Chondrocladia (Chondrocladia) zygainadentonis, 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 : 120-123

Chondrocladia (Chondrocladia) zygainadentonis sp. nov.

Figures 24 & 25 , Table 10

urn:lsid:zoobank.org:act:BE9789AD-04EA-4A90-8374-2B669796A19E

Material examined: Holotype: QM G337557 , off Gladstone , Coral Sea, Queensland, Australia, Station 128, 23° 37’ 52.3”– 23° 39’ 32.4” S, 154° 39’ 34.9”– 154° 38’ 37.7” E, 1770– 1761 m, Beam Trawl, Coll. Merrick Ekins on RV Investigator, Cruise IN2017_ V03 , Sample 128-111, 13/vi/2017.

Etymology: Gr. zygaina, f. a kind of shark; L. dentionis, f. teething

Distribution: This species is presently known only from the Coral Sea, off the Northeast coast of Queensland, at bathyal depth.

Description:

Growth form: An erect delicate single-axis arbuscular sponge resembling a ‘Bottlebrush’ consisting of a cylindrical stem with four columns of filaments ( Figure 24 J ). The stem is 23 mm long and only 0.5 mm wide. The filaments are up to 2.5 mm long and less than 200 µm wide. No basal attachment was collected.

Colour: Ivory in ethanol.

Ectosomal skeleton: The ectosomal skeleton consists of a thin membrane containing chelae and sigmancistras ( Figure 25 A–D).

Endosomal skeleton: The endosomal skeleton consists of bundles of mycalostyles longitudinally arranged in the axis of the stem. The stem also contains the subtylostyles and rare thin styles ( Figure 25 A–B).The filaments consist of longitudinally arranged subtylostyles, with radial arrangement for support against the stem ( Figure 25 B, D ).

Megascleres: Larger mycalostyles with tapering ends and a blunt point (1030-(1261)- 1440 x 18.0-(23.9)- 34.7 µm, n=54) ( Figure 24 D–E). Subtylostyles with slightly swollen bases and tapering points (502-(594)-652 x 8.3- (12.5)- 15.6 µm, n=55) ( Figure 24 F–G). Rare very thin styles that only occur in the stem (204-(473)- 1160 x 2.4- (3.8)-6.0 µm, n=5) ( Figure 24 H–I).

Microscleres: Uncommon large unguiferate anchorate chelae usually with unequal number of alae on opposing ends, with long sharp alae ranging in number from 2 to 6 per end (44.7-(7.9)-73.3 x 4.3-(6.3)- 8.6 µm, n=53) ( Figure 24 A ). More common smaller tridentate unguiferate isochelae with equal sized alae (25.9-(34.5)-39.0 x 2.7-(3.4)- 4.4 µm, n=61) ( Figure 24 B ). Rare sigmancistras with almost 90 o torsion (24.8-(27.7)-29.2 x 1.5-(2.1)-2.8 μm, n=9) ( Figure 24 C ).

Molecular data: It was not possible to get unambiguous molecular data from the type material

Remarks: This new species is unusual amongst Chondrocladia (Chondrocladia) in having an arbuscular morphology resembling the flower of the ‘Bottlebrush’ plant ( Callistemon spp .), and the long sharp-toothed larger chelae having an asymmetrical numbers of alae on each end. Only two other species appear to have spicules resembling these large-toothed chelae: Ch. (Ch.) levii Cristobo et al., 2005 and Ch. (Ch.) cf. guiteli Topsent, 1904 (sensu Cristobo et al. 2005). However, both of these abyssal Atlantic species have very different gross morphologies, as well as spicule categories and spicule dimensions ( Table 10 ).

Figures

FIGURE 24. Chondrocladia (Chondrocladia) zygainadentonis sp. nov., holotype QM G337557. A. Larger unguiferate anchorate isochelae with long sharp alae and an uneven number of alae on the upper and lower ‘jaws’. B. Smaller tridentate unguiferate anchorate isochelae. C. Sigmancistra. D. Larger mycalostyle. E. Magnified ends of the mycalostyle illustrated in D. F. Subtylostyle. G. Magnified ends of the subtylostyle illustrated in F. H. Thin styles. I. Magnified ends of the style illustrated in H. J. Fixed holotype QM G337557.

FIGURE 25. Chondrocladia (Chondrocladia) zygainadentonis sp. nov. A. Stem of the holotype showing the filaments branching at right angles. B. Close up of the branching of the filament off the stem, showing all three large spicules in the endosome and the chelae in the ectosome. C. Filament exterior with chelae in the ectosome. D. Filament endosome exposed showing the subtylostyles longitudinally arranged, below the chelae encrusting ectosome.