PROC. BIOL. SOC. WASH. 95(2), 1982, pp. 256-264 A NEW SPECIES OF OREOHELICID LAND SNAIL FROM THE SAN AGUSTIN PLAINS, NEW MEXICO Celinda R. Crews and Artie L. Metcalf Abstract. — A new species of pulmonale land snail, Oreohelix litoralis, is de-scribed from populations inhabiting wave cut cliffs in the southern part of the San Agustin Plains, west-central New Mexico. Taxonomic evaluation is based on qualitative and quantitative characters of shell and genital structures. A rede-scription of Oreohelix magdalenae Pilsbry is provided, since it is considered to be closely related to Oreohelix litoralis. Both species are members of the Oreo-helix metcalfei Cockerell complex within the Oreohelix yavapai Pilsbry group. Most of the basic taxonomic work on the genus Oreohelix in New Mexico was done by H. A. Pilsbry and J. H. Ferris s, culminating in Pilsbry' s (1939) mono-graphic treatment of known species. A number of New Mexican oreohelicids were assigned to the wide-ranging Oreohelix yavapai Pilsbry, 1905, group. Taxa occurring in the Black Range and peripheral mountains in south-central New Mexico were ascribed to the Oreohelix metcalfei Cockerell, 1905, complex. Met-calf (1974) discussed and referred several species to this complex, including Or-eohelix magdalenae, Pilsbry, 1939, as a northeastern derivative. The new species described below is judged to be a northern derivative of this complex and to be closely related to Oreohelix magdalenae . Oreohelix litoralis, new species Figs. lA, B, C; 2A; 3A Description of shell of holotype (from Locality 6). — Shell slightly depressed, convex dorsally and ventrally; spire forming angle of 118°; 16.4 mm in diameter and 9.7 mm in height; upper lip descending only slightly; angular peripherally with angularity at about mid-height of body whorl; first 2 whorls keeled; aperture slightly ovate horizontally, 7.7 mm wide and 6.2 mm high; aperture oriented at angle of 54° to vertical axis of shell; umbilicus open, not contracting rapidly within, 3.9 mm wide, contained 4.21 times in diameter; sutures moderately im-pressed; 5.10 whorls; dorsal surface generally smooth, with sculpture limited to growth lines, weak and irregularly spaced on early whorls, becoming stronger on body whorl; ventral surface smooth with only low growth lines (no spiral striae or Hrae); earliest 2.25 whorls of dorsal surface uniformly cinnamon brown, grading to grayish brown mottling on a whitish background by whorl 3 with mottled pattern extending to body whorl; thin brown band appears at 2.25 whorls, ex-tending to body whorl; this band situated approximately one-third whorl-width inward from suture on earlier whorls and approximately one-third whorl-width above angulation on body whorl; ventral surface with grayish-brown mottling mainly descending ("bleeding") from thin brown band present on body whorl immediately beneath angulation. Variation in shells. — Variation in shell measurements and proportions for 20
BioStor
