Hincksella formosa ( Fewkes, 1881 )

Galea, Horia R., 2013, New additions to the shallow-water hydroids (Cnidaria: Hydrozoa) of the French Lesser Antilles: Martinique, Zootaxa 3686 (1), pp. 1-50 : 25-26

Hincksella formosa ( Fewkes, 1881)

( Fig. 6 U–Z)

Sertularella formosa Fewkes, 1881: 130 .― Nutting, 1895: figs 2, 2A; 1904: 104, pl. 27 figs 2–4.― Fraser, 1944: 260, pl. 55 fig. 246.― Vervoort, 1959: 264, figs 27C, 29.

Sertularia integritheca Allman, 1888: 60 , pl. 29 figs 2, 2A.― Nutting, 1895: 88.― Versluys, 1899: 37. Sertularella hartlaubi Nutting, 1904: 104 , pl. 27 fig. 5.―Galea, 2009: 65, fig. 2J–L. Hincksella formosa ― Calder & Kirkendale, 2005: 484.

Material examined. Stn. 8, 25.i.2012, 12– 15 m, M052: numerous colonies and fragments 2.5–10 cm high, some with gonothecae (MHNG-INVE-82890); 27.i.2012, 9– 15 m, M061: two fertile colonies 4.0 and 7.5 cm, respectively (MHNG-INVE-82938). Stn. 14, 20.ii.2012, 10– 13 m, M231: numerous erect stems, 2–12 cm high, some bearing gonothecae (MHNG-INVE-82939).

Remarks. For a redescription of the trophosome, refer to Vervoort (1959). The gonotheca was described by Nutting (1904) and his account is generally accurate. However, the "four flapped membranous operculum" observed by him is not an anatomical structure, but rather the result of the distal perisarc sheet of the gonotheca ( Fig. 6 Y) rupturing, thus allowing the release of the gametes. The gonotheca is 2050–2195 µm long and 1035–1120 µm wide in middle, and is provided with 2–4 distal, blunt spines. One of its lateral sides is always concave ( Fig. 6 V, X), though not necessarily that adnate to the internode. Cnidome (not previously reported): 1) slender microbasic heteronemes, (6.9–7.4)×(2.6–2.9) µm; 2) slightly larger microbasic heteronemes, (7.7–8.2)×3.5 µm; 3) huge macrobasic mastigophores, (26.6–29.8)×(6.9–7.7) µm.

Geographical distribution. Widely distributed in the tropical eastern and western Atlantic, but also occurring in the tropical eastern Pacific: Brazil ( Allman 1888, as Sertularia integritheca ), Bahamas ( Nutting 1895, as S. integritheca ), Cuba ( Nutting 1904), Peru ( Nutting 1904, as Sertularella hartlaubi ), Ghana ( Vervoort 1959, as Sertularella formosa ). In the Caribbean, it was reported from Grenada and Martinique ( Fewkes 1881), Testigos ( Versluys 1899, as S. integritheca ), from an offshore locality between Jamaica and Haiti ( Nutting 1904, as S. hartlaubi ), and from Panama ( Calder & Kirkendale 2005).

Figures

FIGURE 6. A, B: Diphasia digitalis (Busk, 1852) ― stem internode in frontal (left) and lateral (right) views (A); optical cross section through internode at level of hydrothecal apertures (B). C – G, J – M: Sertularella calderi sp. nov. ― fragments of stem (C, D); hydrothecae (E) and aperture viewed from above (F); comparison of the hydrotheca (G) with those of S. fraseri Galea, 2010 a (H) and S. peculiaris Leloup, 1974 (I); male (J) and female (K) gonothecae; apertures of male (L) and female (M) gonothecae viewed laterally (below) and apically (above). N – P: Sertularelloides cylindritheca (Allman, 1888) ― internodes (N); lateral view of hydrotheca (O) with thickened internal ring of perisarc at base of apophysis (right), and frontal view of the latter (left); apical view of hydrotheca (P). Q – T: Thyroscyphus longicaulis Splettstösser, 1929 ― fragment of stem (Q); internode and hydrotheca (R); aperture (S); male (left) and female (right) gonothecae (T). U – Z: Hincksella formosa (Fewkes, 1881) ― hydrotheca (U); gonotheca seen laterally (V), and in optical cross section (X); aperture (Y). Scale bars: 10 µm (Z), 200 µm (F, L, M), 300 µm (P), 500 µm (A, B, E, G – I, O, S, U, Y), 1 mm (C, D, J, K, N, R, T, V, X), 4 mm (Q).