Fastosarion paluma Stanisic, 2010

Figs. 6, 7I–J, 8F, 17

Fastosarion paluma Stanisic, 2010 in Stanisic et al., 2010: 308–309, 329.

Material examined

Types: Holotype: QM MO55707 ( Paluma Ra., 3km W Paluma, NEQ, 19°01’S, 146°11’E, in grass, March 1995, J. Leroi).

Paratypes: QM MO34956, QM MO47981, QM MO55704, QM MO55706,

QM MO55763, QM MO58087, QM MO 63984, QM MO78897, AMSC106771.

Non-type material: See table 1.

Diagnosis

External morphology: Shell (fig. 7I–J) medium-sized (11.9–13.7 mm), pale amber, transparent, 3.3–3.5 whorls, subglobose with a low spire. Body (fig. 8F) 20–25 mm long, speckled grey to brown, darker on end of tail and neck, sometimes with a red tail tip. Shell lappets and mantle lobes moderately small, lobes mottled dark grey, lappets with black spots and markings forming a discontinuous border, each lappet with a strong ridge. Tail slightly keeled at tip, keel paler, slime network moderately strong.

Genital anatomy: Genitalia (fig. 17) with medium length vagina, slightly swollen; bursa copulatrix moderately short, duct distinct, bursa spherical. Penis moderately long, slender, slightly swollen proximally, internally with one longitudinal pilaster and one oval pilaster proximally, internal wall sculptured with coarse diagonal lamellae arranged in a deep chevron pattern; 60–100% of penis contained in penial tunica. Penis approx. equal in length to epiphallus, slightly narrower in diameter; epiphallic caecum long, with a small terminal bulb; flagellum moderately short, bumpy, terminal portion sometimes fused.

Spermatophore simple (based on fragment only).

Remarks

This species was described from the Paluma Range in northeast Qld (fig. 6). In the current study, specimens from Hinchinbrook Island were genetically and anatomically similar to those from the Paluma Range. Only a single sequence from each locality was available and the genetic distance between them was 5.6% (COI), higher than the intraspecific variation seen in any other species (see table 2). There was slight variation present in the genital anatomy: one specimen from Paluma Range lacked the oval penial pilaster, while a separate specimen from Paluma Range lacked any fusion in the flagellum tip; however, since these differences do not correspond with the genetic differentiation observed, we currently treat the Hinchinbrook population as conspecific with F. paluma . Further studies incorporating a greater number of samples would be of benefit in confirming this placement.

Fastosarion paluma is allopatric with respect to its congeners. It can be distinguished from F. brazieri (found to the north) and F. helenkingae (found further south) by its smaller size. Specimens from Palm Island that were originally identified as F. paluma have herein been shown to belong to new species Fastosarion insularis, which can be distinguished by its smaller size and more reduced and flattened shell.