Oswaldella herwigi El Beshbeeshy, 2011

Cantero, A. L. Peña & Molinero, A. González, 2018, On several species of Oswaldella Stechow, 1919 (Cnidaria, Hydrozoa), including the description of a new species, Zootaxa 4457 (3), pp. 397-414: 402

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Oswaldella herwigi El Beshbeeshy, 2011


Oswaldella herwigi El Beshbeeshy, 2011 

( Fig. 3View FIGURE 3)

Oswaldella herwigi El Beshbeeshy, 1991: 259  –265, fig. 66 (nomen nudum); 2011: 197–201, fig. 66; Peña CanTerO et al., 1997: 344; Peña CanTerO & García CarrascOsa, 1998: 179; 1999: 214; Peña CanTerO & VerVOOrT, 1998: 36; 2004: 835–837, fig.

10; Peña CanTerO & Marques, 1999: 85; GOnzález MOlinerO & Peña CanTerO, 2015: 436; Miranda et al., 2016: 596 – 597.

Material examined. Patagonia 0 210, Stn DR 4, 20 February 2010, 41.983007 S, 57.974475 W, several stems up to 120 mm high.

Description. Monosiphonic, unbranched stems, up to 120 mm high, divided into internodes (one apophysis per internode). Cauline apophyses alternately arranged in one plane. Angle between cauline apophyses and stem ca. 45°. Cauline apophyses with an axillary nematophore emerging through a hole in perisarc ( Fig. 3B –CView FIGURE 3), and another one emerging through a ‘mamelon’, which may be little marked ( Fig. 3BView FIGURE 3) or even absent.

Distinct node between cauline apophyses and hydrocladia ( Fig. 3B –CView FIGURE 3). Up to third-order hydrocladia present ( Fig. 3AView FIGURE 3). Hydrocladia with asymmetrical arrangement, with main primary hydrocladium giving rise to several second-order hydrocladia ( Fig. 3AView FIGURE 3). Some of these giving rise to a third-order hydrocladium at their first hydrothecate internode ( Fig. 3AView FIGURE 3). Hydrocladia heteromerously divided into an alternate series of athecate and hydrothecate internodes ( Fig. 3AView FIGURE 3). Mesial-inferior nematophore emerging from distinct swelling at proximal third of internode ( Fig. 3D –FView FIGURE 3) and provided with a scale-shaped nematotheca ( Fig. 3D, FView FIGURE 3). Hydrotheca placed on distal half of hydrothecate internodes ( Fig. 3A, D –EView FIGURE 3). Hydrotheca low, about as high as wide. Abcauline hydrothecal wall straight or slightly convex. Adcauline hydrothecal wall with conspicuous free portion. Hydrothecal aperture circular, perpendicular to long axis of internode or abcaudally directed; rim even ( Fig. 3D –EView FIGURE 3).

Immature gonothecae cone-shaped ( Fig. 3GView FIGURE 3).

Remarks. According to Peña Cantero & Vervoort (2004) the ‘mamelon’ in Oswaldella herwigi  is provided with a distal conical structure not seen in the remaining species of the genus (see Fig. 10D in Peña Cantero & Vervoort 2004). In the material examined here, we did not observe that conical structure; ‘mamelons” observed were similar to those found in other species of Oswaldella  . However, we noticed that gonothecae might form on the cauline apophyses and, in some cases, directly from the ‘mamelon’. Very incipient gonothecae create a sort of structure ( Fig. 3CView FIGURE 3) that could be that observed by those authors using optical microscopy.

Oswaldella herwigi  is the only known species of the genus with heteromerous hydrocladial division, having alternating thecate and athecate internodes.

Distribution. Oswaldella herwigi  is the only species of the genus found outside Antarctic waters. It is considered endemic to the Patagonian region ( El Beshbeeshy 2011).














Oswaldella herwigi El Beshbeeshy, 2011

Cantero, A. L. Peña & Molinero, A. González 2018

Oswaldella herwigi

El Beshbeeshy, 1991 : 259