Epizoanthus giveni, Philipp, Nicholas A. & Fautin, Daphne G., 2009

Philipp, Nicholas A. & Fautin, Daphne G., 2009, Three new species of shallow water, yellow zoanthids (Hexacorallia: Zoanthidea: Epizoanthidae) from southern California, USA, and southern Australia, Zootaxa 2058, pp. 53-61 : 54-58

Epizoanthus giveni new species

Figures 1A , 2 A

Material examined. North-eastern Pacific Ocean, USA, California, Los Angeles County, Santa Catalina Island, Two Harbors, west end of Ship Rock (33º27’N, 118º29’W), 62 ft (19 m), collected by Adam Daw, 13 December 2006; SBMNH 423117, Syntypes, 3 pieces of 23, 17, and 24 polyps each; KUDIZ 0 0 2985, Syntypes, 3 pieces of 38, 10, and 27 polyps each. Same locality and depth, collected by Adam Daw, 10 November 2006; SBMNH 423118, Syntypes, 6 pieces of 15, 14, 13, 9, 22, and 5 polyps each; USNM 1116110, Syntypes, 4 pieces of 14, 9, 11, and 18 polyps each.

Colony morphology and color. In life, vivid yellow (Adam Daw, pers. comm.; Figure 1A ; Gotshall 2005: fig. 70); in preservative, light-brown/tan. Polyps spaced as much as a polyp diameter apart, smaller ones interspersed among larger ones; some flush with surface of coenenchyme but most protrude.

External anatomy. In preserved specimens, contracted polyps protrude no more than 8 mm from thin (0.5–1.5 mm thick) coenenchyme; 2–5 mm diameter when contracted. Ectoderm and outer mesoglea densely encrusted with sand, contributing to the polyps’ color. Scapus ridges obvious in closed polyps, increase in number with size of polyp to maximum of 19.

Internal anatomy. Marginal sphincter muscle alveolar; alveoli situated in middle of mesoglea, slightly nearer endoderm proximally and ectoderm distally; alveoli occupy no more than a quarter the width of the mesoglea, arrayed in a longitudinal column ( Figure 2 A). Mesenteries number 26 in smaller polyp (0.5 mm diameter) to 36 in many larger polyps (5 mm in diameter). Actinopharynx uncorrugated. Siphonoglyph apparent. No zooxanthellae.

Cnidae. Cnidom spirocysts, basitrichs, holotrichs, microbasic b- mastigophores, microbasic p - mastigophores ( Figure 3 ). See Table 1 for sizes and distribution. Cnidae from the proximal and distal parts of tentacles did not differ, so measurements from them were combined.

type of nematocyst to the total number examined; n is the number of measured capsules. Measurements, in µm, are given

as a range of length x width; values in parentheses are of exceptionally large or small capsules. Letters refer to images in

Figure 3 .

Tissue Type N n Size

Tentacle spirocyst (F) 6/6 128 (9.6) 11.0–21.8 (24.2) x 2.0–4.7

basitrich (A) 6/6 92 (14.1) 16.0–26.9 (28.7) x 2.2–5.4 microbasic b -mastigophore (D) 6/6 96 (13.3) 14.4–25.7 x 2.2–5.0 TABLE 2. Differences among some species of Epizoanthus and Parazoanthus ; new species bolded. Data from original descriptions except as noted. Polyp Polyp Other Sphincter muscle location length diameter Mesenteries Scapus ridges Color Distribution distinguishing and morphology (mm) (mm) features

giveni n. sp. Mesoglea: alveolar, 8 or less 2 to 5 26 to 36 to 19, number vivid yellow (fig. Islets off Southern alveoli arrayed increases with 1A) Channel Islands longitudinally polyp size California, USA

californicum Mesoglea : strong with 9 or less 3 to 4 34 to 38 none yellowish-brown Gulf of California,

Carlgren, 1951 meshes drawn out Mexico transversely

gabrieli Mesoglea : strong, broad, 8 or less 3.5 or to 30 distinct unknown Gulf of California,

Carlgren, 1951 transversely stratified less Mexico

induratum Mesoglea : scattered 1 to 5 1.5 to 4 to 38 to 22 pale salmon Corona del Mar, weakly

Cutress & alveoli of various sizes California bioluminescent

Pequegnat, 1960

leptoderma Mesoglea : broad alveoli 5 to 20 1.5 to 5 to 36 to 18 tan Corona del Mar,

Cutress & nearer endoderm than California

Pequegnat, 1960 ectoderm

scotinus Wood, Mesoglea : strong, 70 or 10 to 30 40 to 70 unknown reddish-brown to Northern Channel transversely stratified, less light yellow, mouth Islands of fills width of mesoglea brighter orange California to most of length, against (fig. 1B) (data also Puget Sound, ectoderm proximally from Gotshall Washington 2005) ( Gotshall 2005)

karenae n. sp. Mesoglea: alveoli broad, 12 or 2 to 5 36 to 40 distinct, 20, in vivid yellow with South Australia may occur unstratified and filling less small and large radiating dark- and New Zealand among most of margin distally, polyps orange lines on sponges (fig. stratified proximally oral disc 1C; Gowlett- Holmes 2008)

rodmani n. sp. Mesoglea: alveoli 8 or less 3 to 4.5 42 to 48 none obvious vivid yellow Southern elongate, situated in Australia middle of mesoglea

sabulosum Mesoglea: alveoli few, 4 or less 3 or less to 30 to 15 unknown Southern epizoic with

Cutress, 1971 scattered, in center of Australia sponges; mesoglea distally, nearer contains ectoderm proximally zooxanthellae

axinellae Endoderm : diffuse and 2 to 15 2 to 5 28 - 39 14 to 18 pale yellow to Mediterranean, epizoic with Schmidt, 1862) long orange; deeper northeastern sponges and data from color around Atlantic other animals Herberts 1972, mouth such as Manuel 1981) gogonians,

worm tubes,

and shells elongatus Endoderm : very weak, 15 to 20 3 to 4 28 to 32 to 15 unknown Calbuco, Chile epizoic with McMurrich, 1904 almost unbranched, with hydroids

scattered mesogleal

processes

Natural history, geography. The specimens of Epizoanthus giveni n. sp. we studied had been attached to a rock wall at 19 m. At present this species is known only from small islets off the southern Channel Islands of Santa Catalina and San Clemente.

Etymology. Epizoanthus giveni n. sp. is named in honor of Dr. Robert R. Given, who worked at the University of Southern California Wrigley Marine Science Center, and played a major role in establishing the Catalina Island Conservancy, which has served to preserve the natural environment of the island for more than 40 years. Dr. Given, like many other biologists and collectors, pointed out the need for this species to be named.

Differential diagnosis. See Table 2, which compares features of all three new species with those of some sympatric and externally similar species. Additionally, in the Channel Islands of California, E pizoanthus giveni n. sp. occurs in the same habitat as two other species of Epizoanthus , E. leptoderma Cutress and Pequegnat, 1960 , and E. induratum Cutress and Pequegnat, 1960 . Epizoanthus induratum occurs at greater depths than E. giveni n. sp. and is weakly bioluminescent ( Cutress & Pequegnat 1960). Three species of zoanthids are illustrated in the field guide by Gotshall (2005: 34): two are referred to as “Yellow Zoanthids”— Parazoanthus lucificum Cutress and Pequegnat, 1960 , which is attached to gorgonians, and E. scotinus , depicted in our Fig. 1 B—and E. giveni n. sp., which is labeled “ZOANTHID (undescribed species).”

In comparison to E. giveni n. sp., E. leptoderma contains smaller spirocysts and microbasic b - mastigophores of the tentacles, and also has microbasic b -mastigophores in the actinopharynx; E. induratum contains holotrichs in the tentacles and microbasic b -mastigophores in the actinopharynx; E. scotinus has holotrichs in the tentacles, much larger spirocysts, microbasic p -mastigophores in the actinopharynx, and atrichous isorhizas in the ectoderm. Atrichous isorhizas are not known in zoanthids at the small sizes reported by Wood (1957) (Ryland & Lancaster 2004). It is possible that the capsules measured were small holotrichs, which were once referred to as atrichous isorhizas ( Cutress 1955). According to Bigger (1982), the two are difficult to distinguish with a light microscope and the nematocysts should be considered holotrichs. Two other similar species are E. californicum Carlgren, 1951 , and E. gabrieli Carlgren, 1951 . In comparison to E. giveni n. sp. E. californicum has holotrichs in the tentacles and microbasic b -mastigophores in the actinopharynx; E. gabrieli has smaller microbasic b -mastigophores in the tentacles and only holotrichs of the small variety were measured.

Figures

FIGURE 2. Longitudinal sections through alveolar marginal sphincter muscles of new species of Epizoanthus. A. Epizoanthus giveni n. sp. Alveoli nearly circular in cross section, arrayed in single column, separate from one another, decrease in diameter proximally. B. Epizoanthus karenae n. sp. Alveoli not stratified and fill most of margin distally, transversely stratified and near endoderm proximally. C. Epizoanthus rodmani n. sp. Alveoli elongate in cross section, located nearer ectoderm distally, near endoderm proximally. Scale bar = 200 µm.

FIGURE 3. Cnidae. Scale bar = 20 µm; refer to Tables 1 and 3 for occurrences and size ranges. A. Basitrich. B. Basitrich. C. Microbasic p - mastigophore. D. Microbasic b - mastigophore. E. Holotrich. F. Spirocyst. G. Holotrich.

FIGURE 1. A. Epizoanthus giveni n. sp. in life, attached to a rock wall. Note vivid yellow color and polyps of various sizes. Photograph by Daniel W. Gotshall, with permission. B. Epizoanthus scotinus in life. Note wider oral disc and paler column, tentacles, and oral disc as compared to E. giveni n. sp. Photograph by Daniel W. Gotshall, with permission. C. Epizoanthus karenae n. sp. in life. Note radiating dark-orange lines on oral disc. Photograph by Karen Gowlett-Holmes, with permission. D. Epizoanthus rodmani n. sp. in life. Note lack of radiating lines on oral disc. Photograph by Karen Gowlett-Holmes, with permission. Scale bars = 2 cm; scale was determined in consultation with the photographers.