Drymaeus magus (Wagner, 1827)

Rosa, Rafael M., Salvador, Rodrigo B. & Cavallari, Daniel C., 2025, Te disappearing act of the magician tree snail: anatomy, distribution, and phylogenetic relationships of Drymaeus magus (Gastropoda: Bulimulidae), a long-lost species hidden in plain sight, Zoological Journal of the Linnean Society 203 : -

Drymaeus magus (Wagner, 1827) ( Figs 2–10 )

Bulimus inflatus Spix in Spix and Wagner 1827: 6 (pl. 7, fig. 1) [non Bulimus inflatus Olivier, 1801 , nor Lamarck, 1822]; Rezende 1975: 149; Fechter 1983: 222; Cowie et al. 2004: 77 (table 1).

Bulimus magus Wagner in Spix and Wagner 1827: 6 (pl. 7, fig. 1); Rezende 1975: 149; Fechter 1983: 222; Cowie et al. 2004: 77 (table 1).

Drymaeus magus : Pilsbry 1898: 253 (pl. 51, figs 7, 8); Rezende 1975: 149; Oliveira et al. 1981: 347; Oliveira and Almeida 1999: 36, textfig.; Oliveira and Almeida 2000: 4; Salgado and Coelho 2003: 162; Simone 2006: 139 (fig. 461); Birckolz et al. 2016: 149 (table 1); Simone and Amaral 2018: 185; Rosa et al. 2022: 6 (table 1).

Drymaeus (Mormus) magus : Morretes 1949: 150; Oliveira et al. 1981: 347.

Drymaeus (Drymaeus) magus : Breure 1979: 111; Breure and Eskens 1981: 95 (table 3).

Types

Te syntypes of the species consist of two shells. One syntype (ZSM 20020093; Fig. 3A ) perfectly matches the figure from the original description of this species ( Spix and Wagner 1827: pl. 7, fig. 1). Terefore, that specimen is here designated as the lectotype of Bulimus magus Wagner, 1827 . Te second syntype (ZSM 20240467) belongs to Drymaeus papyraceus (Mawe, 1823) .

Type locality

‘ Brasilien’ [ Brazil], designated herein according to the original label of the lectotype. Te localities reported by Spix and Wagner (1827) are considered erroneous (see Discussion below) .

Suggested vernacular name

Magician tree snail (or magician treesnail), which represents a translation of its Latin epithet. In Portuguese, the translated vernacular name would be ‘caracol-mago’.

Diagnosis

Shell small to medium-sized (height = 15–25 mm), broad, spire approximately one-third of shell height; colour beige to light brown, with large dark brown sinuous axial patches, occasionally crossed or interrupted by up to three blurred spiral bands; apex, peristome, and umbilicus ofen reddish brown to pinkish red; colour of periumbilical region occasionally distinct from the remainder of the shell and bordered by a continuous dark brown spiral line; umbilicus very narrow. Head dark grey, transitioning sharply at foot margin to pale grey/beige; tentacles coloured similar to head at their base, transitioning gradually to reddish brown distally, with a yellow tip. Albumen gland distinctly very large; bursa copulatrix duct narrow distally; penis small.

Redescription

Shell: Shell presenting one of two possible morphotypes ( Fig. 3 ). Adult shell either medium-sized ( Fig. 3A–F ; height = 22–25 mm) or small ( Fig. 3G–J ; height = 15–17 mm) for the genus, with six convex whorls and typical bulimoid outline; width approximately two-thirds of shell height; spire conical, height approximately one-third of shell height; spire angle ~55°. Ground colour beige to light brown, with large dark brown sinuous axial patches ( Fig. 3A–D, G–I ), which are either mostly continuous ( Fig. 3A–D ) or crossed or interrupted by up to three blurred spiral bands ( Fig. 3G–I ); apex, peristome, and region surrounding umbilicus from cream ( Fig. 3A ) to reddish brown to pinkish red ( Fig. 3F, J ), with the pinkish red either contiguous to remaining shell areas ( Fig. 3F ) or bordered and separated from the remainder of the shell by a continuous dark brown spiral line of variable width ( Fig. 3H–J ). Protoconch ( Fig. 3K ) with approximately two whorls; sculpture consisting of intercrossed axial and spiral lines of similar strength and width, forming a delicate reticulate patern; transition noticeable as a sudden change in sculpture. Teleoconch sculptured by axial growth lines, fine sinuous spiral striae ( Fig. 3B–D ), and ofen by coarse axial striae ( Fig. 3G, H ) with variable intensity; whorl profile convex; suture shallow but well marked. Aperture ( Fig. 3A–C, G ) large, oval, prosocline, height approximately half of shell height, width approximately three-quarters of shell width; peristome lighter coloured from cream to white, slightly reflected, more strongly so at the columellar region, forming a thin fold that partly covers the umbilicus ( Fig. 3B ), ofen separated from remainder of shell by a reddish axial band ( Fig. 3C ). Umbilicus very narrow ( Fig. 3F, J ).

Head-foot ( Figs 3I, J , 4A–G, I–K, N , 5A, B ): Typical in shape; head dark grey, uniform colour, transitioning sharply at foot margin; foot pale grey to beige, uniform; tentacles coloured similar to head at their base, transitioning gradually to reddish brown distally, and yellow at the tip.

Mantle organs ( Fig. 5A, B , 6E ): Mantle edge thick, unpigmented. Pneumostome ( Fig. 5B : pn) protected by a right ventral flap. Dorsal fold roughly twice as large as ventral flap, ~1.5 times longer. Lung ( Fig. 6E : pu) twice as long as wide, length roughly half a whorl. Pulmonary vein ( Fig. 6A–D : cv) large, located dorsally on pallial cavity. Pulmonary vessels conspicuous along right side of pulmonary vein ( Fig. 6E ), bearing clusters of transverse, roughly perpendicular ramifications; vessels less conspicuous on lef side. Remaining lung areas nearly smooth, with sparse inconspicuous vessels.

Visceral mass ( Fig. 5 ): Approximately 3.5 whorls in length. Digestive gland ( Fig. 7A–F : dg) bilobed; anterior lobe (da) flattened, posterior to pallial cavity, continuous to kidney; posterior lobe (dg) with ~2.5 whorls. Stomach encased by digestive gland, located ~1.5 whorls from visceral mass apex. Digestive tract surrounding anterior lobe of digestive gland. Gonad ( Fig. 9A, D–G : go) multi-lobed, encased between posterior lobe of digestive gland and columella ( Fig. 5 ).

Circulatory and excretory systems ( Fig. 6 ): Pericardium twice as long as wide, located ventrally and adjacent to posterior end of pallial cavity. Auricle ( Fig. 6A–D : au) located anteriorly, contiguous to the pulmonary vein ( Fig. 6A–E : cv), approximately twice as large as the ventricle ( Fig. 6A–D : ve). Kidney ( Fig. 6A–D : ki) simple, solid, roughly triangular, dorsoventrally flattened, approximately twice as large as pericardium, width approximately two-thirds of length. Nephropore ( Fig. 6F : ne) small, slit-like, located near transition from auricle to pulmonary vein. Ventricle ( Fig. 6A–D : ve) roughly triangular, contiguous to anterior aorta ( Fig. 6A–D : aa).

Digestive system ( Figs 7 , 8 ): Oral tube wide, muscular. Jaw ( Fig. 7A–I : jw) typical, consisting of a triangular middle plate and 16 imbricated lateral plates of similar width; plate length up to approximately six times width, gradually decreasing distally; colour yellowish brown, translucent. Buccal mass ( Fig. 7A–F, H, I : bm) stubby, roughly rounded, narrower anteriorly, with two ventrolateral expansions congruent with odontophore cartilages ( Fig. 7H, I : oc). Dorsal surface of oral cavity bearing a conspicuous pair of dorsal folds ( Fig. 7J : df). Odontophore cartilages ( Fig. 7H, I : oc) flatened, roughly triangular, each approximately twice as long as wide, fused ventro-anteriorly along approximately one-fifh of ventromedial margin. Radular sac short, slightly protruding posteriorly beyond odontophore cartilages, with contiguous nucleus ( Fig. 7H, I : rn).

Radula ( Fig.8 ) covering odontophore, with multiple rows containing a distinct rachidian tooth and 63–72 pairs of lateral teeth ( Fig. 8A–C ); teeth closely spaced, with a roughly rectangular base. Rachidian tooth ( Fig. 8D, E ) reduced, approximately half as wide and approximately three-quarters as long as lateral teeth, flatened, roughly triangular, tricuspidate; central cusp five times longer and four times wider than basal cusps, with blunt tip; basal cusps symmetrical, much smaller, triangular, with sharp tip. Lateral teeth ( Fig. 8D–H ) markedly distinct from rachidian, twice as wide and 1.25 times longer, asymmetrical, slightly arched laterally towards the radular margin, tricuspidate; base roughly rectangular, becoming slightly narrower and longer in teeth closer to the radular margin; proportions of cusps varying gradually towards the radular margin; inner basal cusp triangular, with a sharp tip, approximately half as long and wide as remaining cusps initially ( Fig. 8D ), becoming similar in length/width and shape to outer basal cusp ( Fig. 8G ) and more detached from central cusp towards the radular margin ( Fig. 8H ); central cusp roughly rectangular, ~1.5–2 times wider and longer than remaining cusps, with a rounded blunt tip; outer basal cusp triangular with a sharp tip, approximately half as long and nearly as wide as central cusp initially, eventually becoming bifid ( Fig. 8J, L ) or even trifid ( Fig. 8J ) near the 30th lateral teeth and onwards, with sharper tips; occasional atypical bicuspidate lateral teeth can be observed in the same position in all rows ( Fig. 8G ). Marginal teeth overall smaller than lateral teeth (approximately three-quarters as wide and long), with a proportionally narrower and longer base, tricuspidate ( Fig. 8K ); cusps proportionally shorter and blunter than that of adjacent lateral teeth ( Fig. 8I, K ); inner basal cusp triangular, with a sharp tip, approximately three-quarters as long and wide as remaining cusps; central cusp triangular, with a sharp tip, approximately one-quarter longer and wider than remaining cusps; outer lateral cusp bifid, approximately three-quarters as long and one-quarter wider than central cusp.

Salivary ducts ( Fig. 7A–F, H, I : sd) running dorsally along both sides of anterior oesophagus ( Fig. 7A–F, H, I : es), inserting into buccal mass near transition to oesophagus. Oesophagus ( Fig. 7A–F, H, I : es) approximately four times longer than buccal mass, with numerous dorsal folds. Stomach ( Fig. 7C–F : st) curved, encased by digestive gland, located ~1.5 whorls from visceral mass apex; gastric walls thin, smooth. Duct to digestive gland ( Fig. 7K : dd) branched, located at transition to intestine. Intestine ( Fig. 7A–F : in) long, smooth, with a sigmoid loop across the anterior region of the digestive gland. Rectum ( Figs 6E , 7A–F, L : rt) and anus ( Fig. 7A–F, L : an) located on the right posterior side of pneumostome. Anus ( Fig. 7A–F, L : an) sessile, slit-like, located inside pneumostome, inner surface with seven longitudinal simple folds ( Fig. 7L : an).

Reproductive system ( Fig. 9 ): Gonad position described above (visceral mass), composed of four lobes ( Fig. 9A, D–G : go). Hermaphroditic duct ( Fig. 9A, D–G : hd) narrow and thoroughly entangled, width relatively uniform, insertion on lef side of seminal receptacle. Seminal receptacle ( Fig. 9E : sr) small, sac-like. Fertilization complex simple, located at anterior end of seminal receptacle, completely immersed in albumen gland, insertion on posterior end of spermoviduct. Albumen gland ( Fig. 9A, D–G : ag) solid, elliptical, coiled, half a whorl long, four times larger than gonad; albumen gland duct subterminal, connected to distal end of spermoviduct; albumen chamber ( Fig. 9A, D–G : ac) length approximately one-sixth of spermoviduct length, volume approximately one-fifh of spermoviduct volume. Spermoviduct approximately one and a quarter whorls long, width inconstant along its length, surface irregular, intensely folded. Prostate ( Fig. 9A, D–G : pt) surface approximately one-third of spermoviduct surface, volume approximately one-quarter of spermoviduct volume. Uterus ( Fig. 9A, D–G : ut) volume approximately three-quarters of spermoviduct volume, external wall thick. Free oviduct ( Fig. 9A, D–G : fo) length ~1/20th of spermoviduct length. Vagina ( Fig. 9A, B, D–G : vg) length ~1/10th of spermoviduct length, inner surface with five longitudinal folds ( Fig. 9B : vg). Bursa copulatrix + duct ( Fig. 9A, D–G : bc, bd) as long as spermoviduct; bursa copulatrix duct as wide as spermoviduct proximally, twice as wide at mid-section, gradually much narrower distally ( Fig. 9A, D–G : bd); bursa copulatrix globose, laterally compressed, encased between pericardium and adjacent intestinal loop ( Fig. 9A, D–G : bc). Penis ( Fig. 9A, B, D–G : pe) length approximately half of spermoviduct length; penis muscle ( Fig. 9F : pm) very short (length ~1/20th of penis length), with terminal insertion; epiphallus ( Fig. 9A, D–G : eh) distinguishable from remaining penis through more irregular inner surface, length ~1/10th of penis length; inner penial surface without subchambers, posterior region bearing five narrow longitudinal folds, middle region smooth, anterior region bearing five narrow longitudinal folds ( Fig. 9B : pe); penis sheath ( Fig. 9A, D–G : ps) covering approximately the anterior quarter of the penis. Genital pore ( Fig. 9A, D–G : fp) round, simple.

Central nervous system ( Fig. 10 ): Pair of cerebral ganglia ( Fig. 10 : ce) located dorsally above oesophagus near transition from buccal mass; widely fused, cerebral commissure externally indistinguishable; nerves originating from anterolateral region of cerebral ganglia. Cerebral and pedal ganglia connected by parallel connectives surrounding oesophagus. Pair of pedal ganglia ( Fig. 10 : pp) located ventrally, more posterior than cerebral ganglia, fused as a single mass, slightly larger than cerebral ganglia.

Distribution

WidespreadinsoutheasternBrazil, withrecordsfromthestatesof Minas Gerais, São Paulo, Rio de Janeiro and Paraná ( Fig.2 ). In our review, we identified 49 occurrence records for Drymaeus magus : 11 from the investigated collections (3 from CMRP and 8 from MZSP), 36 from iNaturalist (Supporting Information File S1), and 2 from previous studies ( Oliveira et al. 1981). Records with uncertain identification or imprecise locality data, including the lectotype, were excluded. Most records are from São Paulo (35) and southern Minas Gerais (13). Tree potentially non-native records from the states of Rondônia (northern Brazil; iNaturalist obs. 108923731) and Mato Grosso do Sul (midwestern Brazil; iNaturalist obs. 120650892 and 120650890) were also found (see Discussion below). Additionally, a few published records from the state of Santa Catarina (e.g. Agudo-Padrón 2008; 2009, 2014, 2018, 2022) lack photographic evidence or voucher specimens and are therefore excluded from consideration.

Habitat and ecology

Dwells on tree trunks and leaves, mostly in seasonal semideciduous forests of the inland Atlantic Forest and Cerrado. Also recorded in anthropogenic habitats, including urban areas and coffee crops ( Rezende 1967). Nocturnal and more active during the rainy season, like most land snails ( Salvador and Tomotani 2024) and consistent with previous observations of Drymaeus ( Rezende 1975, Breure 1979).

Material examined

BRZIL. No specific data: ZSM 20020093 , one shell, lectotype. Minas Gerais: Arceburgo, Sítio Areias de Minas , 9 June 2023 , MZSP 164980 , one specimen. São Paulo: Pedregulhos, Parque Estadual das Furnas do Bom Jesus , 20°15 ′ 22.7 ″ S, 47°27 ′ 36.4 ″ W, 13 April 2024 , CMRP 1211 , three specimens; Ribeirão Preto, University of São Paulo campus, 21°09 ′ 56.6 ″ S, 47°51 ′ 49.1 ″ W, 12 January 2023 , CMRP 1049 , one specimen; 24 January 2023 , CMRP 1056 , one specimen; 11 October 2023 , CMRP 1118 , two specimens; Cava do Bosque , 21°10 ′ 23.9 ″ S, 47°47 ′ 58.8 ″ W, 1 January 1981 , MZSP 083293 , two shells; 1 April 1980 , MZSP 132081 , two shells; Caconde, forested area surrounding the Caconde hydroelectric power plant reservoir, 21°36 ′ 11.6 ″ S, 46°37 ′ 29.0 ″ W, 28 January 2023 , CMRP 1059 , one specimen; 7 March 2023 , CMRP 1087 , one specimen; 8 April 2023 , CMRP 1090 , one specimen; 13 January 2024 , CMRP 1169 , two shells; Serra Negra , 22°37 ′ 08 ″ S, 46°42 ′ 15 ″ W, 9 September 2023 , MZSP 166927 , one specimen; Porto Feliz , 3 January 1936 , MZSP 016772 , nine shells; Praia Grande , 1 January 1994 , MZSP 083926 , two shells .

Figures

Figure 2. Distribution records of Drymaeus magus. A, larger-scale map showing all known records in Brazil.B, close-up on the core distribution area (black square from A), taken to represent the natural occurrence of the species.

Figure 3. Collection specimens of Drymaeus magus showcasing shell morphology. A, Lectotype ZSM 20020093, apertural view. B–F, CMRP 1118, apertural, lateral, dorsal, apical, and umbilical views. G, MZSP 164980, apertural view.H, MZSP 166927, dorsal view. I, J, CMRP 1059, dorsal and umbilical views. K, CMRP 1118, protoconch detail.

Figure 4. Live specimens of Drymaeus magus from several localities, taken during field observations (A–I) and from iNaturalist (J–M). A–F, Ribeirão Preto, SP (by Vitor H. Piva). G, H, Ribeirão Preto, SP (by Rafael M. Rosa). I, Caconde, SP (by Vitor H. Piva). J, Pedralva, MG (iNaturalist obs. 70791456; by Taynara Marinho). K, Jundiaí, SP (iNaturalist obs. 206292248; by phk). L, Campinas, SP (iNaturalist obs. 38296526; by Arthur Gomes). M, Cabreúva, SP (iNaturalist obs. 40538695; by Rafael L. Rosa). N, Pedralva, MG (iNaturalist obs. 70791456; by Taynara Marinho).

Figure 5. External and internal anatomy of Drymaeus magus (CMRP 1049). A, external surface, lateral lef view. B, external surface, lateral right view. C, internal organ systems inside the organism, lateral lef view. D, internal organ systems, lateral lef view. E, internal organ systems inside the organism, dorsal view. F, internal organ systems, dorsal view. G, internal organ systems inside the organism, ventral view. H, internal organ systems, ventral view.

Figure 6. Mantle organs, circulatory and excretory systems of Drymaeus magus (CMRP 1049). A, circulatory and excretory organs inside the organism, lateral lef view. B, circulatory and excretory organs, lateral lef view.C, circulatory and excretory organs, dorsal view. D, circulatory and excretory organs, ventral view. E, mantle organs, ventral view of the mantle cavity roof.F, two-dimensional X-ray slice of the visceral mass showcasing the nephrostome. G, plane of section of the slice depicted in F.

Figure 7. Digestive system of Drymaeus magus (CMRP 1049). A, digestive organs inside the organism, lateral lef view. B, digestive organs, lateral lef view.C, digestive organs, lateral lef view, digestive gland rendered transparent to showcase the intestinal loops. D, digestive organs, ventral view. E, digestive organs, dorsal view.F, digestive organs, dorsal view, digestive gland rendered transparent to showcase the intestinal loops.G, head, anterior view, showcasing the mouth and jaw.H, anterior region of the digestive system, dorsal view, buccal mass rendered transparent to showcase the odontophore cartilages and radula.I, anterior region of the digestive system, lateral lef view, buccal mass rendered transparent to showcase the odontophore cartilages and radula.J, two-dimensional (2D) X-ray slice of the buccal mass showcasing its dorsal folds. K, 2D X-ray slice of the visceral mass showcasing the digestive gland ducts. L, 2D X-ray slice of the anus showcasing its inner longitudinal folds. M, plane of section of the slice depicted in K. N, plane of section of the slice depicted in L.O, plane of section of the slice depicted in L.

Figure 8. Radula of Drymaeus magus (CMRP 1049) under scanning electron microscopy (×55–×2700 magnification).A, wide-range view.B, detail of the central region. C, same, higher magnification.D, same, higher magnification, rachidian teeth (smaller) at the centre (longitudinally) and first three to four lateral teeth on both sides. E, same, higher magnification, rachidian tooth (smaller) at the centre and first lateral teeth on both sides. F, detail of the lef lateral region. G, same, higher magnification, atypical bicuspidate teeth at the centre (longitudinally).H, same, detail of lateral teeth.I, detail of the marginal region, wider view. J, marginal region, detail of the multicuspidate lateral teeth. K, same, detail of the marginal teeth. L, detail of the right region of radula, folded, teeth rows in lateral view.

Figure 9. Reproductive system of Drymaeus magus (CMRP 1049). A, reproductive organs inside the organism, lateral lef view. B, twodimensional X-ray slice of the anterior region of the reproductive system showcasing transversal sections of the vagina and penis. C, plane of section of the slice depicted in B. D, reproductive organs, lateral lef view. E, reproductive organs, lateral lef view, albumen gland rendered transparent to showcase the seminal receptacle. F, reproductive organs, dorsal view. G, reproductive organs, ventral view.

Figure 10. Circumoesophageal nerve ring of Drymaeus magus (CMRP 1049). A, nerve ring surrounding the oesophagus inside the organism, lateral lef view.B, nerve ring, lateral lef view.C, nerve ring, ventral view. D, nerve ring, detail of the pedal ganglia.