Monthly Archives: June 2015

Miocene fossils from Florida

Auffenberg et al. (2015) just released a new paper on fossils from the Miocene in Florida. The land shells fossils have hitherto been considered as Odontostomidae, which as extant species occur in the southern part of South America. Consequently, some ‘mental flexibility’ was needed to explain the biogeography of these fossils.

“Orthalicoid terrestrial snails recorded from the lower Miocene portion of the upper Oligocene to lower Miocene Tampa Member of the Arcadia Formation (Hawthorn Group) of southern Florida and the lower Miocene St. Marks Formation of northern Florida are reviewed. These taxa, previously allocated to the genus Hyperaulax Pilsbry, 1897 (Odontostomidae), are reassigned to Tocobaga new genus (Bulimulidae) on the basis of a distinctive suite of morphological characters, particularly those of the peristome and the embryonic whorl sculpture. Examination of all type material of the fossil taxa historically assigned to Hyperaulax reveals that only three species are separable (Partula americana Heilprin, 1886; Bulimulus americanus wakullae Mansfield, 1937; and Bulimus floridanus Conrad, 1846). The varietal names Bulimulus americanus var. partulinus and B. americanus var. laxus, both Dall, 1890, are indistinguishable from the nominate form in any important morphological character. Bulimulus heilprinianus, Bulimulus stearnsii, both Dall, 1890, and Bulimulus ballistae, Bulimulus remolina, Bulimulus tampae, and Bulimulus tortilla, all Dall, 1915, are synonyms of B. floridanus Conrad, 1846. The status of B. a. wakullae from northern Florida is problematic. Although clearly not conspecific with P. americana, it is tentatively assigned to Tocobaga new genus and is herein elevated to species level. The biogeography of Tocobaga new genus is tentatively discussed. Fossiliferous deposits in North America and South America have not yielded taxa with the combination of shell characters found in the new genus and relationships with other bulimulid genera are unknown. However, it is probable that the new genus, like other non-marine mollusks from the Tampa Member of the Arcadia Formation, dispersed to Florida after contact between the Caribbean Plate and the Bahama Platform (circa 38 Ma)”.

Auffenbach et al 2015

Reference:
Auffenberg, K., Slapcinsky, J. & Portell, R.W., 2015. A revision of the fossil taxa assigned to Hyperaulax (Gastropoda: Odontostomidae), with the description of a new genus (Gastropoda: Bulimulidae). – The Nautilus 129: 54–62.

Extinction of land snails

My gut feeling about the IUCN Red List, the stringent and bureaucratic procedure involved, and the few land snails listed on it, have given me an uneasy feeling for quite some years. Now Régnier et al. (2015) have published a study in which they offer an alternative approach, viz. with a mixture of a model study and expert opinions.

Their abstract is brief: “Since the 1980s, many have suggested we are in the midst of a massive extinction crisis, yet only 799 (0.04%) of the 1.9 million known recent species are recorded as extinct, questioning the reality of the crisis. This low figure is due to the fact that the status of very few invertebrates, which represent the bulk of biodiversity, have been evaluated. Here we show, based on extrapolation from a random sample of land snail species via two independent approaches, that we may already have lost 7% (130,000 extinctions) of the species on Earth. However, this loss is masked by the emphasis on terrestrial vertebrates, the target of most conservation actions. Projections of species extinction rates are controversial because invertebrates are essentially excluded from these scenarios. Invertebrates can and must be assessed if we are to obtain a more realistic picture of the sixth extinction crisis”. But their summarizing figure shows the following picture:

Schermafbeelding 2015-06-15 om 16.03.46

From their discussion I derive the following quotes: “The current Red List underestimates the actual number of extinct and threatened invertebrate species: there are almost seven times as many extinctions in our sample as would have been listed following the IUCN criteria, and we suggest that discrepancies of this order of magnitude, or greater, given that mollusks are one of the better known invertebrate groups, should be expected for other invertebrate groups. (…) a number of studies and our own work suggest that invertebrate extinctions are mostly overlooked: we suggest that we have probably already lost 7% of described living species of the world. On oceanic islands, there is evidence that this percentage is much higher”. This is really alarming!

Their method involved a random selection of taxa that have been assessed. For the Neotropical realm the following species were involved: Amphistemma pilsbryanum, Arangia aequatoris, Bostryx apertus, Bostryx baeri, Bostryx dentaxis, Bostryx gayi, Bostryx haasi, Brachypodella collaris, Bulimulus erectus, Bulimulus inermis, Callocoptis vesperalis, Capillacea angustior guamaensis, Cochlodinella variegata, Dentellaria chemnitziana, Drymaeus albolabiatus, Drymaeus chaperi, Drymaeus combinai, Drymaeus icterostomus, Drymaeus mexicanus, Drymaeus picturataEucalodium moussonianum, Eurytus ameghinoi, Eurytus glandiformis, Eurytus pirriensis, Gongylostomella fortis, Guestieria martinida, Hispaniolana gigantea, Labyrinthus stolzmanni, Leiostracus coxiranus, Leiostracus spiritualis, Liparotes obesulus, Liparotes obesulus obesus, Lyobasis binneyi, Martirelix huertai, Obeliscus pattalus, Plagioptycha duclosiana abacoensis, Plekocheilus appuni, Praticolella berlandieriana, Radiodiscus ditzleri, Stenostylus meleagris, Streptostyla chiriquiana, Streptostyla flavescens boucardi, Streptostyla irrigua, Streptostyla potosiana, Thaumastus integer, Thaumastus yanamensis, Torrecoptis polita, Trilamellaxis parallela culebrensis, Urocoptis producta, Varicella angiostoma ingallsiana, Zachrysia auricoma. Species that were rated as ‘probably extinct’ in the model assessment are printed in bold. Both in the model and the expert approach the number of species that are qualified as ‘unable resp. not possible to assess’ is relatively high. So the lack of knowledge about the conservation status of land molluscs is still at an alarming level. Given the methodology used this is also a pregnant result of this important study.

Reference:
Régnier, C., Achaz, G., Lambert, A., Cowie, R., Bouchet, P. & Fontaine, B., 2015. Mass extinction in poorly known taxa. – Proceedings of the National Academy of Sciences of the United States of America. Published online before printJune 8, 2015, doi:10.1073/pnas.1502350112  (see Full Text (PDF)).

Various new papers

Several new papers on Neotropical snails did appear recently, with emphasis on Cuba and Brazil (decidedly the most active malacological societies).

Cuban papers were published in a new issue of the journal ‘Solenodon’ and focus mainly on Cerionidae.

Suárez studied the reproductive cycle of Cerion mumia chrysalis Férrusac, 1837. “Gonads of 144 mature specimens of Cerion mumia chrysalis were examined. Between January-December, 2012 were collected 12 specimens per month. Two reproductive cycles were recognized, one from January to April, and another from July to September. Both male and female reproductive cells were observed inside the acini, which defines the species as hermaphrodite. During May-June and subsequently in October-November no follicular activity was observed. In December, the acini decreased notably in size”.

Suarez 2015

Suárez et al. published on the effect of hurricanes on molluscs. “Data about the conservation status on mollusk populations of Cerion dimidiatum Pfeiffer, C. scalarinum Pfeiffer and Gundlach, C. torrei moralesi Clench and Aguayo, C. p. paucicostatum Torre, and C. orientale Clench and Aguayo, local endemics from Eastern Cuba are given. Populations were affected by the hurricanes hazard, been obtained values of 0.4 ind/m2; 0. 37 ind/m2; 0.04 ind/m2; 0.16 ind/m2 and 0.03 ind/m2 respectively”.

Two papers related to distribution. Fernández et al. (2015a) published on “the geographic distribution range of Cerion saetiae Sánchez Roig, 1948 was widened, with two new records: Playita de Fidel in Saetía key and Baracutey beach from El Ramón de Antilla peninsula. It presence was corroborated at type locality. Abundance and lineal dimensions variability of shell are explained”.

Fernandez et al 2015a

Fernández et al. (2015b) made “a study about terrestrial mollusks in altitudinal levels and different rocky substrata in Sierra de Nipe. Thirty new records from Sierra of Nipe and adjacent heights are presented. Twenty-six localities were visited; among them seven on serpentine rocks between 400-1000 masl, 19 localities on calcareous substratum from 100- 400 masl and eight localities were taking from published papers. One hundred fourteen species were recorded, constituting 8.2% of the Cuban fauna thereby reaching the second more diverse place in Cuba, after Viñales; therefore representing 57.3% of those known species at Nipe-Sagua-Baracoa. On calcareous substratum 113 species were recorded while on serpentine were 25, most of them also on calcareous soils, except Caracolus n. sp. Part of this terrestrial mollusks “hotspot” is protected by the National Park Mensura-Piloto”.

Fernandez et al 2015b

Finally, I like to mention a recent paper by Simone on the bulimulid genus Kora, with description of new species. The abstract reads “Three new species of the recently described genus Kora are described, based on dry material collected in caverniculous and adjacent environments. Kora terrea, from Presidente Olegdrio, MG, is characterized by spotted pigmentation; projected, wide outer lip, and pointed spire. Kora nigra, from Carinhanha, BA, is characterized by dark-brown color, elliptical outline, and rounded, narrow aperture. Kora iracema, from Sao Desidério, BA, is characterized by very ample, projected outer lip, wide spire and white coloration. A new occurrence of the type species, Kora corallina, is reported, from Carinhanha, BA, expanding its geographic distribution ~200km towards southwest. Species of the genus Kora have been shown to be restricted to semi-dry, caatinga environment, restricted to south region of Northeast Brazilian region, and north of Southeast region”.

Simone 2015

References:
Fernández, A., Franke, S., Suárez, A. & Hernández, I., 2015a. Registros nuevos, abundancia y morfometría de Cerion saetiae (Mollusca: Pulmonata) en la provincia Holguín, Cuba. – Solenodon 12: 28-32.
Fernández, A., Frenke, S., Espinosa, J., Reyes, E., Sigaretta, S., Matos, A. & Rodríguez, Y., 2015b. Moluscos terrestres (Mollusca: Gastropoda) en Sierra de Nipe y alturas adyacentes, Cuba. – Solenodon 12: 38-56.
Simone, L.R.L., 2015. Three new species of Kora (Pulmonata, Orthalicidae) from Bahia and Minas Gerais, Brazil. – Journal of Conchology 42: 51-56.
Suárez, A., 2015. Ciclo reproductivo de Cerion mumia chrysalis (Pulmonata: Stylommatophora: Cerionidae). – Solenodon 12: 21-27.
Suárez, A., Hernández, I., Morales, A. & Fernández, A., 2015. Densidad de algunas poblaciones de ceriónidos (Mollusca: Gastropoda: Cerionidae) de la región oriental de Cuba, recientemente afectada por huracanes. – Solenodon 12: 33-37.

[The Solenodon issue is available here]