Benthofascis angularis, Tucker & Tenorio & Stahlschmidt, 2011

Tucker, J. K., Tenorio, M. J. & Stahlschmidt, P., 2011, The genus Benthofascis (Gastropoda: Conoidea): A revision with descriptions of new species, Zootaxa 2796 (1), pp. 1-14 : 6-7

Benthofascis angularis new species

Figures 2 , A–D

Type material. Holotype in MNHN 23067and paratype in P. Stahlschmidt collection both found among red and green algae, low limestone reef with some taller kelp, 12–15 m, Duke of Orleans Bay, Esperance , southwest Western Australia.

Type locality. 30 m, off Cape le Grande, Esperance , southwest Western Australia .

Range. Known only from Esperance, Western Australia.

Description. Shell is small but is solid and ovate-fusiform. The holotype is 27.5 mm long and 11.1 mm wide. The paratype is 25.3 mm long and 11.0 mm wide. Color pattern consists of yellow bands over white. Three colored bands are present on the teleoconch whorls with one at the shoulder, one near midbody and the other at the anterior end. The midbody and anterior end bands may fuse into a single band. Spire is mostly white but a pale yellow band is located on the last teleoconch whorl. The holotype has 5.5 whorls including the protoconch. Sculpture on the protoconch consists of fine spirals. There are 4 or 5 spirals on the early sutural ramps of the teleoconch. The spirals are more pronounced than the axials, which appear to be enhanced growth lines. The number of spirals is reduced on the sutural ramps of the outer teleoconch whorls to two. Here, only growth lines cross the interspaces between the spirals. The body whorl is ornamented by spiral grooves. On the posterior half of the shell these grooves are widely spaced but they are set closer together on the anterior half of the body whorl. They are not overly distinct and best seen under magnification. The sides of the body whorl are slightly convex anterior to the shoulder angle. The shoulder is distinct almost carinate. The aperture is narrow with a deep sinus, the lip is thin, straight and is produced medially. Inner shell walls are resorbed ( Fig. 2D ). The columella is nearly straight but does have a medial prominence. There is also a groove near its posterior end just where the columella meets the body whorl. This forms a denticle inside the aperture. The anal sinus is not symmetrical and is deepest at the suture. The protoconch is paucispiral, blunt and swollen looking. The operculum is leaf-shaped with a terminal nucleus ( Fig. 2A ). It is fairly large and covers much of the apertural opening. The operculum of the holotype is 5.92 mm long. The radula was not observed.

Discussion. This species can be distinguished from all other species of Benthofascis by the angular, almost carinate shoulder. In respect to the shell shape Benthofacies angularis is most similar to B. lozoueti . Both species are easily separated by the smooth body of B. angularis and the difference in the protoconch which is covered with minute and numerous spirals in B. lozoueti and only 5 spirals in B. angularis . In addition both species differ in respect to the inner whorls: in B. angularis the inner whorls are resorbed, but B. lozoueti appears to lack internal shell remodelling. The sutural ramps of early teleoconch whorls have reduced development of axials resembling B. pseudobiconica ( Fig.2J ). However, the shoulder of that species is much less angular than that of B. angularis . The shoulder of B. biconica ( Figs. 1A & B ) is subangular but not as angular as that of B. angularis . The latter species also differs in ornamentation of the sutural ramps of early teleoconch whorls from B. biconica . The spirals and axials on the sutural ramps of B. angularis are not strongly developed. On the outer sutural ramps simple growth lines replace the axials. In B. biconica , the spirals are much larger than the axials but the axials between adjacent spirals are much larger than are the growth lines.

This species is also the only Benthofascis species collected from Western Australia. More importantly, the holotype was collected in only 12–15 m water depth. With only a few exceptions other species of Benthofascis occur in deeper water.

Etymology. The name refers to the angular shoulders that characterize the species.

Figures

FIGURE 1. A–C. Holotype of Benthofascis biconica (AMS C.016448, 35–37 m deep, Shoalhaven Bight, New South Wales, Australia), height 18 mm, width 8 mm, ventral (A) and side (B) views with enlargement of spire (C). D–E. Benthofascis biconica (AMS C.468235, 5.7 km E of Mistral Point, Sydney, New South Wales, 33º56.470'S, 151º19.630'E, 71–77 m deep), heigth 29.8 mm, width 10.7 mm, ventral view (D) and x-ray (E). F. Benthofascis biconica (AMS C.468235, same locality data as above), height 17.9 mm, width 7.7 mm. G–H. Holotype of Benthofascis sarcinula (AMS C.19871, 203 m deep, 20 km miles E of Cape Byron, New South Wales, Australia), height 7 mm, width 4 mm, ventral view (G) and an enlargement of the spire (H). I–K. Benthofascis sarcinula (USNM 902892, SSE of Lakes Entrance, Gippsland Lakes, Victoria, Australia), height 16.6 mm, width 7.4 mm, ventral (I) and lateral views (J) with an enlargement of the spire (K). L–N. Benthofascis sarcinula (USNM 902893, Victoria, Australia), height 24.6 mm, width 10.7 mm, ventral (L) and lateral (M) views and an x-ray (N). Scale bars represent 1 mm.

FIGURE 2. A–D. Holotype of Benthofascis angularis new species (MNHN 23067, 30 m deep, off Cape le Grande, Esperance, southwest Western Australia), height 27 mm, width 11.1 mm, ventral (A) and lateral (B) views with enlargement of spire (C) and an x-ray (D). E, F. Holotype of Benthofascis pseudobiconica new species (MNHN 23069, off Cape Moreton, Queensland, Australia), height 39.8mm, width 12.8 mm, ventral (E) and lateral (F) views. G.Paratype of Benthofascis pseudobiconica new species (ANSP 424978, 183 m deep, off Cape Moreton, S. Queensland, Australia), height 35.3 mm, width 11.8 mm, ventral view. H–K. Paratype of Benthofascis pseudobiconica new species (USNM 902891, South Australia, Australia) height 36.4 mm, width 12.4 mm, ventral (H) and lateral (I) views with an enlargement of the spire (J) and an x-ray (K). Scale bars represent 1 mm.