Cladorhiza australis, Ekins & Erpenbeck & Hooper, 2020

Ekins, Merrick, Erpenbeck, Dirk & Hooper, John N. A., 2020, Carnivorous sponges from the Australian Bathyal and Abyssal zones collected during the RV Investigator 2017 Expedition, Zootaxa 4774 (1), pp. 1-159 : 47-72

Cladorhiza australis sp. nov.

Figures 7 & 8 , Tables 5 & 6

urn:lsid:zoobank.org:act:5C924F06-535C-418A-9328-F418F21ADB98

Material examined: Holotype: QM G337456 off Freycinet Peninsula , Station 6, Tasmania, Australia, 41° 37’ 32.0”– 41° 41’ 21.2” S 149° 33’ 5.4”– 149° 35’ 3.5” E, 4022–4052 m, Beam Trawl, Coll. Merrick Ekins on RV Investigator, Cruise IN2017_ V03 , Samples 6-158, 6-162.1 18/v/2017.

Paratype: QM G337474 off Newcastle , Station 65, New South Wales, Australia, 33° 26’ 27.6”– 33° 26’ 6”S, 152° 42’ 7.2”– 152° 39’ 54” E, 4280– 4173 m, Beam Trawl, Coll. Merrick Ekins on RV Investigator, Cruise IN2017_ V03 , Sample 65-122.2, 30/v/2017 .

Etymology: This species is named for its southern distribution.

Distribution: This species is presently known only from the abyssal zone off Tasmania and New South Wales, East Coast of Australia, at abyssal depth.

Description:

Growth form: An erect, unbranched, pedunculate ‘crinorhizoid’, parasol-shaped sponge with filaments extending outwards, almost horizontally from the body ( Figure 7 K ). The filaments in the holotype (G337456) are 13 mm long and 0.3 mm wide. The body of the sponge is a double cone, 8 mm in diameter across the centre. The stem of the sponge is 100 mm long, but is broken. The stem is flattened and 1 x 2 mm thick and terminates in basal roots. The body of the sponge is disc-shaped with a central papillate apex. The paratype (G337474) is identical to the holotype except that it is smaller, in poorer condition, with the body 9.54 mm in diameter across the base of the cone, and the remaining bases of the filaments are only 3 mm in length.

Colour: A tan coloured body with off white filaments and stem

Ectosomal skeleton: The ectosomal skeleton, on the body and the filaments is covered on the external surface with tridentate ‘unguiferate’ anisochelae ( Figure 8 D ). The ‘cleistochelate’ anisochelae are uncommonly distributed in the sub-surface region of the ectosome supported by the medium sized mycalostyles. On the stem however, the outer layer of the membranous ectosome is covered by a uniform carpet of ‘cleistochelate’ anisochelae ( Figure 8 A,B ) and this is also supported by the medium sized mycalostyles forming a protective sheath of the endosome ( Figure 8 C ).

Endosomal skeleton: The endosomal skeleton of the body, the filaments, the stem and the roots consisting mainly of the larger mycalostyles in concentrated longitudinal bundles ( Figure 8 C ), but also includes the rarer medium and small mycalostyles. The large mycalostyles originate in the centre of the body and radiate out to become the horizontal filaments.

Megascleres: The megascleres consist of three different forms of mycalostyles varying in their terminations, but all having a larger diameter in the centre of the spicule than at the ends. The largest mycalostyles have blunt ends, occasionally sinuous and oxeote in shape. The medium-sized and smaller, thin, supporting mycalostyles both have sharp tips.

Dimensions are given in Table 6

Microscleres: The microscleres consist of abundant small anchorate ‘unguiferate’anisochelae with three large alae and three smaller alae on each end, and less common larger multidentate anchorate anisochelae with upper alae overlapping lower alae (i.e. reminiscent of the ‘cleistochelate’ condition). These ‘cleistochelate’ anisochelae mostly have three upper alae, sometimes four, and three curved lower alae. Sigmas are rare, slightly contort, and consist of a single size class ( Table 6 ).

Molecular data: The 28S sequence of QM G337456 is provided in the Sponge Barcoding Database under accession number SBD#2314 and the molecular difference to other congenerics displayed in Figure 3 .

Remarks: In addition to the ‘unguiferate’ anchorate anisochelae common to many other species of Cladorhiza , C. australis sp. nov. has a second unique form of anisochelae that verges on the ‘cleistochelate’ morphology which is not present in any of the other species (see Table 5 ). Lopes et al. (2011) proposed that similar to the chelae transformation series in myxillids (arcuate-anchorate-birotulate) ( Hajdu et al. 1994), cladorhizids also appear to have a transformation series from arcuate isochelae-cleistochelae-abyssochelae. It is possible, therefore, that this ‘cleistochelate’ anchorate anisochelae condition, as demonstrated in C. australis sp. nov., is similar through the progressive expansion of alae longitudinally until they touch or nearly touch each other ( Lopes et al. 2011).

Of the 44 known species of Cladorhiza only seven have ‘parasol’ growth form (dubbed the ‘crinorhiza’ morphological group of cladorhizids by Ridley & Dendy 1886): C. mirabilis ( Ridley & Dendy, 1886) , C. longipinna In addition to the unique anisochelae character described above, C. austalis sp. nov. differs from these in a combination of other characters (see Table 5 ). Cladorhiza australis sp. nov. differs from C. mirabilis , C. hubbsi , C. mexicana and C. poritea sp. nov. in lacking pseudoamphiasters. It differs from C. longipinna in its spicule sizes, in particular having smaller unguiferate anisochelae, larger mycalostyles in three size classes, and the possession of sigmas. Cladorhiza similis also has three size classes of mycalostyles but each with a smaller size range than those of C. australis sp. nov., and it also lacks sigmas. Cladorhiza corona has mycalostyles of approximately the same size range as C. australis sp. nov. distributed throughout all parts of the skeleton except in the ectosome, but has in addition (sub)tylostyles and sigmancistras in the ‘crown’ (a structure that is apical to body and surrounded by the filaments), and short anisoxeas in the basal disc (which was not collected in our species). Similarly, C. kensmithi (also a parasol-shaped growth form with a ‘crown’), has three size classes of mycalostyles of more-or-less the same size range as those of C. australis sp. nov., sigmancistras, and strongyles in its basal rhizoid holdfast. Finally, C. australis sp. nov. differs from C. poritea sp. nov. in lacking pseudamphiasters, but having sigmas in addition to unguiferate anisochelae as microscleres.

Ridley & Dendy, 1886, C. similis ( Ridley & Dendy, 1886) , C. corona ( Lehnert et al., 2005) , C. hubbsi Lundsten et al., 2017 , C. kensmithi Lundsten et al., 2017 and C. mexicana Lundsten et al., 2017 . With the addition of the two new species described in the present work, C. australis sp. nov. and C. poritea sp. nov., the number of parasol-species increases to nine.

Figures

FIGURE 3. Maximum-likelihood phylogram of the DNA sequences of this study in comparison with other, published cornivorous sponges. Sequences from taxa of this study are in bold. Number at the branches are RAxML rapid bootstrap values. Numbers following the taxa are either QM registration numbers (QM G3xxxxx) or NCBI Genbank accession numbers. Scale bare are substitutions per site. Please note that the reconstruction does not represent a phylogeny as due to the variability of the 28SrRNA gene C-Region barcoding marker no unambiguous alignment is possible and clipping ambiguous sites would remove diagnostic characters for taxon distinction. The tree therefore indicates molecular differences rather than a robust phylogeny.

FIGURE 7. Cladorhiza australis nov. sp. Holotype QM G337456. A. Larger multidentate (3–4 upper alae) ‘cleistochelate’ anisochelae. B. ‘Cleistochelate’ anisochelae showing four upper alae. C. Smaller tridentate ‘unguiferate’ anisochelae. D. Sigma. E. Large mycalostyle. F. Magnified ends of the mycalostyle illustrated in E. G. Medium-sized mycalostyle. H. Magnified ends of the mycalostyle illustrated in G. I. Small mycalostyle. J. Magnified ends of the small mycalostyle illustrated in I. K. preserved holotype. L. preserved roots of the holotype.

FIGURE 8. Cladorhiza australis nov. sp. Holotype QM G337456.A. Stem of the sponge, showing the carpet of ‘cleistochelate’ anisochelae, and where they have been abraded off the underlying sheath of the ectosome. B. Close-up of the ‘cleistochelate’ anisochelae in A. C. Stem of the sponge with the ectosome peeled off the underlying mycalostyle bundle of the endosome. Note the mycalostyle contained in the ectosome. D. Two filaments, the uppermost filament has part of the ectosomal layer containing the ‘unguiferate’ anisochelae removed showing the mycalostyles in the endosome.

Tables

TABLE 5. Comparative morphological and distributional data for all known species of Cladorhiza.

Species	Source	Morphology	Total height x stem width (mm)	Skeleton	Spicules of main axis (LxW μm)	Spicules of lateral filaments or body (LxW μm)	Spicules of basal attachment (LxW μm)	Chelae (L μm)	Sigmancistras (L μm)	Sigmas (L μm) and other microscleres	Locality/ depth range
Cladorhiza australis sp. nov.	present study	Pedunculate erect, unbranched, ‘crinorhizoid’ parasol- shaped sponge with filaments nearly horizontal to the discshaped body, long thin stem, basal attachment missing	75 x 2	Axis of stem and body cored by longitudinal bundles of mycalostyles of 3 size/ shape classes	mycalostyles 1, 1380–4960 x 21–85 mycalostyles 2, 1000–1940 x 15–30 mycalostyles 3, 485–1080 x 15–30	undifferentiated	undifferentiated unguiferate anisochelae 24–35 x 2–5 cleistochelate anisochelae 35–44 x 18–32		absent	sigmas 43–100 x 2–5	E. Australia, off Tasmania and New South Wales, abyssal
Cladorhiza moniqueae sp. nov.	present study	Pedunculate erect, unbranched, with body a horizontally aligned teardrop- shaped cushion, 6 medusoid-like tentacular filaments, on short (broken) stem, basal attachment missing	15 x 7	Axis of stem cored by bundles of mycalostyles extending into the cushion- shaped body where they form a thick radiating mass, eventually piercing the ectosome and hispid surface	mycalostyles 1, 777-(1321)-1760 x 18-(28)-37 mycalostyles 2, 569-(929)-1120 x 9-(14)-19	undifferentiated	unknown	tridentate unguiferate anisochelae 49-(55)-60	36-(44)-49 x sigmas 1, 1-(2)-4 165-(241)-289 x 7-(10)-15 sigmas 2, 71-(109)-166 x 2-(4)-6		E. Australia, off New South Wales, abyssal

...Continued on the next page