Halecium tubatum, Watson, 2008

Watson, Jeanette E., 2008, Hydroids of the BANZARE expeditions, 1929 – 1931: the family Haleciidae (Hydrozoa, Leptothecata) from the Australian Antarctic Territory, Memoirs of Museum Victoria 65, pp. 165-178 : 174-175

Halecium tubatum sp. nov.

Figure 10A, B

Holotype, NMV F147470, Station 105, three microslides displaying several stems. Paratypes NMV F147471, Station 105, four microslides displaying colony. NMV F147472, one microslide displaying colony. NMVF 147477, Station 98, one microslide displaying colony. NMV F147480, Station 90, one microslide displaying colony. NMV F147481, Station 107, one microslide displaying colony .

Diagnosis. Hydrorhiza reptant on hydroid host, stolons thin, tubular, rugose to smooth. Hydrocauli fragile, variable in length, to 4 mm, unbranched; hydrocaulus above hydrorhiza weakly rugoseor with up to fourdeep annulations; hydrocaulus (pedicel) thereafter cylindrical, straight or weakly curved, walls smooth.

Pedicel bearing a single terminal hydrotheca; hydrotheca wide, bowl-shaped, walls flaring markedly from diaphragm to rim; rim circular, smooth, strongly outrolled, a row of desmocytes about halfway between diaphragm and rim. Afew secondary and succeeding hydrophores in linear row from diaphragm of hydrothecae; hydrophores widening to hydrotheca, a tumescence in perisarc above base.

Hydranths too few and too poorly preserved for description but possibly c. 20 tentacles.

Perisarc moderately thin throughout.

Gonotheca absent.

Measurements (μm) Remarks. Although the sample is infertile, and most of the microslide preparations heavily stained green, Halecium tubatum can nevertheless be seen to differ widely from all other known species of Halecium . It somewhat resembles Halecium tenellum Hincks, 1861 but that species is branched and the critical dimensions of the hydrotheca given by authors ( Ritchie 1907, Cornelius 1995, Vervoort 1966, Millard 1975) are much smaller than those of H. tubatum .

Etymology. The species is named for the trumpet-like hydrotheca

Figures

Figure 10.A, B.Halecium tubatum. A, hydrorhiza and two hydrothecae from holotype. B, hydrothecae enlarged. Scale bar: A, 0.5 mm. B, 0.3 mm.