Plumularia flabellum Allman 1883

• Main Authors: Agís, José Ansín, Ramil, Fran, Calder, Dale R.
• Format: Other/Unknown Material
• Language: unknown
• Published: 2016
• Subjects: Biodiversity; Taxonomy; Animalia; Cnidaria; Hydrozoa; Leptothecata; Plumulariidae; Plumularia; Plumularia flabellum; Marion Island
• Online Access: https://zenodo.org/record/5684345; https://doi.org/10.5281/zenodo.5684345

Plumularia flabellum Allman, 1883 (Fig. 12; Table 6) Plumularia flabellum Allman, 1883: 19, pl. I, figs 1‒4; Stechow, 1 923: 225. Plumularia insignis flabellum: Billard, 1908: 759. Plumularia insignis var. flabellum: Billard, 1910: 34, fig. 15; Van Praët, 1979: 925. Material examined. Plumularia flabellum : fragments of type material at the Museum national d’Histoire naturelle, Paris, Challenger Expedition, Marion Island (South Africa), 91–137 m, 26-12-1883, MNHN-IK-2012- 16034, two slides: L. 1251. Two hydrocladia. L. 1282. Fragment 15 mm long, polysiphonic over basal half; nematothecae on secondary tubes. Distribution. Plumularia flabellum is known only from its type locality of Marion Island (South Africa), at depths between 91 and 137 m. Description. Fragment polysiphonic along basal part. Main tube segmented, with internodes separated by transverse nodes; each axial internode with two apophyses bearing hydrocladia, one in mid-region and another just under distal node, and two nematothecae, one just above basal node and another above first apophysis. Apophyses alternately directed right and left, arising only from main tube; each apophysis with one well-developed mamelon on upper surface, and with 3–4 nematothecae: two axillary and one or two distal to mamelon; one perisarcal ring occurring near node. Hydrocladia with proximalmost internode ahydrothecate, bearing one nematotheca on a small elevation towards base; perisarcal rings sometimes visible, with one basal and other distal; rest of hydrocladium comprising a succession of hydrothecate and ahydrothecate internodes. Hydrothecate internodes with one hydrotheca and three nematothecae: one mesial inferior and two laterals. Hydrotheca cup-shaped; adcauline wall fully adnate; abcauline wall straight; hydrothecal margin smooth, circular, perpendicular to hydrocladial axis. Mesial inferior nematotheca on a small elevation, reaching and sometimes surpassing hydrothecal base. Lateral nematothecae on a small apophysis placed below hydrothecal margin, extending ...