Spirobolinae Bollman, 1893

Shelley, Rowland M. & Floyd, Samuel D., 2014, Expanded concept of the milliped family Spirobolidae Diplopoda: Spirobolida: Spirobolidea): Proposals of Aztecolini n. tribe and Floridobolinae / ini and Tylobolini n. stats.; (re) descriptions of Floridobolus and F. penneri, both Causey, 1957, and F. orini n. sp.; hypotheses on origins and affinities, Insecta Mundi 2014 (357), pp. 1-50 : 25

Subfamily Spirobolinae Bollman, 1893

Spirobolinae Bollman, 1893:156 . Jeekel, 1971:210 (list). Kevan, 1983:2962.

Type-genus. Spirobolus Brandt, 1833 .

Diagnosis. Body form rounded/cylindrical ( Fig. 33 ). Anterior gonopod sternum with variably broad medial lobe substantially separating coxal endites; telopodites apically uncinate. Posterior gonopod telopodite with variably long, lobate prefemoral process overhung and enveloped to varying degrees by acropodite. Latter thin and laminate, variably cupulate with cavity/depression of varying depth; either short and marginally irregular with indentations, lobes, and spiniform projections, or long with smoothly curvilinear margins.

Components. Two tribes: Spirobolini Bollman, 1893 , and Aztecolini , new tribe.

Distribution ( Fig. 27 ). Four regions including the entire familial areas in Asia and eastern North America along with the point locality in Minnesota. Spirobolinae occur syntopically with Floridobolinae / Floridobolini in their Floridian locations and while absent from western North America and Guatemala, they partly overlap Floridobolinae / Tylobolini in central Mexico, occurring from northern Nuevo León to central Jalisco and northern Guanajuato ( Fig. 28 ). The distance between Taiwan and Jalisco, the closest New World locality, is approximately 13,315 km (8,322 mi), one of the greatest subfamilial lacunas in the Diplopoda. Distances between areas in Mexico and the US are as cited in Table 3.

Origin. Substantial evolutionary changes had to take place for Floridobolinae / Tylobolini / Hiltonius to evolve into Spirobolinae / Aztecolini / Aztecolus , so this divergence logically took longer than that which yielded Tylobolini . We arbitrarily allow 5 my for these changes and assign an age of <296 my to Spirobolinae , which likely evolved in Mexico before Tylobolus arose in California and perhaps before Hiltonius even reached this state.

Figures

Figure 27. Distribution of Spirobolinae.

Figure 28. Distribution of Aztecolini plotted against Cretaceous land patterns; submerged, marine Florida terrane and approximate maximal dimensions of the Western Interior Seaway in light blue. Ap, Appalachia. AZ, Aztecolus. C, Chicobolus. L, Laramidia. SA, Presumptive Source Area in the “northern Mexican Highlands.” The area encircled with brown squares is that of Tylobolini/Hiltonius/H. carpinus; the area where Aztecolus and Tylobolini/Hiltonius overlap is plausibly the source area.

Figure 33. Ring profiles in Spirobolidae. Left two rings, transversely ovoid profile shown by Floridobolinae/ Floridobolini. Right two rings, rounded profile demonstrated by Floridobolinae/Tylobolini and Spirobolinae. Photo courtesy of O. McMonigle.