Egmundella modesta Millard & Bouillon, 1975

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 : 495-496

Egmundella modesta Millard & Bouillon, 1975

( Fig. 4a ; Table 2)

Lovenella (?)— Millard & Bouillon, 1973: 42–43, fig. 5E–F.

Egmundella modesta Millard & Bouillon, 1975: 5–7 , fig. 1E–H; Vervoort, 2006: 224–225, figs. 7 no. 3; 8 no. 3; 9d–h.

Material examined. Western Sahara. MAROC-0611, stn MO235, 23º12′00″– 23º14′27″N, 17º11′16″– 17º12′27″W, 909–913 m, 27-XI-2006: a colony, 0.85 mm high, growing on Halecium sp. , without gonothecae .

Description. Colony stolonal, composed of hydrothecae and nematothecae arising from a filiform hydrorhiza. Hydrothecae borne on pedicels of varied length, though most are short, slender, generally smooth, occasionally with 2–5 basal annulations and sometimes a few irregularly-placed, additional annulations along its length, distally widening at junction with the corresponding theca, and there provided with a transverse, thin diaphragm. Hydrotheca deeply campanulate, tapering basally, walls almost parallel, aperture closed by a conical operculum, composed of 8–10 elongate, triangular flaps, independent from one another; flaps may be folded either inwards or outwards and, in this case, the rim is distinctly-marked. Nematothecae irregularly scattered, small, globular, borne on short pedicels, aperture apical, oval. No gonothecae observed.

Biology. Egmundella modesta has been reported so far growing on an unidentifiable hydroid fragment ( Vervoort 2006).

In our material, it was found growing on a species of Halecium .

Distribution. This species has previously been found in the Seychelles ( Millard & Bouillon 1973, as Lovenella sp. ; Millard & Bouillon 1975) and Mauritania ( Vervoort 2006). Its bathymetric distribution ranges from the littoral zone ( Millard & Bouillon 1975) to 1000 m ( Vervoort 2006).

Our material was found off Western Sahara at depths from 909 to 913 m.

Remarks. The material agrees in morphology with the holotype described by Millard & Bouillon (1975) from the Seychelles and with the CANCAP material of E. modesta studied by Vervoort (2006). In our material most of hydrothecae have short pedicels. However, some hydrothecae are larger in size, and have longer pedicels ( Fig 4a ). This feature was also described by Vervoort (2006), but we now provide more extensive measurements (see table 2).

Largest hydrothecae resemble those of E. grimaldii , but in that species the colonies form rhizocaulomic, stemlike structures, a character not observed in our material, where the hydrorhiza is composed of a single stolon growing on Halecium sp. Moreover, in E. grimaldii the hydrothecal pedicels are shorter and the nematothecae are larger.

After comparing material of both species collected during the MAROC surveys, we concluded that the present material is clearly different from E. grimaldii , while fitting well the descriptions of E. modesta found in the literature.

Figures

FIGURE 4. a, Egmundella modesta Millard & Bouillon, 1975, stn MO235, hydrorhiza with hydrothecae and nematothecae. b, Egmundella superba Stechow, 1921, stn MO49, hydrorhiza with hydrothecae and nematothecae. Scale bar: a–b = 1 mm.