Belinda Alvarez

Phylogenetic relationships of the family Axinellidae (Porifera: Demospongiae) using morphological and molecular data

Alvarez, B., Crisp, M.D., Driver, F., Hooper, J.N.A. & Van Soest, R.W.M. (2000). Phylogenetic relationships of the family Axinellidae (Porifera: Demospongiae) using morphological and molecular data. —Zoologica Scripta, 29, 169–198.

The systematics of Raspailiidae (Demospongiae: Poecilosclerida: Microcionina) re-analysed with a ribosomal marker

We present a 28S rDNA gene tree of selected Raspailiidae, Axinellidae and other demosponges to obtain insight into raspailiid phylogeny and character evolution. The Raspailiidae in our data set cluster in a well-supported clade, distinguished from Axinellidae, Agelasida and Hadromerida. Raspailia (s.s.), Eurypon, Sollasella, Aulospongus and Ectyoplasia form a Raspailiidae clade. Some Raspailia subgenera, in particular R. (Parasyringella), are not retrieved monophyletically. Trikentrion falls into the Thrinacophorinae, and not the Cyamoninae as earlier hypothesized. The axinellid genera Ptilocaulis and Reniochalina also cluster with Raspailiidae, distant from the other Axinellidae. The suitability of particular morphological characters for raspailiid phylogeny is discussed.

Analysis of intragenomic variation of the rDNA internal transcribed spacers (ITS) in Halichondrida (Porifera: Demospongiae)

Three species of sponges, Axinella aruensis, Phakellia sp. and Acanthella cavernosa, were selected to investigate the extent of intragenomic variation (IGV) in the internal transcribed spacers (ITS-1 and ITS-2) of the ribosomal DNA within the order Halichondrida. The IGV was detected in both the spacers and in the three species. At least three non-identical sequences were found in any single individual with the number of polymorphic sites within species ranging from 6 to 77. Uncorrected distance values up to 29% were observed in the ITS-2 of Axinella aruensis. The levels of polymorphism found in this species are the highest reported for Porifera and comparable to those observed in hybrid species of scleractinean corals. Analyses of ITS sequences from multiple clones from individuals of Halichondrida are strongly recommended if these genetic markers are to be used to depict phylogenetic and/or phylogeographic relationships of closely related species and their populations. Data from other nuclear and mitochondrial markers should be used to complement conclusions derived from studies based on ITS sequences.

The phylogeny of halichondrid demosponges: past and present re-visited with DNA-barcoding data

Halichondrid sponges play a pivotal role in the classification of demosponges as changes in their classification has had direct consequences for the classification of Demospongiae. Historically, the systematics of halichondrids has been unstable. During the 1950s, the order was divided into two subclasses, which were based on empirical and assumed reproductive data. Subsequent morphological and biochemical analyses postulated the re-merging of halichondrid families, but recent molecular data indicate their polyphyly. Here we review the classification history of halichondrid taxa, compare it with the current and predominantly ribosomal molecular data, and support the new phylogenetic hypotheses with mitochondrial data from DNA barcoding.

Sponge biodiversity and ecology of the Van Diemen Rise and eastern Joseph Bonaparte Gulf, northern Australia

Australia is increasingly recognised as a global hotspot for sponge biodiversity, but there is a knowledge gap about sponge communities in northern Australia, including those in Commonwealth Marine Reserves. We aim to quantify sponge biodiversity of the eastern Joseph Bonaparte Gulf and adjacent Van Diemen Rise (VDR) and to examine spatial and environmental patterns in community structure. Sponges were collected with a benthic sled from 65 sites encompassing five geomorphic features (bank, terrace, ridge, plain, and valley), study area (as a proxy for distance offshore) and three environmental variables (depth, substrate hardness, and slope). A total of 283 species were collected, representing four classes, 53 families and at least 117 genera. Sponge richness and biomass were related to those of other taxa. Sponge diversity was generally highest further offshore and on raised geomorphic features, particularly banks. Sponge assemblages on the same bank were more similar than those from different banks, although full interpretation of patterns is limited by the relatively low sampling effort. The current study will help facilitate integrated marine management by providing a baseline species inventory, supporting the VDR’s carbonate banks as a key ecological feature, and highlighting the importance of sponges as habitat providers and potential biological surrogates for monitoring.

Family Dictyonellidae Van Soest, Diaz & Pomponi, 1990

Dictyonellidae Van Soest et al. (Demospongiae, Halichondrida) are sponges with fleshy appearance, lacking a special surface skeleton of spicules. The spicular density is often relatively low and skeletons consist of ill-defined bundles following a dendritic pattern or making an irregular reticulation. Spongin may be important as binding substance. Spicules comprise usually long, often somewhat flexuous styles, occasionally strongyles, oxeas or oxeote derivations, but shorter straight styles are not uncommon. Characteristically, spicule endings are variable and often telescoped. Dictyonellidae are cosmopolitan in occurrence, but are more common in warmer waters. Compared with the original contents, the family has been here extended to include Phakettia,Stylissa and Svenzea,and now comprises ten valid genera (out of 17 nominal genera).

Taxonomic revision of the genus Latrunculia Du Bocage (Porifera: Demospongiae: Latrunculiidae) in New Zealand

Abstract The genus Latrunculia in New Zealand was believed to be represented by at least three species: L. brevis Ridley & Dendy and two undescribed species. However, results from recent studies indicate that the genus contained a complex of at least eight genetically distinct species. In this paper we revise the taxonomy of Latrunculia in New Zealand and describe nine new species. Eight of these were previously identified using genetic techniques (i.e., L. kaakaariki sp. nov., L. duckworthi sp. nov., L. procumbens sp. nov., L. wellingtonensis sp. nov., L. kaikoura sp. nov., L. triverticillata sp. nov., L. fiordensis sp. nov., and L. millerae sp. nov.) and one (L. oxydiscorhabda sp. nov.) was distinguished based only on morphological differences. The species described fall into two morphological groups, spinispiraefera and triverticillata, which can be diagnosed by the number of whorls present along the discorhabd axis. The status of L. brevis, and other subantarctic species (i.e., Latrunculia bocagei, L. antarctica, L. lendenfeldi, L. spinispiraefera) is discussed; all of these species are considered to be valid but not conspecific with any of the species described here.

Implications of Sponge Biodiversity Patterns for the Management of a Marine Reserve in Northern Australia

Marine reserves are becoming progressively more important as anthropogenic impacts continue to increase, but we have little baseline information for most marine environments. In this study, we focus on the Oceanic Shoals Commonwealth Marine Reserve (CMR) in northern Australia, particularly the carbonate banks and terraces of the Sahul Shelf and Van Diemen Rise which have been designated a Key Ecological Feature (KEF). We use a species-level inventory compiled from three marine surveys to the CMR to address several questions relevant to marine management: 1) Are carbonate banks and other raised geomorphic features associated with biodiversity hotspots? 2) Can environmental (depth, substrate hardness, slope) or biogeographic (east vs west) variables help explain local and regional differences in community structure? 3) Do sponge communities differ among individual raised geomorphic features? Approximately 750 sponge specimens were collected in the Oceanic Shoals CMR and assigned to 348 species, of which only 18% included taxonomically described species. Between eastern and western areas of the CMR, there was no difference between sponge species richness or assemblages on raised geomorphic features. Among individual raised geomorphic features, sponge assemblages were significantly different, but species richness was not. Species richness showed no linear relationships with measured environmental factors, but sponge assemblages were weakly associated with several environmental variables including mean depth and mean backscatter (east and west) and mean slope (east only). These patterns of sponge diversity are applied to support the future management and monitoring of this region, particularly noting the importance of spatial scale in biodiversity assessments and associated management strategies.

Family Bubaridae Topsent, 1894

Bubaridae Topsent (Demospongiae, Halichondrida) is used here in the restricted sense of Topsent (1928c) to group exclusively encrusting forms that were related to the family Axinellidae at one time or another. The family includes four valid genera and approximately 30 species, characterised by a basal layer of interlacing spicules, generally diactines, and erect monactines spicules, with bases embedded in the basal layer, projecting perpendicularly to the substratum. Most species of the family are found in deep waters down to 1300 m but shallow water species are also known.