Sycettusa hastifera ( Row, 1909 )

Sycettusa hastifera ( Row, 1909) View in CoL

( Fig. 39 View FIGURE 39 )

Synonyms: Grantilla hastifera — Row 1909: 200. Grantilla quadriradiata — Row 1909: 198. Grantessa hastifera — Dendy 1913: 19; Dendy & Row 1913: 752; Dendy 1916: 81; Borojević 1967: 210; Muricy et al. 1991: 1187; Muricy & Silva 1999: 160. Sycettusa cf. hastifera — Azevedo & Klautau 2007: 16. Sycettusa aff. hastifera — Voigt et al. 2012: 3. Sycettusa hastifera — Muricy et al. 2011: 29; Van Soest & De Voogd 2018: 113; Lopes et al. 2025: 191.

Type locality: Suez Harbour, Egypt, Red Sea .

Material examined: UFRJPOR9146, Saco do Poço , São Sebastião Island, Ilhabela, São Paulo State, Brazil, depth 13 m, coll. F. F. Cavalcanti, V. Padula & L. Kremer, 03/XII/2008 .

Colour: White in life and in ethanol ( Fig. 39A View FIGURE 39 ).

Morphology and anatomy: Small tubular specimen, with a single apical osculum, without conspicuous ornamentation ( Fig. 39A View FIGURE 39 ). The external surface is slightly hispid due to projecting diactines, particularly near the osculum, while the atrial surface is smooth ( Fig. 39A View FIGURE 39 ). Aquiferous system syconoid ( Fig. 39B View FIGURE 39 ).

The cortical skeleton consists of lanceolate diactines protruding through the surface ( Fig. 39C View FIGURE 39 ) and a tangential layer of slightly sagittal triactines ( Fig. 39D View FIGURE 39 ). The choanosomal skeleton is inarticulate ( Fig. 39B View FIGURE 39 ), composed of the longer paired actine of the subcortical pseudosagittal triactines ( Fig. 39E View FIGURE 39 ) and the unpaired actine of the subatrial sagittal triactines ( Fig. 39F View FIGURE 39 ). The atrial skeleton is formed exclusively by slightly sagittal triactines smaller than the cortical ones ( Fig. 39G View FIGURE 39 ).

Ecology: Specimen found exposed to sunlight, associated with algae.

Geographic distribution: Northern and Central Red Sea ecoregion— Egypt ( Row 1909), Saudi Arabia ( Van Soest & De Voogd 2018) and Gulf of Aqaba, Israel ( Van Soest & De Voogd 2018). Seychelles ecoregion— Providence Island (Dendy 1913), Bird Island and St. François Atoll ( Van Soest & De Voogd 2018), Seychelles. Western India ecoregion—Western India ( Dendy 1916). Natal ecoregion— South Africa ( Borojević 1967). Eastern Brazil ecoregion (invasive species)— Espírito Santo State ( Lopes et al. 2025), Brazil. Southeastern Brazil ecoregion (invasive species)—Arraial do Cabo and Angra dos Reis, Rio de Janeiro State ( Muricy et al. 1991; Azevedo & Klautau 2007); São Sebastião Island (Ilhabela), São Paulo State (present study), Brazil.

Remarks: Originally described from the Red Sea and subsequently reported from Indo-Pacific localities, this species was first recorded in the Southwestern Atlantic—where it is considered invasive—in Arraial do Cabo, Rio de Janeiro State ( Muricy et al. 1991). Since then, it has been reported from Angra dos Reis ( Azevedo & Klautau 2007) and the neighbouring state of Espírito Santo ( Lopes et al. 2025). In the present study, it is reported for the first time from São Paulo State, representing its southernmost known occurrence in the Western Atlantic.