Poecillastra ducitriaena Kelly & Cárdenas, 2019

Kelly, Michelle, Cárdenas, Paco, Rush, Nicola, Sim-Smith, Carina, Macpherson, Diana, Page, Mike & Bell, Lori J., 2019, Molecular study supports the position of the New Zealand endemic genus Lamellomorpha in the family Vulcanellidae (Porifera, Demospongiae, Tetractinellida), with the description of three new species, European Journal of Taxonomy 506, pp. 1-25 : 15-17

Poecillastra ducitriaena Kelly & Cárdenas sp. nov.

urn:lsid:zoobank.org:act:E3C570FA-832A-4FDB-97D3-5CDA250A3797

Figs 1 , 4 , 6

Etymology

Named for the possession of triaenes in addition to the apparent spiculation of Lamellomorpha, and their guide to the phylogenetic origins of this species (‘ duci -’ in the sense of a guide).

Type material

Holotype

NEW ZEALAND • Subantarctic region of New Zealand , east of Snares Island Platform, NIWA Station TRIP3072 /8; 48.5° S, 168.0° E; depth 125–213 m; 21 Oct. 2010; NIWA 61944 leg.; fish bottom trawl; UPSZTY 178604 (a small piece of the holotype preserved in 70% ethanol, as well as a spicule preparation), NIWA.

Type locality

Subantarctic region of New Zealand, Snares Island Platform, depth 125– 213 m.

Description

Multilamellate, foliose, fan sponge ( Fig. 4A ), 160 mm high, 104 mm wide, with a short thick stalk about 2 cm thick. Lamella up to 2 cm thick in places, attenuating to curled margins. Oscules were not visible on the holotype. Cribriporal pore areas are widespread between parallel tangential tracts of oxeas; individual pores 80–160 µm in diameter, on both sides of the lamella. Texture firm, compressible, flexible, granular and smooth to the touch. Colour in preservative tan.

Skeleton

Choanosome composed of huge swathes of long straight oxeas, radiating through the lamella, terminating below the surface ( Fig. 6E ). Contort oxeas are found in the stalk. Ectosome, relatively thick, packed with microxeas and perforated by ostia.

Spicules

MEGASCLERES ( Fig. 4 B–C)

Oxeas with long fine attenuated tips, 1725(1150‾2271) × 16(8‾22) µm; contort oxeas in the stalk, 1801(1095‾2671) × 13(5‾17) µm; short-shafted triaenes, relatively uncommon, rhabd straight, attenuating, 290(260‾300) µm, clads curved or acutely bent, occasionally with bifurcating tips, 232(200‾250) µm, cladome width 400‾500 µm long.

MICROSCLERES ( Fig. 4 D–F)

Microxeas, heavily microspined, sometimes faintly centrotylote and acutely centrally bent, sharp ended, abundant, 38(28‾46) × 3(2‾4) µm; metaster- to amphiaster-like streptasters with long, microspined rays, rare, 8(5‾12) µm long; spirasters with dense, short rays, rare, 5‾7 µm long.

Distribution

East of Snares Island Platform.

Substrate, depth range and ecology

Attached by a thick stalk to sediment covered rocky substrate, depth 125‾ 213 m.

DNA barcodes

COI. Holotype ( MK033626 ); 28 bp difference with the COI of L. strongylata ; 24 bp difference with the COI of Poecillastra compressa (Bowerbank, 1866) ( HM592675 ). 28S (C1-C2). Holotype ( MK 033144 ); 5 bp difference with the 28S (C1-C2) of L. strongylata ; 3 bp difference with the 28S (C1-C2) of Poecillastra compressa ( HM592757 ).

Remarks

This remarkable sponge was first identified as a third species of Lamellomorpha, as it appeared to have an almost identical form (stalked, multilamellar fan), a megasclere complement of straight and contort oxeas (more or less restricted to the stalk), small centrotylote microxeas, and metasters (albeit rare). Because the short-shafted triaenes were relatively uncommon, it was initially hypothesised that this was a species of Lamellomorpha with rudimentary triaenes that ‘showed the way’ to the true affinity of the genus with other triaene-bearing Tetractinellida . However, molecular sequencing consistently linked Poecillastra ducitriaena sp. nov. with other Poecillastra species ( Fig. 7 ). Despite its consistency with two independent markers, we note that this grouping is not supported (bootstrap of 60 for COI, of 10 with 28S). This may be due to the absence of other subantarctic Poecillastra species in our sampling which Poecillastra ducitriaena sp. nov. may be closer to (P. Cárdenas, unpublished results).

Although not fully documented ( Kelly et al. 2009), our knowledge of Poecillastra in the New Zealand region is reasonable and includes what we consider to be Poecillastra laminaris (Sollas, 1886) (Zeng et al. 2016) and Poecillastra schulzei (Sollas, 1886) . While several undescribed species are known from the New Zealand EEZ, no specimens are known that contain the characteristic contort oxeas of Poecillastra ducitriaena sp. nov.

Figures

Fig. 1. Study area showing the collection localities for: Lamellomorpha strongylata Bergquist, 1968, around Middlesex Bank, Three Kings Islands, and Spirits Bay (triangles); L. australis Kelly & Cárdenas sp. nov., Bounty Platform, Campbell Plateau, Solander Trough, and Macquarie Ridge (Australian EEZ) (circles); Poecillastra ducitriaena Kelly & Cárdenas sp. nov., on the eastern edge of the Snares Platform (square); and Poecillastra macquariensis Kelly & Cárdenas sp. nov., on Seamount 5, Macquarie Ridge (star).

Fig. 4. Morphology, megascleres and microscleres of Poecillastra ducitriaena Kelly & Cárdenas sp. nov. (NIWA 61944 leg., holotype). A. Preserved holotype showing stalked morphology (both sides). B. Shortshafted triaenes with curved clads and short rhabd. C. Sinuous and straight oxeas. D. Microspined microxeas, sometimes faintly centrotylote, sharp ended. E. Metaster- to amphiaster-like streptasters with long, microspined rays. F. Spirasters with dense, short rays.

Fig. 6. Skeletal arrangement. A. Lamellomorpha australis Kelly & Cárdenas sp. nov. showing dense, crustose ectosome packed with microrhabds and other microscleres, a rough megasclere bundle in the subectosome, emerging perpendicular to the surface, and the choanosome densely packed with microscleres (NIWA 89736 leg., holotype). B. L. australis sp. nov. showing the subectosome densely packed with microscleres, and megascleres radiating in the plane of the sponge body (NIWA 89717 leg.). C. L. strongylata Bergquist, 1968 showing a thin, fleshy ectosome packed with microrhabds and other microscleres, through which projects an ‘extra-axial’ tract of megascleres, traversing the subectosome and projecting through the surface (NIWA 93474 leg.). D. L. strongylata showing the ‘axial’ arrangement of contort strongyloxeas in the deep choanosome (NIWA 93474 leg.). E. Poecillastra ducitriaenea Kelly & Cárdenas sp. nov. showing a densely packed, crustose ectosome through which subectosomal megascleres project, a relatively cavernous subectosomal region packed with microxeas, and in the deep choanosome, huge swathes of oxeas (NIWA 61944 leg., holotype). Scale bars = 500 µm.

Fig. 7. Astrophorina COI and 28S maximum likelihood (ML) trees reconstructed with RAxML under the generalized time-reversible Gamma (GTRGAMMA) model. ML bootstrap supports (100 bootstrap replicates). GenBank accession numbers are given after each taxon name. In green are the new sequences produced during this study.