Tidesmus

Shear, William A. & Shelley, Rowland M., 2007, The milliped genus Tidesmus Chamberlin, 1943 (Polydesmida: Macrosternodesmidae), Zootaxa 1656, pp. 51-68 : 64-66

" Tidesmus " hubbsi Chamberlin, 1943

Figs. 22–24 .

Tidesmus hubbsi Chamberlin, 1943:36 , fig. 4. Chamberlin and Hoffman, 1958:74.

Type specimens: Presently lost. "Several females" were collected by C. L. and E. L. Hubbs, 25 June 1942, from an unnamed cave in Cave Valley, northern Lincoln Co., Nevada.

Remark s. The types, the only specimens mentioned by Chamberlin (1943), were retained in his personal collection that was transferred to the National Museum of Natural History, Smithsonian Institution, Washington, DC, in 1972, five years after his death. However, the specimens are not in the USNM type collection, and T. hubbsi is not on the institution's list of myriapod types; they appear to have been lost sometime after 1943. A search for them in the general collection was unsuccessful.

According to Chamberlin (1943), the types of T. hubbsi were 5 mm long and 0.43 mm wide, which is substantially smaller than those of T. episcopus . As Loomis (1960) correctly surmised, it is unlikely that the species are congeneric with this substantial size difference and the geographical and ecological lacunae between them. Gretchen Baker of the US National Park Service has visited Cave Valley Cave on two occasions in the past two years (2006, 2007) to try to collect males of this species, but only a few females were found; one is illustrated in Figs. 22–24 . We defer designating one of these females as the neotype for a male that will resolve the true identity of the species.

FIG.URE 25. Southwestern United States and northwestern Mexico, showing localities of Tidesmus spp. Dots, T. episcopus ; Stars, T. variabilis ; Squares, T. torreyanus ; Star in dot, T. hastingsus ; Asterisk, " T. " hubbsi ; Question marks, samples tentatively assigned to Tidesmus .

Chamberlin (1943) provided no reason for including hubbsi in Tidesmus , and since only females were available, it could not have been based on gonopodal features. We surmise that it was the shared presence of clavate dorsal setae, which are exhibited by many small polydesmidans. The type locality of hubbsi is far removed from the closest authentic site of Tidesmus , that of T. variabilis in Prescott, Yavapai Co., Arizona, around 320 mi (512 km) to the south-southeast, and congeneric status is unlikely. Other minute-bodied macrosternodesmids, belonging to undiagnosed genera, occur in caves in Great Basin National Park, White Pine Co., Nevada, only some 50 mi (80 km) to the northeast, as well as in the Arizona Strip, the region between the Grand Canyon and the northern border of the state, and hubbsi is more likely to be congeneric with these more proximate forms. Consequently, we remove hubbsi from Tidesmus and leave it unassigned.

? Tidesmus spp.

In addition to the previous species, all based on samples with identifiable adult males, unidentifiable samples without males exist from within the generic distribution that plausibly are referable to Tidesmus . Specific identities cannot be determined at present, so we cite them below for future reference. The VMNH samples from Arizona were in a jar of " Oodedesmus " variabilis labeled " PARATYPES," but they were not so designated by Loomis (1960) in the original description and hence do not hold this status (Article 72.4.6 of the Code).

CALIFORNIA: Riverside Co., off Temescal Canyon Rd. S of Corona, m (gonopods lost), 1 November 1925, "Hardy" (VMNH); and 5 mi (8 km) S Palm Desert, along Deep Cr. in Deep Canyon Preserve, f, 18 January 1985, C. R. Nelson, R. W. Baumann (NCSM).

ARIZONA: Gila Co., Barber Pole Cave ca. 10 mi (16 km) NE Payson, Tonto National Forest, f (18 segs.), 19 June 1965, D. R. Davis, G. T. Lane (FSCA). Pima Co. , ca. 20–30 mi (32–48 km) NE Tucson, Santa Catalina Mts. , juv., April 1921, H. F. Loomis (VMNH); and ca. 40 mi (64 km) SW Tucson, Baboquivari Mts., m (gonopods lost), 21 November 1923, H. F. Loomis (VMNH).

Remarks. The California specimens could plausibly be either T. episcopus or T. torreyanus ; the site south of Palm Desert is roughly equidistant (75 mi [120 km]) from the type localities of both T. torreyanus and T. dentatus , lying northeast of the former and southeast of the latter. The female from Barber Pole Cave, Arizona, has only 18 segments and may not be applicable to Tidesmus , in which all authentic females have 20 segments; an undescribed genus whose species possess 18 segments has been found in at least one Utah cave.

Figures

FIGURES 22 – 24. “ Tidesmus ” hubbsi. 22. Anterior end, dorsal view. 23. Midbody segment, dorsal view. 24. Epiproct, dorsal view.