Iophon terranovae, Calcinai & Pansini, 2000
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publication ID |
https://doi.org/ 10.5281/zenodo.5757715 |
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persistent identifier |
https://treatment.plazi.org/id/03D2A011-FFE0-FFD8-A983-68BA504EFBC9 |
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treatment provided by |
Marcus |
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scientific name |
Iophon terranovae |
| status |
sp. nov. |
Iophon terranovae View in CoL n. sp.
( Figs 2 View FIG ; 3 View FIG )
MATERIAL EXAMINED. — Holotype: Faraglione, 100 m, 20.I.1994, POR275 ( MNA No. 1); paratype, 1989-1990 campaign, MOR 31 View Materials ( MSNG).
ETYMOLOGY. — The new species is named after the locality on the Ross Sea where the Italian Antarctic research station has been operating since 1987.
TYPE LOCALITY. — Terra Nova Bay, Faraglione, 74°42.2’S, 164°10.9’E.
DESCRIPTION
The holotype is a subcylindrical fragment, 7 cm high and 1.5 cm across, belonging to a presumably erect specimen. The paratype fragment ( Fig. 2A View FIG ) is 5 cm high and 3 cm wide and seems to be part of a massive specimen. The alcohol preserved sponge is dark brown but it becomes light beige outside and a little darker inside when dry. The sponge surface is smooth with a not easily detachable ectosome, 0.3-0.5 mm thick. The choanosome is rather cavernous. The consistency when wet is soft and elastic, but dry the sponge becomes crumbly, with a crusty ectosome whose edges tend to roll up. A single, slightly raised osculum, 0.4 mm in diameter, is detectable.
Skeleton
The ectosome is formed by a thick layer of acanthostyles arranged perpendicular to the surface ( Fig. 2B, C View FIG ). In the dry state, these spicules tend to assume a paratangential arrangement and form slightly diverging bunches. A few anisochelae and abundant bipocilla are enclosed in a very thin dermal membrane perforated by ostia. The ectosome is bound to the choanosome by spicule tracts formed by smooth acanthostyles and slen- der styles which form an irregular reticulation with elongated meshes and abundant interstitial spicules ( Fig. 2B, C View FIG ). Tracts, which are formed by five to eight spicules, become thicker toward the sponge surface. The palmate anisochelae are scattered, not grouped in rosettes. The tylotes are very rare in the spicule preparations and their position in the skeleton is not detectable.
Spicules
Oxeote-styles almost smooth, straight or gently curved and seldom malformed ( Fig. 3A View FIG ). Their basal extremity bears typically a mucron which can be straight or hooked, bifid or almost inconspicuous ( Figs 2F, G View FIG ; 3E View FIG ). The other end is alike or more or less acerate. The presence of a sub- terminal swelling is frequent and short, polytylote forms are not rare ( Fig. 3A View FIG ). The swellings may be finely spined and the terminal part of the styles may be seldom rugose. Single spines may be found at the basal end of the acanthostyles which measure 200-580 (431) × 18-24 (22) µm.
Slender styles, straight or curved, with a small, single spine on the head ( Fig. 3C View FIG ). They are rather numerous in the choanosome but almost absent in the ectosome. They are 375-540 (440) µm long and not more than 4-5 µm thick. They are generally considered to be juvenile spicules (Topsent 1907).
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Tylotes straight, with slightly swollen extremities ( Fig. 3B View FIG ). Very small spines are uniformly distributed on the tyles or restricted to the spicule extremities. These spicules are rare and were only found in the holotype. They measure 265-275 (270) × 7-10 (9) µm.
Palmate anisochelae, with the smaller end bearing a single or a bifid mucron ( Figs 2 View FIG H-L; 3D). They belong to a single size category and are 51-64 (57.3)µm long.The shaft is arcuate and7-8µm thick. Bipocilla almost closed, with a bent shaft and cup-shaped ends ( Figs 2D, E View FIG ; 3F View FIG ). The larger cup is finely toothed. They are very abundant and measure 9-15 (11.3) µm.
REMARKS
The new species is based on the presence of almost smooth spurred styles, large anisochelae, and very abundant bipocilla. It belongs to the group of Iophon devoid of true acanthostyles that was distinguished by Dendy (1924) under the generic name Iophonopsis , now abandoned (Desqueyroux-Faundez & Van Soest 1996). The numerous specimens of Iophon devoid of true acanthostyles (excluding I. proximum ) recorded along the coast of continental Antarctic are now commonly referred to three valid species (Sarà et al. 1992): I. unicornis Topsent, 1907 , I. radiatus Topsent, 1901 and I. aceratus Hentschel, 1914 . The first and the second ones were recorded from Terra Nova Bay (Pansini et al. 1994) and are sympatric with the new species. Iophon unicornis , which receives as synonym I. spatulatus Kirkpatrick, 1907 (see Koltun 1964; Boury- Esnault & Van Beveren 1982; Desqueyroux- Faundez & Van Soest 1996), has smooth, spurred styles resembling those of I. terranovae n. sp. but smaller in size, acanthostrongyles instead of acanthotylotes and anisochelae which are only 17 µm long (average) instead of 57 µm. Iophon radiatus has anisochelae as large as I. terranovae , even though they belong to two size categories, and similar bipocilla, but differs distinctly by shape and spinulation of the acanthostyles. Iophon radiatus sensu Desqueyroux (1972) , which is not a synonym of I. radiatus sensu Topsent (1901) (Desqueyroux-Faundez & Van Soest 1996) is rather close to the new species in spicule size, but has a very different shape. Iophon aceratus Hentschel, 1914 has smooth styles similar to those of I. terranovae n. sp. but differs by having distally spined strongyles instead of tylotes, anisochelae with very different extremities, and bipocilla with long tapered cup edges. Shape in these three Antarctic Iophon species is not a good
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distinctive character because all are more or less globular and have digitiform, branching outgrowths. The new species may be part of the “mucronate-oxeote-styles bearing species” (i.e. I. unicornis Topsent, 1907 , I. timidum Desqueyroux-Faundez & Van Soest, 1996 , I. tubiforme Desqueyroux-Faundez & Van Soest, 1996 , as suggested by the latter authors in their 1996 paper).
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