In 1872, Hippolyte C. Crosse published a brief paper with diagnoses of new molluscs, one of which was Bulimus hauxwelli (Crosse, 1872: 211). This species was named after John Hauxwell, who collected mainly birds, mammals and fishes during trips in Peru and Ecuador (Bartlett 1882; Böhlke 1984). Hauxwell collected this malacological material near the Ambiyacu river, at Pebas, Dept. Loreto, eastern Peru and donated it to James Orton, whose collection at that time was kept in Vassar College, Poughkeepsie, NY.
Crosse (1872: 211), who did not state on how many specimens his description was based, referred to “Col. Orton”. He further remarked “Species insignis, ad sectionem Pelecychilorum Guildingi pertinens, inter Bulimum goniostomum Ferussaci et B. distortum Bruguierei quasi media”; this may be liberally translated in ‘A remarkable species belonging to Pelecychilus Guilding, halfway between Bulimus goniostomus Férussac [Gonyostomus gioniostomus, Strophocheilidae, eastern Brazil (Simone 2006: 203)] and B. distortus Bruguière [Plekocheilus (Eudolichotis) distortus, Amphibulimidae, northern South America (Borrero & Breure 2011: 50-51, fig. 14E)]’. During the next year Crosse published a French translation and a figure of this species (Crosse 1873: 252-253, pl. 11 fig. 2). He said it was communicated via Thomas Bland, correspondent for the Journal de Conchyliologie in New York.
Pilsbry (1896 [1895-1896]: 120-121, pl. 44 figs 75-78) re-described and re-figured this taxon “through the courtesy of Prof. William B. Dwight, of Vassar College” on the basis of “the type and another specimen preserved in the museum of that college”. One of these specimens is now in the collection of the Museum of Comparative Zoology at Harvard, Cambridge, MA (MCZ 202073). Turner (1962) explained that in 1874 the type material, returned to Orton after the description by Crosse, has been transferred to the MCZ collection. Unfortunately, after Pilsbry used the holotype for his re-description, it “has since been misplaced or lost”; the MCZ specimen is thus a paratype. Pilsbry classified the species with his subgenus Plekocheilus (Eudolichotis) Pilsbry, 1896 and singled P. (E.) hauxwelli out in the key for the subgenus (Pilsbry 1896 [1895–1896]: 109), distinguishing it from P. (E.) distortus (Bruguière, 1789) and P. (E.) aurissciuri (Guppy, 1866) by having (1) a “minutely, densely but irregularly scattered, papillose” sculpture on the last whorl; (2) “longitudinal groups of crowded, finely zigzag hydrophanous lines” on the dorsal side of the last whorl (Pilsbry 1896 [1895-1896]: pl. 44 fig. 78); (3) a narrow, “not calloused” lip. Many years later, Pilsbry (1944) referred to this characteristics presented in this key to define his new subgenus Plekocheilus (Sparnotion), with its sole species P. (S.) hauxwelli. This subgenus has been recognised by Zilch (1960 [1959-1960]: 476, fig. 1674), and Breure (1979: 32); Schileyko (1999: 277: fig. 334) expressed some doubt about its status by placing a question mark, but did not explicitly comment on this in his text.
The loss of the holotype of Bulimus hauxwelli makes it necessary to judge this taxon—and the subgenus Spanotion—largely on the basis of the figures provided by Pilsbry and the remaining paratype in MCZ. As far as I know there is no material with proven locality data present in museum collections. Recently, I had the opportunity to re-study the specimen in MCZ on the basis of hi-res pictures supplied by Adam Baldinger. As noted earlier (Breure 1978: 22), the paratype does not show the “longitudinal groups of crowded, finely zigzag hydrophanous lines” very clearly and this could hardly be compared to the subcuticular cavities filled with air characteristic for Plekocheilus (Aeropictus); see also Borrero & Breure 2011: fig. 6 for shell sculptures of several Plekocheilus species. While the paratype shell shows a papillose sculpture of the last whorl (unfortunately not clearly shown on the picture), I think this sculpture is not atypical compared to the known species of Plekocheilus (Eudolichotis). The sprout in the basal lip seems stronger than in Crosse’s or Pilsbry’s figures; this may be a sign for intra-specific variation. Finally, the narrow and ‘not calloused’ lip reminds me of several Plekocheilus (Eurytus) species and I hardly doubt if this characteristic alone may be sufficient for a subgeneric separation of this species.
Based on the shell morphology alone I conclude that this species may be best classified as P. (Eudolichotis) hauxwelli untill more material, hopefully allowing for anatomical and molecular studies, becomes available.
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Böhlke, E.B. (1984). Catalog of type specimens in the ichthyological collection of the Academy of Natural Sciences of Philadelphia. — Special Publication Academy of Natural Sciences of Philadelphia 14: i–viii, 1–246.
Borrero, F.J. & Breure, A.S.H. (2011). The Amphibulimidae (Mollusca: Gastropoda: Orthalicoidea) from Colombia and adjacent areas — Zootaxa 3054: 1–59.
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