Antho (Acarnia) ridgwayi Stone & Lehnert & Hoff 2019, n. sp.

• Main Authors: Stone, Robert P., Lehnert, Helmut, Hoff, Gerald R.
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2019
• Subjects: Biodiversity; Taxonomy; Animalia; Porifera; Demospongiae; Poecilosclerida; Microcionidae; Antho; Bering Sea
• Online Access: https://doi.org/10.5281/zenodo.5944522; http://treatment.plazi.org/id/2C6287D2FFCFE975DC8BFB015B39FE66

Antho (Acarnia) ridgwayi n. sp. (Figs. 2 & 3; Table 2) Material examined. Holotype USNM2084685, largely intact specimen originally frozen then dried, collected by Jerry Hoff with a research survey bottom trawl from the FV Cape Flattery 21 June 2016, 210 m depth, haul station #27, 97.5 km WSW of St. Paul Island, Pribilof Islands, upper slope of the eastern Bering Sea (56°54.5880' N, 173°21.9390' W). Water temperature = 3.9 °C. A fragment of the holotype is deposited at the Zoologische Staatssammlung München, Germany under the registration number ZSM 20190188. Description. A foliaceous or flabellate, golden brown sponge with an irregular outline and lobes in several directions (Fig. 2A), maximum dimensions 130 x 120 x 2–3 mm. The consistency is flexible and resilient. No oscules visible, surface is smooth. Skeletal architecture. The relatively narrow sheet of the sponge has a reticulation of acanthostrongyles in its center (Figs. 2B & 3A), near the two surfaces, plumose tracts composed of two categories of styles rise towards the ectosome (Figs. 2B, 2C, & 3A). The smaller category of subtylostyles with microspined heads also occurs in bundles in between the tracts. The ectosome consists of a thin organic veneer (Figs. 2B & C) and contains abundant palmate isochelae, toxa and tylotes with microspined heads. Spicules. Megascleres are ectosomal tylotes with microspined heads (Fig. 3C), 223–254 x 6–9 µm, choanosomal acanthostrongyles (Figs. 3B & D), 195–228 x 14–24 µm, choanosomal, echinating smooth, thick styles (Figs. 2B, 2D, & 3B), 620–805 x 2 5–38 µm, and choanosomal thin (subtylo-)styles (Fig. 3B) with microspined heads, 378–466 x 8–10 µm. Microscleres are palmate isochelae (Fig. 3F), 20–24 µm and toxa in two size categories, small, 10–42 µm, and large, 136–182 µm (Figs. 2D & 3E). Discussion. A well-structured choanosome with megascleres differentiated in geometry and distribution, more than one category of choanosomal megascleres, one greatly modified and accessory spicules that ...