Phalacrostemma Marenzeller 1895
Creators: name: Chávez-López, Yessica
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Sabellida
Sabellariidae
Phalacrostemma

description: Genus Phalacrostemma Marenzeller, 1895
Type species
Phalacrostemma cidariophilum Marenzeller, 1895, by monotypy.
Diagnosis
Operculum completely divided into two free lobes. Two rows of opercular paleae. Outer paleae arranged in spiral, with straight, cylindrical blades and ornamented thecae. Few (2–8) inner paleae arranged in one short row near to dorsal junction of inner marginal lobes, with straight, cylindrical, or slightly flattened blades. Two to six pairs of nuchal hooks with limbation. Few tentacular filaments arranged in a single row (simple), absent in some species. Median organ small, conical. Four parathoracic segments (Kirtley 1994; Capa & Hutchings 2019).
Key to species of Phalacrostemma Marenzeller, 1895 from the Western Atlantic *
1. Outer paleae with distal thecae partially surrounding the blade (Figs 11D, 12A, E) ......................... ................................................................... P. dorothyae Kirtley, 1994. Florida Keys, 349.3 m depth
– Outer paleae with distal thecae completely surrounding the blade (Fig. 7E) ................................... 2
2. Outer palea with mid-distal thecae with pectinate margins, extensions of similar size that form a horizontal stroke, like fringe (Fig. 8D, I) .......................................................................................... 3
– Outer palea with mid-distal thecae with lacerate margins, elongated extensions of different sizes that form an asymmetrical and irregular stroke (Fig. 15G) ..................................................................... 6
3. Outer palea with middle thecae with short extension, irregularly distributed, of different sizes and shapes (Fig. 8L) .............................................. P. gwendolynae Kirtley, 1994. Aruba, 228.7 m depth
– Outer palea with middle thecae with long extensions, of similar size and shape (Fig. 8C–D, I) ..... 4
4. Middle thecae of outer palea with inclined extensions, 10–16 times as long as wide (Fig. 8D) ........ ................................................ P. paulinae Kirtley, 1994. Delaware Bay, New Jersey, 2160 m depth
– Middle thecae of outer palea with straight extensions, 6–9 times as long as wide (Fig. 8I) ............ 5
5. Inner paleae with horizontal conspicuous thecae, margin of blade serrate (Fig. 6G); all opercular papillae of similar size (Fig. 5C, F) ......................... P. danieli sp. nov. Grenada Island, 597 m depth
– Inner paleae with horizontal thecae inconspicuous, margin of blade smooth (Fig. 17E–F); first pair of opercular papillae twice as large as the others (Fig. 16B) .............................................................. ............................................................................. Phalacrostemma sp. The Bahamas, 3000 m depth
6. Middle thecae of outer paleae almost longer than wide, margin forms a horizontal stroke with distal short extensions like denticles (Fig. 8M–N) ....................................................................................... ................. P. gloriaae Kirtley, 1994. Sanibel Island, Florida, Gulf of Mexico, 228.3–235.9 m depth
– Middle thecae of outer paleae three times as wide as long, margin forms a ‘V’ stroke (Fig. 15F) .... ........................................... P. perkinsi Kirtley, 1994. Andros Island, Bahamas, 1362–1364 m depth
description: Published as part of Chávez-López, Yessica, 2022, New species of sabellariids (Annelida: Sabellariidae) from the Caribbean Sea and the Gulf of Mexico, pp. 109-148 in European Journal of Taxonomy 831 on pages 118-119, DOI: 10.5852/ejt.2022.831.1873, http://zenodo.org/record/6885276