Comprehensive DescriptionRead full entry
“Alatotrochus, gen. nov.
DIAGNOSIS.—Corallum cuneiform, with a rounded (free) base and prominent, costate thecal edge crests. Theca imperforate. Costae serrate, extending from calice to base; costae number twice that of septa. Four cycles of highly exsert septa. Pali absent; columella linear-papillose.
DISCUSSION.—Using my key to the turbinoliid genera (Cairns, 1989a:25-26), Alatotrochus would key to Platytrochus, the genus in which Moseley (1876) originally placed the type species. Alatotrochus does share several characters with Platytrochus, such as a cuneiform corallum with edge crests, a papillose columella, and the absence of pali. Alatotrochus differs from the type species, Platytrochus stokesi (Lea), however, in several significant characters. It has a much larger corallum, an additional cycle of septa, and twice as many costae as septa. Its costae are serrate and continuous from calice to base, whereas those of P. stokesi are discontinuous and granular. Finally, its columellar elements are large and linearly arranged, whereas those of Platytrochus are much smaller and grouped in an elliptical field or two rows.
Moseley (1881) later placed Platytrochus rubescens in the genus Sphenotrochus, which is not surprising given the similarity of Platytrochus and Sphenotrochus (see Cairns, 1989a: 38). Nonetheless, Alatotrochus differs from species of Sphenotrochus in having a papillose (not lamellar) columella; a larger corallum; serrate (not smooth) costae; and twice as many costae as septa.
Alatotrochus is monotypic.
ETYMOLOGY.—The name Alatotrochus (Latin alatus, meaning "winged" + trochus, a common coral suffix, literally meaning "wheel"), refers to the prominent edge crests of this genera that resemble wings. Gender: masculine.
TYPE SPECIES.—Platytrochus rubescens Moseley, 1876, here designated.
DISTRIBUTION.—Bungo Strait, off Kyushu; off Amami Oshima, Ryukyu Islands; 193-422; Banda Sea, 236 m; Pleistocene of Okinawa, Ryukyu Islands.”