Phallomedusa austrina, Golding, Rosemary E., Ponder, Winston F. & Byrne, Maria, 2007

Golding, Rosemary E., Ponder, Winston F. & Byrne, Maria, 2007, Taxonomy and anatomy of Amphiboloidea (Gastropoda: Heterobranchia: Archaeopulmonata), Zootaxa 1476, pp. 1-50 : 21

Phallomedusa austrina sp. nov.

Holotype ( Fig. 2 J): Australia, Tasmania: near Stanley, Sawyer Bay, East Inlet, damp mudflats between high tide and midshore, 20 Apr 2004, W.F. Ponder (AMS C.446510).

Paratypes: Same data as holotype (AMS C.446509), 19 specimens.

Etymology: Austrina (Latin—southern), in reference to the distribution.

Description: Shell ( Fig. 2 J): Solid, opaque, spire relatively short, shell diameter to 20 mm, slight shoulder on rounded last whorl; suture deeply impressed. Surface with uneven raised axial striae. Outer apertural lip thickened at base near columella. Exterior brown with narrow reddish-brown zigzags present only on spire, last whorl pinkish-green with pale band, pattern less distinct on lower whorls, often discoloured. Interior of aperture pink to purple.

Operculum: As for P. s o l i d a.

External morphology: As for P. s o l i d a.

Digestive system: As for P. solida .

Radula ( Figs. 11 C, D): As for P. s o l i d a.

Central nervous system: As for P. s o l i d a, but presence of subcerebral and parapedal commissures not confirmed.

Reproductive system ( Fig. 15 C): As for P. s o l i d a with following differences: Penis short, spiral base with only one or two spiral convolutions of sperm groove and associated flanges; lacking terminal shield. Tentaclelike appendages on distal penis much longer, thicker and more numerous than P. s o l i d a. Muscular vagina shorter with expanded upper oviduct rounded, lacking protruding bulges.

Distribution and habitat ( Fig. 1 ): Known only from East Inlet, Sawyer Bay, Stanley, north-western Tasmania, found sympatrically with P. s o l i d a, but occupying a lower portion of the shore. Phallomedusa austrina sp. nov. probably has a larger distribution, but the extent is unknown.

Remarks: Phallomedusa austrina sp. nov. is readily distinguished from P. s o l i d a by the enlarged lower whorl and reduced zigzag patterning of the shell and by the longer penial elaborations. Specimens of P. austrina sp. nov. have probably been historically misidentified as S. fragilis , as the distinctive patterning typical of Phallomedusa gen. nov. is often inconspicuous or obscured, and the structure of the shell bears a superficial resemblance to members of the genus Salinator . It can be readily distinguished from S. fragilis , which occurs in north Tasmania, but not at this locality, by the lack of sinus, purple interior of aperture, keeled operculum and distinct reproductive system. Quoy & Gaimard’s (1832) figures of varieties of Ampullacera fragili s do not depict this species.

Figures

FIGURE 1. Distributions of amphiboloidean species determined from the present study and previous reports. Species in bold are examined in this paper.

FIGURE 2. Shell morphology of species in Amphibolidae, Phallomedusidae fam. nov. and Maningrididae fam. nov .. A. Amphibola crenata (Martyn, 1786), (AMS C. 446522). B – D. Salinator fragilis (Lamarck, 1822), B. Lectotype (MHN 1094 / 1), C. Albany, Western Australia (AMS C. 446486), D. Cambridge, Tasmania (AMS C. 442291). E. Salinator tecta sp. nov .. Holotype, Narrabeen Lakes, Sydney (AMS C. 446774). F. Salinator rhamphidia sp. nov .. Holotype, Botany Bay, Sydney (AMS C. 446516). G. Salinator rosacea sp. nov .. Holotype, Elizabeth River, Darwin (AMS C. 446519). H, I. Phallomedusa solida (Martens, 1878), H. Holotype (ZMB 22207), I. Lake Illawarra, New South Wales (AMS C. 442239). J. Phallomedusa austrina sp. nov .. Holotype, Stanley, Tasmania (AMS C. 446510). K. Lactiforis tropicalis sp. nov .. Holotype, Broome, Western Australia (AMS C. 446775). L. Lactiforis takii (Kuroda, 1928). Ariake Sea, Japan (AMS C. 446490). M. Naranjia cf. swatowensis (Yen, 1939). Tsim Bei Tsui, Hong Kong (AMS C. 446511). N. Maningrida arnhemensis sp. nov .. Holotype, Maningrida, Northern Territory (AMS C. 446485). Scale bar = 2 mm.

FIGURE 11. SEM photographs of radulae of Phallomedusa gen. nov. and Maningrida gen. nov. species, showing halfradula and detail of central and lateral teeth. A, B. Phallomedusa solida (Martens, 1878). C, D. Phallomedusa austrina sp. nov .. E, F. Maningrida arnhemensis sp. nov .. A, C, E. Scale bar = 50 µm, B, D, F. Scale bar = 20 µm.

FIGURE 15. Distal reproductive structures of Phallomedusidae fam. nov .. Structures orientated with proximal region at top of figure and distal region including genital aperture at base of figure. Arrow indicates position of structure shown in detail. A. General configuration of distal reproductive structures of Phallomedusa solida (Martens, 1878), with spermoviduct entering at left of figure and preputium intact. Scale bar = 1 mm. B. Phallomedusa solida (Martens, 1878). Penis, dissected out of preputium with vas deferens and retractor muscle attached at proximal base, scale bar = 1 mm. C. Phallomedusa austrina sp. nov .. Penis, dissected out of preputium with vas deferens and retractor muscle attached at proximal base. Scale bar = 1 mm.