This genus was first described in 1896 by the American biologistOrator F. Cook, who placed this genus in the family Ballophilidae, which he introduced to contain this new genus. In subsequent decades, however, some authorities rejected the taxonomic rank proposed by Cook, instead placing Ballophilus in a subfamily (Ballophilinae) within the family Schendylidae. Others placed this genus in Ballophilidae, which they accepted as a separate family, a rank that eventually gained broad support from authorities.
In 2014, however, a phylogenetic analysis of the orderGeophilomorpha using both morphological and molecular data found representatives of the family Ballophilidae, including species of Ballophilus, nested among species of the family Schendylidae. To avoid paraphyly of the family Schendylidae with respect to Ballophilidae, authorities dismissed Ballophilidae as a separate family. Authorities now place the genera formerly contained in the family Ballophilidae, including Ballophilus, in the family Schendylidae instead, sometimes in the subfamily Ballophilinae. Nevertheless, some references still place Ballophilus in Ballophilidae, which they accept as a valid family.
Description
Centipedes in this genus feature antennae that are conspicuously shaped like clubs. The middle part of the labrum is a thin membrane without teeth, but the side pieces feature teeth. The forcipularsternum lacks distinct chitin lines but may feature a faint thickening of the cuticle starting at the forcipular condyle. The sternites feature circumscribed fields of pores, and these fields are either nearly circular or transversally elliptical. The basal element of each of the ultimate legs (coxopleuron) usually features two pores. These pores connect to coxal organs with a simple structure (with each pore connecting to a single gland through a single duct that does not branch) rather than a composite structure (with multiple ducts from distinct glands converging to connect to each pore). At the distal end of each of the ultimate legs is a tubercle with a seta instead of a claw.
Species in this genus range from about 1cm to about 7cm in length and feature 37 to 91 pairs of legs. The Asian species Ballophilus pallidus measures only 11mm in length and can have as few as 37 leg pairs (37 or 39 in males, 41 in females), the minimum number found in this genus. Both B. fijiensis and B. giganteus can have as many as 91 leg pairs, the maximum number found in this genus, but B. giganteus is also notable for its large size, reaching 75mm in length.
Phylogeny
This genus is probably closely related to the genera Ityphilus and Diplethmus. In 2014, a phylogenetic analysis of the order Geophilomorpha using both molecular data and morphology found a representative of the genus Ballophilus nested among species of Ityphilus in a phylogenetic tree of this order. This evidence suggests that some species of Ityphilus may be more closely related to some species of Ballophilus than to other species of Ityphilus and that Ityphilus may be paraphyletic with respect to Ballophilus.
The genera Ballophilus and Ityphilus share a distinctive set of traits. For example, the antennae in both genera are thicker toward the distal end, producing a distinctly club-like shape. Furthermore, as in some species of Ityphilus, the antennae in Ballophilus are bent in the middle. Moreover, in both genera, the middle of the labrum is a thin membrane without teeth, the sternites of leg-bearing segments feature rounded and well defined pore fields, and each of the ultimate legs features seven articles with two pores on the coxopleuron.
Species of Ballophilus can be distinguished from their close relatives in Ityphilus, however, based on other traits. For example, the forcipular sternite features chitin lines in Ityphilus, but these lines are entirely or virtually absent in Ballophilus. Furthermore, the posterior part of the clypeus in Ballophilus features smooth areas (plagulae) that are absent in Ityphilus, and the coxosternite of the second maxillae is divided down the middle by a longitudinal groove in Ballophilus but not in Ityphilus.
↑Chamberlain, Ralph V. (1920). "The Myriopoda of the Australian Region". Bulletin of the Museum of Comparative Zoology at Harvard College. 64: 1–269 [37] – via Biodiversity Heritage Library.
↑Demange, J.-M. (1963). "Chilopoda: La Réserve Naturelle Integrale du Mont Nimba". Mémoires de l'Institut Français d'Afrique Noire (in French). 66 (5): 41–118 [68].
