Four new species and one new genus of zoanthids (Cnidaria, Hexacorallia) from the Galapagos Islands Author Reimer, James University of the Ryukyus, Nishihara, Okinawa, Japan Author Fujii, Takuma University of the Ryukyus, Okinawa ,, Japan text ZooKeys 2010 2010-04-01 42 42 1 36 journal article 10.3897/zookeys.42.378 711e535f-366e-4764-9420-fb037cdc5e6a 1313–2970 576650 7E58A32B-DF8A-4795-B0D6-C37CB3B89A0E Terrazoanthus sinnigeri , sp. n. urn:lsid:zoobank.org:act: 2B865570-1FD7-4FB6-BF86-81B5DEDA2289 Figures 4 , 5, 6, 9, Tables 1, 2, 3 Etymology . This species is named for Dr. Frederic Sinniger, who has greatly helped spur the recent phylogenetic reexamination of zoanthid taxonomy. Noun in the genitive case. Material examined. Type locality : Ecuador , Galapagos : Marchena I., Roca Espejo, 0.3125°N 90.4012°W . Holotype : MHNG-INVE-67498. Colony divided into three pieces, on rocks of approximately 2.5 × 2.5 cm, 2.5 × 1.0 cm, and 2.0 × 1.5 cm, with heights of approximately 1.0 cm. Total of approximately 40 polyps connected by stolons. Polyps approximately 1.5–2.0 mm in diameter, and approximately 1.0–2.0 mm in height from coenenchyme. Polyps and coenenchyme encrusted with relatively large pieces of sand clearly visible to the naked eye, tissue of polyps and coenenchyme light brown/ grey in color. In situ, colony was on bottom of rock. Collected from Roca Espejo, Marchena I. , Galapagos , Ecuador , at 9.1 m, collected by JDR , FL , and BR , March 3, 2007 . Preserved in 99.5% ethanol. Paratypes (all from Galapagos , Ecuador ): Paratype 1. Specimen number CMNH-ZG 05886. Glynn’s Reef, Darwin I., at 13 m , collected by FL and AC , March 7, 2007 . Paratype 2. Specimen number USNM 1134067. Glynn’s Reef, Darwin I., at 10 m , collected by JDR , FL , CH , March 7, 2007 . Other material (all from Galapagos , Ecuador ): MISE 464 , Gardner , Floreana I. , 27 m , collected by JDR and AC , March 13, 2007 ; MISE 471 , Devil’s Crown , Floreana I. , 7 m , collected by JDR and AC , March 13, 2007 ; MISE 418 , Punta Espejo , Marchena I. , 7 m , collected by JDR , FL , CH , 0.0ļ substitutions/site Figure 5. Maximum likelihood ( ML ) trees of a mitochondrial 16S ribosomal DNA, and b cytochrome oxidase subunit I ( COI ) sequences for zoanthid specimens. Values at branches represent ML probabilities (>50%). Monophylies with more than 95% Bayesian posterior probabilities are shown by thick branches. Sequences for new species in this study in larger font; sequences newly obtained in this study and new taxa described in this study in bold. Sequences/species names from previous studies in regular font. For specimen information see Table 1. 0.0ļ substitutions/site 0.002 substitutions/site Figure 6. Maximum likelihood ( ML ) tree of internal transcribed spacer of ribosomal DNA (ITS-rDNA) for Terrazoanthus specimen sequences. Values at branches represent ML probabilities (>50%). Monophylies with more than 95% Bayesian posterior probabilities are shown by thick branches. For specimen information see Table 1. March 3, 2007 ; MISE 02-09 , Entrance , Genovesa I. , at 9 m , collected by CH , May 13, 2002 ; MISE 03-560 , Punta Espego , Marchena I. , 7 m , collected by CH , November 12, 2003 ; MISE 434 , Glynn’s Reef , Darwin I. , 13 m , collected by AC and FL , March 7, 2007 ; MISE 442 , Don Ferdi , Bainbridge Rocks , 25 m , collected by AC , March 9, 2007 ; MISE 445 , North Seymour I., 15 m , collected by MV , March 10, 2007 . Figure 7. a–b Cross sections of Antipathozoanthus hickmani sp. n. , MISE specimen 04-345 (details in Table 1) at the actinopharynx region showing preserved histological features. Abbreviations: cm=complete mesentery, ds =dissolved sand “holes”, ec =ectoderm, en =endoderm, g =gonads, im =incomplete mesentery, m =mesoglea, tn =tentacles. Scales = a) 100 µm; b) 50 µm. Sequences : See Table 1. Description . Size : Polyps are approximately 2–8 mm in diameter when open, and rarely more than 10 mm in height. Colonies small, consisting of one polyp (unitary) to less than 50 polyps. Morphology : Terrazoanthus sinnigeri has dull brown, white, or clear oral disks and the outer surface of polyps is heavily encrusted with large particles, with polyps clear of the stolon. Stolons are also heavily encrusted, and approximately the width of polyp diameters. T. sinnigeri has 30 to 36 tentacles that are almost as long or sometimes longer as the diameter of the expanded oral disk ( Figure 4 ). Tentacles often much more transparent than oral disks (when colored). Cnidae : Basitrichs and microbasic p-mastigophores (often difficult to distinguish from each other), holotrichs (large, medium), spirocysts ( Table 2 , Figure 9). Differential diagnosis. In the Galápagos , Terrazoanthus sinnigeri differs from Parazoanthus darwini and Antipathozoanthus hickmani by substrate preference (rock as opposed to sponges and anthipatharians, respectively), as well as from Terrazoanthus onoi sp. n. (above) by both color (brown, white or transparent as opposed to bright red) and microhabitat (under rocks and rubble as opposed to exposed rock surfaces). In addition, T. sinnigeri is smaller (oral disk diameter and polyp height) than congener T. onoi . T. sinnigeri colonies are stoloniferous and generally much smaller than colonies of T. onoi ( Table 3 ). Terrazoanthus sinnigeri can be further distinguished from T. onoi by the presence of many types of nematocysts in the pharynx, unlike T. onoi , which only commonly possesses basitrichs and microbasic p-mastigophores with rare mediumsized holotrichs in the pharynx ( Table 2 ). Terrazoanthus sinnigeri also has small holot- richs, while T. onoi does not ( Table 2 ). Encrustations on the scapus of T. sinngeri are generally much larger than on T. onoi (compare Figures 3 and 4 ). Figure 8. Cross-sections of Terrazoanthus onoi sp. n. , MISE specimen 03-539 (details in Table 1) a Crosssection at the actinopharynx region demonstrating some major features of zoanthids. Note fifth mesentery is complete and therefore specimen is in the suborder Macrocnemina b to e various cross sections of T. onoi at the actinopharynx region showing preserved histological features. Abbreviations: a =actinopharynx, cm =complete mesentery, dd =dorsal directives, ds =dissolved sand “holes”, ec =ectoderm, en =endoderm, im =incomplete mesentery, m =mesoglea, numbers =mesentery numbers from the dorsal directive, sm =sphincter muscle, 5 th =fifth mesentery. Scales = a) 500 µm, b) and e) 100 µm, c) and d) 50 µm. Terrazoanthus sinnigeri is phylogenetically very closely related to T. onoi , but has different and unique ITS-rDNA (see T. onoi description; Figure 6). Similar to Terrazoanthus sinnigeri , there have been reports of other small zoanthids inhabiting cryptic habitats under coral rubble and rock from the Galápagos, Singapore and Japan (J.D. Reimer, T. Fujii, personal observation), but these zoanthids are clearly different in DNA sequence from all known Hydrozoanthidae and Parazoanthidae , and will be described elsewhere. Morphologically, these undescribed zoanthids look very similar to T. sinnigeri , but are often unitary (not colonial), are encrusted with very large pieces of sand, have very little coloring (usually lacking any color asides from around the oral opening) and have fewer tentacles (<26, usually 20–22; data not shown) than T. sinnigeri . Habitat and distribution. Specimens located at depths of 7 to over 27 meters at Floreana, Marchena, Darwin, North Seymour Islands, and Bainbridge Rocks, with other potential specimens observed at other islands. It is likely that this species is widely distributed throughout the Galápagos , and its distribution may extend into deeper waters as it was often found at the lowest depth searched during collection dives. Generally found on the underside of rocks, rubble, or dead shells, often in small cracks or crevices. Biology and associated species. Found under rocks and rubble, Terrazoanthus sinnigeri is often found nearby bryozoans and coralline algae, but appears to not be epizoic on any particular organism. Notes . In Reimer et al. (2008b) it was originally thought that Terrazoanthus sinnigeri (specimens 02-09, 03-560) was a different, white morphotype of T. onoi (mentioned in the paper and Hickman (2008) as Parazoanthus sp. G3) based on COI and mt 16S rDNA sequence data, but given the species’ divergent morphologies, cnidae, and ecologies, as well as different ITS-rDNA sequences, we describe them as closely related but distinct species. It is likely that these two sibling species have recently diverged from one another. Although speculative, it may be that Terrazoanthus sinnigeri ’s preferred habitat un- der rocks has resulted in its lack of bright pigmentation or occasional total lack of pigments compared to bright red T. onoi , which is found in areas more exposed to light, similar as to seen in subterranean invertebrates (e.g. Leys et al. 2003 ), and this should be investigated in the future. Phylogenetic results