Eugorgia mutabilis, Breedy, Odalisca, Williams, Gary C & Guzman, Hector M, 2013

Breedy, Odalisca, Williams, Gary C & Guzman, Hector M, 2013, Two new species of gorgonian octocorals from the Tropical Eastern Pacific Biogeographic Region (Cnidaria, Anthozoa, Gorgoniidae), ZooKeys 350, pp. 75-90 : 79-82

Eugorgia mutabilis sp. n. Figs 4-6

Material examined.

Holotype. UCR 2297, ethanol preserved, Burbujas, between Los Potreros and Playa Arenitas, Puerto Jiménez, Golfo Dulce, Costa Rica, 11 m, O. Breedy, 9 May 2013. Paratypes. UCR 2298, same data as the holotype. UCR 2272, 2276, fragments, ethanol preserved, Burbujas, 12 m, C. Sánchez, May 2012. UCR 2299, fragment, ethanol preserved, Roca Matapalo, Cabo Matapalo, Golfo Dulce, 20 m, O. Breedy, 6 February 2009. STRI 408, dry, Isla Seca Grande, Gulf of Chiriquí, Panamá, 20 m, H. Guzman, 26 August 2002. STRI 444, dry, Isla Jicarita, Gulf of Chiriquí, 20 m, H. Guzman, 29 August 2002. STRI 511, dry, Isla Ladrones, Gulf of Chiriquí, 15 m, H. Guzman, 14 April 2003. STRI 1073, Santa Cruz, Coiba Island, Panamá, 15 m, H. Guzman, 27 April 2007. STRI 1076, Twin Peaks, Coiba Island, 15 m, H. Guzman, 27 April 2007. STRI 1168, fragment, ethanol preserved, Bajo Hacha, Coiba Island, 20 m, O. Breedy, 16 April 2009. STRI 1122, ethanol preserved, La Blanca, Oxaca, Mexico, 46 m, R. Abeytia, 29 August 2004.

Type locality.

Puerto Jiménez, Golfo Dulce, Costa Rica, 11 m.

Diagnosis.

Broad, stout, flabellate colony, main branches sinuous, branching irregularly pinnate, subdividing 5-7 times, no anastomosis present. Prominent polyp-mounds closely spaced and irregularly distributed around branches and branchlets (Figs 4, 6A-C). Colony white, pale pink when alive (Fig. 6 A–C), dark grayish when dry or ethanol preserved. Change in color after collection very conspicuous. Longitudinal grooves evident along branches and branchlets. Sclerites white. Spindles and disc-spindles up to 0.15 mm long, double discs mostly 0.05-0.08 mm long. Sclerite discs sharp, serrated and prominent. No anthocodial rods found.

Description.

Holotype 30 cm tall, and 47 cm wide; colony broad, flabellate, very flexible. Branching irregularly pinnate. Main stem 6 mm diameter, laterally flattened, and short, 14 mm long. Holdfast oval, 40 mm diameter without polyps. Main stem subdividing in 5 sinuous main branches. Main branches slightly flattened on plane of colony, 3-4 mm in diameter emerging at angles of about 45°, bifurcating and diverging producing five flat pinnate fronds of long pinnate branchlets (Fig. 4 A–B). Pinnae short, up to 8 mm long, and 1.5-2 mm diameter including polyp-mounds, close together 1-3 mm apart. Branching up to 7 times. Unbranched terminal twigs blunt, and reach up to 8 mm long (Fig. 4 A–B). Longitudinal grooves distinct along branches and pinnate branchlets, evident in living and preserved specimens. Polyps white (Fig. 4B). Polyp-mounds prominent, up to 0.7 mm height and 0.8 mm in diameter, arranged mostly in lateral rows along the branchlets and separated by the longitudinal grooves, and more sparsely and irregularly distributed along the thicker branches (Fig. 4B). Colony white to pale pink when alive, gray to dark grayish in ethanol/dry preservation (Fig. 4A). Change in color very conspicuous possibly by liberation of black pigments after collection. Sclerites of coenenchyme white. Sclerite discs conspicuous mostly sharp, serrated and prominent (Fig. 4C, 5 A–B). Disc-spindles 0.08-0.12 mm long, and up to 0.06 wide with 4-5 whorls of discs (Fig. 5B); spindles and disc-spindles, longer and thinner up to 0.15 mm long and 0.05 mm wide, with 5-7 whorls of warty tubercles, the ends acute, blunt, or both (Fig. 5A). Double discs up to 0.08 mm long, and 0.05 mm wide with prominent discs (Fig. 5B), some almost complete (Fig. 5B). No crosses, capstans or anthocodial sclerites present in samples.

Variability.

The specimens present some variation in sclerite color, white sclerites being dominant, but some pale yellow hues could be observed in the samples. In all other aspects they agree with the holotype, including the change of color from bright white alive or recently collected to grayish when fixed. It is interesting that after collection, the specimens discharge a black pigment that turns the water black or the alcohol, and the colony becomes gray. The specimens from Mexico represent the deeper record; they have been observed down to 50 m, meaning that the range of depth extends from 40 to 50 m as it is for Eugorgia rubens , Eugorgia siedenburgae , and Eugorgia beebei , but the morphology of the colony and sclerites remain the same described for Eugorgia mutabilis . Current flow and depth are some of the environmental factors that could influence interspecific variability in octocorals ( Fabricius and Alderslade 2001), but in this case no effect was observed. The morphology of the colony and sclerite content are persistent along the depth range.

Remarks.

The species was mentioned before as a variety of Eugorgia daniana : 'a white variety has been observed in shoals in Costa Rica and Mexico occurring together with the red form’ ( Breedy et al. 2009). However, after examination of many specimens from various localities and depths, we found enough differences with respect to Eugorgia daniana , and to the other species in the group, especially in the color and the conspicuous sclerites, to establish Eugorgia mutablilis as a new species.

Habitat.

The new species is found on rocky substrates, in general with other species of gorgonians, including Eugorgia daniana , but in some places, it is the only Eugorgia present (Fig. 6 A–C). Other gorgonians found normally inhabiting the same localities are Pacifigorgia irene , Pacifigorgia stenobrochis , Leptogorgia alba , and Carijoa riseii , which were very abundant in the type locality. A variety of associated invertebrates were found on the holotype and paratype UCR 2298, including ophiuroids, Ophiotrhix sp., and crustaceans, shrimps, Periclimenaeus sp. and abundant crabs, Orthochela sp.

Etymology.

The specific epithet is from Latin, mutablilis, changeable, in allusion to the change in color after collecting.

Discussion.

Eugorgia mutabilis belongs to the daniana-group with a characteristic flabellate colony composed of flat pinnate fronds, and irregular pinnate-branching pattern, and prominent polyp mounds. The white color of the colony and sclerites of Eugorgia mutabilis separates it from the rest of the group. However, the new species is similar to Eugorgia daniana in some features, e.g. maximum number of branches, branchlet distance, polyp distribution (see Table 1), but the sclerite composition is very different. The dominant sclerites in Eugorgia mutabilis have very sharp crested discs that are very consistent in all specimens revised from Mexico, Costa Rica and Panama, and along the depth range. These type of sclerites are distinct also from the ones in Eugorgia beebei , and in Eugorgia siedenburgae .

Distribution.

Records from Costa Rica, México and Panamá suggest a wide distribution, at least from Mexico to Panamá, but this has to be further explored. The deepest record in Panama is 35 m, in Costa Rica 25 m, and in Mexico 50 m. Thus, the occurrence of this species from 11 to 50 m deep also suggests a large bathymetric range of distribution.