Acryptolaria sp.

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 : 2281-2285

Acryptolaria sp. ( figure 2A, B )

Material examined. ANT II- 4 Stn 450, one stem ca 115 mm high (RMNH- Coel. 30777); ANT IX- 3 Stn 207, a few stems up to 120 mm high, the largest with coppinia (RMNH-Coel. 30778).

Description. Erect, polysiphonic stems up to 120 mm high. Branches up to fifth order observed. Branching approximately in one plane, usually alternate; in ANT II- 4 Stn 450 with some anastomoses. Hydrothecae alternately arranged approximately in one plane and partially overlapping. Hydrotheca ( figure 2A, B ) almost completely cyclindrical, but diameter distinctly decreasing at proximal part (145–177 M m diameter at base). Hydrotheca curved outwards, with one-quarter to one-half of its adcauline wall free; 419–693 M m and 1127–1369 M m length of free and adnate parts, respectively. Abcauline wall concave, especially at distal half, 1336–1562 M m long; adcauline wall convex, except the basalmost part, 1578–1820 M m long. Hydrothecal aperture circular (274–290 M m diameter); rim even and sometimes provided with a few short renovations. Cnidome composed of two kinds of nematocysts: small and large unidentified nematocysts (18–2166.5–7.5 M m).

Female coppinia fusiform, consisting of gonothecae closely set together around stem or main branches. Coppinia deprived of defensive tubes. Gonotheca fusiform, with a funnel-shaped aperture.

Remarks. Our material resembles several species described in Acryptolaria [e.g. A. conferta (Allman, 1877) ]. However, it is undesirable to assign it to any of the known species of the genus until a revision of the genus has been made and information concerning the cnidome has been provided.

Ecology and distribution. Our material originates from depths between 208 and 450 m. Acryptolaria sp. is used as substratum by other hydroids ( Billardia subrufa and Lafoea gaussica ). It was found with coppinia in March. It was collected in the Weddell Sea area (off Ronne Ice Shelf and off Fimbul Ice Shelf, Princess Astrid Coast).

Genus Filellum Hincks, 1868

Filellum antarcticum ( Hartlaub, 1904)

( figures 2C–F , 3 , 4 ; table 1) Lafoea antarctica Hartlaub, 1904: 11 , pl. 2 figure 2 ; Vanhöffen, 1910: 311, figure 31. Reticularia antarctica: Totton, 1930: 160–161 , figure 17. Filellum antarcticum: Millard, 1964: 10 ; 1975: 177, figure 58G–H; 1978: 192;

Bouillon et al., 1995: 52; Peña Cantero et al., 1998: 300–301.

Material examined. Polarstern material: ANT II-4 Stn 310, several hydrothecae on Billardia subrufa , with coppinia (RMNH-Coel. 30782); ANT II-4 Stn 341, numerous hydrothecae on B. subrufa and Stegella lobata , with coppinia (RMNH-Coel. 30783); ANT II-4 Stn 438, numerous hydrothecae on B. subrufa , with coppinia (RMNH-Coel. 30785); ANT II-4 Stn 474, numerous hydrothecae on B. subrufa , with coppinia (RMNH-Coel. 30788);?ANT II-4 Stn 524, numerous hydrothecae on Halecium sp. , with coppinia (RMNH-Coel. 30790); ANT VIII-5 Stn 16-399, several hydrothecae on B. subrufa , with coppinia (RMNH- Coel. 30794); ANT VIII-5 Stn 16-405, numerous hydrothecae on B. subrufa ,? Opercularella belgicae , and axis of gorgonian, with coppinia (RMNH-Coel. 30796); ANT VIII-5 Stn 16-456, a few hydrothecae on B. subrufa , with coppinia (RMNH-Coel. 30816); ANT VIII-5 Stn 16-459, several hydrothecae on B. subrufa , with coppinia (RMNH-Coel. 30799); ANT VIII-5 Stn 16-486, several hydrothecae on B. subrufa , with coppinia (RMNH-Coel. 30803); ANT IX-3 Stn 135, numerous hydrothecae on B. subrufa , with coppinia (RMNH-Coel. 30805).

Deutschen Southpolar Expedition: Gauss Station , 65 ‡ 21’S 86 ‡ 06’E, 385 m depth. Museum für Naturkunde der Humboldt-Universität zu Berlin (neotype, ZMB Cni 14222) .

Description. Stolonal colonies composed of stolons creeping on substratum and giving rise to sock-shaped hydrothecae ( figure 2E, F ), adnate to substratum to a varied degree. Adnate part of hydrothecae provided with striae on dorsal side; striation highly variable. Hydrothecal aperture circular, rim even. Cnidome composed of two kinds of nematocysts, small (5.2–5.962.6–2.9 M m) and large ones (11.7–14.365.2–5.9 M m).

Coppinia composed of a set of firmly adpressed gonothecae surrounded by a fence of long defensive tubes usually curved towards the centre of the gonothecal mass in such a way that they constitute a nest or corbula ( figure 4A, C, D ). Defensive tubes forked or unforked, provided with distal, circular aperture ( figure 4A–D ). Gonotheca tubular, basally truncated and with a distal, unraised, circular aperture ( figure 4E, F ), usually on a slightly raised, cone-shaped part. Eggs remaining on gonothecae, immersed in a sort of nourishing mass.

Remarks. The type material of Lafoea antarctica Hartlaub, 1904 is lost, so we found it necessary to indicate a neotype for this species. Since Vanhöffen (1910) was the first author to describe fertile material of this species, we have chosen his material as the neotype for Filellum antarcticum (ZMB Cni 14222).

Vanhöffen’s (1910) material consists of stolonal colonies formed by stolons that creep on the substratum and irregularly give rise to hydrothecae. Most hydrothecae are sock-shaped with a small portion adnate to the substratum ( figure 2C ); a few hydrothecae, however, are completely free ( figure 2D ). The free part of the hydrotheca is upwardly directed to a varied degree. The hydrothecae are slightly wider at aperture. The hydrothecal aperture is circular, the rim even, usually with few, long renovations. The dorsal portion of the adnate part of hydrotheca is provided with a few striae. The cnidome is composed of two sorts

Figures

FIG. 2. (A, B) Acryptolaria sp., hydrothecae; (C–F) Filellum antarcticum (Hartlaub, 1904), hydrothecae; (G, H) Filellum magnificum sp. nov., hydrothecae. (A from ANT II-4 Stn 450; B from ANT IX-3 Stn 207; C, D from neotype; E from ANT VIII-5 Stn 16-403; F, H from ANT VIII-5 Stn 16-481; G from ANT II-4 Stn 502.) Scale bar: 500 Mm (A, B); 200 Mm (C–H).

FIG. 3. Filellum antarcticum (Hartlaub, 1904). (A) General view of a dish-shaped coppinia; (B) detail of the two fused, dish-shaped structures protecting gonothecae; (C) detail of unforked defensive tubes; (D) egg; (E) egg and gonothecal apertures; (F) detail of gonothecal aperture. (All photographs from neotype.).

FIG. 4. Filellum antarcticum (Hartlaub, 1904) (continued). (A) General view of a coppinia; (B) detail of defensive tubes; (C) dorsal view of a coppinia with long defensive tubes; (D) lateral view; (E, F) gonothecal apertures. (A, B from ANT VIII-5 Stn 16-405; C–F from ANT VIII-5 Stn 16-399.).