In 2020 when Project Phoenix launched this website, we promised a revolution and thanks to some excellent work led by Dr Sage Rassmussen, we have just delivered with a taxonomic revision of the Acropora hyacinthus species complex (Rassmussen et al. 2025). 

To quote the singer-songwriter Tracy Chapman and to paraphrase the title of the paper published in the journal Invertebrate Systematics;

“Finally the tables are starting to turn
Talkin’ ’bout revolution” 

In the paper, the international group of scientists of Project Phoenix and colleagues continues to reinvent coral taxonomy using several significant and novel approaches. In particular, 

1. testing all the nominal species in the group and their putative synonyms, not just the currently accepted species
2. the explicit use of topotypes to test these nominal species, and
3. an attempt to address the issue of conflicting “lines of evidence” in species delimitation.

The results are quite extraordinary. We demonstrate that A. hyacinthus as defined in recent taxonomic/identification material (e.g. Wallace 1999; Veron 2000) is not a single widespread species but rather a complex of 17 or more species, most with relatively restricted geographical ranges. For example, on the Great Barrier Reef there are up to four different species that have been identified as A. hyacinthus at many locations. The results demonstrate that the taxonomic framework that has guided coral identification for the last 20 years for this group is unworkable. In this case, only 3 of over 17 species in the hyacinthus-group are mentioned in Veron (2000). 

Below we summarise the numerous taxonomic actions in the paper.

First, we confirm the validity of two currently accepted species:

• Acropora hyacinthus (Dana, 1846)
• Acropora spicifera (Dana, 1846)

We remove four species from synonymy with A. hyacinthus and confirm their validity:

• Acropora pectinata (Brook, 1892) 
• Acropora conferta (Quelch, 1886)
• Acropora turbinata (Verrill, 1864)
• Acropora bifurcata Nemenzo, 1971

We remove five species from synonym with A. hyacinthus (Dana, 1846) based on comparisons with the type material or the geographical location of the types, but cannot confirm their validity due to a lack of topotypes:

• Acropora sinensis (Brook, 1893)
• Acropora flabellifiorms (Milne-Edwards, 1860)
• Acropora recumbens (Brook, 1892)
• Acropora surculosa (Dana 1846)
• Acropora patella (Studer, 1878)

We designate a nomen novum for Acropora pectinata (Veron, 2000) – Acropora floresensis Rassmussen nomen novum.

We designate Acropora microclados (Ehrenberg, 1834) a nomen dubium having revisited the original description, subsequent revisions and the putative type material in the Museum fur Naturkunde, Berlin. This essentially means that Ehrenberg’s species description is untestable and that the name should no longer be used. 

We also suggest that Acropora anthocercis sensu Veron & Wallace (1984) on the Great Barrier Reef is an undescribed species and we name Acropora kalindae sp. nov. In fact, in the group examined, there are at least 11 undescribed species, five of which are supported by more than five of the 10 lines of evidence examined (Figure 1):

• Acropora tersa Rassmussen, Bridge & Baird, sp. nov.
• Acropora harriottae Baird and Rassmussen, sp. nov.
• Acropora uogi Randall, Burdick & Bonito, sp. nov.
• Acropora nyinggulu Bridge & Rassmussen sp. nov.
• Acropora kalindae Crosbie, Baird, Bridge, and Rassmussen sp. nov.

We also suggest that Acropora anthocercis (Brook, 1893) has not been sampled since the 1890s. An extensive search in the Worldwide Acropora collection at the Museum of Tropical Queensland found no specimens that match the lectotype designated by Wallace (1999) which was collected by Saville-Kent in the Palms Islands, GBR in the 1890s and described by Brook (1893). Our extensive searches for a topotype throughout the Palm Islands group and along the length of the GBR have also failed to find any specimens that match the lectotype.

All these changes in one small sub-clade within the mega-diverse Acropora clade VI sensu Cowman et al. 2020! Our unpublished data indicate similar taxonomic changes are required throughout the order Scleractinia.