Benthofascis biconica
Creators: name: Tucker, J. K.
name: Tenorio, M. J.
name: Stahlschmidt, P.
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Neogastropoda
Conorbidae
Benthofascis
Benthofascis biconica

description: <i>Benthofascis biconica</i> (Hedley, 1903) Figures 1, A–F; 4, A–D <b>Type material.</b> Holotype is AMS C.016448, shell length 18 mm, shell width 8 mm. <b>Type locality.</b> 35–37 m, Shoalhaven Bight, New South Wales, Australia <b>Other specimens.</b> AMS C.468235, 4 specimens from 71–77 m deep, 5.7 km E of Mistral Point, Sydney, New South Wales, 33º56.470'S, 151º19.630'E, dredged, 20 July 1972, Station: SBS 2; AMS C.468237, 2 specimens from 9 m, Twofold Bay, New South Wales, 37º5'S, 149º55'E; AMS C.388783, 2 specimens from 66 m, off North Head, Sydney, New South Wales, 33º49.5'S, 151º18.1'E; AMS C.468232, 1 specimen from 71–77 m, 5.7 km E of Mistral Point, Sydney, New South Wales, 33º56.470'S, 151º19.630'E (wet); AMS C.468233, 1 specimen from 77 m, 5 km E of Long Bay, Sydney, New South Wales, 33º58.150'S, 151º18.020'E, dredged 20 February, 1973, Shelf Benthic Survey. <b>Range.</b> New South Wales, Australia. <b>Description.</b> Shell solid, biconical, slightly angled at the shoulder, of more than six whorls. Color apparently flesh-tint. Sculpture: below the shoulder the shell is furrowed by numerous fine spiral grooves, crossed by arcuate growth lines, above the furrows are broader and fewer. Aperture narrow, sinus sutural and deep, outer lip appears to have curved far forward, columella angled in center, spreading broadly and with a small anterior plication. Length, 18 mm; breadth, 8 mm (quoted from Hedley 1903, p. 385–386). Inner shell walls are resorbed (Fig. 1E). The operculum is leaf-shaped with a terminal nucleus. It is fairly large and covers most of the apertural opening. The operculum of a specimen (AMS C.468234) with a shell length of 15.2 mm measured 3.25 mm in length. We examined a total of 28 specimens that could be accurately measured. Shell length for these averaged 26.4 mm (range = 10.1– 41.8 mm). Shell width averaged 10.7 mm (range = 4.6–17.6 mm). The radula has a barb and blade at its anterior end (Figs. 4A–D). The barb is sharply tipped and this distal tip is curved away from the shaft of the tooth. The barb is about one-third as long as the blade. The distal end of the blade slopes towards the shaft of the tooth and is not much elevated above the shaft of the tooth. There is no anterior fold but there is a C-fold. This fold demonstrates that the tooth is enrolled a minimum of 360 degrees. There are no serrations and no terminating cusp. There is a fold on the shaft of the tooth that begins posterior to the distal end of the blade. This fold extends to the waist of the tooth (Figs. 4A &amp; C). The tooth has a slight but distinct waist. <b>Discussion.</b> Hedley (1903) aptly described the holotype of this species (Figs. 1A–C). Laseron (1954) reproduced Hedley's figure and correctly identified the species. However, some subsequent authors have misidentified specimens of <i>Benthofascis pseudobiconica</i> as <i>B. biconica</i> (e.g. Powell 1966; Wilson 1994; Tucker &amp; Tenorio 2009). These two species are similar to each other but differ in shell shape. The shoulders of <i>B. biconica</i> are distinctly angular (Figs. 1A, D, &amp; F), whereas those of <i>B. pseudobiconica</i> are not (Figs. 2E, G, &amp; H). The more angular shoulders give <i>B. biconica</i> a stouter appearance compared to the long-bodied <i>B. pseudobiconica</i>. Two other species have subangular shoulders, namely <i>B</i>. <i>angularis</i> (Figs. 2A &amp; C) and <i>B. lozoueti</i> (Figs. 3I, K, &amp; L). The latter species has a nearly smooth protoconch with more than 2 whorls (Fig. 3J), a feature unique among the <i>Benthofascis</i> species. Besides that <i>B. lozoueti</i> is unique among <i>Benthofascis</i> in that the inner shell walls are not remodeled (Fig. 3H). We were able to confirm via x-ray that all other species of <i>Benthofascis</i> remodel the inner shell walls. <i>B</i>. <i>angularis</i> does not have the punctate sutural ramps similar to those that <i>B</i>. <i>biconica</i> has. The body whorl ornamentation of <i>B. conorbioides</i> differs from that of <i>B. biconica</i>. The former species (Figs. 3A, B, &amp; D) and the two fossil species (Figs. 3E &amp; F) have spiral grooves that are widely spaced and that cover the entire body whorl rather than the more closely spaced grooves of <i>B. biconica</i> and <i>B. pseudobiconica</i>. The body whorls of <i>B. lozoueti</i> (Figs. 3I, K, &amp; L) and B. <i>angularis</i> (Figs. 2A &amp; C) are almost smooth. We illustrate the radulae of two of these species with micrographs and with drawings that show the internal structure of the teeth for the first time. Previous drawings (e.g., Powell, 1966) were misleading as they suggested that the teeth were simple hollow tubes with no internal structure (see Tucker &amp; Tenorio, 2009). Electron micrographs available for <i>B. lozoueti</i> (Sysoev &amp; Bouchet, 2001) also do not show internal structures. The radulae of <i>B. biconica</i> and <i>B. pseudobiconica</i> that we were able to examine had unexpected structures. There is a definite C-fold and a slight waist both features that were not obvious in previously published drawings of radulae from <i>Benthofascis</i>. This is important because it demonstrates that the tooth is enrolled more than 360 degrees. Moreover a fold is obvious along the shaft of the tooth in all three species. This fold may be homologous to the shaft fold that characterizes the Conilithidae (Tucker &amp; Tenorio, 2009). However, this fold is not a shaft fold because it appears that in <i>Benthofascis</i> this fold is an internal one associated with the enrollment of the tooth. The shaft fold of the Conilithidae is an external structure.
description: Published as part of <i>Tucker, J. K., Tenorio, M. J. &amp; Stahlschmidt, P., 2011, The genus Benthofascis (Gastropoda: Conoidea): A revision with descriptions of new species, pp. 1-14 in Zootaxa 2796 (1)</i> on pages 3-5, DOI: 10.11646/zootaxa.2796.1.1, http://zenodo.org/record/5290155
description: {"references": ["Hedley, C. (1903) Scientific results of the trawling expedition of H. M. C. S. \" Thetis \" off the coast of New South Wales, in February and March, 1896. Mollusca. Part II. Scaphopoda and Gastropoda. Memoirs of the Australian Museum, 4, 327 - 402, pls. 36 - 37.", "Laseron, C. F. (1954) Revision of the New South Wales Turridae. Royal Zoological Society of New South Wales Australian Zoological Handbook. Royal Zoological Society of New South Wales, Sydney, 56 pp., 12 pls.", "Powell, A. W. B. (1966) The molluscan families Speightiidae and Turridae an evaluation of the valid taxa, both Recent and fossil, with lists of characteristic species. Bulletin of the Aukland Institute and Museum, 5, 1 - 184, 23 pls.", "Wilson, B. (1994) Australian Marine Shells. Vol. 2 (Prosobranch Gastropods Part Two (Neogastropods )). Odyssey Publishing, Kallaroo, Western Australia, 370 pp.", "Tucker, J. K. &amp; Tenorio, M. J. (2009) Systematic Classification of Recent and Fossil Conoidean Gastropods, with Keys to the Genera of Cone Shells. ConchBooks, Hackenheim, Germany, 295 pp.", "Sysoev, A. V. &amp; Bouchet, P. (2001) New and uncommon turriform gastropods (Gastropoda: Conoidea) from the South-West Pacific. Memoires du Museum National d'Histoire Naturelle, Paris, serie A, Zoologie, 185, 271 - 320."]}