Hymeniacidon torquata Topsent, 1916

Fernandez, Julio C. C., Bravo-Gómez, Diego, Cárdenas, César A. & Hajdu, Eduardo, 2020, Sponges from Doumer Island, Antarctic Peninsula, with description of new species of Clathria (Axosuberites) Topsent, 1893 and Hymeniacidon Bowerbank, 1858, and a re-description of H. torquata Topsent, 1916, Zootaxa 4728 (1), pp. 77-109 : 83-86

Hymeniacidon torquata Topsent, 1916

( Tables 1–3 ; Figures 2–5 )

Type locality. Petermann Island (65°10’ S, 64°08’ W), WAP ( Topsent 1916) .

Material examined. All material was collected by C. a. Cárdenas from South Bay, Doumer Island ( WAP) : MNRJ 20625 , 20630 , (P1, 64°52’28.1’’ S, 63°34’36.0’’ W), 10 m depth, 11 Jan 2016 ; MNRJ 20635 , 20637 , P1, 20 m depth, 13 Jan 2016 ; MNRJ 20649 , (P2, 64°52’16.4’’ S, 63°33’51.6’’ W), 10 m depth, 12 Jan 2016 ; MNRJ 20667 (P4, 64°51’58.6” S, 63°37’46.7” W), 10 m depth, 19 Jan 2016 ; MNRJ 20674 , 20678 , 20679 , 20680 , P4, 20 m depth, 18 Jan 2016 ; MNRJ 20689 , 20690 , 20693 , P1, 10 m depth, 29 Jan 2016 ; MNHNCL Por-15034, 15036, P1, 20 m depth, Jan 2017 ; MNHNCL Por-15039, 15041, P2, 10 m depth, Jan 2017 ; MNHNCL Por-15047, 15050— 2 specimens, P4, 10 m depth, Jan 2017 ; MNHNCL Por-15052— 2 specimens, P4, 20 m depth, Jan 2017 ; MNHNCL Por-15056, 15057— 4 specimens, 15058 (P7, 64°52’47.4” S, 63°35’50.8” W), 20 m depth, Jan 2017 ; MNHNCL Por-15061— 2 specimens, P1, 10 m depth, Jan 2018 ; MNHNCL Por-15069— 2 specimens, P1, 20 m depth, Jan 2018 ; MNHNCL Por-15074, P2, 20 m depth, Jan 2018 ; MNHNCL Por-15077, 15078, 15079, P4, 20 m depth, Jan 2017 ; MNHNCL Por-15082, P7, 10 m depth, Jan 2018 ; MNHNCL Por-15083, P7, 20 m depth, Jan 2018 ; MNHNCL Por-15086, P7, 20 m depth, Jan 2018 ; MNHNCL Por-15088— 2 specimens, P1, 20 m depth, Jan 2017 ; MNHNCL Por-15089, P4, 20 m depth, Jan 2017 ; MNHNCL Por-15090, P7, 10 m depth, Jan 2017 ; MNHNCL Por-15091— 3 specimens, P7, 20 m depth, Jan 2017 ; MNHNCL Por-15092, P1, 10 m depth, 11 Jan 2018 ; MNHNCL Por-15093, P7, 20 m depth, 11 Jan 2018 ; MNHNCL Por-15094— 2 specimens (P8, 64°51’53.40’’ S, 63°37’36.15’’ W), 10 m depth, 11 Jan 2018 ; MNHNCL Por-15096 (P9, 64°52’12.0’’ S, 63°33’50.5’’ W), 20 m depth, 11 Jan 2018 .

Comparative material. ZMH S 2343, Hymeniacidon spec. Hentschel (1914: 125), off Wilhelm II Coast, Davis Sea (East Antarctica), 3397 m depth, March 1903, collection Gauss, coll. Deutsche Südpolar Expedition, 1901–1903.

Diagnosis. Hymeniacidon from Antarctica (shallow water) with encrusting to massive habit, oscules on ridges, irregular surface, bright-yellow color in vivo and a single category of (subtylo)styles, 240–585 × 4.2–14 µm (emended from Topsent 1916, 1917).

Description. Habit, massive with some encrusting parts ( Figs. 2 A–G). In the conserved material, body rather cavernous. Surface, microhispid, very irregular, rugose to verrucose. Surface with a membrane not easily removable (viz., removable in flakes), bordering (specimens in vivo) or partially recovering oscules (specimens in preservative). Oscules, scattered, usually at the top of volcano-like elevations (up to 0.5 cm high from specimens in vivo) or just on the surface, ca. 5 mm in diameter (specimens in vivo) and ca. 2 mm in diameter (specimens in preservative). Pores, several and scattered. Consistency, compressible and slightly brittle. Color, in vivo bright yellow, pale orange after collection (exposed to the air) and pale-beige to dirty-beige in preservative. A few specimens with a light-brown color in preservative too ( Figs. 3 A–I).

Skeleton. Choanosomal region with several well-structured, ascending, multispicular tracts of styles in a reticulation. Ectosomal region with bundles of styles piercing the surface slightly. Further, bundles of styles in a (para)tangential arrangement on the surface or fanning out in bouquets or brushes beneath the surface. Usually adjacent bouquets and/or brushes slightly overlap. Several wide and round canals in choanosomal and subectosomal regions, usually up to 500 µm diameter in the former, and 300 µm diameter in the latter ( Figs. 4 A–E).

Spicules. Megascleres ( Tables 2–3 ): Styles to subtylostyles ( Figs. 5 A–F), curved to slightly sinuous, slightly fusiform and smooth. Base, usually slightly swollen, sometimes with knob (one or more) on the swelling. Tip, usually acerate: 240– 410.7 (59.7)–585 × 4.2– 10.5 (1.6)– 14 µm. Juveniles forms slender.

Ecology, bathymetry and distribution. Specimens occur on hard substrates, which are normally covered by encrusting calcareous algae. Many specimens were associated with brown, red algae and bryozoans. The species is common in South Bay at Doumer Island, WAP. It occurs in shallow water, 25 m depth ( Topsent 1908, 1916, 1917; Koltun 1964), and 10 and 20 m depth from the present study. It occurs in WAP: Graham Coast ( Koltun 1964), Anvers Island ( Topsent 1908), Petermann Island—type locality ( Topsent 1916, 1917), and Doumer Island (present study).

Remarks. The habit, skeleton, type of spicules as well as measurements of spicules of the material analyzed fit the original description of H. torquata . Although this species has been recorded in WAP by previous studies ( Topsent 1916, 1917; Koltun 1964), we present re-description based on in situ photos and a large series of specimens; n= 51 (total examined) and n= 13 (with spicules measurements). Presently described materials are nearly topotypical; Petermann Island (the type locality) is only ca. 41 km. We feel thus appropriate to propose an amended diagnosis for the species (see above), so it can be easier to recognize it in the field.

Hymeniacidon torquata is a shallow water species from the Antarctic Peninsula ( Topsent 1908, 1916, 1917; Koltun 1964; and present study), recorded only down to 25 m depth. However, Topsent (1916, 1917) mentioned a possible occurrence in very deep waters (3397 m) from East Antarctica; have suggested the material from the Gauss scientific collection named as Hymeniacidon spec. by Hentschel (1914: 25) might belong in this species. We have, nevertheless, examined the latter and it does not fit in H. torquata . Rather, we believe this specimen to belong in a new species, which we propose and describe below.

Figures

FIGURE 2. Hymeniacidon torquata Topsent, 1916, habit (specimens in situ): A, specimen MNRJ 20667; B, specimen MNRJ 20689; C, specimen MNRJ 20693; D, specimen not collected; E, specimen not collected; F, specimen not collected; G, surface detail of the same specimen in “ F ”. Scale bars:A = 20 cm; B = 5 cm; C = 5 cm; D = 10 cm; E = 0.5 cm; F = 5 cm; G = 0.5 cm. Photographs by Dr. Cristian Lagger.

FIGURE 3. Hymeniacidon torquata Topsent, 1916, specimens (in conservative). A–C, MNRJ 20667; D–F, 20626; G–I, 20649. A, D, G, freshly collected specimens with a pale orange color. B, C, E, F, H, I, ethanol preserved specimens. A, pale orange specimen, white arrow point to a red alga and black arrow point to a polychaete tube; B, E, transverse section showing the cavernous choanosome; C, F, I, surface with several scattered small pores; H, damaged surface exposing cavernous choanosome.

FIGURE 4. Hymeniacidon torquata Topsent, 1916, skeleton: A, transverse section in MNRJ 20667 showing loose choanosomal ascending tracts obscured by the overlaid halichondroid architecture, ending in surface bouquets; B, transverse section in MNRJ 20689 showing ectosomal bouquets; C, same as B, but in MNRJ 20693; D, transverse section in MNRJ 20689 showing loose choanosomal ascending tracts obscured by the overlaid halichondroid architecture; E, same as “ D ”, but in MNRJ 20693. Scale bars: A–E = 300 µm.

FIGURE 5. Hymeniacidon torquata Topsent, 1916, spicules: A, styles of MNRJ 20667; B, bases of styles of MNRJ 20667, in detail; C, styles of MNRJ 20689; D, bases of styles of MNRJ 20689, in detail; E, styles of MNRJ 20693; F, bases of styles of specimen MNRJ 20693, in detail. Scale bars: A, C, E = 100 µm; B, D, F = 10 µm.