Aglaophenia sinuosa Bale, 1888

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 : 19-20

Aglaophenia sinuosa Bale, 1888

Figure 8B–F

Aglaophenia sinuosa Bale, 1888: 790 , pl. 21, figs 1, 2.— Jäderholm, 1917: 19, pl. 2, fig. 9.— Stranks, 1993: 13.— Watson, 1994: 67.— Vervoort & Watson, 2003: 278, figs 65 E, F, 66 A–E.

Aglophenia bakeri Bale, 1919: 353 , pl. 17, figs 7, 8.

Material examined. SAM H2334, preserved material; two microslides (SAM H2590, H2591). PIRSA Stn BBMP3.

Description. Flabellate colony of eight stems to 60 mm long with one corbula, hydrorhiza reptant on worm tube. Stems monosiphonic, subdichotomously branched once or twice, lower stem region and base of branches ahydrocladiate. Stem and branch internodes short, stout, nodes indistinct, transverse to weakly oblique. Hydrocladia to 10 mm long.

Hydrotheca short, saccate, set at an angle of 20–30° to hydrocladial axis, widening from base to margin, abcauline wall straight, adcauline wall adnate to hydrocladium, shallowly convex, two intrathecal septa, one short, oblique in hydrotheca from near posterior base, the other long, strong, curving slightly forwards more than halfway into hydrotheca below base of median nematotheca, terminating in a strong twist of perisarc. Hydrothecal margin with a pointed bifid anterior rostrum flanked by three pairs of bluntly pointed cusps. Median nematotheca tubular, short, terminating in a short free section behind intrathecal septum, terminal orifice circular. Lateral nematotheca large, saccate, orifice circular, excavated back to hydrotheca, a short septum passing into nematotheca about halfway along adcauline wall. Two cauline nematothecae, one below hydrocladium, the other opposite axil of apophysis, body almost divided in two by septum, each section saccate with a small outwardly facing almost circular orifice.

Corbula closed, with up to 10 leaflets, replacing a hydrocladium, first hydrocladial internode hydrothecate, leaflet with six to eight saccate marginal nematothecae with a keyhole-shaped orifice.

Colour, honey brown (preserved material).

Remarks. The material conforms to description by Bale (1888) of A. sinuosa and measurements given by Jäderholm (1917) and Vervoort & Watson (2003). The species may show reversals of 180° along sections of the hydrocaulus so that groups of hydrocladia face alternately to the back and front. This phenomenom may occur only in large specimens as the present material shows no such reversals.

The Bale collection in Museum Victoria contains six microslides (collectively numbered NMV F58734 ) of Aglaophenia bakeri Bale, 1919 . Five of the slides are fertile specimens labelled “Western Port 1900” in Bale’s handwriting. Two of these are labelled with Bale’s catalogue numbers 301 and 302 as co-types. Another slide (NMV F58735 ), possibly part of the same colony is labelled co-type in Trebilcock’s handwriting. All are designated syntypes by Stranks (1993). I select microslide 301 as lectotype of Aglaophenia bakeri . Since there are no microscopic characters that distinguish Aglaophenia bakeri from Aglaophenia sinuosa I synonymise A. bakeri in A. sinuosa .

Distribution. South-eastern Australia and Tasman Sea; a first record from the Great Australian Bight.