Asbestopluma (Asbestopluma) bharatiyae Rengaiyan & Ingole 2022, sp. nov

Asbestopluma (A.) bharatiyae sp. nov. Figures 4–5, Table 2 Material examined. Holotype. NCPOR /HYD-IOCIR/0034, seamount of the Central Indian Ridge, Indian Ocean, 23° 9’ 47.88’’ S, 69° 31’ 51.96’’ E, 1917 m, MGS Sagar, cruise no: MGS 35A, MGS-35A, 05 April 2020, Benthic Sledge, Coll. Periasamy R, samples in 70% ethanol, sample MGS_35A_BD21(D). Paratype. NCPOR /HYD-IOCIR/0035 same collection details as for holotype. Etymology. The species name “ bharatiyae ” refers to the Bharat Dynasty. In the ancient era, Emperor Bharat (India) gave his name to the dynasty, referred to as Mahabharat or Akhand Bharat. Gender is feminine. Distribution. Asbestopluma (A.) bharatiyae sp. nov. is known only from its type locality in the seamounts of the Central Indian Ridge system. Diagnosis: The holotype is a live sponge attached to dead coral, having a dichotomously branched main stem 0.4–0.8 mm wide. The holotype is 60.5 mm long, and the axis is 0.6 mm wide. The main axis surface tissue is somewhat uneven and covered with a mass of short fine fibers (Figure 4A). Description. Shape and size: The holotype has a dichotomously branching stem of 14 mm in length and 0.8 mm in width at the base area and 0.4 mm wide in the upper area. Tightly set filaments on both sides of its bifurcating habit. The paratype consists of three smaller fragments 5–8 mm in length with similar morphology to the holotype. White colour when preserved (Figure 4A). Skeleton: The axis of the main stem is composed of longitudinally tightly bound arranged mycalostyles (Figure 4B). A layer of confusedly aligned axes of subtylostyles forms the outer cortex with an uneven surface of the main stem and contains abundant large anisochelae and sigmas. The numerous filaments, composed of subtylostyles, are placed at right angles pointing somewhat apically that are shorter than those mycalostyles (Figure 4C). Foraminifera a prey, entangled in the filament is seen in Figure 4D. The smaller anisochelae are rare in the main stem; abundant large anisochelae cover both the stem and the filament-bearing upper stem (Figure 4E). The small anisochelae are very abundant and are found covering the filaments (Figure 4F–G). Mycalostyles: Slightly curved, fusiform, size range: 574.4–(724.2)–851.9 µm long, 16.4–(20.4)–29.78 µm wide (Figure 5A, Table 2). Subtylostyles: straight, size range: 297.8–(362.6)–553.1 µm long, 8.7–(11.6)–14.4 µm wide (Figure 5B). Anisochelae I: Head of anisochelae with large lateral alae attached to the shaft along about two-thirds of their length, with a sizeable frontal ala, ovoid. The shaft is weakly curved in the first part and has two small fimbriae close to the foot. Size range: 24.5–(32.7)–36.65 µm, shaft diameter 4.3–5.4 µm (Figure 5C–F). ......continued on the next page TABLE 2. (Continued) ......continued on the next page TABLE 2. (Continued) ......continued on the next page TABLE 2. (Continued) ......continued on the next page TABLE 2. (Continued) Anisochelae II: Numerous, covering rare in the main stem and very abundant in the filaments, curved shaft, and upper tooth in the central part about half the total length of the anisochelae, and lateral upper alae covering about 80% of the shaft. The lower end of the anisochelae is in the form of two small plates with a central part of the anisochelae, size range: 4.5–(5.1)–6.4 µm (Figure 5G–H). Sigmancistras: Contorted, concave side flattened, size range: 19.84–(22.9)–27.7 µm (Figure 5I–J). Molecular data. GenBank accession number, 28S: MW810078, mtCOI: MW868386. Remarks. In terms of spicule measurements of A. (A.) bharatiyae sp. nov. is closely related to A. (A.) jamescooki Hestetun, Rapp & Xavier, 2017, described earlier from seamounts in the Southwest Indian Ocean Ridge (Hestetun et al. 2017a), and A. (A.) desmophora Kelly & Vacelet, 2011 which was initially described from seamounts along the Macquarie Ridge in the vicinity of New Zealand, and subsequently recorded from seamounts in the eastern Solomon Islands (Vacelet & Kelly 2014). Asbestopluma (A.) bharatiyae sp. nov. differs from A. (A.) desmophora in lacking desmas, and acanthosubtylostrongyles (which appear to be unique in the latter species compared to other members of the genus), and in the shape of the two types of anisochelae. The larger anisochelae in A. (A.) desmophora and A. (A.) jamescooki are triangular and their upper ends are palmate, while in A. (A.) bharatiyae sp. nov. upper end of the anisochelae is more rounded, with major notches between alae and the shaft of the anisochelae (Figure 5G–H). The smaller palmate anisochelae are more rounded and with the alae covering the shaft in A. (A.) jamescooki than in A. (A.) desmophora. The same general spicule morphology in A. (A.) jamescooki from the SWIOR, from which A. (A.) bharatiyae sp. nov. species from the CIR can be distinguished by geographical distance, general habitus, and other spicule measurements (Table 2). A. (A.) bharatiyae sp. nov. species has bifurcating habit similar to A. (A.) furcata Lundbeck, 1905, A. (A.) jamescooki, and A. (A.) ruetzleri Hestetun, Tompkins-Macdonald & Rapp, 2017 species, but these species differ from the others by the different shapes of anisochelae. Molecular data based on mtCOI and 28S genes from this species has been included in a phylogenetic tree which shows a separate branch of A. (A.) bharatiyae sp. nov. and sister group to A. (A.) jamescooki with high bootstrap support (87) than in A. (A.) desmophora.
Published as part of Rengaiyan, Periasamy & Ingole, Baban, 2022, Three New Carnivorous sponge species (Demospongiae: Cladorhizidae) from the Seamounts of the Central Indian Ridge, pp. 451-486 in Zootaxa 5162 (5) on pages 457-464, DOI: 10.11646/zootaxa.5162.5.1, http://zenodo.org/record/6816801
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