Bellaspira amplicostata, Fallon, Phillip J., 2016

Fallon, Phillip J., 2016, Taxonomic review of tropical western Atlantic shallow water Drilliidae (Mollusca: Gastropoda: Conoidea) including descriptions of 100 new species, Zootaxa 4090 (1), pp. 1-363 : 24

Bellaspira amplicostata , new species

( Plate 4 )

Type material. Holotype 7.4 x 3.5 mm (UF 449328); 11 paratypes, 6.6 x 3.0, 7.3 x 3.2, 8.0 x 3.2, 6.9 x 3.0, 7.0 x 3.2, 7.1 x 3.0, 7.2 x 3.2, 6.6 x 3.0, 7.1 x 3.2, 6.2 x 2.9 & 7.5 x 3.3, all from the type locality (UF 449327). Riley Black! 20 Apr 1967.

Type locality. NE of Contoy Light, Contoy I., Quintana Roo, Mexico, in 183 m.

Range and habitat. Known only from the type locality.

Description. Shell very small (to 7.5 mm), stoutly fusiform, truncated anteriorly, glossy, with up to 7 convex whorls, suture impressed—undulates over preceding whorl’s ribs; heavily ribbed. Last whorl large, approximately 64% of total shell length. Protoconch of 2 whorls, the first partially immersed in the second giving the shell apex a bluntly round shape. Axial sculpture of broad, round ribs that extend from suture-to-suture, evanesce on body whorl at anterior fasciole, intercostal space narrower than ribs; 7–8 on penultimate and 4–6 on body whorl to varix. Growth striae present, heaviest on rib sides. Vari x consists of a slightly thickened last rib within ⅓-turn of the edge of the outer lip. Spiral sculpture of very fine, weak incised lines over the entire teleoconch. Sulcus absent, there is little change in the ribs in the sulcal area. Outer lip thin, and forms a continuous low arc to the end of the anterior canal. No evidence of a stromboid notch present. Anal sinus a wide but shallow indentation of outer lip edge when shell is viewed laterally; an inverted V-shape at suture when shell viewed ventrally; callus present on both the parietal wall and inside of outer lip of sinus. Inner lip recumbent, margined, broader along columella, narrower on parietal wall. Anterior canal short, open, curved to the left viewed ventrally; end with a shallow notch. Anterior fasciole not swollen. Color off white with apex and intercostal space a light creamy brown.

Remarks. Taxonomy. Bellaspira amplicostata exhibits the characteristics of the genus with axial ribs that extend from suture-to-suture (in this case without any change in the sulcal area), with a varix consisting of a slightly expanded rib, with an anal sinus typical of the genus, and with surface microsculpture of fine spiral incised lines. The incised lines in this species are feeble, even obsolete on some portions of the shell surface, perhaps due to wear. Also different are the heavy growth striae that appear on the sides of the ribs, but are reduced in the intercostal space. Striae are generally weaker in other species of Bellaspira , the spiral lines stronger. Variability. The average length of 12 examined specimens is 7.08 mm (6.2–8.0 mm); their average width to length ratio (W/L) is 0.445. No variation in color is observed in the single type lot of 12 specimens. Identification. This shell is unique with its uniformly but narrowly spaced wide ribs. From B. pentagonalis (Dall, 1889) it differs in having 7–8 ribs, not 5 on the penultimate and whorl, and in coloration—the darker color is between the ribs, not on rib crests. From B. aurantiaca , new species it differs in possessing broader ribs, and a different coloration.

Etymology. The Large-ribbed Bellaspira , from the Latin adjectives amplus (large) and costatus (ribbed). Named after an outstanding feature of this species—its large ribs.

Figures

PLATE 4. Bellaspira amplicostata, new species. Upper panel. Fig. 1: holotype, NE of Contoy Light, Contoy I., Quintana Roo, Mexico (UF 449328), ventral, lateral & dorsal views. Lower panel. Figs. 2 – 11: paratypes, all from the original type lot (UF 449327).