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Terrazoanthus onoi sp. n.
Figures 3View Figure 3, 5, 6, 8, 9, Tables 1, 2, 3
Etymology. This species is named in honor of Dr. Shusuke Ono, who introduced the first author to zoanthids and has played a major role in zoanthid research in Japan. Noun in the genitive case.
Material examined. Type locality: Ecuador, Galapagos: Espanola I., Anchorage, 1.3646°S 90.2953°W.
Holotype: MHNG-INVE-67496. Colony on rock, approximately 3.0 × 6.0 cm. Total of approximately 130 polyps connected by well-developed coenenchyme. Polyps approximately 1.0–3.0 mm in diameter, and approximately 0.5–2.0 mm in height from coenenchyme. Polyps and coenenchyme encrusted with sand, tissue of polyps and coenenchyme dark brown in color. Collected from Anchorage, Espanola I., Galapagos, Ecuador, at low tide line, collected by AC, March 12, 2007. Preserved in 99.5% ethanol.
Paratypes (all from Galapagos, Ecuador):
Paratype 1. Specimen number CMNH-ZG 05885. Glynn’s Reef, Darwin I., at 13 m, collected by FL and AC, March 8, 2007.
Paratype 2. Specimen number USNM 1134066. Whale Rock, San Cristobel I., at 21 m, collected by JDR, March 12, 2007.
Other material (all from Galapagos, Ecuador): MISE 02-59, Punta Vincente Roca, Isabela I., at 9 m, collected by CH, May 20, 2002 ; MISE 03-46, Punta Vincente Roca, Isabela I., at 2 m, collected by CH, January 16, 2003 ; MISE 03-135, Roca Onan, Pinzon I., depth not available, collected by L. Vinueza (LV), January 20, 2003 ; MISE 03-566, Punta Espejo, Marchena I., at 9 m, collected by CH, November 12, 2003 ; MISE 03-641, Punta Vincente Roca, Isabela I., depth not available, collected by CH, November 15, 2003 ; MISE 04-140, La Botella, Floreana I., at 8 m, collected by AC, February 8, 2004 ; MISE 04-343, Caleta Iguana, Isabela I., depth not available, collected by GE, December 3, 2004 ; MISE 04-345, Caleta Iguana, Isabela I., at 8 m, collected by CH, December 3, 2004 ; MISE 04-346, Elizabeth Bay , Isabela I., at 25 m, collected by GE, December 2, 2004 ; MISE 04-347, Elizabeth Bay , Isabela I., at 13 m, collected by CH, December 2, 2004 ; MISE 467, Gardner, Floreana I., 14 m, collected by JDR and CH, March 13, 2007 ; MISE 469, Devil’s Crown, Floreana I., 12 m, collected by JDR and MV, March 13, 2007 ; MISE 473, La Botella, Floreana I., at 12–15 m, collected by AC, March 13, 2007 ; MISE 475, Roca Onan, Pinzon I., 8 m, collected by AC, March 14, 2007
Sequences. See Table 1.
Polyps are approximately 4–12 mm in diameter when open, and rarely more than 20 mm in height. Colonies may reach sizes of over a meter in diameter.
Morphology: Terrazoanthus onoi has bright red or red-brown oral disks and the outer surface of polyps is tan to dark brown, with polyps relatively clear of the coenenchyme. T. onoi has 32 to 40 tentacles that are almost as long as the diameter of the expanded oral disk ( Figure 3View Figure 3).
Cnidae: Basitrichs and microbasic p-mastigophores (often difficult to distinguish), holotrichs (large, medium, and small), spirocysts (see Table 2, Figure 9).
Differential diagnosis. In the Galápagos, Terrazoanthus onoi differs from Parazoanthus darwini and Antipathozoanthus hickmani by substrate preference (rock as opposed to sponges and anthipatharians, respectively), as well as from Terrazoanthus sinnigeri sp. n. (below) by both color (bright red as opposed to brown, white or transparent) and habitat ecology (exposed rock surfaces as opposed to under rocks and rubble). In addition, T. onoi is bigger (oral disk diameter and polyp height) than T. sinnigeri , and forms much larger colonies ( Table 3). T. onoi commonly has only basitrichs and microbasic p-mastigophores in its pharynx, and no large or small holotrichs at all, unlike T. sinnigeri ( Table 2).
Phylogenetically, Terrazoanthus onoi is very closely related to T. sinnigeri , with identical COI and mt 16S rDNA sequences, but consistently differs by four base pairs in ITS-rDNA, and forms a clade separate from T. sinnigeri .
An extensive literature search revealed no other described Parazoanthidae species from the Pacific that are non-epizoic and bright red in color. An undescribed zoanthid species inhabiting rock and coral reef substrata from Indonesia often referred to as “yellow polyps” (sensu Sinniger et al. 2005) is likely also a Terrazoanthus sp., but is distinct from T. onoi in terms of color and distribution, and is phylogenetically different.
Habitat and distribution. Specimens of Terrazoanthus onoi were found on rock substrate in areas of high current (i.e., the base of large rocks, rock walls, etc.). Colonies were found at Darwin, Marchena, Genovesa, Isabela, Pinzon, Española, and Floreana Islands, and it is likely T. onoi is found throughout the archipelago. This species has been found from the low infra-littoral to depths of over 35 m, and is likely to be at even deeper depths.
Biology and associated species. Found on the top surfaces of rocks and biogenic non-living substrate, Terrazoanthus onoi is often found close to sponges, seaweed, and oth- er benthos, but is not epizoic and does not have an association with any particular species.
Notes. Previously mentioned in Reimer et al. (2008b, 2010) and Hickman (2008) as Parazoanthus sp. G3, except for specimen MISE 02-27 mentioned below.
It should be noted that specimen MISE 02-27 was found to have an ITS-rDNA sequence inconsistent with other Terrazoanthus onoi specimens (Figure 6), although other data (morphology, mt 16S rDNA and COI data) fit well with T. onoi . For these reasons, this specimen has not been conclusively assigned to T. onoi or to the other new Terrazoanthus species below. These results indicate there may be other Terrazoanthus species in the Galápagos that await discovery and description.
Amherst College, Beneski Museum of Natural History
Smithsonian Institution, National Museum of Natural History
University of Montana Museum
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