Pacific Science (1979), vol. 33, no. I © 1980 by The University Press of Hawaii. All rights reserved The Systematics of the Aeolidacea (Nudibranchia: Mollusca) of the Hawaiian Islands, with Descriptions of Two New Species! TERRENCE M. GOSLINER 2 ABSTRACT: Nineteen species of aeolid nudibranchs are here recorded from the Hawaiian Islands. The natural history and distribution of each species is described. Morphological accounts of these taxa are provided and their sys­ tematic status is discussed. The status of an additional three species, previously recorded from the Hawaiian Islands but not encountered in this study, is reviewed. Based on the study of the Hawaiian aeolidacean nudibranch fauna, the systematics of the Facelinidae are reviewed. An examination of the zoo­ geographical affinities of the Hawaiian aeolid fauna suggests that many taxa have a typical Indo-West Pacific distribution. However, a significant portion of the fauna is substantially more widely distributed and appears to be circum­ tropical. THE FIRST SERIOUS ATTEMPTS to characterize the islands of Oahu and Kauai and span a the Hawaiian opisthobranch fauna are those period ofover 10 years. My own 0 bservations of Kay (1961, 1962a, 1962b, 1964a, 1964b) were made from September 1972 to October and Kay and Young (1969). Kay described 1973. During this period, monthly collections most of the anaspideans and several saco­ were made at four principal sites on Oahu: glossans, and Kay and Young dealt with the Kaneohe Bay, Ala Moana Beach Park, dorid nudibranchs. Aeolid nudibranchs have Diamond Head Beach Park, and Kewalo only sporadically been described or recorded Basin. Collections were also made at other from Hawaii. Pease (1860) described two localities in the islands, including Fleming's species, Aeolis semidecora and A. parvula. Beach, Maui, and on the Kona coast, Bergh (1900) described Samla annuligera Hawaii. from Laysan Island. Edmondson (1946) At least 22 species of aeolid nudibranchs recorded five species of aeolids, but identified can be attributed to the Hawaiian Islands. only Glaucus by name. Zahl (1959) figured Three species have been recorded that were Pteraeolidia semperi and Aeolidiella sp. from not encountered in this study: Samla annu­ Kaneohe Bay, Oahu. Harris (1968, 1970) ligera Bergh (known only from the holotype recorded Phestilla melanobrachia and P. collected at Laysan); Embletonia gracile sibogae from the Hawaiian Islands. Rosin Risbec 1928 [here tentatively identified from (1969) recorded Herviella sp., and Baba a figure by Edmondson (1946)]; and Aeolis (1969) recorded Learchis indica. parvula Pease 1860 (which is not identifiable The purpose of this study is to revise the from Pease's brief description). At least five earlier work on the Hawaiian aeolids and to additional species of aeolids have been col­ report on previously unrecorded species. In lected by Kay but are not included in this this synthesis I include the collection records study because few specimens are available. of E. Alison Kay which are primarily from I Manuscript accepted 15 May 1977. 2 University of Hawaii, Department of Zoology, Honolulu, Hawaii 96822. Present address: University of New Hampshire, Department of Zoology, Durham, New Hampshire 03824. 38 PACIFIC SCIENCE, Volume 33, January 1979 Ghiselin (1965) have suggested that the gical variation and number of species. Two Aeolidacea are polyphyletic, but the evidence major groups exist, the facelinids with cuspi­ is not conclusive as the more primitive mem­ date radular teeth and the aeolidids with bers of the suborder, Notaeloidia and the pectinate radular teeth. The Aeolidiidae Coryphellidae, have been poorly studied. appear to be monophyletic, since members Odhner (1939) proposed the system of are similar in morphology and habits. Most classification whereby the aeolids are divided species are known to feed on sea anemones. into three tribes, the Pleuroprocta, Acleio­ The facelinids include a wide range of procta, and Cleioprocta, on the basis of anal morphological forms. They are the subject of position. This system is not entirely satisfac­ a great deal of taxonomic confusion and are tory, because there are numerous examples in need of revision. The controversy falls of genera that differ in anal position from into two schools of thought. One (Ernst other members of the family. Flabellina has Marcus 1958, Miller 1974) contends that the the anus intermediate to the pleuroproct and major distinction is between the favorinids, acleioproct position, whereas the remainder with the cerata grouped in arches, and the of the Coryphellidae are typically pleuro­ facelinids, with the cerata arranged in rows. proctic. Selva, a cuthonid, has the anus in the The other point of view is that of Edmunds cleioproct position, but others of the Cu­ (1970), who states that reproductive charac­ thonidae are acleioproctic (Edmunds 1964). ters, particularly the development of the One specimen of Cuthona perea (Ernst receptaculum seminis and bursa copulatrix, Marcus, 1958) in this study was cleioproctic, should take taxonomic precedence over cera­ while seven other specimens were acleio­ tal arrangement, and that ceratal arrange­ proctic. Basing aeolid classification solely on ment should be considered polyphyletic.! anal position produces a polyphyletic, and agree with Edmund's contention that a serial hence artificial, classification system. receptaculum seminis is more primitive than The pleuroprocts are considered primitive, a semiserial receptaculum. and most members (except Babakina Roller, Miller (1974) contends that Babakina Rol­ 1973) have a triseriate radula. The families ler, 1973 is not closely allied to the Cory­ within the tribe are not easily distinguished, phellidae but with the glaucids and represents and various workers subdivide the tribe into a subfamily in the Glaucidae. His argument one to five families. is primarily based on the similarity of the Like the pleuroprocts, the more primitive uniseriate radula and oral glands. Miller acleioprocts, the Eubranchidae, and possibly suggests that the two bursae in Babakina are Cuthona (Ernst Marcus 1961), are distin­ not significant in their taxonomic placement guished by a triseriate radula. The more since some coryphellids and glaucids share advanced aeolids have a uniseriate radula, as this characteristic. do most cuthonids, Fiona, and the Piseino­ I contend that it is not so much the fact that tecidae. Most acleioprocts have a simply two bursae are present that is significant, but rounded head and anterior margin of the that their structure and form are distinctive. foot. The reproductive system is distinctive The fact that Antionetta and Dietata both within the Cuthonidae, where there is a distal have two bursae and are unquestionably receptaculum seminis near the gonopore and glaucids, is not supportive of Babakina's frequently a penial gland. The acleioprocts placement in the Glaucidae as stated by seemingly have polyphyletic origins within Miller (1974). While they have advanced the Aeolidacea (Edmunds 1970). This is glaucid characteristics of cleioproctic anus, particularly evident in the cuthonids and well-developed liver system, and general body Piseinotecidae, which are similar in external form of a glaucid, they also have a serial form but have markedly different radulae and receptaculum. It is unlikely that Babakina reproductive systems. would maintain its primitive coryphellid The cleioprocts represent the most diverse characters of pleuroproctic anus, primitive tribe of aeolids in both degree of morpholo- digestive system, prominent notal brim, Aeolidacea of the Hawaiian Islands-GosLINER 39 and club-shaped rhinophores, and be more genus of his Facelininae in Phidiana-but advanced reproductively, with a semiserial recognizing several genera within his Favor­ receptaculum, when Antionetta and Dictata ininae-is inconsistent, because characteris­ retain a serial receptaculum. It seems much tics of the penis are different in both groups. more reasonable that Babakina is allied to While the distinctions of genera are not the Coryphellidae. The animals are identical precise, the maintenance of genera seems to members of the Coryphellidae except for appropriate because it stresses differences their lack of lateral rows of teeth. Miller among the groups rather than combining maintains that the oral glands of Babakina them because the differences are difficult to are glaucid. Oral glands have not been studied discern. to any degree in aeolids and cannot be deemed Miller also stated that differences in what systematically significant at present. he considers Phidiana are based entirely on Miller (1974) did not make clear whether the structure of the penis. The statement is the rhinophores in Babakina caprinsulensis erroneous. Facelinella does not have an are joined in a common insertion. Roller ejaculatory vas deferens, while Facelina does. (1972) questioned the taxonomic level at Palisa differs in having papillate rhinophores which joined rhinophores can be considered and a serial receptaculum, and its significance significant, and this question remains largely in discerning the Facelinidae is well known unsettled. (Edmunds 1970). Other genera (i.e., Hermis­ Miller suggested that the genera Glaucus senda, Emarcusia, etc.) differ significantly in and Pteraeolidia are closely allied to the radular and external form. Phidiana is unique facelinids. I feel that, while they are obviously in that members of the genus lack tentacular allied on the basis ofreproductive