Tag Archives: drymaeus

Photo of the day (173): Drymaeus

The group ‘Speurneuzen’ makes nearly every week a hike on the Island of Curaçao, usually to look for cultural-historical objects, but always to enjoy nature. This week they followed a new trail made by ‘Uniek Curaçao’ from Fort Kloof to Ascuncion. From their photo report I show a small batch of Drymaeus elongatus on a Wayaca tree.

The picture was made by Fred Chumaceiro.

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Drymaeus tripictus ecology

Zaidett Barrientos have made an important contribution to the ecology of Neotropical snails to study the ecology and biology of Drymaeus tripictus (Albers, 1857) in Costa Rica. The abstract of the recent paper is as follows: “Very little is known about the ecology and biology of Drymaeus tripictus, an extremely rare and endemic land snail species from Costa Rican highlands. I studied the ecology and reproductive biology of D. tripictus from April 2009 through June 2010 in an old forest, a young forest and a Cupressus lusitanica plantation in central Costa Rica. Every three months I visited each habitat and collected specimens in 20 random sampling plots (3×3 m2 each). I observed the snail’s activity and microhabitat preference in the field, and in the labora- tory I recorded high definition videos of its mating behavior and analyzed reproductive morphology with light microscopy. The snail is more abundant in the old forest (0.017 ind./m2) and prefers leaves with little epiphyllous cover (0-25 % cover, chi-square test, p <0.0001). During the dry season the snails become active between 20:00 pm and 8:00 am (chi-square = 22.65, df=3, p < 0.0001); they are inactive mainly during the afternoon (11:00 am to 16:59 pm). I found active individuals mostly on the upper side of leaves, where they feed (Chi-square =6.76, df=1, p = 0.0093). Mating is unilateral, by shell mounting, with cryptic phallus intromission and without role switching or multiple mating. Its reproductive system is morphologically similar to that of Drymaeus costaricensis. Mating behavior is as expected for snails with high-spired shells, except for the lack of role switching. The density of D. tripictus is low even when compared with other endangered bulimulids”.

schermafbeelding-2016-11-30-om-15-42-37

A very interesting paper, which I had the pleasure to review as a draft (although not acknowledged).

Reference:
Barrientos, Z., 2016. Reproductive system, mating behavior and basic ecology of an extremely rare tropical snail: Drymaeus tripictus (Stylommatophora: Bulimulidae). – Revista de Biología Tropical, 64(1): 55–68.

Bulimulids introduced in the Pacific

Carl Christensen kindly sent me two papers which testify that two members of the Bulimulidae have been introduced to Pacific Islands.

The first one is an inventory of introductions in the Hawaiian Islands (Hayes et al., 2012). Bulimulus guadalupensis is reported from one of the islands.

schermafbeelding-2016-10-28-om-08-31-24

“This species originated in the Caribbean, where it is widespread, especially in disturbed habitats. It has been introduced to Florida, probably in association with agricultural or horticultural plants, and has been recorded in abundance in lawns and among ornamental plants in a residential area, as was the present material. It is likely that it was introduced via the horticultural trade. The only two localities at which the species has been found in the Hawaiian islands were close together and were also the only two localities at which Vallonia pulchella was found”.

In the second paper the occurrence of Drymaeus multilineatus (Say, 1825) is recorded on the island of Guam. According to Christensen, this species was introduced on that island before 1978, “likely inadvertently with cultivated plants” (Kerr & Bauman, 2013).

References:
Hayes, K.H., Yeung, N.W., Kim, J.R. & Cowie, R.H., 2012. New records of alien Gastropoda in the Hawaiian Islands: 1996-2010. – Bishop Museum Occasional Papers, 112: 21-28.
Kerr, A.M. & Bauman, S., 2013. Annotated checklist of the land snails of Mariana Islands, Micronesia. – University of Guam Marine Laboratory Technical Report, 148: i-vii, 1-72.

Ecology of Costa Rican Drymaeus

Recently a very interesting paper has been published by Zaidett Barrientos (2016), describing the genitalia, mating behaviour and providing ecological data of the Costa Rican species Drymaeus tripictus (Albers, 1857).

The abstract reads “Very little is known about the ecology and biology of Drymaeus tripictus, an extremely rare and endemic land snail species from Costa Rican highlands. I studied the ecology and reproductive biology of D. tripictus from April 2009 through June 2010 in an old forest, a young forest and a Cupressus lusitanica plantation in central Costa Rica. Every three months I visited each habitat and collected specimens in 20 random sampling plots (3×3 m2 each). I observed the snail’s activity and microhabitat preference in the field, and in the laboratory I recorded high definition videos of its mating behavior and analyzed reproductive morphology with light microscopy. The snail is more abundant in the old forest (0.017 ind./m2) and prefers leaves with little epiphyllous cover (0-25 % cover, chi-square test, p <0.0001). During the dry season the snails become active between 20:00 pm and 8:00 am (chi-square = 22.65, df=3, p < 0.0001); they are inactive mainly during the afternoon (11:00 am to 16:59 pm). I found active individuals mostly on the upper side of leaves, where they feed (Chi-square =6.76, df=1, p = 0.0093). Mating is unilateral, by shell mounting, with cryptic phallus intromission and without role switching or multiple mating. Its reproductive system is morphologically similar to that of Drymaeus costari- censis. Mating behavior is as expected for snails with high-spired shells, except for the lack of role switching. The density of D. tripictus is low even when compared with other endangered bulimulids”.

Schermafbeelding 2016-06-22 om 12.27.02

Supplementary files on the journal’s website are supposed to be videos of the mating, but these were unavailable at the time of writing.

Reference:
Barrientos, Z., 2016. Reproductive system, mating behavior and basic ecology of an extremely rare tropical snail: Drymaeus tripictus (Stylommatophora: Bulimulidae). – Revista  de Biologia Tropical 64 (1): 55–68.

Field observations on Curacao

Just appeared: a paper by Gerard van Buurt with field observations and new records on the malacofauna of Curacao. Especially the ecological observations are very interesting and a new hypothesis is formulated which may explain the disjunct distribution of Drymaeus elongatus on the island.

Buurt2016_1

The abstract reads: “Currently 31 species of terrestrial snails are known from Curaçao, 28 of these are indigenous. The taxonomy of Curaçao land snails has been studied quite well. An inventory of species and subspecies exists. About their ecology however much less is known. The influence of salt spray from the sea on the distribution of some species is discussed. By observing snails in the field some conclusions about their ecology have been reached; these and some further assumptions are hereby presented. Three of the larger species of indigenous snails are discussed. These are Cerion uva, Drymaeus elongatus and Tudora megacheilos. The introduced snails Bulimulus guadalupensis, Zachrysia provisoria and Achatina fulica (= Lissachatina fulica) are briefly mentioned; the latter two are new records for Curaçao”.

Buurt2016_2

Reference:
Buurt, G. van, 2016. Field observations on some Curacao landsnails, and new records for its fauna. – Folia Conchyliologica 34: 1–16. Link to PDF

 

Photo of the day (164): Drymaeus and Cerion

The ‘Speurneuzen’ on the island of Curacao, on their weekly trips, have supplied some living snail pictures again. This trip was to the former estate of Zorgvliet in Christoffel nature park, and due to some rain during the start of their trip, snails awoke from their hibernating stage.

Intel(R) IPP JPEG encoder [7.1.37466] - Sep 25 2012;

This is Drymaeus elongatus.

12 Een gezellige boel - foto Carel13 Junior gaat er van door - fto Carel

These pictures are of Cerion uva.

Many thanks again to Fred Mendez Chumaceiro and Carel de Haseth for photographing them, and to Francois van der Hoeven for sharing them.

Photo of the day (163): Drymaeus and Cerion

François van der Hoeven regularly sends reports of small expeditions to discover forgotten and new things on the island of Curaçao. This time a report on their wanderings at plantation Wacao. At the end of their trip the rain started pouring. Time for snails to become awake and be on the move…

29 Nu gaan de slakken lopen - foto Carel 30 Zelfs de Cerion uva - foto Carel

These two pictures of Drymaeus elongatus respectively Cerion uva were made by Carel de Haseth.