Fastosarion Iredale, 1933

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 : 46-47

Fastosarion Iredale, 1933

Fastosarion Iredale, 1933: 37 . Type species Vitrina superba Cox, 1871 (OD).

Vercularion Iredale, 1933: 38 . Type species Helicarion bullaceus Odhner, 1917 (OD).

Description. External morphology: Shell reduced, 3 whorls, glossy, spire and apex flattened. 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 very large, rounded, fused at base, uniform in colour. Mantle lobes large to very large, left and median lobes fused to form single large lobe over head. Sole of foot and caudal apparatus as for family; caudal foss vertical slit in tail.

Mantle cavity: As for family. Mantle with visible minor blood vessels; pigmentation absent.

Digestive system: Oesophageal crop present.

Genital system: As for family. Carrefour embedded in albumen gland. Free oviduct of medium length; capsular gland present; irregular transverse internal sculpture present. Bursa copulatrix inserted on vagina, short, less than half spermoviduct length; duct of bursa copulatrix wide, distinguishable from bursa copulatrix, internally smooth. Vagina internally with longitudinal pilasters. Epiphallus enters penis through simple pore; penis internally covered in longitudinal ridges; longitudinal penis pilasters present; diverticulum on penis absent. Penial sheath enclosing only penis; penis retractor muscle attached to side of epiphallic caecum. Epiphallus simple internally. Epiphallic retractor caecum moderate in size, positioned in middle of epiphallus. Flagellum present; flagellum and distal part of epiphallus without internal cryptae and externally smooth and slender. Spermatophore not present in dissected specimens.

Radula: Relatively long and narrow. Central tooth with small ectocones; mesocone lanceolate, shorter than tooth base. Lateral and marginal tooth fields distinguishable. Lateral teeth with endocones absent; ectocone equal in size to those on central tooth; mesocone shorter than tooth base. Marginal teeth with endocones absent; ectocones shorter and narrower than mesocone, not subdivided into extra teeth.

Remarks. Fastosarion and Vercularion were both originally described as monotypic subgenera of Helicarion by Iredale (1933) but were later raised to genera ( Iredale 1937c). Fastosarion remained monotypic, including only Fastosarion superba ; however, Vercularion was expanded to include Helicarion brazieri Cox, 1873 , H. strangei Pfeiffer, 1850 , H. freycineti , Vitrina robustus Gould, 1846 , V. virens Pfeiffer, 1849 and V. aquila Cox, 1868 ( Iredale 1937c, 1941). The two genera were synonymised by R. C. Kershaw in Smith (1992). Stanisic (1993a) suggested this broad group, which includes a number of tropical and subtropical species, needs vigorous testing. However, he cited a communication from R. C. Kershaw indicating that there was a close relationship at least between F. superba and F. bullaceus .

Fastosarion superba was redescribed by Scott (1995), who also described two new species ( F. aquavitae Scott, 1995 and F. helenkingae Scott, 1995 ), bringing the total number of species in this genus to ten. Scott (1995) pointed out that Fastosarion could be distinguished from Helicarion by the presence of a distinct vagina and an epiphallic caecum, but appeared to be more similar to Thularion and Eungarion .

Three of the species assigned to Fastosarion by Smith (1992) were included in the current study: Fastosarion superba , F. freycineti and F. virens . All three species have shells of about three whorls; however, F. superba , the largest species, has much larger mantle laps and lobes with a higher degree of fusion. Each species had a similar reproductive system with a long vagina, fairly short epiphallic caecum and a long, slender flagellum. The penial complex was very similar in F. freycineti and F.virens . In both species the interior of the penis was covered with pustules, pilasters were absent and a small penial verge was present; in addition, both species had a short penial sheath covering only the bottom half of the penis. Fastosarion superba differed in the penis interior having fine V-shaped grooves and no penial verge, and the penial sheath covered the whole penis. The radula was only examined in F. superba and F. freycineti , but the radulae of these species differed in the number of marginal teeth and the length of the central and lateral tooth mesocones.

It appears that F. freycineti and F. virens are more closely related to each other than either are to F. superba . This was reflected in the phylogenetic analysis ( Figure 4 ), which showed Fastosarion to be diphyletic, indicating that F. freycineti and F. virens should be removed from Fastosarion . In order to determine the correct generic placement of these species, a specimen of Fastosarion bullaceus , the type species of Vercularion , was dissected (AM C441602; Dowah Creek, northeastern Queensland). This specimen shares with F. superba the presence of fine V-shaped grooves in the penis interior, a single penial pilaster and the absence of a penial verge. In addition, the two species both exhibit a penial retractor muscle attached to the middle of the epiphallus. The two species differ in the size of the penial sheath, which covers the entire penis in F. superba and only the base of the penis in F. bullaceus . However, the overall similarities of the reproductive system indicate that these two species should be united in Fastosarion and a new genus, Stanisicarion , is introduced below for F. freycineti and F.virens .

The other species included in Fastosarion by Smith (1992) cannot be confirmed in their generic placement without further study. Based on the original descriptions, there is some evidence to suggest that F. bullaceus is a synonym of F. brazieri ( Cox 1873; Odhner 1917). Fastosarion aquavitae and F. helenkingae show similarities to Stanisicarion in the penis interior and the presence of an incomplete penial sheath ( Scott 1995); while the anatomical data are insufficient to confirm their generic placement, they can be tentatively included there pending more detailed studies.

Eungarion , Thularion and Parmacochlea all have more reduced shells than Fastosarion , showing generally lower whorl numbers, degeneration and loss of calcification at the base of the shell and flattening of the spire. Anatomically, Eungarion and Thularion can both be distinguished from Fastosarion by a longer epiphallic caecum and the attachment of the penial retractor muscle to the base of the caecum. Parmacochlea differs anatomically from Fastosarion in its lack of a distinct vagina, attachment of the penial retractor to the base of the epiphallic caecum and the presence of a long, coiled vas deferens. All five genera included in this section differ in the internal structure of the penis (fine ridges in Fastosarion , papillate pilasters in Thularion and Eungarion , pustules in Stanisicarion and tiny pustules with one strong longitudinal pilaster in Parmacochlea ).

Figures

FIGURE 4. Australian Helicarionidae. Majority-rule consensus tree of 13,839 trees, length 99. Where two or more species from a genus are included, the genera are shaded. Groups A and B are referred to in text.