Cerion uva knipensis, new subspecies

  Type locality: (CbI7b) valley between Seroes Palomba and Baha Hoendoe, northern Curaçao.

Distribution: Curaçao; north of Seroe Grandi; both on limestone (C14-20), and in the higher hills on outcrops of the older rocks (CbI6, 17, 20). Similar in habits to uva, but burrowing more deeply in the talus of the older rocks. 429 adults collected.

This subspecies (Plate XIX) has higher whorls than typical uva. In the statistical study, the data for each lot were ar­ranged in three tables, with vertical columns for the whorl classes and transverse rows to indicate, in the different tables, the altitude, major diameter and index classes (cf. Table XI). This brought out the fact that, in C. utva uva, the altitude was very closely correlated with the number of whorls, but did not vary greatly with the diameter. Although considerable indi­vidual variation is present, the means show that C. uva knipen­sis (Table XIII) quite consistently has a greater altitude for the same number of whorls. The only lots of C. uva uva that tend to approach them, in this particular, are the very large shells from near Landhuis Hato (C11c, d, and C12a).

The typical specimens (fig. xix-F5) of this subspecies come from the wooded valleys of the higher hills, in the region of the older rocks. These shells are very large, and have a pecul­iar, porcellanous texture, which contrasts rather markedly with the chalky surface of most of the shells from the lime­stone outcrops. In addition, a few specimens show a slight tendency to reduce the sculpture, although most of them are quite as heavily sculptured as typical C. uva uva.

C. uva knipensis (Table XIII) shows the same type of ecological variation discussed in C. uva uva (Table XII). Many of the animals mature with a smaller number of whorls than do any of the typical subspecies. In addition, there is a similar amount of variation in the major diameter. The smallest specimens may be called form djerimensis, new (fig. xix-A1), with the top of the shore cliffs near Plaja Djerimi (017 c) as the type locality.

Table XIII. Mean and Extreme Dimensions of Gerion uva knipensis

Comparison of Stations

Place   Nos.    Whorls               Altitude              Index              Maj. Diam.

C18         24   11.2(10.5-12.0)   21.3(18.3-23.6)    49(44-55)      10.5(9.5-11.2)

Cb17, 20  72   11.9(11.0-13.0)   24.0(20.5-27.8)a  43(34-50)      10.3(9.3-11.2)

Cb16       16   11.4(11.0-12.5)   22.8(20.9-26.1)    45(37-49)      10.1(9.6-10.6)

C20         31   11.5(10.5-12.5)   22.5(19.8-25.6)    45(37-51)      10.0(9.1-10.7)

C16         34   11.2(10.5-12.5)   21.7(19.4-25.6)    46(39-51)      10.0(9.0-10.5)

C17a       55   11.1(10.5-12.5)   21.2(18.8-24.8)    47(42-53)        9.9(9.1-11.0)

C15, 17a  81   11.1(10.0-12.5)   21.2(18.3-24.2)    46(39-53)        9.7(8.7-10.6)

C19         41   10.5( 9.5-11.5)    20.2(17.6-22.7)    48(44-55)        9.6(8.8-10.5)

C14         54   10.5( 9.5-12.0)    20.0(17.2-24.3)    47(37-53)        9.4(8.6-10.6)

C17bc      21   10.5( 9.5-11.5)    19.7(17.2-24.3)    46(39-53)        9.1(8.1-10.1)

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Total      429   11.1( 9.5-13.0)    21.5(17.2-27.8)    46(34-55)        9.9(8.1-11.2)

a Bimodal: 22.4 and 25.1.