Tylobolus castaneus Chamberlin 1918

Tylobolus castaneus Chamberlin
Tylobolus castaneus Chamberlin, Proc. Biol. Soc. Washington, vol. 31, p. 166.
1918. Auxobolus castaneus Chamberlin, Journ. Washington Acad. Sci., vol. 39, p. 163.
1949. Auxobolus discipidus Chamberlin, ibid., p. 165, figs. 3-4. New synonymy. Auxobolus jriantus Chamberlin, ibid., p. 165, figs. 8-9. New sjmonymy. ? Axobolus [sic] ergus. Causey, Pan-Pacific Ent., vol. 30, p. 226. 1954. ? Auxobolus ergus, Causey, Proc. Biol. Soc. Washington, vol. 68, p. 88. 1955. Auxobolus castaneus, Chamberlin and Hoffman, U. S. Nat. Mus. Bull., no. 212,
p. 160. 1958. Auxobolus discipulus, Chamberlin and Hoffman, ibid. Auxobolus friantus, Chamberlin and Hoffman, ibid.
Nomenclatorial Considerations. — I have seen type material of all three of the names listed above. The holotype of castaneus is an immature male and thus does not show full development of the leg modifications typical of adults of the species treated here. I have compared it with immature males of most of the species of the genus and it agrees in every way with those of the form here designated castaneus.
Diagnosis. — The unusual modifications of both the pregenital and postgenital legs of the males are found only in this species. These characters make this the easiest species of the genus to recognize because study of the gonopods is not necessary for identification.
Description. — L of males 54-77 mm. (68.7), of females 46-92 mm. (65.8) ; W of males 5.3-9.6 mm. (7.14), of females 5.0-9.9 mm. (7.10) ; L/W of males 8.2-10.8 (9.8), of females 8.6-10.3 (9.2). Segments 48-54 (50.5).
Eyes per patch 30-48 (39.6). Clypeal setae 8-12 (9.3) ; labral setae 12-20 (14.6). Stipital setae of gnathochilarium 5-10 (7.7) per stipes.
Anal lips usually moderately distinct.
Coxae of 3rd male legs produced, forming subcylindrical, distally flattened lobes, these diagnostic of the species. Coxae of male legs 4—7 similar to those of other species but not as compressed, their ends broader. Podomeres of pregenital legs of male highly modified; 2nd and 3rd segments of legs 3-7 with prominent large swollen areas, those of 2nd segments limited to distal portion of ventral surfaces, those of 3rd segments larger and covering most of ventral surfaces; 4th and 5th podomeres not greatly modified. Second and 3rd segments of postgenital legs with ventral pads, those of 3rd segments on prominent projecting lobes. Claws of 1st and 2nd legs longer than last podomeres, those of legs 3-7 shorter, those of postgenital legs often about as long as last podomeres. Coxae of 3rd legs of females each usually with 2 or fewer ventral setae.
Gonopods like those described under the name ergus above.
Distal lobe of cyphopod swollen and papillate, not as broad as basal portion, separated from basal portion by wide groove across caudal face, a portion of distal lobe projecting into groove near its midpoint.
Distribution. — Known from several counties in central California.
Type.^Imm. male (RVC). Locality: California, Brookdale. Type of discipulus: male (RVC). Locality: California, lone. Type of friantus: male (RVC). Locality : California, Fresno County, Friant.
Specimens Examined. — 33 (21 males, 12 females).
California. — "California" (1 male) (MCZ) ; (3 males, 5 females) (ANSP) ; (1 male, 1 female) E. D. Cope (ANSP). Alameda County: Berkeley, Strawberry Canyon, April 9, 1938 (1 male), T. P. Maslin (CAS); Niles Canyon, March 11, 1928 (2 males, 1 female), E. C. Vandyke (CAS). Amador County: lone, March 27, 1941 (1 male, holotype of discipulus) , J. C. Chamberlin (RVC). Contra Costa County: Antioch, March 5, 1954 (1 female), H. B. Leech (CAS) ; Mt. Diablo, Corall Hollow, March 6, 1931 (4 males, 1 female), M. Olney (CAS). Fresno County: Friant, March, 1913 (1 male, paratype of friantus), R. V. Chamberlin (RVC). San Joaquin County: Clements, March 27, 1941 (1 male, labelled paratype of ergus), S. and D. Mulaik (RVC). Santa Clara County: Stanford (4 males, 1 female) (MCZ); Orinda, April 3, 1938 (1 female), Maslin (CAS) ; San Jose, Feb. 6, 1930 (1 female), L. E. Slevin (CAS). Santa Cruz County: Brookdale, March 13, 1913 (1 male, type of castaneus), R. V. Chamberlin (RVC). Tulare County: Sequoia Park, April 10, 1949 (1 male), O. Bryant (CAS).

Tylobolus castaneus is a species of millipede in the family Spirobolidae. It is found in Northern California, typically between Fresno and Contra Costa.