Heteranthus Klunzinger, 1877

Yap, Nicholas Wei Liang, Quek, Zheng Bin Randolph, Tan, Ria, Nugroho, Dharma Arif, Lee, Jen Nie, Lee Berumen, Michael, Tan, Koh Siang & Huang, Danwei, 2021, Carlgren’s hesitation allayed: redescription and systematics of Heteranthus verruculatus Klunzinger, 1877 (Cnidaria, Actiniaria), with a redefinition of Heteranthidae Carlgren, 1900, Contributions to Zoology 90 (2), pp. 155-182 : 162-163

Genus Heteranthus Klunzinger, 1877

Diagnosis modified after Carlgren (1949) and Fautin et al. (2008: 52). Substantial changes from our research are indicated in bold; all minor additions are in italics.

Diagnosis. Pedal disc well-developed. Column, apart from most proximal part, with verrucae, which are smaller and more numerous at the margin, and overhang the fosse, resembling papillae. Endodermal marginal sphincter muscle, restricted to circumscribed in form, may form a few folds. Tentacles as marginal and discal tentacles. Marginal tentacles conical, simple, without ramified protuberances, arranged in cycles, innermost cycle longer than outermost; discal tentacles shorter and papilliform, arranged as dense or sparse radial rows. Siphonoglyphs well-developed, when present. Number of directives pairs, and pairs of complete and incomplete mesenteries variable, gametogenic tissue may be present on both; retractor muscles diffuse to diffuse circumscript, well developed. Parietobasilar muscles weak to fairly strong. Frequently propagates by longitudinal fission. Cnidom: spirocysts, basitrichs, microbasic amastigophores, microbasic p -mastigophores

Gender. Masculine

Type species. Heteranthus verruculatus Klunzinger, 1877 , by monotypy (see Fautin, 2016)

Remarks. Carlgren (1949: 75) stated that the column is “provided with large verrucae,” but we found this character to be variable in size and visibility, among preserved specimens. We adhere to the rewording by Fautin et al. (2008) in not specifying size of verrucae to allow for this variation. On marginal tentacles, Klunzinger (1877) reported that these were of equal length, but Fautin et al. (2008) found otherwise in studying live specimens. Likewise, we observed that the innermost cycle of marginal tentacles was longer than those at the outermost in living individuals. Note that in many preserved specimens, this feature may be less-pronounced and tentacles may contract. Specification of the number of siphonoglyphs present was removed as this varied among individuals or be absent entirely. Similarly, the number of directive pairs, and pairs of complete and incomplete mesenteries also varies among individuals. Like both Carlgren (1949) and Fautin et al. (2008), we too failed to find any gametogenic tissues in all but those specimens from Western Australia. Moreover, we observed that living polyps readily undergo longitudinal fission. The diagnosis is modified to indicate the presence of gametogenic tissue in some individuals and its reproductive mode.

We confirm the presence of microbasic amastigophores in live materials examined for cnidae; this cnidae type has not been reported in Heteranthus . Because unfired capsules of microbasic amastigophores strongly resemble those of microbasic p- mastigophores in preserved specimens, they may have been mistaken for the latter and were not reported (see Östman, 2000; Yap et al., 2014).