BULLETIN OF MARINE SCIENCE. 89(3):735–743. 2013 NEW TAXA PAPER http://dx.doi.org/10.5343/bms.2013.1014 http://zoobank.org/urn:lsid:zoobank.org:pub:E62C6099-A6E3-43E0-8F43-014ED71DA0D5 A NEW SPECIES OF THE GENUS EUGORGIA (CNIDARIA: OCTOCORALLIA: GORGONIIDAE) FROM MESOPHOTIC REEFS IN THE EASTERN PACIFIC Odalisca Breedy and Hector M Guzman ABSTRACT Our knowledge of octocoral diversity in the eastern Pacific has been focused on shallow reef habitats, while the fauna occurring in the mesophotic zone from 40 to 150 m is poorly known. A new species of the gorgoniid Eugorgia was recently obtained with a submersible from the Hannibal Bank, a coastal seamount 60 km off mainland Panama and 15 km from Coiba Island. The morphological characters were analyzed and illustrated by light and scanning electron microscopy. Eugorgia siedenburgae sp. nov. can be distinguished from the other species in the genus by its bushy, multiplanar, bicolored colony, and the sclerites colors, composition, and sizes. This new species increases the number in the genus to 13 and contributes to our understanding of the fragile mesophotic biodiversity. Octocoral diversity surveys in the eastern Pacific region have been focused mainly on shallow environments to 40 m depth (e.g., Williams and Breedy 2004, Breedy et al. 2009, Breedy and Guzman 2012). Consequently, the fauna inhabiting mesophotic habitats from 40 m to >150 m is poorly described and may be at risk due to intensive fishing (see Lesser et al. 2009, Clark et al. 2010). Here, we describe a new species of the gorgoniid Eugorgia recently collected from the Hannibal Bank seamount, Pacific Panama. The genus Eugorgia (family Gorgoniidae) is considered to be exclusively east- ern Pacific (from Southern California to Peru), it is found mostly from 10 to 40 m. Eugorgia rubens Verrill, 1868 has the deepest records from 50 to 60 m, obtained mostly from fishing nets or dredging. Eugorgia is characterized by having flabellate to bushy colonies with one or multiple planes. Branching is lateral, partially dichoto- mous, or pinnate-like, often bushy, and combinations of both; branch anastomosis is absent, but pseudo-anastomosis frequently occurs (Breedy et al. 2009). The colonies have a horny axis, which has a narrow cross-chambered central core with a network of organic filaments frequently mineralized with deposits of carbonate hydroxyl apa- tite. The holdfast could be attached to hard substrates, debris, and coarse sand or muddy sediments. Polyps are fully retractile into the coenenchyme, in slightly raised to prominent mounds arranged in series of longitudinal rows, or evenly distributed on the branches. Coenenchymal sclerites are of various types: spindle, disc-spindle, capstan, and the most dominant form that defines the genus is the characteristic double disc. Anthocodial sclerites are rarely found. Color of colonies and sclerites is variable: colorless, yellow, orange, red, violet, brownish, or combinations of these (Breedy et al. 2009). According to the morphological features, the species are pro- posed to form three groups, the daniana-group, the ampla-group, and the mono- specific rubens-group (see Breedy et al. 2009). There are seven species of Eugorgia reported for the Pacific coast of Costa Rica and Panama. Bulletin of Marine Science 735 © 2013 Rosenstiel School of Marine & Atmospheric Science of the University of Miami 736 BULLETIN OF MARINE SCIENCE. VOL 89, NO 3. 2013 Figure 1. Eugorgia siedenburgae sp. nov. (STRI 1227), collection of the holotype, Hannibal Bank, 65 m deep. DeepSee photograph. Materials and Methods Study Site and Collection Methods.—Samples were collected in the Hannibal Bank (07°26.194´N, 082°4.508´W), a coastal seamount located 60 km off mainland Pacific Panama. The seamount is an elongated, triangular guyot, 14.4 km long and 7.1 km wide, and ranging in depth from 45 m on rugose areas at the top of the seamount to 416–500 m at the bottom of the steep slope. The bank covers an area of 76 km2. The seamount is geologically com- plex with fragments of oceanic plate, spreading centers, hotspot traces such as the Cocos, Malpelo, and Carnegie Ridges together with sedimentary units typical in nearshore to shelf areas (Cunningham et al. in press). The bank is unaffected by seasonal upwelling and is part of the Coiba National Park and a World Heritage Site, administered as special management fishing area encompassing 1781 km2. Several specimens were observed and photographed from the submersible DeepSee (UnderSea Hunter Group), and collected using a mechanical arm (Model Orion, Shilling Robotics USA) in March 2012 during a Smithsonian Tropical Research Institute expedition (Fig. 1). All specimens were deck-photographed and dried and/or preserved in 95% ethanol. Additional specimens were used for the description of the species, collected by bottom trawl- ing from Santa Elena Bay (10°55.155´N, 085°48.573´W), a contrasting seasonal upwelling area located on the north Pacific coast of Costa Rica. Morphological Study.—For microscopic study, specimens were prepared for light mi- croscopy and SEM following the protocol described in Breedy and Guzman (2002) and for assessment of characters we followed Verrill (1868) and Breedy et al. (2009). Morphological characters of colonies and sclerites are presented in Table 1, and comparison with the type material of the related taxa in the genus. The holotype and paratypes from Panama are depos- ited in the Smithsonian Tropical Research Institute (STRI) and paratypes from Costa Rica at the Museo de Zoología, Universidad de Costa Rica (MZUCR, former UCR). Terminology used in descriptions mostly follows Bayer et al. (1983), Breedy and Guzman (2002), and Breedy et al. (2009). BREEDY AND GUZMAN: A NEW EUGORGIA FROM MESOPHOTIC REEFS 737 Results The new species was determined through the comparison of its morphological characteristics with the closest taxa (see Table 1). Class Anthozoa Ehrenberg, 1831 Subclass Octocorallia Haeckel, 1866 Order Alcyonacea Lamouroux, 1812 Family Gorgoniidae Lamouroux, 1812 Genus Eugorgia Verrill, 1868 Eugorgia siedenburgae new species (Figs. 1–4) Holotype.—STRI 1227, Hannibal Bank, Coiba Island, Gulf of Chiriquí, Panama, 63 m, DeepSee Dive 1553, 10 March, 2012. Paratypes.—Panama: STRI 1221–1222, 1232, 1239, 1242, 1246, Hannibal Bank, Coiba Island, Gulf of Chiriquí, 63 m, DeepSee Dive 1553, 10 March, 2012. Costa Rica: MZUCR 2272, 2276, ethanol preserved, trawl 46, 54.2 m, Y Camacho, 9 July, 2005; MZUCR 2278, dry, trawl T20, #1, Bahía Santa Elena, R/V Urraca Expedition, trawl 20, #1, 50–52 m, Y Camacho, 9 July, 2005; MZUCR 2280, dry, Bahía Santa Elena, R/V Urraca Expedition, trawl 4, #3, 50–52 m, Y Camacho, 9 July, 2005; MZUCR 2281, dry, Bahía Santa Elena, Guanacaste, Costa Rica, R/V Urraca Expedition, trawl 4, #15, 50–52 m, Y Camacho, 9 July, 2005. Diagnosis.—Bushy, stout colony, profusely branched in several planes, branching irregularly pinnate, subdividing up to 10 times, pseudo-anastomosis present (Fig. 2A), prominent polyp-mounds up to 0.70 mm tall, arranged in two or three lateral rows and sparsely and irregularly distributed (Fig. 2B). Colony bright pink to reddish orange fading toward the tips to orange or pale pink (Fig. 2A,B). Sclerite colors: dif- ferent combination of red, pink, light yellow, and bicolored (Fig. 2C). Spindles and disc spindles up to 0.11 mm, double discs and capstans mostly 0.07–0.075 mm, scant complete double discs up to 0.07, and crosses around 0.07 × 0.07 mm. No anthoco- dial rods. Description.—Holotype 42 cm tall, and 26 cm wide, bushy colony, profusely branched, growing in several planes (Fig. 2A). Branching irregularly pinnate, several pseudo-anastomosis occurs in branchlets and branches. Main stem 8 mm diameter, slightly compressed, and short, 1.5 cm long arising from a conical holdfast, 3.4 cm wide and 2.4 cm tall. Main stem subdividing in multiple branches, 2.0–3.0 mm di- ameter emerging at angles of 30°–45° and producing secondary branches giving off thin branchlets, 1–1.5 mm diameter, including polyp-mounds. Branchlets irregularly arranged and closely spaced, separated 1–15 mm, and giving off 1–3 lateral, second- ary branchlets, which are of same thickness and closely placed. Branchlets 2–30 mm long. Branching up to 10 times. Unbranched terminal twigs blunt, and reach up to 30 mm long (Fig. 2A,B). Polyps white. Polyp-mounds prominent, up to 0.70 mm height and 1.0 mm in diameter, arranged in two or three lateral rows along the branchlets, 738 BULLETIN OF MARINE SCIENCE. VOL 89, NO 3. 2013 Color rings Color y no no no no sclerite color sclerite Coenenchymal Coenenchymal p p,y r, y r, y r, y Bicolor colony colony Bicolor X no no no no colony Color of of Color r p p,o do, r do, r Anth. rods Anth. ). The characteristics are based on are based characteristics The ). 0.08 not found not found not found not found Eugorgia Crosses no 0.06 × 0.06 × 0.078 × 0.071 0.075 × 0.065 -group (genus spindles Bent X X X no no rubens Spindles 0.11 0.11 0.10 0.13 0.13 Disc-spindle no 0.11 0.10 0.13 0.13 Capstans no 0.07 0.07 0.07 0.07 group and with the group and Double disc Double 0.08 0.07 0.07 0.08 0.07 double disc double daniana- Complete Complete no no 0.067 0.065 0.043 distribution Polyp Polyp irr irr irr reg reg , within the , within length length Branchlet Branchlet 2–30 1–10 2–30 1–15 6–30 diameter diameter Branchlet Branchlet 1.5–2.0 1.0–1.5 1.0–1.5 1.0–1.5 1.0–2.5 distance Branchlet Branchlet Eugorgia siedenburgae siedenburgae Eugorgia 6.0–20.0 1.0–4.0 1.0–15.0 1.0–4.0 1.5–8.0 of branching of Max number number Max 5 7 7 6 10 type Branching Branching lb irr-pi irr-pi irr-pi irr-pi Colony growth Colony bu pla pla pla spa sp.