Parazoanthus darwini, Reimer & Fujii, 2010

Reimer, James & Fujii, Takuma, 2010, Four new species and one new genus of zoanthids (Cnidaria, Hexacorallia) from the Galapagos Islands, ZooKeys 42 (42), pp. 1-36 : 14-19

Parazoanthus darwini sp. n.

urn:lsid:zoobank.org:act:9CE65167-B6F8-4CF7-BCF2-BCAF277F9AAC

Figures 2 , 5, 9, Tables 1, 2, 3

Etymology. Named after Charles Darwin, whose 200th birthday was celebrated in 2009. Noun in the genitive case.

Material examined. Type locality: Ecuador, Galapagos: Marchena I., Roca Espejo, 0.3125°N 90.4012°W.

Holotype. MHNG-INVE-67497. Colony divided into three pieces, on rocks of approximately 1.5 × 2.0 cm, with heights of approximately 1.0 cm. Total of approximately 90 polyps conn0ected by very well-developed coenenchyme on top of a white sponge. Polyps approximately 1.0–3.0 mm in diameter, and completely embedded in coenenchyme to 2.0 mm in height from coenenchyme. Polyps and coenenchyme encrusted with black sand, which appear as specks, tissue of polyps and coenenchyme light brown in color. Collected from Roca Espejo, Marchena I., Galapagos, Ecuador, at 8 m, collected by JDR and C. Hickman, Jr. (CH), March 3, 2007. Preserved in 99.5% ethanol.

Paratypes (all from Galapagos, Ecuador):

Paratype 1. Specimen number CMNH-ZG 05884. Roca Espejo, Marchena I., at 8 m, collected by JDR and CH, March 3, 2007.

Paratype 2. Specimen number USNM 1134065. Roca Espejo, Marchena I., at 8 m, collected by JDR and CH, March 3, 2007.

Other material (all from Galapagos, Ecuador): MISE03-47 , Punta Vincente Roca, Isabela I., at 2 m, collected by CH, January 16, 2003 ; MISE03-177 , Gordon Rocks, at 18 m, collected by CH, January 22, 2003 ; MISE03-290 , Cape Douglas, Fernandina I., at 6 m, collected by AC, August 25, 2003 ; MISE03-652 , Tagus Cove, Isabela I., at 13 m, collected by CH, November 16, 2003 ; MISE04-155 , La Botella, Floreana I., at 12 m, collected by AC, May 25, 2004 ; MISE04-184 , Las Marielas, Isabela I., at 6 m, collected by AC, December 2, 2004 ; MISE04-328 , Las Marielas, Isabela I., at 3 m, collected by AC, December 2, 2004 ; MISE04-348 , Caleta Iguana, Isabela I., at 9 m, collected by CH, December 3, 2004 ; MISE 412 , Roca Espejo, Marchena I., 6 m, collected by JDR and CH, March 3, 2007 ; MISE413 , Roca Espejo, Marchena I., 7 m, collected by JDR and CH, March 3, 2007 ; MISE417 , Roca Espejo, Marchena I., no depth given, collected by CH, March 3, 2007 ; MISE 424 , Roca Espejo, Marchena I., 9 m, collected by JDR, F. Liss ( FL), B. Riegl ( BR), March 3, 2007 ; MISE425 Roca Espejo, Marchena I., 9 m, JDR, FL, BR, March 3, 2007 ; MISE428 El Elefante, Wolf I., 24 m, collected by D. Ruiz (DR) and F. Riveira (FR), March 5, 2007 ; MISE429 El Elefante, Wolf I., 21 m, collected by DR and FR, March 5, 2007 ; MISE430 El Elefante, Wolf I., 22 m, collected by JDR, O. Breedy ( OB), BR (FR), March 5, 2007 ; MISE431 El Elefante, Wolf I., 22 m, collected by JDR, OB, BR, March 5, 2007 ; MISE450 Crater at Gordon’s Rock, 17 m, collected by JDR, March 11, 2007 ; MISE451 Crater at Gordon’s Rock, 21 m, collected by JDR, March 11, 2007 ; MISE452 Crater at Gordon’s Rock, 17 m, collected by AC, March 11, 2007 ; MISE456 Whale Rock, San Cristobel I., 17 m, collected by JDR, March 12, 2007 ; MISE458 Kicker Rock, San Cristobel I., 15 m, collected by JDR, March 12, 2007 ; MISE461 Baho Garden, Espanola I., 10 m, collected by M. Vera ( MV), March 12, 2007 ; MISE466 Gardner, Floreana I., 15 m, collected by JDR and AC, March 13, 2007 ; MISE468 Gardner, Floreana I., 14 m, collected by JDR and CH, March 13, 2007 ; MISE470 Devil’s Crown, Floreana I., 9 m, collected by JDR and MV, March 13, 2007 .

Sequences. See Table 1.

Description. Size: Polyps are approximately 3–6 mm in diameter when open, and approximately 2–6 mm in height. Colonies may be very small (a few cm 2 in area), or extend to cover large areas over a square meter in area.

Morphology: Parazoanthus darwini polyps have yellow, orange, or cream tentacles, and a red, yellow, or light yellow oral disk, with a light tan, light pink, or cream coenenchyme. Polyps have between 24 and 30 tentacles that are usually longer than expanded oral disk diameter. Although polyps extend clear of the coenenchyme, when contracted the polyps are mere bumps on the surface of the coenenchyme.

Cnidae: Basitrichs and microbasic p-mastigophores (often difficult to distinguish), holotrichs (medium and small), spirocysts (see Table 2, Figure 9).

Differential diagnosis. In P. darwini , the polyps are much more embedded in the coenenchyme than those of both A. hickmani and Hydrozoanthidae species of the Galápagos ( Table 3). Whereas many Parazoanthus species from other areas of the world are epizoic on sponges, none are morphologically similar (color, size, polyp shape; see below) to P. darwini . Parazoanthus axinellae and P. catenularis Duchassaing de Fonbressin & Michelotti 1860 from the Caribbean are found on clearly different host sponges from P. darwini . Parazoanthus swiftii Duchassaing de Fonbressin & Michelotti, 1860 and P. parasiticus Duchassaing de Fonbressin & Michelotti, 1860 are somewhat similar to Parazoanthus darwini in both polyp and coenenchyme color, but have fewer tentacles (maximum to 28; sensu Swain 2009) than P. darwini , and clearly different mitochondrial 16S ribosomal DNA ( Reimer et al. 2008b).

Habitat and distribution. Similar to Terrazoanthus onoi sp. n. (below), specimens of Parazoanthus darwini are found on rock walls, in crevices, or at the base of rocks, and were found from depths of 2 m to ̴ 30 m, and may extend deeper. Colonies of P. darwini were seen at Wolf, Marchena, Isabela, Fernandina, Santa Cruz, San Cristobal, Española and Floreana Islands, and its range is likely throughout the archipelago.

Biology and associated species. Collected Parazoanthus darwini specimens from Galapagos are often (but not always) associated with different species of bright yellow-orange or red sponges, possibly in the groups Poecilosclerida and/or Hadromerida (T. Swain, personal communication). P. darwini colonies often grow in patches over the sponge, or may even cover it entirely, and often extend to surrounding rock substrate. Despite being covered by P. darwini , the sponge is always alive, suggesting this association may be symbiotic.

Notes. Despite COI and mt 16S rDNA sequences of this species being identical to sequences from Parazoanthus swiftii from the Caribbean (Figures 5a, 5b), slightly longer mt 16S rDNA sequences ( Figure 2 in Reimer et al. 2007) were not identical. Additionally, due to the morphology of P. swiftii (rarely not on sponges, relatively shorter tentacles, large [6 mm] diameter polyps that often extend well out from coenenchyme) and large geographic distances between P. swiftii and P. darwini localities, it is clear that these are two different species.

Previously mentioned in Reimer et al. (2008b) and Hickman (2008) as Parazoanthus sp. G2.

Family Hydrozoanthidae Sinniger, Reimer & Pawlowski, 2009

Diagnosis (from Sinniger et al. 2009):

Tropical and sub-tropical macrocnemic zoanthids associated with hydrozoans or associated with non-living substrate. Includes former Parazoanthidae species sharing specific insertions and deletions in mt 16S rDNA, especially in the V5 region (as defined in Sinniger et al. 2005) of this gene. Phylogenetically species are more closely related to brachycnemic zoanthids (especially from the genus Palythoa Lamouroux 1816 ) than to other parazoanthids.

Figures

Figure 2. Parazoanthus darwini sp. n. in situ in the Galapagos. a specimen MISE 451 at Gordon Rocks, depth 21 m, by JDR, March 11, 2007 b specimen 456 on orange sponge at Whale Rock, San Cristobel I., depth 17 m, by JDR, March 12, 2007 c close up of specimen 03-290, Cape Douglas, Fernandina Island, 6 m, by Angel Chiriboga, August 8, 2003. All scale bars: 1 cm.