ABSTRACT
BACKGROUND: The sabellid genera Anamobaea Krøyer, 1856 and Notaulax Tauber, 1879 are two of the most attractive polychaete worms in coral reefs. Anamobaea is represented by two Caribbean species and Notaulax with 24 species from around the world, six of them previously known to tropical America. During examination of fouling biota and sclerozoans from Mexico, Anamobaea orstedii Krøyer, 1856 was found in coral reefs from the southern Gulf of Mexico and three species of Notaulax were identified to the Mexican Pacific, two of them being new species to science. NEW INFORMATION: Anamobaea orstedii Krøyer, 1856 is first reported as sclerozoan of dead coral from the southern Gulf of Mexico. An amendment to the generic diagnosis of Anamobaea is provided, based on the presence of a higher number of skeletal cells than previously recorded; height, shape and exposition of the anterior peristomial ring; the non-fusion of dorsal collar margins to faecal groove; shape of collar chaetiger and abdominal chaetae and distribution and shape of radiolar ocelli. Notaulax californica (Treadwell, 1906) is reported as fouling in buoys and docks from the Gulf of California. Two new species of Notaulax are described: the former was found in hull and dock fouling from La Paz (Gulf of California) and the second one as sclerozoan of oysters from a dock fouling in Acapulco (south Mexican Pacific). In addition, reproductive features are described for the first time for A. orstedii which is a simultaneous hermaphrodite with female and males gametes found within the same segments of abdominal region. Oocytes develop synchronously and sperm morphology (spherical nucleus and rounded acrosome, four spherical mitochondria and a long free flagellum) suggest an adaptation to broadcast spawning and external fertilisation. Species of Notaulax here examined were gonochoric, with gametes distributed in abdominal segments.