Among all present demosponges, lithistids represent a polyphyletic group with exceptionally well-preserved fossils dating back to the Cambrian. Knowledge of their recent diversity, particularly in the Tropical Western Atlantic Ocean (TWA) where they are common in deep waters, is scarce making any comparison between present and past major ‘lithistid’ faunas difficult. In addition, the lack of sufficient molecular and morphological data hamper any predictions on phylogenetic relationships or phylodiversity from this region. The Harbor Branch Oceanographic Institute (HBOI, Fort Pierce, Florida) holds the largest collection of TWA lithistid sponges worldwide, however, the majority remain to be taxonomically identified and revised.
In this study we provide sequences of 249 lithistid demosponges using two independent molecular markers (28S rDNA (C1-D2) and
This first integrative approach of TWA ‘lithistid’ demosponges contributes to a better understanding of their phylogenetic affinities, diversity and bathymetric distribution patterns within the TWA. As in the Pacific, the TWA ‘lithistid’ demosponges dominate deep-water habitats. Deeper taxonomic investigations will undoubtedly contribute to a better comparison between present major ‘lithistid’ faunas and their fossil record in the Mesozoic.
Among all present demosponges, lithistids represent a palaeontologically important polyphyletic group, with exceptionally well-preserved fossils dating back to the Cambrian (e.g.,
However, the present-day lithistid species and their phylogenetic diversity in several marine bioregions including the Western Indian Ocean, Subantarctic regions including South Africa, Northern Pacific and Tropical Western Atlantic (TWA) are incompletely understood. While ‘lithistid’ demosponges in the TWA are reported from continental shelves, caves and slopes by
Desma-bearing demosponges, historically referred to as ‘lithistid’ demosponges, form a polyphyletic group. Molecular systematics now group the majority of ‘lithistid’ demosponges (11 out of 13 families) to the order Tetractinellida
Aside from the report of ‘lithistids’ in some specific island regions of the TWA, such as Barbados (
Therefore, the aim of this study is to (1) provide a general molecular phylogenetic overview of the subordinal classification within Tetractinellida; (2) focus on desma-bearing taxa from the TWA to provide a robust phylogeny for further analyses. In order to achieve this aim we investigated a large part of the extensive HBOI ‘lithistid’ collection (249 specimens) by means of generating independent molecular markers (
Abbreviations correspond to the different locations (GULF, Gulf of Mexico; CUR, Curaçao; BON, Bonaire; StVIN, St. Vincent; MAR, Martinique; GUAD, Guadaloupe; PUE, Puerto Rico; JAM, Jamaica; HON, Honduras; TUR and CAI, Turks and Caicos; BAH, Bahamas; FLO, Florida). Arrows depict main surface currents. Map generated with GeoMapApp 3.6.3 (
Sponge samples were collected from the Tropical Western Atlantic (TWA) using the Johnson-Sea-Link manned submersibles with permission granted to Harbor Branch Oceanographic Institute by: the United States National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Dry Tortugas National Park (letters of acknowledgement F/SER25:KM, F/SER23:PE, SER02-130) and the Florida Keys National Marine Sanctuary (permit numbers 2001-049, 2001-043); the Government of the Bahamas, Department of Fisheries; the Government of Honduras, Department of Fisheries (DIGEPESCA-638/97); the Government of Portugal, Parque Natural de Madeira; the Government of Jamaica, Jamaican Ministry of Foreign Affairs (diplomatic note no. 7/703/315); the Government of Bonaire, Bonaire Marine Park, and Netherlands Ministry of Foreign Affairs (note no. VADV-172/00); the Government of Panama (American Embassy Panama telegram no. 5570); the Puerto Rico Department of Natural And Environmental Resources; the Government of St. Vincent; the Government of France; and the Government of Turks and Caicos (American Embassy London telegram no. 12514). Sampling locations are indicated on the map (
Undetermined samples from the TWA (all HBOI subsamples) were identified to the genus level according to their phylogenetic position relative to known species. Based on this, we selected 71 samples with distinct genotypes for a deeper morphological investigation. For those taxa we examined collection pictures, prepared thick sections and spicule and skeleton stubs for Scanning Electron Microscopy (SEM). We used the methodology outlined in
Genomic DNA was isolated from small pieces of sponge tissue preserved in 70% ethanol using a modified protocol of the DNeasy (Qiagen) Blood and Tissue Kit, which included an additional centrifugation step just before transferring the lysate to the spin column. A Nano-Drop 1000 Spectrophotometer (Thermo Scientific) was used to quantify the isolated genomic DNA. Amplification of a fragment of the mitochondrial cytochrome c oxidase subunit 1 (
Alignments were generated separately for
The Inclusive Phylogenetic Diversity (PDI) is the sum of all branch lengths of a gene tree connecting a set of taxa from the root of the tree to the tips of all phylogenetic branches spanned by this set of taxa (see e.g.,
The relative abundance of eight ‘lithistid’ families from five depth zones (0–60 m; 61–150 m; 151–300 m; 301–600 m; 601–914 m) from the TWA was plotted and illustrated using ggplot2 (
The 296 lithistid sequences of at least 88 species from 27 genera (35 known) constitute the largest and most comprehensive taxon set on desma-bearing tetractinellids to date. Our phylogenies (overview in
(A) 28S (B)
Posterior probability (PP) values are provided above or below branches. Self-generated sequences are in bold. Numbers behind taxon names are either voucher numbers or GenBank/ENA accession numbers. Three letter code behind voucher numbers corresponds to the different locations (GULF, Gulf of Mexico; CUR, Curaçao; BON, Bonaire; GUAD, Guadaloupe; PUE, Puerto Rico; JAM, Jamaica; HON, Honduras; TUR, Turks & Caicos; BAH, Bahamas; FLO, Florida; GAL, Galápagos). Taxa where the morphology was investigated are indicated with their corresponding SBD#.
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The majority (15 out of 23) of the currently known tetractinellid families are located within the Astrophorina (
The family
The genus
The family
The family
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The polyphyletic corallistid genus
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A clade of six as yet unidentified specimens from the HBOI collection (SBD#1814) is sister to the monophyletic
Posterior probability (PP) values are provided above or below branches. Self-generated sequences are in bold. Numbers behind taxon names are either voucher numbers or GenBank/ENA accession numbers. Three letter code behind voucher numbers corresponds to the different locations (GULF, Gulf of Mexico; CUR, Curaçao; BON, Bonaire; GUAD, Guadaloupe; PUE, Puerto Rico; JAM, Jamaica; HON, Honduras; TUR, Turks & Caicos; BAH, Bahamas; FLO, Florida; GAL, Galápagos). Taxa where the morphology was investigated are indicated with their corresponding SBD#.
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The suborder Spirophorina is characterized by sigmaspire microscleres and its members share triaene spicules with Astrophorina. Currently, three families are known: Samidae
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Regarding
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Within the polyphyletic rhizomorine family
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For a better visualization the PDI for the Bahamas are illustrated separately (B) due to their larger number of samples.
Numbers in each bar represent the number of samples investigated. The following genera for each family were included:
In the present study the inclusive phylodiversity was calculated for Bonaire, Curaçao, Florida, Honduras, Jamaica, Puerto Rico, Turks and Caicos and the Bahamas (
The evaluation of the relative abundance of eight ‘lithistid’ families within each depth zone is based upon 234 specimens collected from eight localities in the TWA (
However, further ‘lithistid’ families with a similar bathymetric trend are observed and growth forms are suggested to play a role in the bathymetric distributions of ‘lithistids’. For instance
Further testing is required to assess whether geomorphological conditions resulting of a variety of complex tectonic interactions (e.g., strike-slip faults, thrust fault, subduction and seafloor spreading in Cayman Trough, see
In summary, this is the first integrative approach using molecular and morphological data on TWA ‘lithistid’ demosponges, thus contributing to a better understanding of their phylogenetic affinities, diversity and bathymetric distribution patterns. The present study points to specimens/groups in need of deeper taxonomic investigations and revision, however, additional morphological as well as other independent markers are needed. With recent evidence (
Collection Numbers refer to the Sponge Barcoding Database (SBD#), Bavarian State Collection for Paleontology and Geology (SNSB-BSPG.GW), National Institute of Water and Atmospheric Research (NIWA#), United States National Cancer Institute shallow water collection programme contracted to the Coral Reef Research Foundation (0CDN#), Harbor Branch Oceanographic Institute (HBOI#), California Academy of Sciences Invertebrate Zoology (CASIZ#), Queensland Museum (QMG#), Natural History Museum (BMNH#), personal collection of Michelle Kelly (MKB#), Western Australian Museum (WAM Z#), and the Zoological State Collection Munich (ZSM#).
Thirty-two new specimens and associated data were supplied by the NIWA Invertebrate Collection (NIC) for sequencing; we are particularly grateful to Sadie Mills for her diligent assistance with loans. A further 31 specimens and associated images and data were supplied by Lori J. Bell and the Coral Reef Research Foundation (CRRF) for sequencing; these were collected under contract to the US National Cancer Institute. We thank colleagues Amy Wright, John Reed and Megan Conkling (HBOI-FAU) for their assistance with the HBOI collection of samples and associated data, likewise John Hooper for the Queensland Museum samples (QMG), Cécile Debitus and IRD for Marquesas and Tahiti samples, Jane Fromont and Oliver Gomez for the samples from the Western Australian Museum (WA), and Bernhard Ruthensteiner for access to the collection of the Zoologische Staatssammlung München (ZSM). Patrick Colin, Lori J. Bell, Renata Manconi and one anonymous reviewer are thanked for comments that improved the MS considerably. AS thanks Sergio Vargas for his help with the modification of the phylodiversity script. Nicole Enghuber is thanked for her help in spicule preparations and Simone Schätzle is thanked for sequencing assistance (all at the Dept. of Earth and Environmental Sciences, LMU München, Munich, Germany).
The authors declare there are no competing interests. This document reflects only the authors’ view and the Executive Agency for Small and Medium-sized Enterprises (EASME) is not responsible for any use that may be made of the information it contains.
The following information was supplied relating to field study approvals (i.e., approving body and any reference numbers):
Permission was granted to Harbor Branch Oceanographic Institute by: the United States National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Dry Tortugas National Park (letters of acknowledgement F/SER25:KM, F/SER23:PE, SER02-130) and the Florida Keys National Marine Sanctuary (permit numbers 2001-049, 2001-043); the Government of the Bahamas, Department of Fisheries; the Government of Honduras, Department of Fisheries (DIGEPESCA-638/97); the Government of Portugal, Parque Natural de Madeira; the Government of Jamaica, Jamaican Ministry of Foreign Affairs (diplomatic note no. 7/703/315); the Government of Bonaire, Bonaire Marine Park, and Netherlands Ministry of Foreign Affairs (note no. VADV-172/00); the Government of Panama (American Embassy Panama telegram no. 5570); the Puerto Rico Department of Natural And Environmental Resources; the Government of St. Vincent; the Government of France; and the Government of Turks and Caicos (American Embassy London telegram no. 12514).
The following information was supplied regarding the deposition of DNA sequences:
Novel sequences are archived at the European Nucleotide Archive:
The following information was supplied regarding data availability:
Data is available at the Sponge Barcoding Database:
Data is available at GenBank: