Cerodrillia Bartsch & Rehder, 1939

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 : 55

Genus Cerodrillia Bartsch & Rehder, 1939

Type species, by original designation: Cerodrillia clappi, Bartsch & Rehder, 1939 (Recent, Hawk Channel, Key West, Florida Keys).

Diagnosis. According to Bartsch & Rehder (1939: 127), shells waxy in appearance, elongate-turreted, with a smooth protoconch that passes directly to adult sculpture, a short anterior channel, strong recurved axial ribs that extend to the suture, a deep anal sinus, a stromboid notch, and faint spiral striations that strengthen on the shell base, strongest on the columella.

Key characteristics. The presence of all the following characteristics, in addition to those that define the family, is diagnostic of species of Cerodrillia and separates the genus from other TWA drilliid genera:

1. A stout, fusiform shell (W/L>= 0.40), usually with a short anterior canal;

2. Axial ribs that usually extend from suture-to-suture, evanesce on the shell base. Ribs may be partially or wholly absent in the sulcus of older specimens;

3. Protoconch of 1¾–2 smooth whorls;

4. Spiral microsculpture primarily on shell base and includes incised grooves, threads, or ridges that strengthen anteriorly, strongest on anterior fasciole; remainder of shell surface may have very fine microscopic spiral lines but is usually smooth; and

5. Cup-handle-like varix behind anal sinus (within ¼-turn of outer lip edge, usually closer) such that the base of the mature shell appears lopsided (skewed to the right) when shell is viewed ventrally.

Nomenclatural notes. Lissodrillia, Bartsch & Rehder, 1939 was erected as a subgenus of Cerodrillia with the distinction that it is smaller (than C. clappi or C. perryae , the species then included) and has no spiral sculpture. The type species, Lissodrillia schroederi (Bartsch & Rehder, 1939) also lacks a cup-handle-like varix just behind the anal sinus, an important distinguishing characteristic of Cerodrillia . At the time, Bartsch & Rehder were probably not aware of the significance of the shape and position of the varix as a generic characteristic since they did not include it in their diagnosis of Cerodrillia . The species in hand were few and some of their specimens had incompletely developed varices and lips as seen in the holotype of C. perryae . Kaicher (1984: card 3895) raised Lissodrillia to generic status for Lissodrillia simpsoni (Dall, 1887) without explanation; Turgeon et al. (1998: 102) adopted this change. The elevation of Lissodrillia to generic status is support here principally because the group has a different varix and lacks spiral sculpture altogether.

Similar genera. Cerodrillia is most similar to Douglassia Bartsch, 1934 . See under that genus for an explanation of their differences. Some members of two other genera, Viridrillia Bartsch, 1943 and Inodrillia Bartsch, 1943 have an uncanny resemblance to Cerodrillia . Tippett (1995: 134–135) illustrates the radula of Viridrillia williami Bartsch, 1943 and Viridrillia hendersoni Bartsch, 1943 to demonstrate the more appropriate placement of the genus in Crassispirinae . Recently, most of the Crassispiriinae, including Viridrillia , have been placed in Pseudomelatomidae Morrison, 1965 (Bouchet et al., 2011) . Earlier, Sysoev, in Taylor et al. (1993: 164) listed Inodrillia as a crassispirine genus on the basis of its radula teeth. Inodrillia has most recently been provisionally placed in Horaiclavidae Bouchet, Kantor, Sysoev & Puillandre, 2011 (Bouchet et al., 2011) . Although very similar, Viridrillia has subtle morphological characteristics not seen in any of the known Cerodrillia : an anterior fasciole that lacks spiral ridges, the presence of spiral threads or grooves over the entire shell, not just on the shell base, and a protoconch with obsolete riblets that nonetheless leave a wrinkled look. The protoconch of Cerodrillia is always smooth.

Distribution. The genus Cerodrillia is the fourth most species rich among TWA Drilliidae . Cerodrillia is distributed throughout the TWA but most have so far been found to occur in the subtropical waters of the northern portion of this region: Gulf of Mexico, Florida and the Bahama Is. (see general approximate ranges of known species in Plates 35–36 ). C. brasiliensis and C. elegans inhabit southern subtropical waters (southern Brazil).

Figures

PLATE 35. Cerodrillia thea (Dall, 1884). Bahama Is., Florida Keys, E Florida and Cuba specimens. Bahama Is. Fig. 1: Bimini Is. (USNM 900139); Figs. 2, 4 – 5: Tenbay Beach, Eleuthera I. (author’s coll.); Fig. 3: Bimini Is. (H. G. Lee coll.). Florida Keys (Monroe Co.). Figs. 6 – 8: Tavernier Key (H. G. Lee coll.); Fig. 9: Boca Chica Key, Florida Keys (author’s coll.); Figs. 10 – 12: Key Largo (USNM 890154); Figs. 13 – 14: Harry Harris Park, Tavernier Key, Florida Keys (author’s coll.); Figs. 15 – 17: Middle Torch Key (E. Shuller coll.); Fig. 18: N shore, Content Keys (H. G. Lee coll.); Figs. 19 – 20: Little Torch Key (USNM 900134); Figs. 21 – 22: Long Key (USNM 900136); Fig. 23: Boot Key, Marathon (EFG 11547). E Florida. Fig. 24: off Stiltsville, Miami, Miami-Dade Co. (USNM 900141); Fig. 25: Peanut I., Palm Beach Co. (H. G. Lee coll.). Cuba. Figs. 27 – 29: Hicacos Peninsula, Matanzas Prov. (ANSP 157724); Figs. 30 – 31: Cardenas Bay, Matanzas Prov. (USNM 411327).

PLATE 36. Cerodrillia yucatecana, new species. Figs. 1 – 3: holotype, off Contoy Light, Quintana Roo, Mexico (USNM 900116). 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. Fig. 4: paratype, Gulf of Mexico (USNM 900133), ventral view.