Figure 6, Table 4
urn:lsid:zoobank.org:act: EC21238B-C8A3-461F-B58D-23BFAC13ABBC
Material Examined: Holotype: QM G337488 off Jervis Bay, Station 56, New South Wales, Australia, 35 o 19’58.81”– 35° 19’55.2” S, 151 o 15’28.8”– 151°12’ 50.4” E, 2636– 2342 m, Beam Trawl, Coll. Merrick Ekins on RV Investigator, Cruise IN2017_ V03, Sample 56–236, 29/v/2017.
Etymology: Named ‘maxi’ for the maximum sized sigmas this species has, in addition to the usual small sigmas common amongst other species in the genus. The name also honours the family of the senior author, ‘Max Ekins I–IV’, of which I and II being great grandfather and grandfather respectively, and III and IV being father and brother respectively.
Distribution: This species is presently known only from type locality on the continental slope off Jervis Bay, New South Wales, Australia, at bathyal depth.
Description:
Growth form: An erect columnar pedunculate sponge with pinnate filaments projecting at right angles to the stem. This specimen is only 28 mm high, up to 2 mm wide, but the basal root and the top portion of the sponge are missing. On this station, the beam trawl was a fairly uniform muddy soft substrate. The filaments are up to 10 mm in length and 0.5 mm in width and project into four columns, with a right angle between them.
Colour: Pale cream on deck and in ethanol.
Ectosomal skeleton: The ectosome of both the stem and the filaments consist of soft tissue encrusted with anisochelae and sigmas. Endosomal skeleton: The axis of the stem and the filaments consists of tightly bound longitudinal tracts of mycalostyles. The mycalostyles are also arranged as buttresses providing support for the filaments that are also composed of the same styles and arise tangential to the stem (see Figure 6 H), so that at their ends the mycalostyles converge onto the filament mycalostyles. In addition there are supplementary smaller very fine and short filament columns composed of the subtylostyles projecting at right angles to the stem and similarly converging with buttressing mycalostyles.
axial styles 1550–2100 × 30–35 acanthotylo- strongyles 65–165 × 0.8–2.3 axial mycalostyles 370–780 × 8.5–17 acantho- tylostrongyles 65–165 × 0.8–2.3 styles- substrongyles 220–535 × 15–42 anisochelae 1, 32–36 x 4.1–5 anisochelae 2, 9.8–10.5 x 0.8–1 23–28 x 2.3 absent East Pacific Rise. Garrett Segment, bathyal...Continued on the next page
mycalostyles 1010-(1449)-2070 x 17.3-(24.2)-31.4 subtylostyles 610-(734)-880 x 11.0-(15.1)-18.8 strongyles 460-(659)- 830 x 3.1- (6.0)-9.4 acanthostyles 127–(198)- 250 x 1.5 palmate anisochelae 11.0- (12.7)-14.1 27.0-(30.7)- 34.5 absent Antarctica and western coast of Africa, bathyal...Continued on the next page
95–120 x 1 Dense spicular axis of mycalostyles- styles, outer layer of acanthotylostrongyles, filaments cored by subtylostyles mycalostyles-styles 1 500–1900 x 8–20 acanthotylostrongyles 100–500 x 1–3 subtylostyles 375–1300 x 10–25 absent palmate anisochelae 8–13 25–28 absent SE Pacific, Kermadec Trench, Coral Sea off New Caledonia, and NW Pacific off Aleutian Islands, bathyal-abyssal...Continued on the next page
83–109 x 1 Axis with longitudinally arranged mycalostyles, filaments of subtylostyles perpendicular to stem, basal stem with acanthotylostyles mycalostyles 990-(1194)-1426 x 18-(23)-33 acanthotylostyles 74-(114)-194 subtylostyles 320-(550)-660 x 8–(12)-14 absent anisocerci -chelae 52-(64)-74 Palmate anisochelae 8-(10)-12 19-(26)-34 absent Beata Ridge, Caribbean Sea, abyssal...Continued on the next page
10 Axis with tracts of polytylote tylostyles, filaments with shorter tylostyles polytylote tylostyles 275–990 x 5–24 smaller tylostyles absent arcuate anisochelae 25–28 71–104 absent NW Pacific, abyssal...Continued on the next page
60 x 0.5 Axis of stem with larger mycalostyles, bud-like filaments with smaller subtylostyles and also found on surface of stem mycalostyles 1000–1202 x 18–32 subtylostyles 292–339 x 9–16 absent anisochelae 1, 69–96 anisochelae 2, 17–31 9–14 absent Shakleton Fracture Zone, Antarctica, bathyal...Continued on the next page
38 x 5 Axis and filaments with longitudinal and perpendicular tracts, respectively, of mycalostyles and subtylostyles, acanthotylostrong yles and desmas in basal holdfast mycalostyles 472–1180 x 5–28 subtylostyles 205–523 x 3–15 smaller curved subtylostyles 60–95 x 5–8 undifferentiated monocrepid desmas 369–657 x 25–50 acanthotylostrongyles 78–128 x 3–5 arcuate anisochelae 38–63 anchorate- unguiferate anisochelae 13–18 15–23 absent Campos Basin and Florianopo lis, Brazil, mesophotic...Continued on the next page
subtylostyles 1, 637-(811)-933 x 15.9-(20.4)-28.7 subtylostyles 2, 356-(494)-719 x 6.5-(10.3)-14.3 subtylostyles 3, 223-(250)-299 x 3.8-(4.8)-7.0 undifferentiated undifferentiated palmate anisochelae 13.8-(15.4)- 17.2 absent contorted sigmas 39.5-(46.7)- 54.1 SW Indian Ocean Ridge, S Africa, mesophotic...Continued on the next page
194–280 x 130 Axis of branches and stem with bundles of smaller mycalostyles, filaments with bundles of larger mycalostyles, large curved styles in basal cone mycalostyles 705-(751)-797 x 23-(25.5)-27 mycalostyles 627-(687)-756 x 15-(17.5)-20 curved mycalostyles 382-(462.1)-540 x 32-(39.97)-48 Microacantho- tylostrongyle 87-(98.1)-109 x 1.3-(1.7)-2.1 palmate absent anisochelae 11-(11.8)-12.5 sigmas 21-(22.9)-24 Davidson Seamount and Monteray Canyon, California, bathyal...Continued on the next page
85 x 1.5 Axis with core of longitudinal mycalostyles, projecting filaments cored by subtylostyle bundles, desmas present in basal part the sponge mycalostyles 570-(772)- 893 x 12.9- (20.6)-28.3 subtylostyles 1, 470-(584)-719 x 9.7-(13.5)-19.7 subtylostyles 2, 133-(176)-218 x 3.1-(5.5)-7.0 subtylostyles 3, 113-(321)-557 x 18.6-(25.8)-31.8 desmas 186-(318)-445 arcuate 15.2-18.9- anisochelae 22.6 1, 82.2-(95.2)- 107.6 arcuate anisochelae 2, 9.5-(11.9)- 14.1 absent Southwest ern Indian Ocean Ridge, mesophotic- bathyal...Continued on the next page
5–15 x 0.7 Axis of stem with longitudinal bundles of mycalostyles, filaments of subtylostyles perpendicular to stem, no special basal spicules mycalostyles subtylostyles 351-(567)- 224-(265)-292 742 x 4.1-(7.1)-13.4 x 13.3-(19.8)- 32.5 undifferentiated arcuate anisochelae 15.2-(19.7)- 26.9 palmate anisochelae 6.9-(10)- 11.3 11.9-15.7- 20 absent Southwest ern Indian Ocean Ridge, mesophoticbathyal...Continued on the next page
mycalostyles 581-(731)-918 x 16.0-(23.8)- 34.2 subtylostyles unknown 514-(638)-810 x 11.0-(15.8)-20.3 acanthotylostyles 75-(111)-142 arcuate anisochelae 42.7-(49.3)- 57.2 palmate anisochelae 8.6-(10.6)-12.6 20.3-(23.0)- 31.6 absent NW Atlantic, mesophotic- bathyal...Continued on the next page
12–16 x 1–1.6 Axis and filaments with longitudinal and perpendicular tracts of mycalostyles, respectively, acanthotylostrongyles form basal holdfast mycalostyles 236–944 x 5–15 undifferentiated Acanthotylo- strongyles 38–118 x 3–5 Palmate anisochelae 8–15 20–45 absent Campos Basin, SE Brazil, mesophotic...Continued on the next page
oxeas 216-(424.6)-77 x 5-(10.0)-20 styles/mycalostyles 420-(552.4)-70 x 8 8-(18.0)-30 mycalostyles/ subtylo styles 185-(314.3)-585 x 5-(9.4)-13 styles/oxeas/ anisostrongyles 125-(256.8)-510 x 13-(19.5)-28 palmate isochelae 23-(31.3)- 43 palmate anisochelae 10-(10.7)- 13 18-(21.9)- 25 microstrongyles 30-(51.3)-75 x 5-(7.3)-8 microtylostyles 23-(26.3)-30 x 8 Diego Ramírez Archipela go (south Chile), bathyal...Continued on the next page
15 x 1–2 Axis of stem with larger mycalostyles with micro-strongyles, filaments corerd by single smaller style, base with mass of styles, microstrongyles and microtylostrongyles mycalostyles 562–678 x 15–30 mycalostyles 208–265 x 5–10 mycalostyles 209–606 x 20–39 strongyles 37–53 x 5–12 anthomicrotylostrong yles 22–32 x 3–8 arcuate anisochelae 32–43 palmate anisochelae 8–11 Drake Passage, Sars Seamount, bathyal...Continued on the next page
styles 470–500 x 11 oxeas 425–525 x 15 sybtylote-polytylote styles 290–310 x 4–6 desmas 435–630 x 15–20 palmate absent anisochelae 11 microsubtylostyles 11–12 x 5 microstrongyles 23–95 x 1–3 Canary Islands, NE Atlantic, bathyalMegascleres: Styles of two types in two statistically significant size classes in length and width (P<0.0001). Large mycalostyles, thickest at the middle of the spicule and tapering at both ends (855-(1000)-1130 μm x 15.7- (21.2)-28.3 μm, n=47). Smaller subtylostyles with slightly swollen bases and tapering to fine points (427-(586)-805 x 3.7-(9.4)-15.3 μm, n=57).
Microscleres: Arcuate anisochelae, head with the lateral alae fully fused to the shaft and a large frontal alae significantly detached from lateral alae, foot with two fully fused nearly atrophied lateral alae and a single larger frontal ala with a tooth-like termination (Length 10.5-(13.1)-16.1 μm, large frontal alae width 2.3-(3.3)-4.2 μm, small lat- eral alae width 2.2-(2.8)-3.7 μm, n=62). Sigmas, predominantly s-shaped, fewer c-shaped, in two size classes: larger sigmas (43.4-(54.0)-68.7 μm, n=40), smaller sigmas (20.2-(27.7)-37.8 μm, n=71).
Molecular data: The 28S sequence of QM G337488 is provided in the Sponge Barcoding Database under accession number SBD#2311 and the molecular difference to other congenerics displayed in Figure 3.
Remarks: This species differs from other known species of Asbestopluma in having two sizes of sigmas and only one type of small anisochelae ( Table 4). Asbestopluma (A.) maxisigma sp. nov. appears to be most closely related to A. (A.) biserialis ( Ridley & Dendy, 1886), known from the South Pacific (SE Pacific, Ridley & Dendy 1886; Kermadec Trench, Lévi 1964; and the Coral Sea off New Caledonia, Lévi 1993), and the North Pacific (south of the Aleutian Islands, Koltun 1970), from bathyal and abyssal depths. Both species have vaguely similar pinnate pedunculate morphologies but the new species has twice as many columns of filaments (i.e. four as opposed to two). Mycalostyles-styles of the axial skeleton are much shorter and thinner in the new species, which also possesses two size classes of sigmas, but it lacks the acanthotylostrongyles found in A. (A.) biserialis.
The smaller anisochelae of A. (A.) desmophora Kelly & Vacelet, 2011, from the mesophotic-bathyal depths of the Macquarie Ridge seamounts, are similar in geometry and size to those of the present species, both having a tooth-like termination on the frontal ala of the foot, but the former also has a second category of larger anisochelae with a different geometry, has only one size category of small sigmas, and also possesses sigmancistras. The pedunculate gross morphology of A. (A.) maxisigma sp. nov. is also very different from the arborescent A. (A.) desmophora, the latter also having basal desmas and microtylostrongyles.
In its gross morphology this new species also resembles A. (A.) belgicae ( Topsent, 1901), (qv Lopes et al. 2011, Hestetun et al. 2015, Goodwin et al. 2017). However, A. (A.) maxisigma sp. nov. has the following differences: much larger styles, two size categories of styles, larger anisochelae and two categories of sigmas. Asbestopluma (A.) sarsensis Goodwin et al., 2017 is similar in spiculation to A. (A.) belgicae, and also differs from the present species for the same reasons given above, in addition to also having a very different growth form.
Asbestopluma (Asbestopluma) obae Koltun, 1964 from Wilkes Land, Antarctica differs from the present species in having acanthotylostrongyles, lacking the larger sigmas, and lacking horizontal filaments.