Studies on Spiroboloid Millipeds. XIII. A third species of the genus Trachelomegalus from Borneo (Pachybolidae)

Pachybolid millipeds are presently known to occur in a rather narrow paraequatorial belt from West Africa eastward across the continent, with a sparse contingent in South Africa and Madagascar, to south India and southeast Asia and the Greater Sunda Islands. At the easternmost end of this range the group is represented by the anatomically rather disjunct taxon Trachelomegalus on the island of Borneo. For a long time this generic name was used (chiefly by Attems) for species occurring in Sumatra and Indochina as well as Borneo; it was not until 1963 that I could publish a distinction resulting in the revival of Tonkinbolus (Verhoeff, 1938) for the mainland forms. Since that time Trachelomegalus has remained essentially monotypic (T. modestior Chamberlin, 1921, being inadequately documented), and judged from the paucity of museum material, the type species itself has been only rarely collected. So long as only one member of a genus is known, one can never confidently distinguish specific from generic characters, and it was thus a matter of satisfaction for me to recently discover material of a distinctive third member of this genus from Borneo. This species is known from two adult males in the Rijksmuseum van Natuurlijke Historie at Leiden, kindly loaned to me for study by Dr. L. van der Hammen, to whom I here express my appreciation. Trachelomegalus (Gk. trachelos, neck; megalos, enlarged) Trachelomegalus Silvestri, 1896, Ann. Mus. civ. Stor. nat. Genova, 36: 27. Monobasic. Type species, Spirobolus hoplurus Pocock, 1893, by original designation and monotypy. — Hoffman, 1963, Rev. Suisse Zool., 69: 768. Diagnosis: Medium sized pachybolids with the collum enlarged and ex-