New land mollusks from Madagascar and Mexico
FIELDIANA · ZOOLOGY
CHICAGO NATURAL HISTORY MUSEUM
New Land Mollusks from Madagascar and Mexico
Curator Emeritus, Division of Lower Invertebrates
The material described in this paper was sent to me by Mr. Allyn G. Smith of the California Academy of Natural Sciences. As the shells were collected in areas outside of the scope of said institution, Chicago Natural History Museum was kindly allowed to keep the unique specimens, the types of two of the three species described herein; there are several paratypes of the third, and some of these will be returned to the Academy of Natural Sciences.
Malarinia, new genus
An apparently new genus of Cyclophoracea, looking somewhat like a slender Cochlostoma of the subgenus Turritus. The only known species, which thus automatically becomes the type species, will be described below under the name of Malarinia hova. In this description, additional characters of the genus Malarinia will be mentioned.
Malarinia hova, new species. Figure 10.
Diagnosis.—A rather small cyclophoraceous shell, slender, with ventricose whorls which are densely costulate, and with an aperture measuring about one fourth of the entire height.
Description of type.—Shell rimate, slender, turreted, with 7½ whorls, which are rather convex and hence separated by a deep suture, regularly growing; they are densely and sharply costulated, the ribs being crossed by hardly visible spiral lines; the last whorl ascends somewhat toward the aperture, which is almost circular, a little bit angularly produced above on the right; the peristome is continuous and double. Operculum unknown.
Measurements: Height, 6.19 mm.; width, 2.31 mm.; height of aperture, 1.58 mm.; width of aperture, 1.3 mm.
Type.—Chicago Natural History Museum No. 106701. Collected in Chutes de la Mort, Madagascar, by E. S. Ross, November 10, 1959.
Remarks.—The affinities of this new form in the super-family of Cyclophoracea are still obscure; despite some similarities with the Cochlostominae, a close relation with the Diplommatinae seems more probable.
|Fig. 10. Malarinia hova, new gen.|
and sp. CNHM No. 106701, front
view; about × 5.
Bulimulus (Rhabdotus) fonsecanus, new species. Figure 11, a, b.
Diagnosis.—A medium-sized, rather thin shell, pinkish white, smooth, elongate ovate, covered rimate, with the aperture provided with a thin, reflected lip.
Description of type.—Shell of medium size, elongate conic, rather thin, pinkish white, with no traces of sculpture but for slight incremental lines. Seven whorls, of which the three first ones grew slowly and regularly, the last ones more rapidly; the last descends slightly toward the aperture. The obesity of the whorls increases toward the aperture; the suture is simple. The apical whorls appear smooth, most probably due to wear. Aperture elongate elliptical, about 4/9 of the height of the shell; the lip is reflected and forms a rather wide, white peristome, which covers the deeply rimate umbilical region; the ends are hardly converging, but are united by a rather thick, white callus.
Measurements: Height, 27.5 mm.; width, 15.0 mm.; height of aperture, 13.5 mm.; width of aperture, 9.5 mm.
Type.—Chicago Natural History Museum No. 106702. Collected on the Gulf of Fonseca, San Salvador or Nicaragua. Collector unknown; received from the California Academy of Natural Sciences in San Francisco.
Fig. 11. Bulimulus (Rhabdotus) fonsecanus, new sp. CNHM No. 106702, type, front and back views; about × 2.
Relationships.—The species here described seems to be most closely related to Bulimulus (Rhabdotus) baileyi Dall from the Mexican state of Sonora. The fact that the new fonsecanus does not show any surface sculpture, as baileyi does, may be due to the fact that the type, the only specimen at hand, has been collected dead in a rather worn down state. However, there are characteristic differences between the two species: fonsecanus has seven whorls instead of the five to six in baileyi, and the shape of the aperture is different; in baileyi the ends of the peristome converge without a noticeable callus between them, while in fonsecanus the ends of the peristome do not approach each other and are united by a conspicuous callus.
Remarks.—The region of the Gulf of Fonseca, the locality of this new species, is much farther south than any other known locality of a member of the subgenus Rhabdotus.
Polygyra (Erymodon) hertleini, new species. Figure 12, a-c.
Diagnosis. A depressed, slightly angulated shell with a low spire, the surface almost densely ribbed by regular growth lines, the umbilical region with a perforate umbilicus, the aperture lipped, with a concave lamella and two tubercular teeth, the parietal wall bearing a low, thin lamella with a short, V-shaped hook.
Description of type.—Shell depressed, spire low, periphery slightly shouldered near the suture, base convex; perforately and narrowly umbilicated, the umbilicus rapidly enlarging at the last whorl to about one-third of the diameter of the shell. Surface light-colored, densely, regularly, and finely ribbed, the ribs vanishing toward the umbilicus; no spirals between the ribs. Whorls 6¾, rather convex, regularly growing, the periphery at the shoulder above the middle; the last whorl abruptly descending near the aperture, deeply and narrowly constricted behind the lip.
Fig. 12. Polygyra (Erymodon) hertleini, new sp. CNHM No. 106703, type; views from above, below, and side; about × 2.
Aperture oblique, crescent-shaped, thinly lipped. Outer lip narrowly expanded, bearing a concave lamella with a denticle at its lower end; basal lip with a marginal, round denticle. Parietal wall bearing a lamella with a hardly visible hook-like appendix at its inner end.
Measurements: Diameter, 13.2 mm.; height, 6.3 mm.; diameter of aperture, 4.5 mm.; height of aperture, 4.0 mm.; diameter of unbilicus, 3.5 mm.
Type.—Chicago Natural History Museum No. 106703. Collected on Tenecatita Bay, Jalisco, Mexico, about 1½-2 miles up trail, by Leo G. Hertlein, February 15, 1932.
Additional material.—Four more specimens with the same data as the type are at hand. One of these paratypes is Chicago Natural History Museum No. 106704, and three are in the California Academy of Sciences in San Francisco, No. 27212. All these specimens agree perfectly with the type, differing slightly only in the measurements: diameter, 13.2-14.0 mm.; height, 6.6-7.3 mm.
Relationships.—There can be no doubt that this new species has its closest relative in Polygyra (Erymodon) matermontana Pilsbry. My friend and colleague, Dr. Alan Solem, was kind enough to compare my new species with the specimens of Pilsbry's species matermontana in the Philadelphia Academy of Sciences, and he found them different enough from its subspecies jaliscoensis and this to warrant its description as a novelty. According to Dr. Solem, the species hertleini differs from the matermontana group by being larger (13.2 mm. against 9.5-12 mm.), being always shouldered at the periphery, showing stronger ribs, having a wider umbilicus (one-third of diameter against one-fifth), having 6¾ whorls against 5¾, and almost entirely lacking the inner branch of the V-shaped lamella on the parietal wall.
- From "Malagasy" and "Arinia."