Simrothula paraensis, Gomes, Suzete Rodrigues, Picanço, Juliane Bentes, Veitenheimer, Inga L., Mendes & Thomé, José Willibaldo, 2006

Gomes, Suzete Rodrigues, Picanço, Juliane Bentes, Veitenheimer, Inga L., Mendes & Thomé, José Willibaldo, 2006, A new species of Simrothula (Gastropoda, Soleolifera, Veronicellidae) from Northern Brazil, Zootaxa 1329, pp. 59-68 : 61-66

Simrothula paraensis sp. nov.

Type material: Holotype: MPEG 2731, R.N. Bittencourt coll., 22 Oct.1985. Paratypes (from the type-locality): MPEG 2732, 1 specimen, M.F. Torres, 19 June 1985; MPEG 2733, 1 specimen, J. Dias, 30 Oct 1985; MPEG 2734, 1 specimen, F. Remos & J. Dias, 3 Nov 1985; MPEG 2735, 4 specimens, R.N. Bittencourt, 22 Oct 1985; MPEG 2736, 1 specimen, R.N. Bittencourt, 29 June 1985; BMNH 20060092, 2 specimens, R.N. Bittencourt, 21 Oct 1985; MCP 8819, 6 specimens, R.N. Bittencourt, 30 Oct 1985.

Type-locality: BRAZIL, Pará: Serra Norte da Serra de Carajás, approximately 55 Km south of Belém, between the Itacaiuna and Parauapebas rivers (Lat.: 554’–633’S; Long.: 4953’–5034’W) ( Fig. 19 ).

Etymology: The name of the species refers to the State of Pará where the specimens were collected.

Diagnosis: S. paraensis differs from the other Simrothula species by having an expansion like a small lamina on one side of the glans of the penis, near the distal extremity of the penis base, a longer bursa copulatrix duct and a stronger developed accessory gland.

External characteristics: All specimens examined are small and narrow ( Figs. 1–3 ). The sole is remarkably narrower than the hyponotum. The notum (dorsal region) has a brownish to yellowish coloration. The coloration in the brownish specimens is almost homogenous while the yellowish specimens have some irregularly distributed darker points and striations. In some specimens there is a dorsal faint pale median stripe, which is mainly visible in the specimens with a lighter coloration. The hyponotum (ventral region) and the sole are light beige. In some specimens there are some black spots near the perinotum (border between the dorsal and ventral region).

Measurements (mm): Holotype: total length: 35.00, total width: 12.50, sole width: 3.37, hyponotum width: 5.87. Average (17 specimens of type-series): total length: 35.59, total width: 10.73, sole width: 3.05, hyponotum width: 4.97

Digestive system: The digestive system is formed by a buccal bulb, followed by an esophagus, a gastric crop, a stomach, an intestine, a rectum and by a posterior anus. There are two salivary glands with big and well-defined acini connected to the buccal bulb, where the jaw and the radula are located. The buccal bulb is followed by an esophagus that leads into a well developed gastric crop (more than three times the width of the esophagus). The gastric crop leads into a stomach that is wider than long. Two strongly developed lobes of the digestive gland open into the stomach, one anterior and one posterior. Posterior to the stomach the anterior region of the intestine forms a loop (the anterior intestinal loop). The anterior lobe of the digestive gland totally covers the anterior intestinal loop. Subsequently the intestine continues back to the posterior region until near the female genital pore, where it penetrates the body wall. This is where the rectum begins. The latter continues to the end of the body where it opens via the anus, which is hidden under the sole and has an opercular membrane. There is no separate aperture for the nephridiopore, which is probably connected to the rectum within the body wall.

The jaw shows on average 21 conspicuous ribs that are somewhat separated from each other ( Fig. 4 ). The most central rib is a bit larger than the others. The ribs have wellmarked transverse grooves. The radula has 95–97 teeth per transverse row, which is represented by one central or rhachis tooth, flanked on both sides by lateral teeth ( Figs. 5–9 ). The dental formula is C/1+L47–48/2. The lateral teeth are gradually smaller towards the edges ( Figs. 8–9 ). All teeth have one unique cuspid which is lance-shaped and they are on a rhomboidal base. The central tooth is distinctly smaller than the laterals.

Pedal and pallial nerves, pedal aortic system: One pair of pallial and one of pedal nerves run both parallel and together to each other from the central nervous system towards the posterior of the body cavity. They are slightly separated at the posterior region. The pedal aortic artery runs between the pairs of pallial and pedal nerves. It arises from a bifurcation of the anterior aortic artery near the pericardium and runs between the nerves until they terminate at region posterior of the body.

Pedal gland: The pedal gland, located on the anterior extremity of the sole under the head, is relatively long and straight. The gland has two different areas: one external lighter and another one internal yellowish. The posterior extremity of the gland receives a very thin pedal gland artery and may be somewhat inclined.

Reproductive system: The penis ( Figs. 10–13 ) has a well-defined base and glans. The base is long and cylindrical (longer than the glans). The glans starts from a slight constriction of the base. It is strong curved in the proximal region, and it is tapered toward the end, where the vas deferens opens. On the curved side there is an expansion on one side, like a small lamina. The penis has a retractor muscle with a length similar to the penis length. The penial gland ( Fig. 10 ) has a conical papilla with about 15 tubules of uniform size. Near the base of the papilla, the tubules are enveloped by a muscular membrane.

The bursa copulatrix ( Figs. 10 , 14–16 ) has a long and coiled cylindrical duct, which has about three times the length of the bursa. The bursa is ovoid and has a prominent digitiform expansion in the basal region. The whole structure has a pear-shape appearance.

The canalis junctor ( Thomé 1975; Barker 2001) connects the proximal posterior vas deferens with the digitiform expansion of the bursa copulatrix ( Fig. 15 ). A well-developed accessory gland ( Thomé 1975; Silva & Thomé 1995) is found between the rectum and the oviduct, connected to the last one. The canalis junctor is adherent to the surface of the accessory gland.

Figures

FIGURE 19. Map showing the locality where Simrothula paraensis sp. nov. was collected.

FIGURE 1 – 3. Specimens of Simrothula paraensis sp. nov. 1. Dorsal view of an specimen with brownish notum (MCP 8819). 2. Dorsal view of an specimen with a yellowish notum (MPEG 2735). 3. Ventral view (MPEG 2735).

FIGURE 4 – 9. Jaw and radula of Simrothula paraensis sp. nov. (MPEG 2736). 4. Jaw (frontal view). 5. Medium part of the left half of the radula showing the central and lateral teeth. 6. Detail of the central region of the radula. 7. Lateral teeth near to the central teeth. 8. Lateral teeth gradually smaller towards the edges. 9. Lateral teeth near to the edge.

FIGURE 10 – 13. Reproductive system of Simrothula paraensis sp. nov. (BMNH 20060092). 10. Complete reproductive system. 11 – 13. Three different views of the penis from an adult specimen (BMNH 20060092).

FIGURE 14 – 16. Reproductive system of Simrothula paraensis sp. nov. (BMNH 20060092). 14 – 16. Arrangement of the genital organs around the female genital pore (MPEG 2735). ab, accessory gland; cb, bursa copulatrix; db, duct of the bursa copulatrix; dd, distal posterior vas deferens; df, anterior vas deferens; di, digitiform formation; dp, proximal posterior vas deferens; dt, course of the vas deferens in the integument; el, laminar expansion; fc, fertilization complex; fg, female genital pore; gb, albumen gland; gn, glans; gh, hermaphroditic gland; jd, canalis junctor; md, medium vas deferens; ol, spermoviduct; ov, oviduct; pl, penial gland papilla; pr, prostate; rp, penis retractor; sv, seminal vesicle; tp, penial gland tubules; vg, penis base.