Amphoriscus pedunculatus Klautau, Cavalcanti & Borojević, 2017

Pereira, Sara Emilly, Azevedo, Fernanda, Hajdu, Eduardo, Cavalcanti, Fernanda F. & Klautau, Michelle, 2025, Calcareous sponges (Porifera, Calcarea) from São Sebastião, São Paulo: new species and new records in two marine protected areas of Southeastern Brazil Ecoregion, Zootaxa 5688 (1), pp. 1-107 : 16-17

Amphoriscus pedunculatus Klautau, Cavalcanti & Borojević, 2017

( Fig. 6 ; Table 5)

Synonyms: Amphoriscus pedunculatus — Klautau et al. 2017: 105; Cóndor-Luján et al. 2019: 1825; Chagas & Cavalcanti 2021: 51.

Type locality: Saco do Poço , São Sebastião Island, Ilhabela, São Paulo State, Brazil .

Material examined: MNRJ2043 , Saco do Poço, São Sebastião Island, Ilhabela, São Paulo State, Brazil, depth 13 m, coll. E. Hajdu & L. H. Lima, 03/II/1999 . MNRJ30125 , Alcatrazes Archipelago , São Sebastião, São Paulo State, Brazil, depth 12 m, coll. M. Custódio & C. Santos, 03/ V /2002. UFRJPOR6933, Sumítica Island , Ilhabela, São Paulo State, Brazil, depth 9 m, coll. F. F. Cavalcanti & V. Padula, 02/XII/2008. UFRJPOR6998, close to Dart shipwreck, São Sebastião Island , Ilhabela, São Sebastião, São Paulo State, Brazil, depth 4 m, coll. F. F. Cavalcanti, 30/XI/2008. UFRJPOR7025, Saco do Poço , São Sebastião Island , Ilhabela , São Paulo, Brazil, depth 7 m, coll. F. F. Cavalcanti, 03/XII/2008. UFRJPOR7027, Saco do Poço , São Sebastião Island, Ilhabela, São Paulo, Brazil, depth 13 m, coll. F. F. Cavalcanti , V. Padula & L. Kremer, 03/XII/2008. UFRJPOR7042, Costa do Aquário , Búzios Island, Ilhabela, São Paulo State, Brazil, depth 12 m, coll. F. F. Cavalcanti , V. Padula & R. Berlinck, 05/XII/2008 .

Colour: Beige in life and white with a yellowish peduncule in ethanol ( Fig. 6A, B ).

Morphology and anatomy: Specimens with a tubular body, yellowish solid peduncle at the base, and apical osculum ornamented with few trichoxeas not forming a conspicuous crown ( Fig. 6A, B ). The external surface is slightly hispid only under high magnification due to numerous trichoxeas ( Fig. 6A, B ). The atrial cavity is also hispid but due to the apical actines of the atrial tetractines. Aquiferous system syconoid.

The oscular skeleton is formed by tetractines and a few trichoxeas. The cortical skeleton is composed of tetractines and triactines, the latter less abundant ( Fig. 6C ). The cortical spicules are arranged pointing the unpaired actine to the base of the sponge. Short trichoxeas are abundant throughout the cortex ( Fig. 6C, D ). The subatrial skeleton is formed by few triactines ( Fig. 6E ). The choanoskeleton is inarticulate. The atrial skeleton is composed only of tetractines, which project their apical actines into the atrial cavity ( Fig. 6D, E ). The peduncle has externally abundant triactines and few tetractines, which are identical to the cortical ones, in addition to trichoxeas. As in the cortex of the main body, the triactines and tetractines have a parallel organisation along the surface of the peduncle.

Spicules ( Table 5):

Trichoxeas: Short, very thin, straight or slightly curved and sharp. Size: 110.5 (±13.7)/1.3 (±0.0) µm.

Cortical triactines and tetractines: Sagittal, with conical and sharp actines. Basal actines are straight and the unpaired actine is longer than the paired ones. The apical actine of the tetractines is straight, conical, sharp and, on average, shorter than the unpaired actine ( Fig. 6F, G ). Triactines size: paired—188.0 (±36.7)/22.4 (±3.9) µm; unpaired—257.0 (±45.6)/23.1 (±4.2) µm. Tetractines size: paired—217.5 (±36.6)/30.8 (±4.1) µm; unpaired—314.0 (±49.0)/31.9 (±3.4) µm; apical—285.8 (±32.5)/29.0 (±4.8) µm.

Subatrial triactines: Sagittal, with slightly conical and sharp actines. The paired actines are slightly curved towards the unpaired one, which is straight and longer ( Fig. 6H ). Size: paired—89.0 (±18.0)/9.0 (±1.5) µm; unpaired—166.3 (±23.6)/9.5 (±1.7) µm.

Atrial tetractines: Sagittal, with slightly conical and sharply pointed basal actines.The paired actines are slightly curved, while the unpaired one is straight and longer ( Fig. 6I ). The apical actine is a little curved, smooth, conical, sharp, and shorter than the basal ones. Size: paired—81.5 (±10.1)/8.1 (±1.1) µm; unpaired—123.5 (±15.9)/8.2 (±0.9) µm; apical—76.5 (±8.7)/7.6 (±1.2) µm.

Ecology: The specimens MNRJ2043 and MNRJ30125 were associated with bivalve molluscs and bryozoans. Some specimens were found protected from sunlight on a bank of calcareous algae.

Geographic distribution: Southeastern Brazil ecoregion—São Sebastião, Búzios and Sumítica Islands (Ilhabela) and Alcatrazes Archipelago (São Sebastião), São Paulo State ( Klautau et al. 2017; present study); Arraial do Cabo, Rio de Janeiro State ( Klautau et al. 2017), Brazil.

Remarks: Amphoriscus pedunculatus is a quite common species in the study area, its type locality, and was recently re-described by Chagas & Cavalcanti (2021). This species was also reported for Rio de Janeiro State ( Klautau et al. 2017), so its distribution is, at least for now, restricted to the Southeastern Brazil ecoregion. It is important to highlight a variability in spicule dimensions between the specimen MNRJ2043 and the holotype. The actines of the cortical triactines and tetractines, as well as the basal actines of the atrial tetractines are thicker [basal actines of atrial tetractines—paired actines: 8.1 (±1.1) µm, unpaired actine: 8.2 (±0.9) µm] and the trichoxeas are longer [110.5 (±13.7) µm] in the specimen analysed here than in the holotype [basal actines of atrial tetractines— paired actines: 5.0 (±1.5) µm, unpaired actine: 5.0 (±1.5) µm; trichoxea: 40.9 (±15.8) µm]. Additionally, the apical actine of the cortical tetractines is longer than the basal actines in the holotype [paired actine: 179.5 (±32.3) µm, unpaired actine: 238.5 (±58.2) µm, apical actine: 288.8 (±53.9) µm], while in MNRJ2043 the unpaired actine of these spicules is, on average, longer than the other actines [paired actines: 217.5 (±36.6) µm, unpaired actine: 314.0 (±49.0) µm, apical actine: 285.8 (±32.5) µm].

Figures

FIGURE 6. Amphoriscus pedunculatus. A, B. Preserved specimens MNRJ2043 and MNRJ30125, respectively. C. Tangential section of the cortex. D. Cross section. E. Subatrial skeleton (arrowheads).F.Cortical triactine.G. Cortical tetractine. H. Subatrial triactine. I. Atrial tetractine. All pictures were taken from the specimen MNRJ2043. cx = cortex, at = atrium, p = paired actine, u = unpaired actine, ap = apical actine.