Splendrillia bahamasensis, 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 : 283-287

Splendrillia bahamasensis , new species

( Plates 144 , 145 )

Type material. Holotype 16.2 x 6.2 mm (USNM 1291354); 24 paratypes, all from the type locality: 12 spec., 20.4 x 7.8, 16.1 x 6.2, 11.7 x 5.3 & 12.6 x 5.0 mm (USNM 1291355), 14.2 x 5.6, 16.6 x 6.5, 14.0 x 6.0 & 15.1 x 6.0 mm (ANSP 464994), 15.6 x 6.2, 14.2 x 5.6, 14.4 x 5.7 & 15.9 x 6.3 mm (UF 496645), NW side of N Elbow Cay; 2 spec., 15.6 x 5.9 mm (BMSM 14994) & 15.5 x 6.1 mm (BMSM 14992), NW side of N Elbow Cay; 3 spec., 12.3 x 4.9 & 12.5 x 4.9 mm (BMSM 14993) & 14.9 x 5.6 mm (BMSM 14995), NW side of Elbow Cays; 7 spec., 6.9 x 3.2, 7.6 x 3.4 & 7.8 x 3.4 mm (DMNH 240358), 9.8 x 4.1, 12.0 x 5.0, 12.0 x 5.2 & 14.8 x 5.7 mm (MZSP 122071), NW side of Elbow Cay. All types G. Mackintosh! Jan–Feb 1996.

Type locality. Elbow Cays, Cay Sal Bank, Bahama Is., at 9– 12 m.

Other material examined. An additional 84 specimens were examined, all from the Bahama Is.: Grand Bahama I.: 1 spec., 8.6 x 4.4 mm, in 3.7–5 m, S end, Wood Cay, P. Fallon!, 13 Jul 2000 (author’s coll.); 1 spec., 10.5 x 4.6 mm, off E side of Freeport Harbor inlet, 26°31'00"N, 078°46'30"W, Worsfold! (ANSP 374479); 7 spec., 2 largest: 11.5 x 4.3 & 11.9 x 5.1 mm, on algae covered rocks Freeport Dist., West End, 26°41'N, 078°58'W, J. Worsfold!, 1981 (ANSP 355569); 1 spec., 6.6 x 2.9 mm, in beach drift, West End, Bob Quigley! 1985 (H.G. Lee coll.); 8 spec., 6 largest: 11.8 x 5.1, 12.0 x 4.6, 9.4 x 3.6, 8.5 x 3.2, 9.4 x 4.0 & 14.2 x 5.3 mm, in 0–0.3 m, Settlement Pt., 26°42'15"N, 078°59'50"W, J. Worsfold! (ANSP 368585); 1 spec., 9.4 x 4.0 mm, in 24 m, Indian Cay, 26°42'45"N, 078°39'15"W, J. Worsfold! (ANSP 366925); 14 very young specimens, 2 measured: 7.0 x 3.0 & 8.5 x 3.5 mm, in 24 m, Gold Rock, 26°30'00''N, 078°22'00''W, J. Worsfold! (ANSP 369705); 5 spec., 4.3 x 2.5, 7.5 x 3.2, 8.1 x 3.5, 8.5 x 3.8 & 9.1 x 4.0 mm, in 24 m, Gold Rock, 20 mi E of Freeport, 26°35'N, 078°22'W, J. Worsfold! 1981 (ANSP 355563); 5 spec., 6.4 x 2.6, 9.4 x 4.0, 3.8 x 2.9, 8.7 x 3.7, & 4.3 mm, in 18–38 m, Lucaya , 26°29'45"N, 078°37'15"W, Worsfold! (ANSP 368081, 368082). Bimini Is.: 1 spec., 12.8 x 4.8 mm, in 1.8 m, Honeymoon Cove, Gun Cay, G. Mackintosh! 26 Feb 1996 (author’s coll.); 2 spec., 13.1 x 5.4 (author’s coll.) & 12.8 x 4.9 (USNM 900130) mm, in 4 m, Honeymoon Cove, Gun Cay, G. Mackintosh! 7 Apr 1994; 7 spec., 6 measured: 14.4 x 5.4, 13.9 x 5.4, 13.0 x 5.0, 10.1 x 4.1, 11.8 x 4.9 & 11.4 x 4.3 mm, Gun Cay, Bimini Is., McGinty! 21 May 1947 (UF 155958). Berry Is.: 1 spec., 10.0 x 4.2 mm, in 0.9 m, Hoffmans Cay, Pat Bingham! 20 Jun 1998 (H.G. Lee coll.). Exuma Cays: 4 spec., 10.4 x 4.6, 10.2 x 3.9, 11.3 x 4.5 & 11.6 x 5.0 mm, Ship Channel Cay, H. Dodge! (USNM 598737). Cay Sal Bank: 2 spec. 11.7 x 4.9 and 14.6 x 6.2 mm, in 9.8–11 m, E side of Dog Rocks, G. Mackintosh!, 15, 22 Feb 1996 (author’s coll.); 17 spec., 11.8 x 5.1, 12.9 x 5.3, 13.7 x 5.6, 13.5 x 5.5, 12.8 x 5.4, 13.5 x 5.4, 14.4 x 5.6, 14.4 x 5.7, 15.1 x 5.8, 14.8 x 6.0, 15.7 x 5.8, 15.5 x 6.1, 15.6 x 6.4, 16.4 x 6.4, 16.5 x 6.3, 16.2 x 6.2 & 13.7 x 5.5 mm, in 10 m, W side of Dog Rocks, G. Mackintosh! 24 Feb 1996 (author’s coll.); 1 spec., 11.5 x 4.5 mm, in 11 m, Cay Sal, G. Mackintosh!, 21 Apr 1994 (author’s coll.); 6 spec., 9.5 x 4.4, 10.2 x 5.5, 14.5 x 5.9 (all decollate) & 16.6 x 6.6 (author’s coll.), 9.2 x 4.2 & 9.2 x 4.3 (USNM 900111) mm, in 9 m, NW side of Elbow Cay, G. Mackintosh! 11 Jan 1966.

Range and habitat. Bahama Is. (Grand Bahama I.; Bimini Is.; Berry Is.; Exuma Cays, and Cay Sal Bank). Reported from shallow sandy bottoms and on hard surfaces in approximately 2– 24 m.

Description. Shell small (to 20.4 mm); fusiform, truncated anteriorly; glossy, whorls appressed, with sloping shoulders, convex below; body whorl large compared to the spire, 62.0% of total length. Protoconch paucispiral, of approximately 2 smooth round whorls, the tip of the first partially submerged; the second larger than the first. Axial sculpture of broad low ribs, crests of most ribs rounded anteriorly, becoming narrower near the sulcus then terminating at sulcus; evanesce on shell base. Ribs slightly oblique on early whorls, but progressively less so to body whorl; absent between the varix and edge of outer lip; about as wide as their interspaces. Ribs 8 on penultimate (6–10), 6 to varix on body whorl (4–8 on specimens with a varix). Heavy, compact growth striae cover shell surface. Spiral sculpture of microscopic spiral lines overall, mostly obscured by dense striae; with weak spiral ridges on the anterior fasciole. Sulcus broad, slightly concave, about ¼ spire whorl height, with trace swellings of reduced ribs. Varix broader and higher than preceding ribs, positioned about ⅓-turn from the edge of the outer lip. Outer lip smooth, thick, juts out somewhat and flexed inward at its edge; a slight indentation present anteriorly suggests a stromboid notch. Anal sinus moderately deep in mature individuals, adjoins suture near back of sinus, behind parietal callus. Inner lip very thin, not margined, except in old shells; erect anteriorly near tip of canal, thin on parietal wall, ends in a low callus at suture line. Anterior canal short but distinct, open, notched. Columella slightly twisted to the left anteriorly viewed ventrally; anterior fasciole slightly swollen. Color white with light pink to rose-colored bands mid-whorl and anteriorly; dark rose-colored streaks between ribs, and on apertural side of varix. Other forms are patterned similarly with brownish orange, or a combination of brownishorange and rose; all white forms also occur.

Remarks. Taxonomy. Splendrillia bahamasensis has all the important characteristics of Splendrillia : a smooth sulcus, axial ribs that terminate at the sulcus, a hump-like varix located about ⅓-turn from the edge of the outer lip, and an anal sinus that adjoins the suture at its rear. It is unique among Splendrillia in possessing heavy growth striae. Variability. The average length of 85 specimens is 12.24 mm (3.8–20.4 mm); the average W/ L ratio of 54 measured specimens is 0.413. Although color varies, no geographic pattern in the occurrence of pink or brownish orange forms could be discerned. All-white (dingy white) forms are rare. Identification. Splendrillia bahamasensis is commonly misidentified as S. coccinata (Reeve, 1845) by collectors and in museum collections; perhaps hampered by the absence of a published photograph of a S. coccinata type. Authors including the Bahama Is. in the range of S. coccinata have probably misidentified this species; the occurrence of verified specimens of S. coccinata is limited to the lower Lesser Antilles (see description of S. coccinata ). Splendrillia bahamasensis is most easily distinguished from its congeners by its heavy growth striae. It also differs from S. coccinata by its larger maximum total length (20.4 versus 10.0 mm), straighter and fewer ribs. Splendrillia bahamasensis is also larger than S. interpunctata (largest 20.4 versus 16.5 mm). The ribs of S. interpunctata are narrower, more oblique, and sharper at their crests. While growth striae are noticeably present in S. interpunctata , they are not as dense so the shell still appears translucent, which is not the case for S. bahamasensis .

Etymology. The Bahamas Splendrillia . Named for the country of the type locality and where all specimens reported here have been found.

Figures

PLATE 144. Splendrillia bahamasensis, new species. Upper panel. Figs. 1 – 3: holotype, N side, N Elbow Cay, Cay Sal Bank (USNM 1291354). Fig. 1: ventral, lateral, and dorsal views; Fig. 2: enlarged view of protoconch (not to scale); Fig. 3: apical view, V = varix, L = edge of outer lip. Lower Panel. Figs. 4 – 16: paratypes from Elbow Cay, Cay Sal Bank, Bahama Is. Fig. 4: ANSP 464994; Figs. 5, 8, 12, 16: USNM 1291355; Figs. 6, 10, 15: MZSP 122071; Fig. 7: BMSM 14993; Fig. 9: BMSM 14994; Fig. 11: BMSM 14995; Fig. 13: BMSM 14992; Fig. 14: UF 496645.

PLATE 145. Splendrillia bahamasensis, new species. Figs. 1 – 6: Dog rocks, Cay Sal Bank, Bahama Is. (author’s coll.); Figs. 7 – 13: Gun Cay, Bimini Is., Bahama Is. Figs. 7 – 11: (UF 155958); Fig. 12: (author’s coll.); Fig. 13: (USNM 900130); Figs. 14 – 21: Grand Bahama I., Bahama Is.: Fig. 14: (ANSP 366925); Fig. 15: (ANSP 368081); Figs. 16 – 17: (ANSP 368082); Fig. 18: (USNM 900111); Figs. 19 – 20: (ANSP 368585); Fig. 21: (ANSP 369705); Fig. 22: Exuma, Bahama Is. (USNM 598737); Fig. 23: Hoffmans Cay, Berry Is., Bahama Is. (H. G. Lee coll.); Fig. 24: Grand Bahama I., Bahama Is. (ANSP 368585); Figs 25 – 27: paratypes, Elbow Cays, Cay Sal Bank, Bahama Is. Fig. 25: UF 496645; Fig. 26: ANSP 464994; Fig. 27: UF 496645.