Schizotricha unifurcata Allman, 1883

Soto, Joan J. & Peña, Álvaro L., 2019, Benthic hydroids (Cnidaria, Hydrozoa) from the Weddell Sea (Antarctica), Zootaxa 4570 (1), pp. 1-78 : 45-46

Schizotricha unifurcata Allman, 1883

( Fig. 15 g–j)

Material examined. ANT XV/3: 48-5, one stem, c. 30 mm high; 48-33, few stems, up to 80 mm high, with developing gonothecae; 48-63, one stem, c. 75 mm high; 48-197, few stems, up to 50 mm high; 48-220, few stems, up to 60 mm high, with developing gonothecae; 48-276, several stems, up to 80 mm high, with gonothecae; ANT XVII/3: 111-9, one stem, c. 30 mm high; 111-19, several stems, up to 330 mm high, some on sponge, with gonothecae; ANT XXI/2: PS65/121, several stems, up to 100 mm high, with gonothecae; PS65/132, few stems, up to 95 mm high; PS65/274, few stems, up to 80 mm high.

Remarks. Some specimens differ from the re-description of the species provided by Peña Cantero et al. (1996) and the diagnoses of the species by Peña Cantero & Vervoort (2005). The materials from the stations ANT XV/ 3 48-5, 48-63, 48-220, ANT XXI/2 PS65/121, PS65/132 are unbranched, unlike our current knowledge of the species (see Peña Cantero & Vervoort 2005). However, according to the drawings provided by Allman (1883), the branching takes place in the very basal region of the colony. The fragmented condition of the material examined here could be masking this character. In the specimens mentioned above, there is a single nematotheca in the basal ahydrothecate internodes following hydrocladial apophyses ( Fig. 15h ) (but two in the basal ahydrothecate internodes following caulinar apophyses), unlike previous descriptions of the species, which reported two nematothecae in basal ahydrothecate internodes. No differences in number of nematothecae among basal ahydrothecate internodes according to location were mentioned by previous authors. Additionally, some hydrocladial internodes are provided with two consecutive hydrothecae ( Fig. 15j ), while a single one has been mentioned by previous contributions (e.g. Peña Cantero et al. 1996). This character variation has also been reported for Schizotricha turqueti Billard, 1906 (see Peña Cantero & Vervoort 2005). We have considered these observations as minor variations, and we assign all the material examined to Sc. unifurcata with confidence.

Ecology and distribution. Previously reported at depths from 15 ( Millard 1977) to 567 m ( Stechow 1925); present material between 62 to 417 m. Antarctic-Kerguélen distribution (Peña Cantero 1998).

Figures

FIGURE 15. a Aglaophenia baggins: hydrotheca. b–c Schizotricha glacialis: b forked hydrocladial internode; c unforked hydrocladial internode. d–f Sc. nana: d stem; e forked hydrocladial internode; f unforked hydrocladial internode. g–j Sc. unifurcata: g stem; h forked hydrocladial internode; i unforked hydrocladial internode; j internode with two hydrothecae.