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BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 46(3)
Measurements of the holotype and eleven paratypes are given in Table 7.
Anatomy. The head-foot is grayish-black when alive. The mantle in preservatives is uniformly dark gray. The live animal did not exude a distinct odor when handled.
Reproductive system (Figs. 52-53). Two specimens were dissected. The genital atrium is very short and almost non-distinguishable. The penis is short and stocky, almost ovate-shaped, and 6 mm long. The interior has a long verge that extends nearly the length of the cavity (Fig. 53). The inner wall of penis has a series of folds around the middle and several smaller longitudinal folds below. The penis retractor muscle is slender, 13 mm long. It originating on the middle of inner wall of lung midway behind the mantle collar and inserting on the base of the epiphallus where it forms a narrow sheath around the lower fourth of the epiphallus. The epiphallus is short and stout, and is slightly longer than the penis. Its interior has three longitudinal folds lying opposite a flattened area. The flagellum is stout and tapers abruptly to a point. It is 17 mm long, slightly longer than the combined length of the penis + epiphallus. The interior of the flagellum has four longitudinal folds. The lower vagina is 20 mm long and slender; with four dart-sacs, of which ds, is the largest; ds2 the next largest; ds3 and ds4 are subequal in size. The middle vagina is surrounded by a four lobed dart-gland that is widely separated from the dart-sacs. The free vagina is not apparent. The spermatheca + duct is moderately short; about 37 mm long and about the same length as the uterus. The spermathecal duct bears a short caecum that is located at about 0.60 of the distance from the base of the duct. The caecum is about equal in length of duct below the spermatheca and its origin. The spermatheca is elongate and almost elliptical in shape.
Type locality. Chihuahua, Sierra Victorino, 17
km west of Nueva Majalca (2847.4'N, 10627.7'W) 1900-2000 m alt. Holotype: UF 317164; collected 6 August, 2003 by Fred G. Thompson and Elizabeth L Mihalcik. Paratypes: (UF 317160 (15), 317161 (4),ITCV (10); same data as the holotype.
Distribution. Known only from the type locality.
Ecology. This species was found on a steep slope in an open sub-mesic oak and juniper forest. Snails were found among dead leaves on the forest floor. It had rained during the previous night, and live specimens were not in aestivation. Apparently this species burrows in the ground during dormancy, because granite ledges near by had no concentrations of dead shells.
Remarks. Humboldtiana oberon is closely related to H. titania as is indicated by similar shell features and the reproductive anatomy. Although they appear similar, the two differ substantially in shell features, as well as anatomical structure that distinguish them as separate species.
Etymology. The species name oberon is from the Classical Literature, Shakespeare, Wm, 1594, A Mid Summer Night Dream. Oberon is the fairy king.
Species from the vicinity of Ciudad Chihuahua
Low mountain ranges and hills in this region are inhabited by Clydonacme. The two known species do not appear to be closely related to other members of the subgenus because of the relatively rugose embryonic shell sculpture. Only one is known anatomically. It differs from other species by having a long genital atrium, a moderately long and stout epiphallus, the penis retractor inserts at the base of the epiphallus, the flagellum is long and slender, the middle vagina is slightly extended, narrowly separating the dart-sacs from the dart-glands, and the spermathecal duct is very long.
Table 7. Humboldtiana oberon n. sp. Measurements in mm of the holotype (UF 317164) and 11 paratypes, UF 317160 (7) and UF 317161 (4). A paratype 38.0 mm wide is not included in the table because of a broken apex.
H W AW AH Whorls H/W AW/W AH/H AW/AH
Holotype 27.2 32.7 18.3 20.0 4.2 0.83 0.56 0.74 0.92
Paratypes
Min. 24.5 30.5 16.6 18.4 4.0 0.79 0.51 0.69 0.82
Max 29.5 34.2 18.3 21.9 4.2 0.88 0.58 0.81 0.97
Avg 26.69 32.04 17.48 20.08 4.12 0.83 0.55 0.75 0.87
SD 1.17 1.17 0.56 0.79 0.10 0.03 0.02 0.03 0.04