Egmundella grimaldii Leloup, 1940

Gil, Marta & Ramil, Fran, 2023, The genera Egmundella Stechow, 1921 and Cyclocanna Bigelow, 1918 (Cnidaria, Hydrozoa) in waters of Northwest Africa, Zootaxa 5264 (4), pp. 490-504 : 492-495

Egmundella grimaldii Leloup, 1940

( Figs. 2 , 3 ; Table 1)

Egmundella grimaldii Leloup, 1940: 7 , pl. I fig.3.

Material examined. Morocco. CCLME 2012-404 , stn GR- 50, 30º34′12′′N, 9º46′36′′W, 30 m, 05-VII-2012: a colony without gonothecae.

MAROC-0411, stn MO39, 34º35′23″N, 6º30′33″W, 582 m, 26-XI-2004: a colony, 16 mm high, without gonothecae.

MAROC-0411, stn MO51, 34º06′43″– 34º05′59″N, 7º29′42″– 7º31′40″W, 722 m, 30-XI-2004: a colony, 35 mm high, without gonothecae.

MAROC-0411, stn MO53, 34º02′47″– 34º01′47″N, 8º00′00″– 8º01′44″W, 641–663 m, 30-XI-2004: four colonies, 10–38 mm high, one growing on Sertularella gayi , all without gonothecae.

Western Sahara. MAROC-0611, stn MO263, 24º35′26″– 24º38′23″N, 16º26′36″– 16º25′36″W, 410 m, 5-XII-2006: five colonies, 5–29 mm high, one growing on a bivalve, one on the ophiuroid Ophiacantha abyssicola ; one colony with a gonotheca .

Description. Colonies erect with rhizocaulomic hydrorhiza, becoming simple distally. Hydrothecae, nematothecae and the singly occurring gonotheca arising perpendicularly to the hydrorhiza. Hydrothecae borne on short, smooth pedicels; deeply campanulate, tapering basally, and there provided with a transverse, thing diaphragm; walls parallel, widening distally; rim well-marked, aperture closed by a conical operculum composed of 13–15 elongate, triangular flaps, not connected between them, and folded either inwards or outwards. Nematothecae given off irregularly among the hydrothecae; globular, borne on moderately-long pedicels, aperture distal, circular.

Gonotheca short-pedicellate, fan-shaped, strongly flattened “dorso-ventrally”, aperture distal, large, spanning from one side to the other ( Fig. 2e , 3 ); margin irregularly serrated, possibly resulting from rupture of the perisarc at maturity; distal part of the walls with numerous longitudinal ridges ( Fig. 3 ).

Biology. Egmundella grimaldii has been found growing on a campanulariid hydroid ( Leloup 1940).

In our material, one colony was found growing on Sertularella gayi ( Lamouroux, 1821) , one on a bivalve shell, and one on an ophiuran. A fertile colony was found in December.

Distribution. This species was previously found only once, by Leloup (1940), in the Bay of Biscay, between 748 and 1262 m.

Our material was found off both Morocco and Western Sahara at depths from 30 to 722 m.

Remarks. This is the first time this species has been found since its original description ( Leloup 1940), and our report also represents the first account of its gonotheca. The measurements of our material (see table 1) agree with those provided by Leloup (1940). The large size of the hydrothecae and their short pedicels are specific characters, allowing us to distinguish it from C. producta .

Egmundella grimaldii resembles in the shape of colonies to those of E.fasciculata Fraser,1942 ,from Massachusetts, USA. Nevertheless, there are several morphological characters which allow their specific differentiation. The latter is distally ramified, its nematothecae are borne on both the hydrorhiza and hydrothecal pedicels, and the hydrothecal aperture is closed by an operculum composed of 8–10 flaps. None of these features were observed in our material; moreover, the opercula of our hydrothecae are composed of a higher number of flaps.

Schuchert (2016) noted that the hydroid of E. grimaldii is similar to that of Cyclocanna producta (G.O. Sars, 1874) [as E. producta in his paper], and stressed the need for the study of new material to evaluate whether it is a mere variant of C. producta (see below). Our material shows the same diagnostic characters as those of the holotype, and the presence of a fertile specimen supports its specific validity. Despite the gonothecae of both species being quite similar in shape and size, they nevertheless differ in the presence of transversal and basal undulations in C. producta ( Schuchert 2016: 222) , versus longitudinal and distal ridges in the present species. In addition, comparison of the present material with colonies of C. producta , collected from the same study area, convinced us that they are distinct species (see below).

The morphological similarities between the gonothecae of E. grimaldii and C. producta suggest that both species could be congeneric. Nevertheless, and like Schuchert (2016), we considered necessary to study additional fertile material, including molecular studies in order to clarify its taxonomic position.

Figures

FIGURE 2. Egmundella grimaldii Leloup, 1940. a–c, stn GR-50; a, part of rhizocaulomic hydrorhiza with hydrothecae and nematothecae; b, hydrothecae; c, nematothecae. d–e, stn MO263; d, part of rhizocaulomic hydrorhiza with hydrotheca and nematothecae; e, gonotheca on hydrorhiza. Scale bar: a = 0.5 mm; b = 1 mm; c = 0.2 mm; d–e = 0.5 mm.

FIGURE 3. Egmundella grimaldii Leloup, 1940. a–c, stn MO263, a, frontal view of a gonotheca; b, lateral view of (the same) gonotheca and some nematothecae on hydrorhiza; c, lateral view of gonotheca, detail of longitudinal ridges. Scale bar: a–c = 0.5 mm.