Author: Andrew Baird
Species: Acropora teres (Verrill 1866)
This species has confounded coral researchers for many years. The holotype (Fig. 1a) was collected from Amami-Ousima Island in the Ryukyus Archipelago in Japan in 1856 on the US Northern Pacific Exploring Expedition and described as Madrepora teres by Verrill in 1866. The distinctive features of the species are the complete lack of any relief in the radial corallites – they are all entirely immersed along the full length of the branch – and an unusual coenosteum (Fig. 1a) described by Verrill as “strongly vermiculate and sharply scabrous”.
Veron & Wallace 1984 accepted the species as valid. Veron 2000 includes field images of the species from the Philippines and his map suggests it occurs throughout the Indo-Australian Arc. However, it is not possible to see the radials in these images, indeed, the images could be almost any staghorn coral species.
I have never seen a coral in the field with completely immersed radials along the entire length of the branch as in the holotype of A. teres. Radial corallites are often immersed towards the base of the branch in many Acropora species but, in my experience, never along the length of the branch. Indeed, the only coral I have ever seen with such completely immersed corallites is the type of Acropora teres var. distans Wells 1954 USNM 44464 collected from 12 fathoms in the lagoon of Rongelap Atoll (Fig. 2). However, even in this specimen the radials towards the tip of the branch have some relief and the branches of A. teres var. distans are much thinner than the holotype of A. teres.
Dr. Hiro Fukami who has dived extensively in the Amami Islands and throughout Japan, says he has never seen any living coral that matches the holotype of A. teres, despite many hours of searching.
I have just returned from the area in which the holotype was collected in the Amami Islands. I also saw no living colonies that match the holotype. However, it struck me that recently dead fragments of staghorn species that litter the sand in about 1 m depth in the sheltered bays with sandy bottoms that are common in this area look remarkably similar to the holotype (Fig. 1b). When one of these dead fragments is placed next to a living specimen of one of the common staghorn species in the area Acropora cf. cribipora (Dana 1846; Fig. 1c), you can clearly see that the labellate radials could easily eroded to form corallites that appear entirely immersed, similar to the holotype of A. teres. Even the coenosteum looks similar to that of the holotype in the dead fragment.
My guess is that the holotype was dead when it was collected and it is actually a fragment of one the many staghorn species that are common in this habitat in Amami. If I am correct, then Acropora teres (Verrill 1866) is not a valid species. I am not sure what status to give the nominal species seeing as it could be one of many locally abundant staghorn species, therefore there is no obvious synonym. Nonetheless, it is clear to me that the name should stop being used to describe any living specimens.
Project Phoenix thanks Takuma Fujii, Hiro Fukami and James Reimer for excellent advice on the reefs of Amami and Dr. Takahashi Nakamura for securing the permits to collect corals in Kagoshima Prefecture.
Dana, J. D. 1846. Zoophytes. United States Exploring Expedition during the years 1838-1842. Lea and Blanchard, Philadelphia. 7: 1-740.
Wells, J. W. 1954. Recent corals of the Marshall Islands. Bikini and nearby atolls, Part 2, Oceanography (Biology). U.S. Geological Survey Professional Papers. 260-1, pls. 94-185.
Veron, J. E. N., Wallace, C. C. 1984. Scleractinia of Eastern Australia – Part V. Family Acroporidae. Australian Institute of Marine Science Monograph Series 6: 1–485.
Veron J. E. N. 2000. Corals of the World. Australian Institute of Marine Science. Townsville, Australia. 1-1382.
Verrill, A. E. 1866. Synopsis of the polyps and corals of the North Pacific Exploring Expedition, under Commodore C. Ringgold and Capt. John Rodgers, U.S.N., from 1853 to 1856. Collected by Dr. Wm. Stimpson, Naturalist to the Expedition. With descriptions of some additional species from the west coast of North America. Part III. Madreporaria. Communications of the Essex Institute, Salem. 5(3): 17-50, pls. 1-2.