A review of the millipede genus Sinocallipus Zhang, 1993 (Diplopoda: Callipodida: Sinocallipodidae), with notes on gonopods monotony vs. peripheral diversity in millipedes

The millipede genus Sinocallipus is reviewed, with four new cave-dwelling species, Sinocallipus catba, Sinocallipus deharvengi, Sinocallipus jaegeri and Sinocallipus steineri, being described from caves in Laos and Vietnam. With the new records the number of species in the genus reaches six and the genus range is extended to Central Vietnam and North and Central Laos. Both, Sinocallipus jaegeri from Khammouan Province in Laos and Sinocallipus simplipodicus Zhang, 1993 from Yunnan, China, show high level of reduction of eyes, which has not been recorded in other Callipodida. Peripheral characters such as the relative lengths of antennomeres, the number of ocelli, the number of pleurotergites or even the shape of paraprocts and the coloration seem to provide more information for the distinction of the species than do the relatively uniform gonopods. The differences in gonopods mainly concern the shape and length of cannula, the length and shape of coxal processes g and k, and the number of the acicular projections of the femoroid. An explanation is offered for the function of the trochanteral lobe of 9th leg-pair. It provides mechanical support for the cannula and seems to assist sperm charge and insemination during copulation. An identification key to the species in the genus is produced to accommodate the new species. The new species descriptions were automatically exported at the time of publication to a wiki (www.species-id.net) through a specially designed software tool, the Pensoft Wiki Convertor (PWC), implemented here for the first time together with a newly proposed citation mechanism for simultaneous journal/wiki publications.