Adeonellopsis MacGillivray, 1886

Liow, Lee Hsiang & Gordon, Dennis P., 2020, New species of Adeonellopsis (Bryozoa: Adeonidae) from southern Zealandia and the western Tasman Sea, Zootaxa 4895 (3), pp. 301-331 : 304-305

Genus Adeonellopsis MacGillivray, 1886

Type species. Adeonellopsis foliacea MacGillivray, 1886 .

Remarks. Some species of Adeonella (a genus not found in the New Zealand Exclusive Economic Zone (EEZ)) can have colonies that look very like those of Adeonellopsis ( Hayward 1988) , but the frontal shield in Adeonella forms in the same way as lepralioid-shielded cheilostomes, such that the spiramen is strictly peristomial, opening internally above the level of the primary orifice.

Adeonellopsis baccata ( Hutton, 1878) from South Australia is nominally the sole wholly encrusting species of Adeonellopsis ( Gordon & Parker 1991) , i.e. having no erect extensions from an encrusting base. It is here transferred to Reptadeonella Busk, 1884 , a genus typified, inter alia, by wholly encrusting colonies in which zooids have uniporous spiramina. The congruity of the encrusting colony form in Reptadeonella is supported by a molecular tree in which three included species form a well-supported monophyletic clade ( Orr et al. 2019). Multiporous autozooidal spiramina in Reptadeonella are rare, co-occur with uniporous spiramina in the same species, or are formed differently ( Cheetham et al. 2007; Yang et al. 2018). Although early astogeny is not yet known for Reptadeonella baccata n. comb., the uniporous autozooidal spiramina (simple or spoked) and dried colony colour (said to be ‘leaden grey’ in its junior synonym Adeonellopsis zietzii MacGillivray, 1889 ) are consistent with typical pigmented Reptadeonella .

Although introduced in 1884, Reptadeonella as a genus remained unused until adopted by Canu & Bassler (1928). Its type species, Lepralia violacea Johnston, 1847 , was included by Jelly (1889) as a junior synonym of a Microporella species in her Synonymic Catalogue, in which she did not even mention Reptadeonella . MacGillivray seems to have been either unaware of Reptadeonella or not convinced of its validity; it is not indexed in the Prodromus of the Zoology of Victoria or in MacGillivray’s (1890) postscript to the volumes and it is logical that he would therefore have included the encrusting zietzii in his genus Adeonellopsis , there being no other obvious alternative. Inasmuch as there are two undescribed species of Reptadeonella in the Great Australian Bight (P.E. Bock, pers. comm.), R. baccata is not geographically isolated. As herein defined, all Adeonellopsis species are erect, even if some, like Adeonellopsis sparassis ( Ortmann, 1890) , initially have a small encrusting base ( Hirose 2016).

Finally, the vast majority of Adeonellopsis species have multiporous autozooidal spiramina, as in the earliest named species ( Gordon & Taylor 2015). Adeona , in contrast, characteristically has a single spiraminal pore. For example, in the molecular-genetic analysis by Orr et al. (2019), all their single-pored Adeona samples (from Western Australia) formed a statistically supported clade, whereas the sister clade, Adeonellopsis (samples from Australia and New Zealand), had multiporous spiramina with marginal spikes. Adeonellopsis Japonica ( Ortmann, 1890) , a Japanese species of intermediate morphology, has 2–3 spiraminal pores in autozooids (and a multiporous spiramen in gonozooids) but radial spikes are lacking or are just short bumps. The species grouped with Adeona in Orr et al. ’s (2019) tree and was accordingly transferred to Adeona . One or a very few spiraminal pores lacking spikes is a potential key character for discriminating morphologically intermediate Adeona species from Adeonellopsis , which is proximal to Adeona in the molecular tree. The Indo-West Pacific species Adeona arculifera Canu & Bassler, 1929 has only a single, non-spicate, spiraminal pore. It was transferred to Adeonellopsis by Hirose (2016) on the basis of colony form, but the form of the spiramen indicates it should be retained in Adeona .