Scolodonta carajaensis Salvador, Ferreira-Santos, Cavallari, Gallão & Bichuette, 2026, sp. nov.
Authors: Salvador, Rodrigo B., Ferreira-Santos, Laura, Cavallari, Daniel C., Gallão, Jonas E., Bichuette, Maria E.
Type: Taxonomic treatment
Published: 2026-08-03
Keywords: Biodiversity, Taxonomy, Animalia, Mollusca, Gastropoda, Stylommatophora, Scolodontidae, Scolodonta, Scolodonta carajaensis

<p><i>Scolodonta carajaensis</i> sp. nov.</p><p>Figs 2 E – F, 4 A – C</p><p><b>Type material.</b></p><p><i>Holotype</i> LES 0031619. <i>Paratypes</i> LES 0031618 (collected together with holotype) • CMRP 1300 (ex LES 0031640) (Parauapebas, cave N 3_0003; JE Gallão, TS Gallo, DF Torres & JEM Santos leg., 13. viii. 2022).</p><p><b>Type locality.</b></p><p>Brazil, Pará state, Canaã dos Carajás municipality, FLONA de Carajás, Serra Sul, cave S 11 D_0001 (GEM 00650) (JE Gallão, JS Gallo, FD Torres & VF Sperandei leg., 11. ii. 2022).</p><p><b>Diagnosis.</b></p><p>Spire elevated; body whorl short, with rounded profile (lacking a marked angulation); aperture D-shaped, rounded; peristome simple.</p><p><b>Description.</b></p><p>Shell small (~ 6 mm wide), discoid, with ~ 4 ¹ / 2 whorls; glossy and translucent, tan in colour. Shell smooth except for fine growth lines. Protoconch seemingly has 1 1 / 2 whorl, but transition to teleoconch is indistinct. Spire slightly elevated; spire whorls with a weakly convex profile. Suture well marked, slightly deep. Whorls increase regularly in both width and height. Body whorl profile rounded. Aperture D-shaped, rounded. Insertion of aperture on body whorl just 0.1–0.2 mm over the median region of whorl. Peristome simple, sharp. Umbilicus wide, deep. Shell measurements (holotype): 4 ¹ / 2 whorls, shell height = 3.0 mm, shell width = 6.0 mm.</p><p>Soft body, orange-red (Fig. 2 E, F); some parts (middle of the eyestalks, tip of lower tentacles, border of the foot, edge of the mantle) are slightly paler and less reddish. Head-foot, marked by longitudinal rows of minute and more darkly pigmented spots. Head-foot narrow, with very narrow “ tail ”; eyestalks proportionately long (around the same size as frontal end of head-foot). Mantle and soft parts are partially visible through the shell.</p><p><b>GenBank acc. nr.</b></p><p>PZ 576041 (COI), PZ 575549 (16 S) (LES 0031619); PZ 576042 (COI), PZ 575550 (16 S), PZ 575551 (ITS 2 + 28 S) (CMRP 1300).</p><p><b>Distribution.</b></p><p>Known from caves in the municipalities of Canaã dos Carajás (type locality) and Parauapebas, in Serra dos Carajás.</p><p><b>Habitat.</b></p><p>Found from the entrance to the aphotic zones of the caves. Live individuals were found in very humid microhabitats: under rock, in an area with plenty of organic matter and plant roots (in Canaã dos Carajás), and on unconsolidated substrate close to water drip (in Parauapebas).</p><p><b>Etymology.</b></p><p>The specific epithet alludes to the study area, Serra dos Carajás.</p><p><b>Remarks.</b></p><p><i>Scolodonta</i> is primarily identified by its glossy and often translucent shell (Hausdorf 2006), which is slightly sturdier-looking than those of other glossy-shelled scolodontids (e. g., <i>Happia</i> Bourguignat, 1890, <i>Systrophiella</i> Baker, 1925). The lack of shell sculpture (except for fine growth lines) and the weakly elevated spire are also diagnostic of the genus (Hausdorf 2006).</p><p>We are confident in assigning our specimens to a new species, even though two species of “ <i>Scolodonta</i> ” are already known from Pará state. Dohrn (1882) described both <i>Scolodonta nitidula</i> (Dohrn, 1882) and <i>Scolodonta amazonica</i> (Dohrn, 1882) (originally allocated to <i>Ammonoceras</i> Pfeiffer, 1855) from the margins of the Amazon River in Pará. While his descriptions are informative, the original study lacks illustrations. Neither species has been figured since, and the type material is likely lost (Dance 1966). Nevertheless, based on the descriptions and discussion in Dohrn (1882), his <i>S. nitidula</i> is likely synonymous with <i>Tamayoa decolorata</i> (see below), which has a smaller and more rounded shell, as well as a yellow head-foot. On the other hand, <i>S. amazonica</i> is described as having a punctiform and barely visible umbilicus (Dohrn 1882), which is immediately inconsistent with <i>Scolodonta carajaensis</i> sp. nov. Furthermore, <i>S. amazonica</i> has a reflexed peristome around the columella and an even rounder aperture in comparison to <i>S. nitidula</i> / <i>T. decolorata</i> (Dohrn 1882), which is again inconsistent with the new species.</p><p><i>Scolodonta carajaensis</i> sp. nov. can be readily distinguished from other Brazilian Scolodontidae. <i>Scolodonta bounobaena</i> (d’Orbigny, 1835) is similar in overall shell shape, but it is slightly smaller, with thicker walls; also, it has a stronger angulation in the median-apical region of the body whorl, and a lightly thickened peristome. <i>Scolodonta interrupta</i> (Suter, 1900) is similar in size but has a much more raised spire and a more circular aperture. Furthermore, the periodical interruptions seen in the shell of <i>S. interrupta</i> are more reminiscent of members of the family Streptaxidae, which could indicate an incorrect allocation (Salvador 2021). <i>Scolodonta spirorbis</i> (Deshayes, 1850) is much smaller, with a fragile discoid shell, and very likely does not belong in <i>Scolodonta</i> (Roosen et al., unpub. data).</p><p>The occurrence of this species in more than one cave across the two municipalities suggests that the species is more widespread on the surface across Serra dos Carajás. Such an established epigean population is supported by genetic evidence; there is a 100 % match of both COI and 16 S sequences of the holotype and paratype, one from each municipality, indicating interconnectivity and gene flow. Furthermore, no obvious troglomorphisms were observed; the translucent shell is very common in multiple members of this family (Roosen and Breure 2024 a, 2024 b; Roosen et al. 2025 a, 2025 b) and cannot be considered a troglomorphism per se.</p>