Cerodrillia porcellana, 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 : 77-79

Cerodrillia porcellana , new species

( Plate 32 )

Type material. Holotype 9.3 x 3.9 mm, D. Steger! Aug–Oct 1952 (DMNH 240354); 17 paratypes from the type locality: 2 spec., 7.4 x 3.0 & 8.0 x 3.0 mm, (DMNH 240356); 3 spec., 7.4 x 2.8, 7.7 x 3.0, and 4.7 x 2.5 mm, (MCZ 279174); 3 spec., 7.6 x 2.3, 8.0 x 3.1, and 7.4 x 2.2 mm, (ANSP 323999); 1 spec., 6.0 x 2.6 mm (UF 21573); 7 spec., 9.0 x 3.7, 7.7 x 3.0, 8.0 x 3.3, 7.7 x 3.0, 6.7 x 2.6, 8.8 x 3.5 & 6.1 x 2.9 mm (UF 158086). A single paratype, 10.6 x 4.2 mm, is from Campeche Bank off Yucatan, “Station 1244”, L. Kornicker! (USNM 667765).

Type locality. 32–56 km ENE to NNW of Arcas Cays, Campeche Bank, Gulf of Mexico, in 44– 48 m.

Range and habitat. Campeche Bank. Specimens have been reported from 16–48 m depths, from on mud or sandy mud.

Description. Shell small (to 10.6 mm), broadly fusiform, glossy, truncated anteriorly with a narrow canal; body whorl approximately 60% of total length. Whorls convex, sutures impressed but undulant over ribs of the previous whorl. Protoconch paucispiral with 1½–2 smooth glossy whorls. Axial sculpture of broad ribs that extend from suture-to-suture on spire whorls but fade on shell base; 9–11 ribs on the penultimate and 7–10 on last whorl to varix. Ribs with ridged, not rounded crests; slightly recurved in sulcal area. Spiral sculpture limited to ridges on shell base below whorl periphery, strongest on anterior fasciole. Sulcus absent, shoulders with a slight recurve in the ribs just below suture. Varix an expanded rib, cup handle shaped, positioned behind the anal sinus. Outer lip thin, edge extending in a smooth arch from, and congruent with the anterior edge of the anal sinus, to the anterior canal; stromboid notch close to the anterior end and just a ruffle in the lip’s edge. A short narrow axial fold present between varix and edge of outer lip. Anal sinus on shoulder, shallow, sides divergent. Inner lip moderately wide, emarginated and erect anteriorly with a parietal callus joining the outer lip at the suture. Anterior canal short, open, and unnotched; anterior fasciole not swollen. Color porcellaneous white.

Remarks. Nomenclature. Multi-specimen lots given the name “ Cerodrillia arcas ” by Dan Steger were distributed to museums in anticipation of publication of their description (around 1970). Lots deposited by Steger were found in ANSP, FLMNH, MCZ and DMNH, and perhaps others exist. They are typically a mix of juvenile and adult specimens, with juvenile and adult specimens of Lissodrillia arcas , new species mixed in (additional detail under the description of that species). Juveniles of the two are difficult to distinguish and most in poor condition, so some juveniles of C. porcellana were likely left out of the type series given above. Taxonomy. Cerodrillia porcellana has all the shell characters that are diagnostic of Cerodrillia , including suture-to-suture axial ribs, a cup-handle-like varix just behind the anal sinus, and a polished shell surface with faint spirals confined to the shell base. Its whorl shoulders are less well defined than most of its congeners. Variability. The average total length of 18 specimens is 7.67 mm (4.7–10.6 mm), and their average W/ L ratio is 0.392. Identification. Cerodrillia porcellana is usually distinguished from known congeners by its pure porcelain-white color. C. porcellana is similar to C. yucatecana , new species, C. occidua , new species, and C. sanibelensis , new species. Cerodrillia yucatecana differs in possessing ribs with round, not ridged crests, a longer more tapering anterior end, and a different color—white to pale golden brown, not porcellaneous white. Cerodrillia occidua differs in possessing more convex ribs and sigmoid ribs, and is generally larger (11.20 versus 7.67 mm, average length). From to C. sanibelensis it differs in having more evenly rounded and more numerous ribs (9–11 versus 6–7 on the penultimate whorl).

Etymology. The Porcellaneous Cerodrillia . The minor epithet is from the Neo-Latin porcellanus meaning of porcelain. The shell color and glossy surface are reminiscent of pure white bone china.

Figures

PLATE 32. Cerodrillia porcellana, new species. Upper panel. Fig. 1: holotype, NNW of Arcas Cays, Mexico (DMNH 240354), ventral lateral & dorsal views. Lower panel, paratypes. Figs. 2 – 7, 9 – 13: NNW of Arcas Cays, Campeche Bank, Mexico. Figs. 2, 5, 13: MCZ 279174; Figs. 3, 12: DMNH 240356; Figs. 4, 11: ANSP 323999; Figs. 6 – 7, 9 – 10: UF 158086. Fig. 8: off Yucatan, Campeche Bank, Mexico (USNM 667765).