Phalacrostemma undetermined

• Published in: Journal of Geophysical Research
• Main Author: Chávez-López, Yessica
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2022
• Subjects: Biodiversity; Taxonomy; Animalia; Annelida; Polychaeta; Sabellida; Sabellariidae; Phalacrostemma; Phalacrostemma undetermined; North Atlantic
• Online Access: https://doi.org/10.5281/zenodo.6885918; http://treatment.plazi.org/id/03B2EE18FFE3FFB826F57236EAA1008C

Phalacrostemma sp. Figs 16–17 Material examined NORTH ATLANTIC – Southeastern Bahamas • 1 incomplete spec.; RV Columbus Iselin , stn 47; 23°43′ N, 77°09′ W; depth 3000 m; 24 Feb. 1973; UMML-22.1194. Description BODY. Incomplete specimen (UMML-22.1194), 10 mm long, 2.5 mm wide, five abdominal segments (Fig. 16). OPERCULUM. Opercular disc truncate. Outer paleae arranged spirally, 37 paleae on each lobe. Inner paleae arranged diagonally, two paleae on right lobe, one palea on left. Outer paleae amber, cylindrical, 3 mm long (Fig. 17A). Proximal region with compact thecae, margins non-expanded (Fig. 17B). Thecae of middle region compact with non-expanded margins to thecae with margins irregular slightly expanded (Fig. 17C); tips hirsute (Fig. 17D). Inner paleae amber, cylindrical, with thecae inconspicuous; tip blunt, slightly inclined (Fig. 17E–F). Opercular stalk brown, 1.6 times as wide as long (Fig. 16). Opercular papillae in one row peripheral to outer paleae; 10–11 papillae on each lobe. Papillae conical, small, and tapered, 2–3 times as long as wide (Fig. 16E–F). First papilla twice as large as others, appears on dorsal region of opercular peduncle, at level of nuchal hooks (Fig. 16A– B). Four pairs of amber nuchal hooks, compressed, tip falcate, with short limbation. Limbation not reaching tip curvature, three times as long as tip (Fig. 17G). Palps robust, tapered, twice as long as wide (Fig. 16D). Pair of broad buccal flaps (Fig. 16C–D). Tentacular filaments absent. Median organ conical, brown, without eyespots. THORAX. First thoracic segment with 3–4 long, triangular-shaped lateral lobes (Fig. 16D–F), and capillary neurochaetae. Second segment with two triangular-shaped lateral lobes and paired branchiae, without chaetae (Fig. 16B, F). PARATHORAX. With four segments, all with paired branchiae (Fig. 16E). Notopodia with seven lanceolate chaetae and seven capillary chaetae (Fig. 17H). Neuropodia with capillary chaetae. ABDOMEN. Abdominal segments brownish. Neurochaetae capillary, ornamented with irregular ...