Lytocarpia parvispiralis, Watson, 2019

Watson, Jeanette E., 2019, Bathyal and abyssal hydroids (Hydrozoa, Leptothecata) from southeastern Australia, Memoirs of Museum Victoria 78, pp. 65-72 : 69

Lytocarpia parvispiralis sp. nov.

http://zoobank.org/urn:lsid:zoobank.org:act:DD8BF2A6-A3A6-

4156-AB1E-1F03B1D2C408

Figure 2 e, f

Record. QM G337453 . Holotype, one microslide. Coll: Coral Sea , Queensland, 23.7503 S, 154.5718 E to 23.7739 S, 154.5464 E 2093– 2156 m, Brenke epibenthic sled, 14/06/2017. QM G337985 . Paratype, one microslide from holotype colony .

Description. Infertile colony 90 mm long, broken in two. Hydrorhiza comprising a group of smooth tubular stolons coalescing to form parallel polysiphonic tubes of lower stem. Colony with three primary branches on upper stem section. Branches monosiphonic, cylindrical, with a row of up to 15 nematothecae below first hydrocladium.

Hydrocladia with many hydrothecae. Hydrocladium long, lax, apophysis large, distal node oblique, two nematothecae in a line below hydrocladium and one beside axil. Hydrocladial internode narrow, node distinct, slightly oblique, two partial septa passing into internode from base of hydrotheca, one below hydranth, the other about halfway along internode.

Hydrotheca occupying much of internode, slipper-shaped, abcauline and adcauline hydrothecal walls gently convex, adcauline wall fully adnate to internode. Margin slightly oblique to internode axis, anterior cusp tongue-shaped, followed by two moderately pointed cusps then three indefinite low cusps, interspaces between very shallow.

Median nematotheca digitate, very short, almost entirely adnate to hydrotheca, terminal orifice small, pointing upwards, open down to hydrotheca. Lateral nematotheca tubular, just reaching margin of hydrotheca, orifice sinusoidal down to internode. Cauline nematothecae the same as laterals. Hydranth with approximately 10 tentacles, hypostome mound-shaped.

Perisarc moderately thick throughout colony.

Remarks. Unfortunately the preserved colony was not examined in detail prior to mounting. Its position on the microslide now prevents determination of whether the hydrocladia were spirally arranged. Its close resemblance to Lytocarpia spiralis ( Totton, 1930) suggests that the hydrocladia may be spirally arranged. The hydrothecae are much smaller and the marginal cusps less prominent than in L. spiralis (see Vervoort and Watson 2003). Lytocarpia parvispiralis is clearly an abyssal congener of L. spiralis , a species common around New Zealand to depths of 1126 m.

Etymology. The name alludes to the smaller size of L. parvispiralis compared to its close congener L. spiralis .

Figures

Figure 2. a–f. a, b, Zygophylax concinna. a, branch internodes with hydrothecae. b, hydrotheca. c, d, Amphisbetia ramifera sp. nov. c, stem with subopposite hydrothecae and axillar hydrotheca. d, branch with opposite hydrothecae. e, f. Lytocarpia parvispiralis sp. nov. e, holotype colony. f, hydrothecae, lateral view.