Hydractinia parvispina Hartlaub 1905

• Main Authors: Galea, Horia R., Schories, Dirk
• Format: Text
• Language: unknown
• Published: Zenodo 2012
• Subjects: Biodiversity; Taxonomy; Animalia; Cnidaria; Hydrozoa; Anthoathecata; Hydractiniidae; Hydractinia; Hydractinia parvispina; Antarctic; New Zealand; Graham Land; Dyer; Bakker; Edwards Islands; Tuatara; Antarc*; Antarktis*; Marion Island; Prince Edward Islands
• Online Access: https://dx.doi.org/10.5281/zenodo.6174581; https://zenodo.org/record/6174581

Hydractinia parvispina Hartlaub, 1905 (fig. 2 A–C) Hydractinia parvispina Hartlaub, 1905: 518, fig. A. — Jäderholm, 1905: 5, pl. 3 figs 4, 5. — Jäderholm, 1917: 4. —? Millard, 1971: 402, fig. 4. — Stepanjants, 1979: 14, pl. 1 fig. 8. — Branch & Williams, 1993: 7, fig. — Schuchert, 1996: 44, fig. 23. not Hydractinia parvispina — Ralph, 1953: 63, fig. 1. Material examined. Stn. FSI — 01.iii. 2010, PTA033 (4 m): a female colony on gastropod shell (MHNG-INVE- 79601). Description . Hydrorhiza crust-like, covered with naked coenosarc; spines chitinous, simple, rather conspicuous. Polyps dimorphic, with gastro- and gonozooids; the former elongate, tubular, with up to 13 filiform tentacles; gonozooids slightly smaller, with up to 12 tentacles; tentacles in one whorl, possibly amphicoronate in life; hypostome dome-shaped. Available colony female; one to eight gonophores per gonozooid, in one whorl, a short distance below tentacles; each gonophore with up to 8 nearly spherical eggs. A few gonozooids devoid of hypostome and tentacles (possibly reproductive exhaustion). Nematocysts (seen undischarged: desmonemes (5.7– 6.1)×(3.1–3.4) µm; and two size classes of microbasic euryteles, (7.7 –9.0)×(2.7 –3.0) µm and (10.1–11.4)×(3.4– 4.1) µm, respectively. Remarks . Due to the varied degree of contraction in our fixed material, the real size of the polyps could not be determined. The number of tentacles was ascertained in a restricted number of less contracted individuals, and should not be taken as absolute. Hartlaub (1905) mentioned 15 and 11 tentacles in the gastro- and gonozooids, respectively. Millard's (1971) material from Marion Island agrees partly with the present specimen: there are differences in the number of tentacles (11–16 and 4–6 in gastro- and gonozooids, respectively), the cnidome composition (two types of capsules instead of three), as well as the selection of a different substrate for the colony ("on stones under rocks in the lower littoral region"). Distribution in Chile . Picton Island (Hartlaub 1905), Strait of Magellan (present study). World records . Falkland Islands (Hartlaub 1905), Graham Land (Jäderholm 1905), South Georgia (Jäderholm 1905, 1917),? Marion Island (Millard 1971). The New Zealand record by Ralph (1953) is doubtful, as explained by Schuchert (1996). : Published as part of Galea, Horia R. & Schories, Dirk, 2012, Some hydrozoans (Cnidaria) from Central Chile and the Strait of Magellan, pp. 19-67 in Zootaxa 3296 on pages 25-26, DOI: 10.5281/zenodo.280882 : {"references": ["Hartlaub, C. (1905) Die Hydroiden der Magalhaensischen Region und chilenischen Kuste. In: Fauna chilensis. Zoologische Jahrbucher, Suppl. 6 (3), 497 - 714.", "Jaderholm, E. (1905) Hydroiden aus antarktischen und subantarktischen Meeren gesammelt von der schwedischen Sudpolar- Expedition. Wissenschaftliche Ergebnisse der Schwedischen Sudpolar-Expedition 1901 - 1903, 5 (8), 1 - 41.", "Jaderholm, E. (1917) Hydroids from the South Seas. Redogorelse for Norrkopings Hogre Allmanna Laroverk Lasaret, 1916 - 1917, 1 - 25.", "Millard, N. A. H. (1971) Hydrozoa. In: van Zinderen Bakker, E. M., Winterbottom J. M. & R. A. Dyer, R. A. (Eds.), Marion and Prince Edwards Islands. A. A. Balkema, Cape Town, pp. 396 - 408.", "Stepanjants, S. D. (1979) Gidroidy vod antarktiki i subantarktiki. In: Rezul'taty biologicheskikh issledovanii sovetskikh antarkticheskikh ekspeditsii, 6. Issledovaniya Fauny Morei, 22 (30), 1 - 99.", "Branch, M. L. & Williams, G. C. (1993) The Hydrozoa, Octocorallia and Scleractinia of subantarctic Marion and Prince Edward Islands: illustrated keys to the species and results of the 1982 - 1989 University of Cape Town surveys. South African Journal of Antarctic Research, 23 (1 - 2), 3 - 24.", "Schuchert, P. (1996) The marine fauna of New Zealand: athecate hydroids and their medusae (Cnidaria: Hydrozoa). New Zealand Oceanographic Institute Memoir, 106, 1 - 159.", "Ralph, P. M. (1953) A guide to the athecate (gymnoblastic) hydroids and medusae of New Zealand. Tuatara, 5 (2), 59 - 75."]}