Bioacoustics of Tibicinoides boweni

Diagnosis. Okanagana boweni is a large-bodied species most similar to allopatric O. simulata in body size and habitus but to sympatric O. utahensis in color pattern ( Fig. 1 ). Diagnosis of museum specimens may be accomplished by a suite of characters, some of which are visible on spread specimens with pulled genitalia and others on unprepared specimens. In unprepared specimens a character combination is necessary for diagnosis of the three similar species. A quadrate pronotum with parallel lateral margins separates O. boweni and O. simulata from O. utahensis , which has an anteriorly constricted pronotum, and a broad longitudinal yellow sulcus on the anterior half of the pronotum separates O. boweni and O. utahensis from O. simulata , in which the sulcus is barely indicated and faintly marked ( Fig. 1 ). Thus, O. boweni possesses both a quadrate pronotum with a broad yellow longitudinal sulcus. Less reliable diagnostic characters include the semicircle of mesonotal markings, which tend to be more extensive in O. boweni and O. utahensis compared with those of O. simulata , the head width narrower than the anterior margin of the pronotum in O. boweni but subequal in O. simulata , and the posterior pronotal margin appearing complete in O. boweni but incomplete in O. simulata due to a darkened median constriction in the latter ( Fig. 1 ). On prepared specimens the uncus and aedeagus are valuable characters for diagnosing the two species ( Fig. 3 ). Uncus shape should be used in conjunction with other characters due to intraspecific variation that is found generally throughout Okanagana (WCT pers. obs.). In dorsal view, the uncus of O. boweni has parallel lateral margins that converge towards the apex with a distinct angle that begins at one half to two thirds of its length, compared with the gradually and smoothly curved lateral margins of O. simulata and O. utahensis . When exposed in lateral view, the aedeagus is a singular character that diagnoses O. boweni from both O. simulata and O. utahensis . The posterior edge of the aedeagus is long and incurved in O. boweni , forms an acute angle in O. simulata , and is uniformly straight and short in O. utahensis with its posterior margin situated perpendicular to the plane of the uncus ( Fig. 3 ). Female O. boweni may be diagnosed by the lack of the deep secondary notch on the 7th abdominal sternite found in O. simulata and to a lesser extent in O. utahensis females ( Fig. 4 ). For O. utahensis without clearly indicated secondary notches, diagnosis may require examination of pronotal shape or the condition of the longitudinal sulcus ( Fig. 1 ). O. boweni is sympatric with O. utahensis but can be diagnosed from the latter in the field by the larger body size ( Table 1 ) and quadrate aspect of the pronotum of O. boweni , in contrast with the smaller body size and trapezoidal aspect lent by the anterior convergence of the lateral pronotal margins in O. utahensis ( Fig. 1 ). The morphology of the male ( Fig. 3 ) and female ( Fig. 4 ) terminalia are also diagnostic. Species Body length Expanse of forewings Width of head across eyes O. boweni sp. n. (n=19)* 26.9 ± 1.5: 29.0 69.8 ± 2.5 (n=6): 65.3 8.8 ± 0.3: 8.5 O. simulata (n=11) O. utahensis (n=12) 26.0 ± 0.9: 27 23.3 ± 1.2: 24.5 73.6 ± 2.1 (n=8): 75 61.7 ± 2.1 (n=3): 60 8.7 ± 0.3: 9 7.7 ± 0.4: 8 Bioacoustics. The male calling song of O. boweni is a continuous train of syllables with a single dominant frequency that is similar to the calls of both O. simulata and O. utahensis ( Table 2 ; Fig. 5 ; see Chatfield-Taylor & Cole 2019 ). Amplitude modulation at a rate of 7.82 ± 0.47 s- 1 (n = 4) may elaborate the song structure ( Fig. 5 ), and when this occurs a wavering quality is imparted to the song as it oscillates in loudness. Amplitude modulations often began or became more pronounced when males were disturbed or approached, behavior that was also observed in O. simulata and O. utahensis (JAC, pers. obs.). Species Syllable rate (s-1) Peak frequency (kHz) O. boweni sp. n. (n = 8) 179.5 ± 5.9: 180.2 7.89 ± 0.54: 8.36 Lone Pine (n = 3) 174.7 ± 3.2 7.67 ± 0.6 Tamarack Beach type locality (n = 5) 182.4 ± 5.4 8.0 ± 0.5 O. simulata (n = 7) 188.1 ± 3.4 7.92 ± 0.3 O. utahensis (n = 6) 362.1 ± 63.7 8.46 ± 0.38 Neither syllable rate (ANCOVA, P = 0.111) nor peak frequency ( P = 0.653) varied with temperature. Songs differed significantly between species (MANOVA, P = 4.74x10 -4 ) but not between O. boweni populations ( P = 0.543). Of the three species, O. utahensis was most divergent in song, but songs of O. boweni and O. simulata also differed significantly ( P = 5.2x10 -3 ), differences that were again not explained by population ( P = 9.08x10 -2 ). Per the methodology of Chatfield-Taylor and Cole (2019) , the calls of O. boweni and O. simulata were separated by 0.09 standard deviations (SD) in parameter space while separation between O. boweni and O. utahensis ranged from 0.85 to 2 SD.