I began this page re: Palythoa mammilosa cited by Lewis, may be syn. with P. caribaeorum

Intertidal Distribution of Zoanthids on the Caribbean Coast of Panama: Effects of Predation and Desiccation
KP Sebens 1982 Bulletin of Marine Science, Volume 32, Number 1, January 1982, pp. 316-335(20) “The three most common zoanthid species (Coelenterata:Zoantharia) on the intertidal reef flat at Galeta, Panama, show distinct zonation. Zoanthus sociatus occurs on the highest part of the intertidal platform while the two other species, Zoanthus solanderi and Palythoa caribaeorum have upper limits in the lower surf zone. Of the three, only P. caribaeorum continues to the subtidal fore-reef…”

Palythoa mammillosa (Ellis & Solander, 1786) Knobby zoanthidean
Distribution: Western Atlantic: St Vincent and Grenadines, USA and Canada

Palythoa (Palythoa mammillosa) Photo
Specimen from Trinidad and Tobago

The Colonial Zoanthid Palythoa caribaeorum:Population Dynamics on Southeast Florida Reefs JC Walczak – 2008 , thesis
“Current taxonomic descriptions of the genus Palythoa are outdated, and most
zoanthid researchers agree that Palythoa caribaeorum and Palythoa mammillosa are
probably the same species (Sebens 1982; Gleibs et al. 1995; Haywick and Mueller
1997). For this study, I consider them to be synonymous (possibly morphotypes) and
will therefore refer to them as the more common Palythoa caribaeorum

© CSIRO 2003 10.1071/IS02008 1445-5226/03/030407
www.publish.csiro.au/journals/is Invertebrate Systematics, 2003, 17, 407–428
Revision of methods for separating species of Protopalythoa(Hexacorallia:Zoanthidea) in the tropical West Pacific
John S. RylandA,B and John E. LancasterA “The genus Protopalythoa Verrill, 1900 (family Sphenopidae) is defined and its status discussed. As with
other zoanthid genera, species are difficult to separate by traditional methods.” discussion of P. caribaeorum

Phylogenomics of Palythoa (Hexacorallia: Zoantharia): probing species boundaries in a globally distributed genus
‘Ale‘alani Dudoit et al., Coral Reefs 41, 655–672 (2022)
Shallow Atlantic and Indian/Pacific coral reef species are generally thought to have been isolated from each other for at least 3MY, since the closing of the Isthmus of Panama (IP; O’Dea et al. 2016)…Nevertheless, some marine species may have been able to maintain limited genetic flow between these regions during interglacial periods with the
cessation of the cold-water upwelling, or through leakage of gyres of the Agulhas Current from the Indian to the Atlantic Ocean (Peeters et al. 2004; Bowen et al. 2006