Hydractinia angusta Hartlaub 1904

• Main Authors: Galea, Horia R., Schories, Dirk
• Format: Other/Unknown Material
• Language: unknown
• Published: 2012
• Subjects: Biodiversity; Taxonomy; Animalia; Cnidaria; Hydrozoa; Anthoathecata; Hydractiniidae; Hydractinia; Hydractinia angusta; Antarctic; Briggs; King George Island; Antarc*; Antarctica
• Online Access: https://zenodo.org/record/3506944; https://doi.org/10.5281/zenodo.3506944

Hydractinia angusta Hartlaub, 1904 (Pl. 1 A–E, Fig. 2 A–C) Hydractinia angusta Hartlaub, 1904: 7, pl. 4. — Naumov & Stepanjants, 1972: 35, fig. 1. — Stepanjants, 1979: 13, pl. 1 fig. 7. — Peña Cantero & Ramil, 2006: 950, fig. 2 A. — Peña Cantero, 2012: 855. Hydronema angustum — Stechow, 1923: 67. — Totton, 1930: 138. — Briggs, 1939: 10. Hydractinia dendritica Hickson & Gravely, 1907: 9, pl. 2 figs 7–10. Hydronema dendriticum — Stechow, 1921: 252. — Stechow, 1923: 67, fig. F. ? Hydractinia sp. —Stepanjants, 1972: 59, fig. 4. Material examined. Stn. SHO — 16.ii. 2011, Ant.09/ 2011 (43 m): fertile (female) colony on worm tube (MHNG- INVE- 79798). Stn. ARD — 28.i. 2011, Ant. 11 / 2011 (39 m): fertile (female) colony on worm tube (MHNG-INVE- 79799). Description. Hydrorhiza an encrusting mat issued through the coalescence of the stolonal system, covered by naked coenosarc (Pl. 1 C). Spines present, often continuous with each other (Pl. 1 D), provided with low ridges of perisarc (Pl. 1 E), open or closed at tips. Polyps dimorphic: gastro- and gonozooids. Gastrozooids up to 5 mm high in fixed material, notably longer in life (Pl. 1 A); with 12–14 amphicoronate tentacles and dome-shaped hypostome. Gonozooids dwarfed, less than 0.5 mm high, and degenerate, with 1–5 tentacles, and possibly no mouth; 4–6 rounded gonophores basally, each carrying three eggs. Nematocysts: desmonemes (6.0– 6.5) × (3.6–3.8) µm and microbasic euryteles (8.9–9.8) × (3.1–3.5) µm (both measured undischarged). Remarks. Totton (1930) reexamined the type of H. dendritica Hickson & Gravely, 1907 and suggested that it could reasonably be considered as conspecific with Hartlaub's (1904) species, an opinion which is followed here. Geographical distribution. Circum-Antarctic (Peña Cantero & Ramil 2006). Published as part of Galea, Horia R. & Schories, Dirk, 2012, Some hydrozoans (Cnidaria) from King George Island, Antarctica, pp. 1-21 in Zootaxa 3321 on page 2, DOI:10.5281/zenodo.213236