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. 3 View Figure )

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–C View Figure ), and another one emerging through a ‘mamelon’, which may be little marked ( Fig. 3B View Figure ) or even absent.

Distinct node between cauline apophyses and hydrocladia ( Fig. 3B–C View Figure ). Up to third-order hydrocladia present ( Fig. 3A View Figure ). Hydrocladia with asymmetrical arrangement, with main primary hydrocladium giving rise to several second-order hydrocladia ( Fig. 3A View Figure ). Some of these giving rise to a third-order hydrocladium at their first hydrothecate internode ( Fig. 3A View Figure ). Hydrocladia heteromerously divided into an alternate series of athecate and hydrothecate internodes ( Fig. 3A View Figure ). Mesial-inferior nematophore emerging from distinct swelling at proximal third of internode ( Fig. 3D–F View Figure ) and provided with a scale-shaped nematotheca ( Fig. 3D, F View Figure ). Hydrotheca placed on distal half of hydrothecate internodes ( Fig. 3A, D–E View Figure ). 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–E View Figure ).

Immature gonothecae cone-shaped ( Fig. 3G View Figure ).

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. 3C View Figure ) 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