Tasmanaria edentula ( Bale, 1924 )

Galea, Horia R. & Schuchert, Peter, 2019, Some thecate hydroids (Cnidaria: Hydrozoa) from off New Caledonia collected during KANACONO and KANADEEP expeditions of the French Tropical Deep-Sea Benthos Program, European Journal of Taxonomy 562, pp. 1-70 : 11-13

Tasmanaria edentula ( Bale, 1924)

Fig. 4

Tasmanaria edentula – Vervoort & Watson 2003: 238 , fig. 57A– E.

Material examined

PACIFIC OCEAN • a 6.8 cm high, unbranched colony fragment, with only the perisarc left; off New Caledonia, stn DW4932; 25°05′ S, 160°00′ E; 287–290 m; 3 Sep. 2017; KANADEEP leg.; MNHN- IK-2015-472.

Remarks

The present material likely represents a branch fragment, since no (remains of) apophyses could be seen as in a portion of stem. It was likely fertile, but all gonothecae are now lost; their attachment points are clearly visible in its proximal part, while future foramina could be noted distally as rounded, flimsy perisarc patches below the hydrothecal bases. The hydrothecae are partly damaged (especially their margins) due to the collecting technique, and some are filled in with sand particles. Their morphology, combined to their dimensions (adnate wall = 1215–1290 µm long, diameter at aperture = 480–505 µm, maximum width = 515-540 µm) point, with little doubt, towards T. edentula , as described by Vervoort & Watson (2003).

Owing to the distinctive morphology of its hydrothecae, this species may prove to belong to the Staurothecidae , instead of the Sertulariidae . Vervoort &Watson (2003: 238) observed in some hydrothecae “remnants of hyaline opercular material, usually attached inside [the] hydrothecal rim”. Antsulevich & Vervoort (1993: 439) cite Bale (1924: 238), who described the operculum as “trivalvate”, hence their provisional assignment of this species to their new genus, Papilionella Antsulevich & Vervoort, 1993 .

On the other hand, “a low operculum of one saucer-shaped valve, much torn and usually collapsed inward” was noted in T. aegis Watson & Vervoort, 2001 , the type species of the genus ( Watson & Vervoort 2001: 172).

Its gonotheca shows morphological affinities with those of species of Staurotheca , e.g., S. amphorophora Naumov & Stepanjants, 1962 ( Stepanjants 1979) . In addition, the hydrothecal shape and the gonothecae provided with apical spines in T. pacifica Vervoort & Watson, 2003 (see original account), suggest possible affinities with the Staurothecidae , as well. New molecular evidence is expected to shed light on the systematic position of the genus.

Distribution

Off northern New Zealand ( Vervoort & Watson 2003) and off New Caledonia (present study).

Family Syntheciidae Marktanner-Turneretscher, 1890

Genus Billardia Totton, 1930

Figures

Fig. 4. Tasmanaria edentula (Bale, 1924). A–B. Portion of branch (A), hydrotheca (B), both from sample MNHN-IK-2015-472. Scale bars: A: 1 mm; B = 500 µm.