The Jamaican land snail genera Geoscala and Simplicervix (Pulmonata: Urocoptidae)

Submitted by admin on Sun, 20/11/2011 18:55
C. R. C. PAUL
(1982)
Volume
31
Part
2
Page from
101

The Jamaican urocoptid genera Geoscala Pilsbry & Vanatta 1898 and Simplicervix Pilsbry 1903 are revised and their anatomy described for the first time. Geoscala has a shell with large white ribs, often split into two series above and below the periphery, and with 9—15 occurring on the penultimate whorl. Internally, the genitalia are completely separate from the right ocular retractor. Radula formula is 4:2:1:2:4; the central is weakly bilobed; the laterals enormous with elongate, symmetrical mesocones. Simplicervix has a shell with fine continuous ribs; 55—80 on the penultimate whorl. The right ocular retractor is attached to the vagina. Radula formula is 5:2:1:2:5; the central is weakly trilobed; the laterals proportionately broader and assymetrical. Both genera have small (5—11 mm) shells with an originally perforate apex which are decollate as adults and uncoil before the aperture; a globular spermatheca; a separate penial retractor muscle; both ocular retractors attached to the pharyngeal retractor; a radula with two enormous laterals and distinct marginals and are therefore assigned to the sub-family Apominae Paul 1982.
      G. seminuda has deep sutures and an obsolete lower series of ribs, G. robertsi shallow sutures and both series of ribs, while G. costulata is smaller and has continuous ribs. G. seminuda and G. robertsi inhabit dry limestone forest along the south and north coasts, respectively. G. costulata and S. inornata occur in wet limestone forest of the central highlands. Neither S. humilis nor S. simplex has been rediscovered since their original description. S. humilis is illustrated for the first time.