Harenactis argentina, Lauretta, Daniel, Rodríguez, Estefanía & Penchaszadeh, Pablo E., 2011

Lauretta, Daniel, Rodríguez, Estefanía & Penchaszadeh, Pablo E., 2011, A new vermiform sea anemone (Anthozoa: Actiniaria) from Argentina: Harenactis argentina sp. nov., Zootaxa 3027, pp. 9-18 : 11-14

publication ID	https://doi.org/ 10.5281/zenodo.204615
DOI	https://doi.org/10.5281/zenodo.5675631
persistent identifier	https://treatment.plazi.org/id/0C47375A-FFE5-FFCF-FF2E-FCAE7EDDF323
treatment provided by	Plazi
scientific name	Harenactis argentina
status	sp. nov.

Treatment

Harenactis argentina View in CoL sp. nov.

Type material. Holotype: MACN - IN 39376; Punta Pardelas, Chubut, Argentina (42º 37'S, 64º 15'W), April 2008, 5– 10 m depth. Paratype: Invertebrate Collection of MLP 8791, one specimen. Collecting data same as those of holotype.

Additional material. AMNH, one specimen. Punta Pardelas, Chubut, Argentina (42º 37'S, 64º 15'W), 5–10 m depth.

Description. External anatomy: Base not adherent, physa-like, variable in shape, round or flat depending on the specimen ( Fig. 2 View FIGURE 2 a). Diameter to 21 mm (holotype 11 mm). Some specimens with abundant sand and debris attached to aboral end. Mesenterial insertions visible.

Column vermiform ( Fig. 2 View FIGURE 2 b), to 121 mm in length and 25 mm in diameter in preserved specimens (holotype 121 mm in length and 7–20 mm in diameter), smooth. In preserved specimens, column usually narrows proximally. Inconspicuous cinclides present at least distally ( Fig. 2 View FIGURE 2 c), forming 24 longitudinal rows (reaching proximal end at least in one specimen). Cinclides not perforated ( Fig. 3 View FIGURE 3 b), one row in each endo- and exo-coel. Column color whitish in vivo and in preserved specimens.

Tentacles 24 in number, arranged in three cycles; about 50% longer than oral disc diameter in live specimens; inner tentacles more or less equal in length to outer ones ( Fig. 2 View FIGURE 2 d). No apical pore. In vivo, 12 tentacles of inner cycles typically held erect, 12 of outermost cycle held parallel to substratum; tentacles completely covered in contracted specimens. Tentacles of preserved and living specimens brown. In specimens from Punta Pardelas (larger than those from Fracaso beach), 12 erected, inner tentacles brownish, with two small, whitish, V-shaped marks at adoral side of base; those 12 of outermost cycle white, with V-shaped mark at basal adoral part (to a third of tentacle length) ( Fig. 2 View FIGURE 2 d).

Oral disc round, same diameter as column. Mouth central, elevated on a cone; lips bright red in live specimens from Punta Pardelas.

Internal anatomy: Twelve pairs of mesenteries hexamerously arranged in two cycles (6 + 6), both perfect and fertile ( Fig. 3 View FIGURE 3 a). Equal number of mesenteries proximally and distally; mesenteries more developed distally, so second cycle of mesenteries poorly developed and without retractor muscles proximally. Two pairs of directives, one attached to differentiated and well-developed siphonoglyph; second pair of directives attached to more or less distinct fold of actinopharynx that is not histologically differentiated from the rest of actinopharynx ( Fig. 3 View FIGURE 3 a). Gonochoric, developing oocytes and spermatic cysts (oocytes to 0.39 mm and spermatic cysts to 0.027 mm in diameter) in specimens collected in April. Retractor muscles strongly restricted, reniform ( Fig. 3 View FIGURE 3 a). Pairs of mesenteries differentially developed: most pairs with one mesentery more developed than its partner, with larger retractor muscles (condition more evident proximally). Parietobasilar muscles strong, differentiated on all mesenteries, with short broad processes and short free mesogloeal pennon ( Fig. 3 View FIGURE 3 a).

Longitudinal muscles of tentacles and oral disc ectodermal ( Figs. 3 View FIGURE 3 c, d). Marginal sphincter muscle absent ( Fig. 3 View FIGURE 3 e). Mesogloea thick, to 0.78 mm; epidermis and gastrodermis 0.15–0.06 mm and 0.13–0.06 mm respectively at actinopharynx level. No basilar muscles ( Fig. 3 View FIGURE 3 f).

Cnidom and distribution of cnidae: Spirocysts (in tentacles, column, actinopharynx and base), basitrichs (in all tissues), microbasic p -mastigophores (in actinopharynx and mesenterial filaments) and microbasic b -mastigophores (in mesenterial filaments) ( Fig. 4 View FIGURE 4 ). See table 1 for size and distribution.

Distribution and natural history. Harenactis argentina sp. nov. inhabits soft bottoms of the Argentinean coast of Patagonia, on both sides of Península Valdés (Villarino beach, Fracaso beach and Punta Pardelas). On Fracaso beach, H. argentina sp. nov. was found on the intertidal zone, to seven specimens per square meter (the subtidal zone was not explored); it was the only sea anemone present at the beach. During low tide it is possible to see the holes this sea anemone leaves in the substratum after it contracts. On Villarino beach, H. argentina sp. nov. was found in the intertidal zone but not in the subtidal zone. On Punta Pardelas, it was only found in the subtidal zone, starting at 5 m depth; the specimens were at least 1 m apart, co-existing with Parabunodactis imperfecta Zamponi & Acuña, 1992 (see Lauretta et al. 2009), Metridium senile lobatum ( Carlgren, 1899) and Antholoba achates (Drayton in Dana, 1846); this record of the two latter species extends their known distribution to the Santa Cruz province (DL pers. obs.).

Etymology. The specific epithet ( argentina ) refers to the country where the species has been found. The specific name argentina is used as a noun in opposition.