Hiltonius mexicanus (De Saussure 1859)

Hiltonius mexicanus (Saussure)
Julus mexicanus Saussure, Linnaea Ent., vol. 13, p. 332. 1859.
Julus mexicanus Saussure, Mem. Soc. Phys. Hist. Nat. Geneve, vol. 15, pt. 2, p.
366 [erroneously numbered " 566"], fig. 34. 1860. Spirobolus mexicanus, Saussure and Humbert, Mission scientifique au Mexique,
Myriapodes, p. 177. 1872. Spirobolus mexicanus, Pocock, Biol. Centr.-Amer., Diplopoda, p. 81. 1908. Spirobolus mexicanus, Carl, Rev. Suisse Zool., vol. 27, p. 402, figs. 40-42. 1919. Eurelus tancitarus Chamberlin, Ent. News, vol. 52, p. 255, figs. 5-7. 1941.
New synonymy. Hiltonius federalis Chamberlin, Bull. Univ. Utah, biol. ser., vol. 8, no. 3, p. 22,
fig. 38. 1943. New synonymy. Hiltonius michoacanus Chamberlin, ibid., p. 23, figs. 39^1. New synonymy. Hiltonius tancitarus Chamberlin, ibid., p. 23. Hiltonius veracruzanus Chamberlin, ibid., p. 24, figs. 42-43. New synonymy.
Nomendatorial Considerations. — I have seen the types of mexicanus, tancitarus, federalis, and michoacanus and specimens of veracrusanus Usted by ChamberHn at the time of the original description of that species. I consider them all conspecific.
Diagnosis. — Distinguished from other species of the genus by characters of the male and female genitalia as given in the key. Differs from carpinus, with v^^hich it is sympatric, also in the sharper lateral ends of the collum, the deeper emarginations of the anterior margins of the paranota of the collum, and the usually more rounded ventrolateral corners of the second segment, the productions of w^hich are generally not limited to the anterior corner.^
Description. — L of males 35-58 mm. (49.0), of females 46-67 mm. (55.5) ; W of males 4.3-6.4 mm. (5.66), of females 5.7-7.8 mm. (6.86) ; L/W of males 8.1-9.3 (8.6), of females 7.3-8.8 (8.1). Segments 40-49 (42.6).
Eyes per patch 21-36 (27.9). Clypeal setae 6-9 (8.0); labral setae 13-20 (15.4). Stipital setae of gnathochilarium 5-9 (7.0) per stipes.
Lateral ends of collum subacute; anterior margins of paranota of collum eniarginate below level of eye patches, the emarginations often very deep. Sec-
5 With the aid of a grant from the American Philosophical Society I was able to spend the summer of 1959 in Mexico. Series of both Hiltonitts mexicanus and Hiltonius carpinus were collected and are now being studied. Further information concerning these species will be published in the future, but one unexpected fact should be mentioned in this monograph. The two species differ markedly in color, mexicanus being banded with vivid red and black while carpinus is banded with duller red and yellow. ond segment much exceeding ends of collum but its productions usually not limited to anterior corner, often consisting of large rounded knobs extending over entire ventrolateral portions of segment.
Tergal striae usually not very strong, ending about midway between pleural sutures and repugnatorial pores.
Legs short, usually not reaching sides of body when held horizontally.
Anterior telopodites of gonopods distinctly uncinate distally. Posterior coxae sometimes greatly reduced, the reduction generally greatest in region of cephalic surface. Posterior telopodite decidedly compressed, without numerous small spines on its distal surface; prefemoral portion distinct but only partially set off from tibiotarsal portion on cephalic surface. Elongate opening of seminal receptacle located on mesal margin just proximal to distal end of telopodite; opening bordered by thin sclerotized lips. Telopodite usually bearing small hook-like distal process, this often with a small serrate flange.
Cyphopod with shallow depression in disc of lateral surface ; lateral suture relatively straight or gently sinuate, never with loop in discal depression.