Abyssocladia escheri Ekins & Erpenbeck & Hooper 2020, sp. nov.

Abyssocladia escheri sp. nov.

Figure 2, Tables 1 & 2

urn:lsid:zoobank.org:act: 49779C5D-8130-4573-808D-1CAB9F5469CE

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15–30 x 2Main axis tight bundles of mycalostyles, basal part also with strongyles, spicules in filaments perpendicular between stem bundles, terminal branches scattered stylesmycalostyles 465–(831)–2023 x 17.7–(24.4)–41.3styles 283–(338)–400 x 4.2–(6.3)–9.8strongyles 164-(289)-431 x 11.2-(16.8)- 23.9Arcuate isochelae I, 4.8–(74.4)–91.5 Arcuate isochelae 2, 21.4-(32.4)-51.2 Abyssochelae, 25.7-(42.6)-54.88.3-(9.9)- 11.4absentSouthwestern Indian Ocean Ridge, off South Africa, bathyal

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subtylostyles (peduncle axis) 450–510 x 8–10 subtylostyles (body) 320–420 x 6–8 monocrepedial desmas 320–420 x 10–20undifferentiated from axisundifferentiated from axisarcuate isochelae 60–85absent30–40 x 2continental slope, off Townsville region Great Barrier Reef, bathyal

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mycalostyles 530-(689)-940 x 14.1-(20.7)- 29.8base missingarcuate isochelae 48.7–(61.2)- 67.5 arcuate iso-or cleistochelae 22.0–(25.6)- 336.3-(6.4)- 7.9absentMid-Atlantic Ridge- Fracture Zone intersection, bathyal

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undifferentiatedbase missingarcuate isochelae 20.3-(30.8)- 56.75.3-(6.9)- 10.311.0-(16.1)- 22Southwestern Indian Ocean Ridge, off South Africa, bathyal

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mycalostyles 1262–2321 x 19–33subtylostyles 1018–1994 x 20–35 tylostyles 275–592 x 6–15undifferentiated arcuate isochelae 78–13222–32absentMarianas, NW Pacific, abyssal

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15–60 x 2–3Peduncle with interlocked strongyles (the larger style-like), stem has a core of ascending styles with tangential bundles projecting with points outwardsmycalostyles -styles 409–1034 x 10–35undifferentiatedstrongyles 56–640 x 9–43arcuate chelae 45–79 abyssochelae 22–408–19absentDrake Passage seamounts, South America, mesophotic -bathyal

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mycalostyles 1, 1350-(1657)- 1940 x 19-(34)-26.5 microstrongyles 14-(64)-250 x 4-(6)-10mycalostyles 2, 395-(1016)-1790 x 10-(16)-24substrongyles 395-(642)-980 x 22-(36)-45cleistochelae- abyssochelae 38-(54)-751, 20–23 2, 9–12absentIzuOgasawara Arc, Japan, mesophotic

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mycalostyles 720-(933)- 1070 x 14-(17)-22subtylostyles- mycalostyles 430-(686)-960 x 5-(10)-13 strongyles 380-(568)-780 x 15-(18)-22base missingarcuate isochelae 28-(43)-509.4–(9.8)–11absentMuir Seamount, Bermuda, bathyal

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Cleistochelae 42.4-(47.4)- 55 Abyssochelae 11.0-(12.1)- 14.16.3-(6.6)-7.9absentMid-Atlantic Ridge-Fracture Zone intersection, bathyal

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subtylostyles 718–1443 x 14–25 tylostyles 2, 154–488 x 4–15tylostyles 1, 549–1356 x 7–19undifferentiatedCleistochelae, 8–12 arcuate isochelae 31–90absentMarianas, NW Pacific, bathyal

Material examined: Holotype: QM G337545, off Fraser Island, Station 115, Queensland, Australia, 25 o 19’31.1”– 25° 21’ 4.7” S, 154 o 4’5.9”– 154° 4’ 33.6” E, 2350– 2342 m, Beam Trawl, Coll. Merrick Ekins on RV Investigator, Cruise IN2017_ V03, Sample 115–126, 11/vi/2017.

Paratypes: QM G337546 off Fraser Island, Station 115, Queensland, Australia, 25 o 19’31.1”– 25° 21’ 4.7” S, 154 o 4’5.9”– 154° 4’ 33.6” E, 2350– 2342 m, Beam Trawl, Coll. Merrick Ekins on RV Investigator, Cruise IN2017_ V03, sample 115–144, 11/vi/2017; QM G337506 same collection data as QM G337546, Sample 115–144.1; QM G337507 same collection data as QM G337546, Sample 115–144.2.

Etymology: Named after the Dutch artist Mauritus Cornelis Escher, 1898–1972, for the shape of the abyssochelae resembling a 3D puzzle similar to something that Escher might have illustrated.

Distribution: This species is presently known only from the type locality off Fraser Island, Queensland, Australia, at abyssal depth.

Description: Growth form: Erect, pedunculate sponges up to 305 mm long and 20 mm thick at the widest part of the body, anchored in muddy substrate by a multi-furcate rhizoid basal root, with a club-shaped to conical, fleshy body and long, irregularly branching filaments that extend laterally at the apex of the sponge. The stem is up to 250 mm long and only 0.15 mm wide. The main body including filaments is 39 mm in length, and including the filaments 20 mm wide. The filaments themselves are up to 10 mm in length and 0.5 mm in width. The remainders of the basal rhizoid rootlets are 15 mm long and 0.3 mm wide.

Colour: Pale cream to orange on deck and beige in ethanol.

Ectosomal skeleton: The ectosome of both the stem and the filaments consists of soft tissue encrusted with abyssochelae.

Endosomal skeleton: The body, filaments and axis of the stem are composed of tightly bound, long, thin mycalostyles longitudinally arranged. The basal rhizoid rootlet also consists of longitudinally aligned axes of substrongyles that are shorter than those styles in the remainder of the sponge.

Megascleres: Mycalostyles in the filaments and stem are long, thin and straight with sharp points (615– 1280 x 7.0– 15.2 µm). Substrongyles from the roots are shorter and thicker, sometimes curved, often with blunt ends (92–555 x 3.4–16.7 µm) (see Table 2).

Microscleres: Abyssochelae with curved shaft (18.4–53.1 x 10.2–24.0 µm). In the smaller abyssochelae, the frontal and lateral alae are usually in contact with the alae offset from the opposing ones. In larger abyssochelae these alae become separated from those opposing alae. Abyssochelae of intermediate sizes were also present (see Table 2).

Molecular data: The 28S sequence of QM G337545 and G337546 are provided in the Sponge Barcoding Database under accession number SBD#2302, SBD#2303 respectively and the molecular difference to other congenerics displayed in Figure 3.

Remarks: The presence of abyssochelae indicates this species belongs to the genus Abyssocladia. On gross morphology alone most species within this genus fall into three groups: ‘centipedes’ (feather-shaped), ‘bottlebrushes’ (short peduncle, large body), or ‘lollypops’ (with long pedunculate stems). The pedunculate species include A. bruuni Lévi, 1964, A. carcharias Kelly & Vacelet, 2011, A. claviformis Koltun, 1970, A. desmophora (Hooper & Lévi, 1989), A. dominalba Vacelet, 2006, A. fryerae Hestetun et al., 2019, A. huitzilopochtli Vacelet, 2006, A. inflata Vacelet, 2006, A. kellyae Hestetun et al., 2019, A. lakwollii Vacelet & Kelly, 2014, A. marianensis Hestetun et a l., 2019, A. natushimae Ise & Vacelet, 2010, A. oxeata Koltun, 1970, A. polycephalus Hestetun et al., 2016 c, A. stegosaurensis Hestetun et al., 2019 and A. villosa. Abyssocladia that resemble ‘centipedes’ include: A. atlantica Lopes & Hajdu, 2014, A. corniculiphora Hestetun et al., 2017a, A. diegoramirezensis Lopes et al., 2011, A. faranauti Hestetun et al., 2015, A. leverhulmei Goodwin et al., 2017, A. myojinensis Ise & Vacelet, 2010, A. naudur Vacelet, 2006, A. tecta Hestetun et al., 2015, and A. umbellata Lopes et al., 2011. The third group, resembling ‘bottlebrushes’, include A. boletiphora Hestetun et al., 2017a, A. flagrum (Lehnert et al., 2006), A. hemiradiata Hestetun et al., 2017a and A. symmetrica (Ridley & Dendy, 1886). There is a solitary species that has a ‘bush-shaped’ anastomosing branched morphology representing multiple peduncles: A. koltuni (Ereskovsky & Willenz, 2007).

Abyssocladia escheri sp. nov. is unique amongst this genus in its relatively large size (up to 30 cm total length, exceeded only by A. flagrum from the Aleutian Islands, which measures 54 cm in length); having reduced spiculation consisting only of styles as megascleres and abyssochelae as microscleres; and comparative spicule dimensions (see Table 1). The abyssochelae of A. escheri sp. nov. resemble in shape those of A. natushimae from the North Pacific. However the abyssochelae in this new species are much smaller than those of A. natushimae (18.4-(29.3)- 53.1 µm vs. 38-(54)- 75 µm, respectively), and additionally A. escheri sp. nov. lacks the sigmancistras and microstrongyles that are present in A. natushimae.