Research Article |
Corresponding author: Ximena M. C. Ovando ( velliger08@gmail.com ) Academic editor: Edmund Gittenberger
© 2023 Maria Isabel P. F. Macedo, Ximena M. C. Ovando, Sthefane D’ávila.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Macedo MIPF, Ovando XMC, D'ávila S (2023) Redescription and geographical distribution of Leiostracus obliquus (Reeve, 1849) (Mollusca, Gastropoda, Simpulopsidae). ZooKeys 1167: 223-240. https://doi.org/10.3897/zookeys.1167.98707
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Leiostracus Albers, 1850 was established to allocate land snails from Central America and Northern South America. Currently, approximately 19 species are considered valid. However, for most of them, the internal morphology is unknown. Leiostracus obliquus was described as a species of Bulimus from the state of Bahia based on shell characters. Until now, knowledge of this species has been scarce. The discovery of ethanol-preserved specimens from MZSP of this species allowed us to characterize, for the first time, the internal anatomy of this species and update its distribution. The shell of L. obliquus has seven to eight whorls and a wide pale-pink disrupted band all over the teleoconch. The rachidian tooth is small rectangular, symmetric, with round edges, and without differentiated cusps. After comparing the anatomy and radular characters between the shells of L. obliquus and L. carnavalescus, we found remarkable similarities in the morphology and color pattern.
Anatomy, gastropods, land snails, Orthalicoidea, taxonomy
The land snails ascribed to the family Simpulopsidae
Leiostracus was first established to allocate land snails from Central America and Northern South America (Guyana, Suriname, and Brazil) (
The taxonomic history of Leiostracus is controversial, different authors allocate this taxon in generic or subgeneric ranks and ascribe it to different families over time (
Currently, approximately 19 species of Leiostracus are considered valid (
Leiostracus obliquus (Reeve, 1849), was initially described as a species of Bulimus Scopoli, 1777 from Bahia state, Brazil.
During a taxonomic revision of Drymaeus species from Brazil, while analyzing material from two Brazilian malacological collections from Museu de Zoologia de São Paulo and Museu de Malacologia Maury Pinto de Oliveira of Universidade Federal de Juiz de Fora, we found specimens labelled as “Drymaeus sp.” and we noticed that they corresponded to Leiostracus obliquus. Therefore, this work aims to redescribe L. obliquus, providing detailed information on the shell sculpture and internal anatomy. Furthermore, we assessed the geographic distribution of this poorly known species. We also compared the new data to the available information on closely related species.
Specimens were examined from the malacological collections of
Museu de Zoologia de São Paulo (
Radula and jaw were prepared for scanning electron microscopy, following the methodology described by
Digital images of specimens in standardized apertural view (aperture parallel to the camera lens) were used to create Tps files with TpsUtil v. 1.81 software (
To update the geographic distribution of L. obliquus, occurrence data were obtained from literature, and malacological collections consulted from the following sources: Global Biodiversity Information Facility (https://www.gbif.org), Sistema de Informação sobre a Biodiversidade Brasileira (https://www.sibbr.gov.br), the website of malacological collection of the Academy of Natural Science of Philadelphia (https://ansp.org). Despite the loss of the Museu Nacional do Rio de Janeiro’s material in the fire of 2018, the information associated with specimens from this collection remained available on biodiversity databases. We decided to include the occurrence records for L. obliquus from this collection even though we could not confirm species identification, as these specimens were originally identified by Dr. Norma Campos Salgado, a renowned Brazilian malacologist. After removing duplicate records and records without specific localities, we obtained a total of 40 occurrence records, which were georeferenced using Gazetteers and Geolocation applications (https://geo-locate.org/web/WebGeoref.aspx). Layers corresponding to Brazilian biomes and administrative boundaries were obtained from Instituto Brasileiro de Geografia e Estatística (IBGE, https://www.ibge.gov.br). Distribution maps were constructed using QGis version 3.10.14-A Coruña (
MNRJ Museu Nacional do Rio de Janeiro, Rio de Janeiro, Brazil;
Family Simpulopsidae Schileyko,1999
Leiostracus vittatus (Spix, 1827) by subsequent designation.
Bulimus obliquus
Bulimulus obliquus
—
Bulimus jeffreysi
Drymaeus obliquus
—
Drymaeus obliquus var. monozona Ancey, (1901): 93.
Drymaeus obliquus var. poecilogramma —
Leiostracus obliquus
—
Leiostracus (Leiostracus) obliquus —
Lectotype. Brazil • 1 shell;
“Bahia” (
“Bul testâ subpyramudali-ovatá, umbilicatá, crassiusculá, ad basin oblique product, anfractibus septen ad octo, lævibus, aperturá obliquá, columella labroque latè dilatates; pallidè rosacea, anfracta ultimo fascia castaneâ unicâ cingulato.” (
Brazil • 9 specimens preserved in ethanol 70%; Minas Gerais, Mantena; Coltro leg.;
Brazil • 1 shell; Minas Gerais; Vanatta, E. G. leg.;
Shell
(Figs
Average, range, and ratios of measurements (mm) from shells of Leiostracus obliquus for material housed in Museums. ad: shell apertural diameter; ah: shell apertural height; bwh: body whorl height; masd, major diameter of the shell; misd: minor diameter; psl: parietal space length; pwd: penultimate whorl major diameter; pwh: penultimate whorl height; sh: spire height; tsh: shell height). Shell perimeter (mm) (sp: shell perimeter; ssa: shell surface area; spp: spire perimeter; spsa: spire surface area; bwp: body whorl perimeter; bwsa: body whorl surface area; ap: aperture perimeter; asa: aperture surface area).
Measurement | Leiostracus obliquus from mantena n = 9 | Lectotype |
|
|
---|---|---|---|---|
tsh | 30.81-21.87 (±2.75) 24.52 | 22.7 | 22.51 | 23.23 |
bwh | 19.08-14.08 (±1.57) 15.26 | 12.58 | 14.43 | 13.24 |
sh | 11-73-7.71 (±1.3) 9.39 | 7.96 | 8.39 | 10.03 |
masd | 14.06-10.02 (±1.2) 11.48 | 12.05 | 9.88 | 10.25 |
misd | 10.24-8.94 (±0.52) 9.52 | 7.99 | 9.01 | 9.08 |
ah | 12.84-9.06 (±1.12) 10.06 | 9.45 | 9.91 | 9.31 |
ad | 9.08-5.09 (±1.15) 6.98 | 6.97 | 7.04 | 7.48 |
psl | 7-19-4.88 (±0.93) 5.97 | 6.44 | 6.49 | 6.74 |
pwh | 4.07-2.99 (±0.39) 3.37 | 3.10 | 3.11 | 3.86 |
pwd | 7.88-6.67 (±0.39) 3.37 | 6.63 | 6.85 | 7.49 |
sp | 65.1-52.2 (±0.44) 56.9 | 47.99 | 54.87 | 56.68 |
ssa | 212.0-151.4 (±22.6) 170.3 | 127.99 | 164.11 | 168.11 |
spp | 34.6-17.5 (±4.9) 29.2 | 24.95 | 27.04 | 30.29 |
spsa | 68.2-32.9 (±11) 45.4 | 34.43 | 37.96 | 48.12 |
bwp | 48.8-42 (±2.56) 44.1 | 37.5 | 43.06 | 42.36 |
bwsa | 168.2-109.5 (±18.9) 127.8 | 93.21 | 125.13 | 119.86 |
ap | 33.5-25.6 (±2.6) 28.8 | 26.36 | 27.72 | 27 |
asa | 66.2-25 (±12.2) 44.6 | 47.94 | 49.46 | 50.54 |
Images of protoconch and radula of Leiostracus obliquus (Reeve, 1849) scanning electron micrograph (SEM) A protoconch showing sculpture B detail of sculpture of the second whorl showing the two sculpture types, first whorl with regular striation and second whorl with oblique irregular striations in the upper part, in the middle and lower part with punctuation aspects C general view of the first tree whorls D general view of the protoconch and first two whorls E general view of the radula showing the teeth arrangement F detail of rachidian teeth and first lateral teeth G detail of eighth and ninth lateral teeth (arrow) showing the transition from lateral to marginal teeth H detail of lateral region. Scale bars: 75 μm (A); 250 μm (B); 100 μm (C, G); 1 µm (D); 200 μm (E); 40 μm (F); 50 μm (H).
Radula
(Fig.
Pallial system
(Fig.
Leiostracus obliquus (Reeve, 1849), anatomy A ventral view of the pallialsystem dissected out, showing the inner face of ventral view B detail of albumen gland showing internal lobs C ventral view of the reproductivesystem without ovotestis D dorsal view of the reproductivesystem. Abbreviations: ag, albumen gland; bc, bursa copulatrix; ca, carrefour; fl, flagellum; ga, genital atrium; hd, hermaphrodite duct; k, kidney; mb, mantle border; pe, pericardium; pr, prostate; pur, pulmonary roof; pv, pulmonary vein; re, rectum; spo, spermoviduct; sur, secondary ureter; vd, vas deferens; ur, ureter. Scale bar: 2 mm (A–D).
Genital system
(Fig.
Brazil. Bahia, Espírito Santo, Minas Gerais, Rio de Janeiro, and São Paulo states (Suppl. material
The shell characters of the specimens from
Comparison between Leiostracus obliquus and other species of Leiostracus that occur in Brazil. Abbreviations: H: total shell height; D: Major diameter of the shell; h: aperture height. The marking * indicates that the internal anatomy from a rehydrated specimen.
Species | Type locality | Number of whorls | Shell measurements | Radula | Reproductivesystem | Distribution |
---|---|---|---|---|---|---|
L. obliquus (Reeve, 1849) | Brazil, Bahia | 7-8 | H: 23 mm D: ~12.7 mm h: ~11.5 mm | Rachidian, symmetric, rectangular. Laterals: bicuspid. Marginals: tetracuspids. | Penis with penis sheath. Flagellum short, subcylindrical. Spermatheca reservoir claviform. | Brazil (Bahia, Espírito Santo, Minas Gerais, Rio de Janeiro, São Paulo). |
L. carnavalescus Simone & Salvador, 2016 | Brazil, Minas Gerais, Nanuque | 8 | H: ~25 mm D: 12.4 mm h: 9.2 mm | Rachidian: triangular; Lateral and marginals: asymmetrical similar to rachidian. | Penis with penis sheath. Flagellum absent. Spermatheca reservoir elliptical. | Brazil (Espírito Santo, Minas Gerais) |
L. cinnamomeolineatus (Moricandi, 1841) | "Habitat la Province de Bahia" | 6 2/3 | H: 21.5 mm D: 10.17 mm h: 8.58 mm | Rachidian: triangular; Laterals: ectocone reduced; Marginals: asymmetric, tricuspids. | Penis without sheath. Flagellum short, slender, U-shaped. Spermatheca reservoir globose. | Brazil (Bahia, Espírito Santo, Pernambuco). |
L. demerarensis (Pfeiffer, 1861) | Guyana, Demerara | 6.1 | H: 17.95–20.64 mm D: 10.66 mm | Rachidian: monocuspid Laterals: bicuspid Marginals: weakly tricuspid. | Penis with penis sheath. Spermatheca reservoir small, long duct.* | Guyana; Surinam; Brazil (Maranhão, Pará). |
L. faerie (Salvador & Cavallari, 2014) | Brazil, Espírito Santo, area in vicinity of Doce River | 6 | H: 14.6 mm D: 7.6 mm h: 5.8 mm | Without description | Without description | Kown only from type locality. |
L. fetidus Salvador & Cavallari, 2014 | Brazil, Bahia, Canavieira | 6 | H: 21.2 mm D: 10.5 mm h: 9.4 mm | Without description | Without description | Kown only from type locality. |
Variation on color pattern in Leiostracus obliquus (Reeve, 1849). A painting from the original description of L. obliquus in
On the other hand, L obliquus differs from L. cinnamomeolineatus in the morphology of the radula: in L. obliquus the rachidian tooth is nearly round, while in L. cinnamomeolineatus it is triangular (Table
In the present work, we redescribe the species Leiostracus obliquus (Reeve, 1849), providing new information on shell micro sculpture, radular morphology, and anatomy of the soft parts. The striking similarities in shell morphology and color pattern between Leiostracus obliquus and L. carnavalescus, evidenced by comparison with the type material, the species original descriptions, and other specimens from malacological collections leads us to think that these are the same species. Notwithstanding, DNA analyses comparing L. obliquus specimens with L. carnavalescus type material are necessary to clarify these assumptions.
The material from Zoölogisch Museum of Amsterdam was donated by Dorhn and probably was used by him to describe varieties of L. obliquus (Dohrn, 1883) which are identical to the three color patterns described for L. carnavalescus. Moreover, the specimens herein identified as L. obliquus cannot be differentiated from L. carnavalescus through the anatomy of the soft parts and radular morphology.
Leiostracus obliquus was described from a single dry shell and since its description, records of this species are scant and outdated. L. obliquus is mentioned in the most recent Brazilian species lists by
Comparisons between the shells of the varieties from L. obliquus and L. carnavalescus showed remarkable similarities in morphology and color pattern. Concerning the “specimen #1” (
Color polymorphism refers to the occurrence of multiple discrete color phenotypes within the populations of the same species (
As we mentioned above, the species now ascribed to Leiostracus were allocated to different genera of Orthalicoidea in the past (
Leiostracus obliquus differs from all other species of the genus due to its conical-oval shell, with a brown line on the base of the body whorl, a reflected apertural lip and by presenting a fine brown sutural line, which is an uncommon trait among species of this genus. This species can be distinct from L. cinnamomeolineatus due to the presence of spiral brown lines and the absence of a sutural line in the shell. Shell dimension is also different, with the shell of L. obliquus being slightly larger (~ 23 mm, with 7–8 whorls) compared to the shell of L. cinnamomeolineatus (~ 21.5 mm, with 6 2/3 whorls).
Our findings suggest that Leiostracus obliquus may be endemic to Brazil, where it is primarily found in Atlantic Forest areas. In the original description,
The authors would like to thank the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) for granting a fellowship to MIPFM. We are grateful to Jonathan Ablett, Natural History Museum of United Kingdom and Macy Hafner, Academy of Natural Science of Philadelphia for providing images of the specimens of L. obliquus, Pedro Loureiro, and Laboratório de Microscopia Eletrônica da Universidade Federal de Juiz de Fora - Brazil, for their support during MEV imaging.
We deeply appreciate all comments provided by the editor, Edmund Gittenberger, and the two anonymous reviewers to whom we are thankful. Their recommendations significantly enhanced the quality of this paper.
No conflict of interest was declared.
No ethical statement was reported.
This research was financed by the Fundação de Apoio à Pesquisa do Estado de Minas Gerais – (FAPEMIG), APQ-01441-21.
SD conceptualized and supervised the work; SD and MIPFM organized data and wrote the original draft; XMCO, SD and MIPFM revised and edited drafts, XMCO edited the figures and tables.
Maria Isabel P. F. Macedo https://orcid.org/0000-0001-9272-0432
Ximena M. C. Ovando https://orcid.org/0000-0003-4541-3151
Sthefane D’ávila https://orcid.org/0000-0001-6494-309X
All of the data that support the findings of this study are available in the main text or Supplementary Information.
Localities of occurrences of Leiostracus obliquus in Brazil
Data type: table (docx. file)