Magelona symmetrica Mortimer & Mackie 2006

• Main Authors: Magalhães, Wagner F., Bailey-Brock, Julie, Watling, Les
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2018
• Subjects: Biodiversity; Taxonomy; Animalia; Annelida; Polychaeta; Spionida; Magelonidae; Magelona; Magelona symmetrica; DML
• Online Access: https://doi.org/10.5281/zenodo.5967852; http://treatment.plazi.org/id/B1320B768E19FFB902F6FEB9FCDDAB45

Magelona cf. symmetrica Mortimer & Mackie, 2006 Figures 6 and 7 (A‒C) Material examined. Mariana Islands, Guam, Northern District outfall, 13°29'14" N, 144°44'54" E, Jan/2007, 40‒ 52 m, Sta. N1R1, (1 complete specimen, BPBM-R 3874); Sta. N3R1 (3 af, BPBM-R 3875); Agana outfall, 13°33'08" N, 144°48'25" E, Jan/2007, 65‒ 100 m, Sta. A2R2 (2 af, BPBM-R 3876). Diagnosis. Prostomium as long as wide, lacking prostomial horns. Notopodia and neuropodia of chaetigers 1‒8 with triangular postchaetal lamellae with smooth upper edges. Thoracic superior processes absent. Chaetiger nine with only simple bilimbate capillaries. Abdominal hooded hooks tridentate. Description. One complete specimen observed, all others posteriorly incomplete; prostomium 0.28‒0.35 mm long, 0.25‒0.36 mm wide; thorax 1.40‒2.20 mm long (including prostomium), 0.27‒0.49 mm wide; abdomen 0.20‒0.48 mm wide; total length 5.57‒7.39 mm for 24‒42 chaetigers. Prostomium as long as wide (L:W ratio 0.97‒1.12), flattened distally, anterior margin smooth or having discrete crenulations, lacking prostomial horns; (Figs 6A, C; 7A). Two pairs of longitudinal dorsal ridges; outer pair not distinct and adjacent to inner pair; the latter pair with a wide medial gap, diverging slightly distally (Fig. 6A, C). Burrowing organ not observed. Single palp observed, arising ventro-laterally from base of prostomium and extending to chaetiger 18 (Fig. 6A); measured 2.51 mm long; non‒papillated region very short, extending to chaetiger 1 (Fig. 6A). Papillae short proximally but long for majority of length, elongate; proximally and medially with six rows of papillae and distally reducing to four rows. Achaetous segment as long as chaetiger 1 (Fig. 6A). Thoracic segments wider than long; chaetigers 1‒8 similar; parapodia biramous; notopodia and neuropodia similar, with low prechaetal lamellae and triangular postchaetal lamellae of similar size throughout thorax (Fig. 6B); notopodial lamellae distally smooth. Prechaetal superior processes (DML) and ventral digitiform lobes (VNL) ...