Taxonomy and distribution of Italian and Antarctic Pycnogonida, with identification keys to genera and species

openQuesta tesi fornisce una descrizione dei progetti realizzati nel triennio 2018-2021 nell'ambito dello studio dei Picnogonidi. Viene riportata una panoramica generale della classe Pycnogonida (Arthropoda, Chelicerata), evidenziando le principali caratteristiche di questi organismi. Successivamente viene proposta la checklist aggiornata dei Picnogonidi italiani (Colasanto e Galli, 2021) con la distribuzione dettagliata delle specie, generata undici anni dopo quella di Bartolino e Chimenz (2010). La chiave dicotomica proposta per l'identificazione delle specie fa riferimento a questi documenti. La chiave è stata ottenuta attraverso indagini bibliografiche sulle caratteristiche morfologiche della specie, integrando con informazioni tratte da chiavi già presenti in letteratura (in particolare, Munilla e Soler-Membrives, 2014) e analisi di campioni in laboratorio. Parallelamente allo studio dei Picnogonidi italiani, sono stati esaminati gli esemplari conservati al Museo Nazionale dell'Antartide ed è stato effettuato uno studio di DNA barcoding su alcuni di essi. Sono state abbozzate chiavi di identificazione di generi e specie, sulla base delle caratteristiche morfologiche. Conseguentemente, viene riportata anche la checklist aggiornata dei Picnogonidi antartici e sub-antartici. Si riportano infine alcune considerazioni sulla possibilità di coinvolgere i subacquei nel monitoraggio dei Picnogonidi attraverso progetti di citizen science.This thesis provides a description of the projects carried out in the three-year period 2018-2021 as part of the study of Pycnogonida. A general overview of the class Pycnogonida (Arthropoda, Chelicerata) is reported, highlighting the main characteristics of these organisms. Subsequently, the updated checklist of the Italian pycnogonids (Colasanto and Galli, 2021) is proposed with the detailed distribution of the species, generated eleven years after that of Bartolino and Chimenz (2010). The dichotomous key proposed for the species identification refers to these documents. The key was obtained through bibliographic investigations on the morphological characteristics of the species, integrating with information taken from keys already present in the literature (in particular, Munilla and Soler-Membrives, 2014) and laboratory analysis of samples. Parallel to the study of the Italian pycnogonids, specimens preserved at the National Museum of Antarctica were examined and the barcoding DNA of some of them was sequenced. Identification keys to genera and species were sketched, based on morphological characters. Therefore, the updated checklist of Antarctic and sub-Antarctic Pycnogonida is also reported. Finally, some considerations on the possibility to involve Scuba-divers on pycnogonids monitoring through citizen science projects are reported.openXXXIV CICLO - SCIENZE E TECNOLOGIE PER L'AMBIENTE E IL TERRITORIO (STAT) - Scienze del mareColasanto, Elis

Evolution of pycnogonid life history traits

The Pycnogonida is a class of arthropods with interesting life histories. Pycnogonids prey on hydroids and some invade hydranths while larvae. Males brood the eggs and larvae hatch as protonymphons. Questions relating to the evolution of life history characteristics were addressed. Evolutionary relationships were poorly understood. It was necessary to determine the relationships within the Pycnogonida and compared to other arthropods. Twenty-four morphological characters were coded for twenty-three pycnogonid genera and one fossil ancestor, Palaeoisopus problematicus. A branch and bound analysis resulted in fifteen most parsimonious trees. The Nymphonidae were found to be basal. The Ammotheidae were paraphyletic and led to two clades. The first contained the Callipallenidae, and Phoxichilidiidae. The second contained the remaining pycnogonids. A phylogeny was also compiled using sequences of the D3 expansion segments of 28S rDNA. This resolved relationships of sampled families as follows (Ammotheidae + ((Nymphonidae + Colossendeidae) + (Endeididae + (Pycnogonidae + Phoxichilidiidae)))). The Ammotheidae was found to be paraphyletic and basal. The results from the D3 region yielded perplexing relationships when compared with morphology. Phoxichilidium tubulariae Lebour 1947 is a valid species. It appeared to be specialists on the hydroid Tubularia larynx. Annual population dynamics of P. tubulariae were seasonal. Density of adult animals was highest in mid to late summer with reproduction being greatest in July and August. The abundance of pycnogonids peaked as the hydroid population declined. Some populations were shown to have two generations. Adult migration may play a larger role in the distribution of this species than larval dispersal. Phoxichilidium tubulariae had an atypical protonymphon type developmental mode that reduced the typical number of molts, and developed rapidly in the gastrovascular cavities of the host. It decreased developmental time from 35--40 days to 15--20 days. This was adapted to exploit the seasonal abundance of Tubularia larynx. The male looped the egg mass over his oviger. The larvae hatched, infected the hydroid, and developed inside the gastrovascular cavity of T. larynx. The larvae developed for several molts and then hatched, destroying the hydranth. The ancestral pycnogonid stock were external parasites. The internalization of the larval stages appeared to have happened at least twice

Notes on Pantopoda

Rhynchothorax mediterraneus Costa 1861 e Anoplodactylus robustus (Dohrn) 1881 dragados em fundo de Lithothamnion na região da Ilha da Trindade (20º30'S-29º22'W), são descritos. Três espécimes imaturos, em seqüência de desenvolvimento, pertencem ao gênero Rhynchothorax Costa 1861, pela primeira vez assinalado em águas brasileiras. Espécime mais jovem - apresenta tubérculo ocular semelhante a cone truncado, giba dorsal na proboscis, palpo sem o número definitivo de artículos, ovígero ausente, quarto par de pernas ambulatórias sem tarso. Comprimento: 660 micra. Espécime intermediário - ovígero presente, representado por um botão; quarto par de pernas ambulatórias com todos os artículos. Comprimento:1.215 micra. Espécime mais desenvolvido - semelhante ao adulto descrito por Dohrn (1881, p. 211-215), apresenta tubérculo ocular em forma de espora, giba dorsal na proboscis ausente, palpo com o número definitivo de artículos; ovígero 10-articulado; gônadas e glândulas de cimento ausentes. Comprimento : 1.290 micra. A ausência de olhos nos exemplares sugere a possibilidade deste material representar variedade cega de Rhynchothorax mediterraneus Costa 1861. Anoplodactylus robustus (Dohrn) 1881, descrito anteriormente como Halosoma robustus (Marcus 1940, p. 68), diverge deste último na ausência de segmentação, ovígero 6-articulado, desembocadura das glândulas argamassadoras em protuberância dorsal localizada no fémur de todas as patas ambulatórias. Caracteres anatômicos fundamentam a inclusão da espécie em Anoplodactylus (Stock 1954, p. 70)

Pycnogonids (Arthropoda: Pycnogonida) of Portofino, Ligurian Sea (North-Western Mediterranean Sea)

Pycnogonida collected monthly from September 2017 to August 2018 in the Portofino Marine Protected Area at 0\u20135 m depth were studied. A total of 499 specimens were collected, 457 of which were identified to species level. These were classified as belonging to 10 species: Achelia echinata*, Ascorhynchus castelli, Neotrygaeus communis*, Tanystylum conirostre*, Anoplodactylus angulatus, A. petiolatus, A. pygmaeus*, A. virescens, Callipallene phantoma and C. tiberi*. For five dominant species (those marked with an asterisk) the annual phenology was outlined. Four hundred and seventeen additional specimens, collected from the same area and depth range mainly during the 1970s and 1980s were identified to species level for completeness of information, leading to the addition of Pycnogonum pusillum and Endeis spinosa

Spatial Patterns of Marine Larvae as Indicators of Incipient Invasions in Great Bay

Understanding the dynamics of coastal marine communities represents a substantial challenge, and one that is actively pursued globally. Within the United States, several sites have been designated as National Estuarine Research Reserves (NERR) with the idea that concentrated research at these sites will lead to greater understanding of the ecosystem. The Great Bay Estuary of New Hampshire is one of these sites. A wide spectrum of research is conducted within the Great Bay, and substantial financial support is committed to that research on an annual basis. To facilitate the success of these research efforts, it is particularly important to develop a working understanding of the dynamics of marine communities within the Great Bay. Invertebrate communities within the Bay and at other coastal sites are largely composed of open populations whose growth and maintenance depend on settlement of new recruits that may arrive from distant source populations. Larval monitoring programs designed to survey these incoming recruits should therefore be an important component of the research program within the Great Bay and other NERR sites. By monitoring recruitment within the Great Bay, we may begin to determine larval spatial patterns within potential habitats. This will then allow for comparison of observed larval spatial patterns and observed adult population distributions. If the two are similar, this would indicate that future adult populations can be predicted by knowledge of larval settlement. If the two are dissimilar, this indicates a need to investigate causes of post-settlement mortality that lead to discrepancies in larval and adult abundances. For example, if there is a large discrepancy between larval and adult abundances, then the Great Bay may be acting as a sink for some species whose larvae are transported into the bay, but do not survive to establish adult populations. By monitoring invertebrate recruitment into the Great Bay, we begin to establish a baseline for biotic conditions within the Bay against which future conditions can be compared. This is a crucial step in determining the effects of anthropogenically induced environmental changes, such as the introduction of nonindigenous species. Furthermore, we predict that because a sufficient influx of larvae is needed to establish a viable adult population, larvae of exotic species not currently present in Great Bay will be first detectable in the plankton, perhaps for several years before they arrive in sufficient numbers for adults to establish. This may provide an advanced warning of incipient invasions and allow managers to develop plans for eradication or mitigation in advance of the exotic species’ establishment. Here we report on a study designed to collect the baseline data necessary to establish patterns and make comparisons to future conditions. We have collected larvae on artificial settlement substrates at six sites within the Great Bay Estuary and at an adjacent coastal site during ice-free months since July 2002. This report gives a brief description of the results of this monitoring program to determine the species composition, spatial patterns, and timing of invertebrate settlement within the Great Bay. This report specifically includes data from April 2005 to June 2006, the portion of the project funded by NHEP. Data from 2002-04 are also available, but are not included in this report