Sagartiogeton californicus (Carlgren, 1940)

Fautin, D. G., 2012, Taxonomy and distribution of sea anemones (Cnidaria: Actiniaria and Corallimorpharia) from deep water of the northeastern Pacific, Zootaxa 3375, pp. 1-80 : 43-48

Sagartiogeton californicus (Carlgren, 1940)

( Figures 34 –37, Table 5, Appendix 15)

Synonyms: see below

Body form and size. Column ectoderm tan or rose; in most specimens ectoderm sloughed off (likely caused by collection process), exposing mesoglea. Mesoglea of scapulus white, thick (about 1 mm), and cartilaginous; that of scapus thin, and mesenterial insertions and purple endoderm of mesenteries (white in two specimens) apparent. Gametogenic tissue white, and filaments tan to purple. Purple endoderm and white gametogenic tissue make column appear purple and white spotted when ectoderm sloughed off ( Figure 34). Sparse cinclides in distal part of scapus and near limbus.

Specimens short (about 3 mm long near mouth, 0.1 mm long at limbus) to approximately as tall as wide (to about 20 mm long), depending on contraction. Pedal disc typically wide; oral disc small and typically hidden along with bases of tentacles below contracted margin of column. Pedal disc circular or slightly oval, to diameter of 47 mm. Oral disc (to about 14 mm diameter) much smaller than pedal disc.

Pedal disc. Pedal disc off-white to tan; in most specimens slightly transparent with mesenterial insertions visible. Wide, concave in most specimens, shape depending on substrate; attached to shells, rocks, or crab

Oral disc and tentacles. Oral disc tan and smooth, mesenterial insertions may be visible. Approximately same shape as pedal disc (circular or slightly oval). In most specimens margin contracted so oral disc and bases of inner tentacles not visible.

Mouth approximately half oral disc diameter. Lips purple, slightly raised, radially furrowed. Position of two symmetrical siphonoglyphs evident externally by smaller lips and slightly lighter pigmentation.

About 200 dark purple to white tentacles; ectoderm of outer tentacles typically sloughed away, dark purple endoderm visible through transparent mesoglea. Conical; 1–8 mm long, taper from 0.3–1 mm at base to less than 0.1 mm at tip. Tentacles arrayed in six cycles near margin (fewer tentacles in small specimens). Exocoelic tentacles outermost; shorter than inner (endocoelic) tentacles.

Internal anatomy. Actinopharynx dark purple; long in tall specimens, short in flat specimens. Each of two off-white siphonoglyphs attached to pair of directive mesenteries.

Mesenteries typically with purple endoderm (pink to white in some specimens). Arrayed in five cycles; smaller specimens with fewer cycles (three cycles in flat specimen with pedal disc diameter 8 mm). All mesenteries, except some of youngest cycle, with filaments and gametogenic tissue. Mesenteries of first three cycles complete, with central stomata (see Arellano & Fautin 2001). Mesenteries develop from proximal and distal end. Acontia salmon or off-white with small purple spots. Retractor muscles diffuse, may be lobed; poorly developed in young mesenteries, well developed in old mesenteries ( Figure 35a). Parietobasilar muscles not apparent.

Mesogleal marginal sphincter muscle reticular, well developed, occupies most of mesoglea; separated from endoderm by thin strip of mesoglea ( Figure 35b). Longitudinal musculature of tentacles ectodermal; circular muscles inferred to be endodermal ( Figure 35c).

Cnidae. Gracile and robust spirocysts, basitrichs, microbasic p -mastigophores, microbasic amastigophores. Large macrobasic mastigophores (likely macrobasic p -mastigophores) were found in clusters in the mesenterial filaments of only one specimen of S. californicus ; because discharged nematocysts were not observed, we are unable to determine for certain if they are macrobasic amastigophores or p -mastigophores. Sizes and distribution of cnidae given in Table 5; cnidae illustrated in Figure 36.

Distribution. Sagartiogeton californicus occur from the northeastern Pacific from Mexico to British Columbia from depths of 73 m to at least 1,463 m (Figure 37).

Taxonomic remarks. The original description of Actinothoë californica Carlgren, 1940 , lacks an illustration of the whole animal and many anatomical details. We were unable to locate specimens upon which Carlgren (1942) based his description in any of the natural history museums that (to our knowledge) have material Carlgren studied; therefore, we designate specimen KUIZ 001451, collected 26-Oct-1997 at 34.89– 34.91° N, 122.50– 122.49° W, 687 m, as the name-bearing neotype of S. californicus . Article 75 of the International Code of Zoological Nomenclature (International Commission on Zoological Nomenclature 1999) stipulates that a neotype is to be designated only if “a name-bearing type is necessary to define the nominal taxon objectively … not as an end in itself, or as a matter of curatorial routine.”

The misidentification of specimen USNM 53337 by Cutress as Sagartiogeton californicus (below) illustrates the need to designate a neotype to anchor the species concept. The specimen that we designate as the neotype of Sagartiogeton californicus, KUIZ 001451, was collected nearest the type locality (27° 04’ N, 111° 54’ W, 40 fm) of those animals we examined.

Specimen USNM 53337 differs from the specimens we examined in having a very long, lumpy scapulus with deep longitudinal furrows. It is larger (24 mm long, pedal disc 44 mm wide), and the older mesenteries are less muscular and more lobed than in the specimens Carlgren (1940) described and those we examined. The specimen lacks small basitrichs in the tentacles and possesses two sizes of microbasic amastigophores in the acontia, the smallest approximately 27 µm long. This specimen is clearly a member of family Sagartiidae , but not Sagartiogeton californicus .

Carlgren (1949) and Kostina (1988) included both Actinothoe californica and Sagartiogeton californica in their inventories, seemingly considering them as separate species; both cited Carlgren (1940) as the author of both species, but Carlgren (1940) described only one species belonging to family Sagartiidae .

All of the specimens we examined that are cited in Appendix 15 agree well with published details except that Carlgren (1940) did not find small basitrichs in all tissues. These small nematocysts were sparse and easy to miss in specimens we examined. In addition, Carlgren (1940) reported much smaller microbasic amastigophores and basitrichs of the acontia than we found; however, size of these cnidae in acontia of members of Sagartiogeton , the genus into which Carlgren (1949) placed the species, vary greatly from specimen to specimen (Carlgren 1942). Due to similarities in location, depth, and morphology, we have identified as S. californicus the specimens that we examined. Although the external anatomy of this species varies, cnidae and internal anatomy of specimens are consistent.

The only other species of Sagartiogeton recorded from the Pacific Ocean, Sagartiogeton erythraios Zelnio, Rodriguez, and Daly, 2009 , occurs in the southwestern Pacific to depths of 2,620 m. It can be distinguished from S. californicus by cnidae differences, in having fewer mesenteries and tentacles (3 cycles of mesenteries and 48 tentacles), no cinclides, and a column with a cuticle and papillae. The combination of a reticular marginal sphincter muscle nearly as wide as the mesoglea, retractor muscles that are often lobed, and central stomata differentiate S. californicus from S. erythraios , and its other congeners, all of which occur in the northern Atlantic Ocean.

Material examined. See Appendix 15.

Differential diagnosis. Sagartiogeton californicus can be distinguished from its congeners by its combination of: column with no cuticle or papillae; about 200 tentacles; five cycles of mesenteries; central stomata; cinclides; wide reticular marginal sphincter muscle; retractor muscles that are often lobed.