Antennella secundaria ( Gmelin, 1791 )

Peña Cantero, Álvaro L. & Horton, Tammy, 2017, Benthic hydroids (Cnidaria, Hydrozoa) from bathyal and abyssal depths of the Northeast Atlantic held in the modern Discovery Collections, Zootaxa 4347 (1), pp. 1-30 : 20-23

Antennella secundaria ( Gmelin, 1791)

( Fig. 9A–E )

Antennella secundaria — Ansín Agís et al., 2001: 140 –145, fig. 63 (synonymy).

Material examined. 13881#1, five stems up to 10 mm high, on Sertularella gayi , no gonothecae.

Description. Stems unbranched, up to 10 mm high, and with up to six hydrothecae. Stem resting on short apophysis. First two cauline internodes with two nematothecae, third internode longer and provided with six nematothecae ( Fig. 9A ). Remaining stem divided by alternating oblique and transverse nodes into an alternate series of hydrothecate/ahydrothecate internodes ( Fig. 9B–D ). Ahydrothecate internodes typically with three medial nematothecae ( Fig. 9C ), although internodes with only one also present ( Fig. 9B ). Hydrothecate internodes with one hydrotheca and four nematothecae: two flanking hydrothecal aperture on long pedicels ( Fig. 9E ) (frequently one without pedicel), one nematotheca at axil between adcauline hydrothecal wall and internode ( Fig. 9D ) and a mesial infrathecal nematotheca not reaching hydrothecal basal part ( Fig. 9B–D ). All nematothecae bi-chambered. Hydrotheca cup-shaped ( Fig. 9E ). Hydrothecal wall roughly straight in lateral view, but distinctly widening at distal part of adcauline side. Hydrothecal aperture circular; rim laterally concave ( Fig. 9E ).

Remarks. See Calder (1997b), Schuchert (1997) or Ansín Agís et al. (2001) for a wide discussion on the species.

Ecology and distribution. This is a eurybathic species, known between 0 ( Millard 1975) and 2700 m (Vervoort 2006); present material collected from the Porcupine Seabight at a depth of 863 m. Worldwide distribution in temperate, subtropical and tropical seas (Vervoort 2006).

Figures

FIGURE 9. Antennella secundaria (Gmelin, 1791): A, third stem internode with nematothecae; B, ahydrothecate internode with one nematotheca; C, ahydrothecate internode with three nematothecae; D, lateral view of hydrothecate internode showing hydrotheca and mesial superior nematotheca (arrow); E, lateral view of hydrothecate internode showing hydrotheca and lateral nematothecae (arrow). Nemertesia ramosa (Lamarck, 1816): cauline apophysis showing nematothecae and mamelon (arrow); G, fragment of hydrocladium showing arrangement; H, hydrocladial internode with hydrotheca and nematothecae. Scale bars: 200 µm (A – C, F – G), 100 µm (D – E, H).