Eugorgia wilkiei, Olvera & Hernández & Sánchez & Gómez-Gutiérrez, 2018

Olvera, Ursula, Hernández, Osvaldo, Sánchez, Carlos & Gómez-Gutiérrez, Jaime, 2018, Two new endemic species of Gorgoniidae (Cnidaria, Anthozoa, Octocorallia) from Revillagigedo Archipelago, Mexico, Zootaxa 4442 (4), pp. 523-538 : 525-530

Eugorgia wilkiei sp. nov.

( Figs. 1–3 )

Holotype: USNM-1422107, dried specimen, El Cañón (19°17'52.0980" N, -110°48'16.9158" W), San Benedicto, Revillagigedo Archipelago, 55 m depth, January 20, 2000.

Paratypes: USNM-1422110 dried specimen, El Boiler (19°19'48.5898" N, -110°48'50.1474" W), San Benedicto, Revillagigedo Archipelago, 38 m depth, January 20, 2000; USNM-1422108, El Cañón, San Benedicto, Revillagigedo Archipelago, 55 m depth, January 20, 2000; USNM-1422109, dried specimen, El Cañón, San Benedicto, Revillagigedo Archipelago, 55 m depth, January 20, 2000.

Holotype colony: Yellow colony 35.3 cm tall, and 32.4 cm wide, profusely branched, growing in several planes (miltiplanar flabelliform) ( Fig. 1A,D , Table 1). Main branches are compressed, branching irregularly pinnate. Main stem 1.9 cm diameter, 3.7 cm long, and slightly compressed. Morphology of the holdfast is unknown because it was removed during collection. The main stem is subdivided in two branches of 1.3 cm in diameter, emerging at angles of 44°–47° and producing three secondary branches resulting in thin (1–2 mm), short (1–9 mm) and closer (0.6–2.5 mm) branchlets showing a densely branched colony ( Fig. 1A ). Branching up to 13 times. The polyps are white and fully retractable in bilabiate mounds reaching up to 0.4 mm. These are arranged in multiple irregular bands at the branchlets ( Fig. 1C ) and more sparsely over the thick branches where they are observed in parallel rows on either side of the longitudinal grooves.

Holotype sclerites: The color of the sclerites is yellow ( Fig. 1B ). All types of sclerites found in Eugorgia wilkiei sp. nov. are shown in Fig. 2A–G , Table 1. The most abundant coenenchymal sclerites are incomplete double discs, followed by capstans and spindles. However, the complete double disc, spindly capstans, bent spindles, and crosses are present too. The biometry of sclerites for each type are: complete double disc (0.057 mm – 0.040 mm), incomplete double disc (0.077 mm – 0.047 mm), capstans (0.084 mm – 0.056 mm), spindly capstans (0.054 mm – 0.032 mm), crosses (0.092 mm – 0.057 mm), spindles (0.151 mm – 0.072 mm), and bent spindles (0.136 mm – 0.076 mm), with 3–5 whorls of warty tubercles ( Table 1). No anthocodial sclerites were found.

Variability. The paratypes of Eugorgia wilkiei sp. nov. deposited in the United States Natural Museum include three complete colonies from 21–35 cm tall to 9–32 cm wide. They have the same general morphology described for the holotype. However, in some cases, the growth occurs only in multiples planes ( Fig. 3A, D ). Samples have short branches ( Fig. 3C ) and densely branched up to 10 to 13 times within complete colonies. Colony and sclerite color is uniform, bright yellow or dark red ( Fig. 3A–B ).

Remarks. Eugorgia wilkiei sp. nov. and the species Eugorgia rubens Verrill, 1868 , Eugorgia siedenburgae Breedy and Guzman, 2013 , Eugorgia beebei Breedy, Williams and Guzman, 2013 (previously proposed as monospecific groups) and daniana group (including 4 species) have branching irregularly pinnate, prominent polyp-mounds and the incomplete double discs as the more abundant type of coenenchymal sclerites ( Table 1). However, E. wilkiei sp. nov. is included in the daniana group because it branches between 10 and 13 times, has flabellate growth, and polyps are arranged in irregular rows ( Table 1). The four species included for daniana group are Eugorgia aurantiaca ( Horn, 1860) , Eugorgia daniana Verrill, 1868 , Eugorgia mutabilis Breedy, Williams and Guzman, 2013 and Eugorgia multifida Verrill, 1870 .

The branching division in the daniana group are up to 7 times (except E. aurantiaca with branching up to 6 times), and the length of the terminal twigs between 0.8–1.5 cm; nevertheless, E. wilkiei sp. nov. branches up to 13 times and the terminal twigs to 0.1–0.3 cm in length makes the colonies look densely branching.

The color of the colonies in the daniana group is specific for each of the four species: E. aurantiaca have dark orange or red colonies with a contrasting yellow longitudinal groove, E. daniana possess bright red colonies with polyp-mounds amidst for yellow spots ( Breedy et al. 2009a). Eugorgia mutabilis has white-pink colonies, and E. multifida have dark orange to bright red colonies with polyp-mound surrounded by bright yellow sclerites ( Table 1). In contrast, Eugorgia wilkiei sp. nov. has two chromotypes with a solid color (yellow or red), the sclerites have the same color than the colonies, and never with a ring or spots in the polyp-mouth.

Eugorgia wilkiei sp. nov. is distinguished by its considerably dense flabellate growth, maximum branching up to 13 times, branches arise closer, the colony growth at several multiple planes and the yellow coloration of the colonies and their sclerites (the red chromotype is similar to E. aurantica and E. multifida ). Its taxonomic features described here, suggest E. wilkiei sp. nov. is closely related to E. multifida with similar branch diameters and colony growth pattern. However, E. multifida has anthocodial rods that are absent in E. wilkiei sp. nov. ( Table 1).

Habitat. Colonies were collected from 10–65 m depth attached to volcanic rocks (but more frequently observed between 50–100 m depth from the submersible DEEPSEE) on surfaces exposed or into crevices and holes. The yellow chromotype of Eugorgia wilkiei sp. nov. is common at 10–30 m depth, and the red chromotype (which is relatively more abundant in the population) is common at 20–100 m depth. Qualitative observations indicate that E. wilkiei sp. nov. colonies are present in low density (0.2 colonies/ 100 m 2) at shallow water between 10–30 m, and in high density (25 colonies/ 100 m 2) at deep water between 50– 70 m.

Distribution. Eugorgia wilkiei sp. nov. is only known from Revillagigedo Archipelago (Socorro and San Benedicto Islands). Type locality: San Benedicto.

Etymology. Eugorgia wilkiei sp. nov. is named in memoriam of Donald Walter Wilkie (1931–2015), a Canadian-born who came to La Jolla in 1964 to begin his 35-years career as Director of the Scripps Aquarium and Founding Director of the Stephen Birch Aquarium. His life-long goal was to educate the public about marine life and ecology. A preeminent expert in his unique field as aquarium curator, educator, and ichthyologist, he cherished the collaborative scholarship program, the “Sea of Cortez Fellowship” along with the Universidad Autónoma de Baja California Sur in La Paz, Mexico to support brilliant marine biology students in the 1980’s and 1990’s. This Sea of Cortez Fellowship program promoted the formation of a new research group named Reef Fauna Project (“Proyecto Fauna Arrecifal” in Spanish) at UABCS since the 1990’s.

Figures

FIGURE 1. Eugorgia wilkiei sp. nov., holotype USNM-1422107: A, entire yellow colony; B, yellow sclerites; C, detail of the branches and calyces; D, in situ alive multiplanar colony.

FIGURE 2. Eugorgia wilkiei sp. nov., holotype USNM-1422107, MEB coenenchymal sclerites: A, spindles; B, spindles bent; C, capstans; D, incomplete double disc; E, spindly capstan; F, complete double disc; G, cross.

FIGURE 3. Eugorgia wilkiei sp. nov., paratype USNM-1422108: A, entire red colony; B, red sclerites; C, detail of the branches and calyces; D, in situ alive simple planar colony.