Hiltonius Chamberlin, 1918

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 : 23

Genus Hiltonius Chamberlin, 1918

Julus (Julus) (not Linnaeus) in part: Saussure, 1859:329; 1860:96.

Spirobolus (not Brandt) in part: Saussure and Humbert, 1872:74–75, 175.

Hiltonius Chamberlin, 1918b:166 ; 1943b:21; 1949:166. Loomis and Hoffman, 1951:51. Chamberlin and Hoffman, 1958:163. Hoffman and Keeton, 1960:15. Keeton, 1960a:97–99. Buckett, 1964:23. Loomis, 1966:25; 1968a:92; 1968b:392. Jeekel, 1971:199. Hoffman, 1980a:77; 1998b:64; 1999:41. Shelley, 2002a:98 .

Type-species. H. pulchrus Chamberlin, 1918 , by original designation.

Diagnosis. Generally stout, robust Tylobolini ; paraprocts usually slightly re-entrant, with or without marginal rims. Posterior gonopod acropodite usually with two variably distinct distal lobes, only slightly prolonged if any, not curving strongly dorsad or decurved and not imparting uncinate appearance to overall appendage.

Components. Ten nominal species, both extant and fossilized; one species is divided into two subspecies: H. mexicanus ( Saussure, 1859) ; H. hebes ( Bollman, 1887) ; H. reptans (Porat, 1888) ; H. australis (Grinnell, 1908) ; H. fossulifer (Pocock, 1908) ; H. pulchrus Chamberlin, 1918 ; H. mimus Chamberlin, 1941 ; H. erythropygus Chamberlin, 1943 ; H. carpinus carpinus Chamberlin, 1943 , and H. c. vulcan (Chamberlin, 1952); and H. flavocinctus Loomis, 1968 ( Keeton 1960a; Hoffman 1999; Shelley 2002 a , 2010).

Distribution ( Fig. 12 , black lines). Four segregated areas: southern California and adjacent Baja California Norte; southeastern Arizona; from southern Durango, Coahuila, and Nuevo León to Guerrero, Mexico; and the Guatamalan point locality. The distributions of Hiltonius and H. pulchrus extend from Ft. Tejon and the Santa Monica Mountains, Kern/Los Angeles cos., in northern metropolitan Los Angeles, to northern Baja California Norte and eastward to the vicinities of San Bernardino and Riverside.

Origin. Since H. carpinus occurs in southeastern Arizona, Guatemala, and the presumtive, central Mexican, familial source area, we believe it is the original, ancestral tylobolinine and arose <301 mya.

Remarks. While Hiltonius was dispersing to California and Guatemala, divergences and evolution continued in the source area and Floridobolini were spreading northeastward.

Figures

Figure 12. Distribution of Floridobolinae plotted against Cretaceous land patterns; submerged, marine Florida terrane and approximate maximal dimensions of the Western Interior Seaway in light blue. Ap, Appalachia. F, Floridobolus/Floridobolini. L, Laramidia. SA, Presumptive Source Area in the “northern Mexican Highlands.” Black lines and dot (delineated by the arrow), Hiltonius/Tylobolini. Red line, Tylobolus/Tylobolini. Green line and dot (in Florida), Floridobolus/Floridobolini. The area where Tylobolini/Hiltonius and Aztecolus overlap constitutes the presumptive source area.