Leiostracus obliquus (Reeve, 1849)

Macedo, Maria Isabel P. F., Ovando, Ximena M. C. & D'avila, Sthefane, 2023, Redescription and geographical distribution of Leiostracus obliquus (Reeve, 1849) (Mollusca, Gastropoda, Simpulopsidae), ZooKeys 1167, pp. 223-240 : 223

publication ID	https://dx.doi.org/10.3897/zookeys.1167.98707
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scientific name	Leiostracus obliquus (Reeve, 1849)
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Leiostracus obliquus (Reeve, 1849) View in CoL

Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 6A-C View Figure 6

Bulimus obliquus Reeve (1849) [1848-1850]: 148; - Pfeiffer (1853): 342.

Bulimulus obliquus - Dohrn (1883): 352; - Martens (1885): 191.

Bulimus jeffreysi Pfeiffer (1852): 93; - Pfeiffer (1853): 342. - Pilsbry (1899) [1898-1899]: 93.

Drymaeus obliquus - Ancey (1901): 93; - Pilsbry (1899) [1898-1899]: 93, pl. 14 fig. 14.

Drymaeus obliquus var. monozona Ancey, (1901): 93.

Drymaeus obliquus var. poecilogramma - Ancey (1901): 93.

Leiostracus obliquus - Breure (1979): 127; - Salgado and Coelho (2003): 162; - Simone (2006): 122; - Breure and Ablett (2015): 37.

Leiostracus (Leiostracus) obliquus - Breure 1978: 227 [lectotype designation].

Type material.

Lectotype. Brazil • 1 shell; NHMUK 1975493. Syntype of B. jeffreysi : Brazil • 3 shells; NHMUK 20110083.

Type locality.

“Bahia” ( Reeve 1849).

Original diagnosis.

" 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. " ( Reeve 1849)

Material examined.

Brazil • 9 specimens preserved in ethanol 70%; Minas Gerais, Mantena; Coltro leg.; MZSP 43185 • 1 shell; Espírito Santo, Itapemirim; 22 Apr. 2001; Castro, G.A. leg.; CMMPO 8795 • 16 shells; Espírito Santo, Itapemirim; Mar. 2001; Castro, G.A. leg.; CMMPO 8797 .

Museum material.

Brazil • 1 shell; Minas Gerais; Vanatta, E. G. leg.; ANSP 79491 • 1 shell; Espírito Santo, South of Guarapari, Meaípe; Dec. 1992; Bodart, A. leg.; ANSP 426466 • 4 shells; Espírito Santo, near Posta de Souza , Doce River ; MCZ 57073 View Materials • 6 shells; Espírito Santo, Santa Teresa , Santa Lúcia, Trilha do Araponga; 22 Jan. 2002; MNRJ 9565 • 7 shells; Espírito Santo, Cachoeiro do Itapemirim , Cafundó, Mata do Panelao ; 20°48'16"S, 41°09'31"W; 22 Mar. 2002; MNRJ 9566 • 4 shells; Espírito Santo; Cachoeira do Itapemirim , Fazenda Cafundó, trilha 1; 20 Jan. 2001; MNRJ 9562 • 1 shell; Espírito Santo, Linhares; Oct. 1973; MNRJ 9568 • 1 shell; Espírito Santo, Linhares; 10 Nov. 1973; Salgado, N. C. leg.; MNRJ 33330 • 6 shells; Espírito Santo, Linhares; Sep. 1972; MNRJ 9569 • 6 shells; Espírito Santo, Linhares; Sep. 1972; MNRJ 9563 • 12 shells; Espírito Santo, Linhares; Sep. 1972; MNRJ 9564 • 1 shell; Espírito Santo, Linhares; Nov. 1972; MNRJ 9567 • 2 shells; Espírito Santo, Itaguaçú; Sep. 1971; MNRJ 9606 • 4 shells; Espírito Santo, Baixo Grande; Oct. 1971; Salgado, N. C. leg.; MNRJ 32846 • 6 shells; Espírito Santo, Baixo Guandú; MNRJ 9604 • 1 shell; Espírito Santo, Pedro Canário, Rio Itaunas , Faz. Rochysky; Jun. 1970; MNRJ 8332 • 2 shells; Rio de Janeiro ; Salgado, N. C. leg.; MNRJ 31149 GoogleMaps .

Redescription.

Shell (Figs 2A-D View Figure 2 , 3 View Figure 3 ). Shell perforate, pyramidally ovate, umbilicated, thick. Shell height from 21.87 to 30.81 mm (Table 1 View Table 1 ); seven or eight whorls slightly convex. Protoconch 1½ whorls, white to pale pink, with well-marked regular striation (Fig. 3A View Figure 3 ). Teleoconch sculptured with delicate spiral striae (Fig. 3C View Figure 3 ), with a single narrow dark-brown line in the last whorl, surface with regular and shallow striae. Spire high, ~ 3/5 of the shell length. Second whorl with two forms of sculpture, oblique irregular striations in the upper part, irregular striations in the middle part, and spiral lines, with punctuations in the lower part (Fig. 3B-D View Figure 3 ). The transition between protoconch and teleoconch well marked. Aperture broad, oblique, ovate to subovate. Outer lip and columella broadly reflected (Fig. 2A View Figure 2 ). Suture well-marked, simple, slightly oblique, with a thin purple-brown line (Fig. 2B View Figure 2 ). Body whorl, white to pale cream; wide pale-pink disrupted band all over the teleoconch (Fig. 2A-C View Figure 2 ). Peristome widely expanded in adult specimens (Fig. 2C View Figure 2 ). Body whorl ~ 2/5 of the shell length, rounded; umbilicus narrow, partially covered by the peristome; periumbilical area pale cream (Fig. 2D View Figure 2 ).

Radula (Fig. 3F-H View Figure 3 ). Approximately 75 teeth per row. Mean number of teeth per half row (except for central tooth) 37. Each radular row disposed linearly on the same level (Fig. 3E View Figure 3 ). Rachidian tooth small (~ 4/5 of the length of laterals), rectangular, symmetric, with round edges, without differentiated cusps (Fig. 3F View Figure 3 ); basal plate almost trapezoidal; cutting edge slightly round. Lateral teeth asymmetrical, bicuspid, basal plate wider, weakly arched towards the median region, and with cutting edge, ½ the size of the rachidian tooth (Fig. 3G View Figure 3 ). First lateral tooth with conspicuous inner cuspid; base wider than the apical part. The size of the lateral teeth decreases gradually towards the outer area. Basal-lateral cusp appears in the third or fourth teeth and becomes more distinct in the marginal teeth. Marginal teeth with four cuspids, mesocone well developed, with a bicuspid cutting edge, endocone relatively reduced, bicuspid or tricuspid (Fig. 3H View Figure 3 ).

Pallial system (Fig. 4A View Figure 4 ). Mantle border simple, thick. Rectum narrow, walls thick. Primary ureter along the rectal side of the kidney up to the top of the lung cavity. Secondary ureter, wide and slender, parallel along the entire left side of the rectum. Mantle cavity short, ~ 1/4 of the body whorl. Kidney elongated, narrowly triangular, thin, ~ 1/3 of the pallial cavity in length, with ~ 7 lobes, the anterior lobe at the level of the auricle slightly longer. Pericardial cavity on the left side of the kidney, at the columellar margin of the posterior end of the pallial cavity, near the same length as the kidney. Auricle elongate, ~ 1/3 of the triangular ventricle. Pulmonary vein visible in the mantle roof, almost as long as the pallial cavity, oblique in the anterior 1/2, converging to the pneumostome region along with the ureter and rectum. Slender vessels visible on both sides of the pulmonary vein, at the distal portion of the pallial system.

Genital system (Fig. 4B-D View Figure 4 ). Ovotestis with three or four branches of enlarged digitiform acini, each branch with more than 20 simple acini. Hermaphroditic duct tubular, very sinuous, thick, folds itself in an S-shape. Albumen gland small, slightly elongated (Fig. 4B, C View Figure 4 ). Spermoviduct, bursa copulatrix and penial complex with approximately the same length when distended. Bursa copulatrix elongated (~ 1/3 larger than spermoviduct), thin. Bursa sac slightly elongated terminally, lying on the concave face of the spermoviduct. Prostate long, with numerous tubular-acini, in the columellar surface of the spermoviduct. Penial complex long, club-shaped, phallus subcylindrical, penis with a sheath. Phallus-epiphallus transition unrecognizable externally. Insertion of the vas deferens subterminal. Flagellum present, subcylindrical, short, ~ 1/10 of penial complex length. Insertion of the bursa copulatrix and penial complex into the free oviduct at the same level. Genital atrium very short, ~ 1/10 of spermoviduct length. Spermatheca well-differentiated, sinuous, lying at the superior third of the albumen gland.

Distribution.

Brazil. Bahia, Espírito Santo, Minas Gerais, Rio de Janeiro, and São Paulo states (Suppl. material 1). Localities of occurrence are mainly in the Atlantic Forest biome (Fig. 5 View Figure 5 ).

Remarks.

The shell characters of the specimens from MZSP, identified here as L. obliquus matched with the original description made by Reeve (1849) and the lectotype designed by Breure (1978) (Fig. 6A, C View Figure 6 , Table 1 View Table 1 ). After comparing our specimens with the material from several malacological collections, we concluded that L. obliquus is very similar to Leiostracus carnavalescus Simone & Salvador, 2016. Both species are medium-sized (24.5 mm ± 2.7 in L. obliquus whereas in L. carnavalescus 24.4 mm ± 1.3) (Table 1 View Table 1 ), presenting conical-oval shells, with a typical brown line on the base of the body whorl (Fig. 6A View Figure 6 ), 7-8 whorls, and outer lip widely reflected. In the original description of L. carnavalescus , Simone and Salvador (2016) provided two images of a specimen from Mantena, whose shell characteristics match the original description of L. obliquus . We also observed notable similarities between Dorhn’s “varieties” and the three color patterns described for L. carnavalescus , all of them exhibiting a brown band on the base of the body whorl mentioned by Dohrn (1833) and Pilsbry (1899) for L. obliquus (Fig. 6B, D View Figure 6 ). The holotype of L. carnavalescus is identical to Dorhn’s "variety 2" (Fig. 6B View Figure 6 ; Dohrn 1833: fig. 11). The paratypes #1 and #2 (MZSP 106179 and M`ZSP 106178, respectively) of L. carnavalescus are similar to Dorhn’s "variety 4", presenting pinkish bands and fine lines of brown spots (Fig. 6B View Figure 6 ; Dohrn 1833 date: fig. 15). Dorhn’s "variety 3" (Fig. 6B View Figure 6 ; Dohrn 1833: fig. 13) is similar to "specimen #2" of L. carnavalescus from Sooretama (Fig. 6D View Figure 6 ), both present yellowish shells, with wide pinkish bands, a brown band at the base of the body whorl, and a thin brown sutural line. Lastly, Dorhn’s "variety 5" (Fig. 6B View Figure 6 ; Dohrn 1833: fig. 14) is similar to the paratype #3 (MZSP 106179) of L. carnavalescus . Both presents wide dark bands with a fine brown line of punctations. Dohrn (1883) did not specify where the material analyzed by him was deposited. Nonetheless, we found two lots donated by Dorhn and identified as L. obliquus from Brazil, housed in the Zoölogisch Museum of Amsterdam (ZMA 385620; ZMA 385621). We believe this material could be part of the specimens used by Dorhn to establish those color varieties of L. obliquus . The shell from ZMA 385620 is similar to Dorhn’s "variety 3", while the shells from ZMA 385621 are similar to Dorhn’s "variety 1" and "variety 2". The analysis of these specimens also confirmed the similarities between L. obliquus and L. carnavalescus . The radulae of both species are identical: the rachidian tooth is rectangular, symmetric, without differentiated cusps and the basal plate is almost trapezoidal; cutting edge slightly round; lateral teeth bicuspid and weakly arched towards the median region (Table 2 View Table 2 ). The anatomy of the reproductivesystem is also identical in both species (mainly the presence of the penis sheath and the morphology of the penis complex).

On the other hand, L Leiostracus 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 2 View Table 2 ). However, this variation may be the result of age and/or diet. Considering the anatomy of the reproductivesystem, both species can be differentiated by the shape of the flagellum, which is longer and slender in L. obliquus , and inverted U-shaped and less tapered flagellum in L. cinnamomeolineatus , as well as by the shape of the bursa copulatrix reservoir, which is claviform in L. obliquus and globose in L. cinnamomeolineatus (Table 2 View Table 2 ).