Gymnangium vegae ( Jäderholm, 1903 )

Watson, Jeanette E., 2018, Some Hydroids (Cnidaria, Hydrozoa) from the Great Australian Bight in the collection of the South Australian Museum, Zootaxa 4410 (1), pp. 1-34 : 24-25

Gymnangium vegae ( Jäderholm, 1903)

Figure 9G–J

Halicornaria vegae Jäderholm, 1903: 301 , pl. 15, figs 1–4.— Bale, 1914b: 185, pl. 36, figs 4, 5.— Jäderholm 1919: 26. Gymnangium vegae .— Vervoort & Watson, 2003: 261.— Bouillon et al., 2006: 284.

Haliaria vegae .— Stechow, 1923: 18.— Yamada, 1959: 83.— Hirohito, 1995: 291, fig. 102 c–e.

Material examined. SAM H2539, preserved material, one microslide ( SAM H2594). Near South Australia – Western Australia border, trawl, 180 m; coll: R. Southcott, 1/07/1988. SAM H2325, preserved material, south-west of Eucla, trawl, 178 m; coll: R. Southcott.

Description. Two fertile colonies the largest 16 cm tall, and fragments of another large colony; hydrorhiza a mass of hair-like stolons extending 20 mm up stem; stems heavily fascicled, polysphonic tubes straight, running to top of colony. Branches to 40 mm long, monosiphonic, gracefully arching dichotomously away from stem.

Hydrocladia short, bearing up to 10 hydrothecae, hydrocadial internodes slender with one very short indefinite septum below posterior adcauline wall of hydrotheca. Hydrotheca tubular, adcauline wall adnate to internode, walls almost parallel, abcauline wall slightly expanding behind margin, posterior of hydrotheca rounded with a very short inwardly directed bifurcate intrathecal septum. Margin slightly backwardly-oblique to hydrocladial axis, straight or with a pair of weak lobes in mid-region and a short, pointed anterior rostrum.

Median nematotheca short, digitate, narrowing distally, a short length free of hydrotheca, with two circular orifices, one terminal the other at junction with abcauline hydrothecal wall. Lateral nematotheca small, saccate, margin not reaching hydrothecal margin, orifice circular, excavated to hydothecal margin.

Gonotheca (probably male) cylindrical, on a short pedicel, apex closed by a flat transverse plug of tissue.

Hydrocladium

internode length 752–800 width at node 200–232 Hydrotheca

length, floor to margin 568–632 width at margin 336–360 Nematotheca

median, length 336–400 lateral, length 160–184 Gonotheca

length including pedicel 860–1060 distal width 440–480 Remarks. The s lender colonies have been bent during storage. Branching in the upper region varies from geniculate and dichotomous to triseriate as described by Bale (1914b). The mass of fibrous stolons and the flexuous colony indicates a habitat in a sedimentary substrate. Although seldom reported, Gymnangium vegae appears to be geographically widespread.

Distribution. Great Australian Bight, Japan.