Amphoriscus pedunculatus Klautau & Cavalcanti & Borojevic 2017

AMPHoriscus PEdunculatus sp. nov.

(Figures 2 –4; Table 1)

Diagnosis. Amphoriscus with a peduncle, cortical skeleton composed of trichoxeas, triactines and tetractines and subatrial skeleton composed of triactines.

Material examined (Five specimens). Holotype: UFRJPOR 5802, Saco do Poço, São Sebastião, São Paulo, Brazil (longitude -45.2482, latitude -23.7612), 13 m depth, coll. F. F. Cavalcanti, V. Padula & L. Kremer, 0 3 December 2008. Paratype: UFRJPOR 5803, Saco da Ponta Grossa, São Sebastião, São Paulo, Brazil (longitude - 45.2319, latitude -23.7755), 6 m depth, coll. F. F. Cavalcanti & V. Padula, 0 3 December 2008. Additional material: UFRJPOR 5801, Ilha da Serraria, São Sebastião, São Paulo, Brazil (longitude -45.2289, latitude - 23.8133), 9 m depth, coll. F. F. Cavalcanti & V. Padula, 0 4 December 2008. MNRJ 5818, Alcatrazes Archipelago, São Sebastião, São Paulo, Brazil (longitude -45.6833, latitude -24.1000), 12 m depth, coll. M. Custódio & C. Santos, 0 3 May 2002. MNRJ 5776, Saco da Saia, Arraial do Cabo, Rio de Janeiro, Brazil (-42.0100 longitude, - 23.0064 latitude, Saco da Saia), coll. G. Muricy, 17 March 1988.

Etymology. From the Latin pedunculus (= peduncle), for the presence of a peduncle in this species.

Colour. White in life and in ethanol but the peduncle is brownish/orange (Figure 2A) due to the presence of debris and algae retained by a thick external layer of trichoxeas.

Morphology. Sponge tubular (1.3 / 0.2 cm) with two distinct parts: a body containing the choanosome (0.8 / 0.2 cm) and a solid peduncle (0.5 / 0.1 cm) (Figures 2A, B, 3A). The specimens were solitary or, occasionally, two tubes were connected at their bases (Figure 2B). The atrial cavity is central, with a brilliant and hispid surface. The osculum is single, apical, surrounded by a short crown of trichoxeas. The oscular fringe is sustained by a layer of tetractines arranged in parallel, forming a regular circle around the osculum (Figure 2C). The sponge is pierced by trichoxeas.

Anatomy. The aquiferous system is syconoid. Inhalant cavities are limited to spaces between the distal cones of choanocyte chambers. The cortical skeleton is composed of triactines tangentially arranged and large tetractines (Figures 2D, 3D). The long apical actines of the tetractines are centripetally oriented (Figure 2E). Thin trichoxeas are spread in the cortical skeleton, mainly at the distal cones where they form tufts. The choanoskeleton is inarticulated (Figures 2E, 3B), composed of the centripetal apical actines of the cortical tetractines and the unpaired actines of the few subatrial triactines. Occasionally the apical actine of the tetractines attains the atrial skeleton. The atrial skeleton is composed of tetractines with the apical actine free in the atrial lumen (Figure 2F).

At the basis of the sponge body, the diameter of the atrial cavity decreases progressively, forming a blind end at the beginning of the peduncle (Figures 3C, E). The choanoskeleton is here reduced and disorganised and in the proximal part of the peduncle it is substituted by a dense mass of spherical cells hardly larger than choanocytes (Figure 3C).

The external skeleton of the peduncle is similar to the cortical skeleton of the body (Figure 3D). However, whilst tetractines are predominant in the body, triactines are predominant in the external skeleton of the peduncle (Figures 3B, C). A very thick fur-like layer of thin trichoxeas covers all the peduncle, turning the cortical layer of tangential spicules externally invisible (Figure 3F). The internal part of the peduncle is a dense meshwork of stout triactines arranged without order, giving to it a great rigidity (Figure 3C). At the base, the peduncle forms a rather large, sometimes lobated basal plate, fixed at the surface of the substrate (Figure 3A).

Spicules (Figure 4, Table 1). Trichoxeas: Very thin, fusiform with sharp tips. They are straight or slightly curved (Figures 4A, B).

Cortical triactine (Figure 4C): Sagittal. Actines are conical and sharp. The unpaired actine is longer than the paired ones. The paired actines sometimes have different lengths.

Cortical tetractines (Figure 4D): Sagittal. Actines are conical and sharp. The unpaired actine is shorter than the paired ones. The apical actine is the longest actine. It is straight, conical and sharp.

Subatrial triactines (Figure 4E): Sagittal. Similar to the cortical triactines, but smaller.

Atrial tetractines (Figure 4F): Sagittal. Actines are conical and sharp. The unpaired actine is longer than the paired ones. The apical actine is shorter than the basal ones, cylindrical, sharp, smooth, and sometimes slightly curved.

Ecology. Specimens were found from 6 to 13 m of depth. The species was abundant in Serraria Island, Saco do Poço and Saco da Ponta Grossa (São Sebastião, São Paulo State) and specimens collected in these localities were found exposed to the sunlight, frequently with algae. Some specimens were attached to hydroids and others were epibiont on Tedania ignis.

Distribution. São Sebastião (São Paulo State) and Arraial do Cabo (Rio de Janeiro State), SE Brazil.

Spicule Actine Length (µm) Width (µm) n

Min Mean sd Max Min Mean sd Max UFRJPOR 5802 (H)

Trichoxeas 21.9 40.9 15.8 87.5 1.2 1.6 2.0 12.1 30 Cortical triactines paired 120.0 156.0 20.1 225.0 10.0 13.7 2.0 15.0 30 unpaired 175.0 223.3 28.4 270.0 10.0 15.1 2.9 22.5 30 Cortical tetractines paired 120.0 179.5 32.3 250.0 10.0 19.2 4.5 30.0 30 unpaired 120.0 238.5 58.2 350.0 10.0 22.5 4.3 30.0 26 apical 170.0 288.8 53.9 400.0 15.0 20.2 3.6 25.0 30 Subatrial triactines paired 50.0 88.8 15.7 115.0 5.0 7.8 1.2 10.0 30 unpaired 105.0 179.8 38.2 250.0 5.0 8.3 1.9 12.5 30 Atrial tetractines paired 55.0 81.3 10.1 100.0 7.7 5.0 1.5 10.0 30 unpaired 95.0 115.2 13.2 145.0 7.5 5.0 1.5 10.0 30 apical 50.0 69.4 10.8 95.0 5.0 7.8 1.2 10.0 30 UFRJPOR 5801 (P)

Trichoxeas - - - - - - - - - Cortical triactines paired 110.0 156.0 31.0 220.0 15.0 18.2 2.8 25.0 30 unpaired 190.0 249.0 43.4 350.0 10.0 19.3 3.4 25.0 30 Cortical tetractines paired 170.0 211.7 26.7 270.0 20.0 26.2 5.0 35.0 30 unpaired - - - - - - - - - apical 200.0 284.3 50.4 370.0 20.0 27.3 5.8 35.0 30 Subatrial triactines paired 50.0 86.7 16.9 120.0 10.0 10.0 0.0 10.0 30 unpaired 80.0 142.3 31.9 190.0 10.0 10.0 0.0 10.0 30 Atrial tetractines paired 50.0 67.9 8.7 87.5 7.5 8.8 1.3 10.0 17 unpaired 87.5 101.0 12.9 130.0 7.5 9.0 1.1 10.0 17 apical 25.0 49.8 13.9 80.0 6.3 8.0 1.5 12.5 16 Remarks. Until now only three species of Amphoriscus with peduncle were known: A. chrysalis, A. cyathiscus and A. testiparus. Amphoriscus chrysalis is a species from the Adriatic Sea. It can be differentiated from the new species by the absence of trichoxeas and cortical triactines and by the presence of subatrial tetractines (the new species has only subatrial triactines). Amphoriscus cyathiscus, from Australia, can be differentiated from A. pedunculatus sp. nov. because it has no cortical trichoxeas and tetractines and it has subatrial tetractines instead of triactines. Amphoriscus testiparus is a species from Cuba and it differs from A. pedunculatus sp. nov. mainly by the absence of trichoxeas and presence of subatrial tetractines.

Considering the species without peduncle, A. pedunculatus sp. nov. is easily distinguished from A. cylindrus, A. kryptoraphis, A. oviparus, A. salfii, A. synapta and A. urna by the presence of tetractines in the subatrial skeleton, absent in A. pedunculatus sp. nov.

Amphoriscus ancora, A. bucchichii, A. elongatus, A. gregorii and A. semoni have only triactines in the subatrial skeleton, as A. pedunculatus sp. nov., however, they can be easily differentiated by other features. Amphoriscus ancora does not have cortical triactines and trichoxeas and it has root-tufts. Amphoriscus bucchichii, A. gregorii and A. semoni do not have cortical triactines. Amphoriscus elongatus has subregular cortical tetractines and its spicules are larger than those of A. pedunculatus sp. nov. [A. elongatus —cortical triactine: 250/22 (paired), 450/15 (unpaired), cortical tetractine: 600/70 (basal), 600–700/70 (apical); subatrial triactines: 300/20 (paired), 380–450/20 (unpaired); atrial tetractine: 250/16–20 (paired), 450/16–20 (unpaired), 180/16–20 (apical). Amphoriscus pedunculatus sp. nov. —cortical triactine: 120–225/10–15 (paired), 175–270/10–23 (unpaired), cortical tetractine: 120–250/10–30 (paired), 120–350/10–30 (unpaired), 170–400/15–25 (apical); atrial tetractine: 55–100/8–10 (paired), 95–145/8–10 (unpaired), 50–95/5–10 (apical)].