Cirsotrema krousma

Description:

Dimensions range from 5.7 mm - 10.5 mm high and 2.1 mm wide.
Width to height ratio: 0.37:1 ~ 0.2:1

Shell: narrowly acuminate; minute to small. Exterior colour pale to light orange-yellow, costae white ribs. About 11 whorls, strongly convex; protoconch conical with ~3 whorls smooth, convex; teleoconch with ~8 whorls strongly convex. Suture deep. Umbilicate: closed or forming a slight, fenestrate chink. Approximately 12 - 18 costae on the body whorl. Costae are prosocline, strong and regular, rather cord-like. Costae not reflexed. Intercostal spaces well developed, subequal in width to their intervals. Interstices with approximately 5 - 9 spiral striae per whorl. Base with fine, irregular spiral threads. Columella reflexed and adnate. Fasciole distinct, base flattened. Aperture ovate; peristome fairly thin.

Kilburn [1985] details that C. krousma closely resembles Scala canephora Melvill, 1906, but compared with the holotype of that (BM(NH) 1906. 10232) from the Gulf of Oman, is much larger, with less angular whorls and a blunter, less conical protoconch. Scala proxima Thiele, 1925, from off Sumatra, also appears similar but is spirally lirate below the suture. Scala capitata Thiele, 1925, from off Tanzania, differs in shape.

Distribution:

Durban Bay, South Africa

Habitat:

shallow water

Etymology:

Greek, krousma = a tune produced by a harp., [Greek] krousma = a tune produced by a harp

Type Material:

Holotype, NM B6089/T2764, Durban Bay, shallow dredgings, leg. B. J. Young. Paratypes, 1-22, NM B6088/T2765. for Cirsotrema krousma Kilburn, 1985. [Kilburn, R.N, 1985]
Holotype: NM B6089/T2764 [as Cirsotrema (Cirsotrema s.l.) krousma Kilburn, 1985:] - Type Locality: Durban Bay, South Africa, shallow dredgings.. [Brown, L. & Neville, B.D., 2015]