Splendrillia masinoi, 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 : 305-306

Splendrillia masinoi , new species

( Plate 156 )

Type material. Holotype 11.5 x 4.5 mm, R. Masino! (USNM 1291362); 2 paratypes from the type locality: 6.6 x 3.1 & 6.5 x 3.0 mm juveniles (USNM 1291363).

Type locality. 0.4 km WNW off Santa Martha Beach, Curaçao, Netherlands Antilles, in 34 m.

Range and habitat. Known only from the type locality.

Description. Shell small (to 11.5 mm in total length), fusiform, truncated anteriorly, of 9 angular whorls with sloping shoulders; last whorl approximately 57% of total shell length. Predominant sculpture is axial ribs; aperture oval, anterior canal short. Protoconch of 2 smooth, round whorls, the first not immersed in the second. Axial sculpture of strong ribs that run from suture-to-suture, to anterior fasciole on last whorl, lower, narrower and slightly recurved on shoulders; rib crests are narrower on shoulder, broader on whorl periphery; spaces between ribs about as wide as the ribs. 8–11 ribs on the penultimate whorl. Strong growth striae run obliquely over the ribs, are recurved on the whorl’s shoulder. Spiral sculpture of 6 spiral ridges on the anterior fasciole; except for growth striae, shell surface otherwise rather smooth as seen under a dissecting microscope. However, SEM images at 1,000x reveal a pattern of punctae arranged in rows, some regularly spaced, some not so (see Pl. 140, Figs. 5–6). The occasional row of joined punctae seen in other Splendrillia was not observed on the examined specimen. Sulcus concave, recurved ribs and striae mark the prior positions of the anal sinus. Varix broad and hump-like, about ⅓-turn from the edge of the outer lip, based on the length of the outer lip scar on the suture and position of parietal callus of the holotype. Outer lip is broken off on the only mature specimen. Anal sinus unknown; a complete anal sinus is not present. Inner lip thick and detached anteriorly, thin on the parietal wall, formed into a parietal callus posteriorly. Anterior canal open, unnotched; anterior fasciole slightly swollen. Color off-white with 2 thin reddish-brown spirals, one below the whorl periphery, the other very faint, close to the anterior fasciole, and axial streaks between ribs giving the appearance of penciled squares on the shell base. Also, a white band is present on whorl shoulder; shell apex and aperture are white. Large reddish-brown patch present on varix shoulder above the posterior-most reddish-brown spiral line.

Remarks. Taxonomy. The single adult type specimen of Splendrillia masinoi , new species is missing its outer lip, and hence the exact form of the anal sinus, outer lip, and anterior canal is unknown. This species exhibits characteristics of the genus with the absence of spiral sculpture, except on the anterior fasciole, a hump-like varix set about ⅓-turn from the outer lip and with a dark color patch. Ribs have not completely disappeared in the sulcus, and are not as oblique as is characteristic of most members of the genus. Identification. The type specimens were originally mistaken to be juvenile Decoradrillia pulchella (Reeve, 1845) but on closer inspection, the adult specimen was observed to have a slightly different color pattern and to be quite a bit smaller than that species. For contrast, compare Pl. 56, Fig. 19, a specimen of D. pulchella from the same locality with the adult S. masinoi . The brown spiral line is more diffuse in S. masinoi . Splendrillia masinoi is also similar to S. cruzensis , new species, and S. karukeraensis , new species. It differs in having more angular, broader ribs that are less oblique, and its color pattern is different.

Etymology. Robert Masino’s Splendrillia . Named for Mr. Robert Masino who collected the type material.

Figures

PLATE 156. Splendrillia masinoi, new species. Figs. 1 – 5: holotype and paratypes, 0.4 km WNW off Santa Martha Beach, Curaçao, Netherlands Antilles. Fig. 1: holotype, ventral, lateral, and dorsal views (USNM 1291362); Fig. 2: same, apical view, V = varix; Figs. 3 – 5: paratypes (USNM 1291363). Fig. 3: enlarged view of protoconch (not to scale) of same specimen shown in Fig. 4; Figs. 4 – 5: juveniles, ventral views.