Mysticarion Iredale, 1941

Hyman, Isabel T. & Ponder, Winston F., 2010, A morphological phylogenetic analysis and generic revision of Australian Helicarionidae (Gastropoda: Pulmonata: Stylommatophora), and an assessment of the relationships of the family 2462, Zootaxa 2462 (1), pp. 1-148 : 30-36

Mysticarion Iredale, 1941

Mysticarion Iredale, 1941: 7 . Type species Mysticarion leucospira insuetus Iredale, 1941 (OD).

Description. External morphology: Shell reduced, 3.3–4.0 whorls, glossy, spire and apex flattened or slightly raised. Protoconch sculptured with incised spiral grooves; teleoconch with microscopic spiral grooves. Whorl profile rounded above and below evenly convex periphery. Internal walls of early whorls complete; umbilicus closed. Mantle laps wide at base, moderately short to moderately long, not fused, uniform in colour. Mantle lobes of medium size, left and median lobes fused [ Mysticarion hyalina ( Pfeiffer, 1855) ] or unfused ( M. porrectus ). Caudal apparatus as for family; caudal foss vertical or diamond-shaped slit in tail.

Mantle cavity: As for family. Mantle with visible minor blood vessels; pigmentation, if present, of white spots.

Digestive system: Oesophageal crop extremely small.

Genital system: Carrefour and talon both embedded in albumen gland. Free oviduct medium to long; capsular gland present; internal longitudinal pilasters absent ( M. porrectus ) or one pilaster present ( M. hyalina ). Bursa copulatrix inserted on vagina, moderately short, about half spermoviduct length; duct of bursa copulatrix wide, distinguishable from bursa copulatrix, internally with longitudinal pilasters. Vagina very short. Epiphallus enters penis through short verge; penis internally flat ( M. hyalina ) or covered in longitudinal ridges ( M. porrectus ), longitudinal penis pilasters present, diverticulum on penis absent. Penial sheath enclosing only penis; penis retractor muscle attached to epiphallus. Epiphallus internally with longitudinal pilasters. Epiphallic retractor caecum absent. Flagellum present; flagellum and distal part of epiphallus with internal cryptae forming external projections. Spermatophore not present in dissected specimens.

Radula: Relatively long and narrow. Central tooth with small ectocones; mesocone lanceolate, similar in length to tooth base ( M. hyalina ) or longer than tooth base ( M. porrectus ). Lateral and marginal tooth fields distinguishable. Lateral teeth with endocones smaller than central tooth ectocones; ectocone equal in size to those on central tooth; mesocones similar in length to tooth base. Marginal teeth with endocones absent; ectocones approximately same length and breadth as mesocone, subdivided into extra teeth.

Remarks. Mysticarion was introduced for M. leucospira insuetus and Vitrina leucospira Pfeiffer, 1857 because the shell is more globose than in other Australian semislugs ( Iredale 1941). Previous studies have included only these taxa in Mysticarion ( Burch 1976; Iredale 1941; Smith 1992; Smith et al. 2002; synonymised in the latter two studies).

The type species of Mysticarion , M. leucospira insuetus , was not included in this study because there was no wet material available for examination. Stanisic et al. (in preparation) describe this species as differing from M. porrectus in its slightly smaller shell and preference for drier habitats. One of the syntypes of M. insuetus (AM C113776) is figured for comparison ( Figures 7E , 8E , 9E ).

Examination of the syntypes of Vitrina leucospira by J. Stanisic revealed that the species has atypical shell sculpture and does not correspond to any known eastern Australian species (J. Stanisic, pers. comm.) This species should probably be excluded from the Australian fauna and is unlikely to be a member of Mysticarion .

We include Helicarion porrectus Iredale, 1941 in Mysticarion on the basis of its globose shell, the presence of a penial verge and longitudinal penial pilasters and the presence of a more slender and less tightly coiled flagellum with fewer projections, indicating a difference in spermatophore shape. Vitrina hyalina Pfeiffer, 1855 (incertae sedis in Smith 1992; Smith et al. 2002), was originally described and figured as globose ( Pfeiffer 1855; Reeve 1862), but was for many years confused with a species with a reduced and flattened shell belonging to Peloparion ( Cox 1868; Iredale 1937c; Tryon 1885). It is included here in Mysticarion based on an examination of the holotype and matching additional material. Both species of Mysticarion examined herein have a larger number of marginal radular teeth than members of Helicarion , Parmavitrina , Peloparion and Brevisentis .

Figures

FIGURE 7. Shells, dorsal view. A. Helicarion cuvieri, AM C443929. B. Helicarion cuvieri, BMNH 197780 (S of Vitrina verrauxii). C. Helicarion mastersi, AM C101139 (H). D. Helicarion mastersi, AM C101138 (PRH of H. mastersi callidus). E. Mysticarion insuetus, AM C113776 (S). F. Mysticarion porrectus, AM C101136 (PRH). G. Mysticarion hyalina, BMNH 1983075 (H). H. Parmavitrina planilabris, AM C103630. I. Peloparion helenae, AM C101142 (H). J. Brevisentis jacksoniensis, BMNH not registered (S). K. Brevisentis jacksoniensis, AM C101143 (H of B. exclusus). L. Fastosarion superba, BMNH not registered (POS). Scale bars 3 mm (G, I–K), 5 mm (A–F, H), 10 mm (L). Photographs by M. Allan (D, I), H. Barlow (A, C, H), D. Beechey (E–F, K), W. Ponder (B, G, J, L). Abbreviations: H, holotype; POS, possible syntype; PRH, probable holotype; S, syntype.

FIGURE 8. Shells, lateral view. A. Helicarion cuvieri, AM C443929. B. Helicarion cuvieri, BMNH 197780 (S of Vitrina verrauxii). C. Helicarion mastersi, AM C101139 (H). D. Helicarion mastersi, AM C101138 (PRH of H. mastersi callidus). E. Mysticarion insuetus, AM C113776 (S). F. Mysticarion porrectus, AM C101136 (PRH). G. Mysticarion hyalina, BMNH 1983075 (H). H. Parmavitrina planilabris, AM C103630. I. Peloparion helenae, AM C101142 (H). J. Brevisentis jacksoniensis, BMNH not registered (S). K. Brevisentis jacksoniensis, AM C101143 (H of B. exclusus). L. Fastosarion superba, BMNH not registered (POS). Scale bars 3 mm (E–G, I–K), 5 mm (A–D, H), 10 mm (L). Photographs by H. Barlow (A, C–D, G–H, L), D. Beechey (E, J), W. Ponder (B, F, I, K). Abbreviations: H, holotype; POS, possible syntype; PRH, probable holotype; S, syntype.

FIGURE 9. Shells, ventral view. A. Helicarion cuvieri, AM C443929. B. Helicarion cuvieri, BMNH 197780 (S of Vitrina verrauxii). C. Helicarion mastersi, AM C101139 (H). D. Helicarion mastersi, AM C101138 (PRH of H. mastersi callidus). E. Mysticarion insuetus, AM C113776 (S). F. Mysticarion porrectus, AM C101136 (PRH). G. Mysticarion hyalina, BMNH 1983075 (H). H. Parmavitrina planilabris, AM C103630. I. Peloparion helenae, AM C101142 (H). J. Brevisentis jacksoniensis, BMNH not registered (S). K. Brevisentis jacksoniensis, AM C101143 (H of B. exclusus). L. Fastosarion superba, BMNH not registered (POS). Scale bars 3 mm (D–G, I–K), 5 mm (A–C, H), 10 mm (L). Photographs by H. Barlow (A, C–D, H–I), D. Beechey (F, K), W. Ponder (B, E, G, J, L). Abbreviations: H, holotype; POS, possible syntype; PRH, probable holotype; S, syntype.