Chitons and gastropods (Haliotidae through Adeorbidae) from the western Pacific Islands

Abstract

Cenozoic mollusks from seven island groups in the western Pacific are treated systematically. The islands form a broad belt spreading 4,000 miles across tropical latitudes from the Mariana Islands and Palau on the northwest through the Marshall, Ellice and New Hebrides groups to Fiji and Tonga on the southeast. Each of the island groups has a section of Quaternary limestones and all except the Ellice group are known to have a Tertiary sequence as well. The known Tertiary in all island groups, except that in the New Hebrides, extends back as far as the Eocene. No Paleocene rocks have been recognized. Two hundred and eight species and subspecies are described. These include representatives of 3 families of chitons and 16 families of gastropods (Haliotidae through Adeorbidae). Three new subgenera of gastropods are described: Vitiastraea (subgenus of Astraea), Subditotectarius (subgenus of Tectarius), and Ailinzebina (subgenus of Zebina). Sixty-seven new species and five new subspecies are described. The species discussed in the present report comprise approximately one-sixth of available collections. About three-fourths of the new forms were recovered from the drill holes in the Marshall Islands; the remainder, from outcrop samples, are divided almost equally between Palau and Fiji. A few of the new forms from the Marshall Islands also occur in Palau and Fiji. The richest and most widespread assemblages are Miocene (Tertiary / and g). Most of the mollusks are reef associated. Many, notably those of the limestones in the deep drill holes of the Marshall?, occur in beds that were deposited in lagoons; some species occur in beds that were accumulated on tidal flats; a few species lived in fresh or brackish waters. The assemblages of fossil mollusks, like those living in the area today, are Indo-Pacific in general aspect. The strongest discernible ties are with living and fossil faunas of tropical Indonesia, rather than with faunas from more southerly areas (southern Australia and New Zealand) or more northerly areas (the Ryukyu Islands and Japan). Thirty-throe of the des-ribed species that still live in the island area have been there at least since late Tertiary time. Of this group, the shells of 25 were recovered from Marshall Island drill holes, those of 10 from outcrops in Fiji. A few species that lived in the island area during the Tertiary are now living only in other parts of the Indo-Pacific region. Numerous living Indo-Pacific species had close relatives, some perhaps ancestral, in the island area during the upper Tertiary. In the Miocene of Bikini is a species of Pisulina, a genus known previously only from a few species living near India and Ceylon. The neanvt relatives of a lower Miocene CtjniNcn of Eniwetok live off the Capo of Ciood Hope, South Africa, tichtzachitott, the reef chiton that lives today in the Philippines and northern Australia, had representatives in the Marshall Islands and Palau during the Miocene. Ties between the island area and the Americas are suggested, but they are less impressive t...

Oligocene and Early Miocene gastropods from Kutch (NW India) document an early biogeographic switch from Western Tethys to Indo-Pacific

“…Phasianella teschi Martin, 1916 (treated as a synonym of the extant Phasianella aethiopica Philippi, 1853by Hoek Ostende et al, 2002 from the Early Miocene of Java differs clearly in its higher spire and the strongly convex spire whorls. Two Phasianella opercula from the Miocene of Eniwetok described by Ladd (1966) are incomparable with the Indian material.…”

Two new pandalid shrimps and the discovery of the second specimen of the rare hippolytid shrimpLeontocaris bulgaTaylor & Poore, 1998 (Crustacea, Decapoda) from the Mozambique MAINBAZA Cruise

“…I have no doubt that the Réunion samples belong to a single species and consider the number of spiral cords on the penultimate whorl (four or five) to be a variable character. There is evidently similar variation in the number of spiral cords on the base (6-8 The holotype of H. xeniolum was collected in shallow water (-9 m) and similarly the overall facies of the fauna at the type locality of H. waiwailevensis is that of a shallowwater, lagoonal system (Ladd 1966(Ladd , 1982. The depth at which the dredged material from Réunion was obtained (-110-340 m) would thus seem to be anomalous.…”

“…The only local species with which it might be confused is P. konos, but that species is smaller, never has such strongly developed peripheral projections, has weaker basal cords and more widely spaced axial pliculae on the apical whorls. Turcica (Perrinia) mor risoni Ladd, 1966 from the Marshall Islands, is smaller, less elevated and has much more obvious dentition inside the outer lip. Tomlin (1927) followed by Lamy (1938) synonymised Tectaria armata Issel, 1869 from the Red Sea, with the present species.…”

Pickworthiidae and Aqabarellidae New Family (Caenogastropoda, Mollusca) of Aqaba, Jordan: Their Larval Shells and Remarks about Their Evolution and Relation

“…Sansonia kenneyi (Ladd, 1966) 3). The fossil species from the Oligocene has a 1 mm high shell consisting of three whorls of the teleoconch of quite the same ornament as in Sansonia cebuana, but the protoconch has 2.5 whorls and ornament of spiral ribs without axial components on the larval whorls.…”

“…Regarding shell shape and concave sutures Microliotia pumilis is similar as well but differs by a little wider shell and finer ornament ( [9], figs. [22][23][24][25][26]. The type to the genus Discrevinia balba has the last whorl of its shell covered by spiral ribs, while earlier whorls resemble those of Discrevinia satondae.…”