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: 256] compared C. krousma with the holotype of Scalaria canephora [Natural History Museum, 2014: NHM 1906.10.23.2] from the Gulf of Oman, noting that C. krousma is much larger, with less angular whorls and a blunter, less conical protoconch. Scala proxima, from off Sumatra, is also similar but has spiral lirae below the suture, while Scala capitata, from off Tanzania, differs in shape

Distribution:

Durban Bay, South Africa [Kilburn, 1985: 254].

Habitat:

shallow water [Kilburn, 1985: 254].

Etymology:

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

Type Material:

Holotype: NM B6089/T2764. Paratypes, 1-22: NM B6088/T2765. for Cirsotrema krousma Kilburn, 1985 - Type Locality: Durban Bay, shallow dredgings, leg. B. J. Young.. [Kilburn, 1985: 254]
Holotype: NM B6089/T2764 [as Cirsotrema (Cirsotrema s.l.) krousma Kilburn, 1985:] - Type Locality: Durban Bay, South Africa, shallow dredgings.. [Brown & Neville, 2015: 92]