Taxonomic studies on some Indo‐West Pacific Phidoloporidae (Bryozoa: Cheilostomata)

Scanning electron microscopy study of Lars Silns cheilostome bryozoan type specimens in the historical collections of natural history museums in Sweden

The type specimens of 42 cheilostome bryozoan species introduced by Lars Siln between 1938 and 1954 and housed at three different Swedish institutions (the Swedish Museum of Natural History in Stockholm, the Biological Museum in Lund and the Museum of Evolution in Uppsala) are here revised using scanning electron microscopy, with two exceptions, for the first time. As a result of this revision, new morphological observations were made for some species, such as ooecia in Antropora erecta, a costal pseudopore in Jullienula hippocrepis, intracolonial variation in the number of intracostal windows in Costaticella gisleni, and oral spines in Triphyllozoon mauritzoni. Some other observations confirmed the presence of structures/polymorphs in type material that had previously only been noted in non-type specimens, such as spinose interzooidal kenozooids in Retevirgula triangulata and putative brooding zooids in Bugulina kiuschiuensis. Structures originally interpreted as hydroid tube openings on the dorsal side of Triphyllozoon microstigmatum were confirmed to be avicularia, while the supposed kenozooidal attachment rootlet of Fedora nodosa might be the polypide tube of a coronate scyphozoan. In addition, the original combination Heliodoma goesi is here reinstated after Lagaaij assigned the species to Setosellina in 1963. The following new combinations are also proposed: Labioporella aviculifera for Siphonoporella aviculifera; Mangana canui and Mangana incrustata for Callopora canui and Tegella incrustata, respectively; Sphaerulobryozoon ovum for Fedora ovum. Lectotypes were selected when appropriate. This work clarifies the exact identity of some species that have never been recorded after their first description, such as Stylopoma magnovicellata and three species of Triphyllozoon, and contributes to the current increasing effort to digitize historical key specimens in natural history museum collections.

Morphospecies and molecular diversity of ‘lace corals’: the genus Reteporella (Bryozoa: Cheilostomatida) in the central North Atlantic Azores Archipelago

Background

As in most bryozoans, taxonomy and systematics of species in the genus Reteporella Busk, 1884 (family Phidoloporidae) has hitherto almost exclusively been based on morphological characters. From the central North Atlantic Azores Archipelago, nine Reteporella species have historically been reported, none of which have as yet been revised. Aiming to characterise the diversity and biogeographic distribution of Azorean Reteporella species, phylogenetic reconstructions were conducted on a dataset of 103 Azorean Reteporella specimens, based on the markers cytochrome C oxidase subunit 1, small and large ribosomal RNA subunits. Morphological identification was based on scanning electron microscopy and complemented the molecular inferences.

Results

Our results reveal two genetically distinct Azorean Reteporella clades, paraphyletic to eastern Atlantic and Mediterranean taxa. Moreover, an overall concordance between morphological and molecular species can be shown, and the actual bryozoan diversity in the Azores is greater than previously acknowledged as the dataset comprises three historically reported species and four putative new taxa, all of which are likely to be endemic. The inclusion of Mediterranean Reteporella specimens also revealed new species in the Adriatic and Ligurian Sea, whilst the inclusion of additional phidoloporid taxa hints at the non-monophyly of the genus Reteporella.

Conclusion

Being the first detailed genetic study on the genus Reteporella, the high divergence levels inferred within the genus Reteporella and family Phidoloporidae calls for the need of further revision. Nevertheless, the overall concordance between morphospecies and COI data suggest the potential adequacy of a 3% cut-off to distinguish Reteporella species. The discovery of new species in the remote Azores Archipelago as well as in the well-studied Mediterranean Sea indicates a general underestimation of bryozoan diversity. This study constitutes yet another example of the importance of integrative taxonomical approaches on understudied taxa, contributing to cataloguing genetic and morphological diversity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12862-022-02080-z.

Influence of depth on bryozoan richness and distribution from the continental shelf of the northern coast of Bahia State, north-eastern Brazil

Biological and abiotic processes influence ecosystem structure and species distribution. For bryozoan assemblages, depth, substratum and habitat structure are among the main factors influencing their distribution. Ecological studies on bryozoan fauna from Brazil are scarce and factors affecting the distribution and/or diversity of this common group are obscure. Here we attempted to verify the influence of bathymetry on bryozoan richness on the north shore of Bahia State, north-eastern Brazil. We identified 57 bryozoan taxa, comprising 35 families and 50 genera, all belonging to the Cheilostomata. Retevirgula multipunctata Winston, Vieira & Woollacott, 2014 and Tetraplaria dichotoma (Osburn, 1914) and the genus Aimulosia Jullien, 1888 were recorded for the first time from Bahia State. Species growing as encrusting sheets were dominant at all depths. There was a significant difference in richness among samples at different depths, with highest values of richness at 40 meters (Kruskal-Wallis Test). Analysis of similarities revealed a significant difference among the bryozoan assemblages, mainly when comparing assemblages from 10 and 20 meters with deeper ones. Also, shallower assemblages composition varied much than assemblages from 30 and 40 meters. Since depth is a proxy for several environmental parameters, further studies are needed to identify other factors influencing bryozoan distribution.