Acromegalomma Gil & Nishi, 2017

Rebello, João Gabriel, Nogueira, João Miguel De Matos & Carrerette, Orlemir, 2025, Description of four new species of Acromegalomma (Annelida, Sabellidae) from the Coast of Brazil (SW Atlantic), with comments on the morphological characters of the genus, Zootaxa 5620 (1), pp. 72-104 : 75-77

Genus: Acromegalomma Gil & Nishi, 2017

Type species: Branchiomma köllikeri Claparède 1868 , a junior synonym of Sabella lanigera Grube, 1846 .

Diagnosis (sensu Tovar-Hernández & Carrera-Parra 2011 and Capa et al. 2021). Medium- to large-sized sabellids, with variable number of radioles, each with numerous rows of vacuolated cells as radiolar skeleton. Basal membrane and radiolar flanges both absent. Single compound, sessile eye subdistally on inner margin of one or more pairs of radioles. Dorsal lips with radiolar appendages; pinular appendages may be present. Ventral radiolar appendages absent. Ventral lips and parallel lamellae both resent, ventral sacs also usually present. Keel or caruncle present in some species. Collar chaetae elongated narrowly hooded, similar to notochaetae of upper rows of subsequent chaetigers; lower thoracic notochaetae hooded. Thoracic uncini avicular, with several rows of equal-sized teeth above main fang, developed breast, and medium-sized manubrium, companion chaetae present. Abdominal uncini similar to thoracic ones, but with shorter manubrium. Abdominal neurochaetae hooded in both groups. Pygidial ocelli sometimes present.

Remarks. The main morphological character joining members of all species within Acromegalomma is the presence of large subdistal compound eyes, on the inner edge of radioles but, the definition of the genus is primarily based on three key characters, as suggested by Knight-Jones (1997): the fusion of the dorsal collar margins to the faecal groove and the presence of both dorsolateral pockets on the collar and subdistal compound radiolar eyes on the branchial crown. Tovar-Hernández & Salazar-Vallejo (2008) expanded this diagnosis by identifying the presence of a caruncle – an elongated triangular lobe between the dorsal lips – as a significant feature. This classification was further refined by Capa & Murray (2009), who described three new species from Australia.

Currently, the genus Acromegalomma comprises 38 valid species ( Read & Fauchald 2025), of which 13 species have been described from localities on the Atlantic Ocean, mostly from the Northern Atlantic. These include A. bioculatum , A. heterops , A. lobiferum ( Ehlers, 1887) , A. perkinsi ( Tovar-Hernández & Salazar-Vallejo, 2006) , all from the coast of Florida, USA; A. georgiense (Tovar-Hernández & Carrera-Parra, 2011) , from off of Georgia, USA; A. fauchaldi ( Giangrande, Licciano & Gambi, 2007) , from Carrie Bow Cay, Belize; A. vesiculosum ( Montagu, 1813) from off the United Kingdom; A. lanigerum ( Grube, 1846) , from the coast of Italy, and A. adriaticum ( Giangrande, Caruso, Mikac & Licciano, 2015) , A. longoventrale ( Giangrande, Caruso, Mikac & Licciano, 2015) , A. messapicum ( Giangrande & Licciano, 2008) and A. pseudogesae ( Mikac, Giangrande & Licciano, 2013) , all from the Adriatic Sea.

From the Southwestern Atlantic, only A. schwindtae Tovar-Hernández, de León-González & Bybee, 2017 was described, from off Patagonian Argentina, and we describe herein four new species from southeastern Brazil.