Contributions to Zoology, 86 (1) – 2017Isabel T Hyman; Irantzu de la Iglesia Lamborena; Frank Köhler: Molecular phylogenetics and systematic revision of the south-eastern Australian Helicarionidae (Gastropoda, Stylommatophora)

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Mysticarion Iredale, 1941

Mysticarion Iredale, 1941: 7.

Type species: Mysticarion leucospira insuetus Iredale, 1941, by original designation; masculine


Diagnosis. Shell. Small to medium-sized, thin, pale golden to golden amber, glossy, globose with a low spire, whorls rounded. Protoconch with notched spiral grooves, teleoconch with very fine spiral grooves or smooth (Figs 14-15).


Fig. 14. Shells of Mysticarion. A-B. M. insuetus: A. Syntype of Mysticarion leucospira insuetus AM C113776 (size indicative; photographer: AM). B. M. insuetus AM C.517468. C. Paratype of Mysticarion obscurior sp. Nov. AM C.524914. D. M. porrectus (probable holotype of Helicarion porrectus Iredale, 1941 AM C.101136 (size indicative, photographer: AM). E-F. M. hyalinus: E. Syntype of Vitrina hyalina Pfeiffer, 1855 NHMUK 1983075 (photographer: NHMUK). F. Holotype of Fastosarion staffordarum Stanisic, 2010, QM MO62372 (size indicative, photographer: QM). Scale bar = 10 mm.


Fig. 15. Scanning electron micrographs showing shell microsculpture in Mysticarion. A-C. M. insuetus, QM MO49377: A. Protoconch. B. early teleoconch. C. mid-teleoconch. D-F. M. hyalinus, AM C.512424: D. Protoconch. E. early teleoconch. F. mid-teleoconch. Scale bars = 100 µm.

Animal. Pale cream with minimal markings. Mantle lobes usually small, not fused; shell lappets wide at base, rapidly tapering, triangular (Fig. 16).


Fig. 16. Live specimens of Mysticarion. A. M. insuetus, AM C.506269, Oxley Wild Rivers NP. B. M. obscurior, AM C.524913, Wambina NR. C. M. porrectus, AM C.5000935, Mt Tomah. D. M. porrectus, resting pose, AM C.517188, Dorrigo. E-F. M. hyalinus: E. AM C.512424, Cunningham’s Gap. F. AM C.512438, Bunya Mountains. Scale bars = approx. 5 mm.

Genitalia. Spermoviduct of 2-4 lobes, embedded in digestive gland. Talon and carrefour embedded in albumen gland. Spermoviduct not folded into foot but with 1-2 small folds in proximal half. Free oviduct with spherical capsular gland in distal portion; internal walls of capsular gland smooth, remainder of free oviduct with weak longitudinal pilasters (absent in one species). Bursa copulatrix moderately long, approximately half spermoviduct length; sac portion oval; inserted at junction of penis and free oviduct. Vagina absent. Penis tunica attached tightly by muscle fibres to middle of epiphallus; epiphallus enters penis through verge; epiphallic caecum absent; near flagellum, epi­phallus containing internal cryptae; epiphallic flagellum with axial filament present, containing spiraling rows of internal cryptae with a long slender tail. Spermatophore a soft-walled capsule with hard tail-pipe; relatively long, complex branching spines present in spiraling pattern along tail-pipe.

Remarks. Mysticarion was introduced for two globose semislugs, Vitrina leucospira Pfeiffer, 1857 and its nominal subspecies M. leucospira insuetus (Iredale, 1941). Vitrina leucospira has since been excluded from the genus based on an examination of the type material, which does not appear to be that of an Australian helicarionid; and the taxon insuetus has been elevated to a full species. Helicarion porrectus Iredale, 1941 and Vitrina hyalina Pfeiffer, 1855 were both subsequently included in Mysticarion by Hyman and Ponder (2010) and followed by Stanisic et al. (2010). This treatment is confirmed here by molecular phylogenetics.

This genus contains arboreal semislugs with a golden, globose shell with a relatively high whorl count and a pale body. The genital features unifying this group include a moderately long penis with a penial verge and longitudinal pilasters, a short epiphallus with an accessory flagellum containing internal cryptae but no epiphallic caecum, a moderately long bursa copulatrix, and the absence of a vagina. The spermatophore is spiraling with branched spines present on the base of the capsule and continuing on the tail-pipe.