Agladrillia Woodring, 1928

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: 17

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Agladrillia Woodring, 1928


Genus Agladrillia Woodring, 1928 

Type species by original designation, Agladrillia callothyra Woodring, 1928  , Miocene [now considered Pliocene (from Donovan, 1998)], Bowden, Jamaica.

Diagnosis. According to Woodring (1928: 157), shell small, moderately slender; whorls moderately convex with a varix about ½-turn (“some distance”) from lip edge. Protoconch of 2 smooth whorls. Axial sculpture of narrow ribs that stretch from suture-to-suture, arcuate and reduced as “obscure prologations” in the sulcus, and spiral grooves and threads that may be reduced or obsolete on the axial ribs. Aperture long and narrow; outer lip with a relatively deep stromboid notch anteriorly and a deep U-shaped anal sinus posteriorly, near suture. Anterior canal moderately long, strongly constricted, deep, twisted to the right viewed ventrally and bent slightly dorsally, with an asymmetrical, deep notch at its tip. Inner lip detached; parietal wall with a heavy callus.

Key characteristics. The combination of the following characteristics separate Agladrillia  from all other TWA Drilliidae  :

1. Shell sculpture of widely spaced narrow ribs that run from suture-to-suture, lower and recurved in sulcus, and of deep spiral grooves that are diminished or obsolete on rib crests;

2. Varix hump-like, positioned ½-turn from edge of outer lip;

3. Ribs obsolete on dorsum of last whorl, except in sulcus;

4. Anterior canal strongly constricted and deeply notched at its end; and

5. Protoconch of approximately 1 ½– 1 ¾ mostly smooth whorls.

Similar genera. Two other TWA genera also have deep spiral grooves. Calliclava McLean, 1971  differs in possessing a carinate, not smooth protoconch. Clathrodrillia Dall, 1918  has a smooth protoconch but differs in having a tapered rather than a “pinched” anterior canal, and a varix about ⅓-turn from the edge of the outer lip, not ½-turn as in Agladrillia  .

Distribution. Agladrillia  has been reported from northern South America ( Colombia to French Guiana).