PHALLOMEDUSIDAE

Golding, Rosemary E., Ponder, Winston F. & Byrne, Maria, 2007, Taxonomy and anatomy of Amphiboloidea (Gastropoda: Heterobranchia: Archaeopulmonata), Zootaxa 1476, pp. 1-50 : 19

Family PHALLOMEDUSIDAE fam. nov.

Diagnosis: Shell conical-globose, diameter to 20 mm, solid, brownish-red vertical zigzag patterning across teleoconch or restricted to spire; whorls rounded; spire moderately tall, conical; umbilicus intermediate width, lacking columellar fold; aperture with simple outer lip lacking sinus, thickened at base. Operculum entirely corneous, thick, elliptical, dark brown with eccentric paucispiral nucleus in lower left corner, hollow keel on interior surface around nucleus. Head grey in fresh and formalin-preserved specimens, with black pigmented stripe on central snout; eyes at central base of small triangular tentacles; foot with simple opercular lobe. Opposed ciliary tracts short, restricted to exhalant canal; hypobranchial gland at right anterior mantle cavity roof flat, pyriform, brown-flecked in fresh specimens. Radula with central tooth, inner and outer lateral teeth, approximately 25 marginal teeth on each side of radula; central tooth bearing five wide cusps, inner lateral teeth bicuspid, outer lateral teeth with three equal size cusps, marginal teeth unicuspid, elongate, broad. Central nervous system euthyneurous; cerebral and pleural ganglia separated by short commissures; subcerebral and parapedal commissures present; visceral loop relatively long, lacking accessory ganglion. Reproductive system syntremous diaulic; ovotestis intertwined with digestive gland. Seminal vesicle present as single diverticulum from upper hermaphrodite duct; seminal receptacles numerous diverticula from hermaphrodite duct above carrefour. Spermoviduct dividing below carrefour; vas deferens long, lined with prostatic glandular tissue, terminating at complex spiral penis; oviduct terminating at muscular vagina. Penis elaborate, large, with unciliated external sperm groove, bearing tentacle-like appendages at distal end. Egg mass narrow, cylindrical string deposited in coil on surface of substratum.

Remarks: Phallomedusidae fam. nov. contains a single genus with two species, one of which was previously included in the Amphibolidae based on shell and opercular characters. Anatomical investigation and the discovery of additional diversity within the Amphibolidae have revealed major differences between Amphibola solida Martens, 1878 and other known amphibolids, necessitating the creation of a new family. Phallomedusidae fam. nov. is clearly distinguished from the Amphibolidae by the lack of a sinus on the outer lip of the aperture and the zigzag pattern of the shell, a prominent hollow keel on the inner surface of the operculum, broad marginal radular teeth, syntremous diaulic reproductive system, muscular vagina, vas deferens lined with prostatic glandular tissue and spiral penis with external sperm groove and long appendages. The characters of the reproductive system, in particular, are very different from those of amphibolids.