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8 May 2024 Revision of the Genus Actinostella (Cnidaria: Actiniaria: Actinioidea) from Tropical and Subtropical Western Atlantic and Eastern Pacific: Redescriptions and Synonymies
Yamaly Barragán, Estefanía Rodríguez, Tommaso Chiodo, Luciana C. Gusmão, Carlos Sánchez, Daniel Lauretta
Author Affiliations +
FIG. 1.
Geographic distribution of species of Actinostella.

TABLE 1.
Material examined in this study. Catalogue number, locality, coordinates, depth and date of collection are provided. Abbreviations: AMNH, American Museum of Natural History; MACN, Museo Argentino de Ciencias Naturales Bernardino Rivadavia; MZUSP, Museu de Zoologia da Universidade de São Paulo; SMNH, Swedish Museum of Natural History; USNM, National Museum of Natural History; YPM, Yale Peaboy Museum; (*), data transcribed from museum label, but does not correspond with type locality.




FIG. 2.
External anatomy of Actinostella bradleyi (Verrill, 1869). A, Oral view of live semiexpanded specimen showing the marginal ruff; B, oral view of live and expanded specimen; C, lateral view of live semiexpanded specimen; notice rows of distal verrucae (v); D, lateral view of preserved specimen; E, detail of oral view of a semiexpanded preserved specimen; F, detail of the vesicles (ve) in the marginal ruff (f) of a preserved specimen. Abbreviations: f, marginal ruff; v, verrucae; ve, vesicles. Scale bars: A–F, 5 mm.

FIG. 3.
Internal anatomy of Actinostella bradleyi (Verrill, 1869). A, longitudinal section of the distal column showing distal verrucae (v), vesicles (ve) in the marginal ruff, marginal sphincter muscle (s), and the fosse; B, cross section at the actinopharynx level showing four cycles of mesenteries; numbers between pairs of mesenteries indicate the corresponding cycle; C, detail of the endodermal marginal sphincter muscle; D, cross section of a tentacle showing the ectodermal longitudinal muscles; E, detail of developing spermatic cysts (sc); F, detail of developing oocytes (o); G, detail of a cross section showing the retractor (r) and parietobasilar (p) muscles; H, cross section of proximal end showing the basilar muscles (b). Abbreviations: b, basilar muscles; ep, epidermis; ga, gastrodermis; me, mesoglea; o, oocytes; p, parietobasilar muscle; r, retractor muscle; s, sphincter; sc, spermatic cysts; t, tentacle; v, verrucae; ve, vesicles. Scale bars: A, B, G, H, 0.5 mm; C–F, 0.1 mm.

FIG. 4.
Cnidae of Actinostella bradleyi (Verrill, 1869). A, C, E, H, I, K, L, M, basitrichs; B, spirocysts; F, N, basitrichs S; D, G, J, P, p-mastigophore A; O, b-mastigophore; Q, p-mastigophore B1.

FIG. 5.
External and internal anatomy of the holotype of Asteractis bradleyi Verrill, 1869 (YPM-1009) (= Actinostella bradleyi). A, lateral view of holotype, showing the marginal ruff; B, oral view of holotype; C, detail of the pedal disc of holotype; D, longitudinal section of the distal column showing distal verrucae (v), vesicles (ve) in the marginal ruff, marginal sphincter muscle (s), and the fosse; E, detail of the endodermal marginal sphincter muscle; F, detail of the verrucae in the distal column; G, cross section at the actinopharynx level showing the directive mesenteries, retractor muscle (r), and siphonoglyphs (si); H, detail of a pair of mesenteries of the third cycle showing the parietobasilar muscle (p); I, longitudinal section of proximal end showing basilar muscles (b). Abbreviations: b, basilar muscle; f, marginal ruff; p, parietobasilar muscle; r, retractor muscle; s, sphincter; si, siphonoglyphs; v, verrucae; ve, vesicle. Scale bars: A–C, 5 mm; D–I, 0.5 mm.

FIG. 6.
Cnidae of holotype of Actinostella bradleyi (Verrill, 1869) (YPM-1009). A, C, E, H, I, K, L, M, basitrichs; B, spirocysts; F, N, basitrichs S; D, G, J, P, p-mastigophore A; O, b-mastigophore.

TABLE 2.
Size ranges and distribution of cnidae of Actinostella bradleyi (Verrill, 1869). N, Total number of capsules measured; M, Ratio of number of specimens in which each cnidae was found to number of specimens examined; F, Frequency, +++ = very common, ++ = common, + = rather common, --- = sporadic; SD, standard deviation; NF, not found. Sizes in micrometers. Letters in parenthesis correspond to images in figures 4 and 6.

FIG. 7.
External anatomy of Actinostella californica (McMurrich, 1893). A, Oral view of live semiexpanded specimen; B, lateral view of live specimen; notice row of distal verrucae (v); C, oral view of live semiexpanded specimen showing the marginal ruff (f); D, lateral view of preserved syntype USNM 1776; E, oral view of preserved syntype USNM 1776 showing the vesicles (ve). Abbreviations: f, marginal ruff; v, verrucae; ve, vesicles. Images in A and B courtesy of V. Häussermann. Scale bars: A–D, 5 mm.

FIG. 8.
Internal anatomy of Actinostella californica (McMurrich, 1893). A, longitudinal section of the distal column showing distal verrucae (v), vesicles (ve) in the marginal ruff, marginal sphincter muscle (s), and the fosse; B, cross section at the actinopharynx level showing cycles of mesenteries and siphonoglyphs (si); numbers between pairs of mesenteries indicate the corresponding cycle; C, detail of the endodermal marginal sphincter muscle; D, cross section of a tentacle showing the ectodermal longitudinal muscles; E, detail of developing oocytes (o); F, detail of a cross section showing the retractor (r) and parietobasilar (p) muscles; G, cross section of proximal end showing the basilar muscles (r). Abbreviations: b, basilar muscles; ep, epidermis; ga, gastrodermis; me, mesoglea; o, oocytes; p, parietobasilar muscle; r, retractor muscle; s, sphincter; si, siphonoglyph; t, tentacle; v, verrucae; ve, vesicles. Scale bars: A, B, F, 0.5 mm; C–E, G, 0.1 mm.

FIG. 9.
Cnidae of Actinostella californica (McMurrich, 1893). A, C, D, F, G, I, J, K, basitrichs; B, spirocysts; E, L, basitrichs S; H, N, p-mastigophore A; M, b-mastigophore; O, p-mastigophore B1.

TABLE 3.
Size ranges and distribution of cnidae of Actinostella californica (McMurrich, 1893). Data in parenthesis of Phyllactis concinnata (Drayton) from Carlgren (1951). N, Total number of capsules measured; M, Ratio of number of specimens in which each cnidae was found to number of specimens examined; F, Frequency, +++ = very common, ++ = common, + = rather common, --- = sporadic; SD, standard deviation; ND, no data; NF, not found. Sizes in micrometers. Letters in parenthesis after categories correspond to images in figure 9. (*) Category named as basitrichs by Carlgren (1951).

FIG. 10.
External anatomy of Actinostella digitata (McMurrich, 1893). A, lateral view of live semiexpanded specimen; B, lateral view of preserved specimen; C, detail of vesicles (ve) in the marginal ruff; D, lateral view of preserved syntype (USNM 1776); E, lateral view of preserved syntype (USNM 1776) showing rows of verrucae (v) in distal column; F, oral view of preserved syntype (USNM 1776) showing the marginal ruff (f). Abbreviations: f, marginal ruff; v, verrucae; ve, vesicles. Scale bars: A, B, D, 10 mm; E, F, 5 mm; C, 0.1 mm.

FIG. 11.
Internal anatomy of Actinostella digitata (McMurrich, 1893). A, longitudinal section of the distal column showing distal vesicles (ve) in the marginal ruff, marginal sphincter muscle (s), and the fosse; B, cross section proximal to the actinopharynx level showing cycles of mesenteries, and the siphonoglyph (si); numbers between pairs of mesenteries indicate the corresponding cycle; C, detail of verrucae (v) in distal column; D, cross section of a tentacle showing ectodermal longitudinal muscles; E, detail of developing spermatic cysts (sc); F, detail of a cross section showing the retractor (r) and parietobasilar (p) muscles; G, cross section of proximal end showing weak basilar muscles (b). Abbreviations: b, basilar muscles; ep, epidermis; ga, gastrodermis; me, mesoglea; sc, spermatic cysts; p, parietobasilar muscle; r, retractor muscle; s, sphincter; si, siphonoglyph; t, tentacle; v, verrucae; ve, vesicles. Scale bars: A, F, 5mm; B–E, G, 1 mm.

FIG. 12.
Cnidae of Actinostella digitata (McMurrich, 1893). A, B, D, F, G, H, J, K, basitrichs; C, spirocysts; L, basitrichs S; E, I, N, p-mastigophore A; M, b-mastigophore; O, p-mastigophore B1. Capsules depicted in K and O were found only in type specimens.

TABLE 4.
Size ranges and distribution of cnidae of Actinostella digitata (McMurrich, 1893). Data in parenthesis from Carlgren (1934). N, Total number of capsules measured; M, Ratio of number of specimens in which each cnidae was found to number of specimens examined; F, Frequency, +++ = very common, ++ = common, + = rather common, --- = sporadic; SD, standard deviation, ND, no data; NF, not found. Sizes in micrometers. Letters in parenthesis correspond to images in figure 12.

FIG. 13.
External and internal anatomy of Actinostella flosculifera (Le Sueur, 1817). A, lateral view of living relaxed specimen in aquarium, B, lateral view of semirelaxed live specimen; notice rows of distal verrucae (v); C-E, oral view of specimens in the field, burrowed with only marginal ruff above the substratum; F, longitudinal section of the distal column showing the position of the endodermal marginal sphincter muscle (s); G, H, detail of variability of the endodermal marginal sphincter muscle in two specimens. Abbreviations: f, marginal ruff; od, oral disc; s, sphincter; v, verrucae; ve, vesicle. Image in A courtesy of V. Häussermann. Scale bars: A, B, 5 mm; C, D, E, 10 mm; F, 1 mm; G, H, 0.5 mm.

FIG. 14.
Cnidae of Actinostella flosculifera (Le Sueur, 1817). A, C, E, H, I, K, L, M, basitrichs; B, spirocysts; F, N, basitrichs S; D, G, J, P, p-mastigophore A; O, b-mastigophore; Q, p-mastigophore B1.

FIG. 15.
Phylogenetic reconstruction of rDNA dataset using RaxML-NG. Colored triangles depict collapsed suborder Anenthemonae, and superfamilies Actinostoloidea and Metridioidea; dotted line represents suborder Enthemonae. Only bootstrap support for taxa within the genus Actinostella showed.


TABLE 5.
Size ranges and distribution of cnidae of Actinostella flosculifera (Le Sueur, 1817). N, Total number of capsules measured; M, Ratio of number of specimens in which each cnidae was found to number of specimens examined; F, Frequency, +++ = very common, ++ = common, + = rather common, --- = sporadic; SD, standard deviation, ND. Sizes in micrometers. Letters in parenthesis correspond to images in figure 14.

TABLE 6.
Differential diagnostic characters of Actinostella species from American coasts.

FIG. 16.
External and internal anatomy and cnidae of Lophactis ornata Verrill, 1869 (YPM 2105) (= Telmatactis cf. panamensis). A, lateral view of preserved specimen; B, oral view of preserved specimen; notice the capitulum (c); C, proximal view of preserved specimen; D, longitudinal section of the distal column showing mesogleal marginal sphincter muscle (s); E, detail of the muscle fibers within the mesoglea; F–H, basitrichs; I, p-mastigophores B1. Scale bars: A–D, 5 mm; E, 1 mm.

TABLE 7.
Size ranges and distribution of cnidae of Lophactis ornata Verrill, 1869 [=Telmatactis panamensis]. N, Total number of capsules measured; M, Ratio of number of specimens in which each cnidae was found to number of specimens examined; F, Frequency, +++ = very common, ++ = common, + = rather common, --- = sporadic; ND, no data. Sizes in micrometers. Letters in parenthesis correspond to images in figure 16. Data sources: 1Fautin et al. (2007); 2Carlgren (1951).

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