Aglaja sp.

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 779-780

Aglaja sp.

Figs 100, 101

MATERIAL EXAMINED. — Fiji. BORDAU 1 : stn CP 1467, 18°12’S, 178°36’W, 417-427 m, 3 lv (Figs 100A, B, D); stn CP 1503, 18°12’S, 178°35’W, 430 m, 1 lv (Figs 100C, E) .

DISTRIBUTION. — Collected in Fiji (Fig. 101), in 427-430 m.

DESCRIPTION. — External morphology. The body is oval, 24 mm long (largest specimen examined). The cephalic shield is variable in shape and size, probably with the state of preservation. In some specimens it is rounded and small, comprising about 1/3 of the body length (Fig. 100A), whereas in others it is more elongate, comprising about 1/2 of the body length. The 2 Hancock’s organs are composed of about 14 simple folds. There are about 9 small, rounded labial glands surrounding the mouth area, and a large sensory process at each side of the mouth opening (Fig. 100B). The parapodia are narrow. The posterior shield is rounded posteriorly, with 2 lobes and a flagellum on the left side near the mid-line of the body. The gill is simple, with 12 lamellae. The colour of the preserved animals is uniformly dirty white.

FIG. 100. External morphology and anatomy of Aglaja sp. A , dorsal view of a preserved specimen from Fiji, BORDAU 1 stn CP 1467, scale bar = 1 mm; B, same specimen, detail of

TQ the mouth area, scale bar = 1mm; C, digestive system of a specimen from Fiji, BORDAU 1 stn CP 1503, scale bar = 1 mm; D, shell of a specimen from Fiji, BORDAU 1 stn CP 1467, scale bar = 1 mm; E, reproductive system of a specimen from Fiji, BORDAU 1 stn CP 1503, scale bar = 1 mm. Abbreviations: ag, albumen gland; am, ampulla; bc, bursa copulatrix; cs, cephalic shield; dg, digestive gland; es, oesophagus; esg,

QI external seminal groove; f, flagellum; gl, gill; ho, Hancock’s organ; lg, labial gland; mg, mucous gland; p, penis; pa, parapodium; ph, pharynx; pn,

FT penial sac; pr, prostate; ps, posterior shield; rm, retractor muscle; sg, salivary gland; sp, sensorial process; sr, seminal receptacle.

EH

Shell morphology. The shell is internal, well calcified, narrow and curved near the inner whorl. It is at the posterior end of the body. Sculpture of faint growth lines (Fig. 100D).

Anatomy. The pharynx is large and muscular, and connects posteriorly with the wide oesophagus and the small salivary glands (Fig. 100C). Four strong retractor muscles attach anteriorly to the pharynx, which is devoid of radula or jaws. The oesophagus opens into a large digestive gland.

The reproductive system is monoaulic (Fig. 100E). The ampulla is long and convoluted. It connects to the long and curved mucous gland and the seminal receptacle. The seminal receptacle is small and pyriform, and enters the distal end of the mucous gland, which opens in the common atrium. From the common atrium a long duct connects with the rounded bursa copulatrix. From the gonopore an open seminal groove runs anteriorly to the protrusible cephalic penis and the prostate. The prostate is long and wide. The penis is large and curved near the tip, with a retractor muscle attached.

REMARKS. — Because the external colouration of the living animals is unknown, I prefer to leave this species unnamed. Aglaja sp. is placed in the genus Aglaja because of the presence of the following combination of characters: cephalic shield rounded, posterior shield with 2 lobes and a flagellum, head with a single pair of sensory processes, dorsal and ventral labial glands present, gill simple, buccal mass large and muscular, reproductive system monaulic, with the seminal receptacle proximal to the genital atrium, mucous gland with a single lobe, hermaphrodite duct with a branch connecting to the mucous gland, and penis unarmed, simple. All these characteristics were used by Gosliner (1980) to define the genus Aglaja .