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| Pavona giannii Benzoni, 2025 |
Abstract
Hard coral species in the agariciid genus Pavona are common in shallow and mesophotic coral reef communities across the Indo-Pacific, but their taxonomy has long been overlooked. Pavona giannii sp. nov. is here described based on newly collected material across the Indian Ocean, and historical museum specimens. In vivo and skeletal morphological features are described, diagnostic characters measured, and comparison with congeners performed. The new species forms an encrusting corallum devoid of raised ridges on its surface. Its corallites are flush with the surface, not inclined, and less than half a corallite diameter apart. Corallites arrangement is thamnasteroid and series can form locally. Where they occur, the radial elements run over the shared walls to the adjacent series’ corallites creating a ladder-like arrangement similar to that observed over the ridges in congeners like Pavona varians and Pavona chiriquiensis. Despite the lack of ridges, P. giannii sp. nov. has morphological affinities with these two species. However, based on previously published morphometrics and meristics, P. giannii sp. nov. corallites are larger and more crowded, and the primary septa are longer and more numerous. In vivo, the new species is distinguished by fully extended white to beige tentacles during the daytime, giving it a white-bearded appearance. Despite the ecological relevance of Pavona corals, a taxonomic revision of the genus is overdue, and the existing molecular studies indicate that it is polyphyletic. Here, the proposed placement of P. giannii sp. nov. in the genus is based on morphological evidence alone and phylogenomic analyses are currently in progress.
Key words: Morphometrics, museum collections, reef-building coral, skeletal morphology, taxonomy
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| Holotype of Pavona giannii sp. nov. MNHN-IK-2012-14233 A. the whole colony in situ at Hyllanyia Island, Bir Ali, Yemen, prior to sampling and B. corallum of the sampled fragment. C. Top view of the corallum showing corallite arrangement and the position of some of the corallite series boundaries (dashed pink lines) marked by the presence of parallel radial elements running over and across them, and D. side view showing its even surface given by equally high and flat top margins of S1 and S2 septa, and the deep-seated fossae. Scale bars: 1 cm (B); 5 mm (C, D). |
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| Pavona giannii sp. nov. in situ. A. Typically white extended tentacles in the colony, from which specimen UNIMIB BAL252 was collected, encrusting a submassive Porites (living portion at the top right-hand side) at Balhaf, Yemen; B. Colony of UF 17957, Mirbat, Oman; C. Fully extended white tentacles covering the whole surface of the colony of UNIMIB SO078 at Socotra Island, Yemen; D. Colony with partially retracted tentacles allowing the polyps’ white oral disks to show, Mahé Island, Seychelles; E. Colony of UNIMIB MY069 at Mayotte Island; F. Colony with white tentacles and grey oral disks Balhaf, Yemen; G. Close-up of the polyps of colony UNIMIB BU049 with beige tentacles and white oral disks at Burum, Yemen. |
Francesca Benzoni. 2025. A New Reef-dwelling Coral, Pavona giannii sp. nov. (Scleractinia, Agariciidae), with an overview of the skeletal morphology of the type specimens of the genus Pavona. ZooKeys. 1260: 123-147. DOI: doi.org/10.3897/zookeys.1260.167263
