Bostryx rudisculptus (Parodiz, 1956)

(Figures 1 – 4)

Bulimulus (Scansicochlea) rudisculptus Parodiz, 1956: 78; Fernández, 1973: 85; Fernández and Castellanos, 1973: 279; Tablado and Mantinian, 2004: 371.

Bostryx rudisculptus Breure, 1979: 58; Cuezzo et al. 2013: 143.

Bostryx tortoranus Miquel, 1995: 123 [partim].

Type material

Holotype (MACN-In 380), Paratypes (MACN-In 380 – 1 (5)).

Type locality

‘ Baños de Villavil, provincia de Catamarca ’. Villavil is located in Catamarca province, Belén Department .

Material examined

Argentina, Prov. Catamarca, Dept. Belén: MACN-In 380, Baños de Villa Vil, 1933, Gómez M, leg.; MACN-In 380 – 1, Baños de Villa Vil, 1933, Gómez M, leg.; MLP 10171, Baños de Villa Vil, 1951, Carranza C; Dept. Santa María: IFML 16460, 10 km before La Hoyada, 26° 35 ′ 20 ″ S, 66° 21 ′ 40 ″ W, 2760 m, 25 November 2003, Cuezzo MG leg .

Shell. Dextral, fusiform, slender, thin, of 5½ whorls slightly convex (Figure 1A). Shell pale brown, with darker bands (Figure 1A). Protoconch with thick, axial, elevated costules, more marked near suture, parallel to each other (Figure 1B – E). Costules separated by regular narrow spaces. Spiral grooves, parallel, densely arranged, crossing them, thinner than costules (Figure 1B – E). Spire high conic, with whorls increasing regularly in diameter (Figure 1A). Body whorl tall in relation to total height of the shell, 70% of the total length (Figure 1A). Teleoconch with axial oblique ribs (Figure 1A). Suture simple, slightly deep (Figure 1A). Aperture elongated-ovate, tall, half of total shell length (Figure 1A). Parietal space narrow, smooth (Figure 1A). Peristome simple, not expanded (Figure 1A). Umbilicus narrow, partially overlapped by the peristome (Figure 1A).

Measurements. Type material measurements in Table 1.

Range of variability of the species: masd = 5.68 – 9.46; misd = 5.54 – 9.46; th = 12.89 – 20.63; bwh = 9.64 – 14.60; sh = 4.03 – 7.97; ah = 7.05 – 10.02; mad = 4.28 – 6.30.

External morphology. Lateral groove from genital orifice towards mantle collar, well marked. Foot elongate, basal sole homogeneous, not divided.

Digestive system. Jaw arched with 12 plaques, without sculpture. Central plaque rectangular divided into two minor plaques. Lateral plaques rectangular in shape, regular in size. Radula narrow and long. Central tooth small, triangular, tricuspid (Figure 2A). First lateral tooth bicuspid, similar in size and shape to central tooth (Figure 2A). Marginal teeth bicuspid or tricuspid (Figure 2B, C).

Pallial system (one specimen dissected). Kidney triangular, wider than long, slightly longer than pericardial cavity with inner longitudinal lamellae in contact between them. Pericardial cavity shorter than kidney. Primary ureter bordering kidney along its length. Secondary ureter parallel to rectum, opening at proximal portion of rectum. Distally the secondary ureter splitting into adrectal and abrectal branches. Interramus zone, rectangular, excavated. Rectum opening at mantle collar. Main pulmonary vein, parallel to rectum, with distal portion thinner than proximal portion. Minor veins well marked and thin.

Reproductive system (one specimen dissected). Ovotestis embedded in digestive gland. Albumen gland bean-shaped (Figure 3A, B). Hermaphroditic duct divided into three parts, central part convoluted seminal vesicle (Figure 3A, B). Proximal and distal hermaphroditic duct portion thin and elongated, and distal portion inserting into half portion of albumen gland (Figure 3A, B). Fertilization pouch – spermathecal complex, long and finger-shaped (Figure 3B). Spermoviduct oviducal portion long, transversely sacculated (Figure 3A). Distally, spermoviduct splitting into free oviduct and vas deferens (Figure 3A). Free oviduct shorter and thinner than vagina (Figure 3A). Bursa copulatrix sac rounded, small, with long duct, reaching distal portion of albumen gland, with broader distal portion (Figure 3A). Bursa copulatrix duct with two different inner wall sculptures, proximal longitudinal straight folds, distal zigzag folds. Vagina cylindrical, 1/3 of penis length (Figure 3A), inner wall with longitudinal parallel thick straight folds. Penial complex formed by penis, epiphallus and flagellum. Penial retractor muscle short, inserted terminally in flagellum (Figure 3C, D). Flagellum thin, short and cylindrical (Figure 3C, D) with inner folds diagonal with respect to central fold, longitudinal, thin fold extending towards epiphallus (Figure 3D). Epiphallus longer than flagellum, progressively increasing its width towards penis (Figure 3C, D). Inner epiphallus wall with straight, parallel folds in proximal portion, zigzag folds in distal portion (Figure 3D). Penis as long as epiphallus, divided into two regions by a thinner middle section (Figure 3C, D). Proximal penis swollen, internally wall sculpture consisting of thin straight folds followed by smooth area. Distal penis cylindrical with inner straight longitudinal folds area (Figure 3D). Inner penial papilla in proximal penis portion, elongated, triangular with terminal pore (Figure 3D). Penis sheath muscular, folded upon itself in its proximal portion, overlapping the distal portion of penis (Figure 3D). Retractor muscle, not divided, inserting on upper end of penis sheath (Figure 3A). Vas deferens thin, inserting at basal penis sheath (Figure 3A). Atrium short (Figure 3A), inner wall with zigzag folds.

Remarks

Bostryx rudisculptus was originally described in Bulimulus (Scansicochlea) Pilsbry, by Parodiz (1956), based on shell characters. However, strikingly in 1957 Parodiz did not list Bulimulus (Scansicochlea) rudisculptus as a species present in Argentina. Later Miquel (1995) relocated B. rudisculptus in Bostryx, the genus in which it is currently maintained (Cuezzo et al. 2013). The protoconch ’ s sculpture and the reproductive system organization confirm its classification in Bostryx .

Abbreviations: ah, apertural height; bwh, body whorl height; H, holotype; mad, apertural diameter; masd, major diameter of the shell; misd, Minor diameter; n, number of specimens; P, paratype; S, syntype; sh, spire height; th, total shell height;. Bostryx tortoranus (Doering, 1879) measurements according to Breure (2013). Measurements in mm.

Bostryx rudisculptus has a similar range to Bostryx catamarcanus (Parodiz 1956), a species which can be clearly differentiated by its shell shape and size. The shell of B. rudisculptus is smaller in height and diameter as well as aperture (in height and diameter); the teleoconch has ribs and darker bands. In B. catamarcanus in contrast, the teleoconch has costules and uniform coloration.

Bostryx rudisculptus is one of the smaller Argentinean species in the genus Bostryx, together with Bostryx cordillerae (Strobel), Bostryx costellatus (Hylton Scott) and Bostryx reedi (Parodiz) . Bostryx rudisculptus differs from B. cordillerae and B. reedi by its shell that has ribs and a taller aperture. Moreover it differs from B. reedi because of its slender shell, without parietal callus and narrower umbilicus. Bostryx rudisculptus differs from B. costellatus by its more slender shell, with narrower umbilicus, thinner walls and a teleoconch with densely arranged ribs, whereas in B. costellatus there are thicker and higher ribs, and these are more widely spaced.

Distribution and habitat

Bostryx rudisculptus is endemic to Catamarca province (26 – 27° S, 66 – 67°W), and known from Belén and Santa María Departments. It inhabits High Monte ecoregion (Figure 4) ranging in altitude between 1630 and 2760 m. It is found under rocks in contact with moist soil .