Theonella maricae, Hall & Ekins & Hooper, 2014

Hall, Kathryn A., Ekins, Merrick G. & Hooper, John N. A., 2014, Two new desma-less species of Theonella Gray, 1868 (Demospongiae: Astrophorida: Theonellidae), from the Great Barrier Reef, Australia, and a re-evaluation of one species assigned previously to Dercitus Gray, 1867, Zootaxa 3814 (4), pp. 451-477 : 458-461

Theonella maricae n. sp.

Figs 1 , 4–5

Material examined. Holotype: QM G331427 (=SBD513035), Australia, Great Barrier Reef , inter-reef sea floor, south-east of Guthrie Shoal , 23.095°S 151.875°E, 28.0 m (depth), coll. CSIRO Great Barrier Reef Seabed Biodiversity Project on RV Lady Basten, 22.Sep.2004, epibenthic sled.

Description. Based on examination of holotype; specimen post-fixed in ethanol (70%) after initial frozen storage.

Growth form and gross morphology: s ponge consists of very thin sheets, thickness ~ 50 µm; sheets encrust over assorted non-specific substrates, cements a variety of unidentified broken gastropod shells, diatoms, broken coral debris into single mass; incorporates large amounts of filamentous algae, quartz sand and debris; holotype in three small ovoid masses, largest mass measures ~ 2 × 2 × 1 cm (total mass dimensions) ( Figs 1B , 5A–B ).

Colour: unknown in life; pale orange to yellow portions of sponge mixed with green algae and dirty cream to brown snail shells, sand and debris when frozen; colour retained in ethanol; stains ethanol pale golden yellow; yellow pigment greasy.

Oscules: unobserved macroscopically in frozen and fixed material; also unobserved microscopically.

Texture: difficult to determine because of large amounts of debris in sponge mass; sponge soft, fragile, friable, granular, flaccid, limp, highly compressible, slowly resilient, spongy.

Surface ornamentation: even, lightly granular.

Ectosomal skeleton: indistinguishable from choanosome.

Choanosomal skeleton: lax, vague; rigid skeleton entirely absent; skeleton consists only of confused arrangement of interstitial microscleres scattered throughout mesohyl; microscleres sparse in patches, distributed singularly, concentrated in other regions, forming moderately dense carpet; collagen homogenous, slightly granular in appearance; occasional foreign spicules (oxeas, rods from ascidians) incorporated into mesohyl ( Figs 5B–C ).

Megascleres: nil.

Microscleres: single category of microrhabd; microrhabds as highly spined microxeas, robust, large, slightly curved, curvature irregular, tapering at ends, tips pointed, shaft covered with numerous, fine, short, conical spines, tips unspined; spines shorter than rhabd width, raised obviously from spicule shaft, arise perpendicular to axis; shaft straight, lacks torsion; dimensions 18.1–51.6 (37.5) × 2.2–4.4 (3.4) µm ( Fig 5D ).

Etymology. This species is named for Mary Kay Harper, College of Pharmacy, University of Utah, who is a close and extensive collaborator on the chemistry of these sponges, and whose painstaking chemical and morphometric observations on theonellids are helping to uncover suites of cryptic species. The chemical complement that Ms Harper has found in specimens of Theonella from the western Pacific may be of taxonomic importance and we honour her contribution to sponge chemotaxonomy in naming this species for her.

DNA sequence data. 1 COI barcode sequence was obtained for the holotype (GenBank Accession: KJ494356 ; see Table 1); this sequence was 709 bp in length (including primers) .

Ecology and distribution. The single specimen of T. maricae was found in the inter-reef region of the Great Barrier Reef, within the Capricorn Bunker group.

Remarks. We have, to date, found only one specimen of T. maricae in our collection. This species is difficult to isolate macroscopically, and it is likely that more specimens remain yet to be identified. Our examination of the holotype specimen shows that, like specimens of T. deliqua , large amounts of foreign sponge and non-sponge debris are incorporated into the structure of T. maricae ( Figs 5A–B ). Large amounts of filamentous algae, or possibly filamentous bacteria, can be observed within the overall mass of the holotype.

Measurements of the microrhabds of the holotype of T. maricae are in one class, with an average length of 37.5 µm and covering a range from 18.1 to 51.6 µm. This range follows a broadly normal distribution ( Fig. 4 ), although it is skewed slightly towards the larger measurements, with the most frequent length approximately reaching 48.0 µm; the 95% confidence interval for the median measurement is 35.9–40.2 µm. Detailed examination of the range of the spicules indicates that although the smallest recorded microrhabd measured 18.1 µm, the majority of the spicules is much larger, with the microrhabs typically exceeding 36 µm in length.

Comments. The description of T. maricae adds a second species which does not contain megascleres to Theonella . As with specimens of T. deliqua , the specimen of T. maricae is characterised largely by the absence of any tetractinal or monactinal structural megascleres; both species possess only microrhabds as the native spicule complement. The holotype of T. maricae is distinguished readily, however, from the specimens of T. deliqua by the size and shape of the microscleres. The microrhabds of T. maricae are typically at least twice as large as those of T. deliqua (38 µm v. 15 µm). The spines along the rhabd are small and blunt, measuring less than the width of the shaft; this is in contrast to the long and sharply pointed spines along the microrhabds of T. deliqua . The overall composition of T. maricae incorporates a variety of foreign debris and seafloor rubble, further distinguishing it from T. deliqua , which encrusts almost exclusively over the live and dead shells of a single species of Tenagodus gastropod.

Figures

FIGURE 1. Photographs of fixed whole specimens of desma-less species of Theonella Gray, 1868. A. Theonella deliqua n. sp., habitus, part of holotype (QM G329195), fixed in ethanol; scale bar = 2 cm. B. Theonella maricae n. sp., habitus, three parts of holotype (QM G331427), fixed in ethanol; scale bar = 2 cm. C. Theonella xantha (Sutcliffe, Hooper and Pitcher 2010) n. comb., habitus, part of holotype (QM G329976), fixed in ethanol; scale bar = 2 cm.

FIGURE 4. Summaries of statistics for sets of measurements of microrhabds from Theonella deliqua n. sp., Theonella maricae n. sp. and Theonella xantha (Sutcliffe, Hooper and Pitcher, 2010) n. comb. The boxes for each species include the minimum, maximum, mean, standard deviation and variance. A boxplot has been used to demonstrate the distributions of the means of the measurements for each species and to indicate significant differences among them. Outliers are indicated by asterisks (*). The ranges of the measurements for T. deliqua and T. xantha can be seen to be approximately equivalent, and are normally distributed. Stronger skew and Kurtosis are shown for the measurements for the specimens of T. maricae. Most measurements of the microrhabd length for T. maricae greatly exceed those of the other two species, as illustrated in the boxplot.

FIGURE 5. Theonella maricae n. sp. Micrographs (SEM) of holotype, QM G331427. A. Overview of a fragment of sponge, showing the incorporation of large amounts of organic and inorganic debris; scale bar = 1 mm. B. Detail view of sponge, showing thin sheets over debris, including filamentous algae, gastropod shells and other carbonates; scale bar = 500 µm. C. Detail of sheets, showing aggregation of microrhabds in an unstructured, random arrangement; scale bar = 100 µm. D. Single microrhabd; scale bar = 30 µm.