MALACOLOGIA, 1970, 10(1): 181-223 SOME GASTROPODS FROM MADAGASCAR AND WEST MEXICO ^ Eveline du Bois-Reymond Marcus ^ and Ernst Marcus^ ABSTRACT This paper deals with 43 species of marine gastropods, mostly opistho-branchs (but also 1 lamellariacean and 3 onchidiaceans) from Madagascar and from the Gulf of California. Anatomical descriptions are given for the various species. Three species were recognized to be common to both collections; these represent taxa occurring in circumtropical-warm seas. The following new species are described: Smaragdinella kirsteueri. Stiliger {Stiliger) erbsus, Hypselodoris regina and Noumeaella isa (from Madagascar), and Elysia vreelandae (from West Mexico). The new name Stiliger (S.) raorum substitutes S. (S .) nigrovittatus Rao & Rao, 1963. The opisthobranchs of Mada-gascar belong to the rather homogeneous Indo-Pacific reef fauna, while those from the Gulf of California live in areas largely devoid of coral reefs, but containing an admixture of Panamic and American temperate Pacific faunal elements. INTRODUCTION The present paper treats 30 species from Madagascar as Part XI of the Austrian Indo-west Pacific Expedition 1959/1960, and 13 species from the Gulf of California. Five new species are described, of which 4 are from Mada-gascar. Benthonic animals of shallow water from these regions are separated by Ekman's East Pacific Barrier (Emer-son, 1967). Only 3 species, which occur in all warm seas, are represented in both collections. Comparative morpho-logical studies of opisthobranchs indi-cate that many species, especially nudi-branchs, have extensive geographical ranges. Several species are known to occur in more than one zoogeographical province and some species of nudi-branchs are apparently circumtropical in distribution. Therefore, a combined publication of zoologically allied, though geographically separate collections, fa-cilitates faunal comparisons. The opis-thobranchs of Madagascar belong to the rather homogeneous Indo-Pacific reef fauna, but those from the Gulf of Cali-fornia live in areas largely devoid of coral reefs. There, species of re-stricted or wide distribution in the Panamic faunal province meet with others of the American temperate Pa-cific fauna. The Panamic province is related to the Caribbean, and the Amer-ican temperate Pacific fauna includes Japanese elements. Although most of the species in the present collections are opisthobranchs, the first species treated belongs to the Lamellariacea. These are traditionally collected and studied together with opis-thobranchs. Our 4 last species are Onchidiacea. Van Mol (1967) re-estab-lished the subclass Pulmonata in a re-cent study of the cerebral ganglion in Basommatophora, Stylommatophora, and 1 Published with the cooperation of the Institute of Malacology. ^Address: Caixa Postal 6994, Sao Paulo, Brazil. ^Professor Emeritus of Zoology, University of Sao Paulo. Deceased June 30, 1968. (181)
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