Jessethoa, Gordon, 2020

Gordon, Dennis P., 2020, New Hippothoidae (Bryozoa) from Australasia, Zootaxa 4750 (4), pp. 451-476 : 460-461

Jessethoa n. gen.

Type species. Jessethoa ausubeli n. sp.

Etymology. Honorific for Jesse H. Ausubel, science advisor and former Vice President of Programs at the Alfred P. Sloan Foundation, New York, in recognition of his critical role in the decade-long Census of Marine Life; - thoa is a common suffix for hippothoid genera.

Diagnosis. Colony encrusting, uniserial, zooidal branches ramifying, becoming densely crowded and contigu- ous. Autozooids claviform with non-filiform cauda, with few to many frontolateral gymnocystal pores (pseudopores and pore-chamber openings), some quite large; lateral-most pore-chambers may bud or connect with adjacent zooids autozooids or polymorphs. Orifice with deep round sinus. Female cystid same size as autozooid but with larger (dimorphic) orifice, bearing relatively large terminal cleithral ovicell; ooecium with numerous pseudopores and larger peripheral pore-chamber openings that are budding loci. Zooeciules abundant, budded from autozooids, female zooids, ooecial kenozooids and other zooeciules; a frontal zooeciule also budded on middle of autozooidal shield in mature parts of colony. Ancestrula resembling autozooid but tending to be oval in outline; able to bud proximally as well as distally.

Remarks. Jessethoa ausubeli n. gen., n. sp. is highly distinctive among hippothoid genera, for a number of reasons:

1) The unique occurrence of frontally budded zooeciules on many autozooids, other zooeciules, female cystids and even ooecia.

2) The presence of frontolateral gymnocystal pores, some quite large. Pores along zooidal margins are frontal expressions of basolateral pore-chambers; smaller pores in the frontal shield are genuine pseudopores, which are otherwise unknown in Hippothoidae sensu stricto but are typical of Trypostegidae . Frontal-shield pseudopores are not found in axial runner zooids but can be abundant in all zooids in crowded parts of colonies.

3) The form of the dimorphic orifices. Such are found in other genera of Hippothoidae , but none has autozooids with such cleithridiate orifices or the broad wedge-shaped female sinus resembling a rounded mincing knife (mezzaluna).

4) Interzooidal zooeciules that range from small and squat to elongate and narrow with the same length as an autozooid.

5) An autozooid-like ancestrula that is able to bud proximally as well as distally.