Syntomodrillia carolinae Bartsch, 1934

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: 319-320

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Syntomodrillia carolinae Bartsch, 1934


Syntomodrillia carolinae Bartsch, 1934 

( Plate 165View PLATE 165)

Syntomodrillia carolinae Bartsch, 1934: 27–28  , pl. 8, figs. 1, 4, 8.

Splendrillia (Syntomodrillia) carolinae (Bartsch, 1934)  : Powell (1966: 84); Abbott (1974: 275, species 3106). Splendrillia carolinae (Bartsch, 1934)  : Williams (2005; 2006; 2009: species 1584).

Not this species or unconfirmed extralimital reports.

Splendrillia (Syntomodrillia) carolinae (Bartsch, 1934)  : Rios (1985: 139, pl. 47, fig. 641 [S Brazil]); Rios (1994: 163, pl. 54, fig. 733 [S Brazil]); Rios (2009: 314, fig. 798 [S Brazil]).

Splendrillia carolinae (Bartsch, 1934)  : Rios (1975: 134, pl. 40, fig. 605 [S Brazil]); Absalão (2007 b: 132 [N Brazil: Abrolhos National Park, Bahia]).

Type material. Holotype 6.1 x 2.1 mm (USNM 430853).

Type locality. R/V Caroline Sta. 10, Johnson-Smithsonian Deep Sea Exploration, off Morro Castle Light, Cabras I. [at entrance to San Juan Bay], Puerto Rico, between 18 ° 29 ' 20 "N, 66 °05' 30 "W and 18 ° 30 ' 24 "N, 66 °04' 15 "W, in 120–160 fms [219–293 m].

Other material examined. An additional 28 specimens were examined: Puerto Rico: 2 spec., 5.8 x 2.3 & 6.0 x 2.2 mm, in 183 m, R/V Caroline Sta. 10, off Morro Castle Light, Cabras I., Puerto Rico (USNM 430999; noted as “topotypes” by Bartsch—depth differs from that of the type locality); 3 spec., 5.4 x 2.1, 5.1 x 2.0 & 5.3 x 2.2 mm, USFC Sta. 134, Mayaguez Harbor, Puerto Rico (USNM 161151). Antigua: 1 spec., 6.6 x 2.4 mm, in 219 m, SUI 1918 Exped. Sta. 115, off English Harbor (USNM 502441). Guadeloupe: The data, including barcode accession numbers of the 16 specimens live-taken during the MNHN KARUBENTHOS 2012 expedition are given below.

Colombia: 1 spec., 5.9 x 2.3 mm, in 58 m, Changue Bay, Cabo de la Vela, Guajira Dept. (author’s coll.). French Guiana: 1 spec., 9.1 x 3.2 mm, in 115 m, GUYANE 2014 Sta. CP4348, 05° 46 'N, 51 ° 23 'W, 27 Jul 2014 (MNHN, not cataloged); 1 spec., 7.9 x 2.8 mm, in 95–97 m, GUYANE 2014 Sta. CP4402, 06° 18 'N, 52 ° 13.3 'W, 8 Aug 2014 (MNHN, not cataloged); 3 spec., 7.8 x 3.0, 7.1 x 2.6 & 7.1 x 2.6 mm, in 94 m, GUYANE 2014 Sta. DW4359, 06° 52.2 'N, 53 °02.6'W, 30 Jul 2014 (MNHN IM- 2012-43465).

Range and habitat. Puerto Rico (off N coast); Antigua; Guadeloupe; Colombia (Guajira Dept.); French Guiana. Reported from 58– 293 m.

Description. Shell very small (to 9.1 mm total length), fusiform, glossy, semi-translucent with up to 7 ½ symmetrically rounded whorls (peripheries mid-whorl), the last approximately 59 % of total length. Aperture oval, widest just below the anal sinus. Axial ribs are the predominant sculptural element. Protoconch of a little more than 2 whorls, smooth, round. Axial sculpture of broad, slightly opisthocline ribs that run suture-to-suture on spire whorls and evanesce at anterior fasciole on last; recurved on shoulders, giving them the overall appearance of being sigmoid; ribs about as wide as intercostal space, rib crests ridged, number 12–13 on penultimate and 8–12 on last whorl to varix. Growth striae present. Varix is convex, rib-like, straight, higher and wider than adjacent ribs. Spiral sculpture of grooves between ribs, anterior to shoulder, becoming stronger anteriorly. Bartsch states that spirals are “absent on all the whorls but the last”; however, a few faint spirals are present near the suture of the penultimate whorl of the holotype. Sulcus absent; ribs slightly recurved marking past positions of anal sinus on shoulder to sulcus; spiral sculpture absent on shoulder. Outer lip slightly flattened from the base of the varix; flexed in to aperture at edge of lip; profile of edge from anal sinus to anterior canal is a low curve, with a shallow stromboid notch anteriorly. Several strengthening axial folds run parallel to curvature of lip edge. Anal sinus a deep notch adjacent to suture with round apex, sides parallel to slightly divergent. Inner lip recumbent, emarginated, thick anteriorly on columella, thinner on parietal wall, forming a weak lobe over roof of aperture and side of anal sinus. Anterior canal moderately long, open, mostly straight but may be skewed slightly to the right near its end when viewed ventrally and flared at its end in fully grown individuals; unnotched; fasciole with 5 spiral ridges. Color white, off-white, or light golden brown.

Remarks. Taxonomy. Syntomodrillia carolinae  possesses the characteristics of the genus as described by Woodring: a small species having a narrowly fusiform shell with ribs extending from suture-to-suture, and to the anterior fasciole on the last whorl, with spiral threads between the ribs, principally below the sulcus, and a varix about ⅓-whorl from the edge of the outer lip. Variability. The 30 specimens have an average total length of 5.91 mm (4.9–9.1 mm), and an average W/ L ratio  of 0.384. Identification. Syntomodrillia carolinae  is similar to S. portoricana  , new name, S. cookei  (E.A. Smith, 1888), and S. lissotropis (Dall, 1881)  . From S. portoricana  it differs in having whorl peripheries at mid-whorl, not generally below mid-whorl, a more translucent shell (when fresh), more and narrower ribs (10–14 versus 8 – 2 on the penultimate whorl), a straight anterior canal not bent to the right when viewed ventrally, and fewer spiral threads on the anterior canal (3–5 versus 9–10). From S. cookei  it differs in being stouter, ribs with ridged, not round crests, and in having more prominent intercostal spiral threads. The spiral sculpture in S. cookei  is often quite faint and best seen under a dissecting microscope on the post varical portion of the outer lip. From S. lissotropis  it differs in more and deeper spiral grooves between ribs and in having a round, not sagging whorl profile. Bartsch (1934: 28) compares S. carolinae  with S. woodringi  , stating that it is stouter, has fewer spiral threads on its anterior fasciole, and more slender nuclear whorls.