Marionina aestuum Stephenson 1932

• Main Authors: Klinth, Mårten J., Rota, Emilia, Martinsson, Svante, Prantoni, Alessandro L., Erséus, Christer
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2021
• Subjects: Biodiversity; Taxonomy; Animalia; Annelida; Clitellata; Enchytraeida; Enchytraeidae; Marionina; Marionina aestuum; South Georgia Island
• Online Access: https://doi.org/10.5281/zenodo.6461129; http://treatment.plazi.org/id/039DC377FFA3FFC14DC8F9C8FEA159A1

MARIONINA AESTUUM STEPHENSON, 1932 (FIGS 9B, C, 10, 11) Marionina aestuum Stephenson, 1932: 246–251. Lumbricillus aestuum – Nielsen & Christensen, 1959: 96. Type material: BMNH 1931:6:23:42–43 (in alcohol, not studied), BMNH 1933.2.23.893–896, four mature sectioned specimens (studied). Syntypes. Loc. Shore of Bay of Isles, South Georgia. Leg. ‘Discovery’ 1925–1927 (Stephenson, 1932) (Boros & Sherlock, 2010). Type locality: Shore of Bay of Isles, South Georgia Island. New material examined: SMNH 198154 (CE 12477) one mature specimen collected in 2010 from South Georgia. For information on collection localities and GenBank accession numbers for COI barcodes, see Table 1 and the Supporting Information (Table S1). Description of new, mounted, material with comparative notes to Stephenson’s sectioned material: Dark grey worm (at least when preserved), with subepithelial black pigmentation, densest dorsally, decreasing in intensity ventrally. Length of first 20 segments 2.1 mm (fixed, amputated specimen); first 15 segments 1.9 mm long; width at clitellum 0.65 mm. Chaetae sigmoid (Fig. 10A). Upper bundles dorsolateral (closer to lateral line than the ventral bundles), with five to eight (possibly more) chaetae anterior to clitellum; numbers not discernable in postclitellar segments. Ventral bundles with 11–15 chaetae anterior to clitellum, nine to 11 chaetae posteriorly, at least to XX. The longest measured chaetae 95 µm long, ~5 µm wide. Epidermis densely covered with rows of pale gland cells; sectioned material also showed dense, deeply staining granular gland cells. Clitellum with reticulate pattern of gland cells, extending over XII–XIII, absent ventrally. Head pore not observed. Coelomocytes numerous, ~15 µm long; round, oval or spindle shaped; granulated, with distinct nucleus. Paired pharyngeal glands (Fig. 10B) present in IV, V and VI, with third pair extending back into VII; each pair dorsally separate. Origin of dorsal vessel not discernable, with peristomial bifurcation. Nephridia ~95 µm long (longer ...