Photo of the day (181): Rabdotus

Bill Frank and Harry Lee added to their site a record and photo of a live Rabdotus dealbatus (Say, 1821), the so-called Whitewashed Rabdotus.

218rab
This snail was found on grass stalks at the base of a limestone cutting, during light rain, between mile 58 and 59 markers along Interstate 840, Rutherford Co., Tennessee on 7 October 2019 (shell height 14 mm).

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Left-right chirality

Dextral and sinistral coiling shells are well known throughout the molluscan phylum, but the genetic mechanism was unresolved so far. Abe & Kuroda have recently published  a paper which answers the question.

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Their abstract reads “The establishment of left-right body asymmetry is a key biological process that is tightly regulated genetically. In the first application of CRISP/Cas9 to a mollusc, we show decisively that the actin-related diaphanous gene Lsdia 1 is the single maternal gene that determines the shell coiling direction of the freshwater snail Lymnaea stagnalis. Biallelic frameshift mutations of the gene produced sinistrally coiled offspring generation after generation, in the otherwise totally dextral genetic background. This is the gene sought for over a century. We also show that the gene sets the chirality at the one-cell stage, the earliest observed symmetry-breaking event linked directly to body handiness in the animal kingdom. The early intracellular chirality is superseded by the intercellular chirality during the 3rd cleavage, leading to asymmetric nodal and Pitx expression, and then to organismal body handedness. Thus, our findings have important implications for chromophogenesis in invertebrates as well as vertebrates, including humans, and for the evolution of snail chirality”.

This is a breakthrough that has importance beyond malacology. While it sheds light on the occurrence of sinistrality in certain groups (e.g. Clausiliidae), it doesn’t completely answer the question why it occasionally (or with different frequency) is found found in other groups of snails. Is it just a mutation or is there more at play?
Anyway, since sinistrality is also found in some Neotropical groups, this is an interesting paper.

Reference:
Abe, M. & Kuroda, R., 2019. The development of CRISP for a mollusc establishes the formin Lsida1 as the long-sought gene for snail dextral/sinistral coiling. – Development, 146: dev175976 (7 pp.).

J.L. Staid-Staadt revisited

Just published: a paper dealing with the French malacologist and palaeontologist Jean Louis Léon Staadt (1886-1969), also known as John L. Staid or J.L. Staid-Staadt (hereafter JLS). The first time I came across his name was when preparing a manuscript about the Bravo collection (Mogollón & Breure, 2008). He was the main European correspondent of Bravo. But little was known about this person, except a short paper by a fellow-Dutchman who had visited him shortly before his death.

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During one of my visits to the Paris museum the large collection of JLS was noticed, incorporated in the general collection. Virginie Héros kindly made me aware of documentation, which appeared to be detailed notes by JLS handwritten in ‘year books’. Unfortunately they are not complete; some years are missing and they end in 1940. The details intrigued me as they gave insight not only in the contact network of JLS, the financial aspects of building a collection in the period 1920-1940, but also about the person of JLS. What initially still remained enigmatic was the time he had spent in England, where he adopted the name John L. Staid. During a visit in London I was able to trace his former house, some of his activities and also recovered that he was married twice there.

Besides the biographical details, the paper gives a bibliography, list of new taxa, a list of eponyms, and in the Appendices a verbatim transcription of the summaries from JLS’ year books, and a list of contacts and correspondents.

References:
Breure, A.S.H., 2019. Obsessed with shells: John L. Staid-Staadt (1886-1969) as a life-long and ardent collector. – Folia Conchyliologica 50: 5-74. Link
Mogollón, V. & Breure, A.S.H., 2008. José Julián Bravo (1874-1927), a hitherto unknown conchologist from Peru. – Basteria, 83: 601-613.

Revision of Hyperaulax

Freshly pressed: a paper by Salvador & Cavallari on the Brazilian genus Hyperaulax. “The genus Hyperaulax Pilsbry, 1897 comprises two living species endemic to the oceanic Fernando de Noronha Archipelago, offnorth-eastern Brazil. They are currently allocated in two subgenera, Hyperaulax s. str. and Bonnanius Jousseaume, 1900, belonging to the family Odontostomidae. Herein we present a taxonomic revision of these species, assessing their familiar allocation within Orthalicoidea, offering updated diagnoses and descriptions, figuring the type materials and further relevant specimens, and providing barcoding DNA sequences. We conclude that Bonnanius is a junior synonym of Hyperaulax, which is classified in Odontostomidae.The genus contains two valid species, H. ridleyi and H. ramagei, both endemic to Fernando de Noronha“.

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This genus has been associated also with Floridian fossils for many years, until Auffenbach et al. showed that these fossils belonged to the Bulimulidae. This revision of the two species neatly shows that subgeneric splitting should be avoided.

Reference:
Salvador, B.R. & Cavallari, D.C., 2019. Taxonomic revision of the genus Hyperaulax Pilsbry, 1897 (Gastropoda, Stylommatophora, Odontostomidae). Zoosystema and Evolution, 95 (2): 453–463.

 

Ovachlamys in Brazil

Just published: a report that confirms the occurrence of a new invasive snail in this country. “The occurrence of the invasive non-native Asiatic jumping land snail Helicarionidae Ovachlamys fulgens (Gude, 1900) is finally confirmed by us in the southern Brazil region, specifically on the Santa Catarina State territory, from previous records available since the year 2013 “masked” under the identity of another species. This report increases to 27 the number of exotic continental molluscs confirmed in the State of Santa Catarina/ SC.“.

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Not surprisingly the occurrences are mainly situated near the region where the port activities occur. I wouldn’t be surprised if these snail travel with sea containers, as the distribution of Bulimulus sp. suggests (ongoing research, unpublished data).

Reference:
Aguda-Padron, I., 2019. Confirmed occurrence of the invasive asiatic jumping land microsnail Helicarionidae Ovachlamys fulgens (Gude, 1900) in the Southern Brazil region. – Bioma (El Salvador) 5 (49): 11–15.

Veronicellids recharacterised

Just published: a paper by Rocha & D’ávila on the Veronicellid genera Latipes and Angustipes.

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Their abstract is “The genera Angustipes Colosi, 1922 and Latipes Colosi, 1922 were originally proposed as “groups” within the genus Vaginulus Ferrussac, 1822, and since their establishment they have been variously considered valid or invalid until they gained the ultimate status of genus. The descriptions of both genera are general and broadly inclusive, and this fact has complicated taxonomic recognition. Additionally, incomplete descriptions and difficult identification of characteristics in the name-bearing type specimens demonstrate the need to revisit the species and revise the two genera. Herein, we broaden the description of Latipes erinaceus Colosi, 1922 with respect to the circulatory system, the radula, the jaw, the position of entry of the ligation duct in the bursa copulatrix in relation to the canal of the bursa, the origin of the muscle of the penial gland, along with the morphometric characteristics of the phallus, the penial gland, the pedal gland, and the bursa copulatrix. We also propose new differential diagnoses for the genera Angustipes and Latipes, limited to the essential characteristics that enable taxonomic recognition. Hence, we propose the assignment of the species L. erinaceus, Latipes rosilus (Thiele, 1927), Latipes ribeirensis (Thiele, 1927), and Latipes absumptus (Colosi, 1921) to the genus Angustipes, based on the presence of morpho- logical characteristics attributable to this genus, such as the phallus being short and conical; the bursa copulatrix being sessile or short, and lacking a head; the ligation duct inserted near the canal of the bursa; as well as on the similarity in phallus morphology with Angustipes difficilis Colosi, 1922, the type species of this genus“.

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The family Veronicellidae is notoriously enigmatic due to the need to use anatomical charcters for classification. This paper is thus a welcome addition to the literature of this family.
Reference:
Rocha, C.A. & D’ávila, S., 2019. New Morphological Characterization of Latipes erinaceus (Gastropoda, Veronicellidae), Differential Diagnosis for the Genera Angustipes and Latipes, and Novel Combinations for Species of Latipes. – Zoological Science (Tokyo), 36 (3):231-241.

A misidentified prey

In 2002 R. Williams published a brief note on a bird, the Scaled Fruiteater Ampeliodes tschudii, which had been observed near Tandayapa in Ecuador with a snail in its beak.

 

According to information given to him by a third person, only two species of terrestrial snail were living in that area: “the arboreal Plekocheilus sp. and a large terrestrial form in the family Pleurodontidae [now Labyrinthidae]”. Mr. Williams concluded that it must have been the Plekocheilus species that was caught by the bird.

Apart from the obvious errors in the sentence quoted above (both snails are terrestrial, and Plekocheilus species are not truly arboreal), it is clear from the picture provided in the note and copied above that the prey was misidentified. The shell in the bird’s beak look definitely like a Drymaeus species and the most likely candidate is Drymaeus aequatorianus (E.A. Smith, 1877) which is known from that region.

Reference:
Williams, R.S.R., 2002. Consumption of arboreal snails by Scaled Fruiteater Ampeliodes tschudii. – Cotinga, 18: 100.