Splendrillia panamensis, 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 : 306-307

Splendrillia panamensis , new species

( Plate 157 )

Type material. Holotype 14.5 x 5.5 mm (USNM 900143); 3 paratypes: 7.5 x 3.7, 11.6 x 4.6 & 13.1 x 5.0 mm, in 8 m, Porto Viejo, San Juan Joaquin I., Panama (USNM 900144).

Type locality. Hollandes Cays, San Blas Is., Panama.

Range and habitat. Central Panama, Caribbean coast. Reported from 8 m (at Porto Viejo, Panama).

Description. Shell small sized (to 14.5 mm in total length), glossy, fusiform, truncated anteriorly; of approximately 8¾ convex whorls; body whorl large, approximately 59% of total shell length; concave sulcus and nodulose ribs give the shell a turreted outline; axial ribs the predominant sculptural element; aperture an elongate oval. Protoconch paucispiral, of 1½–1¾ smooth whorls, first whorl not immersed in second, second larger than and slightly greater in diameter than the first teleoconch whorl. Axial sculpture of broad, almost straight, bulging ribs with low round crests anteriorly that become ridged posteriorly; ribs terminate abruptly at sulcus forming an angular shoulder, obsolete in sulcus; end at anterior fasciole on shell base. Ribs number 8–10 on penultimate, 6–8 on last whorl to varix, about as broad as their interspaces. Shell surface covered with microscopic growth striae. Spiral sculpture of microscopic spiral lines, most visible in sulcus, obscured by growth striae elsewhere; becoming ridge-like on shell base, heaviest on anterior fasciole where they number 5–7. Sulcus concave, ⅓-spire whorl height; devoid of sculptural detail except fine growth striae. Varix prominent, hump-like, and positioned about ⅓- turn from the edge of the outer lip. Outer lip smooth, somewhat flattened from the varix to lip’s edge; thickened and slightly flexed inward along edge from anterior side of anal sinus to anterior canal; axial fold near lip edge. Lip edge forms a flat arc from anal sinus to stromboid notch. Stromboid notch shallow. Anal sinus deep, adjoins suture at rear behind parietal callus; sinus offset laterally from axis of shell by callus, and together with the outward bend of the outer lip, appears spout-like. Inner lip thick and erect on anterior canal, thin and unemarginate on parietal wall, and formed into a callus posteriorly, which forms the parietal side of the anal sinus. Anterior canal short but distinct, open, notched; anterior fasciole slightly swollen. Color white.

Remarks. Taxonomy. Splendrillia panamensis has all the characteristics of Splendrillia . It possesses a concave sulcus, devoid of sculptural elements, a smooth shell surface, hump-like varix, and anal sinus that is joined at the sulcus behind the parietal lobe. It is unique in the form of the anal sinus, which is produced spout-like. Variability. The four specimens have an average total length of 11.68 mm (7.5–14.5 mm), and a W/ L ratio of 0.413. Identification. Splendrillia panamensis is very similar in shape and size to S. interpunctata (E.A. Smith, 1882) , but differs chiefly in possessing a spout-like anal sinus, aperture that narrows anteriorly, and straighter ribs, although both species are similarly acutely shouldered. It is white in color, whereas S. interpunctata is generally pink, rarely all-white. It differs from S. grandis , new species in being smaller (11.68 versus 17.95 mm average total length), in having more angular shoulders, and a different color. Splendrillia grandis is light caramel in color with a dark caramel mid-whorl spiral band, not all-white.

Etymology. The Panamanian Splendrillia . Named after the country of its type locality.

Figures

PLATE 157. Splendrillia panamensis, new species. Figs. 1 – 3: holotype, Hollandes Cays, San Blas Is., Panama (USNM 900143). Fig. 1: ventral, lateral & dorsal views; Fig. 2: enlarged view of protoconch (not to scale); Fig. 3: apical view, V = varix, L = edge of outer lip. Figs. 4 – 6, paratypes, San Juan Joaquin I.: Porto Viejo, Panama (USNM 900144), ventral views.