Polygona lactea ( Matthews-Cascon, Matthews & Rocha, 1991 )

Lyons, William G. & Snyder, Martin Avery, 2019, Fasciolariidae (Gastropoda: Neogastropoda) of French Guiana and nearby regions, with descriptions of two new species and comments on marine zoogeography of northeastern South America, Zootaxa 4585 (2), pp. 239-268 : 260-261

Polygona lactea ( Matthews-Cascon, Matthews & Rocha, 1991)

( Figures 29–38 )

Latirus lacteum Matthews-Cascon et al., 1991: 1 –6, figs. 1–4; Snyder, 2003: 123; Mallard & Robin, 2005: 18 ( Brazil); Pimenta et al., 2014: 69, 90, figs. 19 (holotype figured in two views). Polygona lactea: Vermeij & Snyder, 2006: 418 –420, fig. 3R.

Types. Holotype: dd, 27 mm, off Pará , Brazil, 01°32’05”N, 47°24’05”W, 63 m, MNRJ 6201 . Paratypes: 2-dd, 18 and 32 mm, CMPHRM 688B and 1031B.

Material examined. French Guiana —2-dd, 25.5 and 29.5 mm, GUYANE sta. CP 4352, 05°13.9’N, 51°41.7’W, 60 m, 28 Jul 2014.

Remarks. Latirus lacteum Matthews-Cascon et al., 1991 , was introduced for five specimens dredged from coralline algae substrates off Pará and Amapá, Brazil. The description and figures resemble some specimens of P. bernadensis from French Guiana. We could not obtain specimens for comparison but obtained photographs of the holotype ( Figs. 29–30 ) and two paratypes ( Figs. 31–34 ). The paratypes are long-dead shells bearing polychaete tubes, foraminifera, and other encrustations, but the holotype, a shiny white shell, is fresh and in good condition except for an eroded protoconch.

Specimens we include here as P. lactea are two empty white shells with broken lips and drill holes ( Figs. 35–38 ); white seems to have been their original color and not a result of fading. Protoconch and teleoconch morphologies of the shells resemble those of P. bernadensis but the protoconchs are slightly smaller and the revolving cords of the spire are narrower than those of the latter species; many cords of P. lactea are separated by single, finer threads in their interspaces. The net effect is of a shell that more resembles the original figures of P. lactea than they do shells of P. bernadensis .

Although P. lactea was listed by Mallard and Robin (2005), it was not included in the compendium by Mallard and Robin (2017). Very few specimens are known, and the original specimens seem to have been immature and in less than optimal condition. Perhaps fresher mature specimens could enable better understanding of this poorly known species.

Figures

FIGURES 17–38. Guianas Peristerniinae. 17–21. Lamellilatirus corrugatus n. sp. 17–19. Holotype, 30.5 mm, CP4381, 06°31’N, 52°26’W, depth 114–118 m, MNHN IM-2013-56529. 20–21. Paratype, 23.8 mm, CP 4380, MNHN IM-2012-20355; ANSP 473537. 22–26. Lamellilatirus boucheti n. sp., 22–24. Holotype, 23.1 mm, CP4381, 06°31’N, 52°26’W, depth 114–118 m, IM-2013-56530. 25–26. Paratype, 19.1 mm, same date as holotype, IM-2013-56531; ANSP 473538. 27–28. Polygona bernadensis (Bullock, 1974), 46.4 mm, CP 4402, 06˚18’N, 52.˚13.3’W, depth 95–97 m, MNHN IM-2013-56853. 29–38. Polygona lactea (Matthews-Cascon et al., 1991). 29–30. Holotype, 27 x 11 mm, Almirante Saldanha, sta. 1767, off Pará, Brazil, 01°32’05”N, 47°24’05”W, depth 63 m, MNRJ 6201. 31–32. Paratype, 18 x 8 mm, same data as holotype, CMPHRM- 668B. 33–34. Paratype, 32 x 14 mm, Almirante Saldanha sta. 2441, off Pará, 01°46’N, 47°14’W, depth not stated, CMPHRM- 1031B. 35–38. 25.5 and 29.5 mm, CP4352, 05°13.9’N, 51°41.7’W, depth 60 m, MNHN IM-2014-6078.