Halecium marocanum Billard, 1934

Gil, Marta & Ramil, Fran, 2025, Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau, Zootaxa 5577 (1), pp. 1-89 : 42-43

Halecium marocanum Billard, 1934 nov. status

( Fig. 7E–F )

Halecium Sibogae marocanum Billard, 1934: 229 , fig. 2. Halecium sibogae var. marocanum : Patriti, 1970: 25, fig. 23. Halecium sibogae marocanum : Ramil & Vervoort, 1992a: 86–90, figs 21A–E, 22a–b.—Medel et al., 1998: 39–41, fig. 5.—

Ramil et al., 1998: 7–8, fig. 1.— Medel & Vervoort, 2000: 21–23, fig. 5.— Peña Cantero & García Carrascosa, 2002: 74–75,

fig. 15.— Vervoort, 2006: 254.— Gil et al., 2020: 427–428.

Material examined. BISSAU-0810, stn BS131, 11º34'07"– 11º33'13"N, 17º11'25"– 17º11'31"W, 102–103 m, 23-X-2008: one colony growing on a worm tube, without gonothecae; substrate unknown.

BISSAU-0810, stn BS191, 10º18'25"– 10º19'20"N, 16º08'47"– 16º08'47"W, 24–25 m, 3-XI-2008: 320 colonies (90 with male and female gonothecae), up to 6 mm high, of which 101 growing on Idiellana pristis , 54 on bryozoans, 35 on Eudendrium capillare , 23 on Diphasia digitalis , 15 on unidentified hydroids, 10 on Tridentata loculosa , seven on Garveia nutans , five on Bimeria vestita , five on Tridentata turbinata , four on Halecium sp. , two on Dynamena disticha , two on Thyroscyphus marginatus , one on Eudendrium ramosum , one on Halecium delicatulum , one on Tridentata marginata and one on Clytia gracilis .

BISSAU-0810, stn BS192, 10º19'30"– 10º20'15"N, 16º10'27"– 16º10'59"W, 24 m, 3-XI-2008: one colony without gonothecae, growing on Idiellana pristis .

BISSAU-0810, stn BS193, 10º21'13"– 10º21'51"N, 16º10'17"– 16º10'56"W, 20–21 m, 3-XI-2008: one colony without gonothecae, growing on Idiellana pristis .

BISSAU-0810, stn BS195, 10º22'44"– 10º23'22"N, 16º15'37"– 16º16'18"W, 29 m, 3-XI-2008: one colony without gonothecae, growing on a bryozoan.

Remarks. Halecium sibogae marocanum was described from Morocco by Billard (1934), who already noted some morphological differences with his Indonesian Halecium sibogae Billard, 1929 . In addition to some differences in the size of the hydrothecae between the species and the subspecies (see Ramil & Vervoort 1992a: 88), he also noted longer internodes, larger primary hydranthophores and hydrothecae with a more everted rim in H. sibogae marocanum . Also, the internode arrangement in the latter seems to be more geniculate than that observed in H. sibogae ( Billard 1934: 229) .

In recent years, the description of fertile materials revealed new differences between the gonothecae of the two forms. In H. sibogae marocanum the male gonothecae are globular, smooth-walled, with two more or less developed apical elevations, between which is situated the aperture at the end of a short cone ( Ramil & Vervoort 1992a). The female gonothecae have an oval-conical shape and also show the same characteristic opening flanked by two elevations ( Medel & Vervoort 2000, fig. 15c; Peña Cantero & García Carrascosa 2002, fig. 15f). On the other hand, in H. sibogae , gonothecae of both sexes variably develop triangular crests along their perimeter, they are slightly compressed fronto-dorsally, and appear to be composed of two distinct valves fused along their perimeter (Galea, personal communication).

Another difference between these two forms is their geographical distribution: H. sibogae marocanum has an Atlantic-Mediterranean occurrence ( Billard 1934; Ramil & Vervoort 1992a; Gil et al. 2020), while H. sibogae is restricted to the Pacific and Indian Oceans ( Billard 1929; Gibbons & Rayland 1989; Galea, personal communication).

Therefore, due to the morphological differences mentioned above, and taking into account the absence of intermediate forms and the large distributional gap between the two morphotypes, we believe that these are solid arguments to raise the subspecies H. sibogae marocanum to full species level, as Halecium marocanum Billard, 1934 nov. status.

Our finding represents the first record of this species for Guinea-Bissau.

Biology. Halecium marocanum has been found growing on a wide variety of substrates ( Gil et al. 2020, as H. sibogae marocanum ). In the northern hemisphere, fertile material has been reported in March, June–August ( Peña Cantero & García Carrascosa 2002, as H. sibogae marocanum ), November ( Gil et al. 2020) and December ( Gil & Ramil 2017a, as H. sibogae marocanum ).

Our colonies were found growing on hydroids, worm tubes and bryozoans. Gonothecae were found in November.

Distribution. This species has an Atlantic-Mediterranean distribution ( Peña Cantero & García Carrascosa 2002; Gil et al. 2020). In West Africa, it was recorded from Morocco ( Patriti 1970, as Halecium sibogae var. marocanum ; Ramil & Vervoort 1992a; Vervoort 2006, both as H. sibogae marocanum ) to the Cape Verde Islands ( Medel & Vervoort 2000, as H. sibogae marocanum ). Its bathymetric distribution ranges from 16 ( Peña Cantero & García Carrascosa 2002) to 756 m ( Ramil et al. 1998, as H. sibogae marocanum ).

Our material was collected at depths between 20–103 m.

Figures

FIGURE 7. A. Halecium halecinum (Linnaeus, 1758) (stn BS147), portion of colony with male gonotheca. B. Halecium lankesteri (Bourne, 1890) (stn BS193), portion of colony. C–D. Halecium liouvillei Billard, 1934 (stn BS192); portion of colony (C); female gonotheca (D). E–F. Halecium marocanum Billard, 1934 (stn BS191); portion of colony (E); gonotheca (F). Scales: a–f, 0.5 mm.