title: New species of Pisionidens (Sigalionidae, Annelida) from Akumal, México.
abstract: Pisionidens Aiyar & Alikuhni, 1943 is a genus of small scale-less annelids formerly belonging to the family 'Pisionidae', now synonymized with the scale worm family Sigalionidae. A new species from Akumal, México, Pisionidens ixazaluohae n. sp., is herein described, including a genetic barcode, and diagnosed by parapodia from segment 8, males having a continuous line of midventral pores, and the presence of a single copulatory segment without parapodia. The new species differs in morphology from the three previously described species, including P. indica (Aiyar & Alikuhni, 1940), representing the only other species previously reported from the Caribbean Sea and Gulf of Mexico. A comparative table with a summary of the main taxonomic characters of all described species of the genus, including information on distribution, is provided.
authors.affiliation: Marine Biological Section, University of Copenhagen, Universitetsparken 4, 1st floor, 2100 Copenhagen Ø, Denmark; Email: kworsaae@bio.ku.dk.
authors.forename: H Cecilie B
authors.initials: HC
authors.lastname: Petersen
authors.affiliation: Marine Biological Section, University of Copenhagen, Universitetsparken 4, 1st floor, 2100 Copenhagen Ø, Denmark; Email: unknown.
authors.forename: Brett C
authors.initials: BC
authors.lastname: Gonzalez
authors.affiliation: Marine Biological Section, University of Copenhagen, Universitetsparken 4, 1st floor, 2100 Copenhagen Ø, Denmark Consiglio Nazionale delle Ricerche, Istituto per lo Studio degli Ecosistemi CNR-ISE, Largo Tonolli 50, 28922 Verbania Pallanza, Italy.; Email: unknown.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Martínez
authors.affiliation: Marine Biological Section, University of Copenhagen, Universitetsparken 4, 1st floor, 2100 Copenhagen Ø, Denmark.; Email: unknown.
authors.forename: Katrine
authors.initials: K
authors.lastname: Worsaae
mesh_terms: D063147:Animal Distribution; D000825:Animal Structures / Q000033:anatomy & histology / Q000254:growth & development; D000818:Animals; D049628:Body Size; D017753:Ecosystem; D005260:Female; D008297:Male; D008800:Mexico; D009929:Organ Size; D011077:Polychaeta / Q000033:anatomy & histology / Q000145:classification* / Q000254:growth & development