Atys pittmani nov. sp.

Type locality. Black Rock, Maui Island, Hawaii.

Etymology. We name this species after Cory Pittman, a chief collaborator and provider of specimens from the Hawaiian Islands. This also intends to honour his brilliant and dedicated work on the taxonomy and diversity of heterobranch gastropods of Hawaii.

Material examined. Maui, Hawaii, 1 spc. dissected and sequenced, ZMBN 81673, H = 10 mm; Black Rock, Maui, Hawaii, 2 spcs studied (holotype and paratype), ZMBN 92894, H = 6 (paratype), 8 (holotype) mm; the Philippines, 1 spc. dissected, MNHN, Paris (S18/ OT756), H = 4.9 mm.

Animal (Fig. 1E): Body whitish-opaque, whitish pigmentation densely covering cephalic shield and parapodial lobes; white and red blotches on the mantle; eyes visible.

Barcode: GenBank Accession No KF735657 (ZMBN 81673).

Shell (Figs 2F, 10A, B): Maximum height 10 mm; whitish; fragile, thin, semi-translucent, ovo-cylindrical, elongated, anterior end protruded, posterior end truncated; spire sunken, outer lip elevated slightly above the apex, aperture narrow posteriorly and slightly broader anteriorly, strongly calcified callus at the end of columella but does not form tooth-like projection; spiral grooves at both ends (anterior = 14–18, posterior = 5–9), light axial lines present.

Jaws: Present, crescent shape.

Radula (Figs 10C–F): Radular formula at mid-point 27–32 x 7–4.1.4–7; median tooth rounded-triangular to bilobed, denticulation present along edge; outer lateral teeth hook-shaped, slender, size decreases outwardly. There is no differentiation between inner and outer lateral teeth.

Gizzard plates (Figs 10G, H): Three gizzard plates; long and narrow; 22–28 ridges, semi-circular, pseudorachis presents, ridges covered by single rows of tiny rods with pointed tips along top margin, both anterior and posterior sides of ridges smooth.

Male reproductive system (Fig. 10I): Total length 2 mm (H = 10 mm). Formed by three parts: prostate, seminal duct and penial region; prostate elongated-pyriform, single-lobed, opaque-yellow, broad posteriorly, narrower towards seminal duct; seminal duct shorter and narrower than prostate, creamy-white; penial region cylindrical-elongated, translucent.

Ecology. Mud flat or on algae Halimeda; up to 10 m deep.

Geographical distribution. the Philippines and Maui, Hawaii (present study).

Remarks. Shells of this species have spiral grooves at both ends interconnected with light axial lines throughout shell, a feature also found in Atys multistriatus (here studied), Atys dactylus and Atys jeffreysi, the latter two species from the Atlantic Ocean. Live animals of both Atys multistriatus and Atys pittmani are highly similar. Whereas in Atys multistriatus the white dots visible through the shell in the dorsal part of the mantle form compact clusters, in Atys pittmani those are separated and sparse apart intermingled with red dots. Also the reticulated pattern in the shell is conspicuous in Atys multistriatus whereas in Atys pitttmani is very light almost inconspicuous. Anatomically they possess distinct male reproductive systems; Atys pittmani has an elongated and distally broader prostate and shorter seminal duct. Additionally, we have evidence from preliminary molecular phylogenetic analyses that confirm the different identities of these two species (Too 2011).

Both specimens examined of Atys pittmani have identical gizzard plates and male reproductive systems, but the radula showed some variability; the specimen from Hawaii had rounded-triangular rachidian teeth whereas, the specimen from the Philippines has broader bilobed rachidian teeth. In both specimens the rachidian teeth were denticulate along the top edge.