Oswaldella bifurca Hartlaub 1904

• Main Authors: Molinero, A. González, Peña Cantero, A. L.
• Format: Other/Unknown Material
• Language: unknown
• Published: 2015
• Subjects: Biodiversity; Taxonomy; Animalia; Cnidaria; Hydrozoa; Leptothecata; Kirchenpaueriidae; Oswaldella; Oswaldella bifurca; Antarctic; Ross Sea; Molinero; Antarc*
• Online Access: https://zenodo.org/record/6107441; https://doi.org/10.5281/zenodo.6107441

Oswaldella bifurca Hartlaub, 1904 (Figs 1, 16 A, 17 A, 19 A) 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 B–C). Hydrocladia much branched (Fig. 1 A); branching symmetrical, up to the fourth-order. First hydrocladial internode bifurcated, with two similar prongs (Fig. 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 D–F). Distal hydrocladial internodes with sharp distal end (Fig. 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 D) or with tiny free portion (Fig. 1 E). Abcauline wall roughly straight. Hydrothecal aperture usually circular (Fig. 1 E), although frequently frontally depressed (Fig. 1 D); rim usually rising laterally. Gonothecae immature, inverted cone-shaped (Fig. 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 C). Published as part of 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, pp. 401-441 in Zootaxa 4052 (4) on page 403, ...