A revision of the New World species of Ricinus (Mallophaga) occurring on Passeriformes (Aves)

Species of Ricinus (Mallophaga:Amblycera) that are ectoparasites of passerine birds in the New World are revised. The genus occurs on members of 28 of the 70 families of Passeriformes. A relict distribution is indicated. Little biological information is available for species of Ricinus. Rates of incidence and infestation usually are low, at least in California. Observations that are available indicate an apparent concordance in the reproductive seasons of the lice and their hosts. "Preferred" ovipositional sites are demonstrated. Hematophagia as an exclusive method of feeding is strongly suggested by piercing- sucking mouthparts and the presence of blood in the gut. An investigation of the zoonotic role of species of Ricinus is needed. A historical review of the extreme confusion that has surrounded the status of the name Ricinus and that of its type species R. fringillae is presented. Their status is now fixed and accepted through the declaration of Opinion 627 by the International Commission of Zoological Nomenclature. The external morphology of the species of Ricinus is described, with emphasis on the salient features used in defining and recognizing species. A system of chaetotaxy is erected. Measurements of various structures are of little use in defining species because of presence of much intraspecific variation and apparent host-induced variation. Characters found to have diagnostic value and the shape of structures, the pigmentation pattern, and the chaetotaxy. A species is defined on the basis of multiple characters. A hypothetical phylogeny is proposed for the genus Ricinus and its species, based upon modifications of several structures found on extant forms. Changes in the structure of the labium, labrum, mandibles, tentorium, and thorax among others demonstrate the Ricinus is a specialized genus in the suborder Amblycera. Specializations exhibited within the genus indicate that Ricinus had undergone two separate radiations, interspersed by a period of decline. The genus is redescribed and divided into eight species groups. Thirty-eight species are considered valid. Twenty-five specific and subspecific names are judged Synonyms. Five names are designated species inguirendae. Ricinus nigrolimbetus (Mjoberg, 1910) is designated nomen dubium. Twenty-four species are redescribed, of which four, R. arcuetus, R. fringillae, R. marginatus, and R. sucinaceus, are given sensu lato status. Fourteen new species are described: R. celcarii, R. carolynae, B. dalgleishi, R. dendroicae, B. emersoni, R. mandibulatus, R. myiarchi, R seiuri, R sittae, R. subdiffusus, R. vireoensis, R. volatiniae, and R. wolfi. Certain species of Ricinus show host specificity at the specific, generic, and family level, Certain species groups show host specificity at the family, super- family, or subordinal level. These forms are found useful in deducing probable host, phylogeny. Other species and. species groups are distributed so anomalously that no correlation is apparent between the evolution of the lice and their hosts. It is proposed. that secondary transfers have occurred, obscuring any phylogenetic relationship. The potential for and. occurrence of secondary transfer are discussed and shown to be more common than previously realized. A seemingly anomalous distribution of a louse on two or more species of host probably indicates an ecological relationship for the hosts involved. Several cases are resolved in which two and, rarely, three species of Ricinus regularly occur on the same host species. This synoxenic distribution follows no geographical or taxonomic pattern.