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Morphology and ecology of Stylasteridae (Cnidaria, Hydrozoa)
No full textLa famiglia Stylasteridae è una della due famiglie di idroidi a presentare uno scheletro calcareo
chiamato coenosteum.
Gli Stylasteridae sono idroidi polimorfici e presentano due tipi di polipi che escono lungo il
coenosteum attraverso dei pori. La distribuzione dai pori lungo la colonia e la loro forma sono
caratteristiche strettamente legate al genere. I polipi di una colonia sono connessi attraverso una
fitta rete di canali cenosarcali che permea l’intero scheletro.
Durante il dottorato, la morfologia dello scheletro degli Stylasteridae è stata studiata per la prima
volta attraverso l’utilizzo della microtomografia computerizzata a raggi X (Xray μCT). E’ stato
dimostrato come questa tecnica non distruttiva risulti molto utile nello studio della morfologia
scheletrica ed inoltre è stato osservato come l’approccio integrato tra questa tecnica e il tradizionale
tecnica SEM permetta uno studio più approfondito e dettagliato della tassonomia di questa famiglia.
Infatti, i risultati ottenuti attraverso la combinazione di queste due tecniche permettono
l’identificazione di caratteri morfologici che altrimenti potrebbero venire male interpretati o
addirittura potrebbero passare inosservati.
Lo studio dei primi stadi di crescita di alcune specie di Stylasteridae ha mostrato come in
quest’ultime il primo step sia la formazione di un ciclosistema primario, anche nel caso in cui da
adulte esse presentino una differente distribuzione di pori. Questi dati hanno portato a due ipotesi: 1.
ciclosistema come distribuzione tipica dei pori dall’antenato di questa famiglia; 2. ciclosistema
come miglior tipo di distribuzione per la protezione del primo gastrozoide da parte dei dattilozoidi.
Il presente studio riporta, inoltre, la dettagliata descrizione della modalità di crescita di due specie di
Distichopora, dalla formazione del ciclosistema primario fino alla formazione della colonia adulta
che presenta una distribuzione di pori in file.
Sono stati condotti degli studi anche dal punto di vista della riproduzione. Uno studio preliminare
ha consentito di capire in dettaglio la morfologia e lo sviluppo dei gonofori di quattro specie di
Stylasteridae indonesiani. Inoltre, attraverso uno studio ultrastrutturale, sono stati descritti alcuni
step della spermatogenesi, fino al differenziamento degli spermatozoi, in una specie di Distichopora.
Lo studio effettuato in merito alla fauna associata ha messo in luce la simbiosi di alcune specie di
Stylasteridae con i cirripedi lepadomorfi. Inoltre, è stato dimostrato come gli Stylasteridae,
nonostante il loro scheletro calcareo, non siano facilmente attaccabili da parte delle spugne
perforatrici.Stylasteridae is one of the two hydroid families having hard, calcareous skeleton.
The stylasterids are polymorphic hydroids having two different kinds of polyps lodged in pores.
The distribution of the pores over the coenosteum and their shapes are features strictly related to the
genera. All the polyps of a colony are connected by a network of coenosarcal canals that densely
perforate the coenosteum.
The morphology of the stylasterid skeleton was finely investigated for the first time using the X-ray
computed microtomography technique (μCT). The utility of this technique for the non-destructive
study of coral morphology was showed, demonstrating the benefit of the integrated analysis of
pictures produced by X-ray μCT and the traditional SEM techniques in coral taxonomy. Indeed the
combined results allow the identification of morphological characters that otherwise could be
misidentified or even could pass unnoticed.
The observation of post-larval specimens belonging to several species that when adult show pores
arranged in rows, in cyclostystems or without coordination revealed that they invariably produce a
primary cyclosystem. These data lead to the hypothesis that the cyclosystem represents the pore
organisation of the family ancestor or that this organisation provides greater protection to the young
gastrozooid by the dactylozooids.
The present study reports also the first detailed description of the growth stages of two Distichopora
species showing the formation of a primary cyclosystem and the description of the growth process
from primary cyclosystem to adult pore organisation.
From the reproductive point of view a preliminary survey was carried out about the morphology of
the reproductive structures and the development of the gonophores of four Indonesian species. In
addition for the first time a detailed description, at ultrastructural level, of some steps of the
spermatogenesis up to spermatozoa differentiation in a Distichopora species was provided.
The study of the associated fauna showed the first evidence of stylasterids associated to goose
barnacles. Moreover the survey concerning the association between sponges and stylasterid corals
reveled no specific association and generally the recorded sponges bore only the dead portion of the
colonies not enveloped by living epithelium and lacking the coenosteal stolon network
Investigation of nematocysts in stylasterids (Cnidaria: Hydrozoa: Stylasteridae)
No full textThe type, size, shape and distribution of nematocysts represent important taxonomic characters that help to identify many hydrozoan species. The Stylasteridae is one of the most species-rich hydroid families. Nevertheless, information about the soft tissue and especially data about the nematocysts are still very scant. Scattered data about nematocysts are available in several taxonomic papers, but unfortunately without the type identification or shape description, this information is not very useful. Therefore, several questions still need answers. What types of nematocysts are present in the stylasterid family? Do nematocysts have a particular distribution in the soft tissue? Could they be considered a useful taxonomic character for the family? Is it possible to hypothesize their functions? In order to answer these questions, we analysed 15 stylasterid species belonging to seven genera. Euryteles, desmonemes, isorhizas and probably also mastigophores were identified. All examined species have euryteles and desmonemes, while isorhizas are recorded in two genera and mastigophores in only one genus. Moreover, the shape of the nematocysts in some species is very distinct. The distribution of nematocysts shows that each species contains, in the coenosarc, all nematocysts of its cnidome, while in the polyps there are only euryteles and desmonemes. Our study showed that in integrating the information about nematocyst type, size, shape and distribution, each species investigated herein has a specific cnidome. Therefore, nematocysts have a taxonomic value for stylasterids and, whenever possible, nematocysts should be included in the species descriptions. Moreover, the possible functions of stylasterid nematocysts are given in relation to their type and distribution.</p
Fig. 27. Hemiasterella complicata Topsent, 1919. A in Porifera from Ponta do Ouro (Mozambique)
No full textFig. 27. Hemiasterella complicata Topsent, 1919. A. The specimen PO20 in situ. B. The specimen IMG 516. C. Ectosome constituted by densely packed euasters (SEM). D. Choanosomal skeleton (SEM). E. Strongyloxea and oxea. F. Strongylaster. G. Smooth oxyasters.Published as part of Calcinai, Barbara, Belfiore, Giuseppe, Pica, Daniela, Torsani, Fabrizio, Palma, Marco & Cerrano, Carlo, 2020, Porifera from Ponta do Ouro (Mozambique), pp. 1-56 in European Journal of Taxonomy 698 on page 48, DOI: 10.5852/ejt.2020.698, http://zenodo.org/record/397851
Fig. 1 in Porifera from Ponta do Ouro (Mozambique)
No full textFig. 1. Map of the coast of Mozambique where Ponta do Ouro, the partial Marine Reserve and dive sites for sampling are located.Published as part of Calcinai, Barbara, Belfiore, Giuseppe, Pica, Daniela, Torsani, Fabrizio, Palma, Marco & Cerrano, Carlo, 2020, Porifera from Ponta do Ouro (Mozambique), pp. 1-56 in European Journal of Taxonomy 698 on page 3, DOI: 10.5852/ejt.2020.698, http://zenodo.org/record/397851
New insights into the symbiosis between Zanclea (Cnidaria, Hydrozoa) and scleractinians.
No full textFig. 15 in Porifera from Ponta do Ouro (Mozambique)
No full textFig. 15. Cliona grandis Samaai et al., 2019. A. Sponge in encrusting stage (β), PO64. B–D. Sponges in massive stage (γ), respectively PO22, IMG830 and PO27. E. Tylostyles. F. Magnification of the tylostyle head.Published as part of Calcinai, Barbara, Belfiore, Giuseppe, Pica, Daniela, Torsani, Fabrizio, Palma, Marco & Cerrano, Carlo, 2020, Porifera from Ponta do Ouro (Mozambique), pp. 1-56 in European Journal of Taxonomy 698 on page 29, DOI: 10.5852/ejt.2020.698, http://zenodo.org/record/397851
Genus Distichopora (Cnidaria, Hydrozoa): from primary cyclosystem to adult pore organization.
No full textFIGURE 33. Gelliodes hamata Thiele, 1903. A in Sponges associated with octocorals in the Indo-Pacific, with the description of four new species
No full textFIGURE 33. Gelliodes hamata Thiele, 1903. A, Sponge covering the basal stolons of Paratelesto rosea; B. Close up of the sponge; C–D, Ectosomal skeleton of an irregular, tangential network of spongin fibres; E–F, Choanosomal skeleton formed by irregular network of spongin fibres; G, Oxea; H, Flabellate sigma I; I, Sigma II.Published as part of Calcinai, Barbara, Bavestrello, Giorgio, Bertolino, Marco, Pica, Daniela, Wagner, Daniel & Cerrano, Carlo, 2013, Sponges associated with octocorals in the Indo-Pacific, with the description of four new species, pp. 1-61 in Zootaxa 3617 (1) on page 52, DOI: 10.11646/zootaxa.3617.1.1, http://zenodo.org/record/24815
Southern hemisphere deep-water stylasterid corals including a new species, Errina labrosa sp. n. (Cnidaria, Hydrozoa, Stylasteridae), with notes on some symbiotic scalpellids (Cirripedia, Thoracica, Scalpellidae)
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Spring composition of the macroalgal vegetation of a small offshore island in the north-western Mediterranean (Gallinara Island, Ligurian Sea)
Full text linkGallinara Island, a small island located 1.5 km off the shore of Liguria (Italy, north-western Mediterranean Sea) was included in a list of proposed Marine Protected Areas (MPA) in the early 90s. Since then, its benthic assemblages have been studied in detail and the main macrophytic communities have been mapped. A detailed assessment of its benthic macroalgal flora, however, has never been made. Gallinara was visited in the course of 5 consecutive years and its macroalgal flora was studied based on collections made by snorkelling and SCUBA diving. Overall, 141 macroalgal taxa were collected and identified (23 Chlorophyta, 94 Rhodophyta, 24 Ochrophyta); 91 of them represent new records for the island. One of the most notable new records is the non-indigenous red alga Womersleyella setacea, previously unreported from the island and widely distributed, particularly on the south-eastern shore. Observations made in the course of the surveys confirm the rarefaction of some large-sized brown algae (particularly Sargassum vulgare) but indicate also that others previously reported as rare (Cystoseira compressa, Dictyopteris polypodioides) are still common on the island
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