Treadwellphysa Molina-Acevedo and Carrera-Parra, 2017

Molina-Acevedo, Isabel C., 2019, Redescription of two species previously regarded as Marphysa de Quatrefagesı 1865 ı with the description of new species of Treadwellphysa Molina-Acevedo and Carrera-Parraı 2017, Journal of Natural History 53 (9), pp. 517-540 : 519-520

Genus Treadwellphysa Molina-Acevedo and Carrera-Parra, 2017 Type species Treadwellphysa yucatanensis Molina-Acevedo and Carrera-Parra, 2017

Diagnosis

Modified after Molina-Acevedo and Carrera-Parra 2017. Prostomium bilobed; five prostomial appendages arranged in a semicircle; eyes present; peristomial cirri absent; branchiae never starting before chaetiger 15 and continuing along the body, branchial filaments digitiform. Maxillary apparatus with four pairs of maxillae and an unpaired one on the left side; maxillae I forceps-like, without attachment lamella; with falcal arch angular shaped, well developed; base of maxilla with straight outer edge and basal inner with a curvature where the base of MII is supported, and without attachment lamella. Maxillae II without attachment lamella, inner base with a small rounded projection that fits in the curvature of the basal inner edge of maxillae I; with cavity opening of similar size in left and right MII, upper end reaching same height as basal tooth. Maxilla III curved, forming part of distal arc, with attachment lamella, sclerotised, situated at the centre of posterior edge of maxilla. Maxillae IV with wide attachment lamella, strongly sclerotised, situated on posterior edge of maxilla. Maxillae V unidentate. Parapodia with dorsal cirri without articulation, longer than or similar in size to ventral cirri, gradually decreasing in size in median-posterior parapodia; ventral cirri with swollen base as a transverse welt with short digitiform tip, in more than half of parapodia of the body; postchaetal lobe poorly developed. Supracicular chaetae include limbate chaetae and three types of pectinate chaetae: isodont narrow in anterior region; wide, isodont in median-posterior region; and anodont wide in posterior region. Subacicular chaetae include compound falcigers always present, spinigers and spinifalcigers sometimes present; subacicular hooks bidentate.

Remarks

Initially, Treadwellphysa was proposed for species having three main characters in common: the shape of the maxillary apparatus, the ventral cirri with a swollen base as a transverse welt, and the presence of the compound spinifalciger chaetae. These features are present in the four currently valid species distributed in the Grand Caribbean: T. amadae , T. languida , T. veracruzensis and T. yucatanensis . However, after a thorough examination of parapodia, the spinifalciger chaetae were not found in the species herein studied from both the Tropical Eastern Pacific and the Tropical South Atlantic.

Four more species are herein included in this genus: T. dartevellei (Monro, 1936) comb. nov., T. mixta (Fauchald, 1970) comb. nov., T. rizzoae sp. nov. and T. villalobosi sp. nov.