Oswaldella bifurca Hartlaub, 1904

Molinero, A. González & Peña Cantero, A. L., 2015, SEM study of species of Oswaldella Stechow, 1919 (Cnidaria, Hydrozoa, Kirchenpaueriidae), with an annotated checklist of the species of the genus, Zootaxa 4052 (4), pp. 401-441 : 403

publication ID	https://doi.org/ 10.11646/zootaxa.4052.4.1
publication LSID	lsid:zoobank.org:pub:47EF6E9D-9064-4899-B3DD-276FF7C969EB
DOI	https://doi.org/10.5281/zenodo.6107441
persistent identifier	https://treatment.plazi.org/id/03C287C6-2809-7C14-D4F4-89A82EDC7E84
treatment provided by	Plazi
scientific name	Oswaldella bifurca Hartlaub, 1904
status

Treatment

Oswaldella bifurca Hartlaub, 1904 View in CoL

( Figs 1 View FIGURE 1 , 16 View FIGURE 16 A, 17A, 19A)

Material examined. United States Antarctic Research Program ( USARP): Stn 32/2095, Eltanin, 3 February 1968, 76°04’– 76°05’S, 164°46’– 164°51’W (Ross Sea, center of sea), 513–550 m ( USNM 1003302).

Description. Monosiphonic, usually unbranched stems, up to 60 mm high, divided into internodes. Angle between cauline apophyses and stem ca. 70°. Cauline apophyses with one or two axillary nematophores emerging through simple perisarc holes ( Fig. 1 View FIGURE 1 B–C).

Hydrocladia much branched ( Fig. 1 View FIGURE 1 A); branching symmetrical, up to the fourth-order. First hydrocladial internode bifurcated, with two similar prongs ( Fig. 1 View FIGURE 1 A–B). Mesial superior nematophore emerging above adcauline hydrothecal wall. Mesial inferior nematophore located on a distinct elevation at lower third of internode; without nematotheca ( Fig. 1 View FIGURE 1 D–F). Distal hydrocladial internodes with sharp distal end ( Fig. 1 View FIGURE 1 A).

Hydrothecae placed on basal half or third of hydrocladial internodes. Hydrotheca low, about as high as wide. Adcauline hydrothecal wall either completely adnate to internode ( Fig. 1 View FIGURE 1 D) or with tiny free portion ( Fig. 1 View FIGURE 1 E). Abcauline wall roughly straight. Hydrothecal aperture usually circular ( Fig. 1 View FIGURE 1 E), although frequently frontally depressed ( Fig. 1 View FIGURE 1 D); rim usually rising laterally.

Gonothecae immature, inverted cone-shaped ( Fig. 1 View FIGURE 1 A, G).

Remarks. Peña Cantero & Vervoort (2004) already stated that the number of axillary nematophores on the cauline apophyses was variable, finding apophyses with a single axillary nematophore and others with two, even on the same stem. We have also observed that variability and, as those authors indicated, there is a clear tendency in the axillary nematophores to coalesce ( Fig. 1 View FIGURE 1 C).