Vaughanites? superstes new species

Figures 2 S, 16G–H, 18C–I)

Type material. Holotype MNHN 24573, paratype MNHN 24574.

Type locality. Philippines, Bohol Sea, off Balicasag Island, 9º29.4’N, 123º44.4’E, 271– 318 m.

Material examined. Philippines, Bohol Sea, off Balicasag Island, 9º29’N, 123º44’E, 271–318 m, 1 lv (holotype MNHN 24573, sequenced as IM- 2007-35222); off Balicasag Island, 9° 30.1N, 123° 41.6E, 356-396 m, 1 dd; off Pamilacan Island, 9º27’N, 123º49’E, 273–356 m, 1 lv (paratype MNHN 24574); off Siquijor Island, 9º01’N, 123º26’E, 427 m, 3 dd.

PAPUA NEW GUINEA. BIOPAPUA, ST. DW 3732, 8º16’S, 150º29’E, 340–358 M, OFF KIRIWINA ISLAND, 2 DD; ST. DW 3734, 8º16’S, 150º30’E, 389 M, 1 LV, 2 DD.

Description (holotype) (Fig. 18 C–D). Shell medium sized, narrowly fusiform, with high elevated spire (LWL/ SL 0.45) and attenuated, rather long canal. Shell of ca 2 protoconch whorls and 9.5 slightly convex teleoconch whorls. Protoconch globose, smooth, transition to teleoconch indistinct. Suture shallowly impressed. Besides inconspicuous growth lines, axial sculpture consisting of narrow, broadly spaced, sinuous, and slightly raised, prosocline ribs, 15 on penultimate whorl, 14 on last whorl, ribs running from suture to suture on spire whorls and becoming obsolete on shell base. Spiral sculpture consisting of two thin subsutural spiral threads and thin, distinct, sharp, broadly spaced and narrow cords, triangular in section; a smaller secondary cord between two larger cords on spire whorls; 16 cords on last whorl, 13 of which on shell base and canal more closely spaced. Three major cords forming large rounded beads at intersection with axial ribs. Aperture medium high, narrow elongate, 0.35 (together with canal) of SL. Outer lip chipped, sharp, evenly rounded. Columella short, convex, with two distinct closely spaced plaits. Callus narrow, of thin transparent glaze overlying parietal region. Siphonal notch absent. Canal well differentiated from aperture, narrow, long, slightly recurved and recurved abaxially. Shell color light yellowish. Periostracum thin, peeling, smooth, brownish.

Measurements (holotype). Holotype SL 15.7 mm, LWL 7.0 mm, AL (with canal) 5.5 mm, SW 3.5 mm (outer lip broken). Paratype SL 19.1 mm, LWL 8.1 mm, AL (with canal) 6.3 mm, SW 4.2 mm.

Paratype (Fig. 18 E–H), the largest specimen, very similar to holotype, with an intact outer lip and protoconch. Protoconch (Fig. 18 H) of two whorls, protoconch I smooth, globose, glossy whorls, protoconch II of one whorl, with 10 narrow, opisthocyrt ribs. Protoconch–teleoconch transition marked by appearance of spiral cords. Teleoconch consisting of 11.5 whorls. Outer lip thin, rounded, forming shallow notch on shoulder. Teleoconch whorls with 4 spiral cords, abapical-most one right above suture, last whorl with 21 cords.

Gross details of anterior foregut examined from rehydrated body of holotype. Proboscis long (compared to H. paradrillia and H. macrocephala), broad, straight. Midgut gland much larger than in H. paradrillia, adjoining proboscis base, consisting of long convoluted tubular part and a sac-like anterior part. Salivary glands not found. Rhynchostomal introvert absent. Radula with odontophore at proboscis base, but concealed within it. Radula (Fig. 16 A–C) short, consisting of 45 rows (5 nascent), length about 540 Μm (9.8% of AL) with strong alary processes embracing the anterior part of the membrane. Central tooth broad, with deeply arched anterior margin and single large cusp, bearing asymmetrical small denticles. Lateral teeth tall subtriangular plates, scoop-shaped, and with 5– 6 small denticles on inner side.

Distribution. The Philippines and Papua New Guinea, alive in 318–389 m, shells down to 427 m.

Etymology. Superstes (Latin) —survivor, reflecting the “living fossil” status of the species.

Remarks. The slender spire, long canal and pronounced columellar folds are shared with Vaughanites leptus. However, in the latter, the siphonal canal is significantly longer and more straight, and there is a little uncertainty whether V. superstes should be classified in Vaughanites. In older shells (Fig. 18 I), the columellar plaits appear less pronounced, although they are clearly visible when the shell is rotated counterclockwise.

The only species to which Vaughanites fallax bears some superficial resemblance is “ Terebra ” swobodai Bratcher, 1981, from the Philippines. V. fallax can easily be recognized by its much higher aperture, much longer siphonal canal, and the distinct columellar plaits.