THOMPSON: Humboldtiana from Chihuahua and Texas
79
the atrium is moderately slender and bears four dart-sacs. The first dart-sac, ds, is large and bulbous. The remaining dart-sacs, ds2, ds3 and ds4, are decreasingly smaller. The dart-gland are tightly appressed against the top of the dart-sacs. The free vagina is very short. The spermathecal duct + spermatheca is 61 mm long, is slightly longer than the uterus, and bears a caecum that diverges 16 mm below the end of the spermatheca. The caecum is short, less that half the length of the end of the spermathecal duct above its confluence.
Type Locality. Chihuahua, Sierra de la Catarina, highway pass ca. 12 km northeast of Ignacio Zaragoza (2946.0'N, 10737.8'W); 2250 m alt. Holotype: UF 320069; collected 13 August, 2003 by Fred G. Thompson. Paratypes: UF 317178 (10), UF 317179 (10), ITCV (10), same data as the holotype.
Distribution. Known only from the immediate vicinity of the type locality. Chihuahua, 21.6 km NE of Ignacio Zaragoza (2946.4'N, 10737.5'W), 2280 m alt. (UF 317176); 11 km NE of Ignacio Zaragoza (2946,0'N, 10738.2'W), 2320 m alt. (UF 317182).
Ecology. At the type locality snails were found in tallus along granite outcrops in a sparse submesic pinon-pine and oak forest with sparse clumps of bunch-grasses. Live specimens were aestivating on the underside of large boulders.
Remarks. In Humboldtiana regula the wavy transverse striations on the embryonic whorls are much finer than they are on the following species, and the granular sculpture on the first post-embryonic whorl is finer and not as dense. The shell is considerably smaller, it is darker colored and it bears more numerous white streaks. Humboldtiana regula is similar in its anatomy to the following species, and additional collections my reveal that the two are subspecifically related. Humboldtiana regala has an epiphallus that is about twice the length of the penis, and the dart-sac ds, is enlarged, whereas in the next species the epiphallus is
about 5-6 times the length of the penis and ds, is enlarged.
Etymology. The name regula is from the Latin regulus, a prince, alluding to the regal appearance of the shell.
Humboldtiana spectabile n. sp.
Diagnosis. The large shell is globose, shiny, and boldly banded. The embryonic whorls are sculptured with numerous wavy transverse striations. The first postembryonic whorl is densely sculptured with minute granulation overlaying radial striations. The genital atrium is very shot; almost non-existent. The penis is short, stout, and has a short verge. The stout epiphallus is 5-6 times a long as the penis. The penis retractor muscle forms a sheath around the lower third of the epiphallus. The flagellum is short, less the length of the epiphallus. The lower vagina is long and slender. The dart-sacs are sub-equal in size; ds, is the largest; ds3 is the smallest. The dart-glands are juxtaposed against dart-sacs. The free vagina is very short.
Shell (Figs. 36-39). The shell is moderately large, about 32-35 mm wide. It is sub-globose, 0.86-0.96 times as high as wide. The periostracum is shiny, and is colored light brown and bears three bold chestnut-colored bands. The ground color and the bands are interrupted with occasional white streaks. The lower band usually is the widest. The interior of the aperture has a whitish tinge and is banded. The umbilicus is obliquely perforate (Fig. 39). Mature shells have 4.0-4.2 whorls. The suture is deeply impressed. The embryonic shell is raised and consists of 1.5 whorls that are crossed by minute wavy striation. The following complete post-embryonic whorl is densely sculptured with minute granules between and overlying the growth wrinkles and striation. Subsequent whorls lack granular sculpture and are crossed with fine incremental stria-
Table 4. Humboldtiana regula n. sp. Measurements in mm for the holotype (UF 320069) and 16 paratypes (UF 317178/7; UF 317179/9).
 H W AW AH Whorls II/W AW/W AH/H AW/AH
Holotype 28.0 30.1 16.1 20.8 4.2 0.93 0.54 0.74 0.77
Paratypes 
Min 25.0 28.7 15.2 18.5 3.8 0.83 0.52 0.60 0.77
Max 29.1 33.1 20.4 22.6 4.2 1.00 0.58 0.80 0.98
Avg 27.16 30.18 16.53 20.12 4.0 0.90 0.55 0.75 0.83
SD 1.14 1.16 1.23 0.95 0.12 0.04 0.03 0.04 0.05