Tag Archives: plekocheilus

Why photo identifications remain tricky

With the increasing ease for using social media, a larger group of people become interested in putting a name to a shell. Some call this ‘citizen science’ as they think it is a means to involve the interested general public with e.g. taxonomic work. Others see it as a harmless pastime that nobody bothers. I think neither of the two is correct.

Internet can be a great help and for taxonomy it definitely is a great resource. Think alone of the Biodiversity Heritage Library (BHL), where a multitude of sources are becoming available and are made accessible for everyone. The means are there but does this mean that everybody can pick up a shell and compare it to literature found on the internet without good knowledge of the group concerned and the relevant area? I have strong doubts.

There are a lot of pictures of snails and shells on the internet with a proper locality. However, a specific locality alone does not qualify for a proper identification. Often characteristics of the species are concealed in the picture and different views are needed to know which species (singular or plural) might be concerned. Many times photos are good enough for making a correct guess of the genus concerned, but inadequate for a correct identification at the species level. Either because the photographer didn’t take the view(s) needed for a good comparison with figures in the literature, or the specimen wasn’t full-grown which prevents from showing the required characteristics needed for a correct identification.

My basic stand is field photographs are unsuitable for identifications, unless 1) full details are available on the locality and habitat, 2) proper care has been taken to photograph the shell (or snail) from such sides that all characteristics for identification are visible. Two caveat are immediately clear here: if the animal is still present it may obscure some of the characteristics needed for identification, and it may need a basic knowledge of the family concerned to know which views are needed to enable a specialist to put a name to a shell.
Thus the baseline is: photo identifications remain tricky, and personally I’m especially wary when it comes to lesser known species or species from lesser known areas.

This having said, today an example from Venezuela. It is taken from the blogpost of Ignacio Agudo-Patron who, if I’m correctly following the links, did not have the shell at hand himself but has put a name to pictures taken by one of his ‘Facebook friends’.

schermafbeelding-2017-02-06-om-08-54-57

On first view this looks reassuring: a rather specific locality (“San Juan”, Dept. Sucre, Venezuela) and specific habitat information (premontane humid forest). There is even a reference to literature (my 2009 paper on the snail fauna of Venezuelan Guayana). Under the pictures in the blogpost is the identification “Plekocheilus (Eudolichotis) sp.”, which seems proper to me. However, the summary page of his post gives as identification “Plekocheilus (Eudolichotis) aff. gibber (Oberwimmer, 1931)”. While these pictures were taken in northern Venezuela at relatively low altitude, Oberwimmer’s taxon lives in southern Venezuela at more than 2000 m. It seems totally implausible to me that these pictures represent this species. Instead I think it is one of the coastal area species (P. (E.) distortus, and its allies) which are currently insufficiently known in their variation, distribution and relationships to allow a quick-and-dirty identification via photographs. After all, despite some scant literature, Venezuela is still one of the lesser-known areas in the Neotropics when it comes to snails.

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Sparnotion revisited

Some time ago I made a post about the subgenus Plekocheilus (Sparnotion) Pilsbry, 1944, with the type species P. (S.) hauxwelli (Crosse, 1872) as sole representative. At that time only one specimen was known from this taxon.

Thanks to Graham Oliver I was able to see another specimen, which he encountered in the Linter collection. Although the locality simply states “Peru”, there is no doubt about its identification. Compared to the paratype in the Museum of Comparative Zoology, Cambridge (Mass.), this specimen has all characteristics that were present in the lost holotype.

hauxwelli apert hauxwelli dors hauxwelli surface

Although there seems a strange twist with this species, sharing most characteristics with Plekocheilus (Eudolichotis) and one—finely zigzag hydrophanous lines on the surface—with Plekocheilus (Aeropictus), I still feel this insufficient for recognizing a separate, monotypic subgenus for this species. So I stick to my conclusion “based on the shell morphology alone we conclude that this species may be best classified as P. (Eudolichotis) hauxwelli untill more material, hopefully allowing for anatomical and molecular studies, becomes available”.

I am very grateful to Graham Oliver for sending me the information and snapshots of this shell.

Molluscs in the news

Two news items came to my attention today. The first has been taken from the Conch-L list and is about conservation of Florida land snails. “Florida Fish and Wildlife [Conservation Commission] has just sent out a posting regarding endangered and threatened species. There are two proposed rulings on Tree snails. The one  is Liguus and the other is Orthalicus. Here is the Liguus and other species  link. http://myfwc.com/wildlifehabitats/imperiled/species-action-plans/”. Only Liguus fasciatus is mentioned, together with more than 50 species of other phyla.

Liguus Florida

The ‘Science in the news’ site had an item on natural history museums and how these institutions, behind the scenes, are centers of cutting-edge research. One example is the recent discovery of a Plekocheilus species, collected back in the 1800s. More brushing off the dust than cutting the edge, but anyway…

Brushing off the dust

This morning the ZooKeys editorial office made and sent out the following press release

PR ZK

In a few days time, the paper will be published…

PS: For those wondering if I’m now turned into a true believer of using press releases for every new paper…no! But I have to admit that the Madrid museum PR office seems to be very effective 🙂

Descubren una nueva especie de molusco en la colección de malacología del MNCN.
 
Agencia SINC
 
NCYT
 
 
 
Discapnet
 
 
Bajo palabra (Acapulco)
 
 
 
 

The sound of a snail

Some time ago I posted a note on a mysterious snail found in southern Brazil, supposedly Plekocheilus aff. rhodocheilus (Reeve, 1849) (here). ‘The snail has gotten a tail’, so to speak, as the original audio fragment has been analysed and another case of sound production in land snails turned up, shedding light on this seemingly forgotten topic.

Breure2014f2

Many thanks are due to Germano Woehl jr. for sharing the original audio file.

Link: http://mollus.oxfordjournals.org/cgi/reprint/eyu079? ijkey=bXqfr0IbP5ro78U&keytype=ref 

It would be interesting to further investigate e.g. the relationships between size of the species and sound to be made.

The status of Sparnotion Pilsbry, 1944

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.

References

Bartlett, E. (1882). On some mammals and birds collected by Mr. J. Hauxwell in Eastern Peru. — Proceedings of the Zoological Society of London 1882: 373–375.
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.
Breure, A.S.H. (1978). Notes on and descriptions of Bulimulidae (Mollusca, Gastropoda). — Zoologische Verhandelingen 164: 1–255.
Breure, A.S.H. (1979). Systematics, phylogeny and zoogeography of Bulimuinae (Mollusca). — Zoologische Verhandelingen 168: 1–215. Crosse, H.C. (1872). Diagnoses molluscorum novorum. — Journal de conchyliologie 20: 211–214.
Crosse, H.C. (1873). Description d’espèces nouvelles. — Journal de conchyliologie 20: 248–254.
Pilsbry, H.A. (1895–1896). American bulimi and bulimuli. Strophocheilus, Plekocheilus, Auris, Bulimulus.Manual of Conchology (2) 10: 1–213.
Pilsbry, H.A. (1944). Peruvian land Mollusca, III. — The Nautilus 58: 28–30.
Schileyko, A.A. (1999). Treatise on Recent terrestrial pulmonate molluscs, 3. Partulidae, Aillyidae, Bulimulidae, Orthalicidae, Megaspiridae, Urocoptidae. — Ruthenica, Supplement 2: 263–436.
Simone, L.R.L. (2006). Land and freshwater molluscs of Brazil: 1–390. EGB/Fapesp, Sao Paulo.
Turner, R. D. (1962). James H. Orton – his contribution to the field of fossil and Recent mollusks. — Revista del Museo Argentino de Ciencias Naturales “Bernardino Rivadvia” (Ciencias Zoológicas) 8(7): 86–99.
Zilch,  A. (1959–1960). Gastropoda, Euthyneura. In W.  Wenz, Gastropoda. Handbuch Paläozoologie 6, 2: 1–835. Borntraeger, Berlin.

Photo of the day (149): Plekocheilus

Philippe Kok very kindly shared some additional photographs of living Plekocheilus snails from tepuis in Venezuelan Guayana.

The first picture was taken at night on Auyán-tepui in the Chimantá massif. It is a very yellow coloured specimen of P. (Eurytus) mundiperditi Haas, 1955. This species is well known from this area and may be found on several of the tepuis in this massif.

The second snail was found on Uei-tepui, also known as Cerro El Sol, an isolated mountain-top south-east of Roraima. This tepui was hitherto malacologically terra incognita, but the photo is interesting in several aspects. First, this appears to be P. (E.) sophiae Breure, 2009, which was until now only known from Yuruani-tepui, NW of Roraima. Secondly, this shell has had a severe ‘life accident’ as shown by the upper part of the last whorl near the peristome; looks like a repaired shell after a predator attack (mammal??). Finally, the colour pattern at the penultimate whorl is peculiar (lighter and darker spiral bands), but has been observed in other species as well; this may be due to either a genetic defect regulating the colour pattern genes or may have been induced by another damage of the shell (on the side not shown here).

More information on this group may be found via this link: http://bit.ly/IOYgok

Plekocheilus mundiperditi Plekocheilus sophiae