatic; they are only known for relatively few species, are infrequently seen, and are usually smaller than their female counterparts, often lacking a complete gut. Consequently, knowledge of their morphology is scarce, particularly so with respect to the fine details of their copulatory apparatus. In this study, we apply confocal laser scanning microscopy and transmission electron microscopy to study the copulatory (penis) organ of Asplanchnopus aff. multiceps, for which no data is currently available. Our studies revealed the copulatory organ to be a complex structure with a circumferential ciliated band, a microvillar tip with an actin rich terminal web, and an intricate musculature that functions in protraction and retraction. Two prostate glands and two accessory glands supply the male apparatus. The overall organization of the organ fits into a “type” that characterizes the family Asplanchnidae, with the main exception being the possession of a microvillar tip. Complexity of the organ, which functions purely in attachment to the female and not insertion, is perplexing considering its size (~ 10 mm) and the apparent simplicity of its function. We hypothesize that other male organs are probably equally complex, but their size has limited our knowledge of their anatomy, which might otherwise provide valuable details for both taxonomic studies and a better understanding about the evolution of reproductive structures and behaviors throughout the phylum.

Gastrotricha is a group of microscopic animals that are often overlooked in ecological surveys, despite their worldwide distribution across all oceans on Earth. The apparent incongruence between widespread distribution of microscopic animals and their life history is known as the ‘‘meiofauna paradox’’. This concept has been investigated in many meiofaunal groups and recent studies provide new insights revealing that the restricted distribution of these organisms is more common than was previously thought based on molecular diversity and muscular organization. The use of integrative morphological methods has been used in the past decades to increase the accuracy of species delimitation. In the present study we discovered a new species of the genus Kryptodasys (Macrodasyida: Macrodasyidae) from Capron Shoal, Florida, USA. For species delimitation, we used traditional light microscopy and Confocal Laser Scanning Microscopy (CLSM). The specimens of the new species show a unique reproductive apparatus and for the first time in the group, a muscular complex dedicated to the seminal vesicle is described. Also, a complex caudal organ composed of two compartments were observed. The complete muscular analysis added important novelties to the knowledge of muscular architecture of Macrodasyida group and to the phylum.

The hyperbenthic zone, the transition between pelagial and benthos, is known as an environment of unique interactions with endemic species. Taxa inhabiting the marine benthic and hyperbenthic zone are often deemed as having the most plesiomorphic characters, making the study of hyperbenthic species essential to understanding the evolutionary history of several taxa, among them copepods. One copepod family whose representatives are found especially within deep-sea hyperbenthic communities is the Aegisthidae Giesbrecht, 1893, which, together with the family Rometidae Seifried & Schminke, 2003, is considered the sister group to all remaining Harpacticoida. Whilst efforts have been made to unravel phylogenetic relationships within Aegisthidae, the monophyly of the hyperbenthic genus Pontostratiotes Brady, 1883 has yet to be tested across specimens from both the Pacific and the Atlantic Ocean. Here, we apply an integrative approach, combining the inference of a phylogenetic tree, including the gene fragment of mitochondrial cytochrome oxidase c subunit I, as well as nuclear sequences of 18S and 28S, with high-resolution imaging techniques—confocal laser scanning microscopy and synchroton radiation-based microcomputed tomography—for detailed morphology documentation. The Pontostratiotes specimens analyzed were collected during expeditions across the North Atlantic Ocean (IceAGE, IceAGE 3, IceDivA, IceDivA 2). Our analyses, including the molecular data available, which originate almost exclusively from Pacific samples, recovered the subfamily Pontostratiotinae, including all members of Pontostratiotes, as monophyletic. Four of the nine resulting species clusters of Pontostratiotes specimens examined in this study were assigned to valid species, while five previously undescribed lineages were provided with molecular barcodes and morphological descriptions. The examination of spatial records of the genus lead to the assumption of a near-worldwide distribution. As closely related benthic harpacticoid copepods are seldomly found in multiple samples across greater distances, abundant specimens of Pontostratiotes could be a good proxy to understand the connectivity of North Atlantic communities.

Chamaeza campanisona is a species complex with cryptic diversity and currently has 12 recognized subspecies, predominantly distributed along altitudinal and longitudinal gradients in the Andes. Within the Atlantic Forest, two subspecies are currently recognized. Given the limited taxonomic studies of this genus, we investigated vocal variation among Atlantic Forest populations of this species complex. We analyzed 183 recordings obtained from the Macaulay Library, WikiAves, and Xeno-Canto databases and examined 56 specimens housed at the Museu de Zoologia da Universidade de São Paulo. Vocalizations were analyzed using Raven Pro 1.6.5. Comparisons between populations were made with Multivariate analysis of variance (MANOVA) within the R environment. The following measurements were analyzed: bill height, width and length, tarsus, tail, and wing length. Statistical analysis was not conducted, due to the limited sample size (only one specimen from the northeastern Brazilian population). Plumage coloration was color-coded and compared across specimens. All examined C. campanisona specimens exhibited a distinct black patch on the front, whereas the single specimen from northeastern Brazil lacked this trait. The loudsongs typically consist of rapid series of short-spaced notes, with population-specific variation particularly in pace and in the presence of a terminal series of slowed, descending grunting notes. Our analyses revealed two distinct loudsong patterns: a southern variant occurring from southeastern Paraguay and northeastern Argentina north to Bahia state in Brazil, and a pattern restricted to Ceará state, northeastern Brazil. MANOVA revealed significant differences between populations (p < 0.001). Specifically, song duration varied significantly, whereas maximum entropy differed across populations (p < 0.001). The southern vocal type corresponds to C. campanisona, whereas the northeastern population represents a morphologically and vocally diagnosable unrecognized taxon, which requires formal description once more detailed information on other northeastern specimens is made available.

Sponges are one of the most representative and abundant benthic groups, with records from different environments and depths. Regarding their diversity, around 450 marine species are described in the Brazilian Exclusive Economic Zone (EZZ), with only 17 of them belonging to the class Hexactinellida. These sponges are found in cold and deep waters and remain poorly studied due to the high costs and logistical challenges of sampling. This study aims to describe hexactinellid species of the family Hyalonematidae, sampled in the Southwestern Atlantic (Campos Basin, off Rio de Janeiro state), and deposited at the Museu Nacional (MNRJ-UFRJ), in Rio de Janeiro, Brazil. The three specimens analyzed here belong to Hyalonema. This genus encompasses 100 species described worldwide, which are classified in 12 subgenera. In Brazil, four species have been recorded to date: H. (Coscinonema) schmidti, H. (Cyliconema) conqueror, H. (Cyliconemaoida) alucia, and H. (Prionema) dufresnei. Among the specimens examined, two potentially new species are being described, one H. (Corynonema) sp. and one H. (Cyliconema) sp. Notably, the former represents the first record of this subgenus in the Atlantic Ocean. Hyalonema (Cyliconema) sp. is characterized by acanthophorae in its basalia, pinnular pentactines in the dermalia and atrialia, diactins, hexactins, and pentactins in the choanosome, as well as amphidisc microscleres (macro-, meso-, and microamphidiscs). In turn, H. (Corynonema) sp., presents basalia with acanthophorae, pinnular pentactins and hexactins in its dermalia and atrialia, diactins, pentactins and hexactins in the choanosome, together with amphidisc microscleres (macro-, meso- and microamphidiscs) and microhexactins. The uniqueness of the samples, the potential discovery of new species, and the first Atlantic record of the subgenus highlight the need for further taxonomic studies on the group, which appears to be markedly understudied in the SW Atlantic.

The shallow waters of the Indo-Pacific Ocean are known for harboring an immense biodiversity of organisms, specifically sponges (Porifera). An expedition conducted by the National Institute of Health (NIH) collected six species of sponges with potential medicinal properties from Thailand and Papua New Guinea. This project aims to identify, classify and describe those specimens, so that their names can be linked to the biomedical compounds described by the NIH. All samples were deposited at the Smithsonian National Museum of Natural History, and identifications followed standardized taxonomic protocols. To date, the classification of four specimens has been narrowed down to a lower taxonomic level. Three specimens were identified in the order Axinellida: Specimen 1 is a Raspaillidae, with a smooth, paper-like surface and massive shape. It presents oxeas, styles and subtylostyles. Specimen 2 is an Axinellidae, with a smooth, massive cylindrical shape. It has oxeas, raphidiform oxeas, and very rare styles. Specimen 3 is an Axinellidae that has a dichotomous branching body-shape, with worm-like strongyles and styles. The fourth specimen was identified in the genus Wigginsia (family Acarnidae, order Poecilosclerida) based on its choansomal tylotes and acanthostrongyles. All sponges will be identified to the lowest taxonomic unit possible and new species will be named and described. The next step to improve species identification and describe morphological details is to obtain images of spicules under a scanning electron microscope.

Advancing current knowledge about deep-sea shrimps is challenging, considering the difficulty in sampling organisms and the damaged state in which they arrive at the surface after collection. Thus, several aspects of their biology and ecology remain unknown or poorly understood, despite the importance of many species to worldwide fisheries. Integrative taxonomic approaches, merging morphological and DNA barcoding analyses, have been useful to obtain more information about these crustaceans. The family Benthesicymidae, which includes benthopelagic species inhabiting depths of 500 to 2000 m, remains among the least understood, since information available for both larvae and adults is scarce. The taxonomy of the family has been phylogenetically reviewed in recent years, as in the case of Benthesicymus, now considered a paraphyletic genus with two species—Benthesicymus crenatus and Benthesicymus laciniatus. Previously described species of the genus were reassigned to new and distinct genera within the family Benthesicymidae. The present study provides an extension of a previous work in which we reported the first description of the decapodid stage of B. laciniatus using integrative taxonomy by adding the first description of the zoeal stages of the species. Specimens were collected in the neuston layer (surface of the water column) during a sea survey in the Madeira-Tore geological complex in the north-eastern Atlantic. Several morphological characters distinguished the individuals from closely related taxa described in the literature, especially regarding the abdominal spines and the telson shape. The morphology of the sampled larval stages is discussed and compared with the available knowledge for Benthesicymidae shrimps, adding new knowledge for future taxonomic studies and clarifying older larval descriptions. Insights into the larval ecology of the species are provided, with a focus on its adaptations to a neustonic lifestyle.

During a study of the monogeneans of three freshwater fishes (Ompok bimaculatus, Chanda nama, and Notopterus notopterus) from the River Ganga, a total of five parasites (Chandacleidus recurvatus, Notopterodiscoides notopterus, Spicocleidus namae, Thaparocleidus malabaricus, and Thaparocleidus octotylus) of the family Dactylogyridae were characterized molecularly (18S rRNA gene). Our study provides the first 18S molecular data for Chandacleidus recurvatus, Notopterodiscoides notopterus, Spicocleidus namae, Thaparocleidus malabaricus, and Thaparocleidus octotylus. The present study's phylogenetic analysis for the abovementioned species, developed here, revealed the importance of molecular approaches in the study of monogenean diversity. Although in Indian region, despite the high diversity of monogenean parasites from the freshwater fish hosts, little is known about their genetic diversity. Therefore, an integrative approach further will help to increase the exactitude of genetic diversity and phylogenetic relationships of this group of parasites. 

The family Serrasalmidae, which is exclusively formed of Neotropical freshwater Characiformes, comprises 18 South American genera with 105 described species. Most of this species is represented in the fossil record, with one species now extinct. Reviewing the teeth morphology of this family is of great relevance, given the recurrent use of dental morphology in taxonomic classification and in identifying fossil teeth within the family’s extinct forms. The goal of this study was to review the dental morphology and taxonomy of the main current representatives of this family. The specimens analyzed are in the ichthyological collection of the State University of Rio de Janeiro (UERJ). The specimens studied (Metynnis fasciatus Ahl 1931, Metynnis guaporensis Eigenmann 1915, Myloplus arnoldi Ahl 1936, and Pygocentrus nattereri Kner 1858) were identified using bibliographic references, dissected, and their skeletons were prepared using dermestid beetles. The dentary and premaxillary bones were then extracted for detailed analysis. The teeth of Myloplus arnoldi and Metynnis are molariform, with slightly elevated and convex crowns, asymmetrical cusps, external ones larger and darker (brown) than internal ones (white), broad roots, laterally long and deeply anchored in the dentary, and a wide, smooth surface. These analyses allowed us to identify differences in the heterodonty patterns between the two genera. Pygocentrus nattereri's teeth are caniniform, with long, flat, high crowns, sharp serrated edges, broad conical roots tightly set into the dentary, and a smooth, triangular, whitish surface. In conclusion, this study deepens the discussion on the relationship between dental morphology and taxonomic classification of this family, along with its fossil identification. The data from this study will contribute to a better understanding of morphological–taxonomic relationships, offering a more categorized view of Serrasalmidae dental morphological traits.

Over the last two decades, a team of Spanish researchers has developed the ECOAFRIK project, which aims to study the biodiversity and benthic habitats from African seas. The group has taken advantage of the opportunity provided by several international bottom-trawling surveys (13 surveys, 1600 stations) carried out in northwest Africa to acquire large collections and biological and environmental data. This has improved our knowledge about the biodiversity and distribution of vulnerable marine ecosystems, mainly in deep-sea waters of the CCLME region. As results of our extensive taxonomic and ecological research more than 12 taxa ―already identified (as Decapoda, Bivalvia, Gastropoda, Cephalopoda, Hydrozoa, Ophiuroidea, Holothuroidea, Scleractinia, Pycnogonida, Pennatuloidea), or currently under study (other Octocorallia groups, Actiniaria and Porifera)― we have described 20 new species, and produced six PhD thesis (plus five in preparation), 20 Bachelor and Master Degree Dissertations, 65 scientific papers and more than 80 communications in international forums. A monographic volume published by Springer offered a characterization of the benthic biodiversity and main deep-sea ecosystems off Mauritania. This knowledge represented the basis of the proposal to establish the first deep-water MPA network in Africa. The current team, associated in the EcoAfrik scientific Platform includes professors, senior and postdoctoral researchers, as well as PhD and master's students. The team has a high degree of specialization in taxonomic research, teaching, knowledge transfer, training, advice and dissemination in the field of biodiversity and marine habitats.