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Taxonomical study on a sample of pulmonates from Santa Maria da Vitória, Bahia, Brazil, with description of a new genus and four new species (Mollusca: Orthalicidae and Megalobulimidae)

Abstracts

A sample of Pulmonata collected in Santa Maria da Vitória, interior of Bahia, Brazil, in Caatinga semi-arid environment, is studied taxonomically. From the five species, four are revealed as new, including a new genus. The new taxa are the Bulimulidae (1) Kora corallina gen. et sp. n. characterized by the elongated shell with aperture somewhat dislocated from the shell axis, and an oblique tooth in middle level of inner lip; (2) Spixia coltrorum, mainly characterized by an uneven spire, delicate sculpture and peristome with 4 equidistant teeth; (3) Anostoma tessa, mainly characterized by a broad spire and well-developed anal canal; and the Megalobulimidae (4) Megalobulimus amandus, mainly characterized by pointed protoconch sculptured by dense quantity of axial cords. Rhinus suturalis is the only previously known species, but its geographic distribution is expanded southwards to Bahia state. A discussion with respect to necessity for improving the study on the malacofauna from the interior region of the Brazilian Northeast and the importance for preservation of the Caatinga biome is also provided.

Northeast Brazil; Caatinga; Stylommatophora; Megalobulimus; Anostoma; Spixia; Kora new genus


Uma amostra de Pulmonata coletada em Santa Maria da Vitória, interior da Bahia, Brasil, na Caatinga semiárida, é estudada taxonomicamente. Das 5 espécies, 4 revelaram-se novas, incluindo um gênero novo. Os táxons novos dão os Bulimulidae (1) Kora corallina gen. et sp. n. caracterizado pela concha alongada com apertura algo deslocada do eixo da concha e um dente oblíquo no nível médio do lábio interno; (2) Spixia coltrorum, principalmente caracterizado pelas voltas desiguais da espira, escultura delicada e perístoma com 4 dentes equidistantes; (3) Anostoma tessa, principalmente caracterizado pela espira bojuda e um canal anal bem desenvolvido; e pelo Megalobulimidae (4) Megalobulimus amandus, principalmente caracterizado pela protoconcha pontuda esculturada por uma densa quantidade de cordas axiais. Rhinys suturalis é a punica espécie previamente conhecida, mas sua distribuição geográfica é expandida para o sul até a Bahia. Uma discussão a respeito da necessidade de melhoria do estudo sobre a malacofauna do interior do Nordeste e a importância da preservação do bioma Caatinga é também fornecida.

Nordeste do Brasil; Caatinga; Stylommatophora; Megalobulimus; Anostoma; Spixia; Kora gênero novo


Taxonomical study on a sample of pulmonates from Santa Maria da Vitória, Bahia, Brazil, with description of a new genus and four new species (Mollusca: Orthalicidae and Megalobulimidae)

Luiz Ricardo L. Simone

Museu de Zoologia, Universidade de São Paulo. Caixa Postal 42.494, 04218‑970, São Paulo, SP, Brasil. E‑mails: lrsimone@usp.br; lrlsimone@gmail.com

ABSTRACT

A sample of Pulmonata collected in Santa Maria da Vitória, interior of Bahia, Brazil, in Caatinga semi-arid environment, is studied taxonomically. From the five species, four are revealed as new, including a new genus. The new taxa are the Bulimulidae (1) Kora corallina gen. et sp. n. characterized by the elongated shell with aperture somewhat dislocated from the shell axis, and an oblique tooth in middle level of inner lip; (2) Spixia coltrorum, mainly characterized by an uneven spire, delicate sculpture and peristome with 4 equidistant teeth; (3) Anostoma tessa, mainly characterized by a broad spire and well-developed anal canal; and the Megalobulimidae (4) Megalobulimus amandus, mainly characterized by pointed protoconch sculptured by dense quantity of axial cords. Rhinus suturalis is the only previously known species, but its geographic distribution is expanded southwards to Bahia state. A discussion with respect to necessity for improving the study on the malacofauna from the interior region of the Brazilian Northeast and the importance for preservation of the Caatinga biome is also provided.

Key-Words: Northeast Brazil; Caatinga; Stylommatophora; Megalobulimus; Anostoma; Spixia; Kora new genus.

RESUMO

Uma amostra de Pulmonata coletada em Santa Maria da Vitória, interior da Bahia, Brasil, na Caatinga semiárida, é estudada taxonomicamente. Das 5 espécies, 4 revelaram-se novas, incluindo um gênero novo. Os táxons novos dão os Bulimulidae (1) Kora corallina gen. et sp. n. caracterizado pela concha alongada com apertura algo deslocada do eixo da concha e um dente oblíquo no nível médio do lábio interno; (2) Spixia coltrorum, principalmente caracterizado pelas voltas desiguais da espira, escultura delicada e perístoma com 4 dentes equidistantes; (3) Anostoma tessa, principalmente caracterizado pela espira bojuda e um canal anal bem desenvolvido; e pelo Megalobulimidae (4) Megalobulimus amandus, principalmente caracterizado pela protoconcha pontuda esculturada por uma densa quantidade de cordas axiais. Rhinys suturalis é a punica espécie previamente conhecida, mas sua distribuição geográfica é expandida para o sul até a Bahia. Uma discussão a respeito da necessidade de melhoria do estudo sobre a malacofauna do interior do Nordeste e a importância da preservação do bioma Caatinga é também fornecida.

Palavras-Chave: Nordeste do Brasil; Caatinga; Stylommatophora; Megalobulimus; Anostoma; Spixia; Kora gênero novo.

INTRODUCTION

The internal region of the Brazilian Northeast is a challenging place. A dry environment and hostile vegetation, called Caatinga, contrasts with the normal background of the much more famous rainforests, such as the Amazon and Atlantic. However, the native high mollusk diversity is an intriguing enigma, which is only comparable with the high level of ignorance about the local malacofauna.

This paper deals with a case of a collection done by the team of the shell dealer José Coltro Jr. in Santa Maria da Vitória, a small neighborhood in the interior of Bahia. Most of the species in this collection are unknown and undescribed, and there is even a new genus. This paper is a formal description of these taxa, and is part of a wider project to inventory the Brazilian malacofauna. As part of that project, a complete inventory of the known species has been published (Simone, 2006), which facilitates the subsequent detection and description of new species.

This paper deals with members of two families, the Orthalicidae (= Bulimulidae), which is the more diverse from the Brazilian land snails, with 286 valid species, and a Megalobulimidae (possibly = Acavidae), with 62 species in its single genus Megalobulimus Miller, 1878, the second more diverse.

This paper also has the objective of showing that the semi-arid regions of the interior of the Brazilian Northeast have great centers of endemism, which deserve biodiversity preservation and protection.

MATERIAL AND METHODS

The list of material examined follows each species description. The examined specimens are only dry shells, as no complete specimens have been collected. The lots are all deposited in institutional collections, with the following abbreviations: MNHN, Museé National d'Histoire Naturelle, Paris; MNRJ, Museu Nacional da Universidade Federal do Rio de Janeiro; MZSP, Museu de Zoologia da Universidade de São Paulo; USNM, National Museum of Natural History, Smithsonian Institution, Washington D.C.

Systematics

Family Orthalicidae

Genus Kora new genus

Diagnosis: Outline fusiform; spire tall, somewhat turriform. Protoconch simple, paucispiral, ornamented by scanty axial cords. Umbilicus narrow. Peristome somewhat away from longitudinal axis of spire. Peristome deflected. Inner lip with strong, oblique tooth in middle level.

Gender: Feminine.

List of included taxa: Kora corallina new species.

Etymology: The generic epithet refers to the aperture form, looking like a crown in spire, a contraction of the Latin word Corona = crown, corpse, with first letter changed to K to avoid homonymy.

Kora corallina new species

(Figs. 1‑8)


Types: Holotype MZSP 103910.

Paratypes: MZSP 103911, 1 shell; MZSP 103912, 1 shell, USNM, 2 shells; MNRJ, 2 shells; NMHN, 2 shells; MZSP 103913, 32 shells; all from type locality.

Type locality: BRAZIL. Bahia; Santa Maria da Vitória, ~13°24'S, 44°12'W, ~460 m of elevation (Coltro col., i/2012).

Description: Shell up to 45 mm, outline fusiform, elongated, ~2.3 longer than wide. Color white in first whorls, gradually brown pigment appearing, becoming darker in last whorl; peristome white, sometimes with brown spots in inferior region. Protoconch (Fig. 5) with 2 whorls, somewhat pointed; length ~7% of shell length, and ~16% of shell width; mostly smooth, barely sculptured by axial riblets. Limit between protoconch and teleoconch weakly visible, orthocline. Teleoconch of ~5 whorls successively and uniformly increasing; profile almost straight, weakly concave; suture feebly deep; sculpture absent, except for growth lines and delicate axial, uniform undulations, ~55 in penultimate whorl (Figs. 3, 4). Peristome deflected, except for region of callus. Callus low, weak (Figs. 1, 7, 8). Aperture wide, somewhat dislocated from spire longitudinal axis; length ~44% of shell length, ~70% of shell width. Outer lip inserted distantly from adjacent suture, simple, arched. Inner lip strongly concave, superior half weakly convex, mostly showing outer surface of last whorl; inferior half almost straight, concave only inferiorly; bearing oblique tooth, as short fold, in limit with superior half, making peristome width with almost double width of remaining regions (Figs. 1, 2, 7, 8); tooth length ~28% of peristome length. Umbilicus present, narrow, partially covered by inferior half of inner lip (Fig. 6).

Measurements (in mm): Holotype: 43.4 by 22.3; Paratypes MZSP 103911: 42.9 by 22.4; MZSP 103912: 48.9 by 23.6.

Distribution: Known only for type locality.

Habitat: Caatinga environment.

Material examined: Types.

Etymology: The specific epithet refers to the outline of the shell, resembling a coral polyp, from the Latin corallium. The name is also a regard to Cora Coralina, the pseudonym of Ana Lins dos Guimarães Peixoto Bretas (1889‑1985), a famous Brazilian poet novelist.

Discussion: The peculiar characters of Kora corallina, if compared with all species of South American land malacofauna, allowed the designation of a new genus. Initially, the first identification was some species of Thaumastus Albers 1860. However, the Brazilian Thaumastus are much larger. Although some species from the Andes are of smaller size, no small-sized Thaumastus has so far been found in Brazilian territory. Besides, Kora differs in having a sharper protoconch, a more projected peristome, the tooth in inner lip and a clear umbilicus (Figs. 2, 6). Kora is also somewhat similar to Neopetraeus von Martens, 1885, so far restricted to the Andes region. It differs from Neopetraeus mainly by the tooth in middle level of inner lip, which is absent in all species. Additionally, it differs by the simpler fashion of the protoconch sculpture (Neopetraeus has nepionic sculpture of delicate vertical riblets with spiral striae in the intervals), and in lacking carinated young shells (Pilsbry, 1897:163).

The inner tooth in middle level of inner lip of K. corallina (Figs. 1, 2, 7, 8) is similar to some species of Dryptus Albers, 1860 [e.g., D. rhodocheilus (Reeve, 1849)], Plekocheilus Guilding, 1823 (e.g., P. nebulosus Breure, 2009), and all species of Eudolichotis Pilsbry, 1896 (Simone, 2006). This character possibly approaches Kora from those genera, which someday can be used for separating them from the other orthalicid genera in a proper subfamily or tribe.

The degree of shell variation of Kora corallina is not high. The holotype shape (Figs. 1‑3) is that found in most specimens. Extreme variation patterns are represented in Figs. 7 and 8. In Fig. 7 is represented a wide specimen with more rounded whorls and aperture. In Fig. 8 is represented the more elongated specimen, in such aperture becomes still more dislocated to right from shell axis.

Genus Spixia Pilsbry & Vanata, 1898

Spixia coltrorum new species

(Figs. 9‑14)

Types: Holotype MZSP 103920.

Paratypes: MZSP 103922, 2 shells; MZSP 103921, 1 shell, USNM, 1 shell; MNRJ, 1 shell; MZSP 103923, 8 shells; all from type locality.

Type locality: BRAZIL. Bahia; Santa Maria da Vitória, ~13°24'S, 44°12'W, ~460 m of elevation (Coltro col., i/2012).

Diagnosis: Shell with superior half clearly narrower than inferior half, in a non-uniform growth. Sculpture of delicate, uniform axial riblets, opaque surface. Peristome partially projected, with 4 teeth of somewhat same size and equidistant.

Description: Shell up to 45 mm; outline somewhat turriform, elongated; width ~36% of length (Figs. 9‑11). Color white, with scanty axial pale brown spots randomly distributed in last whorls. Protoconch of 2 rounded whorls, sculptured by delicate reticulate of spiral and axial lyre; each cord very narrow and low, separated from each other by distance equivalent to 3‑times its width; both spiral and axial cords predominating or a weak predominance of axial cords (Fig. 13); limit with teleoconch unclear; mostly eroded and absent amongst specimens (Fig. 11). Teleoconch of more than 8 whorls; whorls profile almost straight, weakly convex; suture weakly deep. Sculpture a series of delicate and uniform axial riblets, ~110 in penultimate whorl. Superior half of spire clearly narrower than inferior half, marked by a somewhat abrupt increase, whorls not uniformly growing (Figs. 9‑10). Last whorl uniform with preceding whorls, marked by pair of grooves 1/6 whorl preceding peristome, corresponding to teeth of outer lip; anterior most groove weakly deeper than posterior groove (Fig. 12). Peristome oval, deflected, with ~32% of shell length and ~73% of shell width; weakly prosogyre (Fig. 10). Outer lip arched, with short straight middle region; inner lip strongly concave, superior half weakly convex, covered by thin callus with similar width than remaining peristome. Peristome with 4 teeth of somewhat similar size and equidistant from each other (Figs. 9, 11); parietal tooth located approximately at middle region of callus; palatal tooth located just anterior to middle inflexure of inner lip, this tooth largest; two teeth in outer lip, one located in its middle level, another located slightly at right from anterior corner, this tooth being smallest. Umbilicus opened, narrow, partially covered by inferior half of inner lip, flanked by blunt oblique fold running parallel to furrow of anterior peristome tooth (Figs. 12, 14).

Measurements (in mm): Holotype: 40.0 by 16.0; Paratype MZSP 103921: 40.6 by 16.2.

Distribution: Known only for type locality.

Habitat: Caatinga environment.

Material examined: Types.

Etymology: The specific epithet is in honor of the Coltro brothers, José and Marcus, who contribute greatly with study material, including the present one.

Discussion: The genus Spixia so far comprised four species (Simone, 2006:172), all of relatively large size, and with entire, rounded peristome, possessing 4 well-developed teeth, which characterizes the genus. From the species, the most similar is Spixia striata (Spix, 1827), from which S. coltrorum differs by wider umbilicus, opaque surface, more acuminate spire, and by proportionally larger aperture. A single species was never figured, S. hillairii (Gray in Pfeiffer, 1845), but according to the description, S. coltrorum differs by the white peristome (S. hillairii has it pink), in having more teleoconch whorls (S. hillairii has 6.5 whorls), and in lacking so developed sculpture (Pfeiffer, 1845:84). S. coltrorum differs from S. charpentieri Pfeiffer, 1850 in being larger, in having sharper pointed aspire, narrower protoconch, and in lacking fifth tooth in outer lip. S. coltrorum still differs from S. paraguayana (Ancey, 1892) by less developed peristome, by paler color, and by less developed axial sculpture.

The interesting axial brown spots somewhat randomly disposed in the spire (Figs. 9‑11) is a current feature amongst the odontostomines, and well developed in S. coltrorum. One of the main features of the species, the different growth between superior and inferior halves of the spire, is very clear in holotype (Figs. 9‑10), while it is not so clear in other species (Fig. 11). Other interesting finding is the loss of the protoconch in most specimens (Fig. 11). From the examined ones, only 3 of them possess preserved protoconch. The structure is fractured in the remaining specimens, with a calcified scar.

Genus Anostoma Waldheim, 1807

Anostoma tessa new species

(Figs. 15‑20)


Types: Holotype MZSP 103914.

Paratypes: MZSP 103915, 1 shell; USNM, 2 shells; MNRJ, 2 shells; NMHN, 2 shells; MZSP 103916, 37 shells; all from type locality.

Type locality: BRAZIL. Bahia; Santa Maria da Vitória, ~13°24'S, 44°12'W, ~460 m of elevation (Coltro col., i/2012).

Diagnosis: Shell with tall spire (spire ~60% of length). Aperture wide, with tall teeth. Anal canal well-developed, turned backwards. Callus reaching shell apex.

Description: Shell discoid, lenticular, up to 32 mm. color white, with irregular small spots sometimes coalescent, forming barely bands in rather spiral pattern (Figs. 16, 18). Spire ~55% of length and ~40% of height. Protoconch simple, almost plane, white, opaque; 1.5 weakly convex whorls; limit with teleoconch unclear; occupying ~10% of shell length and almost zero of its height (Figs. 15, 18, 20). Teleoconch with ~4.5 whorls; whorls weakly convex, suture shallow; in conjunct whorls forming wide dome. Sculpture weak, mainly constituted by axial undulations, ~33 in penultimate whorl; body whorl with delicate hammer-like marks in periphery in ~50% of specimens, and weak axial undulations; inferior surface (fig. 16) possessing weak axial undulations with scanty delicate hammer-like marks. Peripheral carina very weak, almost absent (Figs. 17, 18), mainly visible in opposite side than aperture. Pair of wide furrows gradually appearing ~20% of shell length posterior to peristome in dorsal surface of pre-peristome region (Figs. 16, 17); both ending in wide furrow formed by peristome expansion (Fig. 16). Peristome complete, thick, mainly in outer lip (Figs. 15, 19, 20), occupying from ~72 to ~60% of shell width and ~30% of shell length; 5 complete teeth, somewhat similar and equidistant with each other; height of each tooth ~50% of aperture width and about as wide as peristome lip; all teeth arched, with concavity turned to right or posteriorly; anal canal well distinct (Figs. 15, 19, 20), flanked by pair of folds, posterior fold simple, curved, thin and relatively low, located somewhat perpendicularly to right parietal tooth, anterior fold double, in conjunct somewhat similar to posterior tooth, except in being situated more obliquely. Anal canal clearly tuned backwards, ~40‑45° in relation to longitudinal axis of shell. Callus thin, rounded, simple, reaching shell apex or close to it (Figs. 15, 18, 20).

Measurements (in mm): Holotype: 31.1 by 24.5; paratype MZSP 103915: 31.1 by 23.5.

Distribution: Known only for type locality.

Habitat: Caatinga environment.

Material examined: Types.

Etymology: The specific epithet refers to the Tupi native language in such tessa means eye, an allusion for the form of the shell.

Discussion: Anostoma tessa is only similar to Anostoma baileyi Solem, 1956, the single species so far possessing a clear demarcated anal canal at aperture, but it differs in having this anal canal turned posteriorly, while that of A. baileyi is turned right of even anteriorly; in having a taller spire (spire is ~55% of length, while it is ~45% in A. baileyi); in having wider callus, reaching the shell apex (while the callus of A. baileyi covers slightly more than half of distance between inner lip and shell apex). The other Anostoma-like species that are also anal canal bearing is Ringicella luetzelburgi Weber, 1925, in such the new species differ in having much less developed apertural teeth, wider aperture, broader callus and taller spire. Most species of the genus Ringicella Gray, 1847 possess anal canal, but, different from that of Anostoma species that bear the canal, the structure forms a tube, opening separately from the shell aperture (Simone, 2006:175, fig. 622).

Anostoma tessa apparently is the broader and more inflated from the Anostoma-Ringicella species, this being a most distinctive feature of the new species. Besides, the presence and form of the anal canal is another exclusivity, it is a quite rare among the Anostoma (only a single species bears it), and it is the rule in Ringicella, but separated in a proper tube. In this feature, A. tessa and A. baileyi are somewhat intermediary between a typical Anostoma and the Ringicella.

Genus Rhinus Martens in Albers, 1860

Rhinus suturalis (Baker, 1914)

(Fig. 21)

Bulimulus (Rhinus) rochai suturalis Baker, 1914:620, 637 (pl. 23, figs. 13‑14) [Mongúba, Ceará & Baturité R.R., ~27 km from Ceará]; Haas, 1939:269; Breure, 1979:131.

Rhinus rochai suturalis: Morretes, 1949:148; Dutra-Clarke & Souza, 1991:291 (pl. 3, fig. 3) [Recife, PE].

Rhinus suturalis: Salgado & Coelho, 2003:163; Simone, 2006:129 (fig. 416).

Types: Holotype ANSP 109322a. Paratype FMNH 14099 (all examined).

Remarks: The shells collected in that Bahia region are conchologically indistinguishable from the type specimens of R. suturalis (Simone, 2006, fig. 416), which so far was known to northern states Ceará and Pernambuco (Baker, 1914; Dutra-Clarke & Souza, 1991). The present report expands the geographic distribution of the species towards the south and east about 800 km. B. suturalis belong to what can be called "complex Rhinus durus (Spix, 1827)", a group of species with obese, short shell which has a relative good anthropic acceptation, commonly found in home gardens and parks throughout Northeastern Brazil. Then, anthropic transportation cannot be completely disregarded.

Material examined: BRAZIL. Bahia; Santa Maria da Vitória, ~13°24'S, 44°12'W, ~460 m of elevation, MZSP 103924, 4 shells (Coltro col., i/2012).

Family Megalobulimidae

Genus Megalobulimus Miller, 1878

Megalobulimus amandus new species

(Figs. 22‑26)

Types: Holotype MZSP 103917.

Paratypes: MZSP 103919, 3 shells; USNM, 1 shells; MNRJ, 1 shells; NMHN, 1 shells; MZSP 103918, 10 shells; all from type locality.

Type locality: BRAZIL. Bahia; Santa Maria da Vitória, ~13°24'S, 44°12'W, ~460 m of elevation (Coltro col., i/2012).

Diagnosis: Shell with less than 80 mm, tip pointed, spire acuminate. Protoconch bearing series of uniform, delicate axial cords. Shell walls relatively thick. Peristome simple, pink to red.

Description: Shell up to 80 mm; outline oval; apex acuminate; width ~60 of length, dorso-ventral height ~50% of shell length. Color mostly pale beige in periostracum-lacking specimens (Figs. 22‑25); some few specimens with periostracum (Fig. 26) somewhat glossy, eroded, presenting mosaic of pale and dark brown bands randomly disposed axially; peristome red to pale pink. Protoconch of ~3 weakly convex whorls, forming a somewhat pointed dome with ~70°; first whorl mostly smooth, opaque, remaining whorls bearing much delicate, uniform, narrow axial cords, ~120 in last nepionic whorl (Fig. 25); each cord running from suture to suture since second whorl, interval between cords very narrow; limit between protoconch and teleoconch barely clear, orthocline. Teleoconch of 2.2 to 2.5 whorls, first whorl with almost straight profile, last whorl more convex than preceding ones. Spite ~60% of shell length. Sculpture similar to that of protoconch, with cords becoming delicate, but well-marked undulations, ~60 in penultimate whorl; ~30% of specimens possessing hammer-like marks in last whorl mid-region (Fig. 24) and region preceding peristome. Peristome complete, normally thick (Figs. 22, 23), glossy, lacking tooth of folds; aperture elliptic, ~54% of shell width, ~50% of shell length. Outer lip simple and rounded. Inner lip feebly concave; no clear separation with callus and parietal region (Figs. 22, 26). Umbilicus extremely narrow to absent.

Measurements (in mm): Holotype: 78.9 by 50.0; paratype MZSP 103919: (1) 69.8 by 40.2; (2) 25.6 by 17.6.

Distribution: Known only for type locality.

Habitat: Caatinga environment.

Material examined: Types.

Etymology: The specific epithet refers to the outline of the shell, resembling a drop. From the Tupi native language from South America, amanda or amana meaning rain or related to rain.

Discussion: Megalobulimus amandus clear belong to the informal complex Megalobulimus oblongus (Müller, 1774) as introduced by Simone & Leme (1998). This complex includes species with deciduous periostracum, peristome normally reddish, sculpture almost exclusively axial strong undulations, and a protoconch also only sculptured by clear axial, uniform undulations or narrow cords. This set of characters can be regarded as the definition of the genus Psiloicus Morretes, 1952, in such M. amandus and remaining M. oblongus complex can someday belong after a deeper revision of the group. A conservative approach is given herein.

Only few of the 62 valid species of Megalobulimus have pointed shell apex (Bequaert, 1948; Leme, 1973; Simone, 2006). This is one of the main characters of M. amandus, as most Megalobulimus in fact possess a more rounded, dome-shaped apex. For this reason, M. amandus only needs to be compared with species from M. oblongus complex with pointed apex. M. amandus differs from M. formicacorsii (Barattini & Ledón, 1949), from Uruguay, in having aperture wider and longer, sculpture shallower, and umbilicus narrower or absent. It differs from M. maximus (Sowerby, 1825), from Amazon, in being much shorter and smaller, by shallower suture, and by reddish peristome. It differs from M. riopretensis Simone & Leme, 1998, from São Paulo, in having narrower aperture, narrower shell width, by more delicate protoconch and teleoconch sculptures, and by less developed umbilicus. It differs from M. wohlersi Morretes, 1952, from Mato Grosso do Sul, by narrower shape, more elongated aperture, shallower suture, broader spire, and more delicate sculpture.

The megalobulimids from Northeastern Brazil normally possess a purple pigmentation in the protoconch and spire first whorls. This is not the case of M. amandus, which has uniform coloration. On the other hand, the species of that region are normally of small size for a Megalobulimus, i.e., below 80 mm, which is the case of the new species. Another interesting feature of M. amandus is the absence of folds and teeth in the peristome, even in more thickened specimens (Figs. 23, 24). Tooth and folds in parietal callus or in middle level of outer lip are common occurrences in species from that region.

A conservative approach is given here considering the genus Megalobulimus in Megalobulimidae Leme, 1973. However, it is recognized that the taxon can possibly be a special branch of Strophocheilidae, and even Acavidae. A project on this matter has been developed, mainly considering phylogenetic methodologies.

DISCUSSION

The amount of four in five species, and one in five genera being new shows how reduced is knowledge on the interior malacofauna of Northeastern Brazil. Still more urgent is the fact that the semi-arid environment of that region has not been the goal of environmentalists and movements for preservation to the same extent as the Amazon and Atlantic rainforests. The richness of species is high, and special attention must be paid to preserving areas of endemism, as well as the odd adaptations of mollusks to semi-arid backgrounds.

Knowledge of the local fauna is the first step in the direction of the aspects mentioned above, which this paper also intends to provide.

On the other hand, except for the new genus, the groups in which the examined samples belong are expected for that region. Some genera have been proven to be endemic to Northeastern Brazil, such as the herein mentioned Rhinus, Anostoma and Spixia, amongst some others not mentioned. The main project, in which the present paper is part, deals with the improvement of the knowledge of biogeographic and evolutionary flows in that specific environment, which certainly influences and is influenced by the aforementioned rainforests.

ACKNOWLEDGMENTS

I extend a special gratitude to Marcus and José Coltro from Femorale for for the collection of the specimens studied herein. Thanks also goes to Bram Breure from Leiden, for opinions and comments on the paper.

Aceito em: 26.10.2012

Publicado em: 20.12.2012

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Publication Dates

  • Publication in this collection
    20 Nov 2012
  • Date of issue
    2012

History

  • Received
    26 Oct 2012
  • Accepted
    20 Dec 2012
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