Oswaldella bifurca Hartlaub 1904
- Dataset
- SEM study of species of Oswaldella Stechow, 1919 (Cnidaria, Hydrozoa, Kirchenpaueriidae), with an annotated checklist of the species of the genus
- Rank
- SPECIES
Classification
- kingdom
- Animalia
- phylum
- Cnidaria
- class
- Hydrozoa
- order
- Leptothecata
- family
- Kirchenpaueriidae
- genus
- Oswaldella
- species
- Oswaldella bifurca
description
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).
discussion
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).
materials_examined
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).