Opisthobranch Mollusks from the Southern Tropical Pacific' ERNST MARCUS and EVELINE MARCUS2
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Opisthobranch Mollusks from the Southern Tropical Pacific' ERNST MARCUS and EVELINE MARCUS2 ABSTRACT : Twenty-four species of opisthobranchs are listed from the southern tropical Pacific Ocean, from Fiji and the Ellice Islands eastward to the Tuamotus. Two new genera are described: Pleurebdera (Pleurobranchidae; type species: P. haraldi n. sp., Tuamotus) and Pllpsiklls (Dorididae; type species: P. pingllis n. sp., Tahiti). Th e following five other new species and subspecies are described and figured : N oumea norba (Dorididae: Chromodoridinae, Viti Levu, Fiji) ; Perono doris rebderi (Dorididae: Archidoridinae, Tahiti); Tayuo« ketos jllva (Dorididae: Discodoridinae, Rurutu , Tubuai Islands) ; Phyllidia tula (Phyllidiidae, Nukulaelae, Ellice Islands) ; Phyllidia soria (Tahiti) . The internal anatomy of these species, as well as of many of the previously known species, is described. Many species are recorded from Polynesia for the first time. THE OPISTHOBRANCH MOLLUSKS discussed in and return of this collection through the kind this paper were sent to us for classification by offices of the U. S. General Consulate in Sao Dr. Harald A. Rehder, Smithsonian Institution, Paulo. W ashington, D. C. They were gathered by Dr. Rehder and his collectors in the tropical southern Pacific in an area centering in the LIST OF OPISTHOBRAN CHS DISCUSSED Society Islands and the neighboring Tubu ai Order Anaspid ea Islands. Some species are from the Tuamotus to the east and others from Tonga, Fiji, and the Family Aplysiidae (subfamily Dolabel Ellice Islands to the west. The collection com linae) prised 24 species, of which 7 are new and 2 1. D olabella aariculari« (Lightfoot) represent new genera. Subfamily Dolabriferinae Certainly a collection made by a resident like 2. Dolabrifera dolabrifera (Rang) Risbec in N ew Caledonia, with drawings of the Subfamily Notarchinae living animals and observations of their spawn 3. Stylocbeilus longicauda (Quoy and and mode of life, is of greater value than Gaimard) morphological studies on preserved specimens Order Notaspidea collected without drawings and accompanied by inadequate descriptions of their habitat. How Superfamily Pleurobranchacea ever, the small number of specialized workers Family Pleurobranchidae (subfamily Pleu results in the accumulation of discolored ma robranchinae) terial in the museums that would remain useless 4. Oscanius grandis (Pease) , figs. for science if they were not studied the hard 1- 7 way. 5. Plenrebdera haraldi, new genus, We are grateful to Dr. Rehder for allowing new species, figs. 8-12 us to examine this collection, and to him and Dr. Joseph Rosewater, also of the Division of Order Dorioidea Mollusks, Museum of Natural History, Smith Suborder Eudoridacea sonian Institution, for arranging the sending Tribe Hexabranchia (family Hexabran chidae) 1 Manuscript received June 2, 1969. 6. Hexabrancbus marginatus (Quoy 2 P. O. Box 6994, Sao Paulo, Brazil. D r. Ernst Marcus died on Ju ne 30, 1968. and Gaimard) 155 156 PACIFIC SCIENCE, Vol. 24, April 1970 Tribe Cryptobranchia (family Dorididae) Ecuador, the west coast of Mexico, and the Gulf Subfamily Chromodoridinae of California. 7. Cbromodoris qnadricolor (Riip COLLECTINGSTATION S : Society Islands : Pa pell and F. S. Leuckart) para, 40 km south of Papeete, Tahiti, in black 8.H ypselodoris d. godeff1'Oya na sand and under coral, depth 1-2 m, 1963, R. L. (Bergh), figs. 13-18 Sixberry, 3 specimens (USNM 576013, 576014, 9. N oumea norba, new species, figs. 576015); Arue, Tahiti, under dead coral rubble, 19-22 Subfamily Miamirinae depth 1.2 m, 1963, R. L. Sixberry, 1 specimen (USNM 575999 ). 10. Casella atromarginat« (Cuvier) 11. Orodoris miamirana Bergh, figs. DESCRIPTIVE NOTES: The shell and the male 23-26 copulatory organ characterize the species. The Subfamily Archidoridinae largest specimen ( 576014) is 140 mm long, 70 12. Peronodoris rebde ri, new species, mm broad, and 58 mm high ; its shell measures figs. 27-30 45 by 24 mm. The animals are nearly smooth, Subfamily Discodoridinae with scarce warts. 13. Sebadoris crosslandi (Eliot) 14. TaYl/va ketos jl/va, new sub D olabrifera dolabrifera (Rang, 1828) species, figs. 31, 32 RANGE : Circumtropical and circumsubtropical, Subfamily Platydoridinae (Arginae) but not yet recorded from the American Pacific 15. Platydoris scabra (Cuvier) coast. 16. Pttpsikl/s pingl/is, new genus, new species, figs. 33-39 COLLECTING STATIONS: Society Islands: Wof Tribe Phanerobranchia Point Tiva, Huahine, white sand and algae, Superfamily Nonsuctoria (family Gym depth 1.3 m, February 18, 1965, R. L. Sixberry, nodorididae) 4 specimens (USNM 576153) ; Mitirapa, Tahiti, 17. Gymnodoris citrina (Bergh) , fig. September 2, 1964, R. L. Sixberry, 1 specimen 40 ( USN M 576009 ). 18. Gymnodoris striata (Eliot), fig. DESCRIPTIVE NOTE: Due to the subequal 41 prongs of the radular teeth, Pruvot-Fol (195 4, Suborder Porostomata p. 13, fig. 15 on p. 12) considers her spec Family Dendrodorididae imens from Tahiti as possibly distinct from D. 19. D endr odoris nigra (Stimpson) dolabrifera. The present material also has such 20. Dendrodoris denisoni (Angas), radular teeth, but, as previously mentioned fig. 42 (Marcus and Burch, 1965, p. 244), they do not Family Phyllidiidae characterize a geographic form but occur also in 21. Phyllidia (Ph yllidia) tnla, new material from the Indian Ocean (Eales, 1944, species, figs. 43- 47 fig. 9A). 22. Phyllidia (Phyllidiella) alllllllata Gray, figs. 48-49 Srylocbeilus longicauda (Quoy and Gaimard, 23. Phyllidia (Phyllidiella) variabilis 1824) (Collingwood), figs. 50-52 RANGE: Circumtropical and circumsubtrop 24. Phyllidia (Phyllidiella ) soria, ical; also from the Gulf of California (Marcus new species, figs. 53, 54 and Marcus, 1967, p. 159). D olabella anricularia (Lightfoot, 1786) COLLECTING STATION : Society Islands: Pa Dolabella scapnla (Montagu) Engel, 1942, penoo, Tahiti, reef flat, R. L. Sixberry, 3 spec pp . 207-234, figs. 6-16; Marcus and Mar imens ( USNM 576000). cus, 1960, pp . 894-896, figs. 32-35. DESCRIPTIVE NOTE: The animals have the RANGE : Indo-Pacific from the Red Sea and longitudinal black streaks and ocellar spots East Afri ca to Japan and Easter Island ; also typical of the species. Op isthobranchs from South Pacific-MARCUS AND MARCUS 157 Oscanius grandis (Pease, 1868) DESCRIPTION : The preserved animals from Figs. 1- 7 Tahiti are 75 and 65 mm long, 50 and 58 mm Pleurobrancbns grandis Pease, 1868, pp. 78 broad, and 10 and 11 mm high ; the specimen 79, pi. 10, fig. 2. from Raiatea is larger, 80 mm long, 60 mm Oscanius grandis Pilsbry, 1896, pp. 218 , 219, broad, and 20 mm high. Its foot is 70 mm long, pi. 45, fig. 1. 50 mm broad; the notum , 65 by 60 mm. The Pleurobrancbns (Sm ania) grandis Vayssiere, shell (Fig. 2) lies in fron t of the middl e, and 1898, pp . 375-377, pi. 15, fig. 24. it is 8.4 mm long, 6.0 mm wide in the long er animal from Tahiti, pink and with growth lines. RANGE: Society Islands. The periostracum which fell off fro m the drying shell showed spiral lines, mainly in the apical COLLE CTING STATIONS: Society Islands : Pa part. para, 40 km south of Papeete, Tahiti, in black sand and und er coral, 196 3, R. L. Sixberry, 2 The especially well preserved specimen from Raiatea (Fig. 1) is light brown with darker specimens ( USNM 576013 ) ; northeast tip of Motu Iriru, Raiatea, level sandy area, collected centers in the dorsal polygons, and with sharply at night, March 8, 1965 , R. L. Sixberry, 1 delimited dark brown spots. Two big spots lie to the sides in front, a larger one farther back specimen (USNM 675467) . in the middle, and one on the tail passes as a triangular fleck onto the foot. Smaller notal spots are seen in Figure 1. Th e rhinophores, the lapp ets around the genital apertures, the gill , and the inner part of the hyponotum are dark brown. The pigment of the hyponotum con tinues onto the back of the foot. The broad and folded penis is light, the sale yellowish grey without flecks. Th e notum bears polygons up to 9 mm in diameter, separated fro m each other by ridges. They are flat except for a central, generally darker knob. The knobs are surrounded by an inner ring of ridg es connected to the outer ridge by radial ones. Small knobs lie in the area be tween the two rings. Where the notum is some what contracted, irregular concentric bulges appear around the central knobs, and the limits of the polygons are marked as furrows. Spicules or vestiges of spicules were not found. The anterior pedal border is bilabiate; the pink upper lip is slightly shorter and thicker than the lower lip. The posterior pedal gland lies in the dark area and is not very distinct. The frontal veil is small, fur rowed laterally, and blackish brown at its base. The rolled rhino phores lie near one another. The gill is about FIGs. 1- 7. Oscanius grandis, 1, Preserved animal half the length of the body. Of its 20 to 22 from Raiatea. 2, Shell. 3, Jaw platelets. 4, Innermost radul ar tooth. 5, Radu lar tooth from middle of half plumules on either side of the rhachis, 7 to 10 row. 6, Outermost radular tooth . 7, Diagram of re are free from the branchial membrane. The productive organs. main rhachis and the secondary rhachises bear ( a ) Ampulla, (b) bursa, (d) male duct, (m) fe tub ercles. The anus is located over the end of male gland mass, ( 0) inner oviduct, (p ) penis , ( q ) prostate, (1') prostatic duct, (s) spermatocys t, the branchial membrane, Bourne 's gland be ( v) vagina. tween the genital lappets and the beginning of 158 PACIFIC SCIENCE, Vol. 24, April 1970 the gill. The female aperture opens between sis from Hainan with O. grandis. The sculpture two reddish lips. of the two species is similar, but the color of The buccal armature was examined in the back and foot gland and the lanceolate jaw larger animal from Tahiti.