Bioacoustics of Heteroctenus

DIAGNOSIS: Heteroctonus differs all from other rhopalurusine genera by the presence of a single, deep, median depression in the male pectinal plate. It differs further from Ischnotelson , gen. nov. , Jaguajir , gen. nov. , Physoctonus , Rhopalurus , Troglorhopalurus , and many species of Centruroides by the absence of a subaculear tubercle on the telson; from Centruroides , Ischnotelson , Physoctonus , and Troglorhopalurus by the presence of a pecten-sternite stridulatory organ (proximal pectinal teeth often enlarged, dorsal surfaces with multiple nodules and regular striations, sternite III, lateral margins forming smooth, raised carina, ventromedian carina elevated anteriorly, ventrosubmedian surfaces forming paired depressions, finely and irregularly granular); from Ischnotelson and Rhopalurus , by the separate (unfused) central lateral and posterior central submedian carinae of the carapace; from Centruroides by the presence of macrosetae on the dorsobasal surface of the pectinal teeth; from Ischnotelson , by the separate (unfused) lateral ocular and central lateral carinae of the carapace, and the telson vesicle not being laterally compressed; from Jaguajir by the separate (unfused) lateral ocular and anterior central submedian carinae of the carapace; from Physoctonus by the larger size (30–70 mm), the more distinct carapacial carinae, the setose proximal dorsal fulcra of the pectines, the incrassate pedipalp chela manus of the adult male, the bifurcate prolateral pedal spur of leg I, and the oblique subrows of primary denticles on the pedipalp chela fingers flanked closely by pro- and retrolateral accessory (supernumerary) denticles; and from Troglorhopalurus by the proximal dentate margin of the chela fixed and movable fingers of the adult male emarginate, with a distinct gap evident between them, when closed.