Asbestopluma (Asbestopluma) indiyansis, Rengaiyan & Ingole, 2022

Rengaiyan, Periasamy & Ingole, Baban, 2022, Three New Carnivorous sponge species (Demospongiae: Cladorhizidae) from the Seamounts of the Central Indian Ridge, Zootaxa 5162 (5), pp. 451-486 : 454-457

Asbestopluma (Asbestopluma) indiyansis sp. nov.

Figures 2–3 , Table 2

Material examined. Holotype. NCPOR /HYD-CIR/0031, seamount of the Central Indian Ridge , Indian Ocean, 23° 09’ 47.88’’S, 69° 31’ 51.96’’E, 1917 m, 05 April 2020, Benthic Sledge, Coll. Periasamy R, samples in 70% ethanol, MGS Sagar, cruise MGS-35, Sample MGS_35A_BD21(A).

Paratype. NCPOR /HYD-CIR/0032 collection details same as holotype , NCPOR /HYD-CIR/0033 collection details same as holotype .

Etymology. This species name “ indiyansis ” refers to the country ( India). Gender is feminine.

Distribution. Species A. (A.) indiyansis sp. nov. is presently known only from the type locality (seamounts of the Central Indian Ridge).

Description.

Shape and size. The elongated holotype (NCPOR/HYD-CIR/0031) is attached to the dead coral. Holotype forms an unbranched, slender spicular axis arranged at right angles around the main stem. It consists of several bundles of longitudinal mycalostyles forming the main axis among rows of finner filaments tightly placed in all directions with a disc-shaped basal attachment ( Figure 2A ). The main stem of the sponge is protected by subtylostyle projecting at right angles. It measures 10.2–11.4 cm in total length, with the sponge body 2.8–3.1 mm in diameter. Colour in life is beige, whitish beige when preserved in ethanol. Paratype NCPOR/HYD-CIR/0032 has an unbranched, slender spicular axis and it has a total length of 54.3 mm, a diameter of 3.1 mm. The colour in life is beige. Paratype NCPOR/HYD-CIR/0033 is very similar to the holotype, 62.6 mm in length, with a diameter of 2.3 mm. The colour is life beige scuro when preserved ( Figure 2A–B ).

Skeleton. The main axis of the stem consists of tight bundles of mycalostyles arranged longitudinally with more tissue densely packed in the center. The axis of the filaments ( Figure 2C ) is supported by rays of mycalostyles placed in a radial pattern and anchored in the main stem. In cross-section, the stem consists of widely spaced bundles of mycalostyles, with a tiny core ( Figure 2B–F ).

Mycalostyle. Spicules of the main axis at the core of the stem, abruptly pointed, size 1089–(1240)–1389 µm long and 32.6–(36.5)–40.4 µm wide ( Figure 3A , Table 2 ).

Subtylostyles. Spicules of lateral filaments or body, straight, fusiform, size 258.8–(288.8)–315.4 µm long and 7.7–(9)–10.1 µm wide ( Figure 3B ).

Desmas. Monocrepid, 551–(588)–808 × 25–(47.1)–75 ( Figure 3C ).

Anisochelae I. Numerous, somewhat curved shaft, 70% of the total length covering the primary tooth, alae, three dorsal processes of anisochelae within the lower end, and 30% of the full size covering two well-developed frontal teeth. The upper tooth in the central part of the spicule and lateral alae reach down almost touching the lower end. The foot of the anisochelae is developed into two diverging alae, while the central part has three teeth. The size is 42.9–47.1–51.1 µm long ( Figure 3D–E ).

Anisochelae II. Nearly spherical, the head consisting large lateral alae close to the shaft down their whole length, with a shaft strongly curved bearing two large triangular lateral fimbriae, and smaller third fimbriae in the middle. 90% of the total length is covered with a central tooth and the lower end of the anisochelae has three dorsal processes, with 10% of the full size covered by two well-developed frontal teeth. Further, the main part’s upper tooth and lateral alae reach down to touch and fit between the lower alae. The foot of the anisochelae is developed into two small diverging alae. The size ranges 29.5–40.6 µm long ( Figure 3F–H ).

Anisochelae III. Curved shaft, with 70% of its total length covered by a central tooth, lateral alae, pointed bottom teeth, and claw-like alae at the lower end of anisochelae, with two rudimentary dorsal alae. The leaf-shaped plate of the central part has upwardly-pointed central alae about 1/6th of its total length, size 13.55–(18.34)–23.12 µm long ( Figure 3H–J ).

Sigmancistras. 90° contorted, internal margin compacted, size 20.2–(22.6)–25.1 µm long ( Figure 3I–K ).

Molecular data. GenBank accession number, 28S: MW810077 , mtCOI: MW868385 .

Remarks. This species has a single stem with filaments in rows which is common in the genus and the two types of anisochela and sigmancistras of microsclere spicules are also typical for Asbestopluma . The A. (A.) indiyansis sp. nov. species that most closely matches the habit and spicule complement and spicule morphology of A. (A.) pseudoisochela Hestetun, Rapp & Xavier, 2017 , A. (A.) pennatula (Schmidt, 1875) and A. (A.) cf. belgicae ( Topsent, 1901) . A. (A.) indiyansis sp. nov. differs from other known species by having two types of anisochelae ( Figure 3C–E ). The new species appears similar morphology to that of the distal parts of A. (A.) pseudoisochela from the SWIOR but differs in having the desmas branching forms. The new species is also similar to A. (A.) cf. belgicae from the Southern Ocean and Southeastern Atlantic ( Koltun 1964, Topsent 1901). This new species is unique among the known Asbestopluma species by a combination of its morphology and the unique shape of its anisochelae, and they are roughly spherical. Asbestopluma (A.) bitrichela Bravo & Hajdu, 2011 , A. (A.) desmophora Kelly & Vacelet, 2011 , A. (A.) inexpectata Lopes & Hajdu, 2014 , A. (A.) indiyansis sp. nov. and A. (Helophloeina) stylivarians (Topsent, 1929) have an unusual desmas and all branching forms. This new species can be distinguished from these species most easily by different spicule morphology and sizes for the smaller megascleres and microsclere.

Molecular data from A. (A.) indiyansis sp. nov. species was included in a phylogeny of closely related Asbestopluma species. The phylogeny of new species is closely related to A. (A.) pseudoisochela with high bootstrap support (100%), A. (A.) pennatula , and A. (A.) cf. belgicae based on mtCOI and 28S genes.

Figures

FIGURE 2. Asbestopluma (Asbestopluma) indiyansis sp. nov. A. Holotype (NCPOR/HYD-CIR/0031). B. Arrows indicate the filament emerging from between the longitudinally arranged bundles of mycalostyles, and to the filament bases. C. SEM of the base of the stem. D–E. Organization of the anisochelae and the underlying mycalostyles. F. Cross section of the stem showing the oxeas and isochelae forming the ectosomal layer of the stem.

FIGURE 3. Asbestopluma (Asbestopluma) indiyansis sp. nov. A. Mycalostyle. B. Subtylostyle. C. Desmas. D–E. Anisochela I front and back view. F–H. Anisochela II front and back view. I–K. Anisochela III, L–N. Sigmancistras including an immature stage (K).