Anatomy and Taxonomy ofThree Species ofSea Anemones (Cnidaria: Anthozoa: Actiniidae) from the Gulfof California, Including Isoaulactinia hespervolita Daly, n. Sp.l Marymegan Daly2 Abstract: Specimens of actiniarians from the Gulf of California having a col­ umn densely covered with vesicles or verrucae have been attributed to one of three species: Anthopleura dowii, Bunodactis mexicana, or Bunodosoma californica. These three species are difficult to distinguish and are at least partly synony­ mous: Bunodosoma californica is a pro parte synonym of A. dowii and Bunodactis mexicana is a junior synonym of A. dowii. However, based on anatomy, color­ ation patterns, types of cnidae in the column, and habitat preferences, I discern three distinct species. I describe specimens attributed to Bunodaetis mexicana not belonging to A. dowii as Isoaulactinia hespervolita, n. sp. I redescribe Bunodosoma californica and A. dowii and designate a lectotype for Bunodosoma californica to resolve taxonomic confusion. ALTHOUGH MEMBERS of the family Actini­ The actiniarian fauna of the Gulf of Cali­ idae are among the most common and best fornia includes three members of Actiniidae known sea anemones, distinguishing genera that are easily confused: Anthopleura dowii and species of actiniids is difficult because of Verrill, 1869; Bunodactis mexicana Carlgren, the mosaic of traits that diagnose each genus 1951; and Bunodosoma californica Carlgren, (e.g., Carlgren 1921, 1949, Hand 1955, Dunn 1951. Members of these species are similar in et al. 1980, England 1987, den Hartog 1987). size and in tentacle number, and all have stout Characters of primary importance in separat­ columns covered with hollow, vesicular out­ ing genera within Actiniidae, such as verrucae growths. An investigation of the type speci­ and acrorhagi (e.g., Carlgren, 1949) are in­ mens of these three species illustrates how distinguishable based on external morphology difficult they can be to distinguish: one of from structures such as vesicles or pseudo­ the three syntypes of Bunodosoma californica is acrorhagi (England 1987, den Hartog 1987, a member of A. dowii, and both of the type Riemann-Ziirneck and Gallardo 1990). The specimens of Bunodactis mexicana are mem­ ubiquity of actiniids also contributes to the bers of A. dowii. However, many specimens problem of identification: many species be­ identified as Bunodaetis mexicana are not longing to Actiniidae may be found at a single members ofA. dowii or ofany other described locality. actiniid; I describe them as Isoaulactinia hes­ pervolita, n. sp. To differentiate clearly be­ tween these three species, I redescribe A. I This work was supported by NSF DEB 9978106 (Partnerships in Enhancing Expertise in Taxonomy grant dowii and Bunodosoma californica, select a to D. G. Fautin). Manuscript accepted 18 June 2003. lectotype from among the syntypes of Buno­ 2 Department of Ecology and Evolutionary Biology, dosoma californica, and provide differential di­ University of Kansas, and Division of Invertebrate Zool­ agnoses that use features visible in the field ogy, University of Kansas Museum of Natural History and Biodiversity Research Center, Haworth Hall, 1200 and after preservation. Sunnyside Avenue, Lawrence, Kansas 66045 (phone, 785-864-4607; fax, 785-864-5321; e-mail, dalym@ku. edu). MATERIALS AND METHODS I examined live specimens in the field, freshly Pacific Science (2004), vol. 58, no. 3:377-390 preserved material, and preserved museum © 2004 by University of Hawai'i Press specimens. I collected living specimens of A. All rights reserved dowii and 1. hespervolita, n. sp., from the Gulf 377 378 PACIFIC SCIENCE· July 2004 FIGURE I. Histology of Anthopleura dowii Verrill, 1869. A. Section through a columnar verruca. Verruca fixed with shell debris attached; note mucus at apex, compare with Figure 2A. Scale = 50 /-lm. B. Oral surface ofan inner tentacle, showing opaque markings typical of the species. Markings are visible in live and recently preserved specimens, but fade in ethanol over time. Scale = 5 mm. C. Section through marginal sphincter. Scale = 50 /-lm. D. Cross section through mesenteries, proximal to the actinopharynx. Pennon of parietobasilar muscle (P) a broad flap, well differentiated from the mesenterial lamella. Parietobasilar and rettactor muscles strong, restricted, with no visible muscle folds between them. Scale = 150 /-lm. of California near La Paz, Baja California versity of Kansas Natural History Museum Sur, Mexico, and specimens of A. dowii and (KUNHM). Additional material was obtained Bunodosoma califlrnica from the Pacific Ocean through the California Academy of Sciences near Todos Santos, Baja California Sur, (CAS), U.S. National Museum of Natural Mexico. Specimens were allowed to expand, History (USNM), and Yale University Peabody anesthetized in 3.5% MgS04 , and fixed in Museum (YPM). 10% buffered seawater Formalin. All freshly Measurements of pedal disk width and collected specimens were transferred to 70% column height were made on preserved ethanol after approximately 2 weeks; these material; for irregularly shaped specimens, specimens have been deposited at the Uni- greatest pedal disk width and greatest col- Sea Anemones of the Gulf of California . Daly 379 FIGURE 2. Histology of Isoaulactinia hespervolita, n. sp. A. Section through a columnar verruca. Area between arrows indicates specialized region: note bilayered appearance of ectoderm near the junction with the mesoglea, and thin, densely packed epitheliomuscular cells in the ectoderm. Compare with Figures lA, 3A. Scale = 50 l-lm. B. Section through margin showing sphincter. At the margin (M), each endocoel and exocoel terminates in a single verruca (V) that does not contain holotrichs. Because the margin is flat rather than denticulate, the fosse (F) is shallower than in A. dowii or Bunodosoma californica. Scale = 50 l-lm. C. Cross section through mesenteries, proximal to the actinopharynx. Pennon of the parietobasilar muscle (P) is not very broad. Note accessory muscles (arrow) between parietobasilar and retractor muscles. Scale = 500 l-lm. umn height were recorded. Longitudinal and ing the geographic and size variation of the transverse serial sections 6-10 Ilm thick were specimens examined. For each tissue sample, made from specimens dehydrated in ethanol I searched for the largest and smallest cnidae and embedded in Paraplast. Sections were of a particular type (Hand 1955, England stained in Heidenhain's Azan (Presnell and 1987). Nomenclature of cnidae follows Mar­ Schreibman 1997). iscal (1974). 2 Small pieces (approximately 1 mm ) of tentacle, column, marginal spherule, limbus, Verrucae and Vesicles actinopharynx, and mesenterial filament tis­ sue were squashed on a slide and examined This trio of species provides an excellent at I,OOOx using differential interference mi­ opportunity to explore the differences be­ croscopy; length and width of undischarged tween columnar vesicles and verrucae. The cnidae were measured using ScanPro mea­ primary distinction between the genus An­ surement software (Jandel Scientific Software thopleura and the genus Bunodosoma is based 1995) and a Summa Sketch digitizing tablet on the nature of the hollow columnar out­ (Summagraphics). For each species, cnidae growths: in Anthopleura, these structures are were measured from specimens represent- cup-shaped, adhesive, and are called verrucae; 380 PACIFIC SCIENCE· July 2004 FIGURE 3. Histology of Bunodosoma californica Carigren, 1951. A. Section through a columnar vesicle. Note thickness ofmesoglea at apex, mucous gland cells (arrow), and similarity of ectoderm on apex and sides ofvesicle; compare with Figures lA, 2A. Scale = 50 J.Im. B. Section through marginal sphincter (KUNHM 1619). Scale = 50 J.Im. C. Section through the marginal sphincter muscle of a highly contracted specimen (CAS 95945); compare with Figure 3B. Scale = 100 J.Im. D. Section through mesenteries proximal to the actinopharynx. Parietobasilar muscle weak, with very smaIl pennon (P). Scale = 150 J.Im. in Bunodosoma, the structures are rounded, relatively thin, unmuscular endoderm (Fig­ typically nonadhesive, and are called vesicles. ures lA, 2A) (Stephenson 1928, den Hartog Isoaulactinia is also characterized as having 1987, Riemann-Ziirneck and Gallardo 1990). cup-shaped, adhesive verrucae. Distinguish­ The columnar evaginations of members of ing between verrucae and vesicles is not triv­ Bunodosoma are typically nonadhesive or ial in practice, especially when dealing with only weakly adhesive (e.g., Verrill 1899, Ste­ preserved specimens: verrucae may drop their phenson 1918, 1928, Carlgren 1921, 1928, attached shells and debris during preservation 1938, den Hartog 1987) and mayor may not or collection, and rounded vesicles may be­ have nematocysts (e.g., Carlgren 1921, 1928, come deflated and resemble verrucae. 1938, den Hartog 1987). Verrucae are well defined anatomically: a Because of its variability among species verruca is an adhesive, hollow evagination of of Bunodosoma, the morphology of a vesicle all three layers of the column wall, with thick, needs to be described in more detail than that glandular ectoderm that lacks nematocysts, of a verruca. In Bunodosoma califo17zica (Figure relatively thin mesoglea (especially at the 3A), the vesicles are nonadhesive: I observed center, where it may form a cinclis), and no material adhering to them in the field nor Sea Anemones of the Gulf of California . Daly 381 do any of the museum specimens I examined varies: in live specimens of