Filellum magnificum, Cantero & Svoboda & Vervoort, 2004

Cantero, A. L. Peña, Svoboda, A. & Vervoort, W., 2004, Antarctic hydroids (Cnidaria, Hydrozoa) of the families Campanulinidae, Lafoeidae and Campanulariidae from recent Antarctic expeditions with R. V. Polarstern, with the description of a new species, Journal of Natural History 38 (18), pp. 2269-2303 : 2287-2289

publication ID

https://doi.org/ 10.1080/00222930310001647361

persistent identifier

https://treatment.plazi.org/id/002E150C-FFC0-055A-FE43-FB0899E84E44

treatment provided by

Felipe

scientific name

Filellum magnificum
status

sp. nov.

Filellum magnificum View in CoL sp. nov.

( figures 2G, H View FIG , 5 View FIG ; table 1)

Material examined. ANT I-2 Stn 135, a few hydrothecae on Stegella lobata (RMNH-Coel. 30779); ANT II-4 Stn 474, numerous hydrothecae on Billardia subrufa (RMNH-Coel. 30788); ANT II-4 Stn 502, several hydrothecae on B. subrufa , with coppinia (holotype, RMNH-Coel. 30789); ANT VIII-5 Stn 16-481, several hydrothecae on spicules of a sponge (RMNH-Coel. 30802); ANT IX-3 Stn 158, several hydrothecae on B. subrufa (RMNH-Coel. 30806).

Description. Colony stolonal, composed of creeping stolons giving rise to partially sessile hydrothecae. Hydrotheca tubular, sock-shaped and adnate to substratum for just a tiny portion ( figure 2G, H View FIG ). Hydrothecal aperture circular; rim even and smooth, though indistinctly everted. Free part of hydrotheca directed upwards at a varied degree. Frequently with few, long renovations. Adnate part of hydrothecae provided with a few striae on dorsal side. Cnidome consisting of two size-classes of nematocysts (e.g. ANT II-4 Stn 502): small (6.5–7.262.9 M m) and occasional large (18.265.2 M m). In the material from ANT VIII-5 Stn 16- 481 only the small nematocysts were observed (5.9–7.262.6–3.3 M m).

Coppinia consisting of firmly adpressed gonothecae with defensive tubes ( figure 5A View FIG ). Defensive tubes situated on periphery of the group of gonothecae, but also arising amongst those gonothecae ( figure 5A View FIG ), and provided with large distal circular aperture. Gonothecal aperture circular, situated on a short and distinctly

everted, distal neck ( figure 5B, C View FIG ).

Remarks. Filellum magnificum sp. nov. is allied to F. antarcticum and F. serratum by the presence of striae, but it is clearly distinguishable by the larger size of the hydrothecae, especially the larger diameter of the hydrothecal aperture (cf. table 1). Filellum magnificum sp. nov. also shares with F. serratum the bottleshaped gonothecae, provided with a short and strongly everted distal neck bearing the aperture. However, they differ because in F. serratum the defensive tubes are closed, arise amongst the gonothecae and branch over them forming a protective canopy, whereas in F. magnificum sp. nov., the defensive tubes are provided with a distal aperture and, though some defensive tubes arise amongst the gonothecae, most of them are situated on the periphery of the mass of gonothecae like a fence, arching over the gonothecae. Moreover, in F. serratum the gonothecae are much shorter and slightly wider. On the other hand, F. magnificum sp. nov. also differs from F. antarcticum by the shape of the gonothecae, since in Hartlaub’s species they are deprived of a distal neck and the defensive tubes are always situated at the periphery of the gonothecal mass. Filellum magnificum sp. nov. also differs from F. antarcticum and F. serratum by the larger size of the nematocysts, especially concerning the larger size-class (cf. table 1).

Ecology and distribution. Filellum magnificum sp. nov. was collected at depths from 205 to 640 m. Fertile material was found in February. It has been found epibiotic, mainly on hydroids ( Billardia subrufa and Halecium sp. ), but also on sponges. Filellum magnificum sp. nov. originates from the south and east coasts of the Weddell Sea (off Ronne Ice Shelf, off Riiser-Larsen Ice Shelf and off Cape Norvegia, Princess Martha Coast).

Etymology. The specific name magnificum refers to the relatively large and conspicuous hydrothecae.

Kingdom

Animalia

Phylum

Cnidaria

Class

Hydrozoa

Order

Leptothecata

Family

Lafoeidae

Genus

Filellum

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