Marionina undetermined

• Main Authors: Klinth, Mårten J., Rota, Emilia, Martinsson, Svante, Prantoni, Alessandro L., Erséus, Christer
• Format: Other/Unknown Material
• Language: unknown
• Published: 2021
• Subjects: Biodiversity; Taxonomy; Animalia; Annelida; Clitellata; Enchytraeida; Enchytraeidae; Marionina; Marionina undetermined; Snow Island; South Shetland Islands; Antarc*; Antarctica
• Online Access: https://zenodo.org/record/6461137; https://doi.org/10.5281/zenodo.6461137

MARIONINA SP. ‘SNOW IS.’ (FIGS 9A, 14) Material examined: SMNH198155 (CE34647) and SMNH198156 (CE34648), two semi-mature specimens from Snow Island (South Shetland Islands), Antarctica. For information on collection localities and GenBank accession numbers for COI barcodes, see Table 1 and the Supporting Information (Table S1). Description: Live colour unknown; and specimens apparently without pigmentation. Length of first 16–19 segments 2.4–2.9 mm (fixed, amputated specimens); first 15 segments 2.2–2.3 mm long; width at XII 0.27 mm. Chaetae slightly sigmoid (Fig. 14A). Upper bundles dorsolateral (closer to lateral line than ventral bundles), with three to four chaetae anterior to clitellum, (three) four in postclitellar segments, at least to XIX. Ventral bundles with four chaetae throughout to XIX. The longest measured chaetae of each worm 55 µm long, ~3 µm wide. Epidermis densely covered with rows of pale gland cells. Clitellum not developed. Head pore at 0/I. Coelomocytes numerous, 10–15 µm long; round, oval or spindle shaped; granulated, with distinct nucleus. Paired pharyngeal glands (Fig. 14B) present in IV, V and VI; only third pair with ventral lobes and dorsally converging but connection not discernible. Origin of dorsal vessel indiscernible, but with peristomial bifurcation. Nephridia observed in 7/8–8/9, anteseptale with funnel only, postseptale elongated oval with terminal efferent duct. Brain with posterior incision, with clusters of perikarya on prostomial nerves and at ventral ends of circumoesophageal connectives (Fig. 9A). Ventral nerve cord with small subbuccal bulb (Fig. 9A); see Marionina discussion above. Male genitalia not fully developed. Developing male cells free floating in XI. Developing sperm funnels in XI, 60–65 µm long, 40 µm wide. Thin line of cells extending backwards from sperm funnels to what will become the male opening. Developing spermathecae in V, shape uncertain. No midventral subneural glands observed. Geographical distribution: Known only from Snow Island (South Shetland ...