Family Chondropominae

PROCEEDINGS OF THE UNITED STATES NATIONAL MUSEUM issued i^^lVyl QSi^il h the SMITHSONIAN INSTITUTION U. S. NATIONAL MUSEUM Vol.89 Wa.hington:194I No. 3096 THE CUBAN OPERCULATE LAND MOLLUSKS OF THE FAMILY ANNULARIIDAE, EXCLUSIVE OF THE SUB- FAMILY CHONDROPOMINAE By Carlos de la Torre and Paul Bartsch In the introduction to our monogi'aph on "The Cuban Operculate Land Shells of the Subfamily Chondropominae" ^ we gave a general historic account of the work preceding our effort. The statements made there apply equally to the present paper. We are considering here the remaining subfamilies of the family Annulariidae known to inhabit Cuba, namely, the Rhytidopominae, Adamsiellinae, and Annulariinae. The differentiations which the members of this family have under- gone in Cuba are extraordinary and offer a field for speculation and theorizing unequaled in any other part of the world. We are con- fining our attention to the taxonomic side of the question, merely calling attention to demonstrable facts without expressing personal opinions regarding the speculative questions involved. Following Henderson and Bartsch,^ we are recognizing four subfamilies in Annulariidae, basing our divisions upon opercular characters. All annularids have an operculum, consisting of a chondroid basal plate of a varying number of whorls. The whorls composing this plate may be simple, that is, without further differentiation, or they may have a granular calcareous deposit, or bear ribs or lamellae or > Proc. U. S. Nat. Mus., vol. 85, pp. 193-403, figs. 71-101, pis. 7-39, 1938. « Proc. U. S. Nat. Mus., vol. 68, pp. 49-82, 1920. 131 132 PROCEEDINGS OF THE NATIONAL. MUSEUM Vol.89 combinations of these characters, which easily fall into four categories here recognized as subfamilies. The first of these subfamilies, the Chondropominae, has a simple chondroid plate consisting of a number of whorls, which usuallj^ have more or less of a finely granular calcareous deposit on the outside. In the second, the Rhytidopominae, the whorls bear a calcareous desposit, which may consist of simple, retractively curved riblets that may remain distinct or may become fused at the edge into a solid plate. In the third, the Adamsiellinae, which is poorly repre- sented in Cuba, the upturned outer edge of the preceding whorl is strengthened and built into a strongly elevated lamella by the inner edge of the succeeding turn. This lamella has no ribbing or buttress- ing. In the fourth subfamily, the Annulariinae, the whorls of the operculum are provided with a strong calcified lamella, which rises from the inner edge of the turns; it may be vertically placed or re- flected to parallel the basal plate, and it may be smooth or ribbed. It is usually connected with the basal plate by reenforcement. The presence or absence of breathing devices of definite type is not restricted to any of the subfamilies; they find service in all of them. These breathing devices vary from a mere notch near the posterior angle of the aperture to a puncture in the parietal wall, which puncture may be further emphasized by having a siphon built on the outside of it. This siphon even may be prolonged and deflected tlii'ough the suture to the umbilicus, which it closes, and breathing is thus effected through the hollow axis of the shell and through the decol- lated apex. Or, the columellar wall may have a slit at some distance from the peristome, through which breathing communication is estab- lished with the hollow axis. Another feature, the taxonomic value of which we have not defi- nitely decided upon in this work, is the nuclear sculpture. The embryonic whorls, usually about two, are microscopically granulose, that is, smooth under hand-lens magnification. In two groups, Limadora and Limadorex, they bear strong definite sculp tm-e; in the first this is thimble pitting, and in the second thimble pitting and spiral threads and axial ribs. In the rest of the shell characters they are not unlike other groups, but in these embryonic features they are widely at variance with the other members of the family. The three subfamilies here discussed confirm our findings in the Chondropominae: that Cuba represents three centers of development, namely, an eastern, a central, and a western province. Where we have referred in the keys to closely spaced or axial riblets, the statement refers to the later whorls. We have used brackets around certain names to indicate that the original describer gave credit for the species to the one whose name appears in brackets, for example ([Gundlach] Pfeiffer). CUBAN ANNULARIIDAE—TOKRE AND BAKTSCH 133 In conclusion, we wish to express again our thanks and appreciation to all the institutions and individuals aclmowledged in our former paper. Without their continued help this monograph would have been incomplete. Subfamily Rhytidopominae Henderson and Bartsch 1920. Rhytidopominae Henderson and Bartsch, Proc. U. S. Nat. Mus., vol. 58, pp. 64-65. Shell ranging from elongate-conic through ovate to turbinate. Axial ribs are always present; they may vaiy from mere threads to lamellae; they may terminate simply; they may become expanded at the summit into broad denticles or even fused there into hollow cusps or tufts. Spiral threads may be present on spire, base, and umbilicus, or m the umbdicus only, or they may be even entirely absent. The last whorl may be adnate or solute and the mnbilicus may be open or closed. The operculum has as a basis a chondroid plate composed of several whorls, the outer surface of which bears numerous, retractively slanting, raised lamellae, which vary greatly in strength in the different genera. They may extend completely across each whorl or they may cover only a part of it, as in Opistho- siphon. These lamellae may or may not be fused on their inner and outer termuaation. They may be rather distantly spaced or they may be almost fused at their edge. Special devices for breathing when the operculum closes the shell may be present or absent. They show an enormous range of specialized development, which will be discussed under each genus. Type genus.—Rhytidopoma Sykes. KEY TO THE GENERA OF THE SUBFAMILY RHYTIDOPOMINAE Breathing device present. Breathing siphon present. Siphon complete. Lamellae of the operculum extending completely across the whorl Opisthocoelicum Lamellae of the operculum not extending completely across the whorl. Lamellae of the operculum fused at their inner and outer edge to form a spiral keel. Lamellae between the inner and outer keel as high as the keels Torrella Lamellae between the inner and outer keel not as high as the keels, but concave at the free edge Rhytidoponia Lamellae of the operculum not fused at their outer edge Opisthosiphon Siphon incomplete Dallsiphona . 134 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.89 Breathing siphon absent. Breathing puncture present. Breathing pore communicating with the space behind the withdrawn operculum Xenoporaoides Breathing pore communicating with a channel at the posterior angle of the aperture connecting with the hollow axis somewhere behind the peristome Rhytidothyra Breathing device absent. Last whorl of operculum covered by an overarching dome Xenopoma Last whorl of operculum not covered by an overarching dome.. Parachondria OPISTHOCOELICUM, new genus In this genus the operculum resembles that of Rhytidothyra, i. e., the reenforcements on the outside consist of strongly raised, retractively curved lamellar ribs, which extend completely across the turns (they are not separated by a channel as they are in Opisthosiphon). A siphon is present immediately behind the peristome, at the posterior angle of the aperture. This siphon bends into the suture, and it connects with the umbilicus by a channel behind the expanded outer peristome. Type.—Opisthocoelicum (Opisthocoelicum) opisthocoele, new species. The genus appears to be confined to the provinces of Santa Clara and Camagiiey. We are recognizing three subgenera, which the following key will help to distinguish: KEY TO THE SUBGENERA OF OPISTHOCOELICUM Operculum too large to be withdrawn into the shell Opisthocoelex Operculum not too large to be withdrawn into the shell. Axial ribs gathered into hollow tufts at the summit Opisthocoelops Axial ribs not gathered into hollow tufts at the summit Opisthocoelicum Opisthocoelex, new subgenus In this subgenus the inner peristome is much exserted and the operculum is much too large to be withdrawn into the shell, which it merely caps. The retractively curved lamellae on the outside of the operculum are fused laterally to form an almost continuous plate, resembling somewhat the operculum of Colohostylus of Jamaica. The breathing device is the same as in typical Opisthocoelicum. In the present subgenus the axial ribs are thickened at the summit, but they are not gathered into tufts. Type: Opisthocoelicum (Opisthocoelex) paradoxum (Torre and Henderson) : CUBAN ANNULARiroAE TORRE AND BARTSCH 135 KEY TO THE SPECIES OF THE SUBGENUS OPISTHOCOELEX Axial ribs closely spaced paradoxum Axial ribs distantly spaced simulans OPISTHOCOELICUM (OPISTHOCOELEX) PARADOXUM (Torre and Henderson) Shell elongate-ovate, pale yellow, unicolor or marked by narrow, feebly interrupted spiral bands of brown, the elements of which are arranged in both axial and spiral series. Nuclear whorls 2, inflated, strongly rounded, microscopically granulose. The postnuclear whorls are well rounded, the early ones marked by lamellar, scalloped, distantly spaced axial ribs. These ribs become more approximated on the middle turns and quite closely spaced on the last whorl, where they are separated by spaces not so wide as the ribs. The scallops on the whorls are more strongly developed at the summit than at the periphery, and on the early whorls the scallops at the periphery interlock with those at the summit of the succeeding turn. The scallops are absent on the last turn. Suture well impressed. Periphery strongly rounded.

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