Phylogenetic data on Sagdoidea

As an advance online publication, recently appeared the paper by Sei et al. on the phylogenetic relationships within the Sagdoidea.

The abstract reads: “We performed multi-locus, time-calibrated phylogenetic analyses of Jamaican Pleurodontidae to infer their relationships within pulmonate land snails. These analyses revealed that Sagdoidea, with about 200 species in the Caribbean Basin and neighbouring regions, is the sister group of Helicoidea with about 4700 species worldwide and that these superfamilies diverged 61–96 Ma. Morphological disparity in Sagdoidea is similar to that in Helicoidea despite its much lower species richness. Helicoidea originated in the New World and colonized the Old World 46–64 Ma. Pleurodontids and sagdids colonized Jamaica 15.0–18.4 and 12.8–16.5 Ma, respectively, consistent with geological estimates of Jamaican subaerial emergence by mid-Miocene. Allopatric convergence in shell morphologies required caution in using fossils from outside the geographic range of ingroup taxa to calibrate molecular clock estimates. Estimates of ages of clades varied by 24–55%, depending on the calibration points included. We use these results to revise Helicoidea and Sagdoidea. Pleurodontids from Jamaica and the Lesser Antilles were reciprocally monophyletic but other putative pleurodontids grouped basally in Helicoidea as Labyrinthidae (new family), or with Sagdidae. Newly recognized members of Sagdoidea are Solaropsinae and Caracolinae (Solaropsidae), Polydontinae (Sagdidae) and Zachrysiidae (new family). Pleurodontidae is restricted to two subfamilies, Pleurodontinae, in the Lesser Antilles, with Gonostomopsinae, a synonym, and Lucerninae resurrected for the Jamaican endemic genera Lucerna, Dentellaria, Thelidomus and Eurycratera. Lucerna and Dentellaria have been treated as subgenera of Pleurodonte, but rendered it paraphyletic in our analyses”.

This is a nice piece of research for which the authors did extensive DNA research with 3 loci and divergence time analysis. This resulted in a major taxonomical revision of the group, defining the Pleurodontidae and erecting the Labyrinthidae and Zachrysiidae.

Sei, M., Robinson, R.G., Geneva, A.J. & Rosenberg, G., 2017. Doubled helix: Sagdoidea is the overlooked sister group of Helicoidea (Mollusca: Gastropoda: Pulmonata). – Biological Journal of the Linnean Society, XX: 1-32 [advance online publication, hence the correct reference will be different].


Achatina fulica: effectiveness of removal methods

The Giant African Snail, Achatina fulica (or Lissachatina f.) is difficult to eradicate once established. This species was introduced in several South American countries and several researchers have made studies on its distribution and possible eradication. One of such studies is by Garcés-Restrepo et al. (2016).

The presence of the giant African snail Achatina fulica (Bowdich 1822) was confirmed in Colombia in 2008. Due to economic and health implications of this species and the difficulties in controlling it, it is essential to establish the relevance of protocols and alternative inexpensive substances used to control the snail. In this research, the effectiveness of manual removal and manual removal with spray of calcium oxide was analyzed. Both techniques had similar efficiencies, so it is recommended that calcium oxide should be implemented only for the disposal of the collected individuals in order to reduce costs and decrease the impact on arthropofauna. In addition, we evaluated the molluscicide ability of commercial sodium hypochlorite, two plant extracts (Tabebuia rosea and Jatropha curcas), and commercial molluscicide (metaldehyde). We found that the three alternative substances were effective as molluscicides, but with lower effectiveness than the commercial substance. Implementation of the extracts of T. rosea and J. curcas is recommended because they have low cost, and do not present negative effects on the environment”.

Garcés-Restrepo, M. et al., 2016. Sustancias alternativas para el control del caracol africano (Achatina fulica) en el Valle del Cauca, Colombia. – Biota Colombiana, 17: 44-52.

Morphometrics using photographs

In many cases morphometric studies are done taking landmarks using photographs. There appears to be of distortion, which has been studied in the recent paper by Collins & Gazley (2017).

Most geometric morphometric studies are underpinned by sets of photographs of specimens. The camera lens distorts the images it takes, and the extent of the distortion will depend on factors such as the make and model of the lens and camera and user-controlled variation such as the zoom of the lens. Any study that uses populations of geometric data digitized from photographs will have shape variation introduced into the data set simply by the photographic process. We illustrate the nature and magnitude of this error using a 30-specimen data set of Recent New Zealand Mactridae (Mollusca: Bivalvia), using only a single camera and camera lens with four different photographic setups. We then illustrate the use of retrodeformation in Adobe Photoshop and test the magnitude of the variation in the data set using multivariate Procrustes analysis of variance. The effect of photographic method on the variance in the data set is significant, systematic, and predictable and, if not accounted for, could lead to misleading results, suggest clustering of specimens in ordinations that has no biological basis, or induce artificial oversplitting of taxa. Recommendations to minimize and quantify distortion include: (1) that studies avoid mixing data sets from different cameras, lenses, or photographic setups; (2) that studies avoid placing specimens or scale bars near the edges of the photographs; (3) that the same camera settings are maintained (as much as practical) for every image in a data set; (4) that care is taken when using full-frame cameras; and (5) that a reference grid is used to correct for or quantify distortion”.

There is more that can be wrong than one can suspect, so this might be a useful study for those who are applying morphometrics in their taxonomical work.

Collins, K.S. & Gazley, M.F., 2017. Does my posterior look big in this? The effect of photographic distortion on morphometric analyses. – Paleobiology, 43: 508-520.

Galapagos micromolluscs

An interesting paper was recently published by Miquel & Bungartz on micromolluscs found among Galapagos lichens and bryophytes, including a new species.

The new species is a carnivorous snail, Scolodonta rinae, and this family is reported for the firt time from the Galapagos. Other species that were encountered are Pupisoma galapagorum, P. dioscoricola, Tornatellides chathamensis, Helicina sp., and Succinea sp.

The new species was found on the island of Santa Cruz.

Miquel, S.E. & Bungartz, F., 2017. Snails found among herbarium specimens of Galapagos lichens and bryophytes, with the description of Scolodonta rinae (Gastropoda: Scolodontidae), a new species of carnivorous micro-mollusk. – Archiv für Molluskenkunde, 146 (1): 173-186.

Euthanasia techniques for snails

Collecting snails in the field or bringing them into the laboratory often results in killing and preserving the animals. Gilbertson & Wyatt (2016) have evaluated several techniques for doing so.

The euthanasia of invertebrates used in scientific investigations poses unanswered questions regarding the rapid induction of unconsciousness with minimal distress and pain. Relative to vertebrates, invertebrates’ sensory experience of pain, nociception, and physiologic response to aversive stimuli are poorly characterized. The scientific communities in the European Union, Canada, United States, Australia, and New Zealand join in consensus regarding the need to address alleviation of pain and distress in cephalopods (octopus, squid, and so forth), which have the best-characterized nervous system among invertebrates. In the current study, we evaluated various euthanasia techniques in a terrestrial gastropod species, with priority on animal wellbeing, scientific variability, feasibility in both field and laboratory settings, and acceptability by personnel. In addition, we demonstrated that the 2-step method of euthanasia described in the AVMA Guidelines as acceptable for aquatic invertebrates is effective for terrestrial snails and meets all welfare and scientific requirements. This 2-step method first induces anesthesia by immersion in 5% ethanol (laboratory-grade ethanol or beer) followed by immersion in a euthanizing and tissue-preserving solution of 70% to 95% ethanol or 10% neutral buffered formalin. Furthermore, alternative methods of euthanasia for terrestrial snails commonly used in field research, such as live immersion in concentrated ethanol or formalin, were shown to be unacceptable”.

For sure, the acceptance of beer will be welcomed by many field workers…

Gilbertson, C.R. & Wyatt, J.D., 2016. Evaluation of euthanasia techniques for an invertebrate species, land snails (Succinea putris). – Journal of the American Association for Laboratory Animal Science, 55: 577-581.

A brief Barbados visit

Today I saw the paper published by Franke already in 2015. Because of its interests for this blog, it is summarised here.

During a short visit to Barbados, the author found specimens of Pseudopineria barbadensis Kraus, 1996 and describes its habitat. From the same site a second species is reported, Truncatella barbadensis Pfeiffer, 1856.

Franke, S., 2015. Fundortbestätigung: Pseudopineria barbadensis Kraus 1996 (Pulmonata: Urocoptidae) auf der Insel Barbados. – Mittheilungen Club Conchylia, 25: 19-22.

World Scientists’ Warning to Humanity

Today another tidbit, relevant for those of you who are scientists working for or affiliated to an institution. Please read the following an consider co-signing the paper in preparation by following the link below.


Dear Scientist,

Twenty five years ago, in 1992, the Union of Concerned Scientists and more than 1500 scientists published the famous declaration entitled “World Scientists’ Warning to Humanity”. They called on humanity to curb environmental destruction, warning “all humanity that a great change in our stewardship of the earth and the life on it is required, if vast human misery is to be avoided.” Now, on the 25th anniversary of their famous call, we looked back at their warning and evaluated the human response over the last quarter century. This 25-year update will soon be published by BioScience.

To see the in press article “World scientists’ warning to humanity: a second notice” and add your name as a signatory, click:

This short article is only 1,000 words long and can be read in 6 minutes. If you are a scientist, we invite you to endorse this article by adding your name to the co-signatory list. In doing so, when the article is published by BioScience, you will be included in the full list of signatories in the article’s online supplemental material. We invite all types of scientists to sign (e.g. ecologists, economists, social scientists, medicine, etc.) including graduate students in the sciences.

Please forward this email to any other scientists in your contact list that may also be interested in signing. For example, you could simply forward this email to your working group or Listserv.  If you use Twitter, consider inviting your colleagues to add their signatures by including #ScientistsWarningToHumanity in a tweet.

With your help, by forwarding this email to your scientist contacts, we will have many more scientists as co-signatories to present to world leaders. Thanks for helping get this important message to world leaders and to humanity. As of today, the article has been signed by more than 13,000 scientists from 180 countries.


Thank you, Bill

William J. Ripple

Distinguished Professor of Ecology

Department of Forest Ecosystems and Society

Richardson Hall #321

Oregon State University

Corvallis, OR 97331