Epizoanthus rodmani, 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 : 60

Epizoanthus rodmani new species

Figures 1 D, 2C

Material examined. Pacific Ocean, Australia, Tasmania, Port Davey, Bathurst Channel, off Joan Point, ~ 43° 20’S, 146° 04’E, 5–21 m, collected by K.L. Gowlett-Holmes, 5 April 1993; SAM H1603, Holotype, 22 polyps. Pacific Ocean, Australia, South Australia, Kangaroo Island, W of Western River Cove, Pissy Boy Rock, “The Amphitheater”, ~ 35° 40’S, 136°58’E, 7–9 m, collected by K.L. Gowlett-Holmes, 9 March 2002; KUDIZ 0 0 2984, Paratypes, 2 pieces (unknown whether from a single colony) of 6 and 18 polyps.

Colony morphology and color. In life, vivid yellow ( Figure 1 D) (Karen L. Gowlett-Holmes, CSIRO, Hobart, pers. comm.). In preservative, yellow/light brown. Three pieces examined had 7–22 polyps each. In preserved material, coenenchyme surface visible between polyps, smaller polyps interspersed among larger ones; all protrude from surface of coenenchyme.

External anatomy. In preserved specimens, contracted polyps protrude no more than 8 mm from thin (1 mm thick) coenenchyme; 3–4.5 mm in diameter when contracted. Ectoderm densely encrusted with dark sand and quartz contributing to polyps’ dark color. Scapus ridges not obvious in closed polyps.

Internal anatomy. Marginal sphincter muscle alveolar, situated in middle of mesoglea, nearer ectoderm distally, nearer endoderm proximally ( Figure 2 C), alveoli elongate, more elliptical than circular in section. Mesenteries 42 in polyp 3 mm in diameter to 48 in polyp 4.5 mm in diameter. Actinopharynx longitudinally corrugated. Siphonoglyph apparent. No zooxanthellae.

Cnidae. Cnidom spirocysts, basitrichs, holotrichs, microbasic b- mastigophores, microbasic p - mastigophores ( Figure 3 ). See Table 3 for sizes and distribution.

Natural history, geography. Specimens studied were collected from a rock wall at 5– 21 m.

Etymology. Epizoanthus rodmani n. sp. is named in honor of Dr. James E. Rodman, who helped taxonomy in all fields as Director in the Division of Environmental Biology of the US National Science Foundation and especially by creating and supporting the program Partnerships for Enhancing Expertise in Taxonomy (PEET).

Differential diagnosis. See Table 2. In addition, E. karenae n. sp. has radiating dark-orange lines on the oral disc and smaller polyps surrounding larger polyps, whereas the disc of E. rodmani n. sp. lacks radiating lines and polyps of different sizes do not differ in distribution. Many of the species of Epizoanthus occurring in the western Pacific Ocean differ from E. karenae n. sp. and E. rodmani n. sp. in habitat and/or substratum. The sphincter muscle of Epizoanthus sabulosus Cutress, 1971 , which occurs in the same latitudes and depths as the new Australian species, is narrower distally than that of either E. karenae n. sp. or E. rodmani n. sp., and has fewer alveoli. Although the size and distribution of nematocysts in E. karenae n. sp. and E. rodmani n. sp. are very similar, microbasic b -mastigophores in both species are generally larger than those in E. sabulosus , and basitrichs are not known in E. sabulosus .

Two species of Parazoanthus are externally similar to all three new species. In addition to the diagnostic differences in sphincter muscle, in P. axinellae ( Schmidt, 1862) , only large (23–33 x 12–15 µm) holotrichs were measured. No nematocyst data appear to have been published for P. elongatus McMurrich, 1904 .

Now three species of Epizoanthus have been described from southern Australia, the two we describe and E. sabulosus . Gowlett-Holmes (2008) included in her guide to southern Australia five species of zoanthids, including another undescribed species of Epizoanthus . There may be others as well; an inventory of all zoanthid species present, both there and in southern California, is needed.

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.