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BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 46(3)
Etymology. The species name balanites is from the Classical Greek, PaXavoc,, an acorn-like object, and alludes to the appearance of this species.
Humboldtiana corruga Thompson & Mejia, 2006
Humboldtiana corruga Thompson & Mejia, 2006; Nautilus, 120, p. 25.
Type locality. Chihuahua, 0.8 km south, 0.3 km west of Norogachi, (27 15' 53 N, 107 7 49" W), 2280 m alt.. Holotype: UF 358872; collected by Omar Mejia, 25 August, 2003. Found in an open Pinus-Quercus woodland. Paratype: ITCV (1); same data as the holotype.
Distribution. Known only from the type loclality. Remarks. This recently described species is found at a locality near that of Humboldtiana balanites.
Gymnopallax n. subgen.
Type species. Humboldtiana cicatricosa new species. Referred species: Humboldtiana sylvania Thompson & Mejia, 2006.
Diagnosis. The shell is thin and fragile, and the apex is denuded of the periostracum even in small juveniles. The shell lacks granular sculpture. The embryonic whorls are raised and smooth. The color pattern consists of three poorly defined bands on a light brown background. They are interrupted by numerous dark brown streak and blotches. The outer wall of the lung is light gray and is mottled with numerous small darker gray spots (Fig. 41). A genital atrium is absent due to the abbreviated condition of lower genitalia. The penis has a large multi-lobed verge that extends the full length of the cavity. The flagellum is long. The vagina bears four dart-sacs, each of which has two exposed dart-bulbs. The dart-sacs are widely separated from the dart-gland ring. A free vagina is absent. The spermathecal duct is very long and lacks a caecum.
This subgenus is known only from a small area near Creel, Chihuahua.
Etymology. The name Gymnopallax (f) is from the Classical Greek yuu.vo<;, naked, and a youth.
The name refers to the denuded embryonic whorls.
Humboldtiana (Gymnopallax) cicatricosa n. sp.
Diagnosis. As for the subgenus.
Shell (Figs. 19-23). The small shell is up to about 28 mm wide. It is helicoid in shape, and is 0.90-0.94 times as high as wide. The shell is thin and fragile. Mature specimens have up to 3.5 whorls. The suture is deeply impressed, forming a narrow channel extending to the
aperture. The last quarter whorl descending to the aperture where the upper lip inserts on the lower band. The umbilicus is narrowly rimate. The embryonic shell has 1.7 large, elevated whorls. The first embryonic whorl is 4.9 mm wide transverse to the initial suture. The embryonic whorls are smooth. The apical periostracum is eroded so that by the time the shell approaches maturity the apex is denuded and is strongly pitted from erosion (Fig. 23). The postembryonic whorls are sculptured with coarse incremental threads and striation. Granular sculpture is absent. The color pattern is light, diaphanous brown with three dark brown bands that are interrupted by irregularly spaced alternating dark brown transverse bars and blotches. The upper and lower bands are about equally wide. The middle band is narrower. The aperture is obovate in shape; 0.83-0.86 times as wide as high with its greatest dimension along the vertical axis. The peristome is light gray in color. The interior of the aperture is hyaline brown and banded, and is glossy but rippled beneath the exterior sculpture. The aperture is prosocline, lying at an angle of 40 to shell axis (Fig. 20). The peristome inserts advanced between the middle and upper bands. It is weakly reflected along the dorsal and basal lip, and forms a narrow triangle along columellar lip to nearly occlude the umbilicus (Fig. 21).
Measurements of the holotype and three paratypes are given in Table 3.
Anatomy.The head-foot is dark gray in life. The outer wall of the lung is spotted with numerous small gray blotches (Fig. 41).
Reproductive system (Figs. 24-26). Two specimens were dissected. The holotype (Figs. 24, 25) appears to have been in an active breeding state, and the lower genitalia are greatly distended. A paratype (Fig. 26) also is figured. It appears to have been in an inactive sexual state. Measurements are given for the holotype first and the paratype second.
The genital atrium is abbreviated to the extent that it appears to be absent. The penis is very stout, about 10 mm long, and is constricted at the upper third. The inner wall is lined below the constriction with several very heavy longitudinal folds. Above the constriction the inner wall is lined with a few rather indistinct fleshy folds and pads. A very large verge extends nearly the full length of the penis cavity (Fig. 25). The verge ends in several digitiform and follicular processes forming a cluster of lobes. The penis retractor muscle originates on the center of inner wall of lung 3-4 mm behind mantle collar, and inserting on apex of penis where it forming a short sheath around the base of the epiphallus. The epiphallus is almost twice the length of the penis (19,13