Sunday, April 30, 2017

[Mollusca • 2017] Minaselates paradoxa • A New Genus and New Species of Epiphragmophoridae from Brazil (Gastropoda: Stylommatophora: Helicoidea)

Minaselates paradoxa
Cuezzo & Pena, 2017 

We describe a new genus and a new species in the family Epiphragmophoridae, Minaselates paradoxa sp. n. The new species was found at the National Park Cavernas do Peruaçu, in northern portion of the state of Minas Gerais, Brazil. Minaselates paradoxa sp. n. is classified in Epiphragmophoridae based on the fact that it shares the following diagnostic features of the family: a dart apparatus with a single dart sac, and two unequal mucous glands at the terminal genitalia. Minaselates gen. n. differs from Epiphragmophora Doering, 1874 by having a granulose protoconch, shell spire with blunt apex, complex microsculpture on the teleoconch and closed umbilicus fused with the shell wall. Also, significant differences between the two genera are the presence of a long and thin kidney that extends more than half the length of the pulmonary cavity, the presence of a flagellar caecum, and a smooth jaw in Minaselates gen. n. The finding of this new species and genus is particularly significant to refine the definition of the family, since Epiphragmophoridae has been traditionally diagnosed using the same characters of Epiphragmophora. Dinotropis Pilsbry & Cockerell, 1937, the other valid genus in the family, is monospecific and is only known by the morphology of the shell. In many ways it is similar to Epiphragmophora. A cladistics analysis was made in the present study which supports Minaselates gen. n. as a different entity and as sister group of the Epiphragmophora within Epiphragmophoridae.

Key words: Cerrado, Pleurodontidae, Pulmonata, South America, Taxonomy

Figures 2–7. Minaselates paradoxa sp. n. Shell morphology:
(2) Dorsal view of Holotype, MNRJ 34.580; (3) lateral position of holotype shell and soft body; (4) dorsal, (5) ventral, and (6) lateral view of paratype, IBN 861; (7) live snail.
Scale bar: 3–5 = 10 mm.   DOI: 10.3897/zoologia.34.e13230  

Class Gasteropoda Cuvier, 1795

Clade Heterobranchia Burmeister, 1837
Clade Stylommatophora Schmidt, 1855

Superfamily Helicoidea Rafinesque, 1815
Epiphragmophoridae Hoffmann, 1928

Minaselates gen. n.

 Diagnosis: Minaselates gen. n. is distinguished by the following characters: 1) shell globose with blunt apex; 2) protoconch sculptured with granules; 3) teleoconch sculptured with complex microstructures; 4) umbilicus imperforate, parietal wall fused with columellar zone of peristome; 5) wavy spiral lines below the periphery and over ventral teleoconch surface; 6) genitalia with a dart apparatus composed by a single dart sac and two unequal mucous glands, one globose and the other oval; 7) presence of a flagellar caecum; 8) bursa copulatrix duct short, no longer than the sac.

Type species: Minaselates paradoxa sp. n. by original designation.

Description: Shell globose, with 4 to 5 convex whorls. Spire conic with blunt apex. Protoconch granulose. Teleoconch sculptured. Wavy spiral grooves at the ventral teleoconch surface. Aperture subcircular with thin peristome. Umbilicus closed. Presence of spiral brownish bands more pronounced in the body whorl. Kidney long and thin, more than half the lung roof length. Genitalia with a dart apparatus and two unequal mucous glands.

Etymology: Minaselates is a compound name formed by Minas in honor to the Brazilian state where the species was found, and selates, a noun in the genitive singular, that derives from the Greek meaning “snail” (Brown 1979).

Remarks: Minaselates gen. n. is classified in Epiphragmophoridae because it has a dart apparatus and two unequal mucous glands at the terminal genitalia. These structures are diagnostic of Epiphragmophoridae (Helicoidea) and their morphology serve to differentiate this family from the remaining helicoidean groups. Dinotropis differs from Minaselates in its depressed shell with an acute peripheral keel and open umbilicus. Minaselates differs from Epiphragmophora in its general shell shape with blunt apex, granulose protoconch and complex sculpture of the teleoconch surface. The wavy spiral grooves at the ventral teleoconch surface in Minaselates are lacking in both, Epiphragmophora and Dinotropis. The presence of a long and thin kidney in Minaselates is very different to the kidney shape in Epiphragmophora, which is triangular and shorter.

Minaselates paradoxa sp. n.

Diagnosis: Shell globular, with three spiral continuous pigmented bands, the middle, equatorial band thinner. Protoconch granulose. Dorsal side of teleoconch with axial lines bearing triangular lamellae, ventral teleoconch with wavy, concentric, spiral grooves. Imperforate umbilicus. Jaw smooth. Kidney triangular, long and thin, of about 60 to 70% the length of the lung roof. Vas deferens insertion in lower portion of flagellar caecum. Strong, short muscular penial retractor inserting at proximal epiphallus.

Etymology: The species name derives from the Greek paradoxos meaning “strangecontrary to expectation” (Brown 1979) as this is a species of Epiphragmophoridae that was not expected to occur in the state of Minas Gerais, Brazil.

Type locality: Brazil, Minas Gerais: Itacarambi, National Park Cavernas do Peruaçu, Vale dos Sonhos (523m, X = 0599645, Y = 8343426), M.S. Pena, A. Suhett, D.C. Souza leg., December 2010, (MNRJ 34.580), Holotype (ethanol preserved specimen).

Distribution: Thus far known only from National Park Cavernas do Peruaçu, northern region of Minas Gerais, Brazil.

 Maria Gabriela Cuezzo and Meire Silva Pena. 2017. Minaselates, A New Genus and New Species of Epiphragmophoridae from Brazil (Gastropoda: Stylommatophora: Helicoidea).   Zoologia. 34; 1-12.  DOI: 10.3897/zoologia.34.e13230

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