Stenostomum hemisphericum Nassonov, 1924

Reyes, Jhoe, Binow, Daniela, Vianna, Rogério T., Brusa, Francisco & Martins, Samantha E., 2021, Fig. 12. Majella pristis n in Periclimenaeus djiboutensis Bruce 1970, Zoological Studies 60 (22), pp. 1-33 : 7

Stenostomum hemisphericum Nassonov, 1924

( Fig. 2I )

Studied material: Three live whole-mounted individuals studied. Hand-drawings were made.

Localities: Site 3 (24/04/2019), associated with benthal microhabitat.

Description: Single live specimens are whitish, elongated. The anterior region of the body is somewhat pointed; while, the posterior, rounded. Brain lobes at the anterior region of the body, laterally paired ( Fig. 2I ). Two light-refracting bodies associated to each side of the posterior brain lobes. Mouth surrounded by pharynx glands. The pharynx is long, with lateral and oblique muscular fibers and glands associated along its extension. Excretophores along the intestine with no particular order ( Fig. 2I ).

Taxonomic remarks: The most remarkable feature of this species is the long pharynx which bears oblique and lateral muscle fibers associated with the pharynx. Despite few sampled individuals, morphology observed corresponds well to the descriptions made by Nassonov (1924), Marcus (1945a), Damborenea et al. (2011) and Braccini et al. (2017). This species is recorded for the third time in Brazil.

Distribution: Ukraine ( Nassonov 1924), Suriname ( Van der Land 1970), Brazil ( Marcus 1945b; Braccini et al. 2017) and Peru ( Damborenea et al. 2011).

Figures

Fig. 2. Live specimens of Catenulida. (A) Catenula lemnae, chain two zooids. (B–D) Myostenostomum vanderlandi: (B) habitus of whole-mounted individual, (C) detail of the anterior brain lobe and (D) detail of the posterior brain lobe. (E–F) Stenostomum glandulosum: (E) live individual, (F) free-hand schematic representation. (G) Stenostomum grande, a single zooid. (H) Stenostomum paraguayense, intestine with some food items. (I) Stenostomum hemisphericum, free-hand schematic representation.