Tag Archives: streptaxidae

Bahia snails

Recently Alex Popovkin send me some new photos of snails he found alive during his botanical wanderings. As always these pictures don’t allow for definite identifications, but here is my best guess.

1-P1560547 2-P1560548 3-P1560550 4-P1560552 5-P1560553

Helicina angulata Sowerby, 1873

1-P1560554 2-P1560555 3-P1560556 4-P1560558

 

A Rectartemon species, possibly R. iguapensis (Pilsbry, 1930) or R. piquetensis (Pilsbry, 1930).

A big thanks to Alex for sharing…

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New snails from Brazil, Edo. Tocantins

The Brazilian state of Tocantins is relatively less-known, partly due to being a split-off of Goiás state. Since its Cerrado domain has been poorly studied, a paper by Salvador et al. (2015) is a welcome addition to our knowledge.

A sample of land snails, mainly pulmonates, was recently collected in southeastern Tocantins state, Brazil, close to the border with Bahia state. The following species were found in the material, all of them are reported for the first time from Tocantins: Helicina schereri (Helicinidae); Solaropsis fairchildi and Solaropsis rosarium (Camaenidae); Anostoma rossiCyclodontina cf. gemellata and Cyclodontina sectilabris (Odontostomidae); Drymaeus poecilus and Naesiotus carlucioi (Bulimulidae); Streptaxis luetzelburgi (Streptaxidae); Megalobulimus conicus (Strophocheilidae); Beckianum cf. beckianum (Subulinidae). Additionally, Drymaeus dakryodes sp. nov. is formally described herein. The new records and species addressed here constitute important findings, helping to fill distributional gaps and improving the knowledge of the local molluscan fauna. This is an essential step for future conservation efforts.

Salvador etal 2015 f15-23

The new Drymaeus species was found at Taguatinga, 12º21’54”S 46º21’39”W, ~870m. The holotype (fig. 15-16) is MZSP 114874. The specimen of Beckianum beckianum is a sinistral shell, and other sinistral specimens have been reported from Central America.

Reference:
Salvador, R.B., Cavallari, D.C. & Simone, L.R.L., 2015. Taxonomical study on a sample of land snails from southeastern Tocantins State, Brazil, with description of a new species. – Journal of Conchology 42: 67-78.

Serra da Capivara

Earlier in 2013 Simone & Casati published a paper on a series of shells from a relatively unknown region in Brazil, the Serra da Capivara.

The abstract is: “Five new species and one new genus are described from the Serra da Capivara, Piauí, Brazil, a region of semi-dry, Caatinga environment. The described taxa are: Odontostomidae: 1) Clinispira insolita, n. gen. n. sp., possessing strange spire inclination and aperture approaching to the shell apex, it looks closely related to Anostoma, Tomigerus and Biotocus; 2) Cyclodontina capivara n. sp., with well-developed axial ribs and 6 teeth at peristome; 3) Anctus prolatus n. sp., very elongated, with aperture lacking teeth; Simpulopsidae: 4) Rhinus gilbertus n. sp., somewhat elongated and relatively well-sculptured; Streptaxidae: 5) Streptartemon molaris n. sp., possessing a very large basalis tooth at peristome. Two subulinids are also reported from the region: 6) Beckianum beckianum (Pfeiffer, 1846), a population with peculiar pointed shell apex and well-developed axial sculpture; 7) Lamellaxis cf. gracilis (Hutton, 1834), a wide-ranged species that merits further investigation. These descriptions show how scanty is our knowledge on northeast Brazilian malacofauna and may raise efforts for its preservation.” All material comes from the same locality, Cave Toca de Cima dos Pilão, Coronel José Dias municipality.

Simone2013f2-6

Clinispira insolita n. gen. n. sp.

Simone2013f16-18

Cyclodontina capivara n. sp.

Simone2013f35-37

Anctus prolatus n. sp.

Simone2013f24-26

Rhinus gilbertus n. sp.

Simone2013f46-47

Streptartemon molaris n. sp.

The new, monotypic genus Clinispira is especially noteworthy, and maybe other species may turn up once this region is better investigated. The study of living specimens should clarify the relationships of the new taxa described by morphological and molecular studies.

Reference:
Simone, L.R.L. & Casati, R. (2013). New land mollusk fauna from Serra da Capivara, Piauí, Brazil, with a new genus and five new species (Gastropoda: Orthalicoidea, Streptaxidae, Subulinidae). – Zootaxa 3683: 145–158.

Photo of the day (143): Streptaxis ?

Today something puzzling.

Alex Popovkin, field botanist in northeastern Bahia, send me several pictures for identification.

This is definitely a subadult, possibly of Streptaxis costulosus (Pfeiffer, 1852), which is known to occur in Bahia. The closest I can get I think…

Thanks Alex!

Anatomy of Huttonella bicolor

Luiz Simone, very good at snail anatomy, has just published a paper on the anatomy of the streptaxid Huttonella bicolor. This is an invasive species in Brazil.

The abstract reads: The morpho-anatomy of the micro-predator Huttonella bicolor (Hutton, 1838) is investigated in detail. The species is a micro-predator snail, which is splaying in tropical and sub-tropical areas all over the world, the first report being from the Amazon Rainforest region of northern Brazil. The shell is very long, with complex peristome teeth. The radula bears sharp pointed teeth. The head lacks tentacles, bearing only ommatophores. The pallial cavity lacks well-developed vessels (except for pulmonary vessel); the anus and urinary aperture are on pneumostome. The kidney is solid, with ureter totally closed (tubular); the primary ureter is straight, resembling orthurethran fashion. The buccal mass has an elongated and massive odontophore, of which muscles are described; the odontophore cartilages are totally fused with each other. The salivary ducts start as one single duct, bifurcating only prior to insertion. The mid and hindguts are relatively simple and with smooth inner surfaces; there is practically no intestinal loop. The genital system has a zigzag-fashioned fertilization complex, narrow prostate, no bursa copulatrix, short and broad vas deferens, and simple penis with gland at distal tip. The nerve ring bears three ganglionic masses, and an additional pair of ventral ganglia connected to pedal ganglia, interpreted as odontophore ganglia. These features are discussed in light of the knowledge of other streptaxids and adaptations to carnivory.

Reference:
Simone, L.R.L., 2013. Anatomy of predator snail Huttonella bicolor, an invasive species in Amazon rainforest, Brazil (Pulmonata, Streptaxidae). Papeis Avulsos de Zoologia 53 (3): 47-58.Available at http://bit.ly/YLI1gF.

Streptaxid phylogeny

A recent study across the superfamily Streptaxoidea (Rowson et al., 2011) reveals a complicated pattern of relationships within this group which is widely distributed in the tropics. Neotropical members are relatively scarce (Bolivia, Paraguay, Brazil, Guyanas, Venezuela, and Lesser Antilles), and for this study two Brazilian species have been used.

Schermafbeelding_2011-03-01_om

An interesting pattern emerges in the phylogenetic tree, with the previously recognized subfamilies within the Streptaxidae being polyphyletic. At the basis of this family, in all analyses a persistent polytomy was obtained. Divergence times, historical biogeography, and the available fossils (the Miocene Brasilennea for the Neotropics) all suggest a Cretaceous origin of the group. There is evidence for multiple transoceanic, Cenozoic dispersals followed by radiations, including at least two from Africa to South America. Such colonisation events may also be suspected in other tropical land-snail families.

While this study opens the way for a thorough reclassification of mainly the African Streptaxid members, it thus also includes some provocative ideas about the origin of tropical and southern temperate land-snail faunas. 
Food for thought…

Afbeelding_1_09-12-18
Reference:
Rowson, B., Tattersfield, P., Symondson, W.O.C., 2011. Phylogeny and biogeography of tropical carnivorous land-snails (Pulomonata: Streptaxoidea) with particular reference to East Africa and the Indian Ocean. – Zoologica Scripta 40: 85-98.