Revision of the American Pupisoma species (Gastropoda: Pupilloidea)

The American species of Pupisoma Stoliczka (Gastropoda: Pupilloidea) are revised. Five species are recognized. Pupisoma puella Hylton Scott has been synonymized with P. dioscoricola (C. B. Adams). This species occurs from southern USA through the Caribbean and Central America to the Galapagos Islands and to southern Brazil and northern Argentina. Pupisoma galapagorum Pilsbry, P. bailyi Pilsbry, and P. latens Hylton Scott have been synonymized with P. comicolense H. B. Baker. This species is distributed from Mexico to the Galapagos Islands, southern Brazil, and northern Argentina. Pupisoma costulata sp. n. from Andean forests in Colombia is described as new. The range of P. macneilli (Clapp) extends from southern USA through the Caribbean and Central America to southern Brazil and northern Argentina. A neotype has been designated for P. mediamericanum Pilsbry. Pupisoma michoacanense Pilsbry is a synonym of this species. This species occurs from Mexico to Colombia and on Jamaica.

lines that are usually considered to belong to Ptychopatula (see e.g. Vermeulen and Raven 1998) with Pupisoma sensu stricto. Moreover, the appendix of P. orcula (Benson, 1850), the type species of Parazoogenetes, is also smaller than in P. comicolense and P. mediamericanum and also has no retractor muscle (Habe 1956).
The relationships of the second group of Pilsbry's classification, which includes the American species with the exception of P. dioscoricola (C. B. Adams), are still uncertain. They should not be included in Ptychopatula, because they differ from that group in having a large penial appendix with retractor (Baker 1928) and in the absence of distinct spiral lines (the long kidney of P. comicolense and P. mediamericanum should not be overvalued, because it might simply be a consequence of the higher whorl count of these species; the kidney of P. macneilli (Clapp) might be shorter). Whether they are closely related to the Old World Pupisoma sensu stricto species which are anatomically unknown is questionable. An alternative possibility would be that Pupisoma is polyphyletic and that the American group is neither related to Pupisoma sensu stricto nor to Ptychopatula, but is closely related to the American Bothriopupa Pilsbry which it resembles except in the lack of dentition of the aperture (see Pilsbry 1920). Because of these uncertainties Pupisoma is retained preliminarily in the wide sense.

Shell (Figures 1, 2)
Globose-conical; apex obtuse; body whorl with unequal growth lines crossed by fine incised spiral striae, sometimes with additional low riblets; upper whorls irregularly granulated; corneous; shining; subtranslucent; 2.5-3.25 inflated whorls separated by a deep suture; body whorl slightly descending towards the aperture, basally rounded; aperture truncaterounded, edentate; peristome neither expanded nor reflexed nor thickened; columellar margin triangularly dilated, more or less covering the narrow umbilicus. Shell measurements and ratios are listed in Tables I and II.

Remarks
Pupisoma dioscoricola can easily be distinguished from the other American Pupisoma species by its distinct spiral striae and its larger first whorls.
Mö llendorff (1899) and Haas (1937) failed to note that there are two species among the type series of P. americanum Mö llendorff, 1899. The lectotype designated by Haas (1937) and some of the paralectotypes belong to the form of P. dioscoricola with distinct riblets, later called P. dioscoricola insigne Pilsbry, 1920, the other paralectotypes belong to P. macneilli. Specimens with distinct riblets occur scattered throughout the range of P. dioscoricola and sometimes even sympatrically with the typical form. Therefore, the form with distinct riblets cannot be considered a geographical subspecies.
Pupisoma puella Hylton Scott, 1960 was based on a single specimen which differs from P. dioscoricola insigne supposedly in the more regular spacing of the riblets. Hylton Scott (1960) separated P. puella from P. dioscoricola insigne mainly because of the great distance between the type locality of the latter in Texas and the occurrence of the former in Argentina. However, specimens with distinct riblets occur also in the intervening regions, e.g. also in Guyana and Ecuador. There is no reason to consider P. puella to be specifically distinct.
The anatomy of P. dioscoricola has been described by Tillier (1980). The specimens recorded as P. dioscoricola from Dog Island by Haas (1960) do not belong to Pupisoma. Pilsbry (1920) has already questioned whether P. orcula (Benson, 1850), that is distributed throughout the Old World tropics from Africa to East Asia, Australia and even to some Pacific islands, can be separated from the American P. dioscoricola (see also Solem 1989). A comparison of American specimens with material from Africa also did not reveal any conchological differences. Thus, P. orcula (Benson, 1850) can be considered a synonym of P. dioscoricola unless future genetic studies show that Old World and New World populations form separate units.

Distribution (Figure 6)
Pupisoma dioscoricola is a circumtropical species (given that P. orcula is a synonym). Pupisoma dioscoricola originated probably in the Old World, because all other Ptychopatula species are restricted to the Old World tropics. However, given its wide distribution in the Americas, it is unlikely that P. dioscoricola has been introduced into the New World only by humans.
Pupisoma dioscoricola is one of the most widespread snails in tropical and subtropical America occurring from the southern USA through the Caribbean and Central America to the Galapagos Islands and to southern Brazil and northern Argentina. It is most frequent in lowland forest, but has been found up to 2100 m altitude.

Pupisoma (Pupisoma) Stoliczka, 1873
Diagnosis Shell without distinct spiral lines and penis with large appendix with retractor.

Shell (Figures 3-5)
Globose-conical or oblong-conical; apex obtuse; with irregular growth lines, without incised spiral striae; corneous; usually brightly shining; subtranslucent; 2.75-3.5 inflated whorls separated by a deep suture; body whorl hardly or slightly descending towards the aperture, basally rounded; aperture truncate-rounded, edentate; peristome neither expanded nor reflexed nor thickened; columellar margin slightly dilated, hardly or partly covering the umbilicus; umbilicus taking 2-15% of the shell breadth. Shell measurements and ratios are listed in Tables I and II.

Remarks
Pupisoma comicolense differs from P. mediamericanum in the on-average larger (diameter of the first two whorls of P. comicolense 0.90-1.05 mm; diameter of the first two whorls of P. mediamericanum 0.80-0.95 mm), smoother shell (see also P. mediamericanum).
Specimens with 3.5 whorls are oblong-conical, whereas specimens with three or fewer whorls are globose-conical. In oblong-conical specimens the umbilicus usually takes less than 10% of the shell breadth, whereas in the globose forms it can be wider. Pupisoma latens Hylton Scott, 1960 from Argentina is such a globose form with a comparatively wide umbilicus. In an extreme form from San Miguel de Tucumán the umbilicus occupies 11-15% of the shell breadth. The identity of the widely umbilicated forms from Argentina with P. comicolense should be checked with molecular genetic markers. Preliminarily, they are considered to be conspecific with P. comicolense, because there are apparently intermediate specimens between the extreme forms. No constant conchological differences have been found between P. galapagorum Pilsbry, 1934 from the Galapagos Islands, P. bailyi Pilsbry, 1934 from Mexico, and P. comicolense.
The anatomy of P. comicolense has been described by Baker (1928).

Distribution (Figure 7)
Pupisoma comicolense is distributed in Central and South America from Mexico to the Galapagos Islands, southern Brazil, and northern Argentina. It is most frequent at medium and higher altitudes. Its altitudinal range extends from about 100 to 2600 m altitude.

Diagnosis
Pupisoma costulata differs from all other Pupisoma species in the conical shell with more whorls, a flattened base, and coarse growth-wrinkles. In shell shape and size it is most similar to P. mediamericanum.

Remarks
Pupisoma costulata occurs sympatrically with P. comicolense. The range of P. costulata overlaps that of P. mediamericanum, the conchologically most similar species.

Etymology
The species is named after its finely ribbed (Latin costulatus, used as an adjective) shell.

Remarks
Pupisoma macneilli differs from P. mediamericanum in the on-average lower shell with a wider umbilicus and fewer whorls. It differs from P. comicolense in the smaller (diameter of the first two whorls: 0.75-0.90 mm; in P. comicolense: 0.90-1.05 mm), dully shining shell with distinct growth lines and irregular impressions.
No constant differences were found between P. minus Pilsbry, 1920, the type locality of which is in Florida, and P. macneilli (Clapp, 1918) described from Alabama. Thus, I agree with Hubricht (1985) that these nominal species are synonyms.
The specimens recorded as P. minus from St Eustatius by Haas (1960) are P. dioscoricola.
Distribution ( Figure 14) The range of P. macneilli extends from the southern USA through the Caribbean and Central America southwards to southern Brazil and northern Argentina. It is most frequent at medium and higher altitudes. Its latitudinal range extends from about 100 to 2600 m altitude.

Remarks
Pupisoma mediamericanum differs from P. macneilli in the on-average higher shell with a narrower umbilicus and more whorls. Note, however, that the umbilicus of specimens of P. mediamericanum with more than 3.5 whorls can become moderately wide. Pupisoma mediamericanum differs from P. comicolense in the on-average smaller (diameter of the first two whorls of P. mediamericanum 0.80-0.95 mm; diameter of the first two whorls of P. comicolense 0.90-1.05 mm), more distinctly striated shell. Especially in southern Central America there are large forms of P. mediamericanum which are difficult to distinguish from P. comicolense. The spire of P. comicolense becomes broader more quickly than that of P. mediamericanum so that P. comicolense is initially more globular, whereas P. mediamericanum is more conical. Pilsbry (1920) cited ''Type and paratypes'' of P. mediamericanum Pilsbry from Orizaba (ANSP 28270), but did not note any characteristics of the ''type'' and did not indicate the ''type'' in the collection (P. Callomon, ANSP, in litt.). He mentioned also a second sample from Chama, Guatemala. Baker (1963) designated a lectotype from the sample ANSP 28270 from Orizaba and mentioned ''Third set of dimensions'' to characterize the lectotype. However, the third set of dimensions given by Pilsbry (1920) refers to a specimen from Chama. The specimen labelled as lectotype of P. mediamericanum Pilsbry (ANSP 28270a) is not a Pupisoma and its measurements (D51.25 mm, H51.35 mm) are smaller than any of the measurements given by Pilsbry (1920) for P. mediamericanum. Obviously, this specimen cannot be the lectotype of P. mediamericanum Pilsbry and it is even unlikely that it belonged to the type series of P. mediamericanum. It must have been mixed up with the true lectotype. The latter is missing. The two paralectotypes of P. mediamericanum Pilsbry from Chama (ANSP 45727) and three of the four paralectotypes from Orizaba (ANSP 28270) belong to the species figured as P. mediamericanum by Pilsbry (1920, Plate 4 Figures 16, 17) and identified with P. mediamericanum by Baker (1928Baker ( , 1930. However, one of the paralectotypes from Orizaba (ANSP 28270) belongs to P. comicolense. Thus, the designation of a neotype is necessary to stabilize the use of the name P. mediamericanum Pilsbry. I designate one paralectotype from Orizaba (ANSP 28270b) as neotype. The qualifying conditions specified in Art. 75.3 of the International Code of Zoological Nomenclature (International Commission on Zoological Nomenclature 2000) are fulfilled: the designation of a neotype is necessary to clarify the taxonomic status of the name P. mediamericanum Pilsbry, 1920 (Art. 75.3.1); the characters differentiating P. mediamericanum from related taxa are specified above (Art. 75.3.2); the neotype is figured ( Figure 11) and measured (D51.3 mm, D2W50.75 mm, H51.7 mm, da50.6 mm, dh50.7 mm) (Art. 75.3.3); the specimen labelled as lectotype of P. mediamericanum cannot be the lectotype, the lectotype has been mixed up and lost, all existing type material in the ANSP has been examined (Art. 75.3.4); the neotype is conspecific with the species from Chama figured as P. mediamericanum by Pilsbry (1920, Plate 4 Figures 16, 17) and identified with P. mediamericanum by Baker (1928Baker ( , 1930; thus it is likely that it is also conspecific with the lectotype designated by Baker (1963) (Art. 75.3.5); the neotype is a paralectotype from the original type locality (Art. 75.3.6); the neotype is property of the Academy of Natural Sciences, Philadelphia (Art. 75.3.7).
According to Pilsbry (1920, p 43), P. michoacanense from Morelia in Michoacán, Mexico, differs from P. mediamericanum in the lack of pitting of the surface, the lack of distinct riblets and the fewer whorls. Unfortunately, the holotype of P. michoacanense is lost. Distinct riblets, especially on the upper whorls, are present in some populations (e.g. in the type series of P. mediamericanum from Orizaba). However, most populations of P. mediamericanum are sculptured only by irregular growth lines. Probably, P. michoacanense has been based on a specimen of P. mediamericanum without distinct riblets. The measurements given by Pilsbry (1920) fall within the variability of P. mediamericanum.
The anatomy of P. mediamericanum has been described by Baker (1928).
Distribution ( Figure 15) The range of P. mediamericanum extends from Mexico to Colombia. It occurs also on Jamaica. It is most frequent at medium altitudes. Its altitudinal range extends from 75 to 2900 m altitude.

Concluding remarks
A principal component analysis of the shell measurements of the 160 Pupisoma specimens summarized in Tables I and II has been made to visualize the morphometric similarities between the examined species ( Figure 16). The two first components account for 90.7% of the variance. The first component is highly correlated with the size measurements (shell diameter, diameter of the first two whorls, diameter of the aperture, shell height, height of the aperture), whereas the second component is highly correlated with the number of whorls. The analysis shows that the species as delimited in this revision can be readily distinguished based on these measurements. The only problem is the delimitation of P. macneilli and P. mediamericanum. These two species differ in the width of the umbilicus which is not considered in the taken measurements.