Two new species of Antarctic gorgonians (Octocorallia: Primnoidae) with a redescription of Thouarella laxa Versluys, 1906

Two new species of the genus Thouarella from Antarctic waters are described and illustrated from material collected on the Polarstern cruises ANT XVII/3 (EASIZ III), ANT XIX/5 (LAMPOS) and ANT XXI/2 (BENDEX). On the one hand, Thouarella viridis sp. nov. is placed in the subgenus Epithouarella due to the characteristic ornamentation of its marginal scales (the previously most recent species in this group was included by Ku¨kenthal in Zool Anz 33(1): 9–20, 1908). On the other hand, Thouarella minuta sp. nov. is included in subgenus Thouarella among the 14 species currently recognised, the main distinct feature being tiny polyps. Furthermore, a complete redescription is given of Thouarella laxa Versluys, 1906. Using the new technology available nowadays, such as images obtained with SEM, we provide accurate images of the polyps and sclerites. In addition, as a result of this study, T. laxa and its closest congener T. tydemani Versluys, 1906 are maintained as separate species, mainly due to their internal sculpture of body and coenenchymal scales

Four new species of thouarella (anthozoa: octocorallia: primnoidae) from antarctic waters

Four new Antarctic species of the genus Thouarella, all of them belonging to the subgenus Thouarella, are described and illustrated from material collected at the South Georgia and the South Sandwich Islands, and off Atka Bay (eastern Weddell Sea) on the Polarstern cruises ANT XIX/5 (LAMPOS), and ANT XXIV/2 (ANDEEP-SYSTCO). The study of our new taxa allows us to describe a wider variation in the number of the distal cycles of polyp scales, as well as the existence in the genus (and subgenus) of additional species with planar colonial morphologies. The new species are compared with their closest congeners

Revision and redescription of the species previously included in the genus Amphilaphis Studer and Wright in Studer, 1887 (Octocorallia: Primnoidae)

The taxonomy of the primnoid genus Amphilaphis Studer and Wright in Studer, 1887 has been in a confused state for a long time and a revision of the species included in that genus has become a necessity. We have revised and redescribed the species previously included in the genus using up-to-date technology, such as polyp and sclerite images obtained with scanning electron microscopy (SEM). As a result of this study, because the type species of Amphilaphis is actually a Thouarella species, we consider the genus Amphilaphis to be no longer valid. One of the species previously considered in Amphilaphis has a set of morphological characters that are not recognizable in any of the current primnoid genera. Primnocapsa n. gen. has a dichotomous branching pattern, polyps placed singly, in spirals around the branchlets, 8 opercular scales with the inner surface keeled and with 2 mounds basally and 8 marginal scales offset from the operculars. The new genus is described and illustrated. Moreover, one of the re-examined species has been included in a new subgenus, Faxiella n. subgen. of Plumarella Gray, 1870 because it has polyps placed in pairs. Finally, the remaining re-examined species have been included in the genus Thouarella Gray, 1870, one of the most specious primnoid genera

Life in extreme conditions : the paradox of Antarctic marine biodiversity

The study of pristine places is very important for learning about the state of the oceans before the impact of human beings. Due to the extreme environmental conditions of the Antarctic continental shelf ? its distance from other continents, depth, and the weight of the continental ice ? it offers us a great opportunity to better understand how a pristine ecosystem would normally be. In addition to a high level of biodiversity, Antarctic benthic organisms present patterns of demographic and spatial distribution that are different from the communities of the continental shelves in other seas and oceans of the world. This makes Antarctic benthic communities look, more than one might think, like the communities with the highest known biodiversity in the world

Pristine populations of habitat-forming gorgonian species on the Antarctic continental shelf

Declines in the abundance of long-lived and habitat-forming species on continental shelves have attracted particular attention given their importance to ecosystem structure and function of marine habitats. The study of undisturbed habitats defined as “pristine areas” is essential in creating a frame of reference for natural habitats free of human interference. Gorgonian species are one of the key structure-forming taxa in benthic communities on the Antarctic continental shelf. Current knowledge of the diversity, distribution and demography of this group is relatively limited in Antarctica. To overcome this lack of information we present original data on pristine and remote populations of gorgonians from the Weddell Sea, some of which display the largest colony sizes ever recorded in Antarctica. We assessed the distribution patterns of seven gorgonian species, a morphogroup and a family in front of the Filchner Ronne Ice Shelf (Weddell Sea) by means of quantitative analysis of video transects. Analysis of these videos showed a total of 3140 colonies of gorgonians with the highest abundance in the southern section and a significantly clumped distribution. This study contributes to the general knowledge of pristine areas of the continental shelf and identifies the eastern Weddell Sea as a hotspot for habitat-forming species

Digitogorgia brochi Zapata-Guardiola & López-González, 2010, sp. nov.

Digitogorgia brochi sp. nov. Figures 8–12 Thouarella (Euthouarella) brucei, Broch, 1965: 27 –28, pl. 4, fig. 11–13. Material examined. Holotype: NHM B 969, “Brategg” Expedition, “Tromso-Tral 2 ”, 54 º 43 ’S, 60 º 14 ’W, Burdwood Bank, SubAntarctic, 111.5 m depth, 0 9 March 1948. Description of the holotype. Fragment of a colony (Figure 8 A), probably a main side branch, of 16 cm in total height and about 4.5 cm in width, with simple branchlets (Figure 8 B) up to 3cm in length arising all around the branch forming a bottlebrush shape. Axis brown. Main side branch basal axis diameter 2.3 mm. Main stem basal axis diameter 2.9 mm. Polyps (Figure 9) on branchlets in whorls of 3, 4– 5 whorls per cm, directed upwards. Polyps relatively elongate, slightly clavate, about 1.6–2.2 mm in height and 0.6–0.8 mm in diameter. Polyp body with eight complete longitudinal rows of scales, those in adaxial rows slightly smaller. About 6–7 scales in each adaxial row (Figure 10 A) and 12–13 scales on each abaxial row (Figures 9 B, 10 C). Adaxial rows slightly disorganized basally, but without any reduction in number of rows (Figure 9). Accessory operculars (Figure 11 A) eight in number, 0.25–0.44 mm in height and 0.08–0.14 mm in width, more or less triangular and pointed. Proximal inner surface tuberculate, covering about 20–50 % of their length, distal inner surface smooth. Outer surface quite granular with several warts on the most proximal portion. Basal margin with digitate processes. Opercular scales (Figure 11 B) eight in number, 0.30–0.45 mm in height and 0.16–0.24 mm in width, more or less triangular or oval shaped. Proximal inner surface tuberculate, covering around half of their length, distal surface smooth without keel or thorn. Proximal outer surface granular with several warts on the most proximal part, distal portion quite smooth. Basal margin often with long digitate processes, free margin entire laterally but digitate apically. Marginal scales (Figure 11 C) eight in number, 0.33–0.43 mm in height and 0.23–0.46 mm in width, broad, oval shaped. Proximal inner surface tuberculate, covering up to 80 % of the length, distal inner surface smooth, without keel or thorn. Outer surface granular, most proximal part with several warts. Basal margin with long digitate processes, free margin entire laterally but digitate apically. Body scales (Figure 12 A) more-or-less oval to fan shape, 0.17–0.37 mm in height and 0.26–0.45 mm in width. Inner surface almost completely tuberculate, outer surface granular with several warts on the most proximal part. Free margin as in marginal scales. Coenenchymal sclerites (Figure 12 B) in two layers: outer layer with round, oval-shaped sclerites, 0.11– 0.24 mm in maximum length, inner surface tuberculate, outer surface granular or smooth, free margin entire or scalloped; inner layer with irregular tuberculate sclerites, 0.06–0.08 mm in maximum length. Geographic and bathymetric distribution. At present, Digitogorgia brochi sp. nov., has only been reported from Burdwood Bank, SubAntarctic (Figure 1), at a depth of 111.5 m. Etymology. This species is dedicated to Hjalmar Broch, in recognition of his contribution to our knowledge of octocorals. Remarks. The present material was initially identified by Broch (1965) as Thouarella brucei. This author had already found differences in the shape of the opercular and marginal scales between his specimen and the original description of Thomson’s and Ritchie’s species. Nevertheless, he attributed those differences to a possible contamination in Thomson’s and Ritchie’s sample, and placed his specimen in T. brucei. But it seems that Broch never saw any type specimens of T. brucei, as he only mentions the original description and drawings. The present study of a single specimen identified by Broch as Thouarella brucei from Burdwood Bank, and deposited at the NHM, shows a set of characters that is clearly different from that of the type material of T. brucei. This set of characters is: the polyps are arranged in whorls of three, the number of scales on each abaxial row is about 12 and distinct opercular and marginal scales are without a keel, while in T. brucei the polyps are singly placed in spirals around branchlets, the number of scales on each abaxial row is about 5 and opercular and marginal scales present a strong keel on their inner surface. Broch’s specimen, described above, has a bottlebrush colony shape, the scales are not reduced in the adaxial rows, there are eight marginal scales, without a keel, folding over the operculars and there are distinct, distal, pointed processes in opercular, marginal and body scales. Due to these characters it should be included in the genus Digitogorgia, as Digitogorgia brochi sp. nov. Till now the genus Digitogorgia only included one species, Digitogorgia kuekenthali. Digitogorgia kuekenthali and D. brochi differ in the number of scales in the abaxial row (8-9 scales in the former and 12-13 in the later), in the shape of the accessory opercular scales (more pointed in the former), the operculars (more elongate and multi-digitate in the former), and the marginals (with more developed and pointed processes in the latter). In general, the proximal, long processes in both polyp and coenenchymal sclerites and the presence of tubercles on the proximal outer surface are more pronounced in D. brochi.Published as part of Zapata-Guardiola, Rebeca & López-González, Pablo J., 2010, Redescription of Thouarella brucei Thomson and Ritchie, 1906 (Cnidaria: Octocorallia: Primnoidae) and description of two new Antarctic primnoid species, pp. 48-68 in Zootaxa 2616 on pages 57-63, DOI: 10.5281/zenodo.19791

Digitogorgia Zapata-Guardiola and Lopez-Gonzalez 2010

Genus Digitogorgia Zapata-Guardiola and López-González, 2010 Diagnosis (modified from the original description, modifications in bold). Primnoidae with bottlebrush colonies and simple branchlets. Polyps elongated, cylindrical, markedly curved upwards to the branch, and arranged in whorls. Accessory operculars eight in number, stick shaped, close to eight operculars. Marginal scales without thorn or keel, eight in number, folding over operculars. Opercular and marginal scales, with pointed digitations distally, attenuated in body scales. Body scales in eight complete longitudinal rows. Coenenchyme with two layers: outer layer of oval shaped scales, inner layer with irregular tuberculate sclerites. Remarks on diagnosis. During the study of Digitogorgia brochi sp. nov. we observed the presence of an additional inner layer of irregular tuberculate coenenchymal sclerites. Coenenchymal sclerites were described as a single layer of scales in the type species D. kuekenthali Zapata-Guardiola and López-González, 2010. After a re-examination of the coenenchyme of the holotype ZIZMH C 11740 and paratype USNM 1128575 (2 fragments as BEIM-CRO- 30 in Zapata-Guardiola and López-González, 2010 b: 317) of D. kuekenthali, an inner layer of irregular tuberculate sclerites (Figure 7) was also observed.Published as part of Zapata-Guardiola, Rebeca & López-González, Pablo J., 2010, Redescription of Thouarella brucei Thomson and Ritchie, 1906 (Cnidaria: Octocorallia: Primnoidae) and description of two new Antarctic primnoid species, pp. 48-68 in Zootaxa 2616 on pages 56-57, DOI: 10.5281/zenodo.19791