Revision of Chaetacanthus Seidler, 1922 (Annelida, Phyllodocida, Polynoidae).

The polynoid genus Chaetacanthus Seidler, 1922 currently includes three nominal species provided with parapodial branchiae. Members of this taxon have palps with longitudinal rows of papillae, notochaetae abundant and neurochaetae spinulose. Most Chaetacanthus species were originally described as belonging to Lepidonotus Leach, 1816, and some of them were later regarded as subjective synonyms of Iphione magnifica Grube, 1876, the type species for Chaetacanthus. This species was described from the Caribbean Sea and later recorded for the tropical Eastern Pacific. After the supposed Amphi-American distribution, a revision of all available material was performed in order to clarify the generic delineation, and to improve the understanding of species systematics. Further, some non-type specimens collected in Panama allowed us to have a better understanding of the variation of elytral shape and ornamentation along the body. The type material of Polynoe brasiliensis de Quatrefages, 1866 was examined and despite its poor condition, it shows parapodial branchial filaments which were overlooked in the original description; these branchiae are also present in the holotype of I. magnifica. We identify that there are no relevant difference between both species, and they are regarded as synonyms, and Chaetacanthus brasiliensis (de Quatrefages, 1866) is newly combined and is the senior synonym. On the other hand, Chaetacanthus pilosus (Treadwell, 1937), from the Eastern Pacific, and C. pomareae (Kinberg, 1856) from the South Central Pacific are redescribed, and C. harrisae n. sp., and C. ornatus n. sp. are both newly described from the Eastern Pacific. A key to identify all species of Chaetacanthus of the World, together with an appendix for the reversal of precedence of Lepidonotus Leach, 1816 over Eumolpe Oken, 1807 are also included.

Kristianides, A New Genus of Scale Worms from the Northern Gulf of Mexico and New Records of Phyllohartmania taylori (Annelida: Polychaeta: Polynoidae).

Phyllohartmania Pettibone, 1961 is a monotypic genus in the subfamily Polynoinae Kinberg, 1856. It is characterized by having lateral antennae with ventral ceratophores, cephalic peaks and neuropodia with pre-chaetal lobes being longer than post-chaetal lobes. Phyllohartmania taylori Pettibone, 1961 was described using only one specimen collected at Bird Point, Seahorse Key, Florida. During a study of Polynoids from the Grand Caribbean to corroborate features and records, the holotype and additional material of P. taylori housed at the National Museum of Natural History, Smithsonian Institution were examined and an unknown genus of Eulagiscinae Pettibone, 1997 confused with Phyllohartmania was found; the present study erects this as a new genus. Kristianides gen. nov. is distinguished by having prostomium without cephalic peaks, lateral antennae inserted terminally on indistinct ceratophores and notopodia and neuropodia with projecting acicular lobes well developed. Kristianides cylindricum sp. nov. differs from the other species of Eulagiscinae by having ventral lamellae; 15 pairs of elytra with fringe of papillae, surface with sclerotized microtubercles and macrotubercles; being conical the microtubercles and cylindrical the macrotubercles. In addition, two records of P. taylori from the northern Gulf of Mexico are published herein, as is a taxonomic key to differentiate Kristianides gen. nov. from its congeners in Eulagiscinae. This finding also increases the number of species with ventral lamellae, a convergent feature.

Lepidasthenia loboi sp. n. from Puerto Madryn, Argentina (Polychaeta, Polynoidae).

Among polychaetes, polynoids have the highest number of symbiotic species found living with a wide variety of marine invertebrates, including other polychaetes. Lepidasthenia Malmgren, 1867 and Lepidametria Webster, 1879 were regarded as synonyms but belong to different subfamilies, although both have species associated with thelepodid or terebellid polychaetes. In this contribution Lepidasthenia loboi sp. n. is described from several specimens associated with the thelepodid Thelepus antarcticus Kinberg, 1867, collected on a rocky shore near Puerto Madryn, Argentina. Lepidasthenia loboi sp. n. can be confused with Lepidasthenia esbelta Amaral & Nonato, 1982 because both live with Thelepus, are of similar sizes with similar pigmentation patterns, and have giant neurochaetae. However, in Lepidasthenia loboi sp. n. all eyes are of the same size, cephalic and parapodial cirri are tapered and mucronate, the second pair of elytra is larger than the third, the ventral cirri arise at the base of parapodia such that they do not reach chaetal lobe tips, and neuraciculae are tapered. On the contrary, in Lepidasthenia esbelta the posterior eyes are larger than anterior ones, cephalic and parapodial appendages are swollen subdistally, the second and third pairs of elytra are of the same size, the ventral cirri arise medially such that their tips reach the neurochaetal lobe tips, and the neuraciculae have falcate tips. Some comments about other genera in the Lepidastheniinae, a simplified key to its genera, and a key to Lepidasthenia species with giant neurochaetae are also included.

Revision of Lepidonopsis humilis (Augener, 1922) and description of L. barnichae sp. nov. (Annelida: Polychaeta: Polynoidae) based upon morphological and molecular characters.

Lepidonopsis humilis (Augener, 1922) has been considered as an amphiamerican species, widely recorded in both the Grand Caribbean region and the Tropical Eastern Pacific. Based on type material and additional materials, L. humilis is redescribed herein and its distribution clarified and restricted. Furthermore, the identity of specimens from the Mexican Pacific is clarified and a new species L. barnichae sp. nov. is described. This species is characterized by conical macrotubercles with slightly curved tips; all elytra with a tuft of papillae on the surface, isolated from the marginal papillae; and the second segment dorsally projecting over the prostomium as a small lobe. Additionally, there is a 17.6% genetic divergence in the nucleotide sequence variation of COI between L. humilis and L. barnichae sp. nov., which supports the morphological differences observed. Thus, L. humilis does not have an amphiamerican distribution but is restricted to the Gran Caribbean region; whereas the specimens from the Tropical Eastern Pacific belong to the newly described species L. barnichae sp. nov. A key to the three known species of Lepidonopsis is included.