Epiactis prolifera Verrill, 1869

Vassallo-Avalos, Aurora, González-Muñoz, Ricardo, Acuña, Fabián H., Cervantes-Ramírez, Itzel Ittaí & Rivas, Gerardo, 2022, Intertidal sea anemones (Cnidaria: Actiniaria) from the west coast of the Peninsula of Baja California, Mexico, Zootaxa 5165 (2), pp. 151-179 : 168-169

Epiactis prolifera Verrill, 1869

( Figure 6 , Table 6 )

Bunodes japonica Verrill, 1869 (1870) , p. 62 [28]

Epiactis fertilis Andres, 1883, p. 570 , 574–575

Epiactis prolifera Verrill, 1869, p. 492 –493 [original description]

Epiactis ritteri Torrey, 1902, p. 393 –394

[non] Epiactis prolifera Uchida, 1934, p. 17 –31

Material examined. (See Appendix 1).

Short description.

External anatomy: oral disc smooth, flat, reddish to cherry, or olive-green, with whitish radial lines; mouth rounded. Tentacles shorter than oral disc, smooth, thin, tips blunt, reddish to cherry or olive-green, base whitish to gray; tentacles arranged in five cycles (up to 72 tentacles in specimens examined), all of similar length ( Figure 6A–B ). Deep fosse. Column cylindrical, smooth, in preserved specimens 4–10 mm in height, 5–17 mm in diameter, with mesenterial insertions visible as light and dark alternating longitudinal rows. Pedal disc well-developed, 6–21 mm in diameter, adherent, irregular, smooth, wider than diameter of column. Column and pedal disc reddish to cherry or olive-green with white vertical lines along the column. Up to 25 broods of different sizes attached to the middle of the column, forming a kind of ring around it ( Figure 6A–D ). Preserved specimens with beige column, the most proximal part with raised folds, tentacles the same color as the column.

Internal anatomy: mesenteries arranged in four cycles: first and second perfect, others imperfect.Actinopharynx slightly sulcated with two pairs of directive mesenteries, each attached to well-developed siphonoglyph. Oocytes and spermatic cysts in the imperfect mesenteries ( Figure 6E–F ). Retractor muscles restricted to diffuse. Parietobasilar muscles well developed ( Figure 6G ); basilar muscles well developed. Endodermal marginal sphincter muscle circumscribed, palmate ( Figure 6H ). Longitudinal muscles of tentacles ectodermal ( Figure 6I ). Azooxanthellate.

Cnidom: basitrichs, spirocysts, holotrichs, and p -mastigophores A ( Figure 6J–R ). See Table 6 for the sizes and distribution of cnidae.

Natural history. Epiactis prolifera inhabits open shores in the intertidal zone attached to rocks, algae or sea grasses, in crevices or hollows. It is also found in the subtidal, some individuals have been extracted from 5 to 27 m ( Hand 1955).

Distribution. Along the North American Pacific coast in Washington, Oregon and California ( Verrill 1869; Carlgren 1949, 1951; Hand 1955; Dunn 1975; Fautin & Chia 1986; Larson & Daly 2015, 2016). This is the first record for Mexico.

Remarks. Currently 19 species of the genus Epiactis are known ( Daly & Fautin 2022b) of which five are distributed in the North Pacific and have external brooding: E. japonica ( Verrill 1869) , E. lisbethae Fautin & Chia, 1986 , E. prolifera , E. ritteri Torrey, 1902 ( Larson & Daly 2016) and E. irregularis Carlgren, 1951 . Epiactis ritteri is distinguished from E. prolifera by the flattened limbus ornamented with square-based protuberances containing holotrichs, and is monochrome in color. Likewise, characteristics of the brooding groove and the protuberances on the column distinguish E. japonica from E. prolifera ( Larson & Daly 2015) .

The sphincter of E. prolifera is restricted and palmate, unlike that of E. irregularis which is almost restricted and elongate as shown by Carlgren (1951). Although the reviewed specimens agree with E. irregularis in the absence of holotrichs in the column, they differ in the presence of basitrichs larger than 21 µm in the column. Moreover, spirocysts and holotrichs are not reported in the tentacles of E. irregularis , unlike E. prolifera . We did not observe basitrichs larger than 38 µm in the filaments, in contrast to the report by Carlgren (1951). The specimen that Carlgren (1951) observed was sterile, so the sex allocation and brood location in E. irregularis cannot be known.

Epiactis lisbethae resembles E. prolifera in the coloration of the column and the sizes and distribution of the cnidae. However, E. prolifera adheres no more than 40 young, generally of different sizes, which reflects a continuous reproduction, unlike E. lisbethae that can adhere several hundred young, generally of the same size, with seasonal reproduction ( Fautin & Chia 1986). In addition, E. prolifera is a gynodioecious hermaphrodite while E. lisbethae is gonochoric ( Dunn 1975; Fautin & Chia 1986). The populations of E. prolifera consist of females and hermaphrodites but not males and not all individuals exhibit hermaphroditism ( Dunn, 1975). The reproductive characteristsics of our specimens are the same as has been reported for E. prolifera and unlike E. lisbethae : we found hermaphroditic specimens and observed spermatogenic and oogenic tissue in the same mesentery, as did Dunn (1975) for E. prolifera . Although Fautin & Chia (1986) indicate that E. prolifera lacks longitudinal column stripes, our specimens have vertical white stripes on its column, which agrees with Hand´s (1955) report.

The cnidom we report agree with those previously reported ( Carlgren 1952; Hand 1955; Fautin & Chia 1986) except for the holotrichs in the column which were not found in our specimens. Hand (1955) also did not report holotrichs in the column. This absence could be related to antagonistic behaviors where these cnidae may or may not appear according to the interactions of the species ( Dunn et al. 1980).

Figures

FIGURE 6. Epiactis prolifera. A–B) oral view showing tentacles and column. C–D) detail of juveniles around the column of different sizes. E–F) cross section of column showing gametogenic tissue. G) cross section of column showing the retractor and parietobasilar muscles. H) longitudinal section of the distal column showing marginal sphincter muscle. I) longitudinal section of tentacle showing ectodermal muscles. (J–R) Cnidae. tentacles: (J) basitrich I, (K) basitrich II, (L) spirocyst, (M) holotrich; actinopharynx: (N) basitrich, (O) p-mastigophores A; column: (P) basitrich; filaments: (Q) basitrich, (R) p-mastigophores A. Abbreviations. ep: epidermis, g: gastrodermis, juv: juveniles, lm: longitudinal muscles, me: mesoglea, o: oocyte, pbm: parietobasilar muscles, rm: retractor muscles, sc: sperm cysts, sp: sphincter, t: tentacles. Scale bars: A–D: 15 mm; E–F–I: 200 µm, G–H: 500 µm; J–R: 20 µm.