Stenopsella fenestrata

• Main Author: Martino, Emanuela Di
• Format: Other/Unknown Material
• Language: unknown
• Published: 2022
• Subjects: Biodiversity; Taxonomy; Animalia; Bryozoa; Gymnolaemata; Cheilostomatida; Gigantoporidae; Stenopsella; Stenopsella fenestrata; North Atlantic
• Online Access: https://zenodo.org/record/6424516; https://doi.org/10.5281/zenodo.6424516

Stenopsella fenestrata (Smitt, 1873) (Fig. 9; Table 7) Hippothoa fenestrata Smitt, 1873: 47, pl. 6, fig. 142. Stenopsella fenestrata: Bassler 1952: 385. Material examined. Holotype by monotypy SMNH-Type-1800, North Atlantic Ocean, S of Tortugas, United States, depth 31 m. Leg. Gulf Stream Explorations 1868–69. Description. Colony encrusting, multiserial, unilaminar (Fig. 9A). Autozooids distinct with deep interzooidal furrows, salient, quincuncially or irregularly arranged, hexagonal or rhomboidal, longer than wide (mean L/ W 1.44) Frontal shield convex, finely granular and crenulated in young zooids at colony growing edge (Fig. 9D) but developing spinose frontal processes in older generations of autozooids (Fig. 9C), evenly and densely perforated, up to four-fifth of its length corresponding to the attachment line of the peristome; pseudopores circular, minute, 8–10 µm in diameter; marginal areolae undistinguishable. Primary orifice subcircular with pointed triangular condyles separating a quadrangular anter from a shallow, bowl-shaped sinus (Fig. 9D), usually hidden by a tubular, imperforate peristome, directed upwards and frontally, forming a transversely elliptical secondary orifice, about 200 µm long by 300 µm wide (Fig. 9C, D); spiramen placed at the base of the peristome at the end of a short tube with a more or less flared rim, transversely elliptical or reniform, 170–215 x 75–95 µm, facing frontally or downwards (Fig. 9B, C). Avicularia single or paired, placed at the base of the peristome, drop-shaped with rounded, slightly raised rostrum directed distolaterally and inwards, and complete crossbar (Fig. 9D, E). Ovicells and ancestrula not observed. Remarks. Smitt (1873) placed this species in Hippothoa Lamouroux, 1821 acknowledging that the small encrusting colony (in agreement with the syntype illustrated here) available from Pourtales’ collection lacked the most essential character of the genus, i.e. the orificial sinus. However, the observation of such a sinus on an erect fragment of what he thought ...