Diniatys dubia ( Schepman, 1913 )

Too, Chin Chin, Carlson, Clay, Hoff, Patty Jo & Malaquias, Manuel António E., 2014, Diversity and systematics of Haminoeidae gastropods (Heterobranchia: Cephalaspidea) in the tropical West Pacific Ocean: new data on the genera Aliculastrum, Atys, Diniatys and Liloa, Zootaxa 3794 (3), pp. 355-392 : 382

Diniatys dubia ( Schepman, 1913)

Haminea dubia Schepman, 1913: 474 , pl. 32, figs 8, 9.

Diniatys ? dubia — Carlson & Hoff 2003.

Haminoea sp. 2 — Gosliner et al. 2008: 27.

Type locality. Balabalagan Islands located between Borneo and Sulawesi ( Paternoster Islands ) .

Material examined. Mariana Islands, Guam, 2 spcs dissected, UF 299907, H = 6.1, 6.3 mm.

Animal ( Fig. 1I ): Body whitish-translucent, whitish dots abundant over the body, densely organized between eyes and around edge of cephalic shield; mantle with dark brownish network of lines and whitish blotches throughout; eyes visible.

Shell ( Figs 3C , 16A–C ): Maximum height 12 mm; whitish; fragile, thin, translucent, ovoid, narrower towards both ends, posterior part broader than anterior part, anterior end protruded, posterior end truncated; spire sunken, columella end semi-translucent, strongly calcified, folded outwardly, becoming thicker but not forming a tooth-like projection; spiral grooves at both ends only (anterior = 8–10, posterior = 5–6), inconspicuous axial lines present throughout shell.

Jaws: Present, crescent shape.

Radula ( Figs 16D, E ): Radular formula at mid-point 30–36 x 8–6.1.6–8; median tooth at anterior part of radula semi-circular and more pointed at posterior part; outer lateral teeth hook-shaped, grooves along both outer and inner margins, size increases outwardly but outermost tooth smallest.

Gizzard plates ( Figs 16F, G ): Three gizzard plates; widest in the middle, narrower towards both ends, 14–15 ridges, V-shaped, rachis conspicuous, top edge of ridges and rachis covered by tiny rods with pointed tips, both anterior and posterior sides of ridges smooth.

Male reproductive system ( Fig. 16H ): Total length 4 mm (H = 6.1 mm). Formed by three parts: prostate, seminal duct and penial region; prostate single-lobed, elongated, opaque-yellow; long and thin seminal duct connects prostate and penial region, translucent, slightly coils at both ends; penial region elongated, lightyellowish, about half of length of seminal duct.

Ecology. Sandy bottom where it feeds upon cyanobacterium Microcoleus , between 12–27 m deep ( Gosliner et al. 2008, present study).

Geographical distribution. the Philippines, Indonesia, Papua New Guinea, Guam, Hawaii ( Gosliner et al. 2008; present study).

Remarks. This species has been subjected to taxonomic confusion. Schepman (1913) named it Haminoea dubia based on features of the gizzard plates and outer lateral teeth. Carlson & Hoff (2003) placed it provisionally in the genus Diniatys and Gosliner et al. (2008) named this species Haminoea sp. 2 . Shells of this species displayed a strongly calcified callus at the end of the columella folding outwardly, which is distinct from the tooth-like projection at the end of columella in Diniatys dentifer . In addition, this species also shows differences in the gizzard plates and radula compared to Diniatys dentifer . The median tooth in D. dubia is semi-circular, whereas in D. dentifer it has a sharp triangular central cusp with smaller triangular cusps at both sides. Gizzard plates of this species display single rows of tiny rods along the top edge of ridges, whereas the latter possesses tiny rods on both top edge and anterior side of ridges. On the other hand, both species possess male reproductive systems with long and fine seminal duct and elongated narrow penial region. Preliminary molecular phylogenetic analyses ( Too 2011) further support the inclusion of this species in the genus Diniatys .

Figures

FIGURE 1. Live images. A. Aliculastrum cylindricum (Koumac, northern New Caledonia; H = 28 mm, MNHN, Paris), B. Aliculastrum debilis (Maui, Hawaii; ZMBN 81658; H = 9 mm), C. Aliculastrum parallelum (Guam; UF 374138; H = 19 mm), D. Atys multistriatus (Guam; UF 374136; H = 7 mm), E. Atys pittmani nov. sp. (Maui, Hawaii; ZMBN 81673; H = 10 mm), F. Atys semistriatus (Maui, Hawaii; ZMBN 81656; H = 6 mm), G. Atys ukulele nov. sp. (Maui, Hawaii; ZMBN 89710; H = 5.4 mm), H. Diniatys dentifer (Guam; UF 374130; H = 9 mm), I. Diniatys dubia (Guam; UF 299907; H = 12.7 mm), J. Liloa curta (Guam; UF 374131; H = 15 mm), K. Liloa porcellana (Maui, Hawaii; ZMBN 89712; H = 4.2 mm); L. Liloa porcellana (Maui, Hawaii; ZMBN 89712; H = 2.8 mm). Image A, courtesy of W. B. Rudman; Images B, E–G, K, L, courtesy of C. Pittman.

FIGURE 3. Shells. A. Atys ukulele nov. sp. (Maui, Hawaii; ZMBN 89711; H = 4.6 mm), B. Diniatys dentifer (the Philippines, MNHN, Paris (B17/ OT793); H = 3.5 mm), C. Diniatys dubia (Guam; UF 299907; H = 7.5 mm), D. Liloa curta (the Philippines; MNHN, Paris (S12/ OT575); H = 3.1 mm), E. Liloa porcellana (Guam; UF 299895; H = 6.7 mm), F. Liloa porcellana (Maui, Hawaii; ZMBN 89712; H = 4.2 mm), G. Liloa porcellana (Maui, Hawaii; ZMBN 89712; H = 2.8 mm). Scale bar: 1 mm.

FIGURE 16. Shell and anatomy of Diniatys dubia. A. Detail of anterior part of shell. B. Axial lines in the middle part of shell. C. Detail of posterior part of shell and sunken spire. D. Detail of median tooth at the anterior part of radula. E. Detail of outer lateral teeth at right side of radula. F. Top view of gizzard plate. G. Rods on ridges of gizzard plate. H. Male reproductive system. go, genital opening; pr, prostate; ps, penial sheath; sd, seminal duct. Scale bars: A, G = 20 µm; B, C = 200 µm; D = 2 µm; E = 10 µm; F = 100 µm; H = 1 mm. A–C, F-H: UF 299907, H= 6.1 mm; D, E: UF 299907, H = 6.3 mm.