Lissodrillia simpsoni (Dall, 1887)

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 : 252-254

Lissodrillia simpsoni (Dall, 1887)

( Plate 128 )

Pleurotoma Simpsoni Dall : Simpson (1887a: 53). Nude name, description not yet published.

Pleurotoma (Mangilia?) simpsoni Dall, 1887 in Simpson (1887b: 54–55).

Drillia ? Simpsoni (Dall, 1887) : Dall (1889a: 91).

Drillia simpsoni (Dall, 1887) : Dall (1889b: 98 [list]); Maury (1922: 151).

Cymatosyrinx simpsoni (Dall, 1887) : C.W. Johnson (1934: 136 [list])

Cerodrillia (Lissodrillia) simpsoni (Dall, 1887) : Powell (1966: 74 [list]); Abbott (1974: 272, sp. 3025).

Cerodrillia simpsoni (Dall, 1887) : Williams (2005: 1533 [upper group; lower group, left photo only]); Turgeon et al. (1988: 96 [list]).

Lissodrillia simpsoni (Dall, 1887) : Kaicher (1984: card 3895); Turgeon et al. (1998: 102 [list]).

Not this species, or unconfirmed extralimital and fossil reports.

Drillia ? simpsoni (Dall, 1887) : Dall (1890c: 37 [Caloosahatchee beds]); Dall (1903a: 1606 [Caloosahatchee beds]); Gardner & Aldrich (1919: 17 [Upper Miocene of South Carolina]).

Drillia simpsoni cingulata Gardner, 1948 : p. 270, pl. 37, figs. 4, 6 [fossil]. Type locality is Natural Well, Duplin County, N. C. Duplin Marl [Pliocene]; DuBar & Solliday (1961); Campbell et al. (1975: 117 [Plio-Pleistocene of the central Carolina coastal plain]); Campbell (1993: 95, 170, pl. 40, fig. 471 [Pliocene of the Yorktown and Chowan River Formations, Virginia.]).

Cerodrillia (Lissodrillia) simpsoni recticostata Fargo, 1953: 381 –382, pl. 19, fig. 3–3a. [fossil]. Type locality is North St. Petersburg, Florida Pliocene; Powell (1966: pl 11, fig. 7); Campbell et al. (1975).

Cerodrillia (Lissodrillia) simpsoni (Dall, 1887) : Dubar (1958 [Late Neogene of the Caloosahatchee]).

Cerodrillia simpsoni (Dall, 1887) : Nowell-Usticke (1959: 81, pl. 4, fig. 10 [St Croix]); Rios (1970: 126 [ Brazil]); Porter (1974: 246 [North Carolina]); Rios (1975: 132, pl. 40, fig. 594 [ Brazil]); Rios (1985: 138, pl. 47, fig. 631 [ Brazil]); Rios (1994: 160, pl. 53, fig. 717 [ Brazil]); Campbell et al. (1995 [Natural Well locality, Duplin stratotype, near Magnolia, North Carolina]). None of the figured specimens reported from Brazil appear to be Lissodrillia .

Cymatosyrinx simpsoni (Dall, 1887) : Du Bar (1962 [Pliocene? of North and South Carolina]).

Mangelia simpsoni (Dall, 1887) : Du Bar (1962: 37 [list; Maccama deposit, Pliocene? of North Carolina]).

Cerodrillia (Lissodrillia) simptoni [sic] (Dall, 1887): Odé (1991: 25–26 [Texas]).

Cerodrillia recticostata (Fargo, 1953) : Williams (2005: 1533).

Lissodrillia simpsoni (Dall, 1887) : García & Lee (2002: 12 [Louisiana; prob. = Lissodrillia robusta , new species]); Lee (2009: 124; no. 599 [E Florida; prob. = Lissodrillia levis , new species]).

Type material. Dall in Simpson (1887b: 54–55) states that two specimens of his newly described species were collected by C.T. Simpson in the same sample. Since more than one specimen was known to and possibly used by Dall in his description, the two constitute a type series (ICZN 2000 Article 72.4.1), and since no singe type was designated, they are considered syntypes (ICZN 2000 Article 73.2). Dall placed one of the specimens in USNM 61040, which is herein designated the lectotype. It measures 5.6 x 2.2 mm (5.75 x 2.1 mm are Dall’s measurements). The whereabouts of the second is unknown.

Type locality. Tampa Bay, Hillsborough Co., W Florida, in about 5 fms [9 m].

Other material examined. An additional 60 specimens were examined: 3 spec., 6.0 x 2.3, 5.2 x 1.9 & 4.8 x 1.9 mm, in 33–37 m, off Destin, Okaloosa Co., W Florida, 12 Oct 1941 (UF 257198); 43 spec., measured 24: 5.9 x 2.3, 5.6 x 2.3, 5.6 x 2.2 6.3 x 2.4, 6.1 x 2.2, 5.6 x 2.3, 6.0 x 2.2, 5.8 x 2.3, 6.2 x 2.4, 5.2 x 2.1, 5.9 x 2.3, 5.8 x 2.3, 6.0 x 2.3 5.7 x 2.2, 5.8 x 2.3, 5.9 x 2.3, 5.5 x 2.1, 5.6 x 3.1, 6.0 x 2.5, 5.8 x 2.2, 5.9 x 2.3, 5.7 x 2.4, 5.6 x 2.2 & 5.5 x 2.2 mm, in shallow water at low tide, St. Joe Bay, Gulf Co., W Florida (author’s coll.); 1 spec., 5.6 x 2.1 mm, ex batfish in 15–21 m, off Panama City, Bay Co., W Florida, J. Lightfoot! 1 Jan 1990 (UF 355961); 6 spec., 5.6 x 2.0, 6.6 x 2.2, 5.9 x 2.2, 5.9 x 2.2, 5.8 x 1.3 & 6.4 x 2.4 mm, in 30 m (ex batfish), off Panama City, Bay Co. (UF 470337); 7 spec., 4.7 x 1.9, 4.9 x 2.0, 5.4 x 2.2, 5.0 x 1.9, 5.5 x 2.0, 5.6 x 2.2 & 5.6 x 2.1 mm, in 73 m, 153 km W of Egmont Key, Hillsborough Co., W Florida, J. Moore! aboard Cavalier, Aug 1968 (UF 470336).

Range and habitat. W Florida (Okaloosa Co.; Bay Co.; Pinellas Co.; Hillsborough Co.). Dall (1889a: 91) states that specimens from off North Carolina (USFC Stations 2607 & 2619) are this species; however, this has not been confirmed and is considered unlikely. Reported from shallow water to 73 m.

Description. Shell very small (to 6.4 mm in total length), smooth and glossy, fusiform, anterior truncated, with up to 7½ slightly convex whorls, the last about 56% of total shell length; sculpted with ribs whose peripheries are near the anterior suture such that whorls appear to be cinched, or to sag. Aperture short, oval, with a short and wide but distinctly formed anterior canal. Protoconch of 1½–1¾ smooth, glossy, disproportionately large whorls, the first partially imbedded in the second such that the shell apex appears blunt. Axial sculpture of smooth, roundcrested ribs that run from suture-to-suture on spire whorls, evanesce below whorl periphery on shell base; 9–11 on penultimate and 4–8 on last whorl to varix. Ribs are wider than intercostal space, recurved on whorl shoulder and otherwise straight on spire whorls and slightly opisthocline on last whorl. Growth striae microscopic, oblique to ribs and recurved on shoulder. Varix an enlarged rib, up to twice the width of preceding rib and positioned ⅓–½ turn from edge of outer lip. Spiral sculpture absent. Sulcus absent; recurved ribs and striae on whorl shoulder mark past positions of the sulcus. Outer lip thin, translucent except for an axial folds, usually one nearest edge of outer lip; edge of lip, together with anal sinus, traces a reversed “S” from anal sinus to anterior canal; stromboid notch absent, or very weak. Anal sinus a deep wide notch with a round apex near suture, outer side divergent from inner. Inner lip thin, margined, free on anterior canal, recumbent on parietal wall, formed into an elongate, weak callus at the posterior end of the aperture. Anterior canal short, open, unnotched; fasciole not swollen. Color light to dark golden brown with white or white with rose-tinted ribs. Specimens occur with white color on just the rib crest, entire rib, or a continuous band of white across ribs and intercostal space.

Remarks. Taxonomy. Lissodrillia simpsoni has all of the characteristics of the genus: a small glossy shell with ribs suture-to-suture on spire whorls without a sulcus; inner edge of anal sinus and outer lip trace a reverse “S”; and the lack of spiral sculpture. Variability. The average total length of 42 specimens is 5.69 mm (4.7–6.6 mm); their average W/ L ratio is 0.391. Specimens from deeper water (73 m) are slightly smaller, almost entirely golden brown, have weaker ribs, and may represent a separate species (Pl. 128, Figs. 25–30). Identification. Lissodrillia simpsoni is similar to L. schroederi (Bartsch & Rehder, 1939) , L. robusta , new species, L. lactea , new species, and L. levis , new species. From L. schroederi it differs in possessing straighter ribs, and in being a different colorwhite or pink versus golden brown. Confirmed lots of L. simpsoni have been reported from “shallow” water to 73 m, mostly under 50 m depths, while those of confirmed L. schroederi occur in 30–183 m depths, mostly over 50 m. So there seems to be bathymetric separation of these two similar species. From L. robusta it differs in being slimmer in form, lacking the bulging ribs that characterize L. robusta . This latter species is also uniformly colored, without a broad central band like that of L. simpsoni . From L. lactea it differs in possessing less convex whorls, usually more ribs (9–11 versus 6–10 on the penultimate whorl), and in being a golden brown, not white. From L. levis it differs in being somewhat smaller 5.69 versus 6.74 mm in average total length), having more distinct and narrower ribs, and in possessing a different coloration.

Figures

PLATE 128. Lissodrillia simpsoni (Dall, 1887). Upper panel. Figs. 1 – 3: lectotype, Tampa Bay, Hillsborough Co. (USNM 61040). 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. Lower panel. Specimens from different localities and habitats, all W Florida. Figs. 4 – 8: off Panama City, Bay Co. (DMNH 107133); Figs. 9 – 11: off Destin, Okaloosa Co. (UF 257198); Figs. 12 – 24: St. Joe Bay, Gulf Co. (shallow water; author’s coll.); and Figs. 25 – 30: W of Egmont Key, Hillsborough Co. (deep water; UF 470336).