Actinostella bradleyi ( Verrill, 1869 )

Barragán, Yamaly, Rodríguez, Estefanía, Chiodo, Tommaso, Gusmão, Luciana C., Sánchez, Carlos & Lauretta, Daniel, 2024, Revision of the genus Actinostella (Cnidaria: Actiniaria: Actinioidea) from tropical and subtropical western Atlantic and eastern Pacific: redescriptions and synonymies, American Museum Novitates 2024 (4014), pp. 1-48 : 11-19

Actinostella bradleyi ( Verrill, 1869)

Figures 2–6, tables 1, 2

Asteractis bradleyi Verrill, 1869 .

Phyllactis bradleyi ( Verrill, 1869) : Stephenson, 1922.

Non Phyllactis bradleyi ( Verrill, 1869) : Carlgren, 1951.

Actinostella bradleyi ( Verrill, 1869) : Häussermann, 2003.

Actinostella californica ( McMurrich, 1893) : Barragán et al., 2019 pro parte.

DIFFERENTIAL DIAGNOSIS: Actinostella with up to four cycles of mesenteries and 96 tentacles, all mesenteries, including directives, perfect and fertile. Marginal ruff and column with p -mastigophores A and basitrichs.

EXAMINED MATERIAL: Actinostella bradleyi : AMNH_IZC 00361355, AMNH_IZC 00361356, AMNH_IZC 00361357, AMNH_IZC 00361358, USNM 1606849, USNM 1606850; Asteractis bradleyi Verrill, 1869 [= A. bradleyi ]: YPM 1009 (holotype). Lophactis ornata Verrill, 1869 [= Telmatactis cf. panamensis ( Verrill, 1869) ]: YPM–2015 (holotype). YPM repository IZAR.001433: Frank Howe Bradley Correspondence; 1866–1867; Correspondence from F.H. Bradley to A.E. Verrill; all sent from his expedition to America Central (letters transcribed by E. Lazo-Wasem).

DESCRIPTION: External anatomy (figs. 2, 5): Well-developed pedal disc, to 23 mm diameter. Column elongate, to 55 mm height and 42 mm diameter, with 96 longitudinal rows of verrucae distally in each endo- and exocoel. Marginal ruff with rows of vesicles. Oral disc to 34 mm diameter. Fosse deep. Tentacles, to 96 in five cycles; simple, smooth, all similar length, to 18 mm. Mesenterial insertions visible in pedal disc.

Internal anatomy (figs. 3, 5): Same number of mesenteries distally and proximally. Fortyeight pairs of mesenteries hexamerously arranged in four cycles (6 + 6 + 12 + 24 = 48). All cycles perfect and fertile, including directives (fig. 3B). Two pairs of directives attached to two clearly distinct siphonoglyphs. Gonochoric, developed oocysts 0.06–0.15 mm in diameter (fig. 3F) in specimen collected in May 2013, developed spermatic cysts 0.09–0.23 mm in diameter (fig. 3E) in specimens collected in August, October, and November 2013. Retractor muscles strong, bandlike, and restricted. Parietobasilar muscles well developed (fig. 3G), with long free mesogleal lamella. Basilar muscles well developed, processes short and thin (fig. 3H). Endodermal marginal sphincter muscle circumscribed (fig. 3A, C). Longitudinal muscles of tentacles ectodermal (fig. 3D). Zooxanthellae present in tentacles and marginal ruff.

Color (fig. 2): Variable in live specimens. In specimens from Mexico, pedal disc and column pinkish or opaque orange; verrucae darker than column. Oral disc olive green with beige radial lines. Marginal ruff olive green with radial brown and beige stripes. Tentacles brownish or reddish with brown base and spots with a brown dot along the entire tentacle. Specimens from Panama, same pedal disc, column, and oral disc, but with brownish marginal ruff. Preserved material beige and marginal ruff lighter.

Cnidom (figs. 4, 6): Basitrichs, basitrichs S, b -mastigophores, p -mastigophores A, p -mastigophores B1, and spirocysts. Sizes and distribution in table 2.

GEOGRAPHIC AND BATHYMETRIC DISTRIBUTION AND NATURAL HISTORY: Actinostella bradleyi can be found in the Pacific Ocean in Mexico and Panama. Although Verrill (1869) did not specify the location of the type locality (i.e., Panama Reef) in the Pacific, we confirm the type locality of A. bradleyi in the Pacific side of Panama, off the coast of Panama City based on transcriptions of the original correspondence (archived record IZAR.001433) between Verrill and F.H. Bradley (collector). In Mexico, A. bradleyi can be found on the intertidal shore in Pichilingue Bay in the Gulf of California and in Conquista Agraria and Magdalena Bay on the Pacific side. In Panama, this species was collected in the Azuero Peninsula (Los Santos Province) and the Pearl Islands (Gulf of Panama Province) between 3– 10 m. The specimens were found burrowed in sand attached to a buried rock or shell, or hidden in rock crevices, with the marginal ruff above the substratum. Actinostella bradleyi and A. californica live in sympatry, although in Mexico, A. californica is more common (and found at shallower depths) than its Pacific congener.

REMARKS: Actinostella bradleyi differs from the five other species of the genus by the combination of the number of tentacles (up to 96), perfect mesenteries and distribution of fertile cycles of mesenteries (all four cycles), and the presence of p -mastigophores A in the marginal ruff and column (figs. 4, 6). Until the specimens analyzed by Ocaña (1994) from the Canary Islands are examined, A. bradleyi is the only species within the genus with up to five cycles of tentacles and four cycles of mesenteries. Although externally A. bradleyi closely resembles the only other species of the genus recorded from the eastern Pacific, A. californica , they can be easily distinguished in the field by the number of tentacles (to 96 in A. bradleyi and up to 48 in A. californica ). However, both species live in sympatry and when specimens of A. bradleyi are not completely mature, as it is the case of the holotype of the species (YPM 1009), they can be confused with A. californica . Attributes of the cnidom can differentiate them. Barragán (2015) redescribed one sterile specimen with three cycles of mesenteries collected in Pichilingue Bay in the Gulf of California ( Mexico) and considered it as A. californica based mainly on its distribution. Our detailed revision of this material here shows that this specimen is an immature specimen of A. bradleyi in which the fourth cycle of mesenteries is not yet developed.

Fautin (2016: 177) cited under the list of synonymies of Actinostella bradleyi the following: “ Oulactis californica McMurrich, 1893 [Ref. 386], p. 196–197, 198, 206 (original description).” This synonymy is incorrect because those specimens correspond to the type material of the species A. californica . In addition, Fautin (2016) mentioned as valid names used for Oulactis californica McMurrich, 1893 , both A. bradleyi and A. californica . In this study, we show that O. californica is a synonym of A. californica ( McMurrich, 1893) and different from A. bradleyi (see remarks under A. californica ).